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3,300
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Equivalence of the standard monophasic waveform shocks delivered by automated external defibrillators?
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To study whether two different types of monophasic waveform shocks (i.e. monophasic damped sinusoidal [MDS] and monophasic truncated exponential [MTE] waveform shocks) are of equivalent efficacy.</AbstractText>Retrospective review of defibrillation efficacy and outcome in ventricular fibrillation/ventricular tachycardia (VF/VT) patients treated in the same EMS system with AEDs delivering either MDS waveform shocks (n=40) or MTE waveform shocks (n=40).</AbstractText>Defibrillation efficacy of the first shock was 82.5% in the MDS group and 70% in the MTE group (P=0.19). Termination of VF by at least one of the first three shocks was found in 95 and 85% of the patients treated with MDS and MTE waveform shocks, respectively (P=0.22). Restoration of spontaneous circulation occurred in 75% of the MDS group and 30% of the MTE group (P=0.0001). Hospital admission rates were 52.5% in the MDS group and 17.5% in the MTE group (P=0.001). Hospital discharge rates were 17.5% in the MDS group and 7.5% in the MTE group (P=0.18).</AbstractText>Our data suggest disparity in efficacy between MDS waveform shocks and MTE waveform shocks. Furthermore, our findings should be taken into consideration when the issue of the control group(s) in future clinical trials on new waveforms is discussed.</AbstractText>
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3,301
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Characteristics and outcome among patients suffering from in hospital cardiac arrest in relation to the interval between collapse and start of CPR.
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To describe survival after in-hospital cardiac arrest in relation to the interval between collapse and start of cardiopulmonary resuscitation (CPR).</AbstractText>All patients suffering in-hospital cardiac arrest in Sahlgrenska University Hospital in Göteborg, Sweden between 1994 and 1999 in whom resuscitative efforts were attempted and for whom the interval between collapse and start of CPR was known.</AbstractText>Prospective recording of various factors at resuscitation including the interval between collapse and start of CPR. Retrospective evaluation via medical records of patients' previous history, clinical situation prior to cardiac arrest and final outcome.</AbstractText>Survival to discharge was 33% among the 344 patients in whom CPR was started within the first minute as compared with 14% among the 88 patients in whom CPR started more than 1 min after collapse (P=0.008). The corresponding figures for patients found in ventricular fibrillation was 50 versus 32% (NS); for patients found in pulseless electrical activity 9 versus 3% (NS) and for patients found in asystole 19 versus 0% (NS). Correcting for dissimililarties in the previous history and factors at resuscitation, the adjusted odds ratio and 95% confidence limits for being discharged from hospital when CPR was started within 1 min compared with a later start was 3.06 with 95% confidence limits of 1.59-6.31.</AbstractText>Among patients with in-hospital cardiac arrest in whom the interval between collapse and start of CPR was known, we found that in 80% of the cases CPR was started within the first minute after collapse. Among these patients, survival to discharge was twice that of patients in whom CPR was started later. These results highlight the importance of immediate CPR after in-hospital cardiac arrest.</AbstractText>
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3,302
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Influence of early defibrillation on the survival rate and quality of life after CPR in prehospital emergency medical service in a German metropolitan area.
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Early defibrillation by emergency medical personnel has been shown to improve survival in patients suffering from out-of-hospital cardiac arrest with ventricular fibrillation. Due to organisational differences it is difficult to compare results in various studies. Comparison of studies has been simplified by introduction of the Utstein template. After introduction of an early defibrillation program in Hamburg, we compared the patients being treated with early defibrillation by emergency medical technicians (EMTs) with patients being defibrillated by physicians in an out-of-hospital emergency service in a prospective study. All patients suffered from non EMT-witnessed ventricular fibrillation of cardiac origin. During 1 year, 103 patients were analyzed with respect to survival rate and quality of life. Of the 53 patients in the early defibrillation group (G1) 11 regained a palpable pulse at physicians' arrival, whereas all patients of the control group (G2) showed ventricular fibrillation. More patients treated with early defibrillation regained sinus rhythm without antiarrhythmics in the prehospital phase (G1: n=43 (86%); G2: n=32 (60%); P<0.05) and had a shorter in-hospital stay (G1: median, 23 days; range 5-51 days; G2: median 39, range 15-88 days; P<0.05). Twelve patients in G1 and 16 in G2 were discharged from hospital. The survival rate was similar in both groups (after 6 months G1: n=12; G2: n=14, after 12 months G1: n=10; G2: n=13 and after 24 months G1: n=9; G2: n=10), and the quality of life according to Glasgow-Pittsburgh Cerebral Performance Category (CPC) and Overall Performance Category (OPC) scores also was comparable between groups. We conclude that early defibrillation provides a higher incidence of return of a spontaneous circulation, a reduced need for antiarrhythmics and shorter in-hospital treatment times in patients with out-of-hospital ventricular fibrillation.
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3,303
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Perioperative management of long QT syndrome in a child with congenital heart disease.
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During cardiac catheterization, a 2(1/2)-year-old boy developed sudden cardiac arrest. The presence of a long QT interval in the electrocardiogram (ECG) along with ventricular arrhythmia and syncope at that moment enabled us to diagnose long QT syndrome (LQTS). Immediate defibrillation and beta-blocker (metoprolol) therapy saved the life of the child. Cardiac catheterization was completed and the child was planned for Fontan operation. Beta-blocker coverage, prevention of sympathetic stimulation and avoidance of agents which prolong the QT interval made anesthesia uneventful. There were episodes of ventricular fibrillation (VF) in the postoperative period. The child was managed with electrical defibrillation, metoprolol and magnesium.
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3,304
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Electrical restitution and cardiac fibrillation.
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Combined experimental and theoretical work has shown that restitution properties of the cardiac action potential duration and conduction velocity contribute to breakup of reentrant wavefronts during cardiac fibrillation independent of preexisting electrophysiologic heterogeneities in the tissue. Developing therapies that favorably alter these cardiac electrical restitution properties are a promising new approach to preventing fibrillation.
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3,305
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Risk of sudden death after successful accessory atrioventricular pathway ablation in resuscitated patients with Wolff-Parkinson-White syndrome.
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Cardiac arrest in patients with Wolff-Parkinson-White (WPW) syndrome can be due to ventricular fibrillation mediated by fast conduction over the accessory pathway during atrial fibrillation. However, if primary ventricular fibrillation is the reason for resuscitation, placement of an implantable cardioverter defibrillator (ICD) would be indicated. The aim of this study was to test the hypothesis that in resuscitated patients with WPW syndrome, recurrences can be prevented by sole ablation of their accessory pathways.</AbstractText>We performed a long-term follow-up study of 48 resuscitated patients with WPW syndrome who underwent successful accessory pathway ablation as their sole primary treatment. Cardiac arrest had occurred either spontaneously in 32 patients (group A) or after intravenous administration of antiarrhythmic drugs in 16 patients (group B) and was never associated with an acute myocardial infarction or other concomitant factors. All patients had normal left ventricular function at echocardiography. A total of 56 accessory AV pathways were ablated successfully with radiofrequency current (n = 55) or during surgery (n = 1) and were located at the left free wall (n = 35), right free wall (n = 8), or septal-paraseptal region (n = 13). Follow-up 5.0+/-1.9 years after ablation (range 0.2 to 7.9) was obtained in all 48 patients. All of the patients were alive, and none had a life-threatening arrhythmia or syncope after successful ablation of their accessory pathways.</AbstractText>In resuscitated patients with WPW syndrome who have normal left ventricular function at echocardiography and no ECG abnormalities suggesting additional electrical disease, ablation of their overt accessory pathways prevented cardiac arrest recurrences; therefore, ICD placement is generally not indicated.</AbstractText>
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3,306
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Myocardial protection during ventricular fibrillation by inhibition of the sodium-hydrogen exchanger isoform-1.
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Activation of the sarcolemmal sodium-hydrogen exchanger isoform-1 (NHE-1) in response to the intense intracellular acidosis that develops during ischemia has been identified as an important mechanism of myocardial cell injury. NHE-1 inhibition in the quiescent (nonfibrillating) heart ameliorates functional manifestation of ischemia and reperfusion injury. We investigated in isolated heart and intact rat models of ventricular fibrillation whether NHE-1 inhibition, by using the selective inhibitor cariporide, could ameliorate myocardial abnormalities that develop during ventricular fibrillation and limit resuscitability and survival. In the isolated rat heart, cariporide significantly reduced the magnitude of ischemic contracture during ventricular fibrillation and the accompanying increases in coronary vascular resistance. Hearts that had received cariporide during ventricular fibrillation had no diastolic dysfunction after resuscitation and recovered their systolic function earlier. In intact rats, cariporide given immediately before starting chest compression allowed generation of a coronary perfusion pressure and end-tidal Pco2 comparable with control rats but with significantly less depth of compression. Cariporide had an unprecedented effect in this rat model, prompting spontaneous defibrillation after approximately 8 mins of chest compression. After resuscitation, rats treated with cariporide had significantly less ventricular ectopic activity, better hemodynamic function, and higher survival rates (22 of 24 [94%] vs. 15 of 24 [63%] in control rats, p <.05). We conclude that NHE-1 inhibition may represent a novel and highly effective form of treatment for resuscitation from ventricular fibrillation.
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3,307
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Sex-related differences in the presentation and outcome of out-of-hospital cardiopulmonary arrest: a multiyear, prospective, population-based study.
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To examine whether previously observed sex-related differences in coronary artery disease syndromes also apply to patients with out-of-hospital sudden cardiac arrest, a probable subset of patients with coronary artery disease who are easy to recognize and are treated in a standardized fashion.</AbstractText>Prospective, population-based study conducted over a 6-yr period.</AbstractText>A large urban municipality (population, 1.1 million) served by a single emergency medical services system with centralized medical direction and standardized protocols.</AbstractText>All patients with out-of-hospital, nontraumatic, primary cardiac arrest.</AbstractText>Standardized advanced cardiac life support protocols.</AbstractText>During the 6 yrs of the study, 4147 consecutive patients were studied, 42% of whom were women (p <.001). Although women were significantly older than men (mean age, 68.7 +/- 18 vs. 61.7 +/- 17 yrs; p =.001), there were no significant differences for the percentages of witnessed and unwitnessed arrests, response intervals, and the length and type of treatment provided. Although men were more likely to have ventricular fibrillation/ventricular tachycardia on presentation (41% vs. 30%), women had more asystole (8.8% vs. 7%) and (organized) pulseless electrical activity than men (24% vs. 18%; p <.001). Nevertheless, more women were resuscitated (13.5% vs. 10.7%; p =.005), particularly women with non-ventricular fibrillation/ventricular tachycardia presentation (12.6% vs. 9.6%; p <.02). These differences were more pronounced when controlling for age (95% confidence interval, 1.44 [1.25-1.74]).</AbstractText>In cases of out-of-hospital sudden cardiac arrest, women have significantly better resuscitation rates than men, especially when controlling for age, particularly among women with non-ventricular fibrillation/ventricular tachycardia presentations. Additional studies are required to validate these observations, not only for long-term survival and external validity, but also for other potential genetic factors and potential discrepancies with other studies.</AbstractText>
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3,308
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Off-pump coronary artery bypass grafting in patients with left ventricular dysfunction.
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Coronary artery bypass grafting in patients with severe left ventricular (LV) dysfunction still remains a high risk procedure due to its high mortality and morbidity. Off-pump surgery can be an alternative technique in these patients. We analyzed our results of off-pump coronary surgery in patients with left ventricular dysfunction and compared them with patients operated on-pump.</AbstractText>Between January 1997 and December 2000, 355 patients with LV dysfunction (EF equal to or less than 30%) underwent off-pump coronary artery bypass (OPCAB) surgery. During the same period, 959 patients with LV dysfunction underwent coronary artery surgery on cardiopulmonary bypass. Octopus was used as mechanical stabilizer and intracoronary shunts were used in most patients. The mean age of the patients was 57.7 +/- 9.2 in patients operated on-pump and 58.4 +/- 9.8 in patients operated off-pump.</AbstractText>The preoperative variables were comparable in two groups, except that there were more patients with triple vessel disease in on-pump group. Average number of grafts was 2.8 +/- 0.7 and 3.3 +/- 0.7 (p<0.001) in off-pump and on-pump groups respectively. The mortality was 3.9% and 6.0% (p = 0.176) in off-pump and on-pump groups respectively. Postoperative morbidity was less in off-pump group but it was statistically significant in incidence of atrial fibrillation and prolonged ventilation which were low in off-pump group. The hospital stay was significantly less in patients operated off-pump.</AbstractText>OPCAB surgery can be safely performed in patients with LV dysfunction. The postoperative morbidity and length of stay is less as compared to patients operated on-pump.</AbstractText>
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3,309
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[Effects of preceding stable or unstable angina on hospital morbidity-mortality of myocardial infarction. Results of a continuous series of 1,910 patients].
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The aim of this study was to determine the effect of preceding unstable angina on the short-term prognosis of myocardial infarction based on early complications: cardiac failure, cardiac rupture, ventricular septal defect, sustained ventricular tachycardia ventricular fibrillation and hospital mortality. A continuous series of 1,910 patients admitted with 7 days of myocardial infarction was analysed retrospectively. The patients were divided into two groups according to their previous coronary history: Group A (myocardial infarction preceded by unstable angina) and Group B (myocardial infarction without preceding unstable angina). Group B was subdivided into Group B1 (myocardial infarction de novo) and Group B2 (myocardial infarction with previous stable angina). The results showed that patients with previous unstable angina (Group A) had a lower hospital mortality (7.9%) than those without (Group B) (13.3%) (p = 00017), fewer cardiac ruptures (1.1 versus 2.9%, p = 0.03) and less ventricular fibrillation (2.6 versus 4.5%, p = 0.053). Subgroups analysis showed that patients with de novo myocardial infarction (Group B1) had more sustained ventricular tachycardia than those with previous stable angina (Group B2) (5.3 versus 2.7%, p = 0.04). The authors conclude that pre-infarction unstable angina, possibly by ischaemic pre-conditioning, is an independent factor of a better prognosis in myocardial infarction.
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3,310
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Risk stratification for postoperative cardiovascular events via noninvasive assessment of endothelial function: a prospective study.
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Brachial artery endothelial function is impaired in individuals with atherosclerosis and coronary risk factors and improves with risk reduction therapy. However, the predictive value of brachial artery endothelial dysfunction for future cardiovascular events is unknown.</AbstractText>We preoperatively examined brachial artery vasodilation using ultrasound in 187 patients undergoing vascular surgery. Patients were prospectively followed for 30 days after surgery. Forty-five patients had a postoperative event, including cardiac death (3), myocardial infarction (12), unstable angina/ischemic ventricular fibrillation (2), stroke (3), or elevated troponin I, reflecting myocardial necrosis (25). Preoperative endothelium-dependent flow-mediated dilation was significantly lower in patients with an event (4.9+/-3.1%) than in those without an event (7.3+/-5%; P<0.001), whereas endothelium-independent vasodilation to nitroglycerin was similar in both groups. In a Cox proportional-hazards model, the independent predictors of events were age (P=0.001), renal insufficiency (P=0.03), noncarotid surgery (P=0.05), and lower brachial artery flow-mediated dilation (P=0.007). If troponin I elevation was not considered an event, low flow-mediated dilation remained an independent predictor of risk (odds ratio 9.0, 95% CI 1.2 to 68; P=0.03). When a flow-mediated dilation cutpoint of 8.1% was used, endothelial function had a sensitivity of 95%, specificity of 37%, and negative predictive value of 98% for events.</AbstractText>Impaired brachial artery endothelial function independently predicts postoperative cardiac events, which supports a role for endothelial dysfunction in the pathogenesis of cardiovascular disease. The strong negative predictive value of preserved endothelial function raises the possibility that assessment of brachial artery flow-mediated dilation will be useful in the management of patients undergoing vascular surgery.</AbstractText>
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3,311
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[A case of postoperative acute myocardial infarction due to the interruption of anticoagulant therapy].
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A 67-year-old male patient was scheduled for stripping of a lower limb varix. He had received long-term anticoagulant therapy using oral warfarin because of implantation of an aortic mechanical heart valve. Warfarin therapy was discontinued 3 days before surgery to prevent excessive bleeding during the perioperative period. Anesthesia was maintained with sevoflurane and nitrous oxide in oxygen and combined with continuous epidural block. The operation was uneventful. Six hours after surgery, an electrocardiogram demonstrated ventricular fibrillation, followed by respiratory arrest. Cardiopulmonary resuscitation was started immediately, and normal sinus rhythm was restored. Coronary angiography revealed significant stenosis of coronary arteries. Percutaneous transluminal coronary angioplasty was therefore performed. Acute myocardial infarction caused by the interruption of anticoagulant therapy was suspected.
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3,312
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Glyburide prevents isoflurane's reducing effects on hydroxyl radical formation in the postischemic reperfused rat heart.
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The role of K(ATP) channels in isoflurane's reducing effects on oxygen free radical formation are not well known.</AbstractText>To investigate whether glyburide, an ATP-regulated potassium (K(ATP)) channel blocker, abolishes isoflurane-induced cardioprotective effects and whether it affects hydroxyl radical formation in the postischemic reperfused heart.</AbstractText>Thirty-nine male Wistar rats were divided into four groups: group C (control, n=10), group I (isoflurane, n=9), group G (glyburide, n=10) and group GI (glyburide and isoflurane, n=10). The hearts were perfused as a Neely's working heart model. Afterwards, global heart ischemia was induced for 15 min followed by reperfusion for 20 min. The formation of hydroxyl radicals in the coronary effluent and heart was measured with high performance liquid chromatography.</AbstractText>Isoflurane alone and glyburide alone produced significant decreases in the duration of ventricular fibrillation during reperfusion (group C 452+/-345, group I 247+/-60, group G 261+/-135 s; P<0.05). In the presence of glyburide, isoflurane did not further decrease the duration of arrhythmia (group GI 230+/-48 s). Isoflurane reduced hydroxyl radical formation significantly in the coronary effluent during ischemia and reperfusion, but this was prevented by glyburide.</AbstractText>The results suggest that isoflurane reduces hydroxyl radical formation, at least in part, through activation of K(ATP) channels.</AbstractText>
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3,313
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Effects of adrenaline pretreatment on the arrhythmias observed following ischemia and reperfusion in conscious and anesthetized rats.
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A short episode of ischemia induced by coronary artery occlusion can precondition the myocardium against arrhythmia. The factors that have the potential to protect the myocardium from subsequent ischemia and reperfusion are controversial. In this study, the preconditioning-like effects of adrenaline were investigated in both anesthetized and conscious rats. Adrenaline 0.1 and 0.5 mg/kg or saline was administered 10 min before coronary occlusion in conscious and anesthetized rats. The 0.5 mg/kg dose of adrenaline decreased the total duration of arrhythmia in both models. The incidence of ventricular fibrillation decreased and survival rate increased only in conscious rats administered 0.5 mg/kg adrenaline. As a result, it is suggested that exogenous administration of adrenaline before coronary ligation may precondition and protect the heart against arrhythmia.
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3,314
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An emergency department observation unit protocol for acute-onset atrial fibrillation is feasible.
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We sought to describe the feasibility of an emergency department observation unit (EDOU) treatment protocol for the management of uncomplicated acute-onset atrial fibrillation (AAF).</AbstractText>This descriptive case series took place at a major suburban, university-affiliated teaching hospital. Patients were prospectively enrolled in an EDOU treatment protocol if they had uncomplicated AAF that failed initial ED attempts to convert to sinus rhythm. In the EDOU, patients underwent ECG monitoring, serial creatine kianse MB measurements, and further rate control with optional electrical cardioversion. Primary outcomes measured were EDOU rate of conversion to sinus rhythm, rate of discharge home, length of stay, positive diagnostic outcomes, complications of AAF, and 7-day return visits.</AbstractText>Sixty-seven patients were studied. Patients were symptomatic for a median of 4.0 hours, had mean initial ED pulse rates of 137+/-23 beats/min, and spent 4.7+/-2.2 hours in the ED before transfer to the EDOU. While in the EDOU, 55 (82%) patients converted to sinus rhythm. Five (7%) patients were admitted because of positive test results: 2 for myocardial infarction, 2 for fever, and 1 for ventricular tachycardia. Twelve (18%) patients remained in atrial fibrillation, with 9 admitted and 3 discharged. Overall, 81% of patients were discharged in 11.8+/-7.0 hours, and 19% were admitted after 17.6+/-9.5 hours of observation. Three discharged patients returned within 7 days, 2 for uncomplicated recurrent AAF and 1 for chest pain subsequently found to be noncardiac in origin. There were no major complications attributable to the EDOU protocol.</AbstractText>Selected patients with AAF for whom initial ED management fails can subsequently be managed in an EDOU with a high short-term conversion and discharge rate.</AbstractText>
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3,315
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Effects of active compression-decompression cardiopulmonary resuscitation with the inspiratory threshold valve in a young porcine model of cardiac arrest.
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Active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) with the inspiratory threshold valve (ITV) has been recently recommended by the American Heart Association for treatment of adults in cardiac arrest (class IIb: alternative, useful intervention), but this new technique has never been used in a pediatric population. Thus, this study was designed to evaluate ACD + ITV CPR in a young porcine model of cardiac arrest. After 10 min of ventricular fibrillation, and 8 min of standard CPR, ACD + ITV CPR was performed in seven 4- to 6-wk-old pigs (8-12 kg); defibrillation was attempted 8 min later. Within 2 min after initiation of ACD + ITV CPR, mean (+/- SEM) coronary perfusion pressure increased from 18 +/- 2 to 24 +/- 3 mm Hg (p = 0.018). During standard versus ACD + ITV CPR, mean left ventricular myocardial and total cerebral blood flow was 59 +/- 21 versus 126 +/- 32 mL.min(-1).100 g(-1), and 36 +/- 7 versus 60 +/- 15 mL.min(-1).100 g(-1), respectively (p = 0.028). Six of seven animals were successfully defibrillated, and survived >15 min. In conclusion, the combination of ACD + ITV CPR significantly increased both coronary perfusion pressure and vital organ blood flow after prolonged standard CPR in this young porcine model of ventricular fibrillation.
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3,316
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Headache as a manifestation of fatal myocardial infarction.
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Cardiac ischemia typically causes chest pain, variously radiating elsewhere. Convergence of cardiac nerve fibers on central pathways receiving somatic afferents from the head is likely to be responsible for the perception of cardiac ischemic pain as headache. A 47-year-old man was admitted to the emergency room of our hospital with a 2-hour history of occipital headache. Routine electrocardiography revealed monophasic ST-segment elevation in leads I and aVL and ST-segment depression in leads II, III, and aVF. During recording of lead VI, ventricular fibrillation occurred. Advanced life support was started immediately but failed to restore rhythm and cardiac function. Autopsy showed two-vessel disease with a ruptured plaque and total thrombotic occlusion of the proximal left anterior descending artery and 80% stenosis of the right coronary artery. In this patient, headache was the only symptom of myocardial ischemia. Anatomic convergence of cardiac nerve fibers on central pathways receiving somatic afferents from the head is likely to be responsible for the perception of cardiac ischemic pain as headache. Owing to the very rare occurrence of headache as a symptom of myocardial ischemia, diagnosis is difficult and requires a high degree of suspicion.
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3,317
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Cytokine responses to myocardial revascularization on cardiopulmonary bypass: intermittent crossclamping versus blood cardioplegic arrest.
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The inflammatory responses to the different myocardial protection approaches have not been thoroughly investigated. We sought to study the cytokine responses to cardiopulmonary bypass (CPB) using the intermittent aortic crossclamping with ventricular fibrillation (IAC) versus blood cardioplegic arrest (BC) techniques.</AbstractText>Perioperative plasma levels of tumor necrosis factor a (TNF-alpha), interleukins (IL) 6, 8, 10, and cardiac troponin-I (cTnI) were measured serially before surgery, at the end of surgery, and 2, 24, and 48 hours after elective coronary revascularization in 31 patients (IAC: n=15; BC: n=16).</AbstractText>Demographics, preoperative status, and number of grafts (IAC: 2.7 +/- 0.6; BC: 3.0 +/- 0.4) were similar between groups. No major complications occurred in either group. The total ischemic time and duration of CPB were shorter in group IAC (17 +/- 5 and 58 +/- 10 min vs 45 +/- 14 and 81 +/- 21 min; both p<0.01). Although the intergroup difference in postoperative cTnI levels was not statistically significant, the release of both TNF-alpha and IL-8 were higher in group IAC than in group BC. However, IL-6 and IL-10 levels were lower after surgery in group IAC.</AbstractText>Despite the duration of ischemia and CPB being shorter, intermittent aortic crossclamping is associated with an enhanced pro-inflammatory but a reduced anti-inflammatory response compared to the cardioplegic arrest technique. Its clinical relevance needs to be further defined.</AbstractText>
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3,318
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Magnesium deficiency during lactation as a precipitant of ventricular tachyarrhythmias.
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A young ICD recipient with a history of syncope and idiopathic polymorphic ventricular tachycardia/ventricular fibrillation presented after an ICD discharge. She had delivered her first child 8 days prior to the event and she had been lactating. Numerous short runs of polymorphic ventricular tachycardia/ventricular fibrillation resolved with aggressive replacement of magnesium and elimination of breast-feeding.
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3,319
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The challenge of endocardial right ventricular pacing in patients with a tricuspid annuloplasty ring and severe tricuspid regurgitation.
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On occasion, patients with a tricuspid annuloplasty ring may require permanent cardiac pacing. Although it is technically possible to pass a ventricular transvenous lead through a tricuspid valve with an annuloplasty ring, the procedure is complicated by considerable chamber enlargement and mechanical distortion of the tricuspid valve often with severe residual tricuspid regurgitation. Over a 25-month period, transvenous ventricular lead placement following insertion of a tricuspid annuloplasty ring was successfully performed in five patients (three women). The patient mean age was 66 years (range 55-77 years). Four cases had slow atrial fibrillation and another paroxysmal atrial fibrillation requiring His-bundle ablation. Two patients had mitral valve replacement and two aortic and mitral valve replacements. All patients had residual severe to torrential tricuspid regurgitation. Seven ventricular steroid-eluting screw-in leads were used. Single leads were used in three cases, whereas in two others, two ventricular leads were attached to a dual chamber pulse generator. Although technically difficult, ventricular lead placement was successful using standard guidewires with broad curvatures. Satisfactory acute and follow-up stimulation thresholds and sensing were obtained with the only complication being an intraoperative lead dislodgement, prompting a second ventricular lead. Successful transvenous lead placement across a tricuspid annuloplasty ring is possible.
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3,320
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How to test mode switching in pacemakers implanted in patients: the MOST study.
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Optimal management of atrial arrhythmias with dual chamber pacemakers requires proper performance of automatic mode switching (AMS). The aim of this study was to develop a reliable technique to test the AMS function by using an external electronic device capable of mimicking the occurrence of supraventricular arrhythmias (Supraventricular Arrhythmia Simulator [SAS]). The SAS delivers low voltage pulse trains (200 mV, 20 ms) through two skin electrodes. Each pulse train lasts 15 seconds and starts synchronously with a pacing pulse of the implanted pacemaker to avoid interference from the operator. The pulse train rate is set at 350, 250, and 160 beats/min to simulate AF, atrial flutter, and atrial tachycardia (AT), respectively. Thirty-five patients implanted with Vitatron pacemakers, whose AMS system has been previously validated, were enrolled. Atrial and ventricular sensing were programmed in unipolar mode at 0.5 mV and in bipolar mode at > 2 mV, respectively. All pulses from the SAS were detected by the atrial channel at an amplitude ranging from 1 to 3 mV. The test proved to be safe and reliable at rest and during exercise. AMS occurred immediately at onset or at offset of atrial arrhythmias, and no adverse interference on pacemaker function was seen from the SAS. In conclusion, the described technique and the SAS are safe and reliable for patient and pacemaker function and can be proposed as a useful method to verify proper performance of AMS function irrespective of the type of implanted devices.
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3,321
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Delayed cardioprotective effects of exercise in dogs are aminoguanidine sensitive: possible involvement of nitric oxide.
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Dogs were subjected to exercise on a treadmill, using a protocol in which the speed and slope were increased every 3 min, and which elevated both heart rate (to a mean of 198+/-14 beats.min(-1)) and mean arterial blood pressure (to 150+/-4 mmHg). Then, 24 or 48 h later, the dogs were anaesthetized with a mixture of alpha-chloralose and urethane and subjected to a 25 min occlusion of the left anterior descending coronary artery. The control dogs (instrumented but not exercised) were subjected to the same procedure. In some dogs the nitric oxide synthase inhibitor aminoguanidine (50 mg.kg(-1); intravenous) was administered 30 min before occlusion. Baroreflex sensitivity (BRS) was determined by the rapid bolus injection of phenylephrine 60 min before, and again 3 min after, the onset of occlusion. Exercise markedly reduced the consequences of coronary artery occlusion 24 h (but not 48 h) later, without modifying myocardial tissue blood flow. In the exercised dogs there were reductions in arrhythmia severity [ventricular fibrillation (VF) during occlusion, 0%; survival from the combined ischaemia/reperfusion insult, 70%] compared with controls (VF during occlusion, 36%; survival, 9%). BRS was preserved during occlusion in the exercised dogs (before occlusion, 1.60+/-0.54 ms.mmHg(-1); 3 min after occlusion, 1.37+/-0.4 ms.mmHg(-1)), but not in controls (before occlusion, 1.28+/-0.29 ms.mmHg(-1); 3 min after occlusion, 0.45+/-0.12 ms.mmHg(-1); P<0.05), and other ischaemic changes (inhomogeneity of electrical activation and changes in the ST-segment, recorded over the ischaemic region) were also less marked in the exercised dogs. Exercise-induced cardioprotection was abolished by aminoguanidine (VF during occlusion, 25%; survival, 0%). The results show that even a single period of exercise affords delayed protection against ischaemia/reperfusion-induced VF and other ischaemic changes. Since this protection is abolished by aminoguanidine, and since (inducible) NO synthase activity was elevated 3-fold in left ventricular samples 24 h after exercise, we suggest that this protection is mediated by nitric oxide.
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3,322
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Clinical value of left atrial appendage flow velocity for predicting of cardioversion success in patients with non-valvular atrial fibrillation.
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Echocardiographic parameters for predicting cardioversion outcome in patients with non-valvular atrial fibrillation are not accurately defined.</AbstractText>To evaluate the role of left atrial appendage flow velocity detected by transoesophageal echocardiography for prediction of cardioversion outcome in patients with non-valvular atrial fibrillation enrolled in a prospective. multicentre, international study.</AbstractText>Four hundred and eight patients (257 males, mean age: 66 +/- 10 years) with non-valvular atrial fibrillation lasting more than 48 h but less than 1 year underwent transthoracic echocardiography and transoesophageal echocardiography before either electrical (n=324) or pharmacological (n=84) cardioversion.</AbstractText>Cardioversion was successful in restoring sinus rhythm in 328 (80%) and unsuccessful in 80 patients (20%). Mean left atrial appendage peak emptying flow velocity was significantly higher in patients with successful than in those with unsuccessful cardioversion (32.4 +/- 17.7 vs 23.5 +/- 13.6 cm x s(-1); P<0.0001). At multivariate logistic regression analysis, three parameters proved to be independent predictors of cardioversion success: the atrial fibrillation duration <2 weeks (P=0.011, OR=4.9, CI 95%=1.9-12.7), the mean left atrial appendage flow velocity >31 cm x s(-1) (P=0.0013, OR=2.8, CI 95%=1.5-5.4) and the left atrial diameter <47 mm (P=0.093, OR=2.0, CI 95%=1.2-3.4). These independent predictors of cardioversion success outperformed other univariate predictors such as left ventricular end-diastolic diameter <58 mm, ejection fraction >56% and the absence of left atrial spontaneous echo contrast.</AbstractText>In patients with non-valvular atrial fibrillation, measurement of the left atrial appendage flow velocity profile by transoesophageal echocardiography before cardioversion provides valuable information for prediction of cardioversion outcome.</AbstractText>
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3,323
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Antiarrhythmic effect of nifekalant on atrial tachyarrhythmia in four patients with severe heart failure.
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Nifekalant is a class III antiarrhythmic drug, which prolongs the refractory period of the atrial and ventricular myocardium, without negative inotropic action. Intravenous nifekalant was administered in four patients with atrial tachyarrhythmia and severe heart failure to terminate or prevent atrial tachyarrhythmia.</AbstractText>Two of three episodes of atrial tachyarrhythmia were terminated by intravenous nifekalant (0.22 to 0.30 mg/kg) administration. Continuous intravenous infusion of nifekalant (0.15 to 0.40 mg/kg/hr) during six episodes to maintain the sinus rhythm, prevented recurrence of atrial tachyarrhythmia in five episodes in which prolongation of the QTc interval was observed to more than 450 msec. None of the patients showed worsening of the hemodynamics during treatment. One patient developed polymorphic ventricular tachycardia, which deteriorated into ventricular fibrillation.</AbstractText>Nifekalant may be effective for treating atrial tachyarrhythmia in patients with severe heart failure. Further clinical studies are needed to confirm these findings.</AbstractText>
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3,324
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Mechanisms of ventricular fibrillation during coronary angioplasty: increased incidence for the small orifice caliber of the right coronary artery.
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Ventricular fibrillation (VF) is not an infrequent complication of percutaneous transluminal coronary angioplasty (PTCA). However, it is not clear why there is a marked discrepancy in the higher incidence of VF during right coronary artery (RCA) approach.</AbstractText>We analyzed in detail every case of VF occurring in 905 consecutive PTCA procedures to investigate possible mechanisms. Sixteen patients (M/F=15/1, mean age: 71 +/- 8 years) with VF during PTCA for the RCA as Group I. Those 51 patients (M/F=48/3, mean age: 70 +/- 9 years) without VF during PTCA for the RCA engagement were designated as Group II. Patients were equipped with cardiac event recorder (CardioCall, Reynolds Medical, UK) before the PTCA, and we set the time period 1 min before and after the event. The lead II was selected to check the QRS width, QTc interval, ST segment change and RR interval before and after event. A total of 905 PTCA procedures were included. There were 561 procedures for the left coronary artery and three events (0.5%) with spontaneous VF. However, there were 16 events (4.6%) of VF during 344 PTCA procedures for the right coronary artery. The incidence of VF for the right side PTCA was significantly higher than for the left side. The orifice of RCA in Group I was smaller than Group II (orifice of RCA in Group I vs. Group II - 2.7+/-0.8 vs. 4.1+/-1.2 mm, P<0.001). Most cases (68.7%) presented with ST segment depression before the onset of VF.</AbstractText>A small caliber of RCA and associated ST segment changes played important roles in the patients with VF during the PTCA.</AbstractText>
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3,325
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Combination IK1 and IKr channel blockade: no additive lowering of the defibrillation threshold.
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Selective blockade of the inward rectifier potassium channel I(K1) by barium, or of the rapidly activating delayed rectifier potassium channel I(Kr) by D,L-sotalol, prolongs repolarization and reduces the defibrillation threshold (DFT). This study hypothesized that combination I(K1) and I(Kr) channel block would produce concentration-dependent additive effects on DFT and ventricular refractoriness. A range of barium and D,L-sotalol concentrations, alone and in combination, were examined with respect to DFT, ventricular effective refractory period (VERP), and ventricular fibrillation cycle length (VFCL) in 133 Langendorff-perfused rabbit hearts. Barium produced a concentration-dependent reduction of DFT (-49+/-4%), with concentration-dependent increases in VERP (26+/-6%) and VFCL (42+/-18%). D,L-Sotalol produced a concentration-dependent lowering of DFT (-53+/-6%) with a concentration-dependent increase in VFCL (34+/-8%) but not VERP. Low (1.6 microM), intermediate (3.1 microM), and high (12.5 microM) barium concentrations combined with varying D,L-sotalol concentrations produced equal or smaller decreases in DFT compared with corresponding doses of barium or D,L-sotalol alone. Except at the lowest concentrations of barium (1.6 and 3.1 microM) (p < 0.05), there was no significant additive interaction between barium and D,L-sotalol on VERP or VFCL. Combination I(K1) and I(Kr) channel block by barium and D,L-sotalol does not produce additive reduction of DFT.
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3,326
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Idiopathic eosinophilic endomyocarditis in the absence of peripheral eosinophilia.
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In this case report we present two patients with unusual manifestations of eosinophilic endomyocarditis: A 69-year-old patient with a history of heart failure and ventricular fibrillation and a 16-year-old woman with ventricular fibrillation and an ECG indicating acute myocardial infarction had both normal blood eosinophil counts at the onset of symptoms. The absence of hypereosinophilia, therefore, does not exclude the presence of eosinophilic organ infiltration. Endomyocardial biopsy may be the only diagnostic procedure to identify necrotic eosinophilic endomyocarditis in patients with unexplained heart failure or ventricular fibrillation.
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3,327
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Single chamber ventricular compared with dual chamber pacing: a review.
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Since its introduction in the 1950s, the cardiac pacemaker has become increasingly sophisticated in an attempt to mimic normal cardiac physiology. Rapidly evolving pacing technology has seen pacemakers evolve from crude, fixed-rate, single chamber ventricular devices to dual chamber rate-adaptive units. While there is indirect evidence that supports the use of dual chamber pacing in the vast majority of patients, it is still unclear whether these newer, more expensive devices afford a significant morbidity and mortality benefit over single-chamber, ventricular, rate-adaptive pacemakers. A review of three large, randomized trials failed to demonstrate a clear benefit of dual chamber or atrial-based pacing over single chamber ventricular pacing for the majority of cardiovascular outcomes (heart failure, stroke and mortality), with the possible exception of atrial fibrillation. Information is also needed on the potential protective effects of atrial-based pacing over dual chamber pacing in elderly patients with sinus node dysfunction. Longer follow-up periods may be necessary to determine whether there are any mortality benefits associated with dual chamber pacing. Additional confirmation of benefits of dual chamber pacing may be provided by other ongoing prospective trials.
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3,328
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Amiodarone as compared with lidocaine for shock-resistant ventricular fibrillation.
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Lidocaine has been the initial antiarrhythmic drug treatment recommended for patients with ventricular fibrillation that is resistant to conversion by defibrillator shocks. We performed a randomized trial comparing intravenous lidocaine with intravenous amiodarone as an adjunct to defibrillation in victims of out-of-hospital cardiac arrest.</AbstractText>Patients were enrolled if they had out-of-hospital ventricular fibrillation resistant to three shocks, intravenous epinephrine, and a further shock; or if they had recurrent ventricular fibrillation after initially successful defibrillation. They were randomly assigned in a double-blind manner to receive intravenous amiodarone plus lidocaine placebo or intravenous lidocaine plus amiodarone placebo. The primary end point was the proportion of patients who survived to be admitted to the hospital.</AbstractText>In total, 347 patients (mean [+/-SD] age, 67+/-14 years) were enrolled. The mean interval between the time at which paramedics were dispatched to the scene of the cardiac arrest and the time of their arrival was 7+/-3 minutes, and the mean interval from dispatch to drug administration was 25+/-8 minutes. After treatment with amiodarone, 22.8 percent of 180 patients survived to hospital admission, as compared with 12.0 percent of 167 patients treated with lidocaine (P=0.009; odds ratio, 2.17; 95 percent confidence interval, 1.21 to 3.83). Among patients for whom the time from dispatch to the administration of the drug was equal to or less than the median time (24 minutes), 27.7 percent of those given amiodarone and 15.3 percent of those given lidocaine survived to hospital admission (P=0.05).</AbstractText>As compared with lidocaine, amiodarone leads to substantially higher rates of survival to hospital admission in patients with shock-resistant out-of-hospital ventricular fibrillation.</AbstractText>
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3,329
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Differential effects of sarcolemmal and mitochondrial K(ATP) channels activated by 17 beta-estradiol on reperfusion arrhythmias and infarct sizes in canine hearts.
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We have demonstrated the effects of estrogen on modulation of ATP-sensitive K(+) channels; however, the subcellular location of these channels is unknown. The purpose of the present study was to investigate the role of the sarcolemmal and mitochondrial ATP-sensitive K(+) channels in a canine model of myocardial infarction after stimulation with 17 beta-estradiol. Anesthetized dogs were subjected to 60 min of the left anterior descending coronary artery occlusion followed by 3 h of reperfusion. Infarct size was markedly reduced in estradiol-treated dogs compared with controls (14 +/- 6 versus 42 +/- 6%, P < 0.0001), indicating the effective dose of estradiol administrated. Pretreatment with the mitochondrial ATP-sensitive K(+) channel antagonist 5-hydroxydecanoate completely abolished estradiol-induced cardioprotection. The sarcolemmal ATP-sensitive K(+) channel antagonist 1-15-12-(5-chloro-o-anisamido)ethyl-methoxyphenyl)sulfonyl-3-methylthiourea (HMR 1098) did not significantly attenuate estradiol-induced infarct size limitation. In addition, estradiol administration significantly reduced the incidence and duration of reperfusion-induced ventricular tachycardia and ventricular fibrillation. Although 5-hydroxydecanoate alone caused no significant effect on the incidence of reperfusion arrhythmias in the presence or absence of estradiol, the administration of HMR 1098 abolished estrogen-induced improvement of reperfusion arrhythmias. Pretreatment with the estrogen-receptor antagonist faslodex (ICI 182,780) did not alter estrogen-induced infarct-limiting and antiarrhythmic effects. These results demonstrate that estrogen is cardioprotective against infarct sizes and fatal reperfusion arrhythmias by different ATP-sensitive K(+) channels for an estrogen receptor-independent mechanism. The infarct size-limiting and antiarrhythmic effects of estrogen were abolished by 5-hydroxydecanoate and HMR 1098, suggesting that the effects may result from activation of the mitochondrial and sarcolemmal ATP-sensitive K(+) channels, respectively.
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3,330
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Altered cardiovascular responses in mice lacking the M(1) muscarinic acetylcholine receptor.
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Although the M(2) muscarinic acetylcholine receptor (mAChR) is the predominant functional mAChR subtype in the heart, some responses of the cardiovascular system to acetylcholine (ACh) may be mediated by other mAChR subtypes. The potential effect of M(1) mAChR on heart function was investigated using M(1) knockout (M(1)-KO) mice. In vivo cardiodynamic analysis showed that basal values of heart rate (HR), developed left ventricular pressure (DLVP), left ventricular dP/dt(max) (LV dP/dt(max)), and mean blood pressure (MBP) were similar between wild-type (WT) and M(1)-KO mice. Injection of the putative M(1)-selective agonist 4-(m-chlorophenyl-carbamoyloxy)-2-butynyltrimethylammonium (McN-A-343) produced an increase in LV dP/dt(max), DLVP, HR, and MBP in WT mice but did not affect hemodynamic function in the M(1)-KO mice. The stimulatory effect of McN-A-343 in WT mice was blocked by pretreatment with propranolol, indicating that stimulation of the M(1) mAChRs on sympathetic postganglionic neurons evoked release of catecholamines. Intravenous injection of ACh in both WT and M(1)-KO mice caused atrioventricular conduction block, without a significant change in the frequency of atrial depolarization, or atrial fibrillation. Immunoprecipitation and reverse transcriptase-polymerase chain reaction failed to detect the expression of M(1) mAChR in cardiac tissue from WT mice. The carbachol-induced increase of phospholipase C activity in cardiac tissues was not different between WT and M(1)-KO mice. These results demonstrate that 1) activation of M(1) mAChR subtype on sympathetic postganglionic cells results in catecholamine-mediated cardiac stimulation, 2) M(1) mAChR is not expressed in mouse heart, and 3) administration of ACh to mice induces arrhythmia.
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3,331
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An evaluation of coronary artery bypass grafting without aortic cross-clamping due to severely atherosclerotic ascending aorta.
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We evaluated coronary artery bypass grafting (CABG) in which aortic cross-clamping is not done due to severe atherosclerosis of the ascending aorta.</AbstractText>Subjects were 51 patients undergoing CABG without aortic cross-clamping during cardiopulmonary bypass under moderately hypothermic ventricular fibrillation in the 12 years from June 1988 to October 1999 (Group N). In some cases, empty beating or moderate hypothermic circulatory arrest was used. We compared these 51 with 1104 subjects undergoing conventional CABG with aortic cross-clamping and cardioplegic cardiac arrest in the 9 years from June 1988 to December 1997 (Group A).</AbstractText>In all 6 cases with neurologic deficits, moderately hypothermic circulatory arrest was used during proximal anastomosis of saphenous vein grafts. Postoperative computed tomography scan showed them to have suffered infarction due to embolization. Multivariate analysis identified proximal saphenous vein grafting under moderately hypothermic circulatory arrest as a predictor of neurologic deficit. Complete revascularization was significantly lower in Group N. Actual survival and freedom from cardiac death were significantly lower in Group N.</AbstractText>Manipulation of the atherosclerotic ascending aorta under moderately hypothermic circulatory arrest or ventricular fibrillation generates the highest risk of perioperative neurologic deficit and should thus be avoided. In-situ arterial grafting should be conducted with utmost care.</AbstractText>
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3,332
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Effects of different preproendothelin-1 mRNA anti-sense oligodeoxynucleotides on ischemic arrhythmias in rats.
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The effects of four anti-sense oligodeoxynucleotides (AS-ODNs) against rat or human preproendothelin-1 mRNA on ischemic arrhythmias in anesthetized rats were studied. AS-ODN (60 nmol/kg) or control (normal saline; sense-ODN, and scrambled-ODN, 60 nmol/kg) was injected 2 h before acute myocardial ischemia elicited by the occlusion of the left anterior descending coronary artery. Arrhythmias during 60-min ischemia were assessed, and plasma endothelin-1 was determined with an endothelin-1-specific radioimmunoassay system. The results showed that anti-senses against human preproendothelin-1 mRNA were anti-arrhythmic without significant impact on hemodynamics, whereas two against rat preproendothelin-1 mRNA and the three controls failed to be anti-arrhythmic. In human antisense groups, both the incidence of reversible ventricular fibrillation and the mortality were decreased to zero. The incidences of ventricular tachycardia and salvos were significantly decreased from almost 100% in the controls to < or =30% (p < 0.01), the arrhythmia score from an average of approximately 3.6 to 0 and 0.7, respectively (p < 0.01 versus controls), and the total ventricular ectopic beats from an average of 307-338 to < 40 (p < 0.01). The human AS-ODNs led to less plasma endothelin-1, which was associated with suppressed ischemic arrhythmias in this rat model, indicating a contributory role of endothelin-1 in ischemic arrhythmias. Conversely, considering the two- or three-base mismatches between the human AS-ODNs and rat preproendothelin-1 mRNA, and the failure of the rat AS-ODNs in suppressing arrhythmias, the possibility could not be excluded that human endothelin-1 AS-ODNs acted via an undetermined pathway other than endothelin-1.
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3,333
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Novel electrophysiologic parameter of dispersion of atrial repolarization: comparison of different atrial pacing methods.
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Heterogeneity of ventricular repolarization plays a major role in reentrant tachyarrhythmias in cardiac tissue. However, the role of atrial repolarization added activation time (AT) to refractoriness in atrial vulnerability has not been investigated in detail.</AbstractText>The study population consisted of 34 patients: 18 with atrial fibrillation (AF) and 16 without AF (control group). The effective refractory periods (ERPs) in the right atrial appendage, low lateral right atrium, high right septum, and distal coronary sinus, and ATs from P wave onset to each electrogram during sinus rhythm and right atrial appendage, low lateral right atrial, high right septal, distal coronary sinus, and biatrial pacing were measured. Atrial recovery time, defined as the sum of AT and ERP, and its dispersions during sinus rhythm, right atrial appendage, low lateral right atrial, high right septal, distal coronary sinus, and biatrial pacing were calculated. Both ERP dispersion and atrial recovery time dispersion during sinus rhythm were significantly greater in the AF group than in the control group. Atrial recovery time dispersion during distal coronary sinus, high right septal, or biatrial pacing was significantly smaller than that during right atrial appendage or low lateral right atrial pacing in each group. In particular, atrial recovery time dispersion during distal coronary sinus pacing was the smallest of the five pacing methods in the AF group. P wave duration during biatrial or high right septal pacing was significantly shorter than during right atrial appendage, low lateral right atrial, or distal coronary sinus pacing in each group.</AbstractText>Atrial recovery time dispersion is suitable as an electrophysiologic parameter of atrial vulnerability. Distal coronary sinus pacing may prevent AF by increasing homogeneity of atrial repolarization, whereas biatrial and high right septal pacing contribute not only homogeneity of atrial repolarization but also improvement of atrial depolarization.</AbstractText>
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3,334
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[The best of 2001. Echocardiography].
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The year 2001 will be characterised by the confirmation of the essential place of harmonic imaging in echocardiography, a technique which has improved in a very important fashion the definition of the endocardial contour, thus giving a more reliable analysis of the segment kinetics, as much at rest as during a physical or pharmacological stress. The advances in the field of stress echocardiography essentially give confirmation of the excellent prognostic value of this technique, either post-infarction or in chronic coronary disease, including hypertensive patients, and with left ventricular hypertrophy or a conduction disorder. The aspirations of a more quantitative approach to regional myocardial function with the aid of myocardial tissue Doppler have been partly confirmed, even if no simple parameter can yet provide information of the presence of myocardial segment viability or ischaemia. The contribution of Doppler echocardiography in the unraveling of left ventricular diastolic insufficiency is crucial, with the description of parameters allowing characterisation of the type of left ventricular diastolic function anomaly and non-invasive evaluation of the filling pressures. The advances in transoesophageal echocardiography have essentially provided a better characterisation of the thrombo-embolic risk markers in atrial fibrillation and in the search for a cardiac source of embolus. Valuable information has equally been provided in acute aortic pathology particularly in the description of symptomatology and evolution of isthmic ruptures of the aorta. The first images of transthoracic echocardiography with real time three-dimensional reconstruction have finally been presented, allowing a glimpse of the enormous possibilities of this method, compared to recorded reconstruction which is routinely performed, especially in transoesophageal echocardiography. Though myocardial contrast echocardiography continues to induce very many fundamental publications, the clinical applications are slow to convince, facing the difficulties of proposing an adequate treatment and standardising the image, and an interpretation which takes account of physiological parameters (coronary micro-circulation).
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3,335
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[The best of 2001. Arrhythmia].
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Among the classic problems of rhythmology, which can be classified topographically into atrial rhythm disturbances, junctional rhythm disturbances and ventricular rhythm disturbances, it is certainly the atrial rhythm disorders, including atrial fibrillation, which constitute the "final frontier". Population aging comes with an indisputable increase in the incidence of this arrhythmia, which poses not only classic therapeutic problems (is it better to correct the fibrillation or to be content with slowing it) but also new ones (pulmonary vein tissue ablation for example). It is still very difficult to make a choice among the quantity of ideas and new techniques proposed in rhythmology. From the publications appearing in 2001 in the New England Journal of Medicine, the leading clinical journal, we contemplate topical issues this year concerning three principle subjects: the treatment of atrial fibrillation yet again, arrhythmias of genetic origin, and ventricular rhythm disturbances in the era of the implantable defibrillator.
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3,336
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[Contribution of the implantable ECG monitor in the etiologic diagnosis of syncope and unexplained recurrent syncopal attacks. Initial experience with 32 patients].
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Following an exhaustive aetiological investigation, 10 to 26% of syncopal attacks remain unexplained. In these cases the correlation between symptoms and rhythm is a deciding step for the aetiological diagnosis. We report our initial experience using an implantable electrocardiographic monitor, a new diagnostic tool in patients suffering from syncope and recurrent unexplained syncopal attacks.</AbstractText>The study included 32 patients (average age 55 +/- 22 years; 23 males) suffering from syncope and/or recurrent syncopal attacks remaining unexplained following an exhaustive aetiological investigation. The average follow up was 10.2 +/- 2.5 months. No case of sudden death was registered, and the device was removed in only one patient due to poor tolerance. During follow up, 21 recordings were memorized and analysed in 15 patients (45%), giving an average of 1.4 recordings per patient. The average interval for recurrence of symptoms after implantation was from 84 +/- 104 days, 75% of the episodes coming in the first 2 months following implantation. An arrhythmia was detected on 10 occasions: a malignant ventricular arrhythmia in 2 patients, a non-sustained ventricular tachycardia in 1 patient, a junctional tachycardia in 1 patient, entry into paroxysmal atrial fibrillation in 4 patients, a sinus bradycardia in 1 patient, and a sinus pause for 19 seconds in 1 patient. In one patient ST segment depression was documented following anterior chest pain. The tracing was normal with sinus rhythm recorded on 10 occasions, representing the only documented information in 4 patients. In total, an aetiology was found in 11 of the 32 patients evaluated (34%). Once the aetiological diagnosis was established and a specific treatment initiated, all the patients became asymptomatic.</AbstractText>Our preliminary results underline the significance of the implantable ECG monitor in the diagnostic approach to recurrent unexplained syncopal attacks. The exact place of this tool in the decisional algorithm for syncope remains to be defined with further studies.</AbstractText>
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3,337
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Natural history of Brugada syndrome: insights for risk stratification and management.
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Treatment of patients with Brugada syndrome is complicated by the incomplete information on the natural history of the disease related to the small number of cases reported. Furthermore, the value of programmed electrical stimulation (PES) for risk stratification is highly debated. The objective of this study was to search for novel parameters to identify patients at risk of sudden death.</AbstractText>Clinical data were collected for 200 patients (152 men, 48 women; age, 41+/-18 years) and stored in a dedicated database. Genetic analysis was performed, and mutations on the SCN5A gene were identified in 28 of 130 probands and in 56 of 121 family members. The life-table method of Kaplan-Meier used to define the cardiac arrest-free interval in patients undergoing PES failed to demonstrate an association between PES inducibility and spontaneous occurrence of ventricular fibrillation. Multivariate Cox regression analysis showed that after adjusting for sex, family history of sudden death, and SCN5A mutations, the combined presence of a spontaneous ST-segment elevation in leads V1 through V3 and the history of syncope identifies subjects at risk of cardiac arrest (HR, 6.4; 95% CI, 1.9 to 21; P<0.002).</AbstractText>The information on the natural history of patients obtained in this study allowed elaboration of a risk-stratification scheme to quantify the risk for sudden cardiac death and to target the use of the implantable cardioverter-defibrillator.</AbstractText>
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3,338
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Class I antiarrhythmic drug and coronary vasospasm-induced T wave alternans and ventricular tachyarrhythmia in a patient with Brugada syndrome and vasospastic angina.
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A 50-year-old man presented with a history of transient chest pain and palpitations. The 12-lead ECG at rest showed normal sinus rhythm. A slight ST segment elevation was observed in leads V1 to V3. During hospitalization, atrial fibrillation developed, and oral pilsicainide was administered. Thirty minutes after the drug was given, the ECG showed marked ST segment elevation in leads V1 to V3, and T wave alternans became visible in leads V2 and V3. Self-terminating ventricular tachycardia was initiated following frequent ventricular premature complexes, which showed a left bundle branch block pattern. The coronary angiogram was normal, but in the provocation test of vasospastic angina, acetylcholine administration into the left coronary artery resulted in complete occlusion of the left anterior descending and circumflex arteries. Marked ST segment elevation developed in leads I, aVL, and V3 to V6 concomitant with visible QT/T alternans in leads V4 and V5, and ventricular tachyarrhythmia was initiated. Brugada syndrome and vasospastic angina coexisted in this patient, and T wave alternans can be used as a predictor of ventricular tachyarrhythmias in such patients.
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3,339
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Analysis of troponin I levels after spontaneous implantable cardioverter defibrillator shocks.
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Serum cardiac troponin I (cTnI) is a sensitive and specific marker for myocardial injury. Myocardial ischemia and/or injury can be a trigger for ventricular arrhythmias. The aim of this study was to assess the frequency and significance of elevated serum cTnI levels after spontaneous implantable cardioverter defibrillator (ICD) shocks.</AbstractText>Serial cTnI measurements and ECGs were performed in 35 patients with transvenous ICDs who were admitted after spontaneous ICD shocks. Elevated cTnI levels were found in 18 patients (51%). Acute coronary syndrome was diagnosed in 5 (22%) of 23 patients with known coronary artery disease. After excluding the patients with acute coronary syndrome, elevated cTnI levels were present in 13 (43%) of 30 patients: 18% of patients with < or =3 shocks and 58% of patients with >3 shocks. Patients with elevated cTnI levels received a higher number of shocks (16+/-18 vs 5+/-7; P < 0.05) and had higher total delivered energies (475+/-538 J vs 128+/-184 J; P < 0.05) compared with patients with normal cTnI. Patients with acute coronary syndrome had higher peak cTnI levels (18+/-16 ng/mL) compared with patients with elevated cTnI without acute coronary syndrome (3.8+/-4.3 ng/mL; P < 0.01).</AbstractText>Serum cTnI rises occur in the majority of patients after multiple (>3) spontaneous ICD discharges but are due to acute coronary syndrome only 14% of the time (22% of the time in patients with known coronary artery disease).</AbstractText>
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3,340
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[Atrial fibrillation: always cardioversion? No].
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Two major treatment strategies have emerged in the management of patients with atrial fibrillation (AF): restoration of sinus rhythm and antiarrhythmic drug prophylaxis versus ventricular rate control and chronic anticoagulation. Besides the potential benefits of the restoration of sinus rhythm, several considerations support the choice of controlling the heart rate, mainly the poor efficacy of antiarrhythmic drug prophylaxis. The decision of pursuing the AF cardioversion should be based mainly on the importance of sinus rhythm restoration and the probability of sinus rhythm maintenance. The factors conditioning the maintenance of sinus rhythm following cardioversion are the duration of AF, cardiac size and function, underlying heart disease, the NYHA functional class, and the timing and number of AF recurrences. At least one attempt at cardioversion is warranted in the majority of patients with a first ever episode of AF; however, it seems advisable to give up even the first attempt at cardioversion in the mildly symptomatic patients who are very old, in patients with AF episodes dating back more than 24-36 months and in those with severe valvular heart disease or severe left ventricular dysfunction. A repeated attempt at cardioversion is usually indicated at the first recurrence of AF; repeated cardioversion seems unadvisable in patients with long-standing AF and early recurrence, in case of failure of amiodarone prophylaxis or of side effects of antiarrhythmic drugs, and when the patient is inclined not to undergo a new electrical cardioversion procedure. In patients with further recurrences of AF it is convenient to give up the cardioversion in case of mild symptoms, of failure of several antiarrhythmic drug regimens and when the withdrawal of oral anticoagulant therapy following sinus rhythm restoration is not safe. With regard to mortality, morbidity, quality of life and cost-effectiveness, the strategy of choice has not yet been established. Several large prospective randomized clinical trials comparing cardioversion and antiarrhythmic prophylaxis versus ventricular rate control are ongoing. The results of these studies could, in the near future, provide useful indications for the choice of the therapeutic regimen to be employed.
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3,341
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Proarrhythmic effects of adenosine: one decade of clinical data.
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In 1989, adenosine was introduced into the American clinical setting as an antiarrhythmic drug for the acute management of reentrant supraventricular tachycardia involving the atrioventricular node. During this decade of use, evidence for proarrhythmic effects of the drug have been documented. In addition to the mostly benign transient episodes of atrial fibrillation, several cases of life-threatening ventricular arrhythmias induced by adenosine have been reported. This article summarizes the proarrhythmic effects of adenosine as they were reported in the literature as well as data from the manufacturer files. The causes of these adverse effects of adenosine are analyzed, and factors to be considered before using the drug are discussed.
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3,342
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Does heart rate identify sudden death survivors? Assessment of heart rate, QT interval, and heart rate variability.
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The objective was to test whether the circadian variability of several electrocardiographic variables distinguishes sudden cardiac death survivors from heart disease patients without a history of cardiac arrest and from normal subjects. Heart rate, heart rate variability, and QT interval have been reported to identify survivors of sudden cardiac death. Computer-assisted continuous QT measurement and heart rate variability analysis were performed on 24-hour Holter records for three groups: (1) 14 sudden death survivors; (2) 14 control patients with diagnosis and therapy matched to survivors; and (3) 14 healthy subjects. There were no significant differences in 24-hour mean RR and QT intervals between groups. However, heart rate was significantly different between the three groups at night but not during the day because the expected nighttime decline was markedly blunted in survivors and somewhat blunted in control patients. The QT interval and frequency domain heart rate variability measures followed a similar circadian pattern. The mean QTc was significantly longer in control patients. The QTc had a wide range in all groups, but less in sudden death survivors. Of ten common time and frequency domain heart rate variability indices, only SDANN and SDNN were significantly lower in sudden death survivors. Reduced circadian variation of heart rate, with marked blunting of the nighttime heart rate decline, identifies sudden cardiac death survivors as well as does SDANN and SDNN, and, in contrast to heart rate variability measures, can easily be obtained from a Holter report without complex calculations.
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3,343
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Correlates of left atrial size in hypertensive patients with left ventricular hypertrophy: the Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) Study.
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Left ventricular hypertrophy has been suggested to mediate the relation between hypertension and left atrial enlargement, with associated risks of atrial fibrillation and stroke. However, less is known about correlates of left atrial size in hypertensive patients with left ventricular hypertrophy. We assessed left atrial size by echocardiography in 941 hypertensive patients, age 55 to 80 (mean, 66) years, with electrocardiographic left ventricular hypertrophy at baseline in the Losartan Intervention For Endpoint reduction in hypertension study. Enlarged left atrial diameter (women, >3.8 cm; men, >4.2 cm) was present in 56% of women and 38% of men (P<0.01). Compared with the 512 patients with normal left atrial size, the 429 patients with enlarged left atrium more often had mitral regurgitation, atrial fibrillation, and echocardiographic left ventricular hypertrophy. They also had higher age, systolic blood pressure, pulse pressure, weight, body mass index, left ventricular internal chamber dimension, stroke volume, and mass and lower relative wall thickness and ejection fraction (all, P<0.05). In logistic regression analysis, left atrial enlargement was related to left ventricular hypertrophy and eccentric geometry; greater body mass index, systolic blood pressure, and age; female gender; mitral regurgitation; and atrial fibrillation (all, P<0.05). Thus, left atrial size in hypertensive patients with electrocardiographic left ventricular hypertrophy is influenced by gender, age, obesity, systolic blood pressure, and left ventricular geometry independently of left ventricular mass and presence of mitral regurgitation or atrial fibrillation.
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3,344
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Phase I trial of the histone deacetylase inhibitor, depsipeptide (FR901228, NSC 630176), in patients with refractory neoplasms.
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The primary objectives of this trial were to define the maximum tolerated dose (MTD) and to characterize the toxicities and pharmacokinetics of depsipeptide (FR901228) given on a day-1 and day-5 schedule every 21 days. A secondary objective of the trial was to seek evidence of antineoplastic activity.</AbstractText>Patients with advanced or refractory neoplasms received depsipeptide by a 4-h i.v. infusion on days 1 and 5 of a 21-day cycle. On the basis of preclinical data suggesting that depsipeptide may have significant cardiac toxicity, patients were treated while receiving continuous cardiac monitoring and were followed with serial cardiac enzyme determinations, electrocardiograms (ECGs), and nuclear ventriculograms (MUGA scans). The starting dose of the trial was 1 mg/m(2), and dose escalations proceeded through a total of eight dose levels to a maximum of 24.9 mg/m(2). Toxicities were graded using the National Cancer Institute common toxicity criteria, and pharmacokinetics were determined using a liquid chromatography/tandem mass spectrometry method.</AbstractText>Patients (37) received a total of 88 cycles of treatment on study (range: one to eight cycles). Dose-limiting toxicity (DLT) was observed, and the MTD exceeded at a dose of 24.9 mg/m(2). The DLTs included grade-3 fatigue (3 patients), grade-3 nausea and vomiting (1 patient), grade-4 thrombocytopenia (2 patients), and grade-4 cardiac arrhythmia (1 patient, atrial fibrillation). The MTD was defined at the seventh dose level (17.8 mg/m(2)). Reversible ST/T changes and mild reversible dysrhythmias were observed on the post-treatment ECG. There were no clinically significant changes in left ventricular ejection fraction. One patient achieved a partial response. The plasma disposition of depsipeptide was well described by a first-order, two-compartment model. The mean volume of distribution, clearance, t(1/2alpha) and t(1/2beta) at a dose of 17.8 mg/m(2) was: 8.6 liters/m(2), 11.6 liters/h/m(2), 0.42 h, and 8.1 h, respectively. The mean maximum plasma concentration at the MTD was 472.6 ng/ml (range: 249-577.8 ng/ml). Biological assays showed that the serum levels achieved could cause the characteristic cell cycle effects of this agent when serum was added to PC3 cells in culture, as well as increased histone acetylation in patient-derived peripheral blood mononuclear cells.</AbstractText>The MTD of depsipeptide given on a day-1 and -5 schedule every 21 days is 17.8 mg/m(2). The DLTs are fatigue, nausea, vomiting, and transient thrombocytopenia and neutropenia. Whereas cardiac toxicity was anticipated based on preclinical data, there was no evidence of myocardial damage. However, reversible ECG changes with ST/T wave flattening were regularly observed. Biologically active serum concentrations were achieved, and 1 patient obtained a partial response. The recommended Phase II dose is 17.8 mg/m(2) administered on day 1 and 5 of a 21-day cycle.</AbstractText>
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3,345
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[New guidelines for basic and advanced resuscitation of adults and children].
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We present the latest changes in the guidelines for resuscitation from the International Liaison Committee on Resuscitation (ILCOR). Defibrillation performed by non-medical personnel is more strongly endorsed than before. In unintubated patients the ventilation-to-compression ratio should always be 2:15. With a foreign body in the airway of an unconscious patient, compressions should be performed instead of the Heimlich manoeuvre. Amiodarone 300 mg intravenously is the first choice in refractory ventricular fibrillation or ventricular tachycardia in adults. Intubation of children is only recommended when performed by experienced personnel. The use of drugs is less recommended than previously; albumin is not recommended for the newly born.
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3,346
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Isolated noncompaction of ventricular myocardium associated with fatal ventricular fibrillation.
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A female infant with isolated noncompaction of ventricular myocardium who developed ventricular tachyarrhythmia is described. Wolff-Parkinson-White syndrome was shown by electrocardiography. At 9 months of age, the patient suddenly developed cardiac arrest. Electrocardiography following resuscitation with DC cardioversion demonstrated sinus rhythm without delta wave. The QT interval was normal. Frequent premature ventricular captures caused ventricular fibrillation. DC cardioversion was necessary to terminate frequent attacks of ventricular fibrillation until the introduction of beta blockers and lidocaine. Two-dimensional echocardiogram confirmed the diagnosis of isolated non-compaction of ventricular myocardium. Three months later, the patient died of ventricular fibrillation during respiratory syncytial viral infection.
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3,347
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Plasma levels of brain natriuretic peptide increase in patients with idiopathic bilateral atrial dilatation.
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Idiopathic bilateral atrial dilatation (IBAD) is an extremely rare anomaly and is usually associated with atrial fibrillation. Plasma levels of atrial natriuretic peptide (ANP) have been shown to increase in patients with atrial fibrillation. However, secretion of ANP and brain natriuretic peptide (BNP) in patients with IBAD remains unclear. We investigated the clinical features of 9 patients with IBAD and 16 age- and sex-matched patients with lone atrial fibrillation (LAF). Plasma levels of ANP and BNP were measured, and echocardiographic parameters were followed. Left (LAV) and right atrial volumes (RAV) were significantly higher in patients with IBAD than in patients with LAF (both p < 0.01). There were no differences between patients with IBAD and LAF in other echocardiographic parameters. The percent increases in LAV and RAV in patients with IBAD exceeded those in patients with LAF (both p < 0.01). Plasma levels of BNP and the BNP/ANP ratios in patients with IBAD were significantly higher than those in patients with LAF (both p < 0.01), but there was no significant difference in plasma levels of ANP. Regarding the clinical course of the patients with IBAD compared with those with LAF, the atrial volume increased gradually, and plasma levels of BNP were significantly higher. These findings suggested that IBAD was not only influenced by long-term atrial fibrillation, but also by subclinical left ventricular dysfunction.
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3,348
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Purkinje involvement in arrhythmias after coronary artery reperfusion.
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Previous studies have indicated that the endocardium may be responsible for a large portion of ventricular tachycardia (VT) seen with reperfusion of ischemic myocardium. To evaluate the role of the Purkinje system in nonreentrant VT arising from the endocardium after reperfusion, the anterior descending coronary artery was occluded for 20 min and then reperfused in 23 dogs after instrumentation of the risk zone with 21 multipolar plunge needles. VT with focal Purkinje origin was defined as a focal endocardial VT with Purkinje potentials recorded before the earliest endocardial myopotential. A total of 19 VTs (mean cycle length 214 +/- 2 ms) were observed with 11 (58%) having focal Purkinje origin. Fifty-eight percent of the VTs degenerated to ventricular fibrillation, with occurrences of two or more independent foci per complex (seen in 7 of 11 compared with 1 of 8 nonsustained VTs). In conclusion, these data show that Purkinje tissue may be important in the genesis of reperfusion VT.
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3,349
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Metabolic causes and prevention of ventricular fibrillation during acute coronary syndromes.
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The mechanisms leading to ventricular fibrillation that occur during acute myocardial ischemia are ill understood. Whether primary ventricular fibrillation is due to a transient imbalance of electrolytes, an alteration of membrane permeability, electrical re-entry phenomena, or other factors, one overriding influence is the development of regional myocardial energy crises. Acute alteration in the balance of substrate supply may lead, during greatly reduced blood flow, to instability of myocardial electrical conduction with the development of re-entry circuits. An immediate response to the angor animi and initial symptoms of an acute coronary syndrome is a rapid and marked increase in catecholamine release, which leads to adipose tissue lipolysis with an acute increase in plasma free fatty acid concentrations, suppression of insulin activity, and a reduction in glucose uptake by the myocardium. The utilization of free fatty acids instead of glucose by the ischemic myocardium could precipitate regional oxygen or energy crises. Prevention therefore should focus on minimizing the catecholamine response and providing the myocardium with an optimum supply of energy substrates. Since catecholamines are inotropic, the aim should be to redress the imbalance of substrate availability by controlling adipose lipolysis with reduction of plasma free fatty acid concentrations, increasing the availability of glucose, or both. Other approaches include inhibition of acylcarnitine transport and manipulation of fatty acid intermediaries. To combat primary ventricular fibrillation, preventive treatment must be established within 6 to 10 hours of the onset of ischemia. There is already experimental and clinical evidence that antilipolytic drugs decrease the incidence of ventricular fibrillation, but their potential has not been explored extensively.
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3,350
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Slow inactivation in voltage-gated sodium channels: molecular substrates and contributions to channelopathies.
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Slow inactivation in voltage-gated sodium channels is a biophysical process that governs the availability of sodium channels over extended periods of time. Slow inactivation, therefore, plays an important role in controlling membrane excitability, firing properties, and spike frequency adaptation. Defective slow inactivation is associated with several diseases of cell excitability, such as hyperkalemic periodic paralysis, myotonia, idiopathic ventricular fibrillation and long-QT syndrome. These associations underscore the physiological importance of this phenomenon. Nevertheless, our understanding of the molecular substrates for slow inactivation is still fragmentary. This review covers the current state of knowledge concerning the molecular underpinnings of slow inactivation, and its relationship with other biophysical processes of voltage-gated sodium channels.
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3,351
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[Immediate postoperative arrhythmias follwing pneumonectomy for lung cancer].
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Immediate postoperative arrhythmias after pneumonectomy for non small cell lung cancer is a serious complication. Frequency is estimated 10 to 28% of all patients. The goal of this study is to evaluate the incidence of this complication in our experience, preoperative risk factors, therapeutic implications and short outcome. 132 consecutive patients underwent pneumonectomy for lung cancer. We retrospectively studied this series of which 29 patients developed arrhythmias postoperatively. Mean age was 58 years (48 to 79), 16 patients were older than 65 years. Seven patients had medical history of either myocardial infarction or hypertension. Arrhythmias appeared post-operatively on days 1 and 2 six times, days 3 ans 4 ten times, days 5 to 6 six times and days 7 to 10 twice. The trouble consisted in atrial fibrillation in 18 patients, atrial associated with ventricular premature beats in 11 patients. Antiarrhythmic medication (amiodarone) was started as soon as the trouble was confirmed by EKG in all cases. Normalization was obtained in 27 patients (95%). One patient remained dysrrhythmic in spite of treatment. One death occurred on day 4 postoperatively. The mean hospitalisation stay was 10 days.</AbstractText>Cardiac arrhythmia in the immediate postoperative course is not rare. Early diagnosis in patients at risk followed by adequat treatment is necessary to avoid haemodynamic storm in these quite fragile patients. Amiodarone is the treatment of choice.</AbstractText>
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3,352
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Relation of left ventricular hypertrophy to cardiovascular complications in diabetic hypertensives.
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The presence of diabetes mellitus and other risk factors of atherosclerosis, such as obesity, smoking and hyperlipidemia, in hypertensive patients makes the prognosis worse. Authors compared the clinical findings in diabetic hypertensive patients with and without left ventricular hypertrophy, the presence of which was diagnosed and defined by echocardiography. The study is based on the analysis of hospital records of 115 hypertensive patients treated at our department during the period 1998-1999. Left ventricular hypertrophy (LVH) was defined by echocardiography as left ventricular mass index > 134 g/m2 in men and > 110 g/m2 in women. Left ventricular hypertrophy was found in 79 patients (mean age 64.6 ys) but not in 36 patients (mean age 63.3 ys). Both groups were matched as to age and sex, intensity and duration of hypertension and diabetes, obesity, smoking and hyperlipidemia. In LVH-positive patients, there was a statistically significant incidence of heart failure, mitral regurgitation and renal involvement and a more non-significant incidence of left ventricular diastolic dysfunction, myocardial infarction, chronic atrial fibrillation and stroke than in LVH-negative ones. Left ventricular hypertrophy usually complicates the course of hypertension. Authors recommend to investigate the presence of left ventricular hypertrophy in hypertensives as it carries a much more complicated course of the disease. (Tab. 5, Ref. 28.)
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3,353
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[A case of ventricular fibrillation during emergency clipping operation for cerebral aneurysm].
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A 59 year-old woman with subarachnoid hemorrhage underwent emergency neck clipping of cerebral aneurysm. Her preoperative examination showed atrial fibrillation, pulmonary edema and hypokalemia. Ventricular fibrillation developed immediately after clipping of the aneurysm and recurred 7 times thereafter during the surgery. Hypokalemia was corrected, and hypoxemia and other factors leading to ventricular fibrillation were excluded. RR interval was prolonged prior to ventricular fibrillation. Therefore intravenous temporary cardiac pacemaker was inserted immediately after the end of the surgery. It prevented successfully the prolongation of RR interval as well as ventricular fibrillation. The present case suggests that we should pay attention to the possibility of ventricular fibrillation during emergency radical surgery for ruptured cerebral aneurysm, and that cardiac pacemaker is useful to prevent ventricular fibrillation following prolongation of RR interval.
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3,354
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Activity-rest stimulation protocol improves cardiac assistance in dynamic cardiomyoplasty.
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No data have ever been published regarding cardiac assistance in demand dynamic cardiomyoplasty (DDCMP). We tested the efficacy of the Doppler flow wire in measuring beat-to-beat aortic flow velocity and evaluating cardiac assistance in demand cardiomyoplasty patients.</AbstractText>The technique was tested in seven patients (M/F=6/1; age=57.1+/-6.2 years; atrial fibrillation/sinus rhythm=1/6; NYHA=1.4+/-0.5). Measurements were done using a 0.018inch peripheral Doppler flow wire advanced through a 5F arterial femoral sheath. Three 1-min periods with the stimulator off and three 1-min periods with clinical stimulation were recorded. We measured peak aortic flow velocity in all beats. Latissimus dorsi (LD) mechanogram was simultaneously recorded.</AbstractText>Comparison between pre-operative and follow-up data showed significantly higher values of tetanic fusion frequency (TFF) and ejection fraction at follow-up, whereas mean NYHA class was significantly lower. Statistical analysis showed an increase in aortic flow velocity not only in assisted versus rest period, but also in assisted versus unassisted beats (8.42+/-6.98% and 7.55+/-3.07%). A linear correlation was found between the increase in flow velocity and LD wrap TFF (r(2)=0.53).</AbstractText>In DDCMP, systolic assistance is significant and correlated to LD speed of contraction; demand stimulation protocol maintains muscle properties and increases muscle performance.</AbstractText>
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3,355
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Asymptomatic versus symptomatic persistent atrial fibrillation: clinical and noninvasive characteristics.
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This prospective study was designed to investigate the differences between asymptomatic versus symptomatic arrhythmia as well as left ventricular dysfunction in a consecutive population of patients with persistent atrial fibrillation.</AbstractText>A total of 282 consecutive outpatients referred with persistent atrial fibrillation formed the study population. A structured medical history was obtained. A two-dimensional transthoracic echocardiography to assess the left ventricular function and a 24-h electrocardiogram (ECG) recording were performed. Irregularity of the heart rhythm was analysed with heart rate variability (HRV) in the time domain as well as maximum and minimum heart rate and the longest pause.</AbstractText>Three university hospitals.</AbstractText>The mean age of the patients was 69 years and the mean duration of atrial fibrillation was 7 months. The prevalence of symptomatic patients was 68%, while 32% had no symptoms from atrial fibrillation, left ventricular dysfunction was observed in 20%. Asymptomatic subjects had more often lone atrial fibrillation than those with symptoms. Valvular heart disease was an independent predictor of symptoms while male gender, ischaemic heart disease and a high heart rate were independent predictors of impaired left ventricular function.</AbstractText>Valvular heart disease is related to symptoms in persistent atrial fibrillation. Ischaemic heart disease, male gender and a high heart rate are more common in patients with impaired left ventricular function. Compromised left ventricular function does, occur also in asymptomatic subjects underlining the importance of a careful investigation including echocardiography in all subjects with persistent atrial fibrillation.</AbstractText>
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3,356
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Clinical meaning of ascites in patients with endomyocardial fibrosis.
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To evaluate the clinical meaning of ascites and the main features of patients with ascites and endomyocardial fibrosis.</AbstractText>We studied 166 patients with endomyocardial fibrosis (mean age 37 years, 114 women) treated over the last 20 years. Ventriculography findings, surgery or necropsy confirmed the diagnosis in all patients. Most patients belonged to New York Heart Association Functional Class III/IV (134, 83.7%). Eighty-one (50.6%) had biventricular, 28 (17.5%) had right ventricular, and 51 (31.8%) had left ventricular involvement. During follow-up, 56 patients died.</AbstractText>Ascites was present in 67 (41.8%) patients, and right ventricular involvement was present in 59 (88%). In the comparison between patients with or without ascites, those with ascites had higher mortality (49.2% and 24.7%, respectively). Patients with ascites had a higher incidence of edema (95% vs. 43%), hepatomegaly (5.8cm vs. 4.1cm), mean right atrium pressure (19.3 vs. 12mmHg), and final right ventricle diastolic pressure (18.7 vs. 12.9mmHg). Also, patients with ascites had a longer history of illness (5.1 and 3.9 years, respectively) and had atrial fibrillation more frequently (44.7% vs. 30.1%).</AbstractText>Ascites was observed in less than 50% of cases of endomyocardial fibrosis and was associated with greater involvement of the right ventricle and with a longer duration of the disease, thus being a characteristic of a worse prognosis.</AbstractText>
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3,357
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Cold water submersion and cardiac arrest in treatment of severe hypothermia with cardiopulmonary bypass.
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In the paediatric population, submersion injury with drowning or near-drowning represents a significant cause of morbidity and mortality. This study reviews retrospectively our own experiences and the literature on the use of cardiopulmonary bypass (CPB) to rewarm paediatric victims of cold water submersion who suffer severe hypothermia (<28 degrees C) and cardiac arrest (asystole or ventricular fibrillation). In addition to three children treated at our institution, nine other victims were found in the literature. In this cohort of 12 children aged between 2 and 12 years, there was a tendency to better outcome with lower core temperature at the beginning of extracorporeal circulation (mean temperature in nine survivors, 20 degrees C; in three non-survivors, 25.5 degrees C). The lowest temperature survived was 16 degrees C. Neither base excess, pH nor serum potassium levels were reliable prognostic factors. The lowest base excess in a survivor was -36.5 mmol/l, the lowest pH 6.29. We consider CPB as the method of choice for resuscitation and rewarming of children with severe accidental hypothermia and cardiac arrest (asystole or ventricular fibrillation). Compared with adults, children, especially smaller ones, require special consideration with regard to intravenous cannulation as drainage can be inadequate using femoral-femoral cannulation. In hypothermic children we advocate, therefore, emergency median sternotomy. Until more information regarding prognostic factors are available, children who are severely hypothermic and clinically dead after submersion in cold water--even if for an unknown length of time--should receive cardiopulmonary resuscitation (CPR) and be transported without delay to a facility with capabilities for CPB instituted via a median sternotomy.
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3,358
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The epidemiology of out-of-hospital 'sudden' cardiac arrest.
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It is difficult to assemble data from an out-of-hospital cardiac arrest since there is often lack of objective information. The true incidence of sudden cardiac death out-of-hospital is not known since far from all of these patients are attended by emergency medical services. The incidence of out-of-hospital cardiac arrest increases with age and is more common among men. Among patients who die, the probability of having a fatal event outside hospital decreases with age; i. e. younger patients tend to more often die unexpectedly and outside hospital. Among the different initial arrhythmias, ventricular fibrillation is the most common among patients with cardiac aetiology. The true distribution of initial arrhythmias is not known since several minutes most often elapse between collapse and rhythm assessment. Most patients with out-of-hospital cardiac arrest have a cardiac aetiology. Out-of-hospital cardiac arrests most frequently occur in the patient's home, but the prognosis is shown to be better when they occur in a public place. Witnessed arrest, ventricular fibrillation as initial arrhythmia and cardiopulmonary resuscitation are important predictors for immediate survival. In the long-term perspective, cardiac arrest in connection with acute myocardial infarction, high left ventricular ejection fraction, moderate age, absence of other heart failure signs and no history of myocardial infarction promotes better prognosis. Still there is much to learn about time trends, the influence of patient characteristics, comorbidity and hospital treatment among patients with prehospital cardiac arrest.
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3,359
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Hypertrophic cardiomyopathy: a systematic review.
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Throughout the past 40 years, a vast and sometimes contradictory literature has accumulated regarding hypertrophic cardiomyopathy (HCM), a genetic cardiac disease caused by a variety of mutations in genes encoding sarcomeric proteins and characterized by a broad and expanding clinical spectrum.</AbstractText>To clarify and summarize the relevant clinical issues and to profile rapidly evolving concepts regarding HCM.</AbstractText>Systematic analysis of the relevant HCM literature, accessed through MEDLINE (1966-2000), bibliographies, and interactions with investigators.</AbstractText>Diverse information was assimilated into a rigorous and objective contemporary description of HCM, affording greatest weight to prospective, controlled, and evidence-based studies.</AbstractText>Hypertrophic cardiomyopathy is a relatively common genetic cardiac disease (1:500 in the general population) that is heterogeneous with respect to disease-causing mutations, presentation, prognosis, and treatment strategies. Visibility attached to HCM relates largely to its recognition as the most common cause of sudden death in the young (including competitive athletes). Clinical diagnosis is by 2-dimensional echocardiographic identification of otherwise unexplained left ventricular wall thickening in the presence of a nondilated cavity. Overall, HCM confers an annual mortality rate of about 1% and in most patients is compatible with little or no disability and normal life expectancy. Subsets with higher mortality or morbidity are linked to the complications of sudden death, progressive heart failure, and atrial fibrillation with embolic stroke. Treatment strategies depend on appropriate patient selection, including drug treatment for exertional dyspnea (beta-blockers, verapamil, disopyramide) and the septal myotomy-myectomy operation, which is the standard of care for severe refractory symptoms associated with marked outflow obstruction; alcohol septal ablation and pacing are alternatives to surgery for selected patients. High-risk patients may be treated effectively for sudden death prevention with the implantable cardioverter-defibrillator.</AbstractText>Substantial understanding has evolved regarding the epidemiology and clinical course of HCM, as well as novel treatment strategies that may alter its natural history. An appreciation that HCM, although an important cause of death and disability at all ages, does not invariably convey ominous prognosis and is compatible with normal longevity should dictate a large measure of reassurance for many patients.</AbstractText>
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3,360
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Protective effects of poly (ADP-ribose) synthase inhibitors on digoxin-induced cardiotoxicity in guinea-pig isolated hearts.
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Reactive oxygen species, generated and released during digoxin-induced cardiotoxicity, can produce an activation of poly (ADP-ribose) synthase (PARS). Our objective was to examine the effects of PARS inhibitors, 3-aminobenzamide (3-AB ) and nicotinamide, on digoxin-induced arrhythmias in guinea-pig isolated hearts. 3-AB (0.1-0.3 mM) and nicotinamide (0.3 mM) were added to the perfusion solution starting 10 min before digoxin infusion (8 microg x ml (-1)min (-1)reaching the heart) and maintained throughout the experiments. Electrocardiograms and coronary perfusion pressure were recorded continuously, and digoxin-induced arrhythmias were determined. Nicotinamide markedly inhibited ventricular tachycardia (VT) incidence (from 100%, n= 7, to 29%, n= 7), and abolished ventricular fibrillation (VF) incidence. 3-AB (0.1 mM, n= 9) significantly decreased VT incidence from 100% ( n= 7) to 22% ( n= 9) and VF incidence from 86% ( n= 7) to 11% ( n= 9). Both nicotinamide and 3-AB (0.1 mM) markedly decreased number of ventricular ectopic beats (VEBs) and arrhythmia score. 3-AB at 0.3 mM ( n= 8) appeared to decrease the VT (to 63%) and VF incidence (to 38%), but these reductions did not reach statistically significance levels. Moreover, 3-AB at high concentration (0.3 mM) did not significantly modify the number of VEBs and arrhythmia score. There were no significant changes in coronary perfusion pressure, heart rate or pressure rate index measured at certain time points throughout the experiment in all groups. Our results suggest that PARS activation plays a role in the digitalis-induced cardiotoxicity in guinea-pig isolated hearts.
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3,361
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Role of Purkinje conducting system in triggering of idiopathic ventricular fibrillation.
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Ventricular fibrillation is the main mechanism of sudden cardiac death, but the source of its spontaneous initiation has not been mapped. 16 patients were investigated by electrography and radiofrequency ablation after resuscitation from recurrent idiopathic ventricular fibrillation. Triggers of ventricular fibrillation originated from various locations within the Purkinje system in 12 patients and from the ordinary myocardial muscle in four. The accuracy of mapping was confirmed by acute elimination of triggers by radiofrequency delivery, and there was no recurrence of ventricular fibrillation in 14 patients. Long-term follow-up is necessary to establish that ablation is curative and avoids use of a defibrillator.
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3,362
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Clinical profile and spectrum of commotio cordis.
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Although blunt, nonpenetrating chest blows causing sudden cardiac death (commotio cordis) are often associated with competitive sports, dangers implicit in such blows can extend into many other life activities.</AbstractText>To describe the comprehensive spectrum of commotio cordis events.</AbstractText>Analysis of confirmed cases from the general community assembled in the US Commotio Cordis Registry occurring up to September 1, 2001.</AbstractText>Commotio cordis event.</AbstractText>Of 128 confirmed cases, 122 (95%) were in males and the mean (SD) age was 13.6 (8.2) years (median, 14 years; range, 3 months to 45 years); only 28 (22%) cases were aged 18 years or older. Commotio cordis events occurred most commonly during organized sporting events (79 [62%]), such as baseball, but 49 (38%) occurred as part of daily routine and recreational activities. Fatal blows were inflicted with a wide range of velocities but often occurred inadvertently and under circumstances not usually associated with risk for sudden death in informal settings near the home or playground. Twenty-two (28%) participants were wearing commercially available chest barriers, including 7 in whom the projectile made direct contact with protective padding (baseball catchers and lacrosse/hockey goalies), and 2 in whom the projectile was a baseball specifically designed to reduce risk. Only 21 (16%) individuals survived their event, with particularly prompt cardiopulmonary resuscitation/defibrillation (most commonly reversing ventricular fibrillation) the only identifiable factor associated with a favorable outcome.</AbstractText>The expanded spectrum of commotio cordis illustrates the potential dangers implicit in striking the chest, regardless of the intent or force of the blow. These findings also suggest that the safety of young athletes will be enhanced by developing more effective preventive strategies (such as chest wall barriers) to achieve protection from ventricular fibrillation following precordial blows.</AbstractText>
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3,363
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Successful defibrillation in the prone position.
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Early defibrillation provides the greatest chance of survival after ventricular fibrillation. Conventional cardiopulmonary resuscitation and defibrillation requires the patient to be in the supine position. Electrical treatment of arrhythmias such as atrial fibrillation by means of a defibrillator back paddle in patients receiving prone ventilation in intensive care has been described. We report a case in which electrical defibrillation was successfully performed in the prone position in a patient undergoing complex spinal surgery. We suggest that, if defibrillation were required in ventilated patients positioned prone, defibrillation should be attempted in the prone position, as turning the patient supine would consume valuable minutes and reduce the chances of successful defibrillation.
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3,364
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[Effect of long-term treatment with enalapril, losartan and their combination on the quality of life of patients with congestive heart failure].
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To study the effect a combination of enalapril and losartan on life quality in patients with congestive heart failure (HF).</AbstractText>One hundred and eighty six patients with NYHA functional classes II to IV HF were examined. The study inclusion criteria were as follows: a left ventricular (LV) end-diastolic volume of > 160 ml, a LV ejection fraction of < 35%, sinus rhythm, a cardiothoracic index of > 0.55, no history data on prior treatment with an angiotensin-converting enzyme inhibitor (ACEI) and/or an AT1-antagonist, a patient's written free-will consent to participate in the study. The exclusion criteria were as follows: pacemaker migration, an artificial pacemaker, high-degree block, atrial fibrillation, cerebral circulatory disorders. All the patients were divided into 4 groups and received basic therapy with cardicet, 60-120 mg/day, aspirin, 250 mg/day, furosemide, 80-440 mg/week, and digoxin, 0.25-0.5 mg/day. Group 1 comprised 60 patients who refused therapy with ACEI and/or AT1-antagonist despite that they had indications for their use and they had been convinced many times. In Group 2 (n = 82) enalapril, an ACEI, was added to the basic therapy. Its initial dose of 2.5 mg/day was given once and slowly incremented to the therapeutical one (10-20 mg/day). Group 3 patients (n = 56) on the basic therapy were additionally treated with the AT1-antagonist losartan in a daily dose of 25-50 mg. They were started on 12.5 mg a day. In group 4 the basic therapy was added by a combination of enalapril and losartan in the same doses. The follow-up was 48 weeks. The efficiency of the treatments was controlled by the personal questionnaires SF-36, Life with Heart Failure, by evaluating the magnitude of clinical HF manifestations and by estimating the total life quality inxed. The data were analyzed by assuming that all the patients received the treatments.</AbstractText>As compared with the conventional therapy and the use of each drug alone, a combination of the ACEI enalapril and the AT1-antagonist losartan promotes a more significant increase in the satisfaction of the patients with their vital activity, in the critical rate of their self-assessment of the "internal picture" of disease, and leads to a greater improvement of the quality of their life as a whole.</AbstractText>The ICAE-AT1-antagonist combination exerts a positive impact on life quality in patients with heart failure.</AbstractText>
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3,365
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Effect of electrode location in great cardiac vein on the ventricular defibrillation threshold.
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This study tested the hypothesis that the DFT could be lowered by delivering a weak auxiliary shock in conjunction with a stronger primary shock with the auxiliary shock electrode near the cardiac region where the primary shock electric field is weakest. This hypothesis was tested by determining the DFTs with the auxiliary shock delivered from different locations within the great cardiac vein (GCV). In 15 dogs, catheters with defibrillation electrodes were placed transvenously in the RV apex, the SVC, and the GCV. An active can electrode and the SVC electrodes were electrically coupled to serve as a return electrode for the RV and GCV electrodes. DFTs were determined for a primary shock through the RV electrode with and without a subsequent auxiliary shock of lower amplitude through the GCV electrode. The leading edge voltage and current at DFT were significantly lowered by addition of the auxiliary shock (17% and 19% decreased, respectively), but energy was not changed. The animals were divided into three groups according to the location of the GCV electrode. The leading edge voltage, current, and total delivered energy at the DFT were significantly lower in animals with the GCV electrode near the apex (22%, 24%, and 13% reduction, respectively) compared with those where the GCV electrode was positioned away from apex (8%, 10% reduction and 18% increase, respectively, P < 0.001). Application of an auxiliary shock to the apical region, near the region where previous studies have indicated that the RV primary shock has its weakest effects, caused the greatest decrease in DFT.
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3,366
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QT dispersion in 120 electrocardiographic leads in patients with structural heart disease.
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The clinical significance of QT dispersion (QTd) measured in 12-lead ECGs is controversial. The aim of this study was to clarify factors that determine the QTd and its measurement errors in different lead arrays in patients with structural heart disease. Two blinded observers measured QT intervals on a computer screen from 120-channel ECG recordings in a retrospective set of 257 patients, comprising a group of 121 myocardial infarction (MI) survivors without ventricular tachyarrhythmia during a 6-month follow-up and a group of 136 survivors of ventricular tachyarrhythmia/fibrillation. QTd did not differ in patients with and without ventricular tachyarrhythmia/fibrillation. Eleven ventricular tachyarrhythmia/fibrillation survivors without structural heart disease had the lowest QTd (P < or = 0.02). The strongest factor determining QTd and the magnitude of its measurement error was the lead array (P = 0.0001). Measurement errors had two components. The smallest relative errors were in the total body surface mapping array with one component related to interobserver reproducibility (9.1 +/- 7.6%), and the other component related to accuracy of measurement of the QT interval (36 +/- 16%). The authors estimated that a difference of QTd of at least 50 ms between study groups is required in a 12-lead ECG to draw any conclusions from the studies. In patients with structural heart disease, QTd from limited arrays of ECG leads was not a reliable measure. It correlated with the presence of structural heart disease, but not with arrhythmogenicity. An array consisting of ECG leads covering the entire chest allowed better reproducibility and measurement accuracy of QTd.
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3,367
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Effect of ventricular fibrillation duration on the defibrillation threshold in humans.
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Early during ventricular fibrillation, the defibrillation threshold may be low, as ventricular fibrillation most probably arises from a localized area with only a few wavefronts and the effects of global ischemia, ventricular dilatation, and sympathetic discharge have not yet fully developed. The purpose of this study was to explore the effect of the timing of shock delivery in humans. During implantation of an ICD in 26 patients (24 men, 60 +/- 11 years, 19 coronary artery disease, NYHA 2.2 +/- 0.4, left ventricular ejection fraction 0.42 +/- 0.16), the defibrillation threshold was determined after approximately 10 and 2 seconds of ventricular fibrillation. Ventricular fibrillation was induced by T wave shocks. Mean defibrillation threshold was 9.9 +/- 3.6 J after 10.3 +/- 1.0 seconds. Within 2 seconds, 20 of 26 patients could be successfully defibrillated with < or = 8 J. In these patients, the mean defibrillation threshold was 4.0 +/- 2.1 J after 1.4 +/- 0.3 seconds compared to 9.5 +/- 3.1 J after 10.2 +/- 1.1 seconds (P < 0.001). There were no clinical differences between patients who could be successfully defibrillated within 2 seconds and those patients without successful defibrillation within 2 seconds. In the majority of patients, the defibrillation threshold was significantly lower within the first few cycles of ventricular fibrillation than after 10 seconds of ventricular fibrillation. These results should lead to exploration of earlier shock delivery in implantable devices. This could possibly reduce the incidence of syncope in patients with rapid ventricular tachyarrhythmias and ICDs.
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3,368
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Non-surgical myocardial reduction in hypertrophic obstructive cardiomyopathy.
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Percutaneous transluminal septal ablation was recently introduced as an alternative to surgical treatment of hypertrophic obstructive cardiomyopathy. In this procedure, alcohol is injected into a proximal septal artery to create a localized myocardial infarction.</AbstractText>To characterize the immediate and medium-term results following PTSMA.</AbstractText>Of 13 patients referred for PTSMA, 8 were found suitable for the procedure. Hemodynamic parameters were evaluated prior to and following the procedure, and clinical and echo-Doppler parameters at 2 weeks and 9 months later.</AbstractText>The procedure was technically successful in all patients. Resting left ventricular outflow gradient at rest (by Doppler) fell from 82 +/- 37 to 15 +/- 8 mmHg (P < 0.001) 9 months later. Late post-procedural gradient after the Valsalva maneuver was 2 +/- 24 mmHg. The degree of mitral regurgitation fell from 2.0 +/- 0 to 1.5 +/- 0.5 (P < 0.05). New York Heart Association class for dyspnea improved from 2.8 +/- 0.5 to 1.8 +/- 0.8 (P < 0.01) and Canadian Cardiovascular Society class for angina from 2.0 +/- 1.3 to 1.3 +/- 1.2 (P = 0.08). Complete right bundle branch block developed in six patients, temporary complete atrioventricular block in three, and persistent block requiring permanent pacing in one. No flow in the distal left anterior descending coronary artery (presumably due to spilling of alcohol) was seen in one (with development of a small antero-apical infarction) and ventricular fibrillation 2 hours post-procedure in one. None of the patients died.</AbstractText>PTSMA provided a substantial reduction in left ventricular outflow gradient associated with an improvement in symptomatology. Serious complications are not uncommon. Long-term follow-up is unknown.</AbstractText>
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3,369
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Rate control versus electrical cardioversion for atrial fibrillation: A randomised comparison of two treatment strategies concerning morbidity, mortality, quality of life and cost-benefit - the RACE study design.
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Persistent atrial fibrillation (AF) does not terminate spontaneously and may cause left ventricular dysfunction and thromboembolic complications. For restoration of sinus rhythm electrical cardioversion (ECV) is most effective. However, AF frequently relapses, necessitating re-ECV and institution of potentially harmful antiarrhythmic drugs. If AF is accepted, rate control and prevention of thromboembolic complications using negative chronotropic drugs and warfarin is pursued. It is our hypothesis that rate control therapy is not inferior to ECV therapy in preventing morbidity and mortality.</AbstractText>RACE (RAte Control versus Electrical cardioversion for atrial fibrillation) is a randomised comparison of serial ECV therapy (repeat ECV as soon as possible after a relapse and institution of an antiarrhythmic drug: sotalol, class IC drug and amiodarone) and rate control therapy (resting heart rate <100 bpm using digitalis, calcium channel blockers and/or β-blockers) in patients with persistent AF. Morbidity (heart failure, side effects of drugs, thromboembolic complications, bleeding and pacemaker implantation), mortality, quality of life and cost-effectiveness are primary and secondary endpoints. Included are patients with a recurrence of persistent AF, present episode <1 year and a maximum of two previous successful ECVs during the last two years. This study is a multicentre study in 31 centres throughout the Netherlands. All 520 patients have now been included. Follow-up is two years. The results are expected this year.</AbstractText>
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3,370
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[Alternative pacing sites for the prevention of atrial fibrillation].
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Background The induction of atrial fibrillation depends upon the interaction between basic rhythm, ectopic activity, and inter-/intraatrial conduction. In pacing therapy, the atrial pacing site may influence the incidence of atrial tachyarrhythmias. This review discusses the antiarrhythmic potential of different atrial pacing sites. Results Three atrial pacing modes have been evaluated with respect to their potential to prevent atrial tachyarrhythmias: biatrial, bifocal right atrial, and dedicated unifocal right atrial pacing sites. Biatrial pacing aims at shortening the global atrial activation time in patients with interatrial conduction block. Observational studies showed a suppression of atrial tachyarrhythmias in 1/3 of patients, while a randomized study could not demonstrate a significant effect. Bifocal pacing at the high right atrium and coronary sinus os showed a higher preventive efficacy than unifocal pacing in a single center experience which was partly confirmed by a multicenter trial. Atrial septal pacing at the triangle of Koch provides antiarrhythmic effects but may be more difficult to reach and limited by oversensing of ventricular far-field signals. A randomized study found a preventive effect of pacing near Bachmann's bundle; this site seems particularly attractive for its easy access and low risk of ventricular far-field oversensing. Conclusions In patients with an indication for permanent pacing and paroxysmal or persistent atrial fibrillation, the atrial pacing site may facilitate maintenance of sinus rhythm. While reliable sensing and pacing are prerequisites, particularly high septal atrial pacing may provide an additional antiarrhythmic effect at an expenditure comparable to conventional atrial pacing sites.
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3,371
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Implantable defibrillator event rates in patients with idiopathic dilated cardiomyopathy, nonsustained ventricular tachycardia on Holter and a left ventricular ejection fraction below 30%.
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This study investigated the incidence of appropriate implantable cardioverter defibrillator (ICD) interventions for ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients with idiopathic dilated cardiomyopathy (IDC) and nonsustained VT in the presence of a left ventricular ejection fraction below 30%, versus in patients with syncope and patients with a history of VT or VF.</AbstractText>To date, only limited information is available about the prophylactic use of ICDs in patients with IDC.</AbstractText>From January 1993 to July 2000, 101 patients with IDC underwent implantation of ICDs with electrogram storage capability at our institution. Patients were placed into one of three groups according to their clinical presentation: asymptomatic or mildly symptomatic nonsustained VT in the presence of a left ventricular ejection fraction < or = 30% (49 patients, prophylactic group), unexplained syncope or near syncope (26 patients, syncope group) and a history of sustained VT or VF (26 patients, VT/VF group).</AbstractText>During 36 +/- 22 months follow-up, 18 of 49 patients (37%) in the prophylactic group received appropriate shocks for VT or VF, compared with 8 of 26 patients (31%) in the syncope group and with 9 of 26 patients (35%) of the VT/VF group. Multivariate Cox analysis of baseline clinical variables identified left ventricular ejection fraction, atrial fibrillation and a history of sustained VT or VF as predictors for appropriate ICD interventions during follow-up.</AbstractText>Patients with IDC and prophylactic ICD implantation for nonsustained VT in the presence of a left ventricular ejection fraction < or = 30% had an incidence of appropriate ICD interventions similar to that of patients with a history of syncope or sustained VT or VF. These findings indicate that ICDs may have a role in not only secondary but also primary prevention of sudden death in IDC.</AbstractText>
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3,372
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Effect of shock polarity on the efficacy of transthoracic atrial defibrillation.
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The energy requirement for internal ventricular defibrillation is reduced by reversal of shock polarity. The influence of shock polarity on the efficacy of transthoracic atrial defibrillation is unknown.</AbstractText>This prospective, randomized study enrolled 110 consecutive patients who were referred for elective cardioversion of persistent atrial fibrillation (AF). The electrodes were placed in the anteroposterior position. The patients were randomized to receive either standard (anterior pad = cathode) or reversed polarity (anterior pad = anode) shocks with a damped sinusoidal monophasic waveform. A step-up protocol was used to estimate the cardioversion threshold. The initial shock energy was 50 J, with subsequent increments to 100, 200, 300, and 360 J in the event of cardioversion failure.</AbstractText>Sixty-four percent of the patient population were men, with a mean age of 66 +/- 13 years and a mean duration of AF of 242 +/- 556 days. The overall success rates of cardioversion were 84% for standard polarity and 78% for reversed polarity (P not significant). Among the patients who were successfully cardioverted, the mean atrial defibrillation threshold was 198 +/- 103 J for standard polarity and 212 +/- 107 J for reversed polarity (P not significant).</AbstractText>Reversal of shock polarity does not improve transthoracic cardioversion efficacy with a standard damped sinusoidal monophasic waveform. Alternate strategies should be considered for patients who fail external cardioversion, such as adjunctive pharmacologic treatment, use of a biphasic shock waveform, or internal cardioversion.</AbstractText>
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3,373
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Syncopal episodes in a young amateur body builder.
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A 36 year old male weight training enthusiast suffered several syncopal episodes. An electrocardiogram confirmed atrial fibrillation with normal ventricular response. The patient admitted to taking anabolic steroids and bromocriptine. The atrial fibrillation was considered to be due to bromocriptine misuse.
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3,374
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Atrial fibrillation: strategies to control, combat, and cure.
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Atrial fibrillation is the commonest clinical arrhythmia, is increasing in incidence and prevalence, and is associated with substantial morbidity and mortality. The arrhythmia may be paroxysmal (self-limiting), persistent (amenable to cardioversion), or permanent. Especially in its paroxysmal form, atrial fibrillation may be initiated by rapidly firing foci, generally located in the proximal pulmonary veins. Sustained atrial fibrillation is maintained by an atrial tissue substrate capable of accommodating many meandering wavelets. With continuing arrhythmia, the electrophysiological properties of the atria change and further facilitate continuing fibrillation. Treatment is aimed at prevention of thromboembolic complications, restoration and maintenance of sinus rhythm, and control of ventricular rate during atrial fibrillation. With greater understanding of the arrhythmia mechanisms, it is becoming possible to offer targeted curative treatments to more and more patients.
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3,375
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Long-term follow-up of patients after coarctation of the aorta repair.
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Late cardiovascular complications after operative repair of coarctation of the aorta include systemic hypertension, premature coronary artery disease, aortic valve abnormalities, aortic aneurysm, and recoarctation. We report the outcome in 274 subjects greater-than-or-equal50 years after coarctation repair. Operative repair of simple coarctation was performed on 274 patients at the University of Minnesota Hospital between 1948 and 1976. Twenty patients (7%) died in the immediate postoperative period. Of the 254 survivors, 2 were lost to follow-up, 45 (18%) died at a mean age of 34 years, and 207 (81%) were alive greater-than-or-equal50 years after the original operation. Coronary artery disease and perioperative deaths at the time of a second cardiac operation accounted for 17 of the 45 late deaths. Predictors of survival were age at operation and blood pressure at the first postoperative visit. Of the 207 long-term survivors, 92 (48%) participated in a clinical cardiovascular evaluation. Thirty-two of the 92 subjects had systemic hypertension that was predicted by age at operation, blood pressure at the first postoperative visit, and paradoxic hypertension at operative repair. New cardiovascular abnormalities detected at follow-up evaluation included evidence of a previous myocardial infarction, cardiomyopathy, atrial fibrillation, moderate to severe left ventricular outflow tract obstruction, moderate aortic valve regurgitation, recoarctation, and ascending aortic dilation. Thus, long-term survival is significantly affected by age at operation, with the lowest mortality rates observed in patients who underwent surgery between 1 and 5 years of age. More than 1/3 of the survivors developed significant late cardiovascular abnormalities.
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3,376
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Biventricular pacing--early experience.
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Biventricular pacing has been studied for the treatment of chronic heart failure (CHF). This technique seems to be able to improve symptoms and exercise tolerance, in patients with advanced CHF and prolonged QRS duration.</AbstractText>To present our experience with biventricular pacing in the management of severe CHF.</AbstractText>Between June 2000 and March 2001, 8 patients with dilated cardiomyopathy and left bundle branch block (LBBB) were selected for transvenous biventricular pacing system implantation. Mean age: 54.12 +/- 16.8 years; 5 males. The etiology was: idiopathic in 6 cases; operated congenital heart disease in 1, and ischemic in the other. Despite tailored treatment of CHF (with all patients taking diuretics and angiotensin-converting enzyme inhibitors), 7 patients remained in NYHA class III and 1 in IV. The quality of life score (assessed by the "Minnesota living with heart failure questionnaire") was 62.25 +/- 11.29. Seven patients had sinus rhythm and only one chronic atrial fibrillation; mean PQ duration--220 +/- 76.37 ms; mean QRS duration--168.75 +/- 20.31 ms.</AbstractText>Implant failure, due to coronary sinus dissection and to excessive fluoroscopy time, with no coronary sinus catheterization, occurred in 2 cases (success rate: 75%). Implant data: mean implant procedure duration: 122.5 +/- 47.82 min; mean fluoroscopy time: 35.66 +/- 22.06 min; QRS duration, after implant: 133.33 +/- 15.05 ms. Left ventricular lead final position: anterolateral in 2 patients and lateral in 4. Pacing thresholds: biventricular--1.36 +/- 0.6 V; right ventricle--0.28 +/- 0.04 V; right atrium--0.32 +/- 0.08 V. Pacing impedance (left ventricle): 1013.33 +/- 147.87 omega. Follow-up (1st and 3rd month): one patient died, suddenly, 15 days after the procedure. In the others, an improvement in the quality of life index and functional class was found. These results were independent of echocardiography data. There were no significant differences in the pacing threshold and impedance during the follow-up.</AbstractText>Patients with advanced CHF and widened QRS benefited from biventricular stimulation, in which improvement on the clinical status was evident.</AbstractText>
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3,377
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Prognosis in patients with heart failure and preserved left ventricular systolic function.
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It is recognized that heart failure patients with preserved left ventricular systolic function have better prognosis; nevertheless, there are some studies with conflicting results. Also, there is a paucity of data concerning the prognostic factors in this group of patients.</AbstractText>To determine possible variables with prognostic relevance in heart failure patients with preserved left ventricular systolic function (ejection fraction > 40%).</AbstractText>157 consecutive ambulatory patients with heart failure were assessed; those patients with ejection fraction > 40% were included in the study (n = 46). All patients were evaluated by clinical interview and physical examination, ECG, echocardiogram (M-mode, 2D and pulsed Doppler of mitral flow), biochemical study and determination of type B natriuretic peptide (BNP). The patients were grouped according to the rhythm presented on ECG: Group I--patients with atrial fibrillation; Group II--patients in sinus rhythm Group II was further subdivided in two groups according to the presence or absence of restrictive left ventricular filling pattern. All patients had a clinical follow-up, with recording of events (death or hospitalization from cardiac cause). The mean follow-up time was 682.2 +/- 55 days.</AbstractText>The mean age of the patients was 70.4 +/- 1.2 years; 54.3% were women; mean ejection fraction was 49.6 +/- 1%; mean BNP levels were 202.9 +/- 41.3 pg/ml. Mortality was 19.6% and the combined event death or hospitalization from cardiac cause) occurred in 26.1% of the patients. Among the clinical, demographic, biochemical, echocardiographic and neurohumoral parameters, only BNP levels had prognostic significance in the whole population. In Group II patients, BNP levels, heart rate and restrictive left ventricular filling pattern were identified as having prognostic significance. Kaplan-Meyer curve analysis showed that both BNP and restrictive left ventricular filling pattern seemed to be important prognostic markers.</AbstractText>This preliminary study suggests thar neurohumoral activity (determined by plasma BNP levels) and a restrictive ventricular filling pattern may be important factors in prognostic stratification of heart failure patients with preserved left ventricular systolic function.</AbstractText>
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3,378
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Factors associated with early atrial fibrillation after ablation of common atrial flutter. A single centre prospective study.
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The occurrence of early atrial fibrillation (< or = 6 months) after ablation of common atrial flutter is of clinical significance. Variables predicting this evolution in ablated patients without a previous atrial fibrillation history have not been fully investigated.</AbstractText>The aim of the present study was: (1) to identify predictive factors of early atrial fibrillation (< or = 6 months) in the overall population following atrial flutter catheter ablation; (2) to identify predictive variables of early atrial fibrillation following (< or = 6 months) atrial flutter catheter ablation within a subgroup of patients without documented prior atrial fibrillation.</AbstractText>This study prospectively included 96 consecutive patients (age 65 +/- 13 years; 18 women) over a 12-month period. Their counterclockwise flutter was ablated by radiofrequency, by the same operator, with an 8-mm-tip catheter. Clinical, electrophysiological and echocardiographic data were collected and 27 variables were retained for analysis: age; gender; type of atrial flutter (permanent vs paroxysmal); symptom duration (months +/- SD); pre-ablation history of atrial fibrillation; structural heart disease; left ventricular ejection fraction (%); left atrial size (mm); cava--tricuspid isthmus dimension; septal isthmus dimension; systolic pulmonary pressure > or < or = 30 mmHg; right atrial area; left atrial area; isthmus block; number of radiofrequency applications (+/- SD); antiarrhythmic drugs at discharge; left ventricular diastolic diameter; left ventricular systolic diameter; left ventricular telediastolic volume; left ventricular telesystolic volume; A-wave velocity (cm . s(-1)); E-wave velocity (cm . s(-1)); E/A; isovolumetric relaxation time; E-wave deceleration time; significant mitral regurgitation and flutter cycle length (ms).</AbstractText>Of the 96 consecutive ablated patients, early atrial fibrillation was documented in 16 patients (17%). Atrial fibrillation occurred 30 +/- 46 days (range 1 to 171 days) after ablation. Univariate analysis associated an early occurrence of atrial fibrillation with: atrial fibrillation history, left ventricular ejection fraction, left atrial size, left ventricular telesystolic volume, A-wave velocity, significant mitral regurgitation and flutter cycle length. Multivariate analysis using a Cox model found that the only independent predictors of early atrial fibrillation were left ventricular ejection fraction and pre-ablation history of atrial fibrillation. In the subgroup without prior atrial fibrillation history (n=63; 66%), the only independent predictor of early atrial fibrillation was the presence of a significant mitral regurgitation.</AbstractText>In a subgroup of patients without atrial fibrillation history, 8% of patients revealed an early atrial fibrillation. Mitral regurgitation is a strong predictive factor of early atrial fibrillation occurrence with 80% sensitivity, 78% specificity and 98% negative predictive value. These data should be considered in post-ablation management.</AbstractText>Copyright 2001 The European Society of Cardiology.</CopyrightInformation>
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3,379
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Improved cardiac function and quality of life following upgrade to dual chamber pacing after long-term ventricular stimulation.
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Many patients with sinus node disease or atrioventricular block have previously received pacemakers with only ventricular stimulation (VVI or VVIR). This study aimed to investigate whether quality of life and cardiac function were affected by an upgrade to dual chamber pacing (DDDR or DDIR) following long-term ventricular stimulation.</AbstractText>After implantation of an atrial lead and a DDDR pulse generator, a randomized, double-blind crossover study was performed in 19 patients, previously treated with ventricular pacing for a median time of 6 X 8 years. Patients were randomized to 8 weeks with either VVIR or DDDR/DDIR pacing; after this time, the other mode was programmed for 8 weeks. At the end of each period, the patients' quality of life was evaluated and echocardiography was performed together with Holter monitoring and blood samples for brain natriuretic peptide.</AbstractText>Sixteen of the patients preferred DDDR and two VVIR pacing (P=0 X 001); one was undecided. Seven patients demanded an early crossover while paced in the VVIR mode, vs none in the DDDR mode (P=0 X 008). Quality of life was higher in the DDDR mode in 11 of 17 modalities, reaching statistical significance for dyspnoea (P<0 X 05) and general activity (P<0 X 05). Echocardiography showed significantly larger left ventricular end-diastolic dimensions in the DDDR mode (P=0 X 01), whereas end-systolic dimensions did not differ. Left ventricular systolic function was significantly superior in the DDDR mode (mean aortic velocity-time integral: P<0 X 001) and left atrial diameter was significantly smaller in the DDDR mode (P=0 X 01). The plasma level of brain natriuretic peptide was significantly lower in DDDR mode (P=0 X 002).</AbstractText>An upgrade to dual chamber rate adaptive pacing results in significantly improved quality of life and cardiac function as compared to continued VVIR stimulation and should thus be considered in patients with ventricular pacemakers who have not developed permanent atrial fibrillation or flutter.</AbstractText>Copyright 2001 The European Society of Cardiology.</CopyrightInformation>
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3,380
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Long-lasting sport practice and lone atrial fibrillation.
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To analyse whether the proportion of patients with lone atrial fibrillation engaged in chronic sport practice was higher than that observed in the general population.</AbstractText>The records of 1160 patients, seen at the arrhythmia outpatient clinic, were reviewed. A total of 70 patients (6%) suffered lone atrial fibrillation and were younger than 65 years. Thirty two of them had been engaged in long-term sport practice. All patients in the sport group were men as compared to only 50% in the sedentary group (P<0 x 0001). To avoid the confounding effect of sex distribution, women were excluded. Sportsmen started their episodes of atrial fibrillation at a younger age, they had a lower incidence of mild hypertension and their episodes of atrial fibrillation were predominantly vagal in contrast to the sedentary patients. The echocardiographic parameters were similar to those observed in the sedentary patients, but when compared with 20 healthy controls, they showed greater atrial and ventricular dimensions and a higher ventricular mass. The proportion of sportsmen among patients with lone atrial fibrillation is much higher than that reported in the general population of Catalonia: 63% vs 15% (P<0 x 05).</AbstractText>Long-term vigorous exercise may predispose to atrial fibrillation.</AbstractText>Copyright 2001 The European Society of Cardiology.</CopyrightInformation>
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3,381
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[Pharmacological and clinical profile of nifekalant (shinbit injection), a class III antiarrhythmic drug].
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Nifekalant (shinbit, MS-551) is a pure class III antiarrhythmic drug (Vaughan Williams' classification), which was approved in Japan in June 1999. This drug prolongs the action potential duration (APD) and the effective refractory period (ERP) in cardiac myocytes mainly by blocking the IKr (the rapid component of delayed rectifier K+ current). The antiarrhythmic efficacy depends on prolongation of ERP. The importance of this drug is to save patients from the life-threatening arrhythmias ventricular tachycardia (VT) and fibrillation (VF). Nifekalant was effective against reentrant arrhythmias such as VT and VF in postinfarction dogs. This drug does not have the negative inotropic effect that has been observed with other antiarrhythmic drugs. In clinical therapy, this drug was remarkably effective on patients who were unresponsive to therapy with other drugs or who were not able to receive other drugs due to decreased cardiac function. There has been no case of drug-induced worsening of the cardiac function. The significant adverse reaction is proarrhythmia such as ventricular tachycardia including TdP. Nifekalant is expected to be a useful drug for patients who could not be rescued from life-threatening arrhythmia by conventional therapies.
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3,382
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Limited antifibrillatory effectiveness of clinically relevant concentrations of class I antiarrhythmics in isolated perfused rat hearts.
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The Langendorff-perfused rat heart with regional ischemia is increasingly used for evaluating drugs for prevention of phase-1, ischemia-induced ventricular fibrillation (VF). Surprisingly, the effectiveness of Class I antiarrhythmics has not been characterized in this model. One lower and one higher concentration of quinidine (0.79 and 7.90 microM), lidocaine (3.88 and 12.93 microM), and flecainide (0.74 and 1.48 microM), representing the peak unbound plasma and total blood concentrations, respectively, at "therapeutic" dosage, were evaluated. The left main coronary artery was occluded for 30 min to elicit phase-1 VF, after which reperfusion-induced VF was examined. In hearts perfused with Krebs' solution containing 3 mM K(+), the higher concentrations of quinidine and lidocaine reduced the incidence of phase-1 VF from 92% to 0% and 17% respectively, (each p < 0.05). The lower drug concentrations were ineffective. Flecainide was equi-effective at low and high concentrations, with VF incidence reduced from 92% to 17% (p < 0.05). Neither low nor high concentrations of any of the drugs affected the incidence of reperfusion-induced VF. Using hearts perfused with Krebs' containing 5 mM K(+), sufficient to substantially reduce control phase-1 VF incidence, the experiment was repeated to test for possible proarrhythmic activity. None of the three drugs increased arrhythmia incidence. In this model, it was not possible to suppress ischemia-induced and reperfusion-induced VF with flecainide, lidocaine, or quinidine at concentrations equivalent to peak unbound plasma levels after clinical administration. This may explain the lack of clinical benefit with these drugs against sudden cardiac death. Because none of the drugs were proarrhythmic in ischemic hearts in which arrhythmia susceptibility had been lowered by high K(+), it would seem that clinical proarrhythmia seen with these drugs may not be related to exacerbation of phase-1, ischemia-induced VF.
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3,383
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Spatiotemporal transition to conduction block in canine ventricle.
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Interruption of periodic wave propagation by the nucleation and subsequent disintegration of spiral waves is thought to mediate the transition from normal sinus rhythm to ventricular fibrillation. This sequence of events may be precipitated by a period doubling bifurcation, manifest as a beat-to-beat alternation, or alternans, of cardiac action potential duration and conduction velocity. How alternans causes the local conduction block required for initiation of spiral wave reentry remains unclear, however. In the present study, a mechanism for conduction block was derived from experimental studies in linear strands of cardiac tissue and from computer simulations in ionic and coupled maps models of homogeneous one-dimensional fibers. In both the experiments and the computer models, rapid periodic pacing induced marked spatiotemporal heterogeneity of cellular electrical properties, culminating in paroxysmal conduction block. These behaviors resulted from a nonuniform distribution of action potential duration alternans, secondary to alternans of conduction velocity. This link between period doubling bifurcations of cellular electrical properties and conduction block may provide a generic mechanism for the onset of tachycardia and fibrillation.
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3,384
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New trends in the development of oral antidiabetic drugs.
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A large number of oral antidiabetic agents are available today. This article provides a short review of the pharmacology and some clinical aspects of various oral antidiabetic drugs. It focuses mainly on the newest developing drugs (therapy of the near future) and on the most commonly used older groups for the common approach of every-day practice (sulphonylureas). The primary goal of this review is to compare the electrophysiological effects of glibenclamide in isolated normal and streptozotocin induced diabetic rats and alloxan induced rabbits ventricular preparations, while on the other hand to differentiate the hypoglycaemic sulphonylureas (0.1-1000 mmol/kg) according to their cardiovascular activity in healthy and diabetic animals. In vitro (1-100 micromol/l) as well as chronically treated (5 mg/kg for 10 weeks) glibenclamide prolonged the action potential duration in normal but failed to affect it in diabetic ventricular preparations. Our results suggest that the sensitivity to glibenclamide of K(ATP) channels in diabetic ventricular fibers is drastically decreased. The effects of different sulphonylureas (tolbutamide, glibenclamide, gliclazide, glimepiride) on ventricular ectopic beats as well as the duration of ventricular fibrillation induced by 10 min ischemia/50 min reperfusion in healthy and diabetic rats were compared. Tolbutamide and gliclazide dose-dependently enhanced both parameters both in healthy and diabetic groups. Glibenclamide in healthy rats increased, while in diabetic rats it decreased the arrhythmogenicity. Glimepiride depressed the arrhythmogenicity in both healthy and diabetic animals. Glimepiride proved to dose-dependently enhance the myocardial tissue flow in dog in contrast to glibenclamide. These results confirm that glimepiride has less cardiovascular actions than other sulphonylureas. From the newest oral antidiabetics this review tries to emphasize the most important basic pharmacological properties, mechanism of action, therapeutic use.
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3,385
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Cardiovascular Complications of Neuromuscular Disorders.
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In the past decade, advances in molecular genetics have shown that many familial neuromuscular and cardiovascular diseases share a common pathophysiology. They are caused by inherited mutations in the cellular cytoskeleton of cardiac and skeletal muscle cells. The clinical manifestation of cardiac disease in neuromuscular disorders is common and their management should include both periodic cardiac assessment and appropriate symptomatic and definitive therapy. Dilated cardiomyopathy is a common complication of neuromuscular diseases. Cardiac function may decline progressively as part of the natural history of the disease, but current medical therapy, including angiotensin-converting enzyme inhibitors, beta-blockers, and diuretics, can be used to alleviate symptoms of left ventricular dysfunction. Conduction disturbances may be an important cause of mortality, especially in patients with Emery Dreifuss muscular dystrophy, Kearns-Sayre syndrome, and myotonic dystrophy, and thus pacemaker implantation can be life-saving. Rhythm disturbances, such as atrial fibrillation and ventricular tachyarrhythmias, have been reported in patients with neuromuscular diseases. Treatment is based on preventing sudden death and embolic phenomena and cardioverting or controlling atrial fibrillation. In these patients, problems may arise with anticoagulation and antiarrhythmic therapy due to the inherent locomotor instability associated with the disease, and the presence of concomitant atrioventricular disease. Although uncommon, hypertrophic cardiomyopathy may be a feature of some neuromuscular disorders. Patients should undergo regular risk stratification for sudden cardiac death and symptoms such as heart failure can be treated with medical therapy.
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3,386
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Deterioration of left ventricular function following atrio-ventricular node ablation and right ventricular apical pacing in patients with permanent atrial fibrillation.
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Transcatheter radiofrequency ablation of the atrio-ventricular (AV) node followed by ventricular pacing has been shown to improve symptoms and quality of life of patients with atrial fibrillation (AF). It is assumed that function improves, but this has been less well demonstrated. The aim of this study was to assess the long-term effect of AV node ablation and ventricular pacing on left ventricular ejection fraction (LVEF) in patients with permanent AF.</AbstractText>All 12 patients studied had permanent AF for at least 12 months (mean age 70 years, range 41 to 78). LVEF was determined 6 days and 3 months after AV node ablation by radionuclide ventriculography, at a paced rate of 80 beats . min (-1). Cardiac dimensions were measured by means of transthoracic echocardiography. No major changes in pharmacological therapy were made during 3 months follow-up period. LVEF showed a significant deterioration after 3 months follow-up period for the group (47.5 +/- 14.4%; 6 days after ablation vs 43.2 +/- 13.7%; 3 months after ablation, P < 0.05). There were no significant differences in left ventricular cavity dimensions directly after AV node ablation and 3 months later (LVEDD 51.2 +/- 10.7 mm vs 52.6 +/- 8.6 mm, P = NS: LVESD: 36.1 +/- 14.2 mm vs 36.6 +/- 9.7 mm, P = NS). Left atrial size did not show reduction 3 months after AV node ablation (50.8 +/- 13.6 mm vs 51.0 +/- 14.1 mm, P = NS).</AbstractText>The restoration of a regular ventricular rhythm following AV node ablation for patients in permanent AF does not result in improvement in left ventricular function.</AbstractText>
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3,387
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What is the optimal electrode configuration for atrial defibrillators in man?
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To compare the atrial defibrillation threshold (DFT) for two electrode configurations in patients with drug refractory persistent atrial fibrillation (AF).</AbstractText>11 patients, 73% male, mean age 60.9 (range 38 to 83), underwent implantation of a Medtronic Jewel AF dual chamber defibrillator (model 7250). A step-up atrial DFT was performed in a randomized sequence for two electrode configurations: (1) Right atrial to distal coronary sinus electrode (RA > CS) and (2) defibrillator can to right ventricular and right atrial electrodes (CAN > RV + RA). The RA > CS configuration restored SR in 10 patients (91%). The CAN > RA + RV configuration restored SR in four patients (36%). The mean atrial DFT was significantly lower for the RA > CS than CAN > RA + RV configuration (10 +/- 7 Joules vs 25 +/- 6 Joules), P < 0.01. At 3 months post implantation, AF was reinduced and the protocol was repeated for the optimal electrode configuration. There was no significant difference in the atrial DFT compared with that at implant.</AbstractText>The right atrium to coronary sinus electrode configuration significantly reduces the atrial DFT. The atrial DFT also remains stable at 3 months post-implantation. Patients with persistent AF undergoing insertion of an atrial defibrillator should have a coronary sinus electrode implanted.</AbstractText>
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3,388
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[Sinus node functions, sinoatrial conduction, atrial conductivity after incipient paroxysms of atrial fibrillation and flutter in patients with ischemic heart disease].
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Prediction of the rate of recurrent paroxysms of atrial fibrillation (AF) and flutter (AFl) after the first arrhythmia episode; determination of relevant antiarrhythmic treatment.</AbstractText>157 patients with ischemic heart disease (IHD) complicated by new episodes of AF and AFl entered the study. After the initial episode and 1-2 arrhythmia recurrences all the patients have undergone assessment of hemodynamics, atrial conduction of excitation, sinus node function using transesophageal pacing. The patients were divided into two groups: group 1 consisted of 42 patients having no recurrent paroxysms of AF or AFl for at least 6 months; 115 patients of group 2 had at least one episode of recurrent arrhythmia for 6 months after the first paroxysm.</AbstractText>Patients of group 2 vs those of group 1 had a significantly longer first episode, more frequent occurrence of calcinosis of mitral and/or aortic valve, more serious systolic and diastolic dysfunctions and most frequent retrograde atrial excitation conduction after the first paroxysm.</AbstractText>In detection of only disturbed intraatrial conduction in IHD patients after the first paroxysm of AF and AFl predicted are clinical recurrences of arrhythmia with the recurrence-free period more than 6 months. In retrograde atrial conduction of excitation combined with systolic and diastolic left ventricular dysfunction, sinus node dysfunction prognosis was made of more frequent episodes of AF and AFl.</AbstractText>
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3,389
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Hypertension-related intermyocyte junction remodelling is associated with a higher incidence of low-K(+)-induced lethal arrhythmias in isolated rat heart.
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The aim of this study was to characterise the arrhythmogenic mechanisms involved in hypokalaemia-induced sustained ventricular fibrillation (SVF), in hypertensive rats. The hearts from rats with hypertension induced by the nitric oxide synthase inhibitor L-NAME, and age-matched normotensive controls, were perfused in Langendorff mode with oxygenated Krebs-Henseleit solution followed by a K(+)-deficient solution. In additional experiments, free intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using fura-2 in conjunction with an epicardial optical probe. The epicardial electrocardiogram was continuously monitored during all experiments. The gap junction protein connexin-43 and the ultrastructure of the cardiomyocytes were examined, and selected enzyme activities were measured in situ. There was a higher incidence of low-K(+)-induced SVF in the hearts of hypertensive compared to normotensive rats (83 % vs. 33 %, P < 0.05). Perfusion with a low-K(+)-containing solution lead to elevation of diastolic [Ca(2+)](i) that was accompanied by premature beats, bigeminy, ventricular tachycardia and transient ventricular fibrillation. These events occurred earlier with increased incidence and duration in the hearts of hypertensive rats (arrhythmia scores: hypertensive, 4.9 +/- 0.7; normotensive, 3.1 +/- 0.1; P < 0.05), which exhibited apparent remodelling accompanied by a significant decrease in the density of connexin-43-positive gap junctions. Moreover, low-K(+)-related myocardial changes, including local impairment of intermyocyte junctions, ultrastructural alterations due to Ca(2+) overload and intercellular uncoupling, and decreased enzyme activities were more pronounced and more dispersed in hypertensive than normotensive rats. In conclusion, nitric oxide-deficient hypertension is associated with decreased myocardial coupling at gap junctions. The further localised deterioration of junctional coupling, due to low-K(+)-induced Ca(2+) disturbances, as well as spatial heterogeneity of myocardial alterations including interstitial fibrosis, probably provide the mechanisms for re-entry and sustaining ventricular fibrillation.
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3,390
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Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia.
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Cardiac arrest outside the hospital is common and has a poor outcome. Studies in laboratory animals suggest that hypothermia induced shortly after the restoration of spontaneous circulation may improve neurologic outcome, but there have been no conclusive studies in humans. In a randomized, controlled trial, we compared the effects of moderate hypothermia and normothermia in patients who remained unconscious after resuscitation from out-of-hospital cardiac arrest.</AbstractText>The study subjects were 77 patients who were randomly assigned to treatment with hypothermia (with the core body temperature reduced to 33 degrees C within 2 hours after the return of spontaneous circulation and maintained at that temperature for 12 hours) or normothermia. The primary outcome measure was survival to hospital discharge with sufficiently good neurologic function to be discharged to home or to a rehabilitation facility.</AbstractText>The demographic characteristics of the patients were similar in the hypothermia and normothermia groups. Twenty-one of the 43 patients treated with hypothermia (49 percent) survived and had a good outcome--that is, they were discharged home or to a rehabilitation facility--as compared with 9 of the 34 treated with normothermia (26 percent, P=0.046). After adjustment for base-line differences in age and time from collapse to the return of spontaneous circulation, the odds ratio for a good outcome with hypothermia as compared with normothermia was 5.25 (95 percent confidence interval, 1.47 to 18.76; P=0.011). Hypothermia was associated with a lower cardiac index, higher systemic vascular resistance, and hyperglycemia. There was no difference in the frequency of adverse events.</AbstractText>Our preliminary observations suggest that treatment with moderate hypothermia appears to improve outcomes in patients with coma after resuscitation from out-of-hospital cardiac arrest.</AbstractText>
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3,391
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Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest.
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Cardiac arrest with widespread cerebral ischemia frequently leads to severe neurologic impairment. We studied whether mild systemic hypothermia increases the rate of neurologic recovery after resuscitation from cardiac arrest due to ventricular fibrillation.</AbstractText>In this multicenter trial with blinded assessment of the outcome, patients who had been resuscitated after cardiac arrest due to ventricular fibrillation were randomly assigned to undergo therapeutic hypothermia (target temperature, 32 degrees C to 34 degrees C, measured in the bladder) over a period of 24 hours or to receive standard treatment with normothermia. The primary end point was a favorable neurologic outcome within six months after cardiac arrest; secondary end points were mortality within six months and the rate of complications within seven days.</AbstractText>Seventy-five of the 136 patients in the hypothermia group for whom data were available (55 percent) had a favorable neurologic outcome (cerebral-performance category, 1 [good recovery] or 2 [moderate disability]), as compared with 54 of 137 (39 percent) in the normothermia group (risk ratio, 1.40; 95 percent confidence interval, 1.08 to 1.81). Mortality at six months was 41 percent in the hypothermia group (56 of 137 patients died), as compared with 55 percent in the normothermia group (76 of 138 patients; risk ratio, 0.74; 95 percent confidence interval, 0.58 to 0.95). The complication rate did not differ significantly between the two groups.</AbstractText>In patients who have been successfully resuscitated after cardiac arrest due to ventricular fibrillation, therapeutic mild hypothermia increased the rate of a favorable neurologic outcome and reduced mortality.</AbstractText>
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3,392
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Inhibitory effects of pre-ischemic and post-ischemic treatment with FR 168888, a Na+/H+ exchange inhibitor, on reperfusion-induced ventricular arrhythmias in anesthetized rat.
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Effects of pre-ischemic and post-ischemic treatment with FR 168888 (5-hydroxymethyl-3-(pyrrol-1-yl) benzoylguanidine methanesulfonate), a Na+/H+ exchange inhibitor, on reperfusion-induced ventricular arrhythmias were examined in an ischemia/reperfusion model of anesthetized rat. FR 168888 (0.3 mg/kg) significantly reduced the incidence of ventricular fibrillation (VF) and mortality induced by reperfusion following 5-min coronary occlusion, when it was intravenously administered 5 min before coronary artery occlusion. Post-ischemic treatment with FR 168888 (0.3-10 mg/kg), i.e. given 3 min after the start of occlusion, reduced the incidence of VF and mortality. In order to examine the optimal time of administration, FR 168888 (3 mg/kg) was administered 1 or 3 min after the start of occlusion or immediately before reperfusion. There was no significant difference in the reduction of VF and mortality among the three post-ischemic treatment groups. FR 168888 (3 and 10 mg/kg) significantly increased the blood pressure during ischemia without affecting the heart rate. These results indicate that FR 168888 has antiarrhythmic effects on reperfusion-induced arrhythmias even administered after coronary occlusion.
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3,393
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Mitochondrial gene expression and ventricular fibrillation in ischemic/reperfused nondiabetic and diabetic myocardium.
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We investigated the mitochondrial gene expression related to cardiac function and ventricular fibrillation (VF) in ischemic/reperfused nondiabetic and diabetic myocardium. To identify potentially more specific gene responses we performed subtractive screening, Northern blotting, and reverse transcription-polymerase chain reaction (RT-PCR) of mitochondrial genes expressed after 30 min ischemia followed by 120 min reperfusion in isolated rat hearts that showed VF or did not show VF. Cytochrome oxidase B subunit III (COXBIII) and ATP synthase subunit 6, studied and selected out of 40 mitochondrial genes by subtractive screening, showed an expression after 30 min ischemia (no VF was recorded) in both nondiabetic and diabetic subjects. Upon reperfusion, the down-regulation of these genes was only observed in fibrillated hearts. Such a reduction in signal intensity was not seen in nonfibrillated myocardium. In additional studies, nondiabetic and diabetic hearts, without the ischemia/reperfusion protocol, were subjected to electrical fibrillation, and a significant reduction in COXBIII and ATPS6 mRNA signal intensity was observed indicating that VF contributes to the down-regulation of these genes. Cardiac function (heart rate, coronary flow, aortic flow, left ventricular developed pressure) showed no correlation between the up- and down-regulation of these mitochondrial genes in both nondiabetic and diabetic ischemic/reperfused myocardium. Our data suggest that COXBIII and ATPS6 may play a critical role in arrhythmogenesis, and the stimulation of COXBIII and ATPS6 mRNA expression may prevent the development of VF in both nondiabetic and diabetic ischemic/reperfused myocardium.
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3,394
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Outcome studies with device therapy in patients with heart failure.
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Heart failure is a common debilitating condition for which pharmacologic therapy thus far has provided only partial relief. Despite, and sometimes because of, medical therapy, the overall prognosis remains poor, with high rates of sudden death and death from progressive heart failure. Device-based therapies offer considerable promise for relief of symptoms and for improving prognosis. It is clear that implantable defibrillators should be considered for patients with heart failure who have been resuscitated from ventricular fibrillation or sustained ventricular tachycardia. Several large studies currently are investigating the effects of implantable defibrillators on total mortality in patients with major left ventricular systolic dysfunction but without other risk factors for sudden death. Cardiac resynchronization is a promising new therapy that may relieve the symptoms of heart failure in appropriately selected patients resistant to optimal pharmacologic therapy. Two large trials (CARE-HF and COMPANION) currently are investigating the effects of cardiac resynchronization therapy (CRT) on morbidity and mortality. It is important that those involved in these trials enroll patients quickly and minimize device implantation into patients who have not been assigned this therapy (cross-overs). Overenthusiasm for the benefits that doctors believe devices might bring could destroy the future basis for our clinical practice, denying future generations of patients and the doctors themselves access to what they believe to be effective treatments.
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3,395
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Future of device therapy for arrhythmias.
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During the last three decades, implantable devices have been developed that are able to treat complex arrhythmias on an individualized basis, with emphasis on rapid restoration of normal cardiac rhythm or creation of the best physiologic alternative. Currently, new areas for device therapy include atrial fibrillation, life-threatening ventricular arrhythmias (with or without heart failure), and out-of-hospital sudden death. To improve resuscitation from circulatory arrest, the development and widespread use of dependable devices continuously registering cardiac rhythm and able to localize the victim are needed to shorten the time interval to successful defibrillation.
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3,396
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[Cardiac arrest in dental offices. Report of six cases].
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The extreme medical emergency situation in the dental setting is cardiac arrest. The need to provide dental treatment to the medically compromised patients, suffering from very high risk heart diseases at special oral medicine hospital dentistry units, expose the dental and medical teams to the possibility of patients' death. Cardiac and cardiorespiratory arrest in these units faces the dentists with the need to perform basic and/or advanced cardiopulmonary resuscitation (CPR). Various etiologies are responsible for cardiac arrests. This article describes our experience and the outcome of six patients who have suffered cardiac arrests pre, during or post dental treatment in two special oral medicine centers. Two patients, suffering from severe congestive heart failure experienced fatal ventricular arrhythmia, both of them underwent CPR with early cardiac defibrillation, following which one patient completely recovered, and the other one expired. Two young and healthy patients experienced severe neurocardiogenic syncope with heart standstill for more than 40 seconds followed by spontaneous uneventful recovery. The fifth patient, who suffered from ventricular fibrillation as a result of an acute coronary ischemia, was resuscitated successfully. The last patient, a young woman, suffered from a severe status epilepticus causing bradycardia, which led to cardiac arrest, but recovered following CPR. All patients who did not recover spontaneously underwent methodical advanced CPR with early defibrillation. Only one patient out of the six died.
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3,397
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[Utility of cardiac event recorders in diagnosing arrhythmic etiology of palpitations in patients without structural heart disease].
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To determine the diagnostic yield of transtelephonic event monitors for identifying the reason for palpitations in patients with no structural heart disease.</AbstractText>For 20 months we enrolled all patients reporting palpitations in whom heart disease had been ruled out by medical history, physical examination, ECG and transthoracic echocardiography. All patients underwent 24 h Holter monitoring, which did not provide diagnostic information. Later, a Cardiotest 4DM transtelephonic event monitor was provided to each patient for a mean of 15 3 days. We used SPSS V 10 for statistical analysis.</AbstractText>Two hundred twenty-seven consecutive patients were enrolled. Mean age was 45 3 years (range 12-85); 167 were females (74%). Two hundred twelve of the 227 patients (93.3%) experienced palpitations while wearing the device, and 210 (92.5%) used the monitor correctly, recording the cardiac rhythm during palpitations. Fifteen patients (6.6%) had no palpitations during the days of study. In 125 (55%) the Cardiotest 4DM correctly recorded and transmitted arrhythmia that justified the patients' reference to palpitations. In 35 (15.4%) significant arrhythmia was detected: paroxysmal supraventricular tachycardia in 21, atrial fibrillation in 9, atrial flutter in 5, runs of ventricular extrasystoles in 4 and right outflow tract ventricular tachycardia in 1. Sinus rhythm was recorded during palpitations in 85 patients (37%), and arrhythmia as the cause could be ruled out.</AbstractText>Cardiotest 4DM identifies arrhythmia in a very high proportion of patients with palpitations and no structural heart disease.</AbstractText>
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3,398
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Dilated cardiomyopathy in Presa canario dogs: ECG findings.
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Forty-seven Presa canario dogs were diagnosed with congestive heart failure due to dilated cardiomyopathy (DCM). Supraventricular or ventricular tachydysrhythmias were found in 29 dogs. Atrial fibrillation was the most common dysrhythmia. Ventricular dysrhythmias were observed infrequently and had a very important prognostic value in Presa canario dogs with DCM. Abnormalities of cardiac conduction were diagnosed in 16 (34%) dogs and changes in wave morphology were found in 29 (62%) dogs. Normal sinus rhythm was recorded in only 12 (26%) Presa canario dogs with DCM.
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3,399
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Continuous antegrade blood cardioplegia: cold vs. tepid.
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Continuous antegrade blood cardioplegia (CABCP) is used at different temperatures. We investigated the consequences of CABCP at 6 degrees C (COLD) vs. 28 degrees C (TEPID).</AbstractText>Anesthetized open-chest pigs (25 +/- 2 kg) were placed on cardiopulmonary bypass (CPB). The hearts were arrested for 30 min by 6 degrees C cold or 28 degrees C tepid CABCP (n = 8 each). After an initial 3 min antegrade application of high potassium (20 mEq) cold (6 degrees C) blood cardioplegia, the hearts were arrested for a subsequent 27 min by normokalemic blood delivered antegrade at either 6 degrees C or 28 degrees C. After this, the hearts underwent perfusion with warm systemic blood for an additional 30 min on CPB. Biochemical cardiac data (MVO2 [ml/min/100 g], release of creatine kinase [CK U/min/100 g] and lactate [mg/min/100 g]) were measured during CPB. Total tissue water content (%) and left ventricular stroke work index (SWI g x m/kg) were determined 30 min after discontinuation of CPB and compared to pre-CPB controls.</AbstractText>Cold CABCP kept all hearts continuously arrested. The COLD hearts showed no biochemical or functional disturbance. The TEPID hearts intermittently fibrillated and required additional high potassium BCP shots. The TEPID hearts showed a marked CK leakage (2.6 +/- 0.4 vs. 0.7 +/- 0.4), lactate production (4.0 +/- 1.6 vs. extraction from the COLD group) despite the non-ischemic protocol, an impaired initial oxygen consumption (4.2 +/- 1.3 vs. 7.1 +/- 1.6) at the end of cardiac arrest, the formation of myocardial edema (79.5 +/- 1.0 vs. 77.0 +/- 0.8), and a depressed recovery of SWI (0.69 +/- 0.15 degrees vs. 1.41 +/- 0.13). *p < 0.05 for comparison of TEPID vs. COLD hearts using Student's t-test for unpaired data; degrees p < 0.05 for intergroup-comparison of TEPID vs. COLD vs. controls using ANOVA adjusted for repeated measures.</AbstractText>Uninterrupted cardioplegia can be safely performed with cold normokalemic CABCP. In contrast, tepid normokalemic CABCP leads to fibrillation, jeopardizes the heart, and should be avoided.UND</AbstractText>
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