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.