Increased ventricular pacing thresholds have been observed following monophasic waveform shocks in implantable cardioverter defibrillators (ICDs). This study aimed to examine such changes following high-energy biphasic shocks in ICDs. Method: Ten episodes of VF were induced every 10 minutes in 10 pigs (23,l+-3.0 kg). After 10 seconds of VF a 40J biphasic shock (total 10 shocks) was delivered for successful defibrillation in the true-bipolar sensing lead system of the ICD. Ventricular bipolar pacing thresholds before and after these shocks were evaluated at one-minute intervals. Results: The mean pacing threshold before shock delivered was 0.066+-0.059 uJ. Those of the first,second and third minutes after the first shock were 0.052+-0.061 uJ,0.044+-0.039 irrespectively; showing that pacing thresholds gradually decreased. Conclusion: It may not be necessary to pace at a high-voltage output after biphasic shocks in ICDs.
展开▼
