Ventricular pacing thresholds following high-energy implantable cardioverter defibrillator shocks in integrated bipolar defibrillation systems

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 μJ before the first shock and gradually increased to 0.14±0.10 μJ 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.