Correlates of reperfusion ventricular fibrillation in dogs

To elucidate determinants of reperfusion ventricular fibrillation (VF), regional myocardial blood flow, ATP, creatine phosphate (CP), heart rate and blood pressure were compared in 2 groups of anesthetized dogs: those that fibrillated spontaneously upon release of a 15-minute coronary artery occlusion (VF group, n = 8) and those that did not fibrillate when reperfused (No VF group, n = 27). Arterial pressure and heart rate before and during coronary artery occlusion were similar in both groups. Ischemie endo- and epicardial ATP values, measured at the end of the occlusion period, were reduced approximately 20% of nonischemic values in both groups. In contrast, CP (nmohmg protein^-1) within the ischemie zone was significantly lower in the VF group in both the epicardium (14.3 ± 1.6 in the VF group vs 22.8 ± 2.5 in the No VF group, p < 0.01) and the endocardium (9.0 ± 2.0 in the VF group vs 18.7 ± 1.8 in the No VF group, p < 0.01). Furthermore, epi- and endocardial regional myocardial blood flow in the center of the ischemic zone during occlusion was significantly lower in VF dogs than in No VF dogs. Epicardial flow was 0.06 ± 0.03 ml·min^-1·g^-1in VF dogs vs 0.44 ± 0.06 in No VF dogs (p < 0.001) and endocardial flow was 0.03 ± 0.02 ml·min^-1·g^-1 in VF dogs vs 0.23 ± 0.04 ·ml-min^-1·g^-1 in No VF dogs (p < 0.001). These data suggest that low levels of regional myocardial blood flow and CP during coronary artery occlusion are associated with an increased risk of VF on reperfusion. Thus, the severity of ischemia in the center of the ischemie zone may be a determinant of reperfusion VF.