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Background: Implantable cardioverter defibrillators (ICDs) are an increasingly common treatment for survivors of sudden cardiac arrest or others with life-threatening ventricular arrhythmias. Health-care providers are often reluctant to prescribe exercise for this group because of the belief that it will provoke ventricular arrhythmias and cardiac arrest; patients are often afraid to exercise because of concern over receiving an ICD shock. A social cognitive theory-driven exercise intervention aimed at stabilizing cardiac arrhythmias and reducing ICD shocks by increasing parasympathetic autonomic nervous system control is described. Methods: The exercise intervention has two phases that include an 8-week aerobic conditioning component followed by a 16-week exercise maintenance component. The aerobic exercise intervention is expected to have significant impact on cardiopulmonary function, ventricular arrhythmias, cardiac autonomic function, and self-efficacy in persons who have an ICD. The exercise intervention is currently being tested using a randomized clinical trial format, the results of which will be available in 2012. Conclusion: The exercise after ICD trial is one of the first clinical trials to test the effects of aerobic exercise on cardiopulmonary outcomes after receiving an ICD for primary or secondary prevention of sudden cardiac arrest. (PACE 2010; 973–980) [ABSTRACT FROM AUTHOR]

90-[mu]F and 120-[mu]F Biphasic Pulse Transvenous Defibrillation. Introduction: Capacitance is known to influence defibrillation. Optimal biphasic waveform capacitance for transvenous unipolar defibrillation systems in man is currently being defined. In an effort to improve defibrillation efficacy, we examined the relative defibrillation efficacy of a 65% tilt bipbasic pulse from a 90-[mu]F capacitor compared to a 65% tilt biphasic pulse from a 120-[mu]F capacitor in a prospective, randomized fashion in 16 consecutive cardiac arrest survivors undergoing defibrillator surgery. Methods and Results: The transvenous unipolar pectoral defibriilation system uses a single endocardial RV anodal defibrillation coil and the shell of an 80-cc volume (88 cm² surface area) pulse generator (Medtronic Model 7219C PCD 'active CAN') as the cathode for the first phase of the bipbasic shock: RV+ --> CAN-. Defibrillation thresholds for each capacitance were determined prospectively in a randomized fashion. The defibrillation threshold results for the 90-[mu]F capacitance were: leading edge voltage 383 ± 132 V; stored energy 7.4 ± 5.0 J; and resistance 57 ± 10 ,. The results for the 120-[mu]F capacitance were: leading edge voltage 315 ± 93 V (P = 0.002); stored energy 6.5 ± 3.7 J (P = 0.21); and resistance 57.0 ± 11 (P = 0.87). Conclusions: We conclude that 90-[mu]F, 65% tilt biphasic pulses used with unipolar pectoral defibrillation systems have equivalent stored energy defibrillation efficacy compared to 120-[mu]F, 65% tilt pulses. Use of lower capacitance is possible in present implantable defibrillators without compromising defibrillation. [ABSTRACT FROM AUTHOR]