Sequential pulse internal defibrillation: is there an advantage to "switched" current pathways?
Sequential pulse internal defibrillation delivered via orthogonal current pathways has been postulated to improve defibrillation efficacy. The efficacy of twin truncated exponential sequential shocks was compared in four different defibrillation electrode configurations in six pentobarbital-anesthetized, open-chest dogs. Lead systems consisted of the conventional single current pathway spring-patch and patch-patch electrode configurations, as well as a multiple patch lead configuration, which utilized either a single (multiple patch-unswitched) or two different (multiple patch-switched) current pathways. Curves of percent successful defibrillation versus initial voltage and energy were constructed and the data were analyzed by logistic regression. The energy and initial voltage required for 50% successful defibrillation (E50 and V50, respectively) for each lead system were then compared. The E50 for the multiple patch-unswitched and switched lead systems (4.3 +/- 1.5 J and 4.6 +/- 1.7 J, respectively) were significantly lower than for the spring-patch (9.0 +/- 3.1 J; p less than .005) and patch-patch (6.6 +/- 1.2 J; p less than .005) lead systems. In addition, the V50 for the multiple patch-unswitched lead configuration (270.6 +/- 48.4 V) was significantly lower than that of all other lead systems (p less than .005). Therefore lead configurations utilizing multiple patch electrodes improve defibrillation efficacy over conventional lead systems, but there is no advantage to "switched" current pathways.
Fain
E S
ES
Division of Cardiology, Stanford University Medical Center, CA 94305.
Sweeney
M B
MB
Franz
M R
MR
D000818:Animals; D004285:Dogs; D004553:Electric Conductivity; D004554:Electric Countershock / Q000379:methods*; D004560:Electricity; D004566:Electrodes; D005260:Female; D008297:Male; D013997:Time Factors