Unnamed: 0 int64 0 2.34M | titles stringlengths 5 21.5M | abst stringlengths 1 21.5M |
|---|---|---|
9,300 | Effectiveness and long-term outcome of cardiopulmonary resuscitation in paediatric intensive care units in Spain. | To analyse the immediate effectiveness of resuscitation and long-term outcome of children who suffered a cardiorespiratory arrest when admitted to paediatric intensive care units (PICU).</AbstractText>Secondary analysis of data from an 18-month prospective, multicentre study analysing cardiorespiratory arrest in children in 16 paediatric intensive care units in Spain.</AbstractText>We studied 116 children between 7 days and 17 years of age. Data were recorded according to the Utstein style. Analysed outcome variables were sustained return of spontaneous circulation (ROSC), survival to hospital discharge and survival at 1 year. Neurological and general performance outcome was assessed by means of the Paediatric Cerebral Performance Category (PCPC) and the Paediatric Overall Performance Category (POPC) scales.</AbstractText>None.</AbstractText>In 80 patients (69%) ROSC was achieved and it was sustained > 20 min in 69 (59.5%). At one-year follow-up, 40 children (34.5%) were alive. Survival was not associated with sex, age or weight of patients. Mortality from cardiac arrest was higher than respiratory arrest (69.8% versus 40%, p = 0.01). Patients with sepsis had a higher mortality than other diagnostic groups. Mechanically ventilated children and those treated with vasoactive drugs had a higher mortality. Initial mortality was slightly higher in patients with slow ECG rhythms (35.7%) compared to those with ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) (27.2%). Duration of resuscitation effort was correlated with mortality (p < 0.0001). Patients who required one or more doses of adrenaline had also a higher mortality (77.8% versus 20.7%, p < 0.0001) and survivors needed less doses of adrenaline (0.85 +/- 1.14 versus 4.4+/-2.9, p < 0.0001). At hospital discharge 86.8 and 84.6% of patients had scores 1 or 2 (normal or near-normal) in the PCPC and POPC scales. At 1-year follow-up these figures were 90.8 and 86.3%, respectively.</AbstractText>One-third of children who suffer a cardiac or respiratory arrest when admitted to PICU survive, and most of them had a good long-term neurological and functional outcome. The duration of cardiopulmonary resuscitation attempts is the best indicator of mortality.</AbstractText> |
9,301 | [Modern pharmacotherapy of supraventricular and ventricular cardiac arrhythmia. An update for conventional therapy]. | Currently the pharmacological approach still represents the mainstay in the acute phase of arrhythmia management as well as in the chronic treatment phase of specific entities such as atrial fibrillation. However, non-pharmacological options have recently emerged as frequently used first-line tools for the treatment of various supraventricular and ventricular heart rhythm disturbances. Nevertheless, antiarrhythmic drug treatment is frequently used as a bridging or adjunctive therapy in conjunction with catheter ablation or implantable cardioverter defibrillators. Antiarrhythmic agents constitute a very heterogeneous group prone to various drug interactions and side-effects. Therefore, this article aims to summarise the most important facts and recent findings with regard to appropriate contemporary pharmacological therapy of atrial and ventricular arrhythmias in clinical practice. |
9,302 | [Prevention of sudden cardiac death]. | The problem of sudden cardiac death (SCD) is complex and many questions concerning the pathophysiologic mechanism are still unanswered. At present the only reliable way of recognizing high risk patients is by means of left ventricular dysfunction, measured as LV-EF<or=35%. The positive predictive accuracy for other non-invasive risk markers is too low. So far, antiarrhythmic drugs have failed to successfully prevent SCD. More than 25 years of clinical experience with the implantable defibrillator (ICD) with its continuous technical improvement has made the ICD the most effective weapon against SCD. Its effectiveness has been demonstrated in many prospective trials and the use of the ICD is fully enclosed within the current guidelines for the prevention of SCD. Guidelines do not, however, replace the physician's judgement and experience to correctly evaluate the patient's status. ICD therapy in the primary and secondary prevention of heart failure, which is often accompanied by a high risk of SCD is, however, not justified without guideline-adjusted therapy. |
9,303 | Microvascular blood flow during cardiopulmonary resuscitation is predictive of outcome. | There is growing evidence that microcirculatory blood flow is the ultimate determinant of the outcome in circulatory shock states. We therefore examined changes in the microcirculation accompanying the most severe form of circulatory failure, namely cardiac arrest and the effects of subsequent cardiopulmonary resuscitation. Ventricular fibrillation was electrically induced in nine pigs and untreated for 5min prior to beginning closed chest cardiac compression and attempting electrical defibrillation. Orthogonal polarization spectral imaging was utilized for visualization of the sublingual microcirculation at baseline, 0.5, 1, 3 and 5min after onset of ventricular fibrillation and at 1 and 5min after start of chest compression. Images were also obtained 1 and 5min after restoration of spontaneous circulation. Microvascular flow was graded from 0 (no flow) to 3 (normal flow). Aortic and right atrial pressures were measured and coronary perfusion pressure was computed continuously. Microcirculatory blood flow decreased to less than one-fourth within 0.5min after inducing ventricular fibrillation. Precordial compression partially restored microvascular flow in each animal. In animals that were successfully resuscitated, microvascular flow was significantly greater after 1 and 5min of chest compression than in animals with failed resuscitation attempts. Microvascular blood flow was highly correlated with coronary perfusion pressure (r=0.82, p<0.01). Microvascular blood flow in the sublingual mucosa is therefore closely related to coronary perfusion pressure during cardiopulmonary resuscitation and both are predictive of outcome. |
9,304 | Outcome of cardiopulmonary resuscitation in a 2300-bed hospital in a developing country. | To evaluate the outcome and quality of in-hospital cardiopulmonary resuscitation (CPR), and factors affecting the outcome.</AbstractText>A 2300-bed university hospital in Thailand.</AbstractText>A 1-year prospective audit according to the Utstein style.</AbstractText>A total of 639 cardiac arrests (370 male, 269 female, age 1 day-96 years, mean+/-S.D.=53.3+/-24.12 years) were included. Four hundred and thirty-three cardiac arrests (67.8%) occurred in non-monitored areas and 200 (31.3%) occurred in monitored areas. Five hundred and thirty-six cardiac arrests (84%) were witnessed. The majority of cardiac arrests occurred in medical patients (68.4%) and surgical patients (21.4%). The most common underlying causes of arrest were respiratory failure (24.7%) and septic shock (23.3%). Initial ECG rhythms were ventricular fibrillation 79 (12.4%), asystole 272 (42.6%) with pulseless electrical activity 225 (35.2%). Most patients received basic life support within 1 min (86.7%) and advanced life support (ALS) within 4 min (92.6%) but only 25% of patients received defibrillation within 3 min. Following resuscitation, 394 (61.7%) achieved restoration of spontaneous circulation and 44 patients (6.9%) survived to discharge. Only 162 post-arrest patients were treated in the critical care area. The initial survival rate was not associated with sex, age and time to ALS, but was significantly related to the monitored area.</AbstractText>In our setting, survival to discharge is 6.9%. Initial survival rate was strongly associated with being in a monitored area. Defibrillators and the critical care areas were insufficient.</AbstractText> |
9,305 | A randomized controlled trial of efficacy and ST change following use of the Welch-Allyn MRL PIC biphasic waveform versus damped sine monophasic waveform for external DC cardioversion. | Biphasic waveforms have similar or greater efficacy at cardioverting atrial and ventricular arrhythmias at lower energy levels than monophasic waveforms, and cause less ST depression following defibrillation of ventricular fibrillation. No studies have investigated this effect on ST change with atrial arrhythmias. We studied the efficacy of the Welch Allyn-MRL PIC biphasic defibrillator.</AbstractText>One hundred and thirty-nine patients undergoing elective DC cardioversion for atrial arrhythmias were randomised to cardioversion by monophasic (Hewlett Packard Codemaster XL; 100, 200, 300, 360 and 360J) or biphasic (Welch Allyn-MRL PIC; 70, 100, 150, 200 and 300J) defibrillator. We analysed success of cardioversion after 0 and 30min, cumulative energy, number of shocks and energy at successful cardioversion. The ST change in the recorded electrocardiogram was measured at 15s after all shocks using electronic callipers.</AbstractText>Immediately after cardioversion 59/68 (86.8%) of the monophasic group versus 56/60 (93.3%) of the biphasic group were in sinus rhythm. Of the monophasic group, 55/67 (82.1%) remained in sinus rhythm at 30min versus 53/58 (91.4%) of the biphasic group. These differences were not significant at 0min (P=0.35) or 30min (P=0.21). The biphasic group required significantly fewer shocks (P=0.006), less cumulative energy (P<0.0001) and required lower total energy for successful cardioversion (P<0.0001). Of the 102 patients with electrocardiogram recordings suitable for analysis, ST segment change was greater in the monophasic group (P=0.037).</AbstractText>The Welch Allyn-MRL biphasic waveform for DC cardioversion results in fewer shocks, with less cumulative energy delivered and less post shock ST change than with a Hewlett Packard Codemaster XL damped sine wave monophasic waveform.</AbstractText> |
9,306 | Colon ischaemia and necrosis as a complication of prolonged but successful CPR. | Survival after prolonged cardiopulmonary resuscitation (CPR) is often associated with neurological and other sequelae. We describe a patient who survived prolonged cardiac arrest due to ventricular fibrillation neurologically intact but suffered colon ischaemia and necrosis in the post-resuscitation period. Subtotal colectomy was performed. We wonder whether this complication was related to the use of vasopressin. |
9,307 | Adenosine A1 receptor antagonism hastens the decay in ventricular fibrillation waveform morphology during porcine cardiac arrest. | Endogenous adenosine (ADO) is known to be cardioprotective during acute myocardial ischemia. Coronary sinus ADO concentration has recently been shown to increase nearly 13-fold over baseline levels after 5 min of untreated ventricular fibrillation (VF). The role of ADO in VF has never been previously examined. The objective of this study was to determine the effect of ADO receptor antagonism, as measured by the scaling exponent (ScE), on the degeneration of VF over time during the circulatory phase of cardiac arrest.</AbstractText>A well-established swine model of prolonged VF arrest was used for this experiment. Eighteen domestic mixed-breed swine were assigned by block randomization to receive either DTI-0017 (5mg/kg), a potent ADO A(1) receptor antagonist or placebo in a double-blind fashion. The animals were instrumented under general anesthesia and acclimatized. The assigned solution was infused over 5 min. One minute after the infusion was completed, VF was induced with a 3s, 60 Hz, 100 mA transthoracic shock and left untreated. Lead II ECG was monitored continuously and recorded at 1000 samples/s. It was determined a priori that evaluation of the plots would be limited to a previously observed plateau phase historically occurring between 5 and 8 min corresponding to the circulatory phase of cardiac arrest. The scaling exponent values over this period were calculated for each of the 18 recordings using custom MATLAB routines. Using the Wald statistic to produce the Chi square distributions the null hypothesis, that there was no difference between the two groups, was tested. The Wald statistic calculation based on eight epochs from 300 to 475 s in placebo and DTI groups was significant to reject the null hypothesis of no difference in the groupxtime interaction at the 0.015 level (Chi square distribution for Wald=17.49, d.f.=7).</AbstractText>In this swine model, adenosine A(1) receptor antagonism accelerated the natural decay in the ECG VF waveform during the circulatory phase of cardiac arrest. Our findings would suggest that endogenous adenosine has cardioprotective effects during sudden cardiac arrest by slowing the time-dependent degeneration of VF.</AbstractText> |
9,308 | Predictors of stroke in high-risk patients after acute myocardial infarction: insights from the VALIANT Trial. | We sought to determine risk models for predicting early and late stroke in a large cohort of high-risk post-myocardial infarction (MI) patients.</AbstractText>We prospectively analysed data from 14 703 patients in the VALIANT trial with acute MI complicated by heart failure, left ventricular (LV) systolic dysfunction, or both. Patients were randomized 0.5-10 days after acute MI to valsartan, captopril, or their combination. We evaluated risk factors for early (<45 days) and late (>45 days) stroke by using multivariable Cox proportional hazards regression analyses with stepwise variable selection techniques applied to 92 pre-specified potential predictor variables. After randomization, 463 (3.2%) patients had fatal (n = 124) or non-fatal (n = 339) strokes, with 134 strokes occurring in the first 45 days. The strokes were classified as ischaemic (348), haemorrhagic (40), or of indeterminate cause (75). Estimated glomerular filtration rate and heart rate when in sinus rhythm were the most powerful predictors of early stroke (<45 days after MI), whereas diastolic blood pressure (DBP) >90 mmHg, prior stroke, and atrial fibrillation (AF) were the most powerful predictors of stroke overall. Ejection fraction and sex were not predictive of stroke in this cohort.</AbstractText>Among high-risk patients presenting with MI but without initial neurological symptoms, the risk of stroke 6 weeks thereafter is 0.94% (95% CI 0.78-1.09). Of the most powerful baseline predictors of stroke, DBP and AF are amenable to therapeutic interventions and thus merit special attention in these patients.</AbstractText> |
9,309 | Terminal arrhythmia in a patient with Mustard's operation. | In spite of significant improvements in outcome, adults surviving the Mustard procedure continue to be at risk of premature death, cardiac failure, and arrhythmias. Primary ventricular fibrillation as a cause of sudden death in these patients may not be uncommon, and implantation of a defibrillator should be considered, particularly if there is systemic ventricular dysfunction and pre-existing heart block. |
9,310 | [Effect of landiolol on heart rate control of atrial fibrillation in a patient with sick sinus syndrome under ventricular pacing]. | A 62-year-old man with an ventricular pacemaker for sick sinus syndrome received right shoulder arthroplasty. During the intraoperative discrepancy between heart rate and pulse rate, continuous infusion of low dose landiolol was useful to control his heart rate of atrial fibrillation. |
9,311 | Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest. | Cardiopulmonary resuscitation (CPR) and electrical defibrillation are the primary treatment options for ventricular fibrillation (VF). While recent studies have shown that providing CPR prior to defibrillation may improve outcomes, the effects of CPR quality remain unclear. Specifically, the clinical effects of compression depth and pauses in chest compression prior to defibrillation (pre-shock pauses) are unknown.</AbstractText>A prospective, multi-center, observational study of adult in-hospital and out-of-hospital cardiac resuscitations was conducted between March 2002 and December 2005. An investigational monitor/defibrillator equipped to measure compression characteristics during CPR was used.</AbstractText>Data were analyzed from 60 consecutive resuscitations in which a first shock was administered for VF. The primary outcome was first shock success defined as removal of VF for at least 5s following defibrillation. A logistic regression analysis demonstrated that successful defibrillation was associated with shorter pre-shock pauses (adjusted odds ratio 1.86 for every 5s decrease; 95% confidence interval 1.10-3.15) and higher mean compression depth during the 30s of CPR preceding the pre-shock pause (adjusted odds ratio 1.99 for every 5mm increase; 95% confidence interval 1.08-3.66).</AbstractText>The quality of CPR prior to defibrillation directly affects clinical outcomes. Specifically, longer pre-shock pauses and shallow chest compressions are associated with defibrillation failure. Strategies to correct these deficiencies should be developed and consideration should be made to replacing current-generation automated external defibrillators that require long pre-shock pauses for rhythm analysis.</AbstractText> |
9,312 | Ventricular fibrillation in a patient with prominent j wave in the inferior and lateral electrocardiographic leads after gastrostomy. | We describe the case of a 39-year-old man who experienced a ventricular fibrillation storm related to a prominent J wave in the inferior and lateral electrocardiographic leads on the day after gastrostomy. The J wave slowly decreased after amiodarone therapy (400 mg/day) was started, and ventricular fibrillation disappeared. |
9,313 | Spontaneous polymorphic ventricular tachycardia after administration of pilsicainide in a patient resuscitated from ventricular fibrillation. | We performed a pilsicainide challenge test in a 38-year-old man who was resuscitated from ventricular fibrillation without apparent baseline electrocardiogram (ECG) abnormality. His father had a history of ventricular fibrillation and his brother had multiple episodes of syncope. Pilsicainide (1 mg/kg) induced short coupled ventricular premature beats followed by repetitive polymorphic ventricular tachycardia without apparent J wave and ST elevation, and excessive changes in QRS duration and QT interval. An implantable cardioverter defibrillator was implanted. |
9,314 | The renin-angiotensin system: a therapeutic target in atrial fibrillation. | There is growing evidence to suggest a role for the renin-angiotensin system (RAS) in the pathogenesis of atrial fibrillation (AF). Experimental animal data suggest RAS-dependent mechanisms for the development of a structural and electrophysiologic substrate for AF. This is consistent with clinical data demonstrating the effectiveness of RAS blockade in preventing new-onset or recurrent AF in a variety of patient populations including patients with hypertension and left ventricular hypertrophy, congestive heart failure, and those undergoing electrical cardioversion for AF. This review summarizes experimental and clinical evidence to date relating to the role of RAS in the pathogenesis of AF, and the efficacy of its inhibition in managing this common arrhythmia. |
9,315 | Pulmonary vein vestibule ablation for the control of atrial fibrillation in patients with impaired left ventricular function. | Congestive heart failure (CHF) and atrial fibrillation (AF) are frequently linked, and when associated produce additive deleterious effects. In this prospective study, the effects of catheter ablation for AF in patients with impaired left ventricular (LV) function are presented.</AbstractText>Baseline data and clinical outcome have been prospectively collected in 105 consecutive patients who underwent pulmonary vein ablation for the control of AF. We evaluated 40 patients affected by LV dysfunction with ejection fraction (EF)<40% and compared them to the remaining 65 patients with normal ventricular function in terms of changes in LV function, maintenance of sinus rhythm, and quality of life during follow-up.</AbstractText>After a mean follow-up of 14+/-2 months, 87% of patients with impaired LV function and 92% of patients with normal ventricular function were in sinus rhythm, with or without antiarrhythmic therapy (P=NS). A significant improvement in LVEF and fractional shortening was documented in patients with CHF (33+/-2% vs 47+/-3%, and 19+/-4% vs 30+/-3%, P<0.01 for both comparisons). Evaluation of exercise capacity and quality of life documented better improvements in patients with CHF compared to patients without CHF.</AbstractText>Catheter ablation in patients with LV dysfunction is feasible, not associated with higher procedural complications, and provides a significant improvement in LV performance, symptoms, and quality of life during follow-up.</AbstractText> |
9,316 | Influence of drive cycle length on initiation of ventricular fibrillation during implantable cardioverter defibrillator threshold testing. | Programmed electrical stimulation of the heart as a method to induce tachyarrhythmias has been described since the 1960s. To date, no study has examined optimal drive cycle length in the induction of ventricular fibrillation (VF) during defibrillation threshold testing after implantable cardioverter-defibrillator placement. We hypothesized that longer drive cycle length, by means of the longer action potential duration, would promote intramyocardial phase 2 reentry and facilitate induction of VF.</AbstractText>Fifty consecutive implants were randomized in a prospective crossover format for this study. The group consisted of 40 men and 10 women, with each patient receiving either a 400 or 600 ms initial drive train prior to 1.2 J internal shock on the T wave with a goal to induce ventricular fibrillation. The timing of the T wave shock was determined by measuring the interval from the beginning of the QRS to the apex of the T wave in lead II. Successful inductions were defibrillated via the cardioverter defibrillator. Patients were then crossed over and the protocol repeated.</AbstractText>Twenty of 23 (87%) patients were successfully induced into VF in the initial 400 ms drive train arm whereas 22 of 27 (81%) were successfully induced in the 600 ms arm. Thus, a total of 44 (88%) patients were successfully induced at 400 ms, 41 (82%) patients were successfully induced at 600 ms, and 2 (4%) patients were not inducible at either cycle length, but were inducible with 50 Hz ventricular stimulation. However, no significant difference was noted between the two groups.</AbstractText>No investigation to date has questioned whether a relationship exists between drive cycle length and initiation of ventricular fibrillation. Our study addresses this question, though negative for difference between 400 and 600 ms drive trains. Further research into optimal strategies for inducing ventricular fibrillation will minimize patient sedation time and discomfort while undergoing defibrillator threshold testing.</AbstractText> |
9,317 | Persistent atrial fibrillation as a prognostic factor of outcome in patients with advanced heart failure. | Chronic heart failure (CHF) is associated with high morbidity and mortality and is diagnosed more and more frequently. Fifteen to 30% of patients with systolic CHF develop atrial fibrillation (AF).</AbstractText>To establish whether persistent AF was an independent predictor of mortality, and had a predictive value with respect to late clinical outcomes in patients with systolic CHF.</AbstractText>Analysis comprised 120 men with systolic CHF. In 35 (58%) patients CHF was the result of ischaemic heart disease and in 25 (42%)--idiopathic dilated cardiomyopathy (DCM). Presence or absence of AF was a criterion of patients' subsequent division into two subgroups. Sixty patients with AF were assigned to the AF group. The control group involved 60 individuals with CHF and sinus rhythm (SR) on enrollment. Mean follow-up time was 36 months.</AbstractText>Overall 59 (49%) patients died during 3-year follow-up, including 33 (56%) in the AF group. Deaths were noted more often in CHF patients with underlying ischaemic heart disease than DCM (66% vs 34%). This difference reached statistical significance in the AF group (72% vs 28%, p<0.001). Moreover, patients with AF more often complained of palpitations (p<0.01), had worse exercise capacity (p<0.01) as well as more frequently presented complex ventricular arrhythmia (p<0.01). The rate of hospital readmission was also higher (p<0.02). In univariate as well as multivariate analysis, AF was not found to be an independent predictor of mortality. Factors with a potential impact on adverse prognosis were concomitant complex ventricular arrhythmias (p=0.01), diabetes (0.04) and reduced exercise capacity (p<0.01).</AbstractText>Persistent AF is not an independent risk factor of death in patients with advanced systolic CHF. However, it has an unfavourable impact on functional status. Concomitant complex ventricular arrhythmias and reduced exercise capacity worsen prognosis in this group of patients.</AbstractText> |
9,318 | Cardiac arrhythmias and conduction disturbances in autoimmune rheumatic diseases. | Rhythm and conduction disturbances and sudden cardiac death (SCD) are important manifestations of cardiac involvement in autoimmune rheumatic diseases (ARDs). In patients with rheumatoid arthritis (RA), a major cause of SCD is atherosclerotic coronary artery disease, leading to acute coronary syndrome and ventricular arrhythmias. In systemic lupus erythematosus (SLE), sinus tachycardia, atrial fibrillation and atrial ectopic beats are the major cardiac arrhythmias. In some cases, sinus tachycardia may be the only manifestation of cardiac involvement. The most frequent cardiac rhythm disturbances in systemic sclerosis (SSc) are premature ventricular contractions (PVCs), often appearing as monomorphic, single PVCs, or rarely as bigeminy, trigeminy or pairs. Transient atrial fibrillation, flutter or paroxysmal supraventricular tachycardia are also described in 20-30% of SSc patients. Non-sustained ventricular tachycardia was described in 7-13%, while SCD is reported in 5-21% of unselected patients with SSc. The conduction disorders are more frequent in ARD than the cardiac arrhythmias. In RA, infiltration of the atrioventricular (AV) node can cause right bundle branch block in 35% of patients. AV block is rare in RA, and is usually complete. In SLE small vessel vasculitis, the infiltration of the sinus or AV nodes, or active myocarditis can lead to first-degree AV block in 34-70% of patients. In contrast to RA, conduction abnormalities may regress when the underlying disease is controlled. In neonatal lupus, 3% of infants whose mothers are antibody positive develop complete heart block. Conduction disturbances in SSc are due to fibrosis of sinoatrial node, presenting as abnormal ECG, bundle and fascicular blocks and occur in 25-75% of patients. |
9,319 | The progressive nature of atrial fibrillation: a rationale for early restoration and maintenance of sinus rhythm. | Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting young as well as elderly patients and presenting a major therapeutic challenge for clinical cardiologists. Recent research has elucidated the progressive nature of AF, including the structural and electrical remodelling that may become manifest if normal sinus rhythm is not restored, and the serious morbidities associated with long-term disease. The controversy over the merits of ventricular rate control vs. the restoration and maintenance of normal sinus rhythm in the treatment of AF has been explored in a number of large-scale, randomized clinical trials. The results of these trials suggest that whereas the two strategies may be equivalent for some patient populations, with both approaches requiring accompanying anticoagulation therapy, the restoration and maintenance of sinus rhythm provide important haemodynamic as well as subjective benefits not afforded by rate control. Although early intervention to limit the progression of this arrhythmia is hindered by the limitations of existing anti-arrhythmic therapies, it is nevertheless a critical goal. |
9,320 | Pathogenesis of cardiac conduction disorders in children genetic and histopathologic aspects. | Fetal dysrhythmias are usually transient. Abnormal fetal rates and rhythms during labor are "functional." Fetal dysrhythmias may be associated with congenital heart disease and fetal hydrops. Bradycardia is usually related to fetal distress; supraventricular tachycardia, atrial flutter, and atrial fibrillation may be associated with severe congestive heart failure. Ventricular fibrillation is rare in the fetus and infant and is usually associated with myocardial necrosis with perimembranous septal defect; the nonbranching atrioventricular (AV) bundle may have an aberrant position and result in cardiac arrhythmia. Wolff-Parkinson-White syndrome with conduction abnormalities and left ventricular hypertrophy (LVH) is due to an accessory pathway that bypasses the AV sulcus and results in faster conduction. Carnitine deficiency may be primary or secondary and may result in cardiac arrhythmia. Histiocytoid cardiomyopathy is characterized by cardiomegaly, incessant ventricular tachycardia, and frequently sudden death. Arrhythmogenic right ventricular dysplasia (ARVD) results in ventricular tachycardia and left bundle branch block. Noncompaction of the left ventricle predisposes to potentially fatal arrhythmias. Long Q-T syndromes (LQTS) are a heterogeneous group of disorders with many genetic mutations. Brugada syndrome is an autosomal dominant trait with right bundle branch block and ST elevation. Barth syndrome is an X-linked disorder with dilated cardiomyopathy, cyclic neutropenia and skeletal myopathy. Hypertrophic cardiomyopathy in infancy may be related to metabolic diseases, particularly glycogen storage diseases; the familial form predisposes to sudden death. Arrhythmias following cardiac surgery may occur after closure of a ventricular septal defect (VSD) or damage to the conduction system. |
9,321 | Therapeutic hypothermia for brain injury after cardiac arrest. | Morbidity and mortality in patients successfully resuscitated from cardiac arrest primarily depends on neurological outcome. Clinical trials of therapies directed toward reducing the extent of neuronal damage by means of pharmacological agents have been disappointing. To date, the only clinically effective tool for amelioration of brain damage by ischemia and reperfusion is mild to moderate induced hypothermia. The pathophysiology of global hypoxic-ischemic brain injury, the mechanisms by which hypothermia confers neuroprotection, and the encouraging beneficial effects of mild to moderate hypothermia in experimental studies and clinical trials are discussed. |
9,322 | [Ventricular tachycardia. Diagnostic spectrum and therapeutic measures]. | The origin of ventricular tachycardia lies in the ventricular tissue and includes a variety of symptoms such as monomorphic and polymorphic ventricular tachyarrhythmia (VT), ventricular flutter and ventricular fibrillation. Due to transitions of one form of VT to another, any form of VT incurs in principal the risk of cardiac failure. Apart from different electrophysiologic mechanisms such as reentry or triggered activity, any occurrence of VT has to be considered in an individual context: VT can be caused by structural heart disease such as coronary artery disease or dilative cardiomyopathy, or primary electrical disease such as long or short QT syndromes or can even occur without any detectable cause (idiopathic VT). Correct identification of the underlying cause of the arrhythmia is essential for the prognosis, differential therapy and long-term treatment of patients. |
9,323 | Raised plasma aldosterone and natriuretic peptides in atrial fibrillation. | During atrial fibrillation (AF), the renin-angiotensin-aldosterone system (RAAS) may be activated. In this study, our aim was to evaluate at a long-term follow-up visit the levels of plasma aldosterone and natriuretic peptides as markers of neurohormonal remodeling in patients with earlier, documented AF in relation to present heart rhythm, clinical data, and the left ventricular ejection fraction (LVEF). We hypothesized that increased levels of aldosterone and natriuretic peptides were significantly associated with present AF as markers of RAAS activation during the arrhythmia.</AbstractText>We studied 158 patients with earlier ECG-documented AF followed by restored sinus rhythm (SR) attending a follow-up visit 2.6 years (mean) after primary inclusion.</AbstractText>At follow-up, 93 patients had SR. Heart rhythm at follow-up visit (SR/AF), plasma aldosterone, plasma N-terminal pro Brain Natriuretic Peptide (Nt-proBNP), plasma N-terminal pro Atrial Natriuretic Peptide (Nt-proANP), LVEF, medication, and clinical characteristics were recorded. Standard linear multiple regression analysis including age, sex, weight, hypertension, congestive heart failure, ischemic heart disease, present AF at follow-up, total duration of AF disease, ongoing medication, and the LVEF as explanatory variables showed that only ongoing treatment with diuretics was significantly associated (likelihood ratio test, p = 0.0057) with a raised log-transformed plasma aldosterone, although present AF at follow-up was related to a high aldosterone level (p = 0.09). For the natriuretic peptides, present AF at follow-up (p < 0.0001), age (p < 0.0001), female gender (p = 0.0047), ischemic heart disease (p = 0.0154), and ongoing treatment with sotalol (p = 0.0003) were all independently associated with high log-transformed plasma Nt-proANP. Likewise, present AF at follow-up (p = 0.0008) as well as age (p < 0.0001) were associated with high log-transformed plasma Nt-proBNP.</AbstractText>In patients with earlier AF, AF at long-term follow-up visit was independently associated with raised levels of Nt-proANP and Nt-proBNP and to some extent with plasma aldosterone indicating neurohormonal activation during arrhythmia.</AbstractText>Copyright 2007 S. Karger AG, Basel.</CopyrightInformation> |
9,324 | Regression of electrocardiographic left ventricular hypertrophy and decreased incidence of new-onset atrial fibrillation in patients with hypertension. | Atrial fibrillation (AF) is associated with increased risk of mortality and cardiovascular events, particularly stroke, making prevention of new-onset AF a clinical priority. Although the presence and severity of electrocardiographic left ventricular hypertrophy (LVH) appear to predict development of AF, whether regression of electrocardiographic LVH is associated with a decreased incidence of AF is unclear.</AbstractText>To test the hypothesis that in-treatment regression or continued absence of electrocardiographic LVH during antihypertensive therapy is associated with a decreased incidence of AF, independent of blood pressure and treatment modality.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PARTICIPANTS" NlmCategory="METHODS">Double-blind, randomized, parallel-group study conducted in 1995-2001 among 8831 men and women with hypertension, aged 55-80 years (median, 67 years), with electrocardiographic LVH by Cornell voltage-duration product or Sokolow-Lyon voltage, with no history of AF, without AF on the baseline electrocardiogram, and enrolled in the Losartan Intervention for Endpoint Reduction in Hypertension Study.</AbstractText>Losartan- or atenolol-based treatment regimens, with follow-up assessments at 6 months and then yearly until death or study end.</AbstractText>New-onset AF in relation to electrocardiographic LVH determined at baseline and subsequently. Electrocardiographic LVH was measured using sex-adjusted Cornell product criteria ({R(aVL) + S(V3) [+ 6 mm in women]} x QRS duration).</AbstractText>After a mean (SD) follow-up of 4.7 (1.1) years, new-onset AF occurred in 290 patients with in-treatment regression or continued absence of Cornell product LVH for a rate of 14.9 per 1000 patient-years and in 411 patients with in-treatment persistence or development of LVH by Cornell product criteria for a rate of 19.0 per 1000 patient-years. In time-dependent Cox analyses adjusted for treatment effects, baseline differences in risk factors for AF, baseline and in-treatment blood pressure, and baseline severity of electrocardiographic LVH, lower in-treatment Cornell product LVH treated as a time-varying covariate was associated with a 12.4% lower rate of new-onset AF (adjusted hazard ratio [HR], 0.88; 95% CI, 0.80-0.97; P = .007) for every 1050 mm x msec (per 1-SD) lower Cornell product, with persistence of the benefit of losartan vs atenolol therapy on developing AF (HR, 0.83; 95% CI, 0.71-0.97; P = .01).</AbstractText>Lower Cornell product electrocardiographic LVH during antihypertensive therapy is associated with a lower likelihood of new-onset AF, independent of blood pressure lowering and treatment modality in essential hypertension. These findings suggest that antihypertensive therapy targeted at regression or prevention of electrocardiographic LVH may reduce the incidence of new-onset AF.</AbstractText> |
9,325 | Effects of chronic trimetazidine treatment on myocardial preconditioning in anesthetized rats. | Trimetazidine is a widely used anti-ischemic agent, but effects of its chronic treatment on myocardial preconditioning in anesthetized animals have not been investigated. The aim of this study was to examine the effects of 15-day treatment of trimetazidine on ischemic preconditioning and carbachol-induced preconditioning in anesthetized rats. Ischemic preconditioning, induced by 5 min of coronary artery occlusion and 5 min of reperfusion, significantly decreased the total number of ventricular ectopic beats, the incidence of ventricular tachycardia and abolished the occurrence of ventricular fibrillation (VF) during 30 min of ischemia. Trimetazidine (10 mg/kg/day, i.p. for 15 days and 10 mg/kg, i.v.) itself attenuated these arrhythmia parameters with no marked effect on hemodynamic effects. In the presence of trimetazidine, anti-arrhythmic effects of ischemic preconditioning were present. Carbachol infusion induced preconditioning with a marked depression of mean arterial blood pressure, heart rate and the total number of ventricular ectopic beats. No VF was observed in carbachol-induced preconditioning. The marked reductions in arrhythmia parameters that induced carbachol-induced preconditioning were also preserved in the presence of trimetazidine. Arrhythmia scores and myocardial infarct size were reduced significantly with ischemic preconditioning or carbachol-induced preconditioning and were not modified by trimetazidine. Lactate and malondialdehyde levels were suppressed significantly with preconditioning or trimetazidine + preconditioning groups. These results show that chronic treatment of trimetazidine protects the heart against ischemia-induced arrhythmias, reduces myocardial infarct size, plasma lactate and malondialdehyde levels, and preserves the effects of ischemic and pharmacological preconditioning in anesthetized rats. |
9,326 | Acute myocardial infarction in a young adult: a case report and literature review. | Sudden cardiac death related to sports in young patients can have many causes. Hypertrophic cardiomyopathy, congenital coronary abnormalities, and myocarditis make up about half of the causes of sudden cardiac death after sports. Screening for all athletes is important to prevent such episodes. This involves yearly examinations including clinical examinations, stress echocardiograms, echocardiography, and laboratory investigations. Also, behavioral follow up should be addressed, as cocaine administration and doping can both lead to cardiac problems and sudden cardiac death after sports. We present a case of a 17-year-old boy who collapsed after an ice hockey competition as a result of an acute myocardial infarction, which was first represented by ventricular fibrillation. We also review the main causes of sudden cardiac death in such young athletes and the main investigations that have to be performed to reach the proper diagnosis and etiology of the condition. |
9,327 | Heart disease and aging. | CAD is the most common cause of death in older persons and was present in 43% of 1,160 men and in 41% of 2,464 women, mean age 81 years. Hypertension was present in 60% of these older women and in 57% of these older men. The prevalence of valvular aortic stenosis, aortic regurgitation, mitral regurgitation, and MAC increases with age in older men and in older women. The prevalence and incidence of CHF increase with age. CHF is the most common cause of hospitalization in persons aged 65 years and older. The prevalence of normal LV ejection fraction associated with CHF increases with age and is higher in older women than in older men. The prevalence of chronic atrial fibrillation increases with age and was present in 16% of 1,160 older men and in 13% of 2,464 older women. Atrial fibrillation is an independent predictor of new coronary events and thromboembolic stroke in older persons. Older persons who have unexplained syncope should have 24-hour ambulatory electrocardiograms to determine whether pauses of longer than 3 seconds are present that require permanent pacemaker implantation. |
9,328 | CPU86017: a novel Class III antiarrhythmic agent with multiple actions at ion channels. | CPU86017 is a novel Class III antiarrhythmic agent derived from berberine and with an improved pharmacological profile, solubility and bioavailability. It is active in suppressing arrhythmias in several animal models. The ED(50) of CPU86017 for suppressing ischemia/reperfusion arrhythmias in rats was 0.22 mg/kg against 2.23 mg/kg for lidocaine. CPU86017 is about 10-fold more potent than lidocaine. It blocks I(K(R.tail)), I(K(S)), and I(Ca(L)) currents with IC(50) values of 25, 14.4, and 11.5 microM, respectively. The plasma t(1/2) of CPU86017, i.v. bolus, in rabbits and dogs is approximately 90 min. The effective plasma levels of CPU86017 in rabbits required to delay the appearance of oubain-induced ventricular arrhythmias is in the range of 0.13-0.31 microg/mL. Higher levels of the drug are required to eliminate ventricular arrhythmias produced by two-stage ligation of the coronary artery in anesthetized dogs. Drug levels in myocardium are much higher than in plasma. CPU80617 has an antioxidant effect that is likely to contribute to its antiarrhythmic activity. The abnormal expression of the ryanodine receptor type 2 (RyR2) and of FKBP12.6 is reduced by CPU80617 during its ventricular tachyarrhythmia-suppressing action. CPU86017 appears to be a promising antiarrhythmic agent with a cardioprotective action. It can be expected to protect from malignant arrhythmias and sudden cardiac death by suppressing molecular events caused by channelopathies. |
9,329 | Effect of electroacupuncture on reperfusion ventricular arrhythmia in rat. | Protective effect and mechanism of electroacupuncture (EA) on acute reperfusion ventricular arrhthmia was investigated. Ventricular arrhythmia was induced by occlusion of the proximal left anterior descend (LAD) branch of coronary artery for 5 min and followed with 15 min reperfusion. EA on acupoint "Neiguan", "Jianshi" was performed at 30 min before ligation and continued another 5 min during ischemia. Isoprenaline (20, 30 and 50 microg/kg) or atropine (1 mg/ kg) was intravenously injected at 5 min before ischemia. The results showed that EA significantly decreased the incidence of ischemia/reperfusion (I/R) induced ventricular tachycardia (VT), ventricular fibrillation (VF) and mortality as compared to I/R group. Atropine partially suppressed the EA's effect of antiarrhythmia; Isoprenaline increased the incidence and severity of reperfusion arrhythmia, which was inhibited by EA, but this inhibition of EA was blocked with increasing dose of isoprenaline. The results indicated that EA treatment could prevent the occurrence of reperfusion ventricular arrhythmia in rats with myocardial ischemia, and its mechanism might be related to the regulation of EA on the beta-adrenoceptors and M-cholinergic receptor activation in myocardium. |
9,330 | Tako-tsubo cardiomyopathy: reversible heart failure with favorable outcome in patients with intracerebral hemorrhage. Case report. | In patients with intracerebal hemorrhage, cardiac dysfunction is a common phenomenon. Tako-tsubo cardiomyopathy is characterized by complete reversibility and therefore may constitute an entity with a favorable outcome. In this case report the authors describe a previously healthy 23-year-old man with no history of cardiac disease who suffered a severe fourth ventricular hemorrhage due to an angioma of the vermis cerebelli. After emergency surgery, progressive tachycardia, fibrillation, and electromechanical decoupling developed in the patient. An echocardiogram revealed left ventricular apical akinesia and basal hyperkinesis characteristic of tako-tsubo cardiomyopathy. One week after admission, cardiac function was normal. Tako-tsubo cardiomyopathy differs from common cardiac dysfunction in its reversible nature. This characteristic must be taken into consideration when treating patients with intracerebral hemorrhage to avoid misclassification of the disease. |
9,331 | Assessment of factors affecting plasma BNP levels in patients with chronic atrial fibrillation and preserved left ventricular systolic function. | Several studies have reported that plasma brain natriuretic peptide (BNP) levels are increased in patients with chronic atrial fibrillation (AF). The objective of this study was to assess the factors influencing plasma BNP levels in patients with chronic AF and preserved left ventricular (LV) systolic function.</AbstractText>Transthoracic echocardiography was performed in 104 patients (48 men, 56 women; mean age, 63.9+/-10.7 years) with chronic AF. At the same time, plasma BNP levels were measured with a Triage kit (Biosite, San Diego, CA).</AbstractText>Women, long duration of AF, and hypertension were more prevalent in the highest quartile group of BNP levels than in the lowest quartile of BNP. Significant correlations were observed between plasma BNP levels and the following: mitral E velocity (r=0.343), mitral annular E' velocity (r=-0.402), ratio of mitral E velocity and mitral annular E' velocity (r=0.487), left atrial(LA) size (r=0.653), LA volume index (r=0.775), right atrial (RA) volume index (r=0.563), maximal velocity (V(max)) of mitral regurgitation (MR) (r=0.448), tricuspid regurgitation (TR) V(max) (r=0.532) and LV mass index (r=0.581). In stepwise multiple linear regression analysis, LA volume index (beta=0.326, p<0.001), LV mass index (beta=0.395, p<0.001) and duration of AF (beta=0.492, p<0.001) independently predicted plasma BNP levels in the study subjects. The patients with increased LA volume index exhibited a longer duration of AF, larger RA volume index and LV mass index, higher MR V(max), TR V(max) and plasma BNP level.</AbstractText>LA volume index, LV mass index and duration of AF are independent predictors of plasma BNP levels in patients with chronic AF and preserved LV systolic function.</AbstractText> |
9,332 | Enteroviral infections in children with malignant disease: a 5-year study in a single institution. | The clinical presentation, severity and outcome of enteroviral infections in children with malignancy were studied.</AbstractText>All cases of enteroviral infections in a University Pediatric Hematology-Oncology Unit were assessed, during a 5-year period. RT-PCR, immunohistochemistry and indirect immunofluorescence assay were performed to document the enteroviral infection and the type of virus.</AbstractText>Fifty-five children had documented enteroviral infection among 104 patients evaluated for possible enteroviral infection. Severe manifestations occurred in 11/55 (20%) patients, such as encephalitis 5/55, cardiac involvement 3/55 (1/55 myocarditis, 1/55 dilated cardiomyopathy, 1/55 ventricular fibrillation) and infection associated hemophagocytic syndrome 3/55. Children with lymphoid malignancy had increased incidence of enteroviral infections (87%) compared to children with solid tumors (13%). All patients received supportive care, intravenous immunoglobulin (IVIG) (30/55 low dose 400 mg/kg or 25/55 high dose 2 gr/kg) and/or pleconaril (2/55). All patients who received high dose of IVIG developed early negative viral load. However, 4 of them succumbed. Infection related fatality rate was 14.5% (N=8).</AbstractText>Enteroviruses caused more severe and lethal manifestations especially in children with lymphoid malignancy. The administration of high dose of IVIG was beneficial in viremia. Thus, the early therapeutic intervention with high dose of IVIG may improve the outcome.</AbstractText> |
9,333 | Postmortem redistribution of two antipsychotic drugs, haloperidol and thioridazine, in the rat. | Antipsychotic drugs may be associated with arrhythmia, ventricular fibrillation, or torsades de pointes, which can result in sudden death. These drugs could therefore be found in postmortem toxicological analyses of autopsy specimens following unexplained sudden death. The drug concentrations in tissues and body fluids change between the death and postmortem specimens collection because of postmortem redistribution. For this reason, it is often difficult to interpret the postmortem analysis. The aim of this study was to investigate postmortem redistribution of the two cardiotoxic antipsychotic drugs, haloperidol and thioridazine, in order to interpret the postmortem analysis. We have chosen the rat as an animal model. The rats received 1 mg/kg of haloperidol and 5 mg/kg of thioridazine by intraperitoneal injection. They were sacrificed and left at room temperature for 2, 6, 12, 24, or 48 h, at which times blood and tissue samples were taken. The drug analyses in tissues and blood were done using a liquid chromatography- tandem mass spectrometry method. Our results show that there is a redistribution of the two drugs from the lung to the cardiac blood. The concentration of the antipsychotic drugs in the lung decreased rapidly, whereas in the cardiac blood, this concentration increased within the first 2 h postmortem. By 48 h after death, the concentrations of the antipsychotic drugs were about twice as high as the initial concentrations in the cardiac blood. For the lungs, a decrease of 50% was observed between 0 and 48 h. Only myocardium and muscle concentrations did not change with the postmortem delay. |
9,334 | Myocardial dysfunction in polymyositis. | Myocardial involvement in polymyositis is occasionally suspected, but symptomatic cardiac dysfunction is rarely reported. Described in the present report is a 48-year-old woman with a two-year history of polymyositis who suddenly developed near fatal ventricular arrhythmia, and a 56-year-old man with a relapsing polymyositis who developed severe systolic dysfunction. These two cases emphasize the importance of systematic cardiac evaluation when the diagnosis of polymyositis is initially made and the necessity of re-evaluating cardiac function, even in the presence of clinical remission and normalization of creatine phosphokinase with treatment.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Sénéchal</LastName><ForeName>Mario</ForeName><Initials>M</Initials><AffiliationInfo><Affiliation>Quebec Heart Institute, Laval Hospital Research Center Ste-Foy, Quebec. duboissenechal@videotron.ca</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Crête</LastName><ForeName>Martin</ForeName><Initials>M</Initials></Author><Author ValidYN="Y"><LastName>Couture</LastName><ForeName>Christian</ForeName><Initials>C</Initials></Author><Author ValidYN="Y"><LastName>Poirier</LastName><ForeName>Poul</ForeName><Initials>P</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>England</Country><MedlineTA>Can J Cardiol</MedlineTA><NlmUniqueID>8510280</NlmUniqueID><ISSNLinking>0828-282X</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D009202" MajorTopicYN="N">Cardiomyopathies</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="Y">etiology</QualifierName><QualifierName UI="Q000503" MajorTopicYN="Y">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004719" MajorTopicYN="N">Endomyocardial Fibrosis</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D005260" MajorTopicYN="N">Female</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008297" MajorTopicYN="N">Male</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008875" MajorTopicYN="N">Middle Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D017285" MajorTopicYN="N">Polymyositis</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="Y">complications</QualifierName><QualifierName UI="Q000503" MajorTopicYN="Y">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D013318" MajorTopicYN="N">Stroke Volume</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D018487" MajorTopicYN="N">Ventricular Dysfunction, Left</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D014693" MajorTopicYN="N">Ventricular Fibrillation</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading></MeshHeadingList><OtherAbstract Type="Publisher" Language="fre">Dans la polymyosite, on soupçonne parfois une atteinte myocardique, mais les cas de dysfonction cardiaque symptomatique sont rares. Le présent rapport décrit le cas d’une femme de 48 ans présentant des antécédents de polymyosite depuis deux ans qui a subitement présenté une arythmie ventriculaire quasi fatale et celui d’un homme de 56 ans victime d’une rechute de sa polymyosite qui a développé une dysfonction systolique sévère. Ces deux cas rappellent l’importance d’une évaluation cardiaque systématique lorsqu’un diagnostic de polymyosite a déjà été posé et la nécessité de réévaluer la fonction cardiaque, même si le patient semble en rémission clinique et même si un traitement a permis de normaliser les taux de créatine phosphokinase. |
9,335 | Is there a role for antiarrhythmic drugs in patients with implantable defibrillators? | With remarkable advancement in technology and clinical research, implantable cardioverter defibrillators (ICDs) have replaced antiarrhythmic drugs as the preferred modality for both primary and secondary prevention of arrhythmic deaths. However, concomitant use of antiarrhythmics in patients with ICDs remains common, often for prevention or reduction of appropriate and inappropriate shocks caused by ventricular and supraventricular arrhythmias, respectively. The role of empiric antiarrhythmic therapy in this patient population remains less clearly defined, with conflicting information from various small randomized trials. Use of antiarrhythmic drugs in the ICD patient population not only can cause potentially serious side effects but can also interact or interfere with the ICD device function. In addition, the effect on survival in patients with ICDs is not well characterized. Given the many potential side effects, drug-device interactions, unclear survival effect, and lack of convincing clinical data supporting its use, empiric antiarrhythmic therapy in the ICD patient population cannot be recommended at this time. |
9,336 | Amiodarone: a multifaceted antiarrhythmic drug. | Synthesized as an antianginal compound 40 years ago, amiodarone has emerged as a uniquely effective antiarrhythmic compound in recent years. It has numerous properties, the most prominent being the ability to lengthen repolarization in the atria and ventricles associated with bradycardia without the significant potential for torsades de pointes. Amiodarone effectively controls a wide spectrum of atrial and ventricular antiarrhythmic disorders, but its limiting side effects, such as thyroid dysfunction, pulmonary fibrosis, and dermatologic changes, may limit its long-term use in some patients. What aspects of the multiplicity of the properties of amiodarone are relevant to its unusual efficacy is not known. Deiodination and other structural changes in the amiodarone molecule have has led to a the loss of thyroid and pulmonary effects in the resulting derivative, dronedarone, which is in advanced clinical development. |
9,337 | Cardiac resynchronization therapy: role of patient selection. | Cardiac resynchronization therapy (CRT) is a well-accepted and effective therapy for treating patients with a wide QRS complex, significant left ventricular systolic dysfunction, and symptoms of advanced heart failure. However, approximately 25% to 30% of patients fail to respond to this therapy. Most large studies have used electrical dyssynchrony (wide QRS) as a main entrance criterion. Emerging data suggest that mechanical dyssynchrony may be a more important factor in selecting appropriate candidates for CRT. New echocardiographic (ECHO) imaging modalities such as tissue Doppler imaging, three-dimensional ECHO, and speckle tracking ECHO are able to quantify left ventricular mechanical dyssynchrony. These techniques are currently being used to assist in the selection of patients for CRT. Recently published and ongoing studies are addressing the use of CRT in patients who do not meet the standard criteria, such as patients with atrial fibrillation, mild to moderate heart failure, narrow QRS complex, and acute myocardial infarction. |
9,338 | New indications for implantable defibrillator therapy. | Implantable cardioverter defibrillator (ICD) therapy has been extensively evaluated in patients at high risk of sudden cardiac death. Most recently, the Sudden Cardiac Death in Heart Failure Trial found that patients with moderate symptoms of congestive heart failure, whether due to an ischemic or a nonischemic cause, have reduced mortality compared with patients treated only with conventional medical therapy for heart failure. The results of this trial confirm those of earlier trials finding a benefit of ICD therapy in patients with coronary artery disease and reduced left ventricular systolic function, and extend the indications for ICD therapy to those without coronary artery disease. |
9,339 | Applications, complications, and outcomes of transvenous pacemaker implantation in 105 dogs (1997-2002). | We reviewed the indications for age and breeds of dogs who received transvenous endocardial artificial pacemaker (AP) implantation (n = 105) and complications and survival thereafter at a single institution over a 6-year period. A third-degree atrioventricular (AV) block (59%) and sick sinus syndrome (SSS; 27%) were the most common indications, along with a high-grade second-degree AV block (9%) and atrial standstill (5%). The most common breeds identified were Labrador Retriever (n = 16; 11 with a third-degree AV block), American Cocker Spaniel (n = 14; 10 with SSS), and Miniature Schnauzer (n = 13; all with SSS). Common presenting complaints were syncope (n = 66) and exercise intolerance or lethargy (n = 25). Half of the dogs (n = 52) had a history of acute onset of clinical signs (<2 weeks). Mean survival time for the 60 dogs who died during the study period was 2.2 years (range, 0.1-5.8 years). Major complications occurred in 13% of dogs and included lead displacement (n = 7), sensing problems that led to syncope (n = 3), infection at the pacemaker site (n = 1), bleeding (n = 1), and ventricular fibrillation during implantation (n = 1; successfully defibrillated). Minor complications occurred in 11 dogs (11%). The success rate of transvenous AP implantation was comparatively high (all dogs survived the first 48 hours), and the complication rate was comparatively low when compared with a previous multicenter study, most likely because of how commonly the procedure was performed and supervisory experience. |
9,340 | How sudden is sudden cardiac death? | Out-of-hospital sudden cardiac death (SCD) is a frequent cause of death. Survival rates remain low despite increasing efforts in medical care. Better understanding of the circumstances of SCD could be helpful in developing preventive measures and facilitating proper reactions to such a pending event.</AbstractText>Information on cases of out-of-hospital SCD was collected in the Berlin, Germany, emergency medical system via a questionnaire. Bystander interviews were performed by the emergency physician on scene immediately after declaration of death or return of circulation. Of 5831 rescue missions, 406 involved patients with presumed cardiac arrest. Sixty-six percent had a known cardiac disease. In 72%, the arrest occurred at home, and in 67%, it occurred in the presence of an eyewitness. Information on symptoms immediately preceding the arrest was available in 80% (n = 323) of all 406 patients and in 274 of those with witnessed arrest. Symptoms were identical in the 2 groups. Typical angina was present for a median of 120 minutes in 25% of the 274 patients with witnessed arrest and in 33% with a symptom duration of less than 1 hour.</AbstractText>SCD occurs most often at home in the presence of relatives and after a longer period of typical warning symptoms. Although the much-hailed use of public access defibrillation is supported by several studies, the present results raise the question of whether educational measures and targeted educational programs tailored for patients at risk and their relatives should have a higher priority.</AbstractText> |
9,341 | Risk factors for primary ventricular fibrillation during acute myocardial infarction: a systematic review and meta-analysis. | To evaluate potential risk factors for primary ventricular fibrillation (PVF) during acute myocardial infarction (AMI) by a systematic review and meta-analyses.</AbstractText>We searched PubMed for English articles on 'humans' published between 1964 and January 2006 using a validated combination of MESH terms. Twenty-one cohort studies describing 57 158 patients with AMI were analysed. Patients with validated PVF (n=2316) were characterized by an earlier admission (weighted mean difference -2.62 h), male gender [odds ratio (OR 1.27)], smoking (OR 1.26), absence of history of angina (OR for history of angina 0.84), lower heart rate at admission (weighted mean difference -4.02 b.p.m.), ST-segment elevation on admission ECG (OR 3.35), AV conduction block before PVF (OR 2.02), and lower serum potassium at admission (weighted mean difference -0.27 meq/L). Patients with validated PVF developed a larger enzymatic infarct size (standardized mean difference 0.74, P<0.00001). PVF was not associated with a history of myocardial infarction or hypertension.</AbstractText>Patients who developed a validated PVF presented with characteristics of both abrupt coronary occlusion and early hospital admission. This review provides no evidence for risk factors for PVF other than ST-elevation and time from onset of symptoms. To find new risk factors, studies should compare validated PVF patients with non-PVF patients who have no signs of heart failure and comparable time delay between onset of symptoms and medical attendance.</AbstractText> |
9,342 | A prospective study on spontaneous fluctuations between diagnostic and non-diagnostic ECGs in Brugada syndrome: implications for correct phenotyping and risk stratification. | Fluctuations between the diagnostic ECG pattern and non-diagnostic ECGs in patients with Brugada syndrome are known, but systematic studies are lacking. The purpose of this study was to prospectively evaluate the spontaneous ECG changes between diagnostic and non-diagnostic ECG patterns in patients diagnosed with Brugada syndrome.</AbstractText>In 43 patients with Brugada syndrome (27 males; mean age 45+/-11 years), 310 resting ECGs were obtained during a median follow-up of 17.7 months. The ECGs were analysed for the presence of coved type, saddle-back type or no, respectively unspecific, changes. A coved-type ECG pattern with more than 2 mm ST-segment elevation in at least two right precordial leads was defined as diagnostic. The patients were compared for different clinical characteristics with respect to the pattern of fluctuations. Out of a total of 310 ECGs, 102 (33%) revealed a coved type, 91 (29%) a saddle-back type, and 117 (38%) a normal ECG. Fifteen patients (35%) initially presented with a diagnostic coved-type ECG. Fourteen patients (33%) with an initially coved-type ECG exhibited intermittently non-diagnostic ECGs during follow-up. Only one patient (2%) presented constantly with a coved-type ECG. Out of 28 patients (65%) with an initially non-diagnostic ECG, eight (19%) patients developed a diagnostic coved-type ECG during follow-up. Twenty patients (47%) revealed a coved-type ECG during ajmaline challenge, but never had a baseline coved-type ECG recorded. No significant differences were found in gender and clinical characteristics among patients with or without fluctuations between diagnostic and non-diagnostic basal ECGs. The rate of inducible ventricular fibrillation was significantly higher in patients with more than 50% coved-type ECGs than in patients with less than 50% diagnostic ECGs.</AbstractText>The prevalence of fluctuations between diagnostic and non-diagnostic ECGs in patients with Brugada syndrome is high and may have an implication on the correct phenotyping and on the risk stratification in patients with Brugada syndrome without aborted sudden cardiac death. For correct phenotyping and risk stratification, repetitive ECG recordings seem to be mandatory.</AbstractText> |
9,343 | The diagnostic utility of N-terminal pro-B-type natriuretic peptide for the detection of major structural heart disease in patients with atrial fibrillation. | To assess the role of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in the diagnosis of major structural heart disease (MSHD) in patients with atrial fibrillation (AF) compared with those with sinus rhythm (SR) using receiver operator characteristic (ROC) analysis. NT-proBNP is elevated in MSHD and heart failure (HF). AF, a common finding in HF and MSHD, is also associated with raised plasma NT-proBNP. As a result, the utility of NT-proBNP for predicting MSHD may be reduced.</AbstractText>One thousand four hundred and seventy-six patients underwent assessment at a single centre, performed without the knowledge of NT-proBNP levels. MSHD included left ventricular (LV) systolic and diastolic dysfunctions, left-sided valvular disease, right heart disease (including pulmonary hypertension) and severe LV hypertrophy. One hundred and fifty-five patients were excluded due to renal impairment, atrial flutter, or a pacemaker. Seven hundred and ninety-three patients were diagnosed with MSHD. Median NT-proBNP concentrations for patients with MSHD were 960 (IQR 359-2625) pg/mL and 2491 (1443-4368) pg/mL for SR (n = 591) and AF (n = 202), respectively (P < 0.001). Patients without MSHD had NT-proBNP levels of 179 (90-401) pg/mL and 1000 (659-1760) pg/mL for SR (n = 454) and AF (n = 74), respectively (P < 0.001). The area under the ROC curve for NT-proBNP to detect MSHD was 0.79 for SR (95% CI 0.77-0.82) and 0.78 for AF (95% CI 0.72-0.84). NT-proBNP cut-off levels necessary to achieve a 1 in 100 false negative rate were 27.5 (7.5-30.5) pg/ml and 524 (253-662) pg/ml for SR and AF, respectively.</AbstractText>NT-proBNP performs as well in patients with SR as in those with AF. However, significantly higher cut-off levels are required for patients with AF to achieve similar levels of diagnostic specificity.</AbstractText> |
9,344 | [Predictors of in-hospital lethality in patients with advanced heart failure]. | Describe the clinical characteristics and identify potential risk factors for in-hospital lethality in patients with decompensated heart failure admitted to an intensive care unit.</AbstractText>Decompensated heart failure patients consecutively admitted to an intensive care unit between June 2001 and December 2003 were selected and followed during hospitalization until discharge or death. Clinical characteristics at admission were recorded and evaluated as independent risk predictors for in-hospital mortality by multiple logistic regression analysis.</AbstractText>A total of 299 patients (69+/-13 years of age and 54% men) were enrolled. Coronary artery disease was the main cause of heart failure in 49% of the cases. Diabetes mellitus and systemic arterial hypertension occurred in 37.5% and 78% of the patients, respectively. At admission, 22% of them had atrial fibrillation, 21.5% had renal dysfunction, and 48% anemia (16.5% with severe anemia). Severe systolic dysfunction (left ventricular ejection fraction <30%) affected 44% of the patients. In-hospital mortality was 17.4%. After the multivariate analysis had been performed, previous history of stroke, atrial fibrillation, renal failure, age > 70 years, and hyponatremia were independently associated with in-hospital mortality.</AbstractText>Patients admitted to an intensive care unit due to decompensated heart failure have high in-hospital lethality. In this study, variables recorded at admission, such as previous stroke, atrial fibrillation, hyponatremia, renal failure, and age > 70 years were predictors of in-hospital lethality.</AbstractText> |
9,345 | Prognostic value of preoperative atrial fibrillation in patients with aortic stenosis and low ejection fraction having aortic valve replacement. | Aortic valve replacement in severe aortic stenosis (AS) with a low left ventricular ejection fraction (EF) is associated with high perioperative mortality. The aim of this study was to assess the prognostic value of preoperative atrial fibrillation (AF) in patients with AS and low EFs who undergo aortic valve replacement. Eighty-three consecutive patients with severe AS (area <1 cm2) and low EFs (< or =35%) were prospectively included. Perioperative mortality was 12%. Twenty-nine patients (35%) had preexisting paroxysmal or permanent AF. Perioperative mortality was higher in the AF group than in the non-AF group (24% vs 5.5%, p = 0.03). Preoperative AF was identified as an independent predictor of perioperative mortality (odds ratio 7.5, 95% confidence interval 1.19 to 47.06, p = 0.03). Five-year overall survival was lower in the AF group than in the non-AF group (47% vs 77%, p = 0.0017). Associated multivessel coronary artery disease and preoperative AF were identified as 2 independent predictors of overall mortality. In conclusion, in patients with AS with low left ventricular EFs, preoperative AF is associated with higher operative risk and lower postoperative survival. The presence of AF in patients with severe AS and low EFs should be taken into account for operative risk stratification, along with low pressure gradient and associated multivessel coronary artery disease. |
9,346 | Ventricular fibrillation induced by stretch pulse: implications for sudden death due to commotio cordis. | Nonpenetrating chest wall impact (commotio cordis) may lead to sudden cardiac death due to the acute initiation of ventricular fibrillation (VF). VF may result from sudden stretch during a vulnerable window, which is determined by repolarization inhomogeneity.</AbstractText>We examined action potential morphologies and VF inducibility in response to sudden myocardial stretch in the left ventricle (LV). In six Langendorff perfused rabbit hearts, the LV was instrumented with a fluid-filled balloon. Increasing volume and pressure pulses were applied at different times of the cardiac cycle. Monophasic action potentials (MAPs) were recorded simultaneously from five LV epicardial sites. Inter-site dispersion of repolarization was calculated in the time and voltage domains.</AbstractText>Sudden balloon inflation induced VF when pressure pulses of 208-289 mmHg were applied within a window of 35-88 msec after MAP upstroke, a period of intrinsic increase in repolarization dispersion. During the pressure pulse, MAPs revealed an additional increase in repolarization dispersion (time domain) by 9 +/- 6 msec (P < 0.01). The maximal difference in repolarization levels (voltage domain) between sites increased from 19 +/- 3% to 26 +/- 3% (P < 0.05). Earliest stretch-induced activation was observed near a site with early repolarization, while sites with late repolarization showed delayed activation.</AbstractText>Sudden myocardial stretch can elicit VF when it occurs during a vulnerable window that is based on repolarization inhomogeneity. Stretch pulses applied during this vulnerable window can lead to nonuniform activation. Repolarization dispersion might play a crucial role in the occurrence of fatal tachyarrhythmias during commotio cordis.</AbstractText> |
9,347 | [The use of implantable cardioverter-defibrillators (ICD) in children and adolescents]. | The compelling safety and efficacy data in numerous large, blinded trials on adult patients, and the progress in device- and leadtechnology have led to increasing use of implantable cardioverter defibrillators in pediatric patients. The purpose of our study was to assess the efficacy and safety of ICD in the pediatric age group of a tertiary referral centre.</AbstractText>Between March 1998 and October 2003 12 patients underwent ICD-implantation. The mean age at implantation was 14,8 years with a range between 10-17 years. The underlying cardiac disorders included long QT-syndrome in 4 patients, ventricular fibrillation in 3 patients, dilated cardiomyopathy in 4 patients, and congenital heart disease in 1 patient (pulmonary atresia with ventricular septal defect after Rastelli repair). All patients received a transvenous ICD-system (VVI-ICD in 4 patients, DDD-ICD in 8 patients).</AbstractText>The mean follow up was 35 months (6-68 months). During this period there were no severe complications nor mortality. We haven't seen infections, thromboembolic complications or lead-perforations. 2 patients (17 %) received appropriate DC-shocks, 1 patient (8 %) received an inappropriate DC-shock. 10 patients (83 %) had no malignant ventricular arrhythmia under medical therapy. 2 patients (17 %) required revision because of lead-dysfunction. In 2 patients with DCM the device was explanted during orthotopic heart transplantation.</AbstractText>Our data demonstrate that advances in device- and leadtechnology have resulted in a decrease of severe complications in the pediatric age group. We conclude that ICD-implantation represents a safe and effective therapy for children and adolescents with lifethreatening ventricular dysrhythmias. Since it represents an invasive therapy, indication should be confined to patients with lifethreatening dysrhythmias according to the guidelines of the American Heart Association.</AbstractText> |
9,348 | Are elderly patients with suspected HF misdiagnosed? A primary health care center study. | Few studies are published on heart failure patients in primary health care, in elderly in advanced age.</AbstractText>The purpose of this study was to examine the accuracy of the diagnosis of heart failure in all men and women with focus on age and gender.</AbstractText>The patients were recruited from one selected primary health care in the city of Skellefteå, Sweden. The general practitioners included all patients who had symptoms and signs indicating heart failure. The patients were then referred for an echocardiographic examination and a final cardiology consultation.</AbstractText>The general practitioners identified 121 women and 49 men with suspected heart failure of whom 39% (51 women and 16 men) were above 80 years. Women were significantly older than men (mean age 78 and 75 years, respectively, p = 0.03). The main symptom was dyspnoea (80%). Confirmed heart failure was verified in 45% of the patients and was significantly more common in men than women (p = 0.02). Of all men and women above 80 years, 75% and 22%, respectively (p = 0.01) had a verified systolic heart failure, while there were no significant gender differences in patients younger than 80. In a multivariate regression analysis taking gender, age, smoking, atrial fibrillation, hypertension, angina, myocardial infarction and diabetes into account, myocardial infarction (OR = 4.3, CL = 1.8-10.6) hypertension (OR = 3.4, CI = 1.6-6.9) atrial fibrillation (OR = 2.8, CL = 1.0-7.9) remained significantly predictive of a confirmed diagnosis of heart failure.</AbstractText>This study showed the difficulty of diagnosing heart failure accurately based only on clinical symptoms, especially in women above 80 years.</AbstractText>2007 S. Karger AG, Basel</CopyrightInformation> |
9,349 | Atrial fibrillation after percutaneous coronary intervention: predictive importance of clinical, angiographic features and P-wave dispersion. | Atrial fibrillation (AF) may occur during or after percutaneous coronary interventions (PCI). The purpose of the study was to determine the clinical, angiographic and electrophysiological predictors of AF after PCI. 225 patients undergoing PCI (mean age of 65 +/- 11 years) who had sinus rhythm (SR) before balloon inflation were taken to study. Of these 22 developed AF in catheterization laboratory after balloon inflation or in 24 h following PCI (AF group), 203 did not (SR group). The patients in AF group were older (67 +/- 9 vs. 63 +/- 8 years, p < 0.05) and their ventricular ejection fraction was lower than SR group (56 +/- 5 vs. 45 +/- 7%, p < 0.05). The P-wave dispersion was significantly higher in AF group than SR group (53 +/- 8 vs. 29 +/- 10 ms, p < 0.001). For the patients with ST elevation myocardial infarction, the time from the onset of symptoms to balloon inflation was 3.7 +/- 1.7 h in SR group. It was longer in AF group (4.1 +/- 1.8 h, p < 0.05). TIMI perfusion grades 2 and 3 were achieved in 23 of 27 patients in SR group, and 5 of 8 patients in AF group. Multivessel disease was documented in 93 of the patients in SR group, and 12 in AF group. Clinical reperfusion was thought to be established in 20 in SR group, and 4 in AF group. In conclusion, our results show the importance of clinical factors, angiographic results and P-wave analysis in prediction of AF following PCI. |
9,350 | Acute therapy of maternal and fetal arrhythmias during pregnancy. | Atrial premature beats are frequently diagnosed during pregnancy. Supraventricular tachycardia (atrial tachycardia, atrioventricular nodal reentrant tachycardia, circus movement tachycardia) is diagnosed less frequently. For acute therapy, electrical cardioversion with 50 to 100 J is indicated in all unstable patients. In stable supraventricular tachycardia, the initial therapy includes vagal maneuvers to terminate tachycardias. For short-term management, when vagal maneuvers fail, intravenous adenosine is the first choice drug and may safely terminate the arrhythmia. Ventricular premature beats are also frequently present during pregnancy and are benign in most patients; however, malignant ventricular tachyarrhythmias (sustained ventricular tachycardia, ventricular flutter, or ventricular fibrillation) may occur. Electrical cardioversion is necessary in all patients who are hemodynamically unstable with life-threatening ventricular tachyarrhythmias. In hemodynamically stable patients, initial therapy with ajmaline, procainamide, or lidocaine is indicated. In patients with syncopal ventricular tachycardia, ventricular fibrillation, ventricular flutter, or aborted sudden death, an implantable cardioverter-defibrillator is indicated. In patients with symptomatic bradycardia, a pacemaker can be implanted using echocardiography at any stage of pregnancy. The treatment of the pregnant patient with cardiac arrhythmias requires important modifications of the standard practice of arrhythmia management. The goal of therapy is to protect the patient and fetus through delivery, after which chronic or definitive therapy can be administered. |
9,351 | Rewarming rates in urban patients with hypothermia: prediction of underlying infection. | In the urban setting, hypothermia is commonly associated with illness or intoxication, with death often secondary to infection.</AbstractText>To evaluate factors that affect the rewarming rate (RWR) and the ability of the RWR and other clinical markers to predict the presence or absence of underlying infection in an adult urban population.</AbstractText>This was a prospective observational study of hypothermic patient visits to a large emergency department. Serial temperatures were obtained during rewarming to construct rewarming curves. Rewarming modalities selected by emergency physicians were correlated with admission temperatures. Univariate associates of RWR and infection were assessed.</AbstractText>The authors identified 96 patient visits. The median temperature was 89.5 degrees F (31.9 degrees C; range, 73.0 degrees F to 95.0 degrees F [22.8 degrees C to 35.0 degrees C]). Thirteen patients had temperatures of < 80.0 degrees F (26.0 degrees C). Seven died within 14 hours of presentation; six, of infection. No patient experienced ventricular fibrillation. Potential candidate predictors of infection from a multivariate analysis were a RWR of < 1.80 degrees F (1.0 degrees C) per hour and a serum albumin of < 2.7 g/dL. Rapid rewarming was associated with the absence of infection and a temperature below 86.0 degrees F (30.0 degrees C). In patients without significant underlying illness, rewarming rates appeared to be independent of the modality of rewarming.</AbstractText>Rewarming rates reflect intrinsic capacity for thermogenesis. Increased RWRs were associated with the absence of infection. The achievement of normothermia did not prevent death in infected patients. Initiation of invasive rewarming in urban patients with hypothermia who have not had hypothermic cardiac arrest may be unwarranted. Management of this population should emphasize support, detection, and treatment of underlying illness.</AbstractText> |
9,352 | Genetic and biophysical basis for bupivacaine-induced ST segment elevation and VT/VF. Anesthesia unmasked Brugada syndrome. | Brugada syndrome is an inherited disease associated with sudden cardiac death. The electrocardiographic pattern associated with Brugada syndrome has been linked to the use of sodium channel blockers, including antiarrhythmics, trycyclics and anesthetics.</AbstractText>We report a case of bupivacaine-induced Brugada syndrome, in which we investigated the genetic, biophysical and path physiological mechanism involved.</AbstractText>The patient developed a Brugada-like electrocardiographic pattern twice under the influence of bupivacaine. The first occurrence was accompanied by ventricular tachycardia (VT) which subsided after withdrawal of the anesthetic. The VT was also observed during co-administration of diltiazem and isosorbide-5-mononitrate, agents thought to facilitate ST segment elevation in the Brugada syndrome. Genetic analysis revealed a missense mutation in the alpha subunit of the cardiac sodium channel, SCN5A. Biophysical analysis by whole-cell patch-clamping revealed a reduction in sodium current as a result of the mutation. The study of bupivacaine in the wedge model revealed use-dependent changes in conduction, heterogeneous loss of the action potential dome in RV epicardium and phase 2 re-entry when the preparations were pretreated with low concentrations of the calcium channel blocker verapamil.</AbstractText>Our findings indicate that bupivacaine may induce the electrocardiographic and arrhythmic manifestations of the Brugada syndrome in silent carriers of SCN5A mutations. The data have important implications in the management of patients who develop ST segment elevation when under the influence of anesthetics such as bupivacaine.</AbstractText> |
9,353 | Elevated defibrillation thresholds in patients undergoing biventricular defibrillator implantation: incidence and predictors. | The biventricular implantable cardioverter-defibrillator (ICD) is an important therapy for select patients with severe heart failure. Given reported risk factors for elevated defibrillation thresholds (DFTs), patients undergoing biventricular ICD placement would be suspected of having a higher incidence of elevated DFT.</AbstractText>The purpose of this study was to examine the clinical predictors and mortality risk of elevated DFTs in patients receiving a biventricular ICD.</AbstractText>Characteristics of patients undergoing biventricular ICD placement with an elevated DFT were compared to those without an elevated DFT.</AbstractText>An elevated DFT was found in 14 (12%) of 121 patients. Mean QRS duration was 210 +/- 50 ms in the elevated DFT group and 171 +/- 36 ms in the normal DFT group (P = .01). Patients with a QRS duration >or=200 ms were more likely to have an elevated DFT than those with a duration <200 ms (odds ratio 13.4, 95% confidence interval 3.1-66.7, P <.01). No other clinical characteristics were associated with an elevated DFT. More than 90% of patients with an elevated DFT achieved an adequate safety margin through system modification or manipulation of their drug regimen. An elevated DFT did not have an impact on 2-year mortality.</AbstractText>Patients with a biventricular ICD had a 12% incidence of elevated DFT in our sequential patient cohort. QRS duration prior to biventricular ICD placement is the most powerful predictor of patients at risk for an elevated DFT. An elevated DFT does not have an impact on mortality, perhaps because of successful implementation of system modifications to ensure an adequate defibrillation safety margin.</AbstractText> |
9,354 | Protective role of protein kinase C epsilon activation in ischemia-reperfusion arrhythmia. | Ischemic heart disease carries an increased risk of malignant ventricular tachycardia (VT), fibrillation (VF), and sudden cardiac death. Protein kinase C (PKC) epsilon activation has been shown to improve the hemodynamics in hearts subjected to ischemia/reperfusion. However, very little is known about the role of epsilon PKC in reperfusion arrhythmias. Here we show that epsilon PKC activation is anti-arrhythmic and its inhibition is pro-arrhythmic.</AbstractText>Langendorff-perfused isolated hearts from epsilonPKC agonist (epsilonPKC activation), antagonist (epsilonPKC inhibition) transgenic (TG), and wild-type control mice were subjected to 30 min stabilization period, 10 min global ischemia, and 30 min reperfusion. Action potentials (APs) and calcium transients (CaiT) were recorded simultaneously at 37 degrees C using optical mapping techniques. The incidence of VT and VF was assessed during reperfusion.</AbstractText>No VT/VF was seen in any group during the stabilization period in which hearts were perfused with Tyrode's solution. Upon reperfusion, 3 out of the 16 (19%) wild-type mice developed VT but no VF. In epsilonPKC antagonist group, in which epsilonPKC activity was downregulated, 10 out of 13 (76.9%) TG mice developed VT, of which six (46.2%) degenerated into sustained VF upon reperfusion. Interestingly, in epsilonPKC agonist mice, in which the activity of epsilonPKC was upregulated, no VF was observed and only 1 out of 12 mice showed only transient VT during reperfusion. During ischemia and reperfusion, CaiT decay was exceedingly slower in the antagonist mice compared to the other two groups.</AbstractText>Moderate in vivo activation of epsilonPKC exerts beneficial antiarrhythmic effect vis-a-vis the lethal reperfusion arrhythmias. Abnormal CaiT decay may, in part, contribute to the high incidence of reperfusion arrhythmias in the antagonist mice. These findings have important implications for the development of PKC isozyme targeted therapeutics and subsequently for the treatment of ischemic heart diseases.</AbstractText> |
9,355 | Endothelin receptors, localized in sympathetic nerve terminals of the heart, modulate norepinephrine release and reperfusion arrhythmias. | Endothelin (ET)-1 is an endogenous vasoconstrictor which modulates norepinephrine (NE) release in myocardial ischemia reperfusion. Recent studies have demonstrated the pro- or anti-arrhythmic effects in reperfusion. The present studies were undertaken to test the hypothesis that ET receptors located in sympathetic nerve terminals modulate NE release associated with reperfusion arrhythmias (ventricular fibrillation; VF). Immunohistochemical studies showed that both ETA and ETB receptors exist in the sympathetic nerve varicosities, which were stained positive for tyrosine hydroxylase (TH) in the left ventricular wall in guinea pigs. Isolated guinea pig hearts were subjected to 20 min of normothermic global ischemia followed by 30 min reperfusion. Exogenously applied ET-1 (0.1 and 1 nM) dose-dependently increased NE release and the duration of VF, but these responses were significantly suppressed with the Na(+)/H(+) exchanger inhibitor, 5-(N-ethyl-N-isopropyl)-amiloride (10 microM). The ETA receptor antagonist (BQ123, 1 microM) and nonselective ET receptor antagonist (PD142893, 1 microM) significantly attenuated NE release and VF, whereas the ETB receptor antagonist (BQ788,300 nM) markedly elevated NE release but did not affect VF. These studies provide the first evidence that both ETA and ETB receptors, located in the sympathetic nerve varicosities, modulate NE release, at least in part, in association with reperfusion arrhythmias. |
9,356 | [Coronary embolism with apical ballooning complicating electrical cardioversion--is it part of the apical ballooning syndrome? Case report and review of the literature]. | A case of thromboembolic left anterior descending artery occlusion following electrical cardioversion for atrial fibrillation is described. A 66-year-old female patient presenting with exertional angina pectoris and atrial fibrillation was subjected to coronary angiography, ventriculography and transesophageal echocardiography. No significant coronary stenoses were found, left ventricular systolic function and regional wall motion were normal, and she had no intracardiac thrombi. Direct-current cardioversion was complicated by asystole which was managed by cardiac massage and 1 mg atropine and 1 mg adrenaline intravenously. Shortly afterwards, the patient regained a normal sinus rhythm. She remained hypotensive and developed ST segment elevation over the chest leads. Angiography was repeated and showed apical ballooning and thromboembolic subtotal occlusion of the proximal LAD, which migrated to the periphery and subsequently disappeared with regain of TIMI 3 flow by the end of angiography. 4 months later, a normal left ventricular global and regional function was seen in echocardiography.</AbstractText>At least part of the apical ballooning syndrome patients are a sequel of transient thromboembolic occlusions.</AbstractText>Therefore, all patients with the diagnosis of coronary embolism in the period from September 2004 to September 2005 were analyzed retrospectively.</AbstractText>Further three patients had coronary artery embolism (two females, one male; age 69-76 years). Two patients had apical ballooning, and one showed global hypokinesia (known dilated cardiomyopathy). Cardiac markers were slightly elevated. ST segment elevation was seen in two patients and T-wave inversion in one. All had risk factors for embolization and two had an additional triggering factor. Both cases with apical ballooning had regained a normal ejection fraction at follow-up.</AbstractText>This case series probably bridges the gap between two as yet separate disease entities, namely the apical ballooning syndrome and coronary emboli. The time factor probably plays the pivotal role in determining whether the apical ballooning alone or also an embolus is seen. It seems possible that some patients presenting with apical ballooning are unrecognized coronary thromboembolic cases.</AbstractText> |
9,357 | Atrial fibrillation and pacing algorithms. | Pacing prevention algorithms have been introduced in order to maximize the benefits of atrial pacing in atrial fibrillation prevention. It has been demonstrated that algorithms actually keep overdrive atrial pacing, reduce atrial premature contractions, and prevent short-long atrial cycle phenomenon, with good patient tolerance. However, clinical studies showed inconsistent benefits on clinical endpoints such as atrial fibrillation burden. Factors which may be responsible for neutral results include an already high atrial pacing percentage in conventional DDDR, non-optimal atrial pacing site and deleterious effects of high percentages of apical ventricular pacing. Atrial antitachycardia pacing (ATP) therapies are effective in treating spontaneous atrial tachyarrhythmias, mainly when delivered early after arrhythmia onset and/or on slower tachycardias. Effective ATP therapies may reduce atrial fibrillation burden, but conflicting evidence does exist as regards this issue, probably because current clinical studies may be underpowered to detect such an efficacy. Wide application of atrial ATP may reduce the need for hospitalizations and electrical cardioversions and favorably impact on quality of life. Consistent monitoring of atrial and ventricular rhythm as well as that of ATP effectiveness may be extremely useful for optimizing device programming and pharmacological therapy. |
9,358 | Pacemaker prevention therapy in drug-refractory paroxysmal atrial fibrillation: reliability of diagnostics and effectiveness of prevention pacing therapy in Vitatron selection device. | Atrial fibrillation (AF), the most common and rising disorder of cardiac rhythm, is quite difficult to control and/or to treat. Non pharmacological therapies for AF may involve the use of dedicated pacing algorithms to detect and prevent atrial arrhythmia that could be a trigger for AF onset. Selection 900E/AF2.0 Vitatron DDDRP pacemaker (1) keeps an atrial arrhythmia diary thus providing detailed onset reports of arrhythmias of interest, (2) provides us data about the number of premature atrial contractions (PACs) and (3) plots heart rate in the 5 minutes preceding the detection of an atrial arrhythmia. Moreover, this device applies four dedicated pacing therapies to reduce the incidence of atrial arrhythmia and AF events.</AbstractText>To analyze the reliability to record atrial arrhythmias and evaluate effectiveness of its AF preventive pacing therapies.</AbstractText>We enrolled 15 patients (9 males and 6 females, mean age of 71+/-5 years, NYHA class I-II), with a DDDRP pacemaker implanted for a "bradycardia-tachycardia" syndrome, with advanced atrioventricular conduction disturbances. We compared the number and duration of AF episodes' stored in the device with a contemporaneous 24h Holter monitoring. After that, we switched on the atrial arrhythmias detecting algorithms, starting from an atrial rate over 180 beats per minute for at least 6 ventricular cycles, and ending with at least 10 ventricular cycles in sinus rhythm. Thereafter, in order to evaluate the possible reduction in PACs number and in number and duration of AF episodes, we tailored all the four pacing preventive algorithms. Patients were followed for 24+/-8 months (from 20 to 32 months).</AbstractText>All 59 atrial arrhythmia episodes occurred in the first part of this trial, were correctly recorded by both systems, with a correlation coefficient (r) of 0.96. During the follow-up, we observed a significant reduction not only in PACs number (from 83+/-12/day to 2.3+/-0.8/day) but also in AF episodes (from 46+/-7/day to 0.12+/-0.03/day) and AF burden (from 93%+/-6% to 0.3%+/-0.06%). An increase in atrial pacing percentages (from 3%+/-0.5% to 97%+/-3%) was also contemporaneously observed.</AbstractText>In this pacemaker, detection of atrial arrhythmia episodes is highly reliable, thus making available an appropriate monitoring of heart rhythm, mainly suitable in AF asymptomatic patients. Moreover, the significant reduction of atrial arrhythmia episodes indicates that this might represent a suitable therapeutic option for an effective preventive therapy of AF in paced brady-tachy patients.</AbstractText> |
9,359 | Andersen-Tawil syndrome. | Andersen-Tawil syndrome (ATS) is a rare condition consisting of ventricular arrhythmias, periodic paralysis, and dysmorphic features. In 2001, mutations in KCNJ2, which encodes the a subunit of the potassium channel Kir2.1, were identified in patients with ATS. To date, KCNJ2 is the only gene implicated in ATS, accounting for approximately 60% of cases. ATS is a unique channelopathy, and represents the first link between cardiac and skeletal muscle excitability. The arrhythmias observed in ATS are distinctive; patients may be asymptomatic, or minimally symptomatic despite a high arrhythmia burden with frequent ventricular ectopy and bidirectional ventricular tachycardia. However, patients remain at risk for life-threatening arrhythmias, including torsades de pointes and ventricular fibrillation, albeit less commonly than observed in other genetic arrhythmia syndromes. The characteristic heterogeneity at both the genotypic and phenotypic levels contribute to the continued difficulties with appropriate diagnosis, risk stratification, and effective therapy. The initial recognition of a syndromic association of clinically diverse symptoms, and the subsequent identification of the underlying molecular genetic basis of ATS has enhanced both clinical care, and our understanding of the critical function of Kir2.1 on skeletal muscle excitability and cardiac action potential. |
9,360 | Brain tissue oxygen pressure and cerebral metabolism in an animal model of cardiac arrest and cardiopulmonary resuscitation. | Direct measurement of brain tissue oxygenation (PbtO2) is established during spontaneous circulation, but values of PbtO2 during and after cardiopulmonary resuscitation (CPR) are unknown. The purpose of this study was to investigate: (1) the time-course of PbtO2 in an established model of CPR, and (2) the changes of cerebral venous lactate and S-100B.</AbstractText>In 12 pigs (12-16 weeks, 35-45 kg), ventricular fibrillation (VF) was induced electrically during general anaesthesia. After 4 min of untreated VF, all animals were subjected to CPR (chest compression rate 100/min, FiO2 1.0) with vasopressor therapy after 7, 12, and 17 min (vasopressin 0.4, 0.4, and 0.8 U/kg, respectively). Defibrillation was performed after 22 min of cardiac arrest. After return of spontaneous circulation (ROSC), the pigs were observed for 1h.</AbstractText>After initiation of VF, PbtO2 decreased compared to baseline (mean +/- SEM; 22 +/- 6 versus 2 +/- 1 mmHg after 4 min of VF; P < 0.05). During CPR, PbtO2 increased, and reached maximum values 8 min after start of CPR (25 +/- 7 mmHg; P < 0.05 versus no-flow). No further changes were seen until ROSC. Lactate, and S-100B increased during CPR compared to baseline (16 +/- 2 versus 85 +/- 8 mg/dl, and 0.46 +/- 0.05 versus 2.12 +/- 0.40 microg/l after 13 min of CPR, respectively; P < 0.001); lactate remained elevated, while S-100B returned to baseline after ROSC.</AbstractText>Though PbtO2 returned to pre-arrest values during CPR, PbtO2 and cerebral lactate were lower than during post-arrest reperfusion with 100% oxygen, which reflected the cerebral low-flow state during CPR. The transient increase of S-100B may indicate a disturbance of the blood-brain-barrier.</AbstractText> |
9,361 | Short QT syndrome: a case report and review of literature. | The short QT syndrome has been recently recognised as a genetic ion channel dysfunction. This new clinical entity is associated with an incidence of sudden cardiac death, syncope, and atrial fibrillation in otherwise healthy individuals. The distinctive ECG pattern consists of an abnormally short QT interval, a short or even absent ST segment and narrow T waves. A 30-year-old resuscitated woman with short QT syndrome is described together with an example of the classic ECG characteristics. A short-coupled variant of torsade de pointes was reveal on Holter recordings. The implantable cardioveter defibrillator seems to be the therapy of choice to prevent from sudden cardiac death. Quinidine proved to be efficient in prolonging the QT interval and rendering ventricular tachyarrhythmias non-inducible in patients with a mutation in KCNH2 (HERG). Our preliminary data suggest amiodarone combined with beta-blocker may be helpful in treating episodes of polymorphic ventricular tachycardia for patients with an unknown genotype. Because the short QT syndrome often involves young patients with an apparently normal heart, it is imperative for physicians to recognize the clinical features of the short QT syndrome in making a timely correct diagnosis. |
9,362 | Increasing first responder CPR during resuscitation of out-of-hospital cardiac arrest using automated external defibrillators. | Evidence supports that increasing the balance of "hands-on" CPR may improve survival in ventricular fibrillation out-of-hospital cardiac arrest (OHCA). We assessed whether training and/or AED reconfiguration was associated with an increase in the proportion of time during which CPR was performed between first and second stacks of shocks.</AbstractText>The investigation was a cohort study of 291 persons who suffered ventricular fibrillation OHCA and were treated with at least two stacks of AED shocks by emergency medical services (EMS) first-tier responders. In January 2003, first-tier providers were retrained regarding the importance of CPR. In addition, a subset of AEDs was reconfigured to remove continuous fibrillation detection and its associated voice prompts as to be comparable with other AED models. The amount of time spent on CPR was assessed through review of AED electronic and audio recordings to compare the pre-intervention (n = 241) and post-intervention periods (n = 50).</AbstractText>The proportion of time spent performing hands-on CPR between first and second stacks of shocks was 0.40 in the pre-intervention period compared to 0.51 in the post-intervention period (p = 0.001). The difference was greatest for AEDs where EMS was retrained and the AED reconfigured (0.33 versus 0.50, p = 0.01). No difference in survival was detected between the pre- and post-intervention periods (24.9% versus 28.0%, p = 0.65).</AbstractText>An intervention consisting of retraining and AED reconfiguration was associated with an increase in the proportion of time spent performing CPR between first and second stacks of shocks by first-tier EMS. Whether this increase improves patient outcomes requires additional study.</AbstractText> |
9,363 | Greater antiarrhythmic activity of acute 17beta-estradiol in female than male anaesthetized rats: correlation with Ca2+ channel blockade. | Female sex hormones may protect pre-menopausal women from sudden cardiac death. We therefore investigated the effects of the main female sex hormone, 17beta-estradiol, on ischaemia-induced cardiac arrhythmias and on the L-type Ca2+ current (ICaL).</AbstractText>In vivo experiments were performed in pentobarbital-anaesthetized rats subjected to acute coronary artery occlusion. ICaL was measured by the whole-cell patch-clamp technique, in rat isolated ventricular myocytes.</AbstractText>Acute intravenous administration of 17beta-estradiol as a bolus dose followed by a continuous infusion, commencing 10 min before coronary artery occlusion, had dose-dependent antiarrhythmic activity. In female rats 300 ng kg(-1) + 30 ng kg(-1) min(-1) 17beta-estradiol significantly reduced the number of ventricular premature beats (VPBs) and the incidence of ventricular fibrillation (VF). A ten fold higher dose of 17beta-estradiol was required to cause similar effects in male rats. In vitro 17beta-estradiol reduced peak ICaL in a concentration-dependent manner. The EC50 was ten-fold higher in male myocytes (0.66 microM) than in females (0.06 microM).</AbstractText>These results indicate that 17beta-estradiol has marked dose-dependent antiarrhythmic activity that is greater in female rats than in males. A similar differential potency in blocking ICaL in myocytes from female and male rats can account for this effect. This provides an explanation for the antiarrhythmic activity of 17beta-estradiol and gender-selective protection against sudden cardiac death.</AbstractText> |
9,364 | Sex hormones and arrhythmia in myocardial ischemia. | The mechanisms by which gender affects cardiac electrophysiological parameters and alters the predisposition to certain arrhythmias are not well understood, although differences in the expression and function of ion channels and in the activation of the autonomic nervous system may contribute. In their study Philp and coworkers address the issue of the effect of 17beta-estradiol on ventricular vulnerability in a rat model of ischemia. Their data show that there is a dose-dependent antiarrhythmic activity of 17beta-estradiol administration with suppression ventricular premature beats, ventricular tachycardia and ventricular fibrillation during ischemia. Furthermore they show a dose-dependent blockage of I(CaL) by 17beta-estradiol which is again stronger in female than in male mice. They postulate that the shown gender-selective, concentration-dependent inhibition of I(CaL) is sufficient to account for the reduction in ischaemia-induced arrhythmia. With this data they have added important information on the influence of sex hormones on cardiac electrophysiology under pathophysiological conditions. |
9,365 | Familial sudden death is an important risk factor for primary ventricular fibrillation: a case-control study in acute myocardial infarction patients. | Primary ventricular fibrillation (VF) accounts for the majority of deaths during the acute phase of myocardial infarction. Identification of patients at risk for primary VF remains very poor.</AbstractText>We performed a case-control study in patients with a first ST-elevation myocardial infarction (STEMI) to identify independent risk factors for primary VF. A total of 330 primary VF survivors (cases) and 372 controls were included; patients with earlier infarcts or signs of structural heart disease were excluded. Baseline characteristics, including age, gender, drug use, and ECG parameters registered well before the index infarction, as well as medical history, were not different. Infarct size and location, culprit coronary artery, and presence of multivessel disease were similar between groups. Analysis of ECGs performed at hospital admission for the index STEMI revealed that cumulative ST deviation was significantly higher among cases (OR per 10-mm ST deviation 1.59, 95% CI 1.25 to 2.02). Analysis of medical histories among parents and siblings showed that the prevalence of cardiovascular disease was similar between cases and controls (73.1% and 73.0%, respectively); however, familial sudden death occurred significantly more frequently among cases than controls (43.1% and 25.1%, respectively; OR 2.72, 95% CI 1.84 to 4.03).</AbstractText>In a population of STEMI patients, the risk of primary VF is determined by cumulative ST deviation and family history of sudden death.</AbstractText> |
9,366 | Cardiac effects of ST-6, a novel cyclohexane dicarboximide derivative. | Na(+) channel blockade is thought to be involved in the cardioprotection against ischemia/reperfusion injury. We synthesized various cyclohexane dicarboximides and examined their cardioprotective actions. Some of these derivatives had local anesthetic action and were capable of enhancing post-hypoxic contractile recovery of the isolated perfused rat heart. Among them, 2-[4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]butyl]hexahydro-1H-isoindol-1,3(2H)-dione hydrochloride (ST-6) was most effective in the enhancement of post-hypoxic contractile recovery of isolated perfused rat hearts subjected to 20-min hypoxia and 45-min reoxygenation. This enhanced recovery by 30 mg/min of ST-6 was associated with attenuation of Na(+), but not of Ca(2+), accumulation during ischemia and prevention of creatine kinase release from the heart during reperfusion. When hearts subjected to 30-min ischemia followed by 60-min reperfusion were pretreated with 30 muM ST-6, the post-ischemic contractile recovery was enhanced and ischemia-induced accumulation of Na(+), as well as reperfusion-induced accumulation of Na(+) and Ca(2+), was attenuated. Also the reperfusion-induced release of creatine kinase was reduced, while restoration of myocardial high-energy phosphates was enhanced during reperfusion. Na(+) channel blockade by ST-6, as assessed by the depression of the Vmax of the action potential, was similar to that produced by flecainide but more pronounced than with either lidocaine or disopyramide. ST-6, 1, or 2 mg/kg i.v. or 10 mg/kg i.p., abolished ventricular fibrillation induced by 4 min of ischemia and subsequent 4 min of reperfusion in rats. The prevention of ventricular fibrillation by the continuous injection of 0.2 mg/kg per min ST-6 from the first min after ischemia to the end of reperfusion was similar in degree to that produced by 0.1 mg/kg/min lidocaine or 0.5 mg/kg/min diltiazem. The former treatment elicited a transient decrease in the systemic blood pressure in anesthetized rats during ischemia, whereas treatment with the latter did not reduce systemic blood pressure. These findings suggest that ST-6 may have cardioprotective effects in ischemia/reperfusion injury. |
9,367 | Cardiac resynchronisation therapy for heart failure. | Cardiac resynchronisation therapy (CRT) reduces symptoms and improves left ventricular function in chronic heart failure (CHF) patients with left ventricular systolic dysfunction and prolonged QRS duration. Recent studies have demonstrated a reduction in mortality associated with CRT. When combined with an implantable cardioverter defibrillator (ICD) reduction in mortality is likely to reduce further. Cardiac resynchronisation therapy is well tolerated and free from compliance issues and therefore should be considered for all suitable patients. Identifying patients who will derive maximum benefit requires further study and has health economic implications. We review here the CRT trial evidence as well as the implantation technique and complications. We also describe a case report where an intra-aortic balloon pump was used successfully as a bridge to CRT to treat a patient with end-stage heart failure. |
9,368 | Assessment of rhythm and rate control in patients with atrial fibrillation. | A recent series of randomized prospective clinical trials that compared rate control with rhythm control in patients with atrial fibrillation (AF) found no significant difference in primary outcome between the two strategies. However, these trials lacked clear criteria for defining "successful" rate or rhythm control. Various measures have been used to gauge the success of antiarrhythmic drug therapy, including time to first recurrence of AF, any AF recurrence, AF burden, and a reduction in symptoms. Determining the success of antiarrhythmic therapy can be relatively straightforward by using how patients feel during therapy as a key endpoint. Most patients are satisfied with a major reduction in symptomatic AF episodes and can live comfortably with occasional episodes of AF. For those who are bothered by even infrequent, brief AF episodes, a treatment regimen that eliminates nearly all AF recurrences is required, although often hard to achieve. Catheter ablation may be necessary to achieve a successful outcome in these patients. Suppression of AF in a patient at high risk of stroke does not, however, remove the need for concomitant warfarin therapy. The endpoints of ventricular rate control are not clear, and the recently published rhythm versus rate control trials lacked standard criteria for judging acceptable rate control. One relatively simple method is to try and achieve a 24-hour heart rate that mimics expected normal sinus rhythm. It is important to achieve good rate control to minimize symptoms and the risk of tachycardia-mediated cardiomyopathy. |
9,369 | Dronedarone: an emerging agent with rhythm- and rate-controlling effects. | Of current antiarrhythmic agents, amiodarone is among the most effective with the additional advantage of having little proarrhythmic potential. However, it can cause potentially serious extracardiac side effects, stimulating the search for safer derivatives. Dronedarone, a new antiarrhythmic drug that is structurally related to amiodarone, lacks an iodine moiety and, thus, amiodarone's iodine-related organ toxicity, while its methane sulfonyl group decreases lipophilicity so shortening half-life and decreasing tissue accumulation. Electrophysiological studies show that dronedarone shares amiodarone's multichannel blocking effects, inhibiting transmembrane Na(+), K(+), Ca(2+), and slow L-type calcium channels, as well as its antiadrenergic effects. Unlike amiodarone, it has little effect at thyroid receptors. Possessing both rate- and rhythm-control properties, dronedarone has proved safe and effective in preventing recurrence of atrial fibrillation (AF) in patients with persistent AF in the Dronedarone Atrial Fibrillation Study After Electrical Cardioversion (DAFNE) trial, the first prospective randomized trial to evaluate its efficacy and safety. Dronedarone has since undergone further extensive evaluation in three pivotal phase III trials. In two sister studies, the European Trial in Atrial Fibrillation or Flutter Patients Receiving Dronedarone for the Maintenance of Sinus Rhythm (EURIDIS) and American-Australian-African Trial with Dronedarone in Atrial Fibrillation/Flutter Patients for the Maintenance of Sinus Rhythm (ADONIS), dronedarone 400 mg b.i.d. showed significant efficacy against placebo in prevention of AF recurrence. Additionally, in patients with permanent AF, dronedarone was highly effective at controlling ventricular rate on top of standard rate-controlling therapies in the Efficacy and Safety of Dronedarone for the Control of Ventricular Rate during Atrial Fibrillation (ERATO) study. |
9,370 | The future of atrial fibrillation therapy. | Today management of atrial fibrillation (AF) centers on restoration and maintenance of normal sinus rhythm or control of the ventricular rate response to AF. Current guidelines state that rhythm and rate control strategies should be considered therapeutically equivalent, but recognize that no "one size fits all," an approach consistent with growing recognition of the heterogeneity of AF. As data from the Sotalol Amiodarone Atrial Fibrillation Efficacy Trial clearly demonstrate, conventional antiarrhythmics have a role in highly symptomatic AF accompanied by decreased quality of life. However, for many AF patients such drugs lack efficacy, have potentially serious side effects, and are poorly tolerated. In parallel with the development of more effective and safer antiarrhythmics, nontraditional approaches to prevention and treatment of AF are being explored. Treatments not considered "antiarrhythmic" that may prevent or forestall AF include aggressive antihypertensive therapy with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and some, but not all, beta-blockers and calcium channel antagonists, especially when used as adjunctive therapy. Other approaches include statins, steroids, and fish oil to reduce atrial fibrosis and inflammation, and pacemakers to prevent bradycardia-mediated AF and as a pacing preventive strategy in selected patients. Ablative techniques with potential to cure AF are gaining popularity, but are not yet simple, straightforward, and risk-free procedures. In the future, treatment of AF will progress beyond today's focus on AF as a purely electrocardiographic disease toward a patient and context-specific management strategy involving multiple treatment modalities. |
9,371 | The natural biochemical changes during ventricular fibrillation with cardiopulmonary resuscitation and the onset of postdefibrillation pulseless electrical activity. | The objective of this study was to document the biochemical changes during ventricular fibrillation (VF) with cardiopulmonary resuscitation (CPR), and to identify factors associated with postdefibrillation pulseless electrical activity (PD-PEA).</AbstractText>It has been reliably estimated that as much as 60% of out-of-hospital sudden cardiac death can be attributed to the onset of PD-PEA (Niemann JT, Cruz B, Garner D et al. Immediate countershock versus CPR before countershock in a 5-minute swine model of ventricular fibrillation arrest. Ann Emerg Med 2000;36:543-6). Previous attempts to treat reversible causes of pulseless electrical activity have not been successful clinically (Niemann JT, Stratton SJ, Cruz B, Lewis RJ. Outcome of out-of-hospital postcountershock asystole and pulseless electrical activity versus primary asystole and pulseless electrical activity. Crit Care Med 2001;29:2366-70).</AbstractText>This investigation used 22 studies on 14 anesthetized pigs breathing 100% oxygen. Ventricular fibrillation was induced with a right ventricular catheter electrode, and the chest was compressed with a pneumatically driven Chest Thumper (Michigan Instruments) (80-100 lb at 60/min). The electrocardiogram and aortic pressure were recorded continuously. Arterial pH, P(O2), P(CO2), Na+, K+, Ca2+, Cl-, SaO2, glucose, hematocrit, and hemoglobin level were measured at selected times. Ventricular defibrillation was achieved with transchest electrodes.</AbstractText>Typically, during VF with CPR, mean aortic pressure was 20 to 25 mm Hg. In all cases aortic P(O2) decreased to about 20% of the initial value in 10 minutes, and aortic blood K+ increased by 50% in 6 minutes. By 5 to 8 minutes, the incidence of PD-PEA was 50%.</AbstractText>Ventricular fibrillation duration, arterial K+, and arterial P(CO2) were statistically correlated with the onset of PD-PEA in this study. In addition, trends suggest an association of mean arterial blood pressure and arterial P(O2) with the onset of PD-PEA.</AbstractText> |
9,372 | [Early defibrillation in the community: breaking barriers to save lives]. | It is considered that in Spain, every year, we have more than 24,500 out-of-hospital cardiac arrests. Around 85% of these are secondary to ventricular fibrillation, with possibility of reversion in more than 90% if defibrillation is performed in the first minute of arrhythmia. However, if we delay this defibrillation, survival possibilities disappear in a few minutes. Clinical advances in last decades have not achieved satisfactory results in the treatment of cardiac arrest as survival rates at hospital discharge do not exceed 7%. Aware of this situation, the International Scientific Societies are recommending decreasing time to defibrillation, advising, at best, a time less than five minutes between the 112-call (emergency) and adequate electric discharge. Development of automated defibrillators in Emergency Medical Systems and their use by <<first responders>> of <<non-health care>> emergency services (police, fire fighters, etc) contribute to reach this objective. Because of this, Emergency Medical Systems are modifying their assistance strategies, to implement the early defibrillation as <<key to survival>>. Literature showed the effective value of automated defibrillators in the public areas but their efficiency level is less than that reached with the Emergency Services. Efficiency depends on multiple factors such as type of installation, accessibility level to emergency medical services or incidence rate of sudden cardiac arrest. Thus, their introduction should be preceded by a cost-effectiveness study. Effectiveness of automated defibrillators at home, where up to 80% of cardiac arrest are produced, has still not been evaluated. Nevertheless, in the USA, its marketing with this indication has been authorized. |
9,373 | Cardiac resynchronisation therapy in heart failure: current status. | Cardiac resynchronization in heart failure already has a history of 12 years. However, the major advances have been the result of large multi center trials dating from 2001. In all these trials patients with a LVEF < or = 35% were included, and a QRS above 120 msec. Follow up was from 3-36 months. The majority of these trials showed a positive effect in reduction of composite and points of death or hospitalization for major cardiovascular events. Many of these trials also showed a diminution of left ventricular and systolic diameter or volume. Even in NYHA class II patients an improvement was seen. Some unanswered questions still remain as regards the agreement on electrical or electromechanical dyssynchrony criteria. There is a number of patients with "wide" QRS who do not improve and conversely a number of patients with a narrow QRS who witness improvement. The benefit in patients with atrial fibrillation also remains unanswered. Finally the value of this modality in patients with mild heart failure or asymptomatic left ventricular systolic dysfunction, NYHA class I-II remains to be determined in large on going trials. Another question is whether biventricular or left ventricular patient is preferable. Finally whether biventricular patient should be complemented by a defibrillator insertion is being currently studied. Cardiac resynchronization therapy along or in combination with an ICD improves symptoms, reduces major morbidity and mortality in patients with a left ventricular EF<35%, ventricular dilatation and a QRS > or = 120 msec in NYHA class III-IV. Further indications are currently being examined. |
9,374 | Nifekalant hydrochloride administration during cardiopulmonary resuscitation improves the transmural dispersion of myocardial repolarization: experimental study in a canine model of cardiopulmonary arrest. | Because nifekalant hydrochloride (NIF) displayed a superior defibrillating effect on ventricular tachycardia/fibrillation (VT/VF) in cardiopulmonary arrest (CPA) patients, despite some QT prolongation, its effect on transmural dispersion of repolarization (TDR) in the left ventricle (LV) in an animal model of CPA was investigated.</AbstractText>Eight beagle dogs were created with a myocardial infarction under anesthesia, and then VT/VF induction by continuous stimulation and cardiopulmonary resuscitation (CPR) were repeated. NIF (0.3 mg/kg) was administered under acidotic conditions (pH 7.26). The QTc interval measured by Y-lead ECG showed no significant prolongation before and after NIF. The activation recovery interval (ARI) measured by 64-lead LV surface mapping showed minimum ARI prolongation (40%) by NIF without maximum ARI prolongation, and as a result the ARI dispersion decreased by 67%. The repolarization time (RPT) with the plunge electrode showed 13-19% prolongation in the subendocardium and subepicardium with CPR, but NIF prolonged the RPT in the middle layer alone (17%), and as a result Plunge-TDR decreased by 82% (n=8, p<0.05).</AbstractText>Administration of NIF during CPR decreased the TDR by RPT prolongation selectively in the middle layer. Because the subendocardial and subepicardial RPTs after CPR were already prolonged before NIF administration, it may have been the reason why the QT-prolonging effect of NIF was not reflected in the body surface ECG.</AbstractText> |
9,375 | Long-term outcome of implanted cardioverter defibrillators in survivors of out-of-hospital cardiac arrest of cardiac origin. | Little is known about the long-term outcome of implantable cardioverter defibrillator (ICD) therapy in survivors of out-of-hospital cardiac arrest (OHCA).</AbstractText>The frequency of lethal ventricular arrhythmias and whether ICD implantation can prevent recurrence of cardiac arrest were examined. Long-term (24.4+/-11.9 months) outcome was examined in 23 patients with OHCA who were treated with an ICD (OHCA group) and 35 patients without OHCA (non-OHCA group) who were treated with an ICD. Patients in both groups had same clinical backgrounds; however, those in the OHCA group showed a significantly lower incidence of induced ventricular arrhythmias (71%) than the non-OHCA group (96%). In the follow-up period, patients in the OHCA group had almost the same incidence of ICD discharge (30%) as patients in the non-OHCA group (40%). The rate of recurrence of ventricular fibrillation in the OHCA patients was 13%, and it was difficult to estimate the rate by induced ventricular arrhythmia.</AbstractText>The results suggest that ICD implantation for survivors of OHCA with favorable neurological recovery might be effective for preventing recurrence of cardiac arrest.</AbstractText> |
9,376 | Mechanisms of destabilization and early termination of spiral wave reentry in the ventricle by a class III antiarrhythmic agent, nifekalant. | Nifekalant (NF) is a novel class III antiarrhythmic agent that is effective in preventing life-threatening ventricular tachycardia/fibrillation (VT/VF). We investigated mechanisms of destabilization and early termination of spiral-type reentrant VT by NF in a two-dimensional subepicardial myocardial layer of Langendorff-perfused rabbit hearts (n = 21) using a high-resolution optical action potential mapping system. During basic stimulation, NF (0.1 microM) caused uniform prolongation of action potential duration (APD) without affecting conduction velocity and an increase of APD restitution slope. VTs induced by direct current stimulation in the presence of NF were of shorter duration (VTs > 30 s: 2/54 NF vs. 19/93 control). During VTs in control (with visible rotors), the wave front chased its own tail with a certain distance (repolarized zone), and they seldom met each other. The average number of phase singularity (PS) points was 1.31 +/- 0.14 per 665 ms (n = 7). In the presence of NF, the wave front frequently encountered its own tail, causing a transient breakup of the spiral wave or sudden movement of the rotation center (spatial jump of PS). The average number of PS was increased to 1.63 +/- 0.22 per 665 ms (n = 7, P < 0.05) after NF. The mode of spontaneous termination of rotors in control was in most cases (9/10, 90.0%) the result of mutual annihilation of counterrotating wave fronts. With NF, rotors frequently terminated by wave front collision with the atrioventricular groove (12/19, 63.2%) or by trapping the spiral tip in a refractory zone (7/19, 36.8%). Destabilization and early termination of spiral wave reentry induced by NF are the result of a limited proportion of excitable tissue after modulation of repolarization. |
9,377 | Sudden cardiac death: the lost fatty acid hypothesis. | Evidence that an excess of plasma free fatty acids (FFA) might lead to primary ventricular fibrillation and sudden cardiac death has hardened over the 36 years since the hypothesis was proposed. When the sympathetic nervous system is stimulated during the onset of an acute coronary syndrome, catecholamine-induced tissue lipolysis occurs, with a surge of plasma FFA. This may overload the acutely ischaemic myocardium and impair glucose utilization. Myocardial oxygen consumption can increase in regional areas of ischaemia, and could lead to abnormal electrophysiological conduction and refractoriness, with irreversible ventricular arrhythmias. Efforts to combat the adverse effects of excess FFA include beta-blockade, increasing glucose availability and extraction, or inhibition of lipolysis. This last approach appears promising, but no method has yet been clearly shown to prevent primary ventricular fibrillation or sudden cardiac death. The hypothesis remains viable. More research is needed to derive treatment that can be applied as soon as the onset of acute myocardial ischaemia is suspected. |
9,378 | Nonlinear organization of electrocardiogram and optical signals during ventricular fibrillation. | Although sympathetic activation may induce ventricular fibrillation (VF), little is known about how the autonomic nervous system influences its nonlinear organization. This study tested the hypothesis that autonomic receptor activation altered the nonlinear organization of VF.</AbstractText>Isolated rabbit hearts underwent retrograde perfusion with acetylcholine or norepinephrine added to the perfusate. Voltage-sensitive fluorescent images of the ventricular surface were obtained during sustained VF. Concurrent electrocardiogram and optical pixel signals underwent recurrence quantification analysis, which detects and quantifies patterns of repeating data sequences. Recurrence quantification analysis variables signify different aspects of nonlinearity.</AbstractText>Recurrence quantification analysis results showed that the electrocardiogram and pixel signals did not exhibit the same pattern of nonlinear organization during VF. Recurrence quantification analysis values were not dramatically altered from baseline by acetylcholine and norepinephrine but instead exhibited considerable variation.</AbstractText>An alteration in autonomic milieu diminished the nonlinear organization of VF, that is, autonomic receptor activation made VF less likely to behave in a repetitive pattern over time.</AbstractText> |
9,379 | Electrocardiogram interpretation and class I blocker challenge in Brugada syndrome. | Brugada syndrome is characterized by the presence of an electrocardiographic pattern of ST-segment elevation in leads V1 to V3 and a history of sudden cardiac death in the absence of structural heart disease [Brugada P, Brugada J. Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report. J Am Coll Cardiol 1992;20(6):1391]. The disease usually affects individuals in their 40s, at the prime of their life, and the appearance of cardiac arrest in these otherwise healthy individuals brings an important burden to families and to health care. Brugada syndrome is in several instances a familial disease, caused by mutations in SCN5A in up to 25% of the individuals [Chen Q, Kirsch GE, Zhang D, Brugada R, Brugada J, Brugada P, et al. Genetic basis and molecular mechanism for idiopathic ventricular fibrillation. Nature 1998;392(6673):293]. The identification of the electrocardiographic pattern in an individual will therefore trigger an important cascade of events in the families. Several family members, including children, will be under the scrutiny of a cardiologist to decide on preventive measures, especially if there is a history of sudden death in the family. The presence of abnormal repolarization patterns, which in otherwise sporadic individuals might be classified under normal variations, have become a diagnostic challenge for clinicians facing a family with the disease [Hong K, Brugada J, Oliva A, Berruezo-Sanchez A, Potenza D, Pollevick GD, et al. Value of electrocardiographic parameters and ajmaline test in the diagnosis of Brugada syndrome caused by SCN5A mutations. Circulation 2004;110(19):3023]. |
9,380 | Database testing of a subcutaneous monitor with wireless alarm. | We have tested the accuracy of detection of cardiac arrest in a cardiac event recorder that has the 4x4 cm sensor implanted, the recorder external, and the two connected by wireless. Storage and transmission is activated by the patient when symptoms are present or automatically when cardiac arrest is detected, in which case the recorder sounds a loud alarm to alert bystanders. It is the automatic mode that requires database testing of accuracy.</AbstractText>We obtained an appropriate database by mapping the chest in 60 ICD patients in sinus rhythm (SR) and induced ventricular fibrillation (VF), and deriving bipolar ECGs from adjacent electrodes located where the electrodes on the subQ sensor would be. (We then implanted the device in 2 dogs and demonstrated the equivalence of ECGs recorded on the skin to subcutaneous ECGs). A blinded selection of 10 of these 60 patients, together with 14 records from the MIT/BIH database, formed a testing set; the others were available for development and training of the detection algorithm.</AbstractText>In all 60 patients, ECGs from closely-spaced electrodes properly located on the chest appeared suitable for automatic VF detection. Formal testing with the 24-patient database yielded sensitivity and specificity of 100% in detecting VF.</AbstractText>It appears a 4 cm square subcutaneous sensor with electrodes at its corners can reliably monitor cardiac activity, accurately detect the occurrence of cardiac arrest, transmit the ECG to an external receiver, and produce an alarm when a life-threatening arrhythmia is detected.</AbstractText> |
9,381 | Surgery Insight: surgical methods to reverse left ventricular remodeling. | The management of patients with congestive heart failure (CHF) is challenging and the mortality with medical therapy alone is high. Left ventricular dilatation represents one of the strongest predictors of mortality in CHF, and a variety of surgical interventions have been proposed over the years to reverse ventricular remodeling. The most common surgical methods currently used are myocardial revascularization, left ventricular restoration, mitral valve repair, surgical ablation of atrial fibrillation, and employment of diastolic support and ventricular assist devices. In many patients a combination of these procedures is required to address the multiple pathophysiologic components of CHF. As techniques are refined and more data become available, the results of surgical treatment of heart failure are likely to improve. In addition, advances in innovations such as gene therapy, cell therapy and engineered artificial myocardial tissue will hopefully bring additional benefits to this problematic therapy over the next few years. In this review we discuss the characteristics of the most common surgical techniques for reversing left ventricular remodeling. |
9,382 | Noninvasive risk stratification prevents sudden death due to paroxysmal atrial fibrillation in hypertrophic cardiomyopathy. | Sudden death is a tragic complication of hypertrophic cardiomyopathy. We report the case of a young patient with hypertrophic cardiomyopathy in whom an episode of atrial fibrillation triggered ventricular fibrillation and cardiac arrest. A 21-year-old man with nonobstructive hypertrophic cardiomyopathy underwent cardioverter-defibrillator implantation for primary prevention of sudden death, after risk stratification with noninvasive strategies. After 6 weeks, during a moderate effort, the patient had a syncopal episode, preceded by palpitations and dizziness, and terminated by the cardioverter-defibrillator. Device interrogation revealed an episode of atrial fibrillation with high ventricular response, spontaneously followed by ventricular tachycardia/fibrillation. Atrial fibrillation is a potential trigger of life-threatening arrhythmias and sudden death in patients with hypertrophic cardiomyopathy. Clinical investigation of risk markers for sudden death should be encouraged to identify high-risk patients who may benefit from a prophylactic therapy with an implantable cardioverter-defibrillator. |
9,383 | Successful reoperation after 17 years in a case of endomyocardial fibrosis. | Endomyocardial fibrosis is an uncommon cause of congestive cardiac failure characterized by severe diffuse thickening of the endocardium, and the overall long-term prognosis of this disease is generally considered poor. We report a case of endomyocardial fibrosis that was initially treated by endocardial resection and mitral valve replacement, which was regularly followed-up. The patient underwent successful repair of a paravalvular leak after a period of 17 years. The treatment of left ventricular endomyocardial fibrosis with associated mitral valve disease by endocardial resection and mitral valve replacement is a good surgical option that provides good long-term results. |
9,384 | "Initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia supplemented with potassium and magnesium for hypertrophied hearts. | Hypertrophied hearts are subject to the deleterious effects of intraoperative ischemia-reperfusion, and stable maintenance of myocardial cardioplegic arrest is essential. Continuous cardioplegia infusion appears an ideal modification to overcome this issue, except for a large amount of crystalloid solution infused into the myocardium. We previously introduced "initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia (mini-BCP) supplemented with potassium and magnesium, and this study was designed to elucidate its efficacy in patients with hypertrophied hearts.</AbstractText>Thirty patients (M:F=17:13, 69.2+/-7.8 years) with left ventricular mass index greater than 150 g/m(2) who underwent aortic valve replacement between 1996 and 2002 were enrolled, and were allocated to one of the two groups. The same infusion protocol was used for both groups as follows: initial and intermittent (every 20 min) BCP was antegradely infused for 2 min at the rate of 200 mL/min, and continuous retrograde BCP flow rate was set at 60-100mL/min. Group C (n=15) received 4:1-diluted BCP modified with Buckberg solution, and Group M (n=15) were given mini-BCP supplemented with potassium (initial/others: 15.4/9.8 mEq/L) and magnesium (initial/others: 6.5/4.0 mEq/L).</AbstractText>Stable cardioplegic arrest was maintained in all study patients, and total amount of crystalloid solution as cardioplegia was lesser in Group M (79.4+/-27.5 mL) than in Group C (937.3+/-372. 1mL, p<0.01). Group M showed a higher incidence of spontaneous heartbeat recovery after aortic unclamping (13 versus 6, p<0.05) and a lower incidence of postoperative atrial fibrillation (0 versus 5, p<0.05). Postoperatively, maximum dopamine dose (3.35+/-2.27 microg/kg/min versus 5.49+/-2.30 microg/kg/min, p<0.05) and peak plasma creatine kinase-myocardial band (CK-MB) (21.7+/-7.2 IU/L versus 28.8+/-8.4 IU/L, p<0.05) were lower in Group M. Early postoperative echocardiography revealed a lower incidence of paradoxical ventricular septal motion (M versus C; 3 versus 10, p<0.05) and greater left ventricular ejection fraction (M versus C; 70.7+/-4.0% versus 67.0+/-5.3%, p<0.05) in Group M.</AbstractText>These results suggest that "initial, continuous and intermittent bolus" administration of mini-BCP, supplemented with potassium and magnesium, is a novel modification for patients with hypertrophied hearts in terms of simplifying the maintenance of cardioplegic arrest with beneficial myocardial protective effects.</AbstractText> |
9,385 | The role of automated external defibrillators in dental practice. | Dental practices are seeing an increasing number of elderly and medically compromised patients, making it likely that staff will be called upon to respond to medical emergencies in the office, including cardiac arrest. Out-of-hospital cardiac arrests account for nearly half of all cardiovascular deaths in the United States. In adult cardiac arrest victims, the most frequent cause of sudden cardiac arrest is ventricular dysrhythmia, either ventricular tachycardia or ventricular fibrillation. The survival rate for sufferers of out-of-hospital cardiac arrests is a dismal 1% to 5% to hospital discharge. A majority of people who survive to discharge sustain significant morbidity. Untreated ventricular fibrillation degenerates into asystole, which is often refractory to resuscitative efforts and represents a terminal event. The development and availability of the automated external defibrillator (AED) represents a promising advance in the pre-hospital early defibrillation of victims of sudden cardiac arrest in a variety of settings, often remote from hospitals or EMS personnel. Given the medically compromised segment of the population treated in many dental practices today, it is imperative that dental practitioners and allied health providers become trained in the recognition and prompt initiation of emergency care, including basic life support with early defibrillation. The AED is becoming more accessible, with increasingly widespread availability, training in its use and relative ease of operation, making the goal of increased survival one in which dental health professionals can play a part. |
9,386 | Pregnancy outcomes after atrial repair for transposition of the great arteries. | Increasingly, women born with complete transposition of the great arteries who have undergone atrial repair by either the Senning or the Mustard procedure are reaching childbearing age. This study reports on pregnancy outcomes after the atrial repair of transposition of the great arteries. Record review and standardized questionnaires were used to ascertain the outcomes of 70 pregnancies reported in 40 women (36 Mustard procedures, 4 Senning procedures). Of the 70 pregnancies, 54 resulted in 56 live births, 10 in miscarriages, and 6 in therapeutic abortions. At pregnancy, 31 women were in New York Heart Association class I, 8 were in class II, and 1 was in class III. Thirty-nine percent of the infants were delivered prematurely and weighed 2,714 +/- 709 g; 28% were delivered by cesarean section, 8 for cardiac indications. Maternal complications included arrhythmias in 5 women and hemoptysis in 2 women. Heart failure occurred in 6 women, developing during the second and third trimesters. Postpartum cardiac events developed 2 to 9 days postpartum: heart failure in 5 women, atrial fibrillation in 1 woman, and decreased oxygen saturation due to a new atrial baffle leak in 1 woman. Severe right ventricular (RV) failure led to cardiac transplantation after delivery in 1 woman; another developed heart failure and then died suddenly 1 month after delivery. There was 1 late death, 4 years after the patient's last pregnancy. In conclusion, pregnancy after atrial repair carries a moderate degree of risk and should be undertaken with caution. |
9,387 | Characteristics of ventricular tachyarrhythmias occurring in ischemic versus nonischemic patients implanted with a biventricular cardioverter-defibrillator for primary or secondary prevention of sudden death. | The InSync ICD Registry evaluated patients indicated for cardiac resynchronization therapy with defibrillation.</AbstractText>Cardiac resynchronization therapy with defibrillation systems are prescribed for both primary and secondary prevention of sudden cardiac death in patients with heart failure with both ischemic and nonischemic etiology. The characterization of ventricular tachyarrhythmias detected by the ICD is not well known in these subpopulations.</AbstractText>We enrolled 421 patients with symptomatic heart failure despite optimized medical treatment, ventricular dyssynchrony, and primary or secondary ICD indications. An electrophysiologist reviewed all spontaneous episodes. Patients were grouped by etiology and ICD indications.</AbstractText>The 421 patients included 292 ischemic (159 primary prevention) and 129 nonischemic (68 primary prevention) patients. In 19 +/- 11 months of follow-up, 110 patients (63 ischemic, 30 primary prevention and 47 nonischemic, 21 primary prevention) presented ventricular tachyarrhythmias, occurring in a ventricular tachycardia (VT) or a ventricular fibrillation zone (1382 and 456 events, respectively). The incidence of overall ventricular tachyarrhythmias in nonischemic patients in secondary prevention (35.7% at 1 year) was higher than in ischemic patients implanted for either indication (16.5% and 22.9% at 1 year, respectively). The incidence of self-terminating ventricular tachyarrhythmias was greater in patients with nonischemic heart disease, regardless of indication. Patients with ischemic heart disease in primary prevention had a lower occurrence of VTs, whereas nonischemic patients in primary prevention had faster VTs.</AbstractText>Both rate of occurrence and characteristics of detected ventricular tachyarrhythmias vary according to underlying etiology and indication. Therefore, different device programming according to patient's profile is advisable to improve ventricular tachyarrhythmias management.</AbstractText> |
9,388 | RAte Control Efficacy in permanent atrial fibrillation: a comparison between lenient versus strict rate control in patients with and without heart failure. Background, aims, and design of RACE II. | Recent studies demonstrated that rate control is an acceptable alternative for rhythm control in patients with persistent atrial fibrillation (AF). However, optimal heart rate during AF is still unknown.</AbstractText>To show that in patients with permanent AF, lenient rate control is not inferior to strict rate control in terms of cardiovascular mortality, morbidity, neurohormonal activation, New York Heart Association class for heart failure, left ventricular function, left atrial size, quality of life, and costs.</AbstractText>The RACE II study is a prospective multicenter trial in The Netherlands that will randomize 500 patients with permanent AF (< or = 12 months) to strict or lenient rate control. Strict rate control is defined as a mean resting heart rate < 80 beats per minute (bpm) and heart rate during minor exercise < 110 bpm. After reaching the target, a 24-hour Holter monitoring will be performed. If necessary, drug dose reduction and/or pacemaker implantation will be performed. Lenient rate control is defined as a resting heart rate < 110 bpm. Patients will be seen after 1, 2, and 3 months (for titration of rate control drugs) and yearly thereafter. We anticipate a 25% 2.5-year cardiovascular morbidity and mortality in both groups.</AbstractText>Enrollment started in January 2005 in 29 centers in The Netherlands and is expected to be concluded in June 2006. Follow-up will be at least 2 years with a maximum of 3 years.</AbstractText>This study should provide data how to treat patients with permanent AF.</AbstractText> |
9,389 | Implant of a biventricular pacemaker in a patient with dextrocardia and persistent left superior vena cava. | Congenital anomalies of the heart can pose challenges to cardiac invasive procedures. Here, we present the case of a 40-year-old man with the combination of dextrocardia, a persistent left superior vena cava, and idiopathic dilated cardiomyopathy. We describe the successful implantation of a biventricular pacemaker-defibrillator under this complex anatomic condition. |
9,390 | Avoidance of electromagnetic interference to implantable cardiovertor-defibrillator during atrioventricular node ablation for atrial fibrillation using transvenous cryoablation. | Transient or permanent malfunction of implantable device may result from electromagnetic interference during delivery of radiofrequency energy for treatment of cardiac arrhythmias. Therefore, there is a clinical need for an alternative energy source for cardiac arrhythmia ablation in patients with implantable device. This report presents a case of the absence of electromagnetic interference to an implantable cardioverter defibrillator during atrioventricular nodal ablation for atrial fibrillation to avoid inappropriate shock. |
9,391 | Present understanding of shock polarity for internal defibrillation: the obvious and non-obvious clinical implications. | Uncertainty about the best electrode configuration has combined with the programming flexibility in modern implantable cardioverter-defibrillators (ICDs) to result in routine polarity reversal during an implant to deal with a high defibrillation threshold (DFT). We feel that this practice is not always supported by the clinical data and the present scientific understanding of defibrillation.</AbstractText>A meta-analysis of the clinical studies on ICD shock polarity was performed. Subgroup analyses were also performed to test the impact of high DFTs, various tilts, and the use of the hot can electrode. A review of the basic research surrounding the effects of polarity in defibrillation is also presented.</AbstractText>A total of 224 patients were studied. The use of an anodal right ventricular (RV) coil lowers the mean DFT by 14.8% (P = 0.00001). It provides thresholds equal to or lower than cathodal defibrillation in 83% of patients. The fraction of patients with lower anodal DFTs was 94/224 versus 38/224 for cathodal polarity. This phenomenon may be explained by virtual electrode effects. In particular, anodal electrodes tend to produce collapsing wavefronts while cathodal electrodes tend to produce expanding proarrhythmic wavefronts.</AbstractText>In an ICD implant, the RV coil should be the anode. Furthermore, DFT testing beginning with cathodal defibrillation is most likely unnecessary and needlessly extends the procedure's duration and increases the risks for the patient.</AbstractText> |
9,392 | Role of rate control and regularization through pacing in patients with chronic atrial fibrillation and preserved ventricular function: the VRR study. | High heart rates in chronic atrial fibrillation (CAF) is one of the factors responsible for hemodynamic alterations and may lead to tachycardiomyopathies. The ventricular rate regulation (VRR) study evaluates the effect of ventricular rate regularization in CAF patients with preserved ventricular function, marked ventricular rate variability, and indications for pacemaker (PM) implantation owing to symptomatic pauses. Rate regularization was achieved using VRR algorithm (INSIGNIA pacemakers, Guidant Corp., St. Paul, MN, USA).</AbstractText>One month after PM implantation, 58 patients followed two 3-month crossover periods (VRR-OFF; VRR-ON) in which the VRR algorithm was randomized and compared to fixed rate stimulation at 60 ppm. During follow-up visits a 6-minute walk test was performed under partially inhibited conditions (PM at 40 ppm) and ventricular response was recorded. The following parameters were measured: mean ventricular rate (MR), rate variability (RR30), rate recovery after exercise (SLOPE = (R-END - R-REC)/(R-END - 40)), R-END being the rate at end of walk and R-REC the rate 1 minute after exercise.</AbstractText>The VRR algorithm decreased rate variability (RR30: -7.36 +/- 8.8; P < 0.01) without increasing ventricular rate (MR: -1.11 +/- 8.3 P = NS), while SLOPE improved significantly (SLOPE: +15.41 +/- 16.8 P < 0.01).</AbstractText>VRR effectively stabilizes rate, without increasing pacing rate above spontaneous rhythm and helps achieve a more favorable autonomic balance, improving rate recovery after exercise.</AbstractText> |
9,393 | Inappropriate ICD therapy: does device configuration make a difference. | Inappropriate implantable cardioverter defibrillator (ICD) therapy (IT) is a common complication in patients with ICD. IT is commonly triggered by supraventricular tachycardias (SVT). Dual chamber ICDs (D-ICDs) may distinguish SVT from ventricular tachycardia/ventricular fibrillation better than single chamber ICDs (S-ICDs) and may be associated with a smaller incidence of IT.</AbstractText>We reviewed the charts of 386 patients who had an ICD implanted for an AHA class I indication. Intracardiac electrograms were used to classify shocks as either appropriate or inappropriate.</AbstractText>Of 295 patients with an S-ICD, 66 (22.3%) received IT, compared to 5 (5.4%) of 91 patients with a D-ICD. The likelihood of being event-free at 1, 2, 3, and 4 years was 96.1%, 96.1%, 96.1%, and 89% for patients with D-ICD and 80.7%, 72.7%, 69.6%, and 66.4%, respectively, for patients with S-ICD (P < 0.001). Multivariate analysis showed no significant association with age, sex, history of atrial fibrillation, history of hypertension, or ejection fraction. SVTs were the commonest cause of IT in our patients.</AbstractText>Patients with D-ICD are less likely to receive IT as compared to patients with S-ICD.</AbstractText> |
9,394 | Omega-3 fatty acids and hypertension in humans. | 1. Population studies and clinical trials provide compelling evidence that omega-3 (omega3) fatty acids have cardioprotective effects. The strongest evidence is from DART and GISSI-P, two secondary prevention trials in patients with previous myocardial infarctions. Data from these trials support a reduction in ventricular fibrillation as a primary mechanism for the decreased incidence of myocardial infarction. 2. Evidence suggests that w3 fatty acids may also provide protection against stroke, particularly ischaemic stroke. 3. The cardioprotective effects of omega3 fatty acids relate to improvements in blood pressure, cardiac function, arterial compliance and vascular function, as well as improved lipid metabolism, antiplatelet and anti-inflammatory effects. 4. Clinical trials in humans have shown that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have different haemodynamic properties. Docosahexaenoic acid may be more favourable in lowering blood pressure and heart rate, as well as improving vascular function. However, the effects of EPA and DHA may also differ depending on the target population. |
9,395 | Nupafant, a PAF-antagonist prototype for suppression of ventricular fibrillation without liability for QT prolongation? | PAF antagonists inhibit ischaemia-induced ventricular fibrillation (VF) in animals. However, unfavourable ancillary actions (on QT interval and coronary flow) have been reported with the PAF antagonist, BN-50739. If these are class actions, they would preclude development of PAF antagonists as novel anti-VF drugs. Our purpose was to examine this proposition using the hitherto untested PAF antagonist, nupafant.</AbstractText>Two rat heart preparations (Langendorff and 'dual coronary' perfusion) were used to assay nupafant's effects on ischaemia-induced VF, coronary flow and QT interval, and to test for the site-selectivity necessary if any effects on VF are caused by PAF antagonism.</AbstractText>Global (whole-heart) delivery of 10 microM nupafant, reduced the incidence of ischaemia-induced VF and widened QT interval without affecting coronary flow. Importantly, lower concentrations (0.1 and 1 microM) had no effect on VF, yet widened QT almost identically to 10 microM nupafant. When nupafant was delivered selectively to (and entrapped within) the involved region it partially protected against VF (P<0.05). This occurred without change in QT interval. Selective nupafant delivery to the uninvolved region was without effect.</AbstractText>Nupafant protects against ischaemia-induced VF primarily by site-selective actions in the ischaemic region but, unlike BN-50739, the effect is unrelated to its QT widening action, and is not compromised by any effect on coronary flow. This establishes proof of concept that VF suppression by PAF antagonism need not invariably be associated with QT prolongation or vasodilatation, justifying further development of this drug class.</AbstractText> |
9,396 | Brief sympathetic activation precedes the development of ventricular tachycardia and ventricular fibrillation in hibernating myocardium. | Hibernating myocardium develops inhomogeneity in myocardial sympathetic innervation with spontaneous sudden cardiac death (SCD) because of ventricular fibrillation (VF). The triggers and prodromal arrhythmias initiating SCD in this substrate are unknown.</AbstractText>Swine chronically instrumented with a proximal left anterior descending coronary artery stenosis underwent placement of an implantable telemetry unit capable of continuously recording digitized electrocardiogram and left ventricular pressure signals at 1 kHz in conscious unrestrained animals for periods of up to 5 months.</AbstractText>Spontaneous SCD (n = 10) was initiated by a close-coupled premature ventricular contraction followed by ventricular tachycardia (VT) that degenerated into VF during brief sympathetic activation. Peak heart rates were similar in animals that developed SCD vs survivors (250 +/- 12 vs 261 +/- 6 bpm). Electrocardiogram evidence of ischemia preceding VT/VF occurred in only 1 animal, and there was no significant infarction.</AbstractText>Spontaneous VT/VF in hibernating myocardium develops during brief sympathetic activation with only rare evidence of acute ischemia. This supports the notion that the regional remodeling accompanying hibernating myocardium may be a novel substrate for the development of SCD in chronic ischemic heart disease.</AbstractText> |
9,397 | Antiarrhythmic effects of omega-3 fatty acids. | Fish oil, and omega-3 fatty acids in particular, have been found to reduce plasma levels of triglycerides and increase levels of high-density lipoprotein in patients with marked hypertriglyceridemia, and a pharmaceutical-grade preparation has recently received approval from the US Food and Drug Administration to market for this purpose. However, in both bench research studies and clinical trials, evidence for clinically significant antiarrhythmic properties has also been detected in association with omega-3 fatty acid intake. Arguably the most significant finding in this data set was the reduction in the incidence of sudden death in survivors of myocardial infarction in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione trial and the subsequent recommendation for administration of fish oil as part of the postinfarction regimen in Europe. This article reviews in detail the basic and clinical research studies of fish oil as an antiarrhythmic entity, the forms of preparation and/or administration that appear to possess these properties and those that do not, the types of arrhythmias (ventricular ectopy and atrial fibrillation as well as ventricular tachyarrhythmias) that have been beneficially affected by fish oil administration, and the presumed and known mechanisms by which the beneficial actions are exerted. |
9,398 | Effect of atrial fibrillation on plasma NT-proBNP in chronic heart failure. | Brain natriuretic peptides are elevated in patients with systolic heart failure (HF) as well as in patients with atrial fibrillation (AF) and normal left ventricular ejection fraction (LVEF) and are strong predictors of death in HF patients. The aim of our study was to examine the levels of N-terminal pro brain natriuretic peptide (NT-proBNP) in patients with HF and AF versus HF and sinus rhythm (SR) and if NT-proBNP has prognostic influence in patients with AF.</AbstractText>We included 245 patients (72% men, 70 years) with HF referred to a HF clinic. NT-proBNP was measured at referral (baseline).</AbstractText>At baseline, 26% had AF and at follow-up 35% of the surviving patients. Patients with AF were older than patients with SR (p=0.009), but LVEF and NYHA distribution were similar. Median NT-proBNP levels were higher: 2528 vs. 899 pg/ml (p<0.001). NT-proBNP was significantly correlated with AF at baseline (p<0.001), age (p=0.001), P-creatinine (p<0.001) and reduced LVEF (p=0.002). NT-proBNP was an independent predictor of death in patients with AF, adjusted HR 4.0 (95% CI 1.6-10.2) (p=0.003).</AbstractText>NT-proBNP levels are higher in HF patients with AF than in HF patients with SR and has prognostic value despite the presence of AF.</AbstractText> |
9,399 | Inappropriate implantable cardioverter-defibrillator discharges unrelated to supraventricular tachyarrhythmias. | The development of implantable cardioverter-defibrillators (ICDs) with QRS morphology discrimination and dual-chamber sensing capabilities has improved the differentiation of supraventricular from ventricular tachycardias (VTs). Inappropriate ICD discharges may result from extracardiac signals caused by electromagnetic interference (EMI), because of electric fields and leakage currents from domestic or medical electrical devices, damaged sensing leads, and various cardiac and extracardiac signals that mimic VT and/or ventricular fibrillation. The aim of our study was to determine retrospectively the incidence and clinical relevance of these ICD behaviours and offer possible therapeutic solutions.</AbstractText>We have observed inappropriate discharges unrelated to supraventricular arrhythmias in 13 (3.9%) of the 336 patients implanted with ICDs in our centre from 1989 to 2005. Seven patients received inappropriate shocks following exposure to external EMI: improperly grounded electric stove, electrically powered watering system, hydro-massage bath, electrical pruner, electrocautery current during cardiac surgery, transcutaneous electric nerve stimulation. In four patients, spurious discharges were related to internal noise of the ICD system from inappropriate lead connections. In two cases, erroneous antitachycardia therapy was delivered following different body signals oversensing (T-wave oversensing, wide QRS double-counting and myopotentials). In nine patients, non-invasive solutions prevented further inappropriate therapies (avoidance of EMI, malfunctioning atrial lead exclusion, ventricular sensing reprogramming). In four patients, surgical revision of the system was required (lead connections or position revision).</AbstractText>In our experience, inappropriate ICD discharges unrelated to supraventricular arrhythmias occurred in about 4% of ICD patients. A careful evaluation of clinical data and telemetric information (lead impedance, sensed R-wave, stored electrograms) is essential in order to understand the nature of inappropriate ICD discharges and to select the most appropriate solution.</AbstractText> |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.