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7,400 | Specific and gender differences between hospitalized and out of hospital mortality due to myocardial infarction. | In this paper, the authors evaluate gender related differences of myocardial infarction mortality before and after hospital admittance. Myocardial infarction mortality in the Clinical Hospital Split in the seven years period between 2000 and 2006, have been analyzed together with out of hospital sudden death patients with acute myocardial infarction established during autopsy. During the seven year period between 2000 and 2006, 3434 patients were treated for myocardial infarction in the Split Clinical Hospital, 2336 (68%) males and 1098 (32%) females with a 12% total mortality (427 patients). The annual number of hospitalized persons has been increasing during that period (474 in yr. 2000 us. 547 in yr. 2006), while mortality decreased from 15% in 2000 to 9.6% in 2006. Female patients had significantly higher hospital mortality than male patients, (228 or 21% vs. 202 or 9%, p<0.05). Women also had significantly higher total AMI mortality (23.7% vs. 15,7%, p <0.05). Anterior myocardial infarction with ST elevation in precordial leads had significantly higher mortality (19%) compared to patients with lateral (11%), inferior (10%) myocardial infarction with ST elevation and also NSTEMI (4%) mortality p<0.05. Female patients more frequently die in hospital, 84% (230) than out of hospital 16% (43). From the total number of AMI deaths (388) in male patients, 56% (217) were in hospital and 44% (171) out of hospital (p<0.001). Men had significantly higher prehospital mortality rate than women (81% vs. 19%, p<0.05). Men also more frequently died from ventricular fibrillation (22% vs. 10%, p<0.05), while women died more frequently of heart failure, cardiogenic shock, and myocardial rupture (33% vs. 15% p<0.05). Regarding the total number of deaths from myocardial infarction men had significantly higher prehospital mortality compared to women (178 or 7.3% vs. 43 or 3.7%, p<0.05). Anterior myocardial infarction had a significantly higher rate in patients dying pre-hospital (58%), in contrast to inferior (36%) and lateral myocardial infarction with ST elevation (6%) p<0.05. We have concluded that male patients die more frequently within the first few hours of AMI mostly due to malignant arrhythmias, while female patients died in sub acute stage due to heart failure while being hospitalized. Nevertheless total mortality of AMI remains significantly higher in women. |
7,401 | Superiority of biphasic over monophasic defibrillation shocks is attributable to less intracellular calcium transient heterogeneity. | The purpose of this study was to test the hypothesis that superiority of biphasic waveform (BW) over monophasic waveform (MW) defibrillation shocks is attributable to less intracellular calcium (Ca(i)) transient heterogeneity.</AbstractText>The mechanism by which BW shocks have a higher defibrillation efficacy than MW shocks remains unclear.</AbstractText>We simultaneously mapped epicardial membrane potential (Vm) and Ca(i) during 6-ms MW and 3-ms/3-ms BW shocks in 19 Langendorff-perfused rabbit ventricles. After shock, the percentage of depolarized area was plotted over time. The maximum (peak) post-shock values (VmP and Ca(i)P, respectively) were used to measure heterogeneity. Higher VmP and Ca(i)P imply less heterogeneity.</AbstractText>The defibrillation thresholds for BW and MW shocks were 288 +/- 99 V and 399 +/- 155 V, respectively (p = 0.0005). Successful BW shocks had higher VmP (88 +/- 9%) and Ca(i)P (70 +/- 13%) than unsuccessful MW shocks (VmP 76 +/- 10%, p < 0.001; Ca(i)P 57 +/- 8%, p < 0.001) of the same shock strength. In contrast, for unsuccessful BW and MW shocks of the same shock strengths, the VmP and Ca(i)P were not significantly different. The MW shocks more frequently created regions of low Ca(i) surrounded by regions of high Ca(i) (post-shock Ca(i) sinkholes). The defibrillation threshold for MW and BW shocks became similar after disabling the sarcoplasmic reticulum (SR) with thapsigargin and ryanodine.</AbstractText>The greater efficacy of BW shocks is directly related to their less heterogeneous effects on shock-induced SR Ca release and Ca(i) transients. Less heterogeneous Ca(i) transients reduces the probability of Ca(i) sinkhole formation, thereby preventing the post-shock reinitiation of ventricular fibrillation.</AbstractText> |
7,402 | Constrictive pericarditis impressing and narrowing the ascending aorta. | A 77-year-old male patient was admitted to our institution with 1-year history of progressive dyspnea on exertion, and lower extremity edema. His chest x-ray showed a circumferential pericardial calcification and right-sided pleural effusion. The electrocardiography revealed atrial fibrillation with low voltage in all derivations and diffuse nonspecific T-wave inversions. The transesophageal echocardiography showed a thickened pericardium with biatrial enlargement and normal right and left ventricular systolic functions. A thick echogenic structure that caused impression and narrowing of the ascending aorta was observed. Simultaneous right and left heart catheterization showed elevation and equalization of right-sided and left-sided diastolic filling pressures, with characteristic dip and plateau. Aortic angiogram showed the ascending aorta was impressed and narrowed by calcified pericardium. Cine magnetic resonance imaging showed pericardial calcifications impressing and narrowing of the ascending aorta. All these findings were consistent with constrictive pericarditis. The patient had no history of tuberculosis, cardiac surgery, or mediastinal irradiation. His HIV antibody test was negative. Marked pericardial thickening and calcifications were evident during pericardiectomy. Histological analysis of the pericardium showed dense collageneous matrix, mild chronic inflammation and calcification. The culture of pericardial tissue revealed no identifiable cause including tuberculosis. The patient was diagnosed as idiopathic constrictive pericarditis. The patient's symptoms and edema decreased remarkably after pericardial stripping. He remained well at 1-year follow-up. |
7,403 | Predictors of secondary tricuspid regurgitation after left-sided valve replacement. | To evaluate the risk factors of tricuspid regurgitation (TR) after left-sided valve replacement (LSVR) and plan the initial surgical treatment of TR.</AbstractText>Two hundred and forty-eight patients, including 217 patients in the LSVR group and 31 patients in the LSVR+DeVega group, were followed up. A retrospective analysis was performed on 14 characteristics in the LSVR group. Variables were used to evaluate predictors of TR progression after single LSVR by either a univariate or multivariate analysis. DeVega's tricuspid annuloplasty was evaluated on progress of TR by univariate analysis.</AbstractText>The mean follow-up was 5.2 +/- 2.9 (range, 3-16) years after surgery. In a univariate analysis, atrial fibrillation, huge left atrium, long time from onset to surgery, tricuspid rheumatic changes, preoperative +2 or +3 TR, the degradation of left ventricular ejection fraction, augmented right atrium, and single mitral valvular disease were significant risk factors for TR development. A multivariate analysis indicated that the four items mentioned above were statistically significant predictors of TR after surgery. The progress of TR in the LSVR+DeVega group was significantly less than in the LSVR group.</AbstractText>An aggressive repair of accompanying TR should be performed at the time of initial surgery in patients with a huge left atrium, atrial fibrillation, long time from onset to surgery, or tricuspid rheumatic changes. DeVega's tricuspid annuloplasty therefore helps prevent a progression of TR.</AbstractText> |
7,404 | Brugada syndrome in an active duty Air Force senior pilot. | Brugada syndrome describes a subgroup of patients at risk for polymorphic ventricular tachycardia, ventricular fibrillation, and sudden cardiac death and is likely underdiagnosed among aviators.</AbstractText>A 40-year-old male pilot presented to the clinic for his physical. He denied any symptoms on initial questioning. Subsequent electrocardiogram (ECG) revealed premature ventricular couplets with ST-segment elevation in V1 and V2 of the precordial leads with T-wave abnormalities.</AbstractText>Special care must be taken if ECG demonstrates a Brugada pattern-especially in patients with a history of syncope or a family history of sudden death. Recent studies have confirmed a significant risk reduction in symptomatic patients with type 1 Brugada to as low as 0.8% to 3% with an implantable cardioverter defibrillator.</AbstractText>Symptomatic patients displaying type 1 Brugada ECG (spontaneous or after sodium channel blockade) should receive an implantable cardioverter defibrillator and must be permanently disqualified. The Aeromedical Consultation Service should review all cases of Brugada syndrome and render a return to fly for asymptomatic nondiagnostic Brugada types.</AbstractText> |
7,405 | Induced ion currents and the endothelin pathway as targets for anti-arrhythmic agents. | The development of novel anti-arrhythmic drugs is necessary, specifically agents that do not cause torsades de pointes (Tdp). Ion channelopathy that is involved in mechanisms underlying sudden cardiac death (SCD) includes both ion channels in the membrane, and the calcium-releasing channels and the calcium uptake process in the sarcoplasmic reticulum. Advances in the understanding of abnormalities of ion channels in the myocardium caused by congenital defects or by a failing heart and cardiomyopathy offer further insights into the relationship between channelopathy and SCD. Enhanced L-type Ca2+ current (ICa.L) activity has been detected in the hearts of patients with a mutation of the Cav1.2 gene; these patients exhibit a high risk of SCD. Rats with thyroxin-induced cardiomyopathy demonstrate an increase in ICa.L activity that is responsible for exacerbated ventricular fibrillation (VF). This is suppressed by propranolol or CPU-86017, a class III anti-arrhythmic agent with potent antioxidant activity. Interestingly, an increase in rapidly (IKr) and slowly (IKs) activating delayed rectifying K+ currents is caused by gain-of-function mutations of the KCNH2 and KCNQ1 genes, respectively, in patients with short QT syndrome (SQT). Increased IKr and IKs, which are associated with exacerbated VF, are also found in models of thyroxin-induced cardiomyopathy and are suppressed by CPU-86017. ICa.L, IKr and IKs can also be induced in cardiomyocytes when incubated with isoproterenol. A reversal of upstream lesions by an endothelin receptor antagonist CPU-0213 provides suppression of ventricular tachyarrhythmias and upregulates FK506 binding protein 12.6. CPU-86017 and its chiral isomer SR-CPU-86017 relieve upstream lesions, with mild suppression of IKr and moderate suppression of IKs and ICa.L. These agents may be promising as anti-arrhythmic agents that produce less Tdp tachyarrhythmias. |
7,406 | Sibutramine-associated QT interval prolongation and cardiac arrest. | To report on a probable association between sibutramine and QT interval prolongation leading to ventricular fibrillation and cardiac arrest.</AbstractText>A previously well 51-year-old woman with obesity but no other relevant past medical history or cardiac risk factors was prescribed sibutramine (initial dose 10 mg daily, increased to 15 mg daily after 10 wk). Four months after initiation of therapy, the woman developed ventricular fibrillation and was successfully resuscitated. On admission, an electrocardiogram (ECG) demonstrated sinus tachycardia without any ischemic changes and a prolonged QTc interval (545 msec). A subsequent coronary angiogram revealed normal coronary arteries and no other abnormalities. Her QTc interval returned to normal (432 msec) by day 2 and remained within normal limits (<440 msec) thereafter. Due to a favorable neurologic recovery and the absence of any cardiac structural abnormality, the patient was readmitted for implantation of an automatic implantable cardioverter-defibrillator on day 35 and remained well from a cardiac and neurologic standpoint at a 2-year follow-up examination.</AbstractText>Sibutramine acts centrally to inhibit noradrenaline, dopamine, and serotonin reuptake, thereby sharing similar actions of other QT interval-prolonging drugs. Therefore, sibutramine might be anticipated to also share a tendency to QT interval prolongation. The current prescribing information for sibutramine does not specifically list any precautions or adverse reactions related to QT interval prolongation. QT interval prolongation associated with sibutramine in this case is considered probable based on the Naranjo probability scale.</AbstractText>Clinicians prescribing sibutramine should monitor their patients for ECG abnormalities and be cautious in coprescribing drugs known to prolong the QT interval.</AbstractText> |
7,407 | Dynamic mechanism for initiation of ventricular fibrillation in vivo. | Dynamically induced heterogeneities of repolarization may lead to wave-front destabilizations and initiation of ventricular fibrillation (VF). In a computer modeling study, we demonstrated that specific sequences of premature stimuli maximized dynamically induced spatial dispersion of refractoriness and predisposed the heart to the development of conduction block. The purpose of this study was to determine whether the computer model results pertained to the initiation of VF in dogs in vivo.</AbstractText>Monophasic action potentials were recorded from right and left ventricular endocardium in anesthetized beagle dogs (n=11) in vivo. Restitution of action potential duration and conduction time and the effective refractory period after delivery of the basic stimulus (S(1)) and each of 3 premature stimuli (S(2), S(3), S(4)) were determined at baseline and during verapamil infusion. The effective refractory period data were used to determine the interstimulus intervals for a sequence of 4 premature stimuli (S(2)S(3)S(4)S(5)=CL(VF)) for which the computer model predicted maximal spatial dispersion of refractoriness. Delivery of CL(VF) was associated with discordant action potential duration alternans and induction of VF in all dogs. Verapamil decreased spatial dispersion of refractoriness by reducing action potential duration and conduction time restitution in a dose-dependent fashion, effects that were associated with reduced inducibility of VF with CL(VF).</AbstractText>Maximizing dynamically induced spatial dispersion of repolarization appears to be an effective method for inducing VF. Reducing spatial dispersion of refractoriness by modulating restitution parameters can have an antifibrillatory effect in vivo.</AbstractText> |
7,408 | Early sustained ventricular arrhythmias complicating acute myocardial infarction. | Sustained ventricular arrhythmias complicate 2% to 20% of acute myocardial infarctions (MIs) and are associated with increased in-hospital mortality. However, it remains unclear whether successful mechanical revascularization improves outcomes in these patients. The objective of this analysis was to identify predictors of sustained ventricular arrhythmias after acute MI and to determine the influence of successful revascularization on in-hospital mortality.</AbstractText>We conducted a retrospective cohort study of all patients who underwent percutaneous coronary intervention for acute MI in New York State between 1997 and 1999.</AbstractText>Of the 9015 patients who underwent percutaneous coronary intervention for acute MI, 472 (5.2%) developed sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) before revascularization. After multivariable adjustment, independent predictors of sustained VT/VF included cardiogenic shock (odds ratio [OR], 4.10; 95% confidence interval [CI], 3.20-5.58; P <.001), heart failure (OR, 2.86; 95% CI, 2.24-3.67: P <.001), chronic kidney disease (OR, 2.58; 95% CI, 1.27-5.23; P=.009), and presentation within 6 hours of symptom onset (OR, 1.46; 95% CI, 1.18-1.81; P=.001). Patients with sustained VT/VF had greater in-hospital mortality (16.3% vs 3.7%, P <.001). Although successful percutaneous coronary intervention was associated with decreased in-hospital mortality in patients with VT/VF (P <.001), patients with sustained VT/VF and successful revascularization experienced increased mortality compared with patients without sustained ventricular arrhythmias (P <.001).</AbstractText>Among patients undergoing percutaneous coronary intervention for acute MI, sustained VT/VF remains a significant complication associated with a 4-fold increased risk of in-hospital mortality. Early mortality is reduced after successful percutaneous coronary intervention, but remains elevated in this high-risk group.</AbstractText> |
7,409 | Paroxysmal ventricular tachycardia and paroxysmal atrial fibrillation associated with subclinical hyperthyroidism, chronic renal failure and elevation of prostate-specific antigen during acute myocardial infarction. | Subclinical hyperthyroidism is an increasingly recognized entity that is defined as a normal serum free thyroxine and free triiodothyronine levels with a thyroid-stimulating hormone level suppressed below the normal range and usually undetectable. Paroxysmal atrial fibrillation is a frequent complication of acute myocardial infarction. It has been reported that subclinical hyperthyroidism is not associated with coronary heart disease or mortality from cardiovascular causes but it is sufficient to induce arrhythmias including an increase in atrial fibrillation rate. It has also been reported that increased factor X activity in patients with subclinical hyperthyroidism represents a potential hypercoagulable state. Moreover chronic renal failure presents an increased arrhythmic risk. Apparently spurious result has been reported in a work about mean serum prostate-specific antigen (PSA) concentration during acute myocardial infarction with mean serum PSA concentration significantly lower on day 2 than either day 1 or day 3 and it has been reported that these preliminary results could reflect several factors, such as antiinfarctual treatment, reduced physical activity or an acute-phase response. We present a case of paroxysmal ventricular tachycardia and paroxysmal atrial fibrillation associated with subclinical hyperthyroidism, chronic renal failure and elevation of serum PSA concentration in a 90-year-old Italian man during acute myocardial infarction. Also this case focuses attention on the importance of a correct evaluation of subclinical hyperthyroidism and of chronic renal failure. Moreover, our report also confirms previous findings and extends the evaluation of PSA during acute myocardial infarction. |
7,410 | Coupled pacing reverses the effects of persistent atrial fibrillation on the left ventricle. | Recent studies have demonstrated that ventricular rate control is a viable treatment strategy for patients in atrial fibrillation (AF). The purpose of this study was to determine whether or not the benefits of coupled pacing (ie, a proposed rate control therapy) could be used during persistent AF.</AbstractText>Six mongrel dogs were chronically implanted with endocardial atrial and ventricular pacemaker leads and two standard dual-chamber pacemakers. With the use of two custom "Y"-lead adapters, the pacemakers were used to induce AF and to apply coupled pacing. Left ventricular end-diastolic and systolic volumes were measured by echocardiography to determine ejection fractions.</AbstractText>Persistent AF significantly increased both ventricular rate and left ventricular dimensions. After sustained coupled pacing had been applied for 3 to 4 weeks, left ventricular volumes and contractile rate were significantly reduced and returned toward the values measured prior to the induction of persistent AF. Coupled pacing increased the ejection fraction that had been reduced by persistent AF.</AbstractText>Coupled pacing reversed the left ventricular remodeling caused by the tachycardia resulting from AF.</AbstractText> |
7,411 | Arrhythmia surgery in patients with and without congenital heart disease. | Arrhythmia surgery has favorably impacted the clinical course of debilitating atrial and ventricular arrhythmias in patients with and without congenital heart disease. This study reviews arrhythmia mechanisms and documents long-term outcome of patients undergoing arrhythmia operations alone or associated with congenital heart repairs. The analysis excludes Fontan conversion patients.</AbstractText>Between 1987 and 2007, arrhythmia operations were done in 11 patients without associated congenital heart disease and in 89 along with congenital heart repairs. Mean age was 15.9 +/- 12.5 years (range, 7 days-48 years); 7 were infants (mean age, 23 +/- 16 days). Resternotomy was performed in 65 (65%). Two functional ventricles were present in 67 patients; 33 had 1 functional ventricle. Arrhythmias included macro-reentrant atrial tachycardia in 45, atrial fibrillation in 11, accessory connections in 19, atrioventricular nodal reentry tachycardia in 6, focal atrial tachycardia in 6, and ventricular tachycardia in 13.</AbstractText>Operative mortality was 3 (3.0%) due to advanced associated congenital heart disease. There were 4 late deaths (4.0%) and 2 late cardiac transplants (2.0%). Freedom from arrhythmia recurrence at 1 and 10 years was 94% and 85% for atrial arrhythmias, and 85% and 68% for ventricular arrhythmias, respectively.</AbstractText>Successful surgical therapy for atrial arrhythmias can be performed safely with a high freedom from recurrence rate in patients with and without associated congenital heart disease. Surgical ablation for ventricular arrhythmias is less predictive. Complexity of the underlying congenital heart disease and hemodynamic status may contribute to potential arrhythmia recurrence or new onset arrhythmia manifestation.</AbstractText> |
7,412 | Long-term assessment of electrocardiographic and echocardiographic findings in Norwegian elite endurance athletes. | The long-term outcome and clinical significance of athlete's heart has been debated and more longitudinal data are needed. We present a prospective 15 years' follow-up study of ECG and echo findings in elite endurance athletes following the end of their competitive career.</AbstractText>Clinical evaluation, ECG, ambulatory Holter recording and echocardiography were performed in 30 top-level endurance athletes with a mean age of 24 years with follow-up 15 years later. All had then ended their competitive career, but still performed recreational sports activities.</AbstractText>No clinical events were reported. Average resting heart rate was unchanged (53.5 +/- 10 at baseline and 55.4 +/- 11 at follow-up, p = n.s.), complex ventricular arrhythmias did not occur and the number of ventricular premature beats (VPBs) were 0.4 +/- 0.8/h at baseline and 3.8 +/- 10/h at follow-up (p = n.s.). In a subgroup of 4 subjects with >100 VPBs per hour at follow-up left ventricular mass was increased compared to the others (p < 0.03). Furthermore, regression of sino-atrial (SA) and atrioventricular (AV) blocks was shown. There were no cases of atrial flutter or fibrillation. There was a slight reduction in mean left ventricular wall thickness (9.9 +/- 1.2 vs. 9.5 +/- 1.4 mm, p < 0.05) and a highly significant reduction of relative wall thickness (0.38 vs. 0.35, p < 0.001). Left ventricular end-diastolic volume (68 +/- 6 vs. 70 +/- 7 ml ml/m(2), p = n.s.) and left ventricular mass (109 +/- 19 vs. 107 +/- 19 g/m(2), p = n.s.) were unchanged when corrected for body surface area and ejection fraction (EF) increased (60 +/- 7 vs. 67 +/- 6%, p < 0.01). Parameters of left ventricular diastolic function were normal both at baseline and follow-up.</AbstractText>There was no evidence of deleterious cardiac effects of previous top-level endurance athletic activity at 15 years' follow-up.</AbstractText>Copyright 2008 S. Karger AG, Basel.</CopyrightInformation> |
7,413 | Functional tricuspid regurgitation in patients with pulmonary hypertension: is pulmonary artery pressure the only determinant of regurgitation severity? | Pulmonary hypertension is a common cause of functional tricuspid regurgitation (TR), but other factors play a role in determining TR severity. The objectives of our study were to determine the distribution of TR severity in relation to pulmonary artery systolic pressure (PASP) and to define the determinants of TR severity.</AbstractText>The echocardiographic reports and selected echocardiographic studies of patients with echocardiographic estimation of PASP were reviewed. Patients with organic tricuspid valve (TV) disease were excluded from the analysis.</AbstractText>Among 2,139 patients, the frequency of moderate or severe TR was progressively greater in patients with higher PASP. Nevertheless, TR was only mild in a substantial proportion of patients with high PASP (mild TR in 65.4% of patients with PASP 50-69 mm Hg and in 45.6% of patients with PASP >or= 70 mm Hg). By multivariate analysis, age, female gender, PASP (odds ratio, 2.26 per 10-mm Hg increase; 95% confidence interval, 1.95 to 2.61), pacemaker lead, right atrial (RA) and right ventricular enlargement, left atrial enlargement, and organic mitral valve disease were independently associated with greater degrees of TR. In patients with PASP >or= 70 mm Hg, RA size, tricuspid annular diameter, and TV tethering area were greater in patients with greater degrees of TR.</AbstractText>PASP is a strong determinant of TR severity, but many patients with pulmonary hypertension do not exhibit significant TR. In addition to PASP, demographic characteristics, mechanical factors, remodeling of the right heart cavities, and other factors (possibly reflecting the presence of atrial fibrillation or occult organic TV disease) are predictive of TR severity.</AbstractText> |
7,414 | National Registry on Cardiac Electrophysiology--2006. | Clinical electrophysiology is one of the areas of cardiology that has seen most growth in Portugal, particularly in interventional cardiology, which includes ablation of arrhythmias and prevention of sudden cardiac death. The annual publication of a national registry enables us to assess qualitative and quantitative progress, compare our results with international data, assess the centers' training capabilities and inform health authorities of the activities and needs of the sector. The authors analyze the number and type of procedures performed during 2006 based on a survey sent to 19 national centers (15 public and 4 private) that performed diagnostic and interventional electrophysiology (15 centers) and/or implanted cardioverter-defibrillators (ICDs) (19 centers) in that year. The number of electrophysiology centers remained unchanged from 2005, but four new centers began implanting ICDs in 2006. In the year under review, 1805 electrophysiological studies were performed, 75.3% of which were followed by ablation therapy, a total of 1360 ablation procedures (a 22.3% increase over the previous year). Accessory pathways were the main indication for ablation (32%), followed by atrial flutter (25%), atrioventricular nodal reentrant tachycardia (23%), atrial fibrillation (10%), ventricular tachycardia (5%), atrial tachycardia (3%) and atrioventricular junction ablation (2%). In 2006, a total of 738 ICD devices were implanted, of which 64 were battery replacements and 674 were first implantations, with the following distribution: 346 single chamber (51.3%), 98 dual chamber (14.5%) and 230 integrated in ventricular resynchronization systems (34.1%). These figures reflect a lower growth rate than that of 2005, even though in 2006 first implantations rose from 54.7 to 67.4 devices per million population. The ICD implantation rate in Portugal is still far below the European average, which means there is a continuing need to raise awareness of this therapeutic option among the Portuguese medical community. With regard to the training capabilities currently available in Portugal, only 5 centers (all public) had a sufficient level of activity to fulfill the requirements stipulated for the subspecialty of cardiac electrophysiology. As for implantation of ICDs, 12 centers implanted more than 10 units, the minimum annual curricular limit for this subspecialty. |
7,415 | Selective site pacing: rationale and practical application. | Although it has become traditional to place permanent pacemaker leads at the right ventricular apex and right atrial appendage, pacing from these locations poorly mimics normal physiology. A growing evidence base shows that right ventricular apical pacing results in ventricular dyssynchrony and various adverse effects. Provocative data from early trials suggest that pacing from alternate sites in the right ventricle--His bundle pacing, para-Hisian pacing, septal right ventricular outflow tract pacing, and right ventricular midseptal pacing--may lead to improved results. Similarly, early data suggest that right atrial pacing near Bachmann's bundle may lead to superior outcomes when compared with pacing from the right atrial appendage. Several large-scale, randomized clinical trials are now under way to establish the future role of selective site pacing. |
7,416 | Short-coupled variant of torsade de pointes. | A 36-year-old man with a history of primary sclerosing cholangitis and epilepsy was admitted to our hospital for cholangitis. During admission he was resuscitated because of ventricular fibrillation. ECGs showed multiple ventricular premature beats (VPBs) with a short coupling interval (240 ms), resulting in frequent torsade de pointes (TdP). In total, the patient had to be defibrillated 12 times. Short-coupled TdP is a rare variant of polymorphic ventricular tachycardia, with unknown aetiology. Verapamil seems to be the only drug able to suppress the arrhythmia. Verapamil, however, does not lower the risk of sudden death; therefore, an ICD implantation is advised. (Neth Heart J 2008;16:246-9.). |
7,417 | Recurrence of cardiac arrest after 14 years without ICD interventions: a VF cluster immediately after delivery. | One day after childbirth, a 29-year-old woman had several episodes of polymorphic ventricular tachycardia and ventricular fibrillation. She was rescued by an internal cardioverter defibrillator (ICD) which she had received 14 years ago, after out-of-hospital cardiac arrest, without recurrences until now. The electrocardiogram showed a normal QT interval, and ventricular premature beats, which seemed to arise from the same site. This case report illustrates that, even after years with freedom of ICD therapy, depleted devices still have to be replaced. (Neth Heart J 2008;16:242-5.). |
7,418 | Aborted sudden cardiac death in a 52-yearold man without structural heart disease. | Sudden cardiac death in the absence of apparent structural heart disease is an uncommon phenomenon. The majority of these patients do not have 'normal' hearts and specific diagnostic tools are required to identify structural or functional abnormalities. We describe the history of a 50-yearold man who survived ventricular fibrillation. Clinical investigation, including a coronary angiography and electrophysiological study, appeared to be normal. An implantable cardioverter defibrillator was inserted. Follow-up Holter monitoring was performed after a recurrent episode of ventricular tachycardia. It demonstrated transient ST-segment elevation. An acetylcholine provocation test was subsequently carried out. Reversible coronary spasm of the left descending coronary artery was found, during which a diagonal branch was occluded. It may be concluded that coronary spasm provocation is of value in the routine diagnostic work-up of patients surviving sudden cardiac death without apparent heart disease. (Neth Heart J 2008;16:239-41.). |
7,419 | Treatment of atrial fibrillation and atrial flutter: Part II. | Atrial fibrillation (AF) is often complicated by a life-threatening ventricular response, and emergency electrocardioversion and/or drug therapy to reduce the rapid ventricular rate may be necessary. However, patients with AF and Wolff-Parkinson-White syndrome should not be given digoxin or calcium channel blockers. Elective direct current (DC) cardioversion has a higher success rate and a lower incidence of cardiac adverse effects than does medical cardioversion in converting AF to sinus rhythm. Unless transesophageal echocardiography has shown no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective direct current or drug cardioversion of AF and continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer, especially in older patients, ventricular rate control plus warfarin rather than maintaining sinus rhythm with antiarrhythmic drugs. Patients with chronic or paroxysmal AF at high risk for stroke should be treated with long-term warfarin to achieve an international normalized ratio of 2.0-3.0. Patients with AF at low risk for stroke or with contraindications to warfarin should be treated with aspirin 325 mg daily. Management of atrial flutter is similar to management of AF. |
7,420 | Cardiac manifestations following electrocution in children. | Electrical injury can result in a variety of cardiac abnormalities. We evaluate the cardiac effects in patients injured by electric shock and treated in our medical centre.</AbstractText>We reviewed retrospectively the findings in 52 children, aged from 7 months to 17 years, with a mean age of 10.1 +/- 5.1 years, all evaluated and treated for accidental electric shock from January, 1992, through July, 2004. Relevant data regarding clinical presentation, electrocardiogram recording and cardiac enzymes was compiled. We also evaluated the echocardiographic findings, clinical course, treatment, and outcome.</AbstractText>Syncope had been the presenting symptom in 17 children (33%), asystole in 1 patient, and ventricular fibrillation or tachycardia in 2 patients. Characteristic changes of acute ischaemia of the anterior wall on the basis of changes in the ST segments were noted in 2 patients. Total creatine phosphokinase was measured in 33 children (63%), and was elevated in 20. Creatine phosphokinase-MB was measured in 11 patients, and was abnormal in six (54%). Troponin was measured in three children, and was significantly high in one (33%). Cardiopulmonary resuscitation and mechanical ventilation for a significant period was necessary in 5 patients, of whom 4 (80%) survived. None of the survivors was left with any cardiac disability following the acute event.</AbstractText>Significant cardiac damage and complications are rare in children and young adults who survive incidental electrocution. Most of the cardiac events are observed during the acute phase and immediately subsequent to electrocution. No delayed complications are anticipated.</AbstractText> |
7,421 | A simple way to decompress the left ventricle during venoarterial bypass. | The aim of this investigation was to improve the hemodynamics during venoarterial bypass by remote decompression of the left ventricle (LV).</AbstractText>Venoarterial bypass was established in 5 bovine experiments (69+/-10 kg) by the transjugular insertion of a self-expanding cannula (smartcanula) with return through a carotid artery. Cardiogenic shock was simulated with ventricular fibrillation induced by an external stimulator. Left ventricular decompression was achieved by switching to transfemoral drainage of the pulmonary artery (PA) with a long self-expanding cannula.</AbstractText>Initial pump flow was 4.7+/-0.9 l/min and the aortic pressure accounted for 75+/-21 mmHg. After induction of ventricular fibrillation, the pump flow dropped after 11+/-8 min to 2.5+/-0.1 l/min. Transfemoral decompression increased the pump flow to 5.6+/-0.7 l/min, while the RV pressure decreased from 27+/-9 to 3+/-5 mmHg, the PA pressure decreased from 29+/-7 to 5+/-4 mmHg, the LV pressure decreased from 29+/-6 to 7+/-2 mmHg, and the aortic pressure increased from 31+/-3 to 47+/-11 mmHg.</AbstractText>Remote drainage of the pulmonary artery during venoarterial bypass allows for effective decompression of the left ventricle and provides superior hemodynamics.</AbstractText> |
7,422 | Malignant idiopathic ventricular fibrillation "cured" by radiofrequency ablation. | Idiopathic Ventricular Fibrillation is a rare cause of sudden cardiac death. It may be difficult to prospectively diagnose idiopathic ventricular fibrillation due to the episodic nature of the arrhythmias as well as the inability to induce the clinical tachycardia on electrophysiological studies. Although an implantable cardioverter defibrillator can terminate episodes of ventricular fibrillation, it cannot prevent recurrences. We describe a patient who underwent radiofrequency ablation of the culprit ectopics initiating ventricular fibrillation for frequent symptomatic episodes. |
7,423 | [Amiodaron for treatment of perioperative cardiac arrythmia: a broad spectrum antiarrythmetic agent?]. | Cardiac arrhythmias are a common problem in the perioperative period. The incidence found in the current literature varies depending on the population studied and the definition of arrhythmia used. Overall supraventricular arrhythmias, namely atrial fibrillation, are the most common form. Because of its broad spectrum amiodarone is often used to suppress supraventricular and ventricular arrhythmias. It is believed to be safe for treating patients with severe cardiac disease and it has less proarrhyhmogenic potential than many other antiarrhythmic drugs. However, the use of amiodarone is limited by its cardiac and non-cardiac adverse effects, such as life-threatening bradycardia, pulmonary fibrosis or thyrotoxicosis. According to the guidelines of the American Heart Association, amiodarone can be used to treat atrial fibrillation. Because spontaneous conversion rates in the perioperative setting are high and the advantage of a rhythm control strategy over rate control is questionable, a rate control strategy using less toxic drugs like beta blockers or calcium channel blockers should be preferred in hemodynamically stable patients. The current guidelines of the European Resuscitation Council (ERC) recommend amiodarone to treat hemodynamically stable ventricular tachycardia and in this setting ajmaline is also highly effective. Amiodarone should be administered to patients with cardiac arrest if ventricular tachycardia or ventricular fibrillation persists after three attempts at defibrillation. Dronedarone is a derivate of amiodarone with a similar mechanism of action but with less non-cardiac side effects and is currently being tested in clinical trials. The use of the atrial-specific potassium channel blockers AZD7009 and vernakalant are also being investigated. Furthermore, the role of statins, ACE inhibitors and angiotensin receptor blockers in the prevention of atrial fibrillation has to be evaluated. |
7,424 | Standard basic life support vs. continuous chest compressions only in out-of-hospital cardiac arrest. | The importance of ventilations after cardiac arrest has been much debated recently and eliminating mouth-to-mouth ventilations for bystanders has been suggested as a means to increase bystander cardiopulmonary resuscitation (CPR). Standard basic life support (S-BLS) is not documented to be superior to continuous chest compressions (CCC).</AbstractText>Retrospective, observational study of all non-traumatic cardiac arrest patients older than 18 years between May 2003 and December 2006 treated by the community-run emergency medical service (EMS) in Oslo. Outcome for patients receiving S-BLS was compared with patients receiving CCC. All Utstein characteristics were registered for both patient groups as well as for patients not receiving any bystander CPR by reviewing Ambulance run sheets, Utstein forms and hospital records. Method of bystander CPR as well as dispatcher instruction was registered by first-arriving ambulance personnel.</AbstractText>Six-hundred ninety-five out of 809 cardiac arrests in our EMS were included in this study. Two-hundred eighty-one (40%) received S-CPR and 145 (21%) received CCC. There were no differences in outcome between the two patient groups, with 35 (13%) discharged with a favourable outcome for the S-BLS group and 15 (10%) in the CCC group (P=0.859). Similarly, there was no difference in survival subgroup analysis of patients presenting with initial ventricular fibrillation/ventricular tachycardia after witnessed arrest, with 32 (29%) and 10 (28%) patients discharged from hospital in the S-BLS and CCC groups, respectively (P=0.972).</AbstractText>Patients receiving CCC from bystanders did not have a worse outcome than patients receiving standard CPR, even with a tendency towards a higher distribution of known negative predictive features.</AbstractText> |
7,425 | The clinical course and risk in patients with pseudo-Mahaim fibers. | Pseudo-Mahaim (AP-M) fibers are a rare variant of atrioventricular (AV) accessory pathways. Atriofascicular and atrioventricular accessory connections are characterized by slow conduction and decremental properties. Dual physiological AV node pathways, slow and fast, are observed in a large number of patients with AP-M. Therefore, there is substrate for AV nodal reentrant tachycardia (AVNRT) in addition to antidromic AV reentrant tachycardia (AVRT) with left bundle branch block (LBBB)-like morphology. Other arrhythmia such as atrial fibrillation (AF) or atrial flutter (AFL) and ventricular fibrillation (VF) are also observed. We analysed the occurrence of arrhythmias in a group of patients with AP-M treated in our department.</AbstractText>We evaluated 27 patients (12 women) aged 14-53 years (mean age 25.6 years) with AP-M. The clinical course in these patients, in particular with regard to the occurrence of arrhythmias, was analysed. Patients with dual AV node properties were compared to patients without such findings.</AbstractText>We found dual AV node properties in 18 patients (Group 1), while 9 patients had fast pathway only (Group 2). Twenty-six patients presented with AVRT, 2 patients with AVNRT, 3 patients with AF, 1 patient with AT, 2 patients with AFL, and 3 patients with VF. In 2 patients, AP-M were seen in an atypical area. In one patient, the pathway connected the right atrium with the left ventricle (septal region), and in the other patient it connected the left atrium with the left ventricle (left anterior region).</AbstractText>The majority of AP-M was right-sided. Two thirds of patients with AP-M had anatomical substrate for AVNRT (fast/slow pathway AV node). VF or asystole occurred in 10% of patients.</AbstractText> |
7,426 | Prognostic value of Holter monitoring in congestive heart failure. | Congestive heart failure (CHF) is an increasingly widespread, costly and deadly disease, frequently named as epidemics of the 21 century. Despite advancement in modern treatment, mortality rate in CHF patients remains high. Therefore, risk stratification in patients with CHF remains one of the major challenges of contemporary cardiology. Electrocardiographic parameters based on ambulatory Holter monitoring have been documented to be independent risk predictors of total mortality and progression of heart failure. Recent years brought an increased interest in evaluation of dynamic Holter-derived ECG markers reflecting changes in heart rate and ventricular repolarization behavior. It is widely accepted that structural changes reflecting myocardial substrate are better identified by means of imaging techniques, Holter monitoring on the other hand provides complementary information on myocardial vulnerability and autonomic nervous system. Therefore, combining the electrocardiographic stratification with assessment of myocardial substrate may provide the complex insight into interplay between factors contributing to death. The present article reviews the literature data on the prognostic role of various Holter-based ECG parameters, with special emphasis to dynamic ECG risk markers--heart rate variability, heart rate turbulence, repolarization dynamics and variability--in predicting mortality, as well as different modes of death in patients with CHF. |
7,427 | Use of cardiac resynchronization therapy in patients hospitalized with heart failure. | The frequency and characterization of patients receiving cardiac resynchronization therapy (CRT) are largely unknown since the publication of pivotal clinical trials and subsequent incorporation of CRT into the American College of Cardiology/American Heart Association guidelines for heart failure.</AbstractText>We analyzed 33,898 patients admitted from January 2005 through September 2007 to 228 hospitals participating in the American Heart Association's Get With the Guidelines-Heart Failure program. There were 4201 patients (12.4%) discharged alive with CRT, including 811 new implants. Patients discharged with CRT were older (median age, 75 versus 72 years) and had lower median left ventricular ejection fraction (30% versus 38%), more frequent ischemic cardiomyopathy (58% versus 45%), more history of atrial fibrillation (38% versus 27%), and higher rates of beta-blocker and aldosterone antagonist use (P<0.0001 for all) than those without CRT. We found that 4.8% of patients with left ventricular ejection fraction <or=35% were discharged with a new CRT implant, which varied greatly by hospital. Ten percent of patients discharged with a new CRT implant had a left ventricular ejection fraction >35%. Major factors associated with lower rates of new CRT placement were treatment in the northeast (odds ratio, 0.40; 95% confidence interval, 0.30 to 0.53), black race (odds ratio, 0.45; 95% confidence interval, 0.36 to 0.57), increasing left ventricular ejection fraction per 10% (odds ratio, 0.56; 95% confidence interval, 0.52 to 0.60), and increasing age per 10 years in those >70 years of age (odds ratio, 0.56; 95% confidence interval, 0.48 to 0.65).</AbstractText>Although CRT is a recent evidence-based therapy for heart failure, patterns of use differ significantly from clinical trials and published guidelines. Important variations also exist for CRT therapy based on race, geographic region, comorbidities, and age and need to be addressed through further study and/or quality-of-care initiatives.</AbstractText> |
7,428 | Increased risk of stroke in patients with coronary artery disease and sleep apnea: a 10-year follow-up. | The effect of sleep apnea on mortality and cardiovascular morbidity is mainly unknown. We aimed to study whether sleep apnea is related to stroke, death, or myocardial infarction in patients with symptomatic coronary artery disease.</AbstractText>A total of 392 men and women with coronary artery disease referred for coronary angiography were examined by use of overnight sleep apnea recordings. Sleep apnea, defined as an apnea-hypopnea index >or=5, was recorded in 54% of the patients. All patients were followed up prospectively for 10 years, and no one was lost to follow-up. Stroke occurred in 47 (12%) of 392 patients during follow-up. Sleep apnea was associated with an increased risk of stroke, with an adjusted hazard ratio of 2.89 (95% confidence interval 1.37 to 6.09, P=0.005), independent of age, body mass index, left ventricular function, diabetes mellitus, gender, intervention, hypertension, atrial fibrillation, a previous stroke or transient ischemic attack, and smoking. Patients with an apnea-hypopnea index of 5 to 15 and patients with an apnea-hypopnea index >or=15 had a 2.44 (95% confidence interval 1.08 to 5.52) and 3.56 (95% confidence interval 1.56 to 8.16) times increased risk of stroke, respectively, than patients without sleep apnea, independent of confounders (P for trend=0.011). Death and myocardial infarction were not related to sleep apnea. Intervention in the form of coronary artery bypass grafting or percutaneous coronary intervention was related to a longer survival but did not affect the incidence of stroke.</AbstractText>Sleep apnea is significantly associated with the risk of stroke among patients with coronary artery disease who are being evaluated for coronary intervention.</AbstractText> |
7,429 | The cardiac sodium channel mutation delQKP 1507-1509 is associated with the expanding phenotypic spectrum of LQT3, conduction disorder, dilated cardiomyopathy, and high incidence of youth sudden death. | We report diverse phenotypic consequences of the delQKP-1507-1509 cardiac sodium channel mutation in three generations of a Chinese family.</AbstractText>Clinical and electrocardiographic (ECG), echocardiographic examination was followed by direct sequencing of SCN5A, KCNQ1, HERG, and LAMIN A/C to screen genomic DNA from blood samples. Of two mutation carriers, the proband was born with conduction disorders including second-degree atrioventricular (AV) block with prolonged QTc interval, additionally showing left anterior fascicular block (LAFB), incomplete right bundle-branch block (IRBBB), and intermittent third-degree AV block at 2 years, and clinical presentations of multiple syncope despite normal electroencephalograms at 8 years. Continuous ECG monitoring following presentation at 13 years revealed prolonged QTc and biphasic T-waves, multiple episodes of ventricular tachycardia, ventricular fibrillation, and torsades de pointes. Transthoracal echocardiography then revealed left ventricular dilatation and reduced systolic function. Another mutation carrier showed features of long QT syndrome type 3 (LQT3), LAFB, and dilated cardiomyopathy (DCM). Two additional subjects died suddenly at 13 and 33 years.</AbstractText>This data compliments and expands the spectrum of phenotypes resulting from this known gain-of-function mutation, including not only LQT3, cardiac conduction defects, and sudden death but also DCM, hitherto associated with loss-of-function mutations, for the first time.</AbstractText> |
7,430 | Experience of percutaneous mechanical mitral commissurotomy using metallic commissurotome in patients with mitral stenosis at chest disease institute. | Percutaneous metallic mitral commissurotomy (PMMC) has been accepted as an alternative to the traditional balloon technique. The advantage of the metallic commissurotome is that it is designed for several reuse and resterization and it is an interesting tool as seen by the authors.</AbstractText>To evaluate the efficacy and safety of PMMC among a wide range of patients with severe mitral stenosis.</AbstractText>Between July 2000 and August 2003, patients with severe mitral stenosis who underwent PMMC were enrolled Interatrial septum was punctured under transesophageal echocardiography guidance in all cases. Demographic data and baseline characteristics were collected Mitral valve area (MVA) was evaluated by echocardiography and hemodynamic parameters pre and post PMMC were compared</AbstractText>PMMC was performed in 304 patients with a broad range of severe mitral stenosis. Mean age was 38.7 +/- 10. 9 years and 79% was female. Most were in functional class 11 (94%) and 43 patients (14%) had prior commissurotomy. Atrial fibrillation was found in 41%. Twenty-six patients were crossed over to the Inoue balloon technique. The rate of success was 81% in all patients (246/304) and 89% in patients when PMMC was actually done (246/278). The MVA increased from 84 +/- 22 to 170 +/- 36 mm2 (p < 0.0001). Transvalvular gradient decreased from 17 +/- 6 to 7 +/- 4 mmHg (p < 0.0001) and mean left atrial pressure from 26 +/- 7 to 15 +/- 6 mmHg (p < 0.0001). Separation of both commissures was found in 25% and 61% had symptom relief by a reduction in functional class at least one level (p < 0.0001). Complications developed in 16 patients (5.3%) including three serious events, one death caused by severe mitral regurgitation followed by emergency surgery, another survivor after surgical repair of left ventricular free wall rupture and the last one with surgical removal of the malfunctioned device stuck in the left atrium.</AbstractText>Results of PMMC is not as encouraging as shown in previous studies. The risk of cardiac tamponade is minimized by interatrial septal puncture using transesophageal echocardiography (TEE) monitoring but this technique increased the possibility of crossover. Deterioration of the metallic commissurotome after a few procedures is demonstrated in the author's real practice.</AbstractText> |
7,431 | Postoperative oral amiodarone versus oral bisoprolol as prophylaxis against atrial fibrillation after coronary artery bypass graft surgery: a prospective randomized trial. | Postoperative atrial fibrillation (AF) occurs in up to 50% of patients undergoing coronary artery bypass (CABG) surgery and is associated with complications. Amiodarone and beta blockers are effective as prophylaxis for AF after CABG. The purpose of this study was to compare oral amiodarone versus oral bisoprolol for prevention of AF after CABG.</AbstractText>In this randomized study, 200 patients admitted for elective CABG were given oral amiodarone (n=98 patients) or oral bisoprolol (n=102 patients) beginning 6 h after surgery. Amiodarone patients received 15 mg/Kg then 7 mg/Kg/day for one month. Bisoprolol patients received 2.5 mg then 2.5 mg bid indefinitely.</AbstractText>Postoperative AF occurred in 15.3% of the patients in the amiodarone group and 12.7% of the patients in the bisoprolol group (p=0.60). Maximal ventricular rate tended to be lower in the bisoprolol group (125+/-6 beats/min) compared with the amiodarone group (144+/-7 beats/min, p=.06). Preoperative beta blockage did not affect AF incidence in either study group. There was no difference between the 2 groups for the onset time of AF episodes, total AF duration, AF recurrence and postoperative length of hospital stay. No serious postoperative complications occurred in the two study groups. Two reversible low cardiac output cases occurred with bisoprolol.</AbstractText>Postoperative oral bisoprolol and amiodarone are equally effective for prophylaxis of AF after CABG. Treatment with bisoprolol resulted in a trend to lower ventricular response rate in AF cases. Both regimens were well tolerated.</AbstractText> |
7,432 | Surgical left atrial appendage occlusion: evaluation of a novel device with magnetic resonance imaging. | Management of the left atrial appendage (LAA) is considered an important adjunct to ablation in cardiac surgical patients with atrial fibrillation (AF). However, current surgical techniques, both cut-and-sew and stapling, have been associated with incomplete LAA occlusion and complications. Using cardiac magnetic resonance imaging (MRI), we studied the safety and effectiveness of a new device for LAA occlusion in a primate model.</AbstractText>Seven adult baboons underwent off-pump placement of an LAA clip (AtriCure Inc., Westchester, Ohio). LAA occlusion was confirmed intraoperatively by direct incision. All animals had MRI before and after clip placement to assess LAA perfusion, architecture, and overall cardiac function. Pathologic and histological studies were performed at 7, 30 and 180 days.</AbstractText>Clip placement was successful in all (n=7) without any clip related complications. Complete LAA occlusion was demonstrated intraoperatively in all subjects. LAA occlusion was confirmed on pre-sacrifice MRI, and left and right ventricular function were unchanged from preoperative studies; however, clip placement caused small reductions in left ventricular end-diastolic, end-systolic, and stroke volumes. At sacrifice, direct inspection confirmed stable location, persistent LAA exclusion, tissue in-growth and homogenous epithelialization without damage to adjacent structures. Histological analysis revealed a regular in-growth pattern in all studied specimens.</AbstractText>We demonstrated a safe, straightforward, persistent and effective method for LAA occlusion with this new LAA clip. MRI effectively demonstrated LAA occlusion and only minor changes in left ventricular volumes.</AbstractText> |
7,433 | Ventricular arrhythmias in Chronic Chagas' Myocardiopathy: a case report and brief review of different antiarrhythmic strategies. | Management of ventricular arrhythmias due to Chronic Chagas' Myocardiopathy (CCM) is challenging. We present a case of CCM complicated with ventricular tachycardia (VT), and a brief review focused on VT management in this occidental emergent entity. |
7,434 | Determinants of early decline in ejection fraction after surgical correction of mitral regurgitation. | We sought to echocardiographically examine the early changes in left ventricular size and function after mitral valve repair or replacement for mitral regurgitation caused by leaflet prolapse.</AbstractText>Preoperative and early postoperative echocardiograms of 861 patients with mitral regurgitation caused by leaflet prolapse who underwent mitral valve repair or replacement (with or without coronary revascularization) were studied. Among the patients, 625 (73%) were men and 779 (90%) had mitral valve repair.</AbstractText>The rate of valve repair increased from 78% in the first decade of the study to 92% in the second decade. At early echocardiography (mean, 5 days postoperatively), we observed significant decreases in left ventricular ejection fraction (mean, -8.8) and left ventricular end-diastolic dimension (mean, -7.5). The magnitude of the early decline in ejection fraction was similar in patients who had mitral valve repair and replacement. The decrease in postoperative ejection fraction was independently associated with a lower preoperative ejection fraction, the presence of atrial fibrillation, advanced New York Heart Association functional class, greater left ventricular end-diastolic and end-systolic dimensions, and larger left atrial size.</AbstractText>Surgical correction of mitral regurgitation results in an early decrease in ejection fraction, particularly in symptomatic patients with increased left heart dimensions.</AbstractText> |
7,435 | Cell membrane stretch and chest blow-induced ventricular fibrillation: commotio cordis. | Commotio cordis, sudden cardiac death secondary to blunt nonpenetrating chest blows in sports, is reported with increasing frequency. In a swine model, ventricular fibrillation (VF) is induced by a baseball blow to the chest, and the initiation of VF is related to the peak left ventricular (LV) pressure produced by the blow. LV pressure changes likely result in cell membrane stretch and mechanical activation of ion channels. Disruption of cell cytoskeleton that anchors the cell membrane prior to precordial blows offers the opportunity to explore whether cell membrane deformation is critical to commotio cordis.</AbstractText>Twelve juvenile swine (mean 12.7 +/- 1.6 kg) were randomized to intravenous normal saline (control, n = 6) or 10 mg of intravenous colchicine (n = 6), which is known to depolymerize microtubules. Animals were given up to six blows timed to the vulnerable portion of the cardiac cycle with a 30 mph baseball on the chest directly over the cardiac silhouette. VF was initiated by 14 of the 29 (48%) impacts in the colchicine-treated animals compared with only 3 of 28 (11%) in the controls (P = 0.002). The peak generated LV pressure did not differ between colchicine animals (405 +/- 61 mmHg) and controls (387 +/- 115) (P = 0.47). However, animals administered colchicine were more likely to have VF generated by the chest blow at all pressures.</AbstractText>The initiation of VF by chest blows is significantly increased by selective disruption of the cytoskeleton, suggesting that mechanical deformation of the cell membrane is fundamental to the activation of ion channels and underlies the mechanism of VF in commotio cordis.</AbstractText> |
7,436 | QT prolongation and safety in the Indian population. | The QT interval in electrocardiogram (ECG) reflects the total duration of ventricular myocardial depolarization and repolarization. It has been well recognized that many condition may cause QT interval prolongation. Unfortunately, numbers of cardiac and non-cardiac drug prolong the QT interval and cause a distinctive polymorphic ventricular tachycardia termed torsade de pointes (TdP). TdP can degenerate into ventricular fibrillation, which leads to sudden cardiac death. Recently various regulatory and clinical bodies of Europe, USA, Canada and Australia have made their focus on the drugs that induce prolongation of QT interval. Committee for Proprietary Medicinal Products (CPMP) of the European Agency issued a document entitled 'Points to Consider: The assessment of the potential for QT interval prolongation by non-cardiovascular medicinal products' [1, 2]. In addition, USFDA adopted the guideline 'Clinical evaluation of QT/QTc interval prolongation and proarrhythmic potential for non-anti arrhythmic drugs' [3]. These documents and guidelines are primarily concern with development of novel agents and the new use or new dose of already approved drugs. The scope of this guideline is to study the effect of drugs on QT prolongation and give idea of evaluation of drug's effects on QT prolongation. Today more than 50 available drugs (both old and new) have been identify, which prolong the QT interval [1]. Several drugs have been withdrawn from many countries on this basis but many of these drugs are still available in Indian market and potentially creating life-threatening arrhythmias. This article will focus on recommendation of study on the normal limits of QT interval in Indian population and preparation of the database, which can be helpful in withdrawal of drugs from the market that produces QT prolongation. |
7,437 | [Sotalol prevents atrio-ventricular tachycardia but not atrial fibrillation with rapid ventricular response in a patient wiht WPW syndrome]. | We present a case of 23-year-old male with the Marfan syndrome multiple accessory pathways and atrio-ventricular reentry ant tachycardia (AVRT) as well as atrial fibrillation (AF). Sotalol was partially effective for AVRT, however, it did not prevent AF, RF ablation cured all arrythmias. This case shows that sotalol can attenuate AVRT recurrences, however, it does not prevent rapid conduction via accessory pathways during AF. |
7,438 | Relationship between inflammatory markers and clinical patterns of atrial fibrillation in patients with congestive heart failure. | Occurence of atrial fibrillation (AF) adversely affects left atrial size and cardiac function. This arrhythmia is also associated with an increase of plasma CRP and fibrinogen concentration. It is not clear whether elevated levels of inflammatory markers in patients with congestive heart failure (CHF) are associated with AF, clinical symptoms or adverse cardiac remodelling.</AbstractText>To investigate the association between levels of inflammatory markers and selected clinical and echocardiographic parameters as well as used treatment in the population of CHF patients with various forms of AF.</AbstractText>The cross-sectional study included 99 patients with CHF divided into 3 groups. Group I included patients with sinus rhythm. Group II consisted of patients admitted to hospital with AF and discharged with sinus rhythm (the category of paroxysmal and persistent AF). Group III comprised patients with permanent AF. In all patients plasma CRP and fibrinogen concentrations were measured and echocardiographic examination was carried out. Left atrial dimension (LA), ejection fraction (LVEF) and right ventricular systolic pressure (RVSP) were assessed.</AbstractText>Mean CRP concentration in group III (5.83+/-5.36 mg/l) was significantly higher than in group I (p=0.001) and group II (p=0.033). In the group with permanent AF mean fibrinogen concentration was elevated to a higher level (391.0+/-77.3 mg/dl) than in group II (p=0.007) and group I (p=0.099). Mean LA and RV dimensions and RVSP in group III were significantly higher than in group I and group II. Multivariable analysis revealed that plasma CRP concentration was significantly associated with the presence of arterial hypertension (p <0.001) and LA enlargement (p=0.007). A significant association between fibrinogen level and CRP level (p=0.038), presence of permanent AF (p=0.045) and metabolic syndrome (p <0.05) was found. Values of ln CRP were significantly correlated with LA diameter (r=0.24; p=0.015).</AbstractText>Increased plasma CRP level in patients with CHF were significantly associated with arterial hypertension and LA enlargement. Permanent form of AF and CRP level have been shown to be significantly associated with increased plasma fibrinogen concentration in the course of CHF.</AbstractText> |
7,439 | Atrial fibrillation down-regulates renal neutral endopeptidase expression and induces profibrotic pathways in the kidney. | Recent studies suggest that atrial fibrillation (AF) substantially influences microvascular flow in ventricular myocardium. This process may contribute to the occurrence of heart failure in AF. In general, development of heart failure and renal dysfunction go hand-in-hand causing systemic fluid overload and oedema. So far, it is unknown whether AF itself influences renal function. The aim of the present study was to determine the impact of AF on renal gene expression in a closed chest rapid atrial pacing model.</AbstractText>A total of 14 pigs were studied. In five pigs, rapid atrial pacing (AT) was performed for 7 h (600 bpm); in five additional animals, rapid atrial pacing was performed in the presence of irbesartan infusion (irbesartan group). Four pigs were instrumented without interventions (sham). After the pacing period, renal expression of collagen I alpha 1 and I alpha 3, transforming growth factor-beta (TGF-beta), neutral endopeptidase (NEP; the main enzyme involved in natriuretic protein metabolism), and atrial natriuretic peptide (ANP) were determined by RT-PCR and immunoblot analysis. Functional in vitro experiments were performed using HEK-293 kidney cells. Renal mRNA expression of NEP was substantially down-regulated during AT (AT: 12.7 +/- 9.3% vs. sham: 100 +/- 43.4%; P < 0.01). Results at the mRNA level were confirmed at the protein level. Irbesartan therapy did not prevent down-regulation of NEP. In contrast, TGF-beta1 mRNA expression was up-regulated (AT: 208.5 +/- 79.3% vs. sham: 100 +/- 34.6% P< 0.05). Collagen and angiotensin II type 1 receptor (AT1R) expression were not significantly altered by AT. HEK-293 cells were used to determine the potential humoral factors involved in down-regulation of NEP. Application of aldosterone, ANP, asymmetric dimethylarginine, and angiotensin peptides failed to cause down-regulation of renal NEP expression in vitro.</AbstractText>AT reduces NEP expression and stimulates TGF-beta1 signalling in the kidneys. Thus, even brief episodes of AT affect renal gene expression, which may account for structural renal changes and alterations of renal function in the long term.</AbstractText> |
7,440 | Optimal transvenous coil position on active-can single-coil ICD defibrillation efficacy: a simulation study. | The implantable cardioverter defibrillator with an active can and a single coil lead is effective in treating ventricular fibrillation, but the lead placement associated with the high defibrillation efficacy is still controversial and remains largely empirical. In this study, an anatomically realistic finite difference model of the thorax was developed based on MRI cross-sectional images of a human thorax to examine the effect of transvenous coil placement on defibrillation efficacy. Four electrode configurations with the coil was placed, respectively, in the right ventricular (RV) apex, in the middle of RV cavity, along the free wall in RV, or along the septal wall in RV, were simulated and their defibrillation efficacies were evaluated based on a set of metrics including voltage defibrillation threshold, current defibrillation threshold, interelectrode impedance, potential gradient distribution uniformity, current density distribution, and myocardium damage. It was found that the optimal electrode configuration is to position the coil in the middle of the RV cavity. The results were compared with the results from a simplified thoracic model. The comparison indicates that for a given electrode configuration a simplified representation of the thorax may overestimate defibrillation efficacy. |
7,441 | Long-term predictors of mortality in ICD patients with non-ischaemic cardiac disease: impact of renal function. | Randomized trials have demonstrated that implantable cardioverter defibrillator (ICD) therapy may reduce the risk of death in patients with non-ischaemic cardiomyopathy (CMP). In this study, we aimed at determining the long-term benefit of ICD therapy among patients with dilated CMP (DCM) and among those with other non-ischaemic cardiac diseases (NICDs).</AbstractText>We performed a single-centre longitudinal study to assess the outcomes of 176 patients with NICDs who were implanted with an ICD for primary or secondary prevention of cardiac death. The cumulative survival rate after 1, 2, 5, and 10 years was 91, 87, 78, and 65%, respectively. Mortality risk did not differ significantly between patients with DCM and those with other NICDs. Atrial fibrillation, recurrent ventricular arrhythmias requiring ICD therapy, and right ventricular pacing, but not delayed intrinsic ventricular conduction, were associated with higher risk. New York Heart Association (NYHA) functional class > or =III was an independent predictor of adverse outcome among patients with DCM [hazard ratio (HR) 5.27, P = 0.01], whereas reduced left ventricular function with ejection fraction <35% (HR 12.1, P < 0.001) and anti-arrhythmic drug use (HR 4.82, P = 0.03) were independent predictors among those with other NICDs. Renal insufficiency with estimated glomerular filtration rate <60 mL/min/1.73 m(2) (HR 5.9, P < 0.001) was a strong independent predictor of mortality among all patients with NICD, irrespective of underlying cardiac condition.</AbstractText>In ICD patients with DCM, higher NYHA functional class is associated with adverse outcomes. Impaired left ventricular function and anti-arrhythmic drug use predict higher mortality among patients with non-dilated, NICDs. Impaired renal function is a strong predictor of mortality in all patients with NICD.</AbstractText> |
7,442 | Ventricular fibrillation in King County, Washington: a 30-year perspective. | We determined the effect of four major program changes over a 30-year period on survival from witnessed cardiac arrest (CA) with ventricular fibrillation (VF) as the rhythm causing collapse.</AbstractText>We conducted an investigation of emergency medical services (EMS)-treated CA occurring between 1978 and 2007. Data were obtained from a registry maintained by the King County Emergency Medical Services Division. Using Utstein style definitions, we measured changes in patient survival in light of four programs that were implemented during the span of the study: defibrillation by emergency medical technicians (EMTs), dispatcher-assisted cardiopulmonary resuscitation (CPR), public access defibrillation, and a CPR-defibrillation protocol that replaced delivery of three sequential shocks with administration of one shock followed by 2 min of CPR.</AbstractText>Overall survival from witnessed VF during the study period was 34%. While demographic characteristics of patients in CA remained constant, we observed greater rates of survival in the years following the program changes, 1983-2006, compared to survival in the period before the changes, 1977-1982. The greatest increase in survival occurred following the CPR-defibrillation protocol change in 2005.</AbstractText>Despite adverse temporal trends, the four program changes appear to have contributed to increasing survival rates from out-of-hospital cardiac arrests in King County.</AbstractText> |
7,443 | No benefit from defibrillation threshold testing in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial). | This study investigated whether defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator (ICD) implantation predicts clinical outcomes.</AbstractText>Defibrillation testing is often performed during insertion of ICDs to confirm shock efficacy. There are no prospective data to suggest that this procedure improves outcomes when modern ICDs are implanted for primary prevention of sudden death.</AbstractText>The analysis included the 811 patients who were randomized to the ICD arm of the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) and had the device implanted. The DFT testing protocol in SCD-HeFT was designed to limit shock testing in a primary prevention heart failure population.</AbstractText>Baseline DFT data were available for 717 patients (88.4%). All 717 patients had a DFT of < or =30 J, the maximum output of the device in this study. The DFT was < or =20 J in 97.8% of patients. There was no survival difference between patients with a lower DFT (< or =10 J, n = 547) and a higher DFT (>10 J, n = 170) (p = 0.41). First shock efficacy was 83.0% for the first clinical ventricular tachyarrhythmia event; there were no differences in shock efficacies when the cohort was subdivided by baseline DFT.</AbstractText>Low baseline DFTs were obtained in patients with stable, optimally treated heart failure during ICD implantation for primary prevention of sudden death. First shock efficacy for ventricular tachyarrhythmias was high regardless of baseline DFT testing results. Baseline DFT testing did not predict long-term mortality or shock efficacy in this study.</AbstractText> |
7,444 | Strategic programming of detection and therapy parameters in implantable cardioverter-defibrillators reduces shocks in primary prevention patients: results from the PREPARE (Primary Prevention Parameters Evaluation) study. | Our purpose was to demonstrate that strategically chosen implantable cardioverter-defibrillator (ICD) ventricular tachycardia (VT) or ventricular fibrillation (VF) detection and therapy parameters can reduce the combined incidence of device-delivered shocks, arrhythmic syncope, and untreated sustained symptomatic VT/VF (morbidity index).</AbstractText>Strategically chosen ICD VT/VF detection and therapy parameters have been shown in previous studies to reduce the number of shocked episodes. In the PREPARE (Primary Prevention Parameters Evaluation) study, these prior strategies were combined with additional strategies specific to primary prevention patients.</AbstractText>The PREPARE study was a prospective, cohort-controlled study that analyzed 700 patients (biventricular [Bi-V] ICD and non-Bi-V ICD) with primary prevention indications for an ICD from 38 centers followed for 1 year. VT/VF was detected for rates > or =182 beats/min that were maintained for at least 30 of 40 beats. Antitachycardia pacing was programmed as the first therapy for regular rhythms with rates of 182 to 250 beats/min, and supraventricular tachycardia discriminators were used for rhythms < or =200 beats/min. The control cohort consisted of 689 primary prevention patients from the EMPIRIC (Comparison of Empiric to Physician-Tailored Programming of Implantable Cardioverter Defibrillators Trial) (non-Bi-V ICD, physician arm only) and MIRACLE ICD (Multicenter InSync Implantable Cardioversion Defibrillation Randomized Clinical Evaluation) (Bi-V ICD) trials for whom VT/VF detection and therapy programming were not controlled.</AbstractText>The PREPARE programming significantly reduced the morbidity index incidence density (0.26 events/patient-year for PREPARE study patients vs. 0.69 control cohort, p = 0.003). The PREPARE study patients were less likely to receive a shock in the first year compared with control patients (9% vs. 17%, p < 0.01). The incidence of untreated VT and arrhythmic syncope was similar between the PREPARE study patients and the control cohort.</AbstractText>Strategically chosen VT/VF detection and therapy parameters can safely reduce shocks and other morbidities associated with ICD therapy in patients receiving an ICD for primary prevention indications. (PREPARE-Primary Prevention Parameters Evaluation; NCT00279279).</AbstractText> |
7,445 | [The impact of quality of cardiopulmonary resuscitation on post-resuscitation inflammatory reaction in a porcine cardiac arrest model]. | To evaluate the effects of quality of non-standard cardiopulmonary resuscitation (N-CPR) and new guidelines recommended standard CPR (S-CPR) on post-resuscitation inflammatory reaction in a cardiac arrest (CA) porcine model.</AbstractText>Eighteen pigs were randomly divided into two groups, and ventricular fibrillation (VF) was induced by programmed electrical stimulation after giving anesthesia, intubation tube and mechanical ventilation. S-CPR (n=9): CPR was consistent with recommendation of the 2005 guidelines. N-CPR (n=9): given CPR with low quality CPR usually instituted in clinic. After 4 minutes of untreated VF, CPR was started for 9 minutes. Defibrillation and advanced life support were attempted at 13 minutes of CA. All resuscitated animals were supported with intensive care equipment for 4 hours, and then experimental indexes were observed. Animals were sacrificed if they survived for 24 hours, and tissues of cerebral cortex, cardiac muscle, kidney, and liver were harvested for immunohistochemistry to evaluate the expression of nuclear factor-KappaB (NF-KappaB). The changes in hemodynamics was measured at CPR 3, 6, and 9 minutes, and the serum levels of tumor necrosis factor (TNF-alpha), interleukin-1 beta (IL-1 beta) were determined before CA, CPR 9 minutes, and 4 hours after restoration of spontaneous circulation (ROSC).</AbstractText>Compared with N-CPR, S-CPR resulted in a significantly higher ROSC (22.2% vs. 88.9%) and 24-hour survival rate (22.2% vs. 88.9%, both P<0.05), and significant improved cardiac output (CO) and mean arterial pressure (MAP) at CPR 3, 6, 9 minutes (all P<0.01) . S-CPR also yielded lower serum values of TNF-alpha, IL-1 beta and lower expression of NF-KappaB at CPR 9 minutes and ROSC 4 hours.</AbstractText>High quality CPR not only improves survival of CA pigs, but also alleviates post-resuscitation inflammatory reaction.</AbstractText> |
7,446 | Downregulated FKBP12.6 expression and upregulated endothelin signaling contribute to elevated diastolic calcium and arrhythmogenesis in rat cardiomyopathy produced by l-thyroxin. | Dissociation of FKBP12.6 from RyR2 is considered as an important molecular event resulting in calcium leak and an increased risk in arrhythmogenesis. We hypothesized that augmented ventricular fibrillation (VF) on reperfusion of rat cardiomyopathy induced by l-thyroxin may result from elevated diastolic Ca(2+) levels due to dissociation (downregulation) of FKBP12.6 and upregulation of endothelin (ET-1) signaling pathway.</AbstractText>Rats were treated with l-thyroxin (0.4 mg/kg, s.c.) for 10 days. Dajisentan (CPU0213), a dual endothelin receptor antagonist (100 mg/kg p.o.), or propranolol was administered on day 6 to 10. Susceptibility to VF was evaluated on ischemia/reperfusion episode. mRNA expression of FKBP12.6, and ET-1 levels were determined. Calcium transients and FKBP12.6 immunohistochemistry were measured by confocal microscopy in isolated cardiomyocytes from cardiomyopathy.</AbstractText>Cardiomyopathy induced by l-thyroxin resulted in an increased susceptibility to VF on ischemia/reperfusion. Upregulated mRNA expression of RyR2 and PKA in association with downregulated FKBP12.6 expression was found in l-thyroxin-treated rats compared to controls. Calcium transients evoked by field electrical stimulation showed an increase in Ca(2+) by +75% during diastole. An increase in ET-1 (ng/mg protein) (+36.6%) and mRNA abundance of preproET-1 were found in the left ventricle. A decreased mRNA ratio of FKBP12.6 to RyR2 likely reflected dissociation of FKBP12.6 in cardiomyopathy. These changes were normalized by Dajisentan, comparable to propranolol.</AbstractText>Increased susceptibility to VF in l-thyroxin-induced cardiomyopathy is related to increase in diastolic Ca(2+) levels, resulting from downregulated FKBP12.6 and upregulated ET system. ET antagonism might be useful in settings of FKBP12.6 dissociation.</AbstractText> |
7,447 | Electrocardiographic features in a patient with the coexistence of long QT syndrome and coronary vasospasm. | A 20-year-old woman suffered from cardiopulmonary arrest due to ventricular fibrillation. The electrocardiogram after resuscitation showed prolonged QTc interval with bifid T wave. On the third hospital day, the QTc interval and the T-wave changes improved. However, the QTc interval was distinctively prolonged after administration of epinephrine, oral glucose load, and intracoronary acetylcholine (Ach) into the left coronary artery. Moreover, an injection of Ach into the right coronary artery provoked severe coronary spasm. This is a case of the coexistence of long QT syndrome (LQTS) and coronary vasospasm, which may give an important clinical implication for the treatment of LQTS. |
7,448 | Lack of diurnal variation of P-wave and QT dispersions in patients with heart failure. | P-wave dispersion (PWD) is a new parameter for the assessment of risk of atrial fibrillation and has been reported to be increased in heart failure. Diurnal variation of the PWD has been reported in patients with coronary artery disease (CAD). QT dispersion (QTD) has also a circadian variation. In this study we aimed to search diurnal variation of PWD and QTD in patients with heart failure.</AbstractText>Fifty-three clinical heart failure patients having left ventricular ejection fraction (LVEF) <40% were divided into two groups according to presence of CAD. Twelve-lead ECGs were obtained in the morning (07:00-08:00 hours), at noon (12:00-14:00 hours), and at night (22:00-24:00 hours).</AbstractText>All the patients were in New York Heart Association class II except one in class I. beta-blocker and angiotensin-converting enzyme inhibitor or angiotensin receptor blocker usage was over 80% and spiranolactone usage was around 75% in the study group. PWD and QTD were not significantly different between patients with (n = 27) and without (n = 26) CAD. There was no significant diurnal variation of P wave and QT parameters.</AbstractText>We found that PWD and QTD do not show diurnal variation in patients having either ischemic or nonischemic origin of heart failure treated with optimal drug therapy.</AbstractText> |
7,449 | Effects of continuous and triggered atrial overdrive pacing on paroxysmal atrial fibrillation in pacemaker patients. | The aim of the study was to compare the effects of different pacing strategies to prevent paroxysmal atrial fibrillation (AF): triggered atrial overdrive pacing versus the combination of triggered and continuous overdrive pacing.</AbstractText>Patients with an indication for dual-chamber pacing (Selection 9000, Prevent AF; Vitatron B.V., Arnhem, the Netherlands) and a history of paroxysmal AF were randomized to triggered atrial pacing (three pacing functions, "triggered group": PAC Suppression, Post-PAC Response, and Post-Exercise Response) or to the combination of continuous (Pace Conditioning) and triggered atrial pacing (four pacing functions, "combined group"). After 3 months, there was a crossover to the other pacemaker setting.</AbstractText>In 171 enrolled patients, the median AF burden of the combined group was with 2.1% versus 0.1% in the triggered group (P = 0.014). Fewer AF episodes were observed in the triggered (median: 7) than in the combined group (median: 116; P = 0.016). The combined group had more frequent atrial pacing (median 97%) than the triggered group with 85% (P < 0.001), but ventricular pacing was not significantly different with 95% and 96% in the combined and triggered group, respectively. After the crossover, the AF burden increased in the triggered group to 0.3% and decreased in the combined group to 0.4%.</AbstractText>Triggered atrial pacing functions alone resulted in a low AF burden. The additional activation of continuous atrial overdrive pacing increased the percentage of atrial pacing, but had no beneficial effects on the prevention of paroxysmal AF.</AbstractText> |
7,450 | Malignant arrhythmia in apical ballooning syndrome: risk factors and outcomes. | We sought to determine the frequency and outcomes with symptomatic arrhythmia in patients with apical ballooning syndrome (ABS).</AbstractText>A retrospective review of the Mayo Clinic Angiography database was conducted to identify patients who met the Mayo criteria for ABS. Patients with documented arrhythmias formed the study group, and 31 randomly selected patients with ABS but without arrhythmia formed the control group.</AbstractText>Out of 105 patients identified with ABS, 6 (5.7%) women aged 69 +/- 9 years experienced significant arrhythmia (ventricular fibrillation, asystole), 2 patients died, and 1 required permanent pacemaker implantation. When compared with controls, the study group showed no significant difference with respect to ECG characteristics (QT, QRS duration or axis) except for R-R interval variability (see comments below) (30.6+/-6 vs 14.5+/-17 p = 0.0004), QTc, and P-R interval. Patients without arrhythmia were more likely to be on beta-blocker therapy than the study population (33% vs 80.6% p = 0.02).</AbstractText>Life-threatening arrhythmia is uncommon (5.7%) with ABS despite marked, structural abnormalities. When arrhythmias do occur, the outcome is poor. Prominent variability in R-R intervals appears to be predictive of significant arrhythmias in ABS. The role of beta-blocker therapy in preventing arrhythmia with ABS requires further investigation.</AbstractText> |
7,451 | Troponin elevation in patients with various tachycardias and normal epicardial coronaries. | Troponin elevation is usually synonymous with acute coronary syndrome (ACS). Although sensitive for ACS, the elevation of serum troponin, in the absence of clinical evidence of ischemia, should prompt a search for other etiologies of myocardial necrosis. In fact, elevated values of troponin are correlated with myocardial necrosis even though it does not discriminate the mechanism involved. We report a series of seven patients (age range 18-67 years), who presented with complaints of chest discomfort and were found to have regular supraventricular tachycardia (5 patients) and one patient each with atrial fibrillation and ventricular tachycardia. All these patients had elevated troponin I and underwent coronary angiography that revealed normal epicardial coronary arteries. This is first case series in which all patients underwent coronary angiography and none of the patients was hemodynamically unstable at the time of presentation. Patients with elevated troponin due to conditions other than ACS can receive inappropriate and delayed definitive diagnosis and treatment. |
7,452 | Nitric oxide inhibits Kv4.3 and human cardiac transient outward potassium current (Ito1). | Chronic atrial fibrillation (CAF) is characterized by a shortening of the plateau phase of the action potentials (AP) and a decrease in the bioavailability of nitric oxide (NO). In this study, we analysed the effects of NO on Kv4.3 (I(Kv4.3)) and on human transient outward K(+) (I(to1)) currents as well as the signalling pathways responsible for them. We also analysed the expression of NO synthase 3 (NOS3) in patients with CAF.</AbstractText>I(Kv4.3) and I(to1) currents were recorded in Chinese hamster ovary cells and in human atrial and mouse ventricular dissociated myocytes using the whole-cell patch clamp. The expression of NOS3 was analysed by western blotting. AP were recorded using conventional microelectrode techniques in mouse atrial preparations. NO and NO donors inhibited I(Kv4.3) and human I(to1) in a concentration- and voltage-dependent manner (IC(50) for NO: 375.0 +/- 48 nM) as a consequence of the activation of adenylate cyclase and the subsequent activation of the cAMP-dependent protein kinase and the serine-threonine phosphatase 2A. The density of the I(to1) recorded in ventricular myocytes from wild-type (WT) and NOS3-deficient mice (NOS3(-/-)) was not significantly different. Furthermore, the duration of atrial AP repolarization in WT and NOS3(-/-) mice was not different. The increase in NO levels to 200 nM prolonged the plateau phase of the mouse atrial AP and lengthened the AP duration measured at 20 and 50% of repolarization of the human atrial CAF-remodelled AP as determined using a mathematical model. However, the expression of NOS3 was not modified in left atrial appendages from CAF patients.</AbstractText>Our results suggested that the increase in the atrial NO bioavailability could partially restore the duration of the plateau phase of CAF-remodelled AP by inhibiting the I(to1) as a result of the activation of non-canonical enzymatic pathways.</AbstractText> |
7,453 | Subsequent ventricular fibrillation and survival in out-of-hospital cardiac arrests presenting with PEA or asystole. | The prognostic implications of conversion to ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OHCA) patients with an initial non-shockable rhythm are unclear.</AbstractText>Among OHCA patients with an initial non-shockable rhythm, survival is better in individuals who subsequently develop VF and are defibrillated.</AbstractText>Utstein style population-based cohort study.</AbstractText>adults (age>or=18 years) with OHCA of presumed cardiac etiology and initial rhythm of pulseless electrical activity (PEA) or asystole treated by emergency medical services systems in Osaka, Japan from January 1, 2001 to December 31, 2005. Primary outcome measure was one-month neurologically favorable survival (CPC<or=2). Outcome of patients with subsequent VF (SHOCK group) was compared to that of patients with sustained non-shockable rhythm (NON-SHOCK group) using logistic regression to adjust for potential confounding variables.</AbstractText>Of 14,316 OHCA, 12,353 cases had PEA or asystole as the initial rhythm. Of these, 11,766 (95%) remained in a non-shockable rhythm throughout the resuscitation effort while 587 (5%) subsequently developed VF and were defibrillated. Neurologically favorable survival at one month was significantly better in the SHOCK group (6% versus 1%, p<0.001). Subsequent VF remained a significant predictor (OR, 4.3; 95% CI, 2.8-6.7) of neurologically favorable survival after adjustment for potential confounders.</AbstractText>Based on a large-scaled population-based cohort of OHCA, subsequent VF with defibrillation was associated with better outcomes among patients with an initial non-shockable rhythm.</AbstractText> |
7,454 | Comparison of benefits and mortality in cardiac resynchronization therapy in patients with atrial fibrillation versus patients in sinus rhythm (Results of the Spanish Atrial Fibrillation and Resynchronization [SPARE] Study). | The efficacy of cardiac resynchronization therapy (CRT) in patients with atrial fibrillation (AF) and the need for atrioventricular junction ablation in these patients is controversial. The aim of the study was to analyze CRT results in patients with permanent AF. A total of 470 consecutive patients who underwent CRT in 6 centers were included in this study. Of these patients, 126 (27%) had permanent AF. Patients were evaluated at baseline and 12 months. No difference was found in the magnitude of improvement experienced by patients with AF compared with those in sinus rhythm (SR) with respect to quality of life, distance in 6-minute walking test, and left ventricular reverse remodeling. Despite the beneficial effects of CRT, death from refractory heart failure at 12 months was higher in patients with AF (17 of 126; 13.5%) than those in SR (14/344; 4.1%; p <0,001). Furthermore, permanent AF was an independent predictive factor for mortality from refractory heart failure (hazard ratio 5.4, 95% confidence interval 1.9 to 15.1). In conclusion, patients with AF treated with CRT who survived at the 12-month follow-up had the same functional improvement and remodeling as those in SR. However, AF was an independent risk factor for mortality from heart failure after CRT implantation. |
7,455 | [Prophylactic use of cardiac implantable defibrillators in patients with severe left ventricular dysfunction: how to deal with decision making among guidelines, clinical practice, ethical problems, and limited economic resources]. | Sudden cardiac death (SCD) is usually due to ventricular tachycardia/fibrillation and represents one of the most important medical and socio-economical problems in western countries. It accounts for approximately 1 life/1000 subjects/year. New and effective treatments are necessary to reduce such dramatic event. During the last decade implantable cardioverter-defibrillators (ICDs) showed to be an effective tool to reduce both total and SCD mortality either when used for secondary or primary SCD prevention. At present, ICD implantation guidelines suggest to implant an ICD in all the patients on the basis of a left ventricular ejection fraction < or =30-35% only. This scarcely sensitive and specific criterion implies the necessity to implant very costly devices in a wide number of patients to save only few lives. A more accurate patient selection is desirable either from a clinical or ethical or economic point of view. Fortunately, this appears to be possible using well known and proven epidemiological, clinical and risk stratification data. On the basis of such data, more selective ICD implantation criteria might be used in older patients or in patients with significant comorbidity or in those patients identified at very low risk of SCD. |
7,456 | [Effects of pretreatment with amiodarone infusion in patients with persistent atrial fibrillation submitted to external electrical cardioversion: a single center experience]. | Several studies demonstrated the efficacy of amiodarone pretreatment in achieving bet-ter outcomes after electrical cardioversion of atrial fibrillation. In the majority of cases, oral amiodarone for at least 1 month was administered, with the result of lengthening of pre-cardioversion time. Only one study in the literature reported high-dose amiodarone infusion, showing an increase in the incidence of slow arrhythmias. The aim of this study was to test the efficacy of pretreatment infusion of a single dose of amiodarone few hours before electrical cardioversion in restoring sinus rhythm and reducing the incidence of early arrhythmic recurrences.</AbstractText>The study was retrospective. We analyzed a population of 155 patients with persistent atrial fibrillation, from May 2003 to November 2005. The first group of 86 patients was treated with amiodarone at the dose of 4 mg/kg in 30 min, few hours before electrical cardioversion; the second group of 69 patients was treated with electrical cardioversion without pharmacological pretreatment. The two groups were homogeneous for age, sex, coronary artery disease, duration of arrhythmia, atrial dimensions, left ventricular ejection fraction, and paddle position for electrical cardioversion.</AbstractText>There were no significant differences between the two groups in terms of efficacy of cardioversion (95.3 vs 91.3%, p = NS). Pretreatment with bolus of amiodarone significantly reduced the incidence of immediate recurrence (3.5 vs 17.4%, p < 0.05) and the mix of immediate and early recurrence (19.7 vs 33.3%, p < 0.05). There were no significant differences in the incidence of late recurrences (17.4 vs 13%, p = NS). There were no significant bradyarrhythmias in the two groups. Amiodarone pretreatment did not reduce energy delivery to obtain cardioversion.</AbstractText>Amiodarone pretreatment with intravenous bolus few hours before electrical cardioversion reduces short-term recurrences of atrial fibrillation. It does not reduce energy delivery of electrical cardioversion and does not increase the incidence of slow arrhythmias. Randomized prospective studies are warranted to confirm these findings.</AbstractText> |
7,457 | Virtual electrodes and the induction of fibrillation in Langendorff-perfused rabbit ventricles: the role of intracellular calcium. | A strong premature electrical stimulus (S(2)) induces both virtual anodes and virtual cathodes. The effects of virtual electrodes on intracellular Ca(2+) concentration ([Ca(2+)](i)) transients and ventricular fibrillation thresholds (VFTs) are unclear. We studied 16 isolated, Langendorff-perfused rabbit hearts with simultaneous voltage and [Ca(2+)](i) optical mapping and for vulnerable window determination. After baseline pacing (S(1)), a monophasic (10 ms anodal or cathodal) or biphasic (5 ms-5 ms) S(2) was applied to the left ventricular epicardium. Virtual electrode polarizations and [Ca(2+)](i) varied depending on the S(2) polarity. Relative to the level of [Ca(2+)](i) during the S(1) beat, the [Ca(2+)](i) level 40 ms after the onset of monophasic S(2) increased by 36+/-8% at virtual anodes and 20+/-5% at virtual cathodes (P<0.01), compared with 25+/-5% at both virtual cathode-anode and anode-cathode sites for biphasic S(2). The VFT was significantly higher and the vulnerable window significantly narrower for biphasic S(2) than for either anodal or cathodal S(2) (n=7, P<0.01). Treatment with thapsigargin and ryanodine (n=6) significantly prolonged the action potential duration compared with control (255+/-22 vs. 189+/-6 ms, P<0.05) and eliminated the difference in VFT between monophasic and biphasic S(2), although VFT was lower for both cases. We conclude that virtual anodes caused a greater increase in [Ca(2+)](i) than virtual cathodes. Monophasic S(2) is associated with lower VFT than biphasic S(2), but this difference was eliminated by the inhibition of the sarcoplasmic reticulum function and the prolongation of the action potential duration. However, the inhibition of the sarcoplasmic reticulum function also reduced VFT, indicating that the [Ca(2+)](i) dynamics modulate, but are not essential, to ventricular vulnerability. |
7,458 | Inducibility of atrial fibrillation during electrophysiologic evaluation is associated with increased dispersion of atrial refractoriness. | The impact of atrial dispersion of refractoriness (Disp_A) in the inducibility and maintenance of atrial fibrillation (AF) has not been fully resolved.</AbstractText>To study the Disp_A and the vulnerability (A_Vuln) for the induction of self-limited (<60 s) and sustained episodes of AF.</AbstractText>Forty-seven patients with paroxysmal AF (PAF): 29 patients without structural heart disease and 18 with hypertensive heart disease. Atrial effective refractory period (ERP) was assessed at five sites--right atrial appendage and low lateral right atrium, high interatrial septum, proximal and distal coronary sinus. We compared three groups: group A - AF not inducible (n=13); group B - AF inducible, self-limited (n=18); group C - AF inducible, sustained (n=16). Age, lone AF, hypertension, left atrial and left ventricular (LV) dimensions, LV systolic function, duration of AF history, atrial flutter/tachycardia, previous antiarrhythmics, and Disp_A were analysed with logistic regression to determine association with A_Vuln for AF inducibility. The ERP at different sites showed no differences among the groups. Group A had a lower Disp_A compared to group B (47+/-20 ms vs 82+/-65 ms; p=0.002), and when compared to group C (47+/-20 ms vs 80+/-55 ms; p=0.008). There was no significant difference in Disp_A between groups B and C. By means of multivariate regression analysis, the only predictor of A_Vuln was Disp_A (p=0.04).</AbstractText>In patients with PAF, increased Disp_A represents an electrophysiological marker of A_Vuln. Inducibility of both self-limited and sustained episodes of AF is associated with similar values of Disp_A. These findings suggest that the maintenance of AF is influenced by additional factors.</AbstractText> |
7,459 | QT prolongation is an unreliable predictor of ventricular arrhythmia. | Not all drugs that prolong the QT interval are proarrhythmic, and absence of QT prolongation is no guarantee for lack of proarrhythmia. Thus, QT prolongation is an unreliable predictor of ventricular arrhythmia. Development of drugs based on the absence of QT prolongation may stop development of some of the safest agents (with respect to arrhythmias). Conversely, drug-induced shortening of the QT interval may facilitate reentry, which might have lethal consequences in vulnerable patients. If QT prolongation and QT shortening must be avoided, then the pharmaceutical industry faces a mission impossible. Cardiac safety is better evaluated in terms of lambda, TRIaD (Triangulation, Reverse use dependence, Instability, and Dispersion), and disturbances of automaticity. |
7,460 | Transmural dispersion of refractoriness and conduction velocity is associated with heterogeneously reduced connexin43 in a rabbit model of heart failure. | Heterogeneity of repolarization and conduction is a potential source of arrhythmogenesis. In heart failure (HF), intercellular coupling is reduced and heterogeneities may become evident because of reduced intercellular coupling.</AbstractText>This study sought to investigate connexin43 (Cx43) expression, conduction velocity (CV), refractoriness and inducibility of arrhythmias at multiple sites of the left ventricle during HF.</AbstractText>HF was induced by pressure-volume overload in rabbits. Epicardial and intramural mapping was performed in isolated perfused hearts following programmed stimulation. Myocytes were enzymatically dissociated and studied using D-4-ANEPPS fluorescence. Western blotting and immunohistochemistry was performed to quantify heterogeneity of Cx43 expression.</AbstractText>Cx43 was heterogeneously reduced in the midmyocardial, but not in the sub epicardium layer of the left ventricular free wall in HF compared to control rabbits. In HF, subepicardial and midmyocardial refractory periods (RPs) were increased compared to control rabbits (148 +/- 3 ms and 143 +/- 3 versus 131 +/- 2 and 129 +/- 2 ms, respectively, both P < 0.001). Also, transmural dispersion of RPs was larger in HF (30 +/- 4 ms) than in control rabbits (24 +/- 3 ms, P < 0.05). Intrinsic dispersion of action potential duration in isolated myocytes was similar in HF and control rabbits. Transmural CV was heterogeneous, although the mean CV was not different between groups. Arrhythmias were more easily inducible in HF, especially from midmyocardium.</AbstractText>In HF, midmyocardial Cx43 expression is heterogeneously reduced. This is associated with increased transmural dispersion in refractoriness and conduction, and with increased arrhythmia inducibility.</AbstractText> |
7,461 | Feasibility of endoscopic guidance for nonsurgical transthoracic atrial and ventricular epicardial ablation. | Epicardial catheter ablation via subxiphoid percutaneous access currently is used upon failure of endocardial catheter ablation. The safety, efficacy, and applicability of epicardial catheter ablation likely will improve with direct visualization of the pericardial space.</AbstractText>The purpose of this study was to assess the feasibility of percutaneous endoscopic guidance for identification of epicardial anatomic landmarks and epicardial catheter ablation.</AbstractText>Dual subxiphoid epicardial access and femoral venous and arterial access were obtained in six healthy swine. The endoscope and electrophysiology catheter were advanced to the pericardial space. Anatomic landmarks were identified via endoscopy and confirmed by multiview fluoroscopic assessment of proximity to endocardial catheters in the area of interest. Radiofrequency ablation of selected anatomic targets was performed under endoscopic guidance. Targeting of lesions was assessed by pathologic examination of the target and surrounding structures.</AbstractText>Dual large-bore subxiphoid epicardial access was obtained without complications in all animals. The coronary sinus, left anterior descending coronary artery, left atrial appendage, and pulmonary veins were easily visualized in all animals. Catheter ablation of anatomic targets, including the right ventricular outflow tract, left atrial appendage, and pulmonary veins, was performed successfully under direct endoscopic observation. Endoscopic guidance of point and linear lesions near coronary vessels also was assessed. Pathology revealed successful targeting of lesions.</AbstractText>Endoscopic guidance of percutaneous epicardial electrophysiologic procedures is feasible. Direct visualization of epicardial structures, catheters, and lesions may improve the safety and efficacy of epicardial catheter ablation and reduce staff and patient radiation exposure.</AbstractText> |
7,462 | Future directions in cardiocerebral resuscitation. | Outcomes from pediatric cardiac arrest and cardiopulmonary resuscitation (CPR) seem to be incrementally improving. The past 2 decades have brought advances in the understanding of the pathophysiology of cardiac arrest and ventricular fibrillation, better treatment strategies, and a more robust standard for CPR epidemiology and research reporting. The evolution of practice based on an improved understanding of the pathophysiology and timing, intensity, duration, and variability of the hypoxic-ischemic insult should lead to goal-directed therapy gated to the phase of cardiac arrest and the postarrest period encountered. By strategically focusing therapies to specific phases of cardiac arrest and resuscitation and to the evolving pathophysiology and by implementing evidence-based practice, there is great promise that critical care interventions can lead the way to more successful cardiopulmonary and cerebral resuscitation in children. |
7,463 | Clinical importance of short-long-short sequences: analysing the mode of onset of ventricular tachycardias and atrial fibrillation. | Clinical importance of atrial and ventricular ectopic beats are investigated in some experimental and clinical trials. They are common and occur in a broad spectrum of the population. This includes patients without structural heart disease and those with any form of cardiac disease, independent of severity. Although we know something about the mechanisms and etiology of serious ventricular arrhythmias and atrial fibrillation, we don't know a lot about mode of onset of those arrhythmias. Can short-long-short sequences, related ectopic beats predict AF and ventricular tachycardias in some selected groups of patients? In this paper we will try to answer this important question. |
7,464 | A focus on when and when not to use antiarrhythmic drugs in treating ventricular arrhythmias and indications for the use of automatic implantable cardioverter-defibrillators. | Underlying causes of ventricular tachycardia (VT) or complex ventricular arrhythmias (VA) should be treated if possible. Antiarrhythmic drugs should not be used to treat asymptomatic persons with complex VA and no heart disease. Beta blockers are the only antiarrhythmic drugs that have been demonstrated to reduce mortality in patients with VT or complex VA. Radiofrequency catheter ablation of VT has been beneficial in treating selected patients with arrhythmogenic foci of monomorphic VT. The automatic implantable cardioverter-defibrillator (AICD) is the most effective therapy for patients with life-threatening VT or ventricular fibrillation. The American College of Cardiology/American Heart Association Class I indications for an AICD are discussed. Other indications for an AICD are discussed. Patients with AICDs should be treated with biventricular pacing, not with dual-chamber rate-responsive pacing at a rate of 70/minute. |
7,465 | Functional status after operation for Ebstein anomaly: the Mayo Clinic experience. | The objective of this study was to review the long-term functional outcome of patients with Ebstein anomaly who had cardiac operation at our institution.</AbstractText>Ebstein anomaly is a spectrum of tricuspid valvular and right ventricular dysplasia. Many patients will require operation in an attempt to improve quality of life.</AbstractText>From April 1, 1972, to January 1, 2006, 539 patients with Ebstein anomaly underwent 604 cardiac operations at the Mayo Clinic in Rochester, Minnesota. Patient records were reviewed, and all patients known to still be alive were mailed a medical questionnaire or contacted by telephone.</AbstractText>At the initial operation at our institution, the mean age of the patients was 24 years (range 8 days to 79 years) and 53% were female patients. Survival at 5, 10, 15, and 20 years was 94%, 90%, 86%, and 76%, respectively. Survival free of late reoperation was 86%, 74%, 62%, and 46% at 5, 10, 15, and 20 years, respectively. Surveys were returned by 285 of 448 (64%) patients known to be alive at the time of this study. Two hundred thirty-seven (83%) patients were in New York Heart Association functional class I or II, and 34% were taking no cardiac medication. One hundred three patients (36%) reported an incident of atrial fibrillation or flutter, 5 patients (2%) reported having had endocarditis, and 1 patient (<1%) reported having a stroke. There were 275 pregnancies among 82 women. The recurrence of congenital heart disease was reported in 9 of 232 (3.9%) liveborn children.</AbstractText>Patients have good long-term survival and functional outcomes after undergoing surgery for Ebstein anomaly. Atrial arrhythmias are common both before and after surgery. Many patients have had one or more successful pregnancies with a low-recurrence risk of congenital heart disease.</AbstractText> |
7,466 | Atrial-selective sodium channel blockers: do they exist? | The risk of developing severe ventricular arrhythmias and/or organ toxicity by currently available drugs used to treat atrial fibrillation (AF) has prompted the development of atrial-selective antiarrhythmic agents. Until recently the principal focus has been on development of agents that selectively inhibit the ultra-rapid delayed rectifier outward potassium channels (I Kur), taking advantage of the presence of these channels in atria but not ventricles. Recent experimental studies have demonstrated important atrioventricular differences in biophysical properties of the sodium channel and have identified sodium channel blockers such as ranolazine and chronic amiodarone that appear to take advantage of these electrophysiologic distinctions and act to specifically or predominantly depress sodium channel-mediated parameters in "healthy" canine atria versus ventricles. Atrial-selective/predominant sodium channel blockers such as ranolazine effectively suppress AF in experimental models of AF involving canine isolated right atrial preparations at concentrations that produce little to no effect on ventricular electrophysiologic parameters. These findings point to atrial-selective sodium channel block as a new strategy for the management of AF. The present review examines our current understanding of atrioventricular distinctions between atrial and ventricular sodium channels and our understanding of the basis for atrial selectively of the sodium channel blockers. A major focus will be on the ability of the atrial-selective sodium channel blocking properties of these agents, possibly in conjunction with I Kur and/or I Kr blocking properties, to suppress and prevent the reinduction of AF. |
7,467 | Inward rectifier potassium currents as a target for atrial fibrillation therapy. | Subunits of inwardly rectifying potassium channels (Kir) are expressed in many different tissues of the human body. Inward rectifier currents expressed in the heart are constituted by pore-forming alpha-subunits of Kir2, Kir3, and Kir6 subfamilies. Characteristic properties of inward rectifiers comprise small outward conductances that nevertheless are important to terminal repolarization of cardiac action potentials. There is considerable difference in the regional expression of cardiac Kir channels, and subunits are additionally regulated by specific disease conditions. Resulting changes facilitate occurrence and persistence of atrial fibrillation (AF). For instance, upregulation of Kir2.1 protein and resultant current I K1 is a hallmark of AF-related ionic remodeling. Increased I K1 helps to stabilize atrial rotors, and current inhibition has accordingly been suggested as an antiarrhythmic approach for AF therapy. But there are caveats to I K1 inhibition per se, and there is no specific inhibitor of Kir2 channels. Modulation of I K1 rectification properties seems theoretically interesting for manipulation of Kir2 currents as an antiarrhythmic approach. Kir3-based muscarinic currents (I KACh) are functionally upregulated during AF through increased constitutive activity (passing current in the absence of an agonist). Upregulated I KACh supports sustenance of the arrhythmia. There is considerable intraatrial diversity in the expression of underlying Kir3.1/Kir3.4 subunits, but atrial-specific localization makes inhibition of this current a potentially interesting antiarrhythmic target devoid of ventricular side effects. Experimental studies of specific inhibitors indicate efficacy in various disease models. The role of I KATP remodeling under AF conditions has not been extensively studied, but present evidence indicates current downregulation and modulation of IKATP seems less promising than that of other inward rectifiers. |
7,468 | Electrocardiographic abnormalities in patients with acute burn injuries. | To determine the incidence and types of electrocardiographic (ECG) abnormalities in patients admitted with acute burn injuries and correlate them with the degree and the extent of burn injuries.</AbstractText>Retrospective analysis of 192 patients admitted to the burn unit was performed. Thirty-four patients met the inclusion criteria of having a 12-lead ECG performed on admission and at least one more time during their stay.</AbstractText>There were 26 men and 8 women. The average age of patients was 53.4 +/- 17.5 years. The average degree of burn was 2.4 +/- 0.6 and the average body surface area (BSA) involved was 12.8 +/- 11.8%. There were 18 patients (53%) with ECG abnormalities. Five patients had sinus tachycardia, including two with premature atrial complexes (PACs) and one with ST-T abnormality. Three patients had premature ventricular complexes (PVCs), including one with a paced atrial rhythm and one with a prolonged QT interval. Right bundle branch block was present in two patients, and low voltage QRS was present in one. Atrial fibrillation was present in two patients, including one with ST-T abnormality due to digitalis effect. Four patients had a prolonged QT interval as the sole abnormality. One patient had left ventricular hypertrophy, an old inferior myocardial infarct, PACs, and non-specific ST-T wave abnormality.</AbstractText>In patients with acute burn injuries sinus tachycardia and a prolonged QT interval were the most common ECG abnormalities. There was no correlation between the extent of burn injuries and observed ECG abnormalities. No patient had a life threatening arrhythmia, and all patients had a good outcome.</AbstractText> |
7,469 | Outcome after implantation of cardioverter defibrillator [corrected] in patients with Brugada syndrome: a multicenter Israeli study (ISRABRU). | Many electrophysiologists recommend implantable cardioverter defibrillators for patients with Brugada syndrome who are cardiac arrest survivors or presumed at high risk of sudden death (patients with syncope or a familial history of sudden death or those with inducible ventricular fibrillation at electrophysiologic study).</AbstractText>To assess the efficacy and complications of ICD therapy in patients with Brugada syndrome.</AbstractText>The indications, efficacy and complications of ICD therapy in all patients with Brugada syndrome who underwent ICD implantation in 12 Israeli centers between 1994 and 2007 were analyzed.</AbstractText>There were 59 patients (53 males, 89.8%) with a mean age of 44.1 years. At diagnosis 42 patients (71.2%) were symptomatic while 17 (28.8%) were asymptomatic. The indications for ICD implantation were: a history of cardiac arrest (n = 11, 18.6%), syncope (n = 31, 52.5%), inducible VF in asymptomatic patients (n = 14, 23.7%), and a family history of sudden death (n = 3, 0.5%). The overall inducibility rates of VF were 89.2% and 93.3% among the symptomatic and asymptomatic patients, respectively (P = NS). During a follow-up of 4-160 (45 +/- 35) months, all patients (except one who died from cancer) are alive. Five patients (8.4%), all with a history of cardiac arrest, had appropriate ICD discharge. Conversely, none of the patients without prior cardiac arrest had appropriate device therapy during a 39 +/- 30 month follow-up. Complications were encountered in 19 patients (32%). Inappropriate shocks occurred in 16 (27.1%) due to lead failure/dislodgment (n = 5), T wave oversensing (n = 2), device failure (n = 1), sinus tachycardia (n = 4), and supraventricular tachycardia (n = 4). One patient suffered a pneumothorax and another a brachial plexus injury during the implant procedure. One patient suffered a late (2 months) perforation of the right ventricle by the implanted lead. Eleven patients (18.6%) required a reintervention either for infection (n = 1) or lead problems (n = 10). Eight patients (13.5%) required psychiatric assistance due to complications related to the ICD (mostly inappropriate shocks in 7 patients).</AbstractText>In this Israeli population with Brugada syndrome treated with ICD, appropriate device therapy was limited to cardiac arrest survivors while none of the other patients including those with syncope and/or inducible VF suffered an arrhythmic event. The overall complication rate was high.</AbstractText> |
7,470 | Oral anticoagulation in patients with cardiomyopathy or heart failure in sinus rhythm. | Despite many prospective randomized studies defining the benefits of anticoagulation in atrial fibrillation (AF), there have been no adequate studies in cardiomyopathy (CM) in sinus rhythm.</AbstractText>We review the current knowledge of the risk of stroke in CM, left ventricular systolic dysfunction and heart failure as well as the indications for antithrombotic agents and compare this with AF.</AbstractText>The current knowledge of risk factors for stroke and indications for antithrombotic agents in CM is similar to that of AF prior to the treatment studies of the 1980s-1990s.</AbstractText>Prospective randomized trial data are urgently needed to determine the role of antithrombotic drugs in CM.</AbstractText>Copyright 2008 S. Karger AG, Basel.</CopyrightInformation> |
7,471 | Radiofrequency ablation of drug-refractory atrial fibrillation: an observational study comparing 'ablate and pace' with pulmonary vein isolation. | To compare clinical characteristics, procedure complexity, acute and long-term outcome of 'ablate and pace' (A&P) with pulmonary vein isolation (PVI) in patients with drug-refractory atrial fibrillation (AF). So far, only few small studies have compared the two procedures.</AbstractText>We analysed retrospectively a cohort of symptomatic consecutive patients with drug-refractory AF. Group 1 included 100 patients treated with A&P and Group 2 included 144 patients treated with PVI. Group 1 patients were older (74 +/- 8 vs. 56 +/- 9 years; P < 0.0001), had lower left ventricular ejection fraction (50 +/- 13% vs. 59 +/- 7%; P < 0.05), and a lower prevalence of paroxysmal AF (46% vs. 65%; P < 0.05). Acute success was not statistically different (98% vs. 92.3%, P = ns). Group 1 patients had shorter procedure time and lower radiation exposure with respect to Group 2 patients (70 +/- 15 vs. 204 +/- 58 min, and 8 +/- 4 vs. 57 +/- 22 min; P < 0.0001, respectively). After a median follow-up of 29 months (I, III quartile; 15, 40 months) vs. 25 months (I, III quartile; 8, 36 months) (P = ns), all the patients in Group 1 were free of symptomatic AF, while 113 patients (79%) of Group 2 were in stable sinus rhythm (P < 0.0001). Persistent or permanent AF has been documented in 58 patients (58%) of Group 1 vs. 11 (8%) of Group 2 (P < 0.0001).</AbstractText>In this series (i) patients treated with A&P and PVI for drug-refractory AF showed significant differences in clinical profile; (ii) A&P is a shorter and less complex procedure, but is associated with a higher rate of persistent AF; (iii) symptomatic recurrences of paroxysmal AF were more frequent in PVI group. Randomized studies appear necessary to identify the best strategy in selected cases.</AbstractText> |
7,472 | Regional endocardial left atrial voltage and electrogram fractionation in patients with atrial fibrillation. | Heterogeneities in electrophysiological properties may contribute to the development of atrial fibrillation, and regional disparities in endocardial voltage in the left atrium have been related to arrhythmogenic mechanisms. This study aimed at investigating endocardial voltage in different regions of the left atrium in patients with atrial fibrillation (AF).</AbstractText>Thirty-six patients (aged 56 +/- 7 years, 10 female) scheduled for circumferential ablation for paroxysmal AF were studied. Voltage measurements were performed during AF and with constant right ventricular pacing in the anterior, posterior, superior and inferior walls outside the antrum of the left (LPV), and right (RPV) pulmonary veins, by means of electroanatomical mapping. There was a high agreement among measurements performed in the endocardium of the posterior atrial wall (ICC > 0.70), and moderate agreement among measurements performed in the superior and inferior walls (0.50 < ICC< 0.70), outside both PV antra. The posterior left atrial wall demonstrated significantly higher voltages both outside the LPV antrum (1.29 +/- 1.36 mV) and the RPV antrum (1.20 +/- 0.63 mV) compared to the inferior, anterior and superior walls (0.47 +/- 0.49, 0.68 +/- 0.69, and 0.61 +/- 0.83 mV outside the LPV antrum, and 0.39 +/- 0.23, 0.65 +/- 0.49, and 0.49 +/- 0.24 mV outside the RPV antrum, respectively). Fractionated electrograms were mainly identified at the posterior left atrial wall, outside the right PV antrum.</AbstractText>During AF, the posterior wall displays significantly higher voltage and electrogram fractionation compared with other parts of the left atrial endocardium outside the antra of both pulmonary veins in patients with paroxysmal AF.</AbstractText> |
7,473 | Diagnostic tools for atrial tachyarrhythmias in implantable pacemakers: a review of technical options and pitfalls. | Correct pacemaker (PM) diagnosis of paroxysmal atrial tachyarrhythmias is crucial for their prevention and intervention with specific atrial pacing programmes. The PM mode switch to only ventricular pacing after detection of atrial tachyarrhythmias is often used as the parameter to quantify the 'burden' of atrial tachyarrhythmias.</AbstractText>This review addresses potential errors in the detection and diagnosis of atrial tachyarrhythmias, sometimes resulting in incorrect mode switches. The interpretation of PM-stored data of patients with atrial tachyarrhythmias and the results of trials of pace prevention and intervention can be better appreciated with more insight into the technical options and pitfalls.</AbstractText>Literature and clinical experience demonstrate that the correctness of PM-derived diagnosis of atrial tachyarrhythmias depends on 1) the sensitivity setting to detect the onset and perpetuation of atrial tachyarrhythmias frequently characterised by variable and low-voltage signals, 2) the rejection of far-field R wave sensing by the atrial sense amplifier, 3) the facility for verification of mode switches by a high-quality intracardiac registration of the nonmodified atrial electrogram. The configuration of the atrial lead also contributes to the diagnostic performance of the PM.</AbstractText>Not only pacing algorithms and diverse technical PM features but also the atrial lead configuration are currently the limiting factors to the fully reliable, automated detection and diagnosis of atrial tachyarrhythmias. If these technical shortcomings can be improved, better signal processing will result. Then atrial pacing to prevent or suppress atrial tachyarrhythmias will be more justified. (Neth Heart J 2008;16:201-10.).</AbstractText> |
7,474 | Off-pump coronary artery bypass in multi-vessel disease: effect of ejection fraction on early and midterm mortality and morbidity. | Left ventricular function is an independent predictor of operative mortality. The outcome of myocardial revascularization is greatly affected by the severity of impairment of cardiac function. The present study was undertaken to find the early and midterm mortality and morbidity among patients with different degrees of myocardial function undergoing off-pump bypass.</AbstractText>Hundred and forty two patients with isolated coronary revascularization were divided into three groups according to left ventricle ejection fraction (LVEF). Forty eight patients with LVEF<30% (group I), 48 patients with LVEF between 30-40% (group II), and 46 patients with LVEF >40% (group III). Clinical, operative and post operative outcome were compared. Patients were followed up to find midterm survival and control of symptoms.</AbstractText>The mean age for the patients observed was 56.5+/-9.8 years. Preoperative predicted mortality according to euroSCORE was much higher in group I due to high incidence of preoperative heart failure and recent myocardial infarction. The extent of coronary vessel involvement was similar among the three groups, but those in group III had more single vessel disease. The number of grafts performed per patient was lowest in group I (1.7+/-0.6) and highest in group III (2.0+/-0.6) P=0.03. Overall hospital mortality was 4.2%.The mean euroSCORE of patients who died was 18.7+/-22.5. All in-hospital mortality was among patients who belonged to the high risk group I, 6 (12.5%). Morbidity was similar among all groups. The incidence of myocardial infarction, atrial fibrillation, and acute renal failure were slightly higher in group I; 95.6% of patients were followed up for 7-69 months (mean 27.6+/-17.6). The incidence of angina in group I, II, and III was 20%, 6.5%, and 2.2%. Symptomatic heart failure was seen in 17.5% in group I, 6.5% in group II, and 2.2% in group III. Cardiac interventions among group I, II, III was 12.5%, 4.3% and 2.3% respectively. Redo coronary artery bypass CABG was higher in group II (4.3%) compared to 2.5% in group I. Late mortality was similar among all groups.</AbstractText>Off-pump bypass can be used safely among patients with different degrees of myocardial function. The results of surgery were better than the preoperative predicted euroSCORE. Early mortality and morbidity were directly related to ejection fraction .This is true only when LVEF is below 30%. Midterm mortality was similar among different risk groups.</AbstractText> |
7,475 | Early predictors of outcome in comatose survivors of ventricular fibrillation and non-ventricular fibrillation cardiac arrest treated with hypothermia: a prospective study. | Current indications for therapeutic hypothermia (TH) are restricted to comatose patients with cardiac arrest (CA) due to ventricular fibrillation (VF) and without circulatory shock. Additional studies are needed to evaluate the benefit of this treatment in more heterogeneous groups of patients, including those with non-VF rhythms and/or shock and to identify early predictors of outcome in this setting.</AbstractText>Prospective study, from December 2004 to October 2006.</AbstractText>32-bed medico-surgical intensive care unit, university hospital.</AbstractText>Comatose patients with out-of-hospital CA.</AbstractText>TH to 33 +/- 1 degrees C (external cooling, 24 hrs) was administered to patients resuscitated from CA due to VF and non-VF (including asystole or pulseless electrical activity), independently from the presence of shock.</AbstractText>We hypothesized that simple clinical criteria available on hospital admission (initial arrest rhythm, duration of CA, and presence of shock) might help to identify patients who eventually survive and might most benefit from TH. For this purpose, outcome was related to these predefined variables. Seventy-four patients (VF 38, non-VF 36) were included; 46% had circulatory shock. Median duration of CA (time from collapse to return of spontaneous circulation [ROSC]) was 25 mins. Overall survival was 39.2%. However, only 3.1% of patients with time to ROSC > 25 mins survived, as compared to 65.7% with time to ROSC < or = 25 mins. Using a logistic regression analysis, time from collapse to ROSC, but not initial arrest rhythm or presence of shock, independently predicted survival at hospital discharge.</AbstractText>Time from collapse to ROSC is strongly associated with outcome following VF and non-VF cardiac arrest treated with therapeutic hypothermia and could therefore be helpful to identify patients who benefit most from active induced cooling.</AbstractText> |
7,476 | [Dynamic of the changes of the paced QT dispersion after ventricular pacemaker implantation (WIR) and radiofrequency atrioventricular junction ablation in drug refractory atrial fibrillation]. | Transcutaneous RF catheter ablation of the atrioventricular junction (AVJ) in pts with ventricular pacemaker (VVIR) implantated is an accepted treatment for drug-intolerant or drug refractory atrial fibrillation. The ventricular arrhythmias and sudden cardiac death may be associated with increased of QT dispersion (QTD), mainly in pts with reduced LV function (low ejection fraction - EF) after AVJ ablation. The present study evaluates the dynamic of the changes of QTD in response to a sudden pacing rate drop from 80/min to 40/min in follow up 1 day, 3, 6 and 9 months after ablation (1d, 3m, 6m, 9m).</AbstractText>The 12-lead ECGs were recorded on 22 pts (mean age 72.6+/-5.4 yrs) (10 with low EF (<50%) - group A, 12 with normal EF (> or =50%) - group B) on the 1 day, 3, 6 and 9 months following AVJ ablation during a sudden drop in ventricular pacing rate from 80 to 40 beats/min. The maximum QT interval (QTM), minimum QT interval (QTm), and QTD were measured on the last 5 beats prior to the rate drop (QTM-80, QTm-80, QTD-80) and on the first 5 beats after the rate drop (QTM-40, QTm-40, QTD-40). These QT parameters were compared. The echocardiographical studies were performed on the 1d, 3m, 6m and 9m following AVJ ablation.</AbstractText>In response to a sudden paced heart rates drop from 80 to 40 beats/min, the DeltaQTM (QTM-40 - QTM-80) increased during follow-up in both groups, while the DeltaQTm (QTm-40-QTm-80) increased in group B(23.3+/-25.7 in 1d, 27,5+/-20.1ms in 9m; p< 0.001), but not in group A (1+/-16.6 in 1d, 5+/-25.1ms in 9m). Consequently, the AQTD (QTD-40 - QTD-80) increased significantly in group A at 6 months (29+/-31.1ms; p<0.05) but not in group B (9.2+/-17.3msl. The negative correlation between QTD-40, QTD-80 and EF was observed in group A.</AbstractText>Following AVJ ablation, QTD increased during a sudden rate drop in pts with reduced LV function, but not in pts with EF > or = 50%. The significant correlation between QTD and paced rate was found in pts with LV dysfunction. The increased QTD in response to a sudden heart rate drop in pts with low EF was due to a failure of the expected prolongation of the QTm.</AbstractText> |
7,477 | Morphology discrimination in implantable cardioverter-defibrillators: consistency of template match percentage during atrial tachyarrhythmias at different heart rates. | Morphology discrimination (MD) in implantable cardioverter-defibrillators (ICDs) is based on the comparison of the ventricular electrogram during tachycardia with a stored reference template obtained during baseline rhythm. However, the effect of heart rate on the template match percentage during supraventricular tachyarrhythmias (SVT) is not known. The purpose of this study was to evaluate the performance of the template match percentage during SVT at different heart rates.</AbstractText>Stored electrograms of 868 tachyarrhythmias from 88 patients with a dual-chamber ICD (St Jude Medical, USA) were analysed by the investigators. The effect of heart rate on template match percentage was estimated by regression analysis. For performance measures, data were corrected for multiple episodes in a patient by using the generalized estimating equation method. The mean template match percentage was 86.6 +/- 22.2% (median 100%) for SVT episodes. No significant differences in template match percentage between fast [ventricular cycle length (CL) 300-350 ms] and slow (ventricular CL >400 ms) SVTs were observed (85.4 +/- 27.0 vs. 87.1 +/- 19.7%). Using nominal settings, MD alone provided sensitivity and specificity of 70.2% and 89.4% overall, respectively. Morphology discrimination in conjunction with rate branch analysis, sudden onset, and stability yielded sensitivity and specificity of 98.5% and 91.2%, respectively.</AbstractText>Morphology discrimination has a consistently high template match percentage during SVTs, which is independent of ventricular CL. The consistent high match percentage results in high specificity for arrhythmia discrimination.</AbstractText> |
7,478 | Prognostic value of short-deceleration time of mitral inflow E velocity: implications in patients with atrial fibrillation and left-ventricular systolic dysfunction. | The aim of this prospective study was to evaluate the contribution of an initially shortened deceleration time of mitral inflow E velocity (E-wave DT) to predict survival in patients with left-ventricular (LV) systolic dysfunction in atrial fibrillation (AF) and in sinus rhythm (SR).</AbstractText>To date, few data are available concerning the prognostic value of Doppler mitral profile in patients with AF, particularly in the presence of LV systolic dysfunction.</AbstractText>We studied the outcome of 140 consecutive patients with LV ejection fraction less than 40%. Complete history, physical examination and echocardiography were performed.</AbstractText>Chronic AF was present in 40 (29%) patients. Over a mean follow-up of 25+/-11 months, 54 (39%) patients died, 18 in the AF group and 36 in the SR group. Ejection fraction was similar in the two groups (31% versus 32%, respectively). Survival curves indicated a significantly poorer prognosis for shortened E-wave DT less than 150 ms in the AF group and in the SR group (both p<or=0.01). Using multivariable Cox analysis, shortened E-wave DT was identified as an independent predictor of mortality in the AF group (exponential of coefficient: 0.97; chi-square: 5.82; p=0.01) and in the SR group (exponential of coefficient: 0.98; chi-square: 5.82; p=0.001).</AbstractText>In patients with LV systolic dysfunction, a shortened deceleration time E-wave on Doppler examination appears to predict a similar poor prognosis in patients with AF as with SR.</AbstractText> |
7,479 | Localized left atrial administration of tPA for the treatment of mechanical mitral valve thrombosis. | Prosthetic valve thrombosis is a dangerous and unfortunately not uncommon medical situation, often seen as a medical emergency. Patients with previously unseen and more confounding medical problems are presenting, making the decision regarding therapeutic options even more complicated. In this case report, we describe a complicated patient with mechanical mitral valve prosthesis placed secondary to rheumatic heart disease, with multiple co-morbidities including severe left ventricular dysfunction, permanent atrial fibrillation, left femoral deep vein thrombosis, and non-sustained ventricular tachycardia, who presented with acute valve thrombosis. The patient' history of hemorrhagic stroke and multiple acute ischemic strokes represented an absolute contraindication to more conventional forms of therapy such as intravenous systemic thrombolytics. In the following case report, we present an unprecedented approach to prosthetic valve thrombosis in this seemingly no-option patient. |
7,480 | Angiographic and clinical manifestations of coronary fistulas in Chinese people: 15-year experience. | Coronary artery fistula (CAF) is an anomaly resulting in the steal phenomenon of coronary blood flow, which may cause morbidity or mortality. CAFs in Chinese patients after long-term follow-up of 15 years were retrospectively analyzed.</AbstractText>From September, 1992 to August, 2007, 152 CAFs were detected in 28,210 coronary angiograms from 125 patients. Clinical and angiographic data of all patients were analyzed retrospectively. Two types of CAFs were characterized: type I in 99 patients with 124 solitary coronary to cardiac chamber or great vessel fistula; type II: 26 patients with 28 coronary artery--left ventricular multiple microfistulas. Single-, double-, and triple-CAFs were detected in 79%, 20%, and 1% of patients, respectively. Coexistent coronary lesions were noted in 41% of patients. Fistula-related symptoms included stable angina in 55, myocardial infarction in 2, heart failure in 2, sudden death with ventricular fibrillation in 1, and syncope in 1. Twenty-four patients had coexistent congenital anomalies. Only 9 patients underwent coronary intervention or/and surgery for CAFs.</AbstractText>CAFs may cause trivial or lethal cardiac events, and may coexist with coronary lesion or congenital anomaly. Coronary to cardiac chamber or great vessel fistula and coronary-left ventricular multiple microfistulas have different morphologic and pathological phenomena.</AbstractText> |
7,481 | Role of potassium currents in cardiac arrhythmias. | Abnormal excitability of myocardial cells may give rise to ectopic beats and initiate re-entry around an anatomical or functional obstacle. As K(+) currents control the repolarization process of the cardiac action potential (AP), the K(+) channel function determines membrane potential and refractoriness of the myocardium. Both gain and loss of the K(+) channel function can lead to arrhythmia. The former because abbreviation of the active potential duration (APD) shortens refractoriness and wave length, and thereby facilitates re-entry and the latter because excessive prolongation of APD may lead to torsades de pointes (TdP) arrhythmia and sudden cardiac death. The pro-arrhythmic consequences of malfunctioning K(+) channels in ventricular and atrial tissue are discussed in the light of three pathophysiologically relevant aspects: genetic background, drug action, and disease-induced remodelling. In the ventricles, loss-of-function mutations in the genes encoding for K(+) channels and many drugs (mainly hERG channel blockers) are related to hereditary and acquired long-QT syndrome, respectively, that put individuals at high risk for developing TdP arrhythmias and life-threatening ventricular fibrillation. Similarly, down-regulation of K(+) channels in heart failure also increases the risk for sudden cardiac death. Mutations and polymorphisms in genes encoding for atrial K(+) channels can be associated with gain-of-function and shortened, or with loss-of-function and prolonged APs. The block of atrial K(+) channels becomes a particular therapeutic challenge when trying to ameliorate atrial fibrillation (AF). This arrhythmia has a strong tendency to cause electrical remodelling, which affects many K(+) channels. Atrial-selective drugs for the treatment of AF without affecting the ventricles could target structures such as I(Kur) or constitutively active I(K,ACh) channels. |
7,482 | Episodic syncope in hypertrophic cardiomyopathy: evidence for inappropriate vasodilation. | Symptoms of impaired consciousness (syncope and pre-syncope) occur in 15-25% of patients with hypertrophic cardiomyopathy (HCM).1 In young patients a history of recurrent syncope is associated with an increased risk of sudden death.2(-)5 Syncope usually occurs without warning or symptoms suggestive of the cause. Detailed investigations identify a probable mechanism in a minority, usually paroxysmal atrial fibrillation or ventricular tachycardia. In the majority however no likely mechanism is found despite repeated 24-hour ambulatory echocardiography (ECG) or patient-activated monitoring, exercise testing and invasive electrophysiological studies.1 6 Empirical treatment with amiodarone, a pacemaker or an implantable cardioverter-defibrillator is commonly employed, but is often unsuccessful in relieving the symptoms. We have previously observed that approximately 30% of patients with HCM have abnormal blood pressure response during maximal upright exercise.7 8 This was due in the majority of patients to an exaggerated fall in systemic vascular resistance, possibly arising from abnormal activation of stretch-sensitive left ventricular mechanoreceptors,9 10 by a mechanism similar to that described in aortic stenosis.11 However, in some patients an inadequate cardiac output response to exercise may be responsible.12 We hypothesised that abnormal vasodepressor-mediated hypotension may also occur during daily life in patients with HCM, and that this may be an important mechanism of syncope when conventional investigations fail to reveal a cause. |
7,483 | Spatial-temporal filter effect in a computer model study of ventricular fibrillation. | Prediction of countershock success from ventricular fibrillation (VF) ECG is a major challenge in critical care medicine. Recent findings indicate that stable, high frequency mother rotors are one possible mechanism maintaining VF. A computer model study was performed to investigate how epicardiac sources are reflected in the ECG. In the cardiac tissues of two computer models - a model with cubic geometry and a simplified torso model with a left ventricle - a mother rotor was induced by increasing the potassium rectifier current. On the epicardium, the dominant frequency (DF) map revealed a constant DF of 23 Hz (cubic model) and 24.4 Hz (torso model) in the region of the mother rotor, respectively. A sharp drop of frequency (3-18 Hz in the cubic model and 12.4-18 Hz in the torso model) occurred in the surrounding epicardial tissue of chaotic fibrillatory conduction. While no organized pattern was observable on the body surface of the cubic model, the mother rotor frequency can be identified in the anterior surface of the torso model because of the chosen position of the mother rotor in the ventricle (shortest distance to the body surface). Nevertheless, the DFs were damped on the body surfaces of both models (4.6-8.5 Hz in the cubic model and 14.4-16.4 Hz in the torso model). Thus, it was shown in this computer model study that wave propagation transforms the spatial low pass filtering of the thorax into a temporal low pass. In contrast to the resistive-capacitive low pass filter formed by the tissue, this spatial-temporal low pass filter becomes effective at low frequencies (tens of Hertz). This effect damps the high frequency components arising from the heart and it hampers a direct observation of rapid, organized sources of VF in the ECGs, when in an emergency case an artifact-free recording is not possible. |
7,484 | [Cardioprotective, inotropic, and anti-arrhythmia properties of a complex adaptogen "Tonizid"]. | We have studied the new complex plant adaptogen preparation tonizid containing dry extracts of Aralia mandshurica, Panax ginseng, Rhodiola rosea, and Eleutherococcus senticosus. The course administration (5 days) of tonizid led to a decrease in the ratio of necrotic zone size/risk area during a 45-min local ischemia and a 2-hr reperfusion in artificially ventilated chloralose anaesthetized rats. This compound decreased the necrotic zone but did not change the size of the risk area. Tonizid also prevented an appearance of ventricular fibrillation during a 45-min coronary artery occlusion, but did not affect the incidence of ventricular arrhythmias during a brief ischemia and reperfusion. In a separate series of experiments, tonizid was administered during 5 days to rats with postinfarction cardiac sclerosis, which was formed 45 days after coronary artery occlusion. In this case, tonizid dose-dependently elevated the ventricular fibrillation threshold. The experiments in vitro were performed on a model of 35-min total ischemia and 30-min reperfusion of isolated rat heart using the Langendorff technique. The course administration of tonizid attenuated the reperfusion-induced decrease in the left ventricular pressure and the rate of contraction. However, tonizid did not prevent a reperfusion-induced reduction in the heart rate, a decrease in the rate of relaxation, and an increase in the final diastolic pressure. Tonizid decreased the creatine kinase levels in the venous effluent from isolated rat heart during reperfusion. At the same time, the plant adaptogen did not affect the incidence of ventricular arrhythmias and coronary flow. It is suggested that tonizid can be used as an adaptogen drug attenuating the contractility dysfunction and preventing an appearance of irreversible cardiomyocyte damage during ischemia and reperfusion. Tonizid exhibits cardioprotective and antifibrillatory properties during acute cardiac ischemia/reperfusion and postinfarction cardiac fibrosis. |
7,485 | Comparison of outcomes in patients undergoing defibrillation threshold testing at the time of implantable cardioverter-defibrillator implantation versus no defibrillation threshold testing. | Inability to perform defibrillation threshold (DFT) testing during implantable cardioverter defibrillator (ICD) implantation due to co-morbidities may influence long-term survival.</AbstractText>Retrospective review at The University of Michigan (1999-2004) identified 55 patients undergoing ICD implantation without DFT testing ("No-DFT group"). A randomly selected sample of patients (n = 57) undergoing standard DFT testing ("DFT group") was compared in terms of appropriate shocks, clinical shock efficacy and all-cause mortality.</AbstractText>DFT testing was withheld due to hypotension, atrial fibrillation with inability to exclude left atrial thrombus, left ventricular thrombus, CHF and/or ischemia. The No-DFT group had a similar appropriate shock rate, but lower total survival (69.1% vs. 91.2%, p = 0.004) than the DFT group. The No-DFT group had a higher incidence of ventricular fibrillation (VF) episodes (9.1% vs. 3.1%, p = 0.037), and deaths attributable to VF (3 of 17 deaths vs. 0 of 5 deaths) compared to the DFT group. Multivariate analysis found a trend toward increased risk of death in the No-DFT group (HR 3.18, 95% CI 0.82-12.41, p = 0.095) after adjusting for baseline differences in gender distribution, NYHA class and prior CABG.</AbstractText>In summary, overall mortality was higher in the No-DFT group. More deaths attributable to VF occurred in the No-DFT group. Thus, DFT testing should therefore remain the standard of care. Nevertheless, ICD therapy should not be withheld in patients who meet appropriate implant criteria simply on the basis of clinical scenarios that preclude routine DFT testing. (Cardiol J 2007; 14: 463-469).</AbstractText> |
7,486 | Is the combination therapy of IKr-channel blocker and left stellate ganglion block effective for intractable ventricular arrhythmia in a cardiopulmonary arrest patient? | We have previously reported that the defibrillation success rate of intravenous nifekalant hydrochloride (NIF), a pure IKr-channel (IKr: the rapid components of the delayed rectifier potassium current) blocker, was more than 75% for lidocaine-resistant ventricular tachycardia and fibrillation (VT/VF) in patients with out-of-hospital cardiopulmonary arrest (CPA). However, there was no effective treatment for the remaining 25% of patients in whom defibrillation was unsuccessful. We hypothesised that the combination therapy of NIF and left stellate ganglion block (LSGB) was useful for defibrillation in NIF-resistant VT/VF and investigated its efficacy in a retrospective study.</AbstractText>We investigated sequentially 272 out-of-hospital CPA patients treated at Tokai University between April and December 2006. VT/VF occurred in 55 patients on arrival or during cardiopulmonary resuscitation (CPR). On the basis of our CPR algorithm, NIF was administered (0.15-0.3 mg/kg, i.v.) after the first direct-current cardioversion. NIF-resistant VT/VFs were observed in 15 out of 55 patients and LSGB was performed on 11 of these with administration of NIF. Sinus rhythm was restored in 7 patients following LSGB (64%) and complete recovery was achieved in 2 patients. In the non-LSGB group, however, all the patients died.</AbstractText>The combination therapy of intravenous NIF and LSGB was useful for defibrillation in intractable VT/VF. It is a potential and innovative treatment strategy for IKr-channel blocker resistant VT/VF. (Cardiol J 2007; 14: 355-365).</AbstractText> |
7,487 | Dual-site right ventricular pacing. A rescue alternative in cardiac resynchronisation therapy implantation failure? More efficient stimulation for patients with borderline cardiac resynchronisation therapy indication? Less harmful ventricular pacing? | Permanent cardiac pacing is nowadays a widespread method for the cure of conduction system diseases, improving quality of life and often saving patients' lives. In the twentieth century, scientific efforts were focused on extending battery life, improving sensitivity and reliability, minimizing the dimensions of the device and restoring atrio-ventricular synchrony and rate response. However, there is more and more evidence for the deleterious influence of chronic right ventricular pacing especially apical (RVA) pacing. DANISH, MOST, CTOPP and DAVID trials have proven univocally that right ventricular pacing increases risk of heart failure, atrial fibrillation and even mortality in patients with chronic heart failure. Such knowledge inspires the quest for alternative pacing sites. Right ventricular outflow tract (RVOT) became the most favourable non-apical pacing site. Since 1995 there have been several reports concerning dual-site right ventricular pacing (DuVP: RVOT plus RVA pacing) proving its beneficial clinical and hemodynamic outcome especially in the case of unsuccessful left ventricle implantation for cardiac resynchronisation therapy (CRT). (Cardiol J 2007; 14: 224-231). |
7,488 | Repeated ventricular. | Few publications report the possibility of "torsade de pointes"" (TdP) type tachycardia and ventricular fibrillation occurring in patients with prolonged QT syndrome in the course of hypothyroidism. The authors present the case of a 51-year-old woman with Hashimoto disease and hypothyroidism, inadequately supplemented with L-thyroxine. This patient was admitted to the ward with symptoms of hypometabolic crisis. She was diagnosed with shock and had marked sinus bradycardia with a QT interval prolongation of 0.8 s and paroxysmal TdP-type ventricular tachycardia. TdP was triggered by R-on-T ventricular extrasystoles. Laboratory tests revealed profound hypothyroidism. As pharmacological treatment of the arrhythmia and bradycardia was ineffective, an endocavital electrode was introduced. As a result of ventricular stimulation with a frequency of 90/min, shortening of the QT interval and disappearance of the cardiac arrhythmia and cardiogenic shock symptoms were obtained. L-thyroxine was administered and two days later ventricular stimulation was discontinued. When corrected for heart rate, the QT interval (QTc) was 0.43 s and no QT prolongation was detected in the course of a follow-up period of several months, during which L-thyroxine supplementation was adequate. Hypothyroidism may be the cause of life-threatening arrhythmias secondary to acquired long QT syndrome. Ventricular electrostimulation proved to be a life-saving intervention in this case in which prolonged QT syndrome and ventricular cardiac arrhythmias complicated hypometabolic crisis. (Cardiol J 2007; 14: 198-201). |
7,489 | The management of Brugada syndrome patients. | Brugada syndrome is a congenital electrical disorder characterised by the appearance of distinctive QRST-T patterns in the right precordial leads and an increased risk of sudden death (SCD) in young healthy adults. Although chamber enlargement is not apparent in most cases, autopsy and histological investigations have revealed structural abnormalities. The typical Brugada ECG manifestation is often concealed and may be revealed by Class IC anti-arrhythmic agents with the effect of blocking the fast component of sodium channel currents. The syndrome may also be unmasked or precipitated by a febrile state, vagotonic agents, alpha-adrenergic agonists, beta-adrenergic blockers, tricyclic or tetracyclic antidepressants, a combination of glucose and insulin and hypokalaemia, as well as by alcohol and cocaine toxicity. Since the typical Brugada ECG pattern can be normalised by Class IA agents to block transient outward currents (I(to)) or by isoproterenol and cilostazol to boost calcium channel currents, they have been considered pharmacological therapies aimed at rebalancing the ion channel currents during cardiac depolarisation and repolarisation. Case studies by intra-cardiac mappingguided ablation in the right ventricular outflow tract and Purkinje network have shown evidence of eliminating the substrate of ventricular tachycardia/fibrillation (VT/VF) in Brugada syndrome, which may be used as an adjunct to device therapy to abort electrical storms. At present the most effective therapy to prevent sudden cardiac death in Brugada syndrome is an implantable cardioverter defibrillator. (Cardiol J 2007; 14: 97-106). |
7,490 | Lightning-induced ventricular fibrillation. | We present a case of a previously healthy 17 year-old white male boy scout who collapsed after a lightning strike, and was found to be in ventricular fibrillation when emergency medical services arrived. The ventricular fibrillation was defibrillated into sinus rhythm after a single direct current (DC) countershock. However, the patient has remained in coma. Commotio cordis, sudden cardiac death from low-energy chest wall impact, is a phenomenon in which an exactly timed and located blow on the chest during the cardiac cycle results in ventricular fibrillation. Commotio cordis and electrical shock can both result in ventricular arrhythmias. We speculate that in this patient, ventricular fibrillation began immediately after the lightning, which probably struck at the peak of the T wave. (Cardiol J 2007; 14: 91-94). |
7,491 | Telecardiology applied to a region-wide public emergency health-care service. | To assess feasibility and reliability of telecardiology technologies applied to a region-wide public emergency health-care service.</AbstractText>About 27,841 patients from all over Apulia (19.362 km(2), 4 million inhabitants) were referred from October 2004 until April 2006 to public emergency health-care number "118" and underwent ECG evaluation according to a previously fixed inclusion protocol. Data recorded were transmitted with mobile telephone support to a telecardiology "hub" active 24-h a day. Hospitalization or further examinations were arranged by emergency physicians on the basis of ECG diagnosis and consultation.</AbstractText>Thirty-nine percent of patients complained of chest pain (CP) or epigastric pain, 26% loss of consciousness, 10% breathlessness, and 7% palpitations. Atrial fibrillation (AF) was diagnosed in 11.68% of patients and ST-elevation acute myocardial infarction (STEMI) in 1.91%. Among patients with CP, ECG showed STEMI in only 3.84% of cases, theoretically eligible for fibrinolysis or primary PCI; patients with STEMI complained of CP in 78.94% of cases. Of the patients, 65.28% with STEMI were from small towns without coronary care units, thus benefiting from an immediate pre-hospital diagnosis. Among patients with palpitations, only 10.27% of subjects showed ECG signs of supra-ventricular tachycardia and 25.18% of AF; other subjects avoided further improper hospitalization or emergency department monitoring.</AbstractText>This first region-wide leading experience shows the feasibility and reliability of telecardiology applied to a public emergency health-care service. Telemedicine protocols would probably be useful in lowering the number of improper hospitalizations and shortening delay in the diagnosis process of some heart diseases.</AbstractText> |
7,492 | The effects of dietary hempseed on cardiac ischemia/reperfusion injury in hypercholesterolemic rabbits. | Hempseed is a novel functional food that contains several health-promoting polyunsaturated fatty acids (PUFAs). PUFAs, such as those found in flaxseed and fish, have been shown to protect the heart against arrhythmias following ischemia/reperfusion.</AbstractText>TO INVESTIGATE THE POTENTIAL OF DIETARY HEMPSEED AS A CARDIOPROTECTIVE AGENT AGAINST GLOBAL ISCHEMIA AND SUBSEQUENT REPERFUSION BY ASSESSING SEVERAL MEASUREMENTS OF CARDIAC PERFORMANCE: QT interval duration, left ventricular pressure, arrhythmia incidence and arrhythmia duration.</AbstractText>MALE NEW ZEALAND WHITE RABBITS WERE FED ONE OF SIX DIETS: a control diet; or one supplemented with 10% hempseed, 10% delipidated hempseed, 0.5% cholesterol, 0.5% cholesterol plus 10% hempseed or 5% coconut oil. After eight weeks on their respective diets, the hearts were excised and subjected to 30 min of global ischemia and 45 min of reperfusion. Electrocardiogram traces were recorded throughout the experiment and were subsequently analyzed for QT interval duration, left ventricular pressure, arrhythmia incidence and arrhythmia duration. Plasma and cardiac tissue were analyzed for fatty acid content and composition.</AbstractText>Cholesterol-fed animals exhibited significantly higher PUFA levels in their plasma, but this did not directly translate into higher PUFA levels in their cardiac fractions. There were no significant differences among the groups in the incidence or duration of ischemia-derived arrhythmias. During reperfusion, there was a significant decrease in the incidence of fibrillation in the hearts obtained from cholesterol-fed and hempseed- plus cholesterol-fed rabbits compared with the hearts from delipidated hempseed-fed rabbits.</AbstractText>Dietary hempseed induced limited beneficial effects on cardiac function during ischemia/reperfusion challenge. The present study does not support the use of dietary hempseed to protect the heart during ischemic insult in this experimental model.</AbstractText> |
7,493 | Atrial conduction delay and its association with left atrial dimension, left atrial pressure and left ventricular diastolic dysfunction in patients at risk of atrial fibrillation. | Atrial conduction delay and its association with left atrial dimension, left atrial pressure and left ventricular (LV) diastolic dysfunction in patients at risk of atrial fibrillation (AF) may be assessed by high-resolution electrocardiography of P wave.</AbstractText>To determine how left atrial size, left atrial pressure and LV diastolic dysfunction, measured noninvasively by transthoracic echocardiography, influence atrial conduction time.</AbstractText>Signal-averaged electrocardiography of P wave and echocardiogram were performed on 70 patients (average age of 63+/-10 years; 37 male and 33 female), divided into three groups: group A, patients with paroxysmal AF (n=29); group B, patients with type 2 diabetes mellitus and arterial hypertension, but without AF (n=23); and group C, healthy control patients (n=18). Standard statistical methods were used.</AbstractText>Filtered P wave duration, measured by signal-averaged electrocardiography, was significantly prolonged in group A and group B compared with control group C (138+/-12 ms and 125+/-9 ms versus 117+/-8 ms; P </= 0.001 and P </= 0.01, respectively). Left atrial diameter, area and volume were significantly increased in group A compared with group C (P </= 0.01, P </= 0.05 and P </= 0.001, respectively), but no significant differences were found in these dimensions between group B and group C. Left atrial pressure, determined with the Doppler echocardiographic parameter ratio of early diastolic transmitral velocity to mitral annular early diastolic velocity, was significantly higher in group A, as well in group B, than group C (P </= 0.05, P </= 0.01). As well, impaired LV relaxation was present more often in group A (42%) and group B (50%).</AbstractText>Atrial conduction delay in patients at risk of AF (patients with diabetes and hypertension in group B) was associated with increased left atrial pressure and impaired LV relaxation. Patients with paroxysmal AF (group A) presented left atrial dilation, increased left atrial pressure and impaired LV relaxation, and these factors were associated with more significantly prolonged atrial conduction in group A than in group B.</AbstractText> |
7,494 | Remodelling of cardiac gap junction connexin 43 and arrhythmogenesis. | In cardiac muscle, the gap junction plays a pivotal role in electrical cell-to-cell coupling and impulse propagation between cells. The function of the gap junction depends on the regulation of connexin in the gap junction channel. A dysfunction of the gap junction is possibly caused by the downregulation of connexin or one of arrhythmogenic factors. The mechanisms of ventricular fibrillation, a lethal tachyarrhythmia, have been studied in relation to the remodelling of connexin.</AbstractText>To determine what type of connexin 43 (Cx43) remodelling contributes to the generation of ventricular fibrillation and what factors induce the modelling of Cx43.</AbstractText>Aconitine-induced ventricular fibrillation was induced in hearts isolated from adult rats. Alterations in the electrical activity, the phosphorylation of Cx43 and the expression of Cx43 were evaluated by both intracellular and extracellular recording of the action potentials, Western blotting and immunohistochemistry, respectively. Flutter activity after the application of aconitine shifted spontaneously to fibrillation, showing an electrical interaction between neighbouring cells in close proximity to one another. The facility of the shift from flutter to fibrillation was evaluated as a susceptibility of the heart to fibrillation in relation to gap junction function. The effects of phorbol 12-myristate 13-acetate, angiotensin II (AII) analogues, AII antagonists, the diabetic state, protein kinase A (PKA) activator, cyclic AMP analogues, d-sotalol (class III antiarrhythmic drug) and PKA inhibitors on the susceptibility of the heart to fibrillation were examined.</AbstractText>Pathological hearts with heterogeneous expression of Cx43 at the gap junction, such as phorbol 12-myristate 13-acetate-and AII analogue-treated hearts, as well as diabetic hearts, showed a significantly higher susceptibility to fibrillation. On the other hand, hearts with augmentative expression of Cx43 at the gap junction, such as hearts pretreated with a PKA activator, a cyclic AMP analogue (8-bromo-cyclic AMP) or d-sotalol, showed a significantly lower susceptibility to fibrillation. At the beginning of fibrillation, an increase in the cardiac tissue AII level, an augmentation of the protein kinase C (PKC)-epsilon activity, the presence of PKC-mediated hyperphosphorylation, a suppression of the PKA-mediated phosphorylation of Cx43 and a reduction in the expression of Cx43 at the gap junction were observed. These alterations in Cx43 expression were also observed to increase as the fibrillation advanced.</AbstractText>Augmentation of PKC-mediated phosphorylation and suppression of PKA-mediated phosphorylation induces the downward remodelling of Cx43. Such remodelling of Cx43 induces asynchronous electrical activities and makes the ventricular tissue susceptible to fibrillation. PKC is activated by AII. The fibrillation itself remodels Cx43, thereby causing a vicious cycle. As a result, PKC inhibitors, AII antagonists and PKA activators are considered to possibly have a protective effect against the initiation or advancement of ventricular fibrillation.</AbstractText> |
7,495 | Moderate physical exercise: a simplified approach for ventricular rate control in older patients with atrial fibrillation. | This prospective pilot-study was performed to assess whether regular moderate physical activity elevates the parasympathetic tone to the atrio-ventricular node and decreases VR during permanent AF.</AbstractText>Adequate ventricular rate (VR) control in patients with permanent atrial fibrillation (AF) is not easy to accomplish.</AbstractText>10 patients (mean age 59 +/- 10 years) with permanent AF (duration: 10 +/- 8 years) underwent moderate physical exercise adjusted to their individual physical capability (45 min walking/jogging twice a week). To analyze VR control physical exercise tests and Holter-ECG recordings were performed before and after 4 months. In addition, stepwise lactate tests and psycho-pathometric examinations were obtained.</AbstractText>After 4 months of training, there was a trend toward a decrease of mean VR in 24 h Holter-ECGs by 12% from 76 +/- 20 to 67 +/- 12 bpm (P = 0.05) while there was no significant decrease of the minimal VR (38 +/- 8 vs. 36.3 +/- 4.5 bpm, P = 0.54). At a lactate threshold of 2 mmol/l there was a trend towards an increase of the running speed from 105 +/- 11 to 116 +/- 12 m/min (P = 0.05). A significant VR decrease of 8% (range 5-10%) was observed at almost all exercise levels during exercise treadmill testing. Increases of exercise capacity and decreases of VR were accompanied by subjective improvements of health perception.</AbstractText>Regular moderate physical activity decreases VR at rest and during exercise while increasing exercise capacity. Physical training should be taken into account for ventricular rate control during AF.</AbstractText> |
7,496 | Antithrombotic therapy in atrial fibrillation: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). | This chapter about antithrombotic therapy in atrial fibrillation (AF) is part of the American College of Chest Physicians Evidence-Based Guidelines Clinical Practice Guidelines (8th Edition). Grade 1 recommendations indicate that most patients would make the same choice and Grade 2 suggests that individual patient's values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2008; 133[suppl]:123S-131S). Among the key recommendations in this chapter are the following (all vitamin K antagonist [VKA] recommendations have a target international normalized ratio [INR] of 2.5; range 2.0-3.0, unless otherwise noted). In patients with AF, including those with paroxysmal AF, who have had a prior ischemic stroke, transient ischemic attack (TIA), or systemic embolism, we recommend long-term anticoagulation with an oral VKA, such as warfarin, because of the high risk of future ischemic stroke faced by this set of patients (Grade 1A). In patients with AF, including those with paroxysmal AF, who have two or more of the risk factors for future ischemic stroke listed immediately below, we recommend long-term anticoagulation with an oral VKA (Grade 1A). Two or more of the following risk factors apply: age >75 years, history of hypertension, diabetes mellitus, moderately or severely impaired left ventricular systolic function and/or heart failure. In patients with AF, including those with paroxysmal AF, with only one of the risk factors listed immediately above, we recommend long-term antithrombotic therapy (Grade 1A), either as anticoagulation with an oral VKA, such as warfarin (Grade 1A), or as aspirin, at a dose of 75-325 mg/d (Grade 1B). In these patients at intermediate risk of ischemic stroke we suggest a VKA rather than aspirin (Grade 2A). In patients with AF, including those with paroxysmal AF, age < or =75 years and with none of the other risk factors listed above, we recommend long-term aspirin therapy at a dose of 75-325 mg/d (Grade 1B), because of their low risk of ischemic stroke. For patients with atrial flutter, we recommend that antithrombotic therapy decisions follow the same risk-based recommendations as for AF (Grade 1C). For patients with AF and mitral stenosis, we recommend long-term anticoagulation with an oral VKA (Grade 1B). For patients with AF and prosthetic heart valves we recommend long-term anticoagulation with an oral VKA at an intensity appropriate for the specific type of prosthesis (Grade 1B). See CHEST 2008; 133(suppl):593S-629S. For patients with AF of > or =48 h or of unknown duration for whom pharmacologic or electrical cardioversion is planned, we recommend anticoagulation with an oral VKA, such as warfarin, for 3 weeks before elective cardioversion and for at least 4 weeks after sinus rhythm has been maintained (Grade 1C). For patients with AF of > or = 48 h or of unknown duration undergoing pharmacological or electrical cardioversion, we also recommend either immediate anticoagulation with unfractionated IV heparin, or low-molecular-weight heparin (LMWH), or at least 5 days of warfarin by the time of cardioversion (achieving an INR of 2.0-3.0) as well as a screening multiplane transesophageal echocardiography (TEE). If no thrombus is seen, cardioversion is successful, and sinus rhythm is maintained, we recommend anticoagulation for at least 4 weeks. If a thrombus is seen on TEE, then cardioversion should be postponed and anticoagulation should be continued indefinitely. We recommend obtaining a repeat TEE before attempting later cardioversion (Grade 1B addressing the equivalence of TEE-guided vs non-TEE-guided cardioversion). For patients with AF of known duration <48 h, we suggest cardioversion without prolonged anticoagulation (Grade 2C). However, in patients without contraindications to anticoagulation, we suggest beginning IV heparin or LMWH at presentation (Grade 2C). |
7,497 | Chronic carbon monoxide exposure increases electrocardiographic P-wave and QT dispersion. | We investigated the association between chronic carbon monoxide (CO) exposure and electrocardiographic maximum/minimum P-wave duration (Pmax/Pmin), P-wave dispersion (Pd), maximum/minimum QT interval (QTmax/QTmin), and QT and corrected QT dispersion (QTd/cQTd), which are known as predictors of atrial fibrillation, ventricular arrhythmias, and sudden death. We obtained electrocardiograms of 48 apparently healthy male indoor barbecue workers (age mean +/- SD; 33.6 +/- 9.4) who were working in various restaurants for at least 3 yr and 51 age-matched healthy men (age mean +/- SD; 35.1 +/- 6.7). Average working time of the indoor barbecue workers in their jobs was 15.6 +/- 7.1 yr. P-wave parameters were analyzable in 39 barbecue workers and 40 control subjects and QT intervals were analyzable in 44 barbecue workers and 47 control subjects. Clinical characteristics of indoor barbecue workers and the control group were comparable in terms of age, sex, body mass index, blood pressure, heart rate, Pmin, and QTmin. However, COHb levels, Pmax, Pd, QTmax, QTd, and cQTd measurements were higher in indoor barbecue workers than in the control group (6.48 +/- 1.43 vs. 2.19 +/- 1.30, p < .001; 106.15 +/- 7.47 vs. 101.50 +/- 6.62, p < .005; 30.51 +/- 7.59 vs. 24.50 +/- 6.77, p < .001; 406.59 +/- 17.64 vs. 390.85 +/- 13.15, P < .001; 48.40 +/- 8.87 vs. 34.89 +/- 5.85, P < .001; 53.64 +/- 9.14 vs. 37.77 +/- 6.71, P < .001, respectively). In Pearson correlation analysis there were significant correlations between COHb level and Pd, QTmax, QTd, and cQTd (r = .315 P < .005; r = .402, P < .001, r = .573, P < .001, r = .615, P < .001, respectively). In conclusion, the present study is the first to assess and find an association between chronic CO exposure and electrocardiographic Pd and QTd/cQTd. |
7,498 | Prevention of ventricular arrhythmias with sarcoplasmic reticulum Ca2+ ATPase pump overexpression in a porcine model of ischemia reperfusion. | Ventricular arrhythmias are life-threatening complications of heart failure and myocardial ischemia. Increased diastolic Ca2+ overload occurring in ischemia leads to afterdepolarizations and aftercontractions that are responsible for cellular electric instability. We inquired whether sarcoplasmic reticulum Ca2+ ATPase pump (SERCA2a) overexpression could reduce ischemic ventricular arrhythmias by modulating Ca2+ overload.</AbstractText>SERCA2a overexpression in pig hearts was achieved by intracoronary gene delivery of adenovirus in the 3 main coronary arteries. Homogeneous distribution of the gene was obtained through the left ventricle. After gene delivery, the left anterior descending coronary artery was occluded for 30 minutes to induce myocardial ischemia followed by reperfusion. We compared this model with a model of permanent coronary artery occlusion. Twenty-four-hour ECG Holter recordings showed that SERCA2a overexpression significantly reduced the number of episodes of ventricular tachycardia after reperfusion, whereas no significant difference was found in the occurrence of sustained or nonsustained ventricular tachycardia and ventricular fibrillation in pigs undergoing permanent occlusion.</AbstractText>We show that Ca2+ cycling modulation using SERCA2a overexpression reduces ventricular arrhythmias after ischemia-reperfusion. Strategies that modulate postischemic Ca2+ overload may have clinical promise for the treatment of ventricular arrhythmias.</AbstractText> |
7,499 | Inflammatory factors that contribute to upregulation of ERG and cardiac arrhythmias are suppressed by CPU86017, a class III antiarrhythmic agent. | The aim of this study was to verify whether exaggerated arrhythmogenesis is attributed to inflammatory factors actively involving an excess of reactive oxygen species (ROS), transforming growth factor (TGF)-beta and endothelin (ET). We hypothesized that CPU86017, derived from berberine, which possesses multi-channel blocking activity, could suppress inflammatory factors, resulting in inhibition of over-expression of ether-a-go-go (ERG) and an augmented incidence of ventricular fibrillation (VF) in ischaemia/reperfusion (I/R). Rats with cardiomyopathy (CMP) induced by thyroxine (0.2 mg(-1)kg(-1) s.c. daily for 10 days) were treated with propranolol (10 mgkg(-1) p.o.) or CPU86017 (80 mgkg(-1) p.o.) on days 6-10. On the 11th day, arrhythmogenesis of the CMP was evaluated by I/R. In the CMP control group, an increase in VF incidence was found with the I/R episode, accompanied by increased ROS, which manifested as an increased level of malondialdehyde and decreased activities of SOD, glutathione peroxidase and catalase in the myocardium. Levels of inducible nitric oxide synthase and TGF-beta mRNA were increased in association with upregulation of preproET-1 and ET-converting enzyme. We found increased levels of ERG, which correlated well with arrhythmogenesis. Treatment with CPU86017 or propranolol reversed these changes. These experiments verified our hypothesis that the inflammatory factors ROS, iNOS, TGF-beta and ET-1 are actively involved in upregulation of ERG and arrhythmogenesis. CPU86017 and propranolol reduced VF by suppressing these inflammatory factors in the myocardium. |
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