Coronary reperfusion: effects of vasodilators (papaverine and adenosine).

Reperfusion of a coronary artery is followed by a decline of the myocardial blood flow to both the ischemic (reperfused) and border regions, and the appearance of a transmural flow gradient favoring the epicardium. These findings were ascribed to vascular changes in the reperfused coronary bed. The behavior of the myocardial blood flow was investigated (1) after 4 hours of reperfusion following the intracoronary infusion of vasodilators (papaverine and adenosine) and (2) following the intravenous administration of papaverine during the total period of reperfusion. Intracoronary infusion of vasodilators increased flow (147 per cent) to all the layers of the reperfused myocardium but failed to alter the transmural distribution of flow. The flow response to these vasodilators in the normal vascular bed consisted of a marked increase in flow (385 per cent) and a normal, uniform distribution, suggesting that the development of anatomical vascular changes reduced the capacity of the reperfused vasculature to increase flow, and that these changes were more marked in the endocardial layer. The intravenous papaverine infusion during reperfusion normalized the total flow and its distribution in the zone bordering the reperfused myocardium but not to the ischemic, suggesting perhaps that papaverine may be useful in protecting potentially salvageable myocardium.