Coronary Revascularization and Implantation of the Automatic Cardioverter/Defibrillator: Reliability of Immediate Intraoperative Testing

Concomitant coronary revascularization and implantation of the automatic cardioverter/defibrillator is an increasingly common procedure. To determine whether cardioversion/defibrillation thresholds measured after weaning patients from cardiopulmonary bypass are sufficient to justify immediate implantation of the pulse generator, we prospectively compared postpump values to those obtained 1 week later in five patients. R-wave amplitudes during both sinus rhythm and ventricular tachycardia, lead impedance, defibrillation thresholds and cardioversion thresholds remained stable or improved from the postpump to the 1 week values. Five other patients had the generator implanted at the time of revascularization. Immediate postbypass cardioversion thresholds (mean 10 +/- 8 joules) in these ten patients did not significantly differ from those of 20 nonpump implantations (VT mean 7 +/- joules; VF 15 +/- 4 joules and defibrillation thresholds mean 17 +/- 6 joules). These findings suggest that the residual effects of cardioplegia, core-cooling and operative ischemia have no significant effects on intraoperative testing of implanted defibrillators. This clinical experience supports the practice of immediate implantation of the pulse generator at the time of revascularization.