Treatment of intractable ventricular fibrillation with prompt circulatory support using a biventricular assist device in pigs--an experimental study.

Refractory ventricular fibrillation (VF), intractable to conventional therapy, can be converted into a stable cardiac rhythm by immediate ventricular volume unloading using a form of mechanical circulatory assist (MCA). We investigated the efficacy of MCA in a controlled animal study in which 20 pigs were subjected to intermittent occlusions (5 times) of the left descending coronary artery (5 min. occlusion + 10 min. reperfusion). 12 of the 20 animals (60%) developed 14 events of VF. 64% of VF developed during reperfusion (p less than 0.05). Countershock was attempted up to eight times and was successful in 5 of the 14 events (36%) (primary defibrillation, PD). When conversion was not achieved, total biventricular bypass was instituted. Mean perfusion time between countershock attempts was 24.4 +/- 15.3 min. All animals (n = 9) with cardiac assistance were successfully defibrillated (secondary defibrillation, SD), (p less than 0.05). Hemodynamic parameters after SD were not significantly different from those after PD (p greater than 0.05). Survival rate following PD was 66.6%. Six animals were ultimately weaned from cardiac assistance following SD. Three others died of progressive cardiogenic shock in the six hour follow-up period following SD. These non-survivors had a significantly longer VF time than the survivors (41.7 +/- 10.4 vs. 15.8 +/- 8.0, p less than 0.05). Overall survival after SD was the same as that for PD: 66.6% (p greater than 0.05). These results show that prompt conversion of VF into a stable cardiac rhythm is a prerequisite to recovery.(ABSTRACT TRUNCATED AT 250 WORDS)