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.


OBJECTIVE
To examine changes following high-energy biphasic shocks delivered by integrated bipolar ICD systems.


METHODS
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.


CONCLUSIONS
It may be necessary to pace at a high-voltage output following biphasic shocks delivered by integrated bipolar ICD systems.
Yamanouchi
Yoshio
Y
Department of Cardiology, Chikushi Hospital, Fukuoka University, Fukuoka, Japan.
Miyoshi
Kei
K
Kodama
Sunao
S
Shiga
Yuhei
Y
Sumi
Shunichiro
S
Niimura
Hideya
H
Toujou
Hideaki
H
Urata
Hidenori
H