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Amiodarone is an antiarrhythmic agent known to cause prolongation of action potential duration which is reflected in the electrocardiogram as a prolongation of the QT interval. Prolongation of the QT interval in patients dying suddenly was compared with that in patients who remained alive to determine whether a difference existed between these two groups. The electrocardiogram and amiodarone levels were evaluated in 33 patients who presented with cardiac arrest and symptomatic ventricular tachycardia in whom no other antiarrhythmic agent was found effective in preventing induction of ventricular tachycardia during electrophysiologic studies. There were 30 men and 3 women (mean age 52 +/- 10 years). Twenty-three are alive after a mean follow-up period of 12 +/- 7 months. Ten died: six suddenly, three of non-cardiac causes and one of congestive heart failure. Using a two-way analysis of variance, the percent change in QT, QTc, JT and JTc intervals before and after amiodarone therapy was analyzed. Marked prolongation in the QT interval was present in patients who remained alive with amiodarone therapy. A significant difference in percent QT prolongation was seen between the latter patients and those who died suddenly (p less than 0.005). No difference was observed in the percent change in QRS interval between the two groups. The levels of amiodarone (2.5 versus 3.2 micrograms/ml) and its metabolite (desethylamiodarone) were not significantly different between the living patients and those who died suddenly. These findings suggest that a prolongation of the QT interval may be a marker for the therapeutic antiarrhythmic effect of amiodarone.

Abstract:Background: Reports in the literature indicate that specialty clinics focusing on management of patients with specific chronic disorders have a significant positive impact on patient outcomes. Atrial fibrillation (AF), one of the most common forms of cardiac arrhythmia, affects millions of patients. Outcome data regarding the impact of managing patients with AF are limited. We established a specialty clinic focusing on management of patients with AF. The objective of our study was to evaluate the outcomes of treating AF patients in this clinic.Methods: A team consisting of electrophysiologists and pharmacists designed a specific plan for managing and educating patients. This plan consisted of evaluation, implementation of an individualized treatment plan, patient education, medication management, and follow-up care. We reviewed the outcomes of patients who had clinic visits between November 2011 and March 2012. The primary outcome was the incidence of AF-related hospitalizations and stroke.Results: Seventy one patients were included in the analysis. Out of 71 patients, we identified 17 (23.9%) patients who were hospitalized. Two of these 17 hospitalized patients had ischemic stroke events. Conclusion:When compared to published data in the existing literature, managing AF patients in specialty clinics reduces the incidence of AF-related hospitalizations and stroke.

This study was undertaken to assess the incidence, indications, and predisposing factors for pacemaker placement in a pediatric heart transplant population. From November 1985 to May 1994, 246 pediatric patients have undergone cardiac transplantation at Loma Linda University Medical Center. Seven (2.8%) have received pacemaker placement with an 8-50 month follow-up period. Median age at transplant was 462 days (0 days to 2.5 years). The median time to pacemaker placement was 190 days (18-1,672 days) after transplantation. Indications were sick sinus syndrome (SSS) in 5 and heart block in 2 patients (1 during acute rejection). Three patients with SSS underwent electrophysiology studies (EPS); 1 was normal and 2 showed sinus node dysfunction. The mode of pacing was VVIR in 6 patients and VVI in 1 patient. All 6 survivors are doing well and 5 patients' pacemakers still provide support. These 7 patients were compared with 185 pediatric patients (0 days to 12-years-old) transplanted during 1985 through 1993 who survived at least 6 months after transplantation. There was no correlation between the receipt of a pacemaker and graft cold ischemic time, rejection history, donor age, or recipient age at transplantation. The 5 patients with SSS had significantly lower average heart rates in the first month after transplantation (108 +/- 16 vs 130 +/- 12; P = 0.0002). The need for permanent pacemakers in this population is uncommon. Pacemakers, however, can be safely performed when necessary with excellent clinical results.

Patients needing an implantable cardioverter defibrillator (ICD) system, but without suitable access from jugular or subclavian routes present a vexing problem. Such patients would normally undergo thoracotomy for epicardial lead placement. However, for patients who decline such an intervention, there have been no alternatives for them. There is scarce data from the published literature addressing this dilemma. We report two cases of successful ICD and biventricular ICD placement from an ileofemoral approach.

Certain groups are known to have an increased risk for sudden cardiac death. Epidemiologic studies have suggested that patients with atrial fibrillation may be at higher risk. The authors hypothesize that atrial fibrillation may increase myocardial vulnerability. To test this hypothesis, 37 dogs were studied using programmed electrical stimulation techniques to determine myocardial vulnerability as assessed by the ability to provoke ventricular tachycardia. Prior to atrial fibrillation, programmed electrical stimulation did not induce ventricular tachycardia. Aconitine was then topically applied to the right atrial appendage with care taken not to make contact with the ventricle. Application of aconitine caused atrial fibrillation with an increase in ventricular rate, but did not affect arterial blood pressure. Ventricular tachycardia was induced by programmed electrical stimulation studies in 25 of 26 dogs in atrial fibrillation. The enhanced vulnerability was noted following atrial fibrillation, not after aconitine application to the great veins, which did not cause atrial fibrillation. To further exclude the possibility that aconitine application may cause changes in ventricular threshold, atrial fibrillation was induced by pacing techniques in five dogs. Prior to atrial fibrillation induction, programmed electrical stimulation did not induce ventricular tachycardia. Following atrial fibrillation, ventricular tachycardia could be repeatedly induced. Mean heart rate following atrial fibrillation increased, while pacing animals at this increment in rate did not change the noninducibility of dogs in sinus rhythm. Six patients with a history of atrial fibrillation and ventricular tachycardia were studied to determine if AF lowered myocardial threshold to VT induction. Ventricular tachycardia could only be induced by PES techniques in four of five patients when the patients' rhythm was AF (P < 0.05). This study suggests that atrial fibrillation lowers myocardial threshold for ventricular tachycardia induction and thus enhances myocardial vulnerability. The association of AF with a higher incidence of sudden death may be due to an enhanced electrical instability.

Background:Reports in the literature indicate that specialty clinics focusing on management of patients with specific chronic disorders have a significant positive impact on patient outcomes. Atrial fibrillation (AF), one of the most common forms of cardiac arrhythmia, affects millions of patients. Outcome data regarding the impact of managing patients with AF are limited. We established a specialty clinic focusing on management of patients with AF. The objective of our study was to evaluate the outcomes of treating AF patients in this clinic.Methods:A team consisting of electrophysiologists and pharmacists designed a specific plan for managing and educating patients. This plan consisted of evaluation, implementation of an individualized treatment plan, patient education, medication management, and follow-up care. We reviewed the outcomes of patients who had clinic visits between November 2011 and March 2012. The primary outcome was the incidence of AF-related hospitalizations and stroke. Results:Seventy one patients were included in the analysis. Out of 71 patients, we identified 17 (23.9%) patients who were hospitalized. Two of these 17 hospitalized patients had ischemic stroke events. Conclusion:When compared to published data in the existing literature, managing AF patients in specialty clinics reduces the incidence of AF-related hospitalizations and stroke.