Serum creatine kinase activity and sensing characteristics after intraoperative arrhythmia induction using implantable defibrillator rate sensing leads.

In 29 patients (24 men, 5 woman, mean age 57 +/- 14 years) we evaluated the effect of intraoperative arrhythmia induction during implantable defibrillator (ICD) placement using alternating current (AC) applied through the epicardial rate sensing leads on acute and chronic pacing thresholds, electrogram amplitudes, slew rates and serum creatine kinase levels. In 15 patients undergoing new ICD implantation, pacing thresholds, electrogram amplitudes, slew rates, and resistances were measured before and following at least three inductions of ventricular fibrillation (VF) using AC applied through the epicardial rate sensing leads. Fourteen patients who underwent VF induction using AC through the epicardial leads during initial implant (mean time of 31 months previously) underwent ICD pulse generator replacement only with parameters measured as above before and after at least two inductions, and these compared to the values at initial implant. In all 29 patients serum creatine kinase levels were obtained before, immediately following, and at 8, 16, and 24 hours after surgery. No significant change in acute pacing threshold, electrogram amplitude, slew rate or resistance occurred. Chronically there was an expected 154% increase in pacing threshold but no significant change in electrogram amplitude or resistance. Serial serum creatine kinase and MB isoenzyme determinations demonstrated no evidence of myocardial necrosis. We conclude that intraoperative arrhythmia induction during ICD implantation using AC applied through the rate sensing leads is a safe and effective technique.