Effect of collateral flow on ventricular arrhythmia during acute myocardial ischemia and reperfision

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In acutely ischemic nanine hearts, the incidence of ventricular arrhythmia is related to the development of collateral flow. Thus, we examined the effect of collateral flow on ventricular arrhythmia during acute myocardial ischemia and reperfusion.1)When dogs with poor development of collateral flow were used, pre-existing coronary stenosis caused the development of collateral flow and reduced the incidence of ventricular arrhythmia during subsequent occlusion.2)The technique of retrograde blood flow(RBF)decreases collateral flow into the ischemic myocardium, and to cause severe myocardial ischemia in dogs. During retrograde blood flow, the severity of ischemia was great, and the incidences of ventricular premature beats and ventricular tachycardia(VT)were high, but that of ventricular fibrillation(VF)was not high. Thus, RBF can be used to examine occulusive and reperfusion ventricular arrhythmia in dogs.3)When the antecedent ischemia was 10 min RBF, reperfusion VF was not prevented by partial reperfusion.4)We examined the electrophysiologic changes before an onset of ventricular tachyarrhythmias during partial reperfusion followina 20 min RBF. During partial reperfusion, slight improvement in fractionation induced sustained VT, and an occurrence of new deflections induces non-sustained VT degenerating VF.