ABSTRACT
BACKGROUND: Increased ventricular pacing thresholds have been observed following monophasic implantable cardioverter defibrillator (ICD) shocks. AIM: To examine changes following high-energy biphasic shocks delivered by integrated bipolar ICD systems. METHOD: Ten episodes of ventricular fibrillation (VF) were induced at 10 min intervals in nine pigs with integrated ICD systems. After 10 s of each episode of VF, a 40 J biphasic shock was delivered, which successfully terminated VF (a total of 10 shocks). The bipolar pacing threshold at the right ventricular apex was measured before each shock and at 1 min intervals after each shock. RESULTS: The mean pacing threshold was 0.029+/-0.059 muJ before the first shock and gradually increased to 0.14+/-0.10 muJ after the 10th shock. CONCLUSION: It may be necessary to pace at a high-voltage output following biphasic shocks delivered by integrated bipolar ICD systems.
