Modification of Myocardial Reperfusion by Exogenous Prostacyclin

Abstract

The multiple pharmacologic consequences of the antiplatelet, antithrombotic, and vasoactive effects of exogenous myocardial prostacyclin PGI2 on postischemic reperfusion were studied. In an isolated canine model, 20 hearts underwent one hour of cardioplegia arrest under moderate hypothermia (27-28 ° C) and one hour of no perfusion. Left ventricular function (peak systolic pressure [PSP], rate of rise of left ventricular pressure [dp/dt], compliance), myocardial edema, coronary blood flow, and oxygen content were measured and compared for control and PGI2 groups. While there were no differences in compliance or edema, there was an increase in both myocardial blood flow and oxygen delivery (p=0.025). This modification increased nutritive resuscitation of the ischemic heart during one hour of reperfusion and increased left ventricular function after ischemic arrest (PSP and dp/dt; p=0.04). Myocardial recovery after global ischemia is time-dependent with maximal resuscitation after one hour of supported reperfusion. PGI2 modified this time course by sustaining the coronary vasodilatory effects during the reperfusion hour with increased coronary blood flow, improved oxygen extraction, and enhanced myocardial performance (PSP and dp/dt). PGI2 can play an important role by providing maximal vasodilatory effects to enhance the nutritive recovery of postischemic myocardium.