Exerimental coronary artery occlusion. III. The determinants of collateral blood flow in acute coronary occlusion.

Coronary collateral blood flow was measured with tracer microspheres in 3 different experimental conditons in the dog heart: 1. after occlusion of a large coronary artery in the in situ beating heart, 2. after occlusion of a small coronary artery in the in situ beating heart and 3. after occlusion of a large coronary artery in the isolated, empty beating, blood-perfused heart. with large coronary artery occlusion in situ, collateral blood flow was very low (5ml/min/100 g). Large coronary artery occlusion in the isolated heart showed a much higher collateral blood flow (25 ml/min/100 g). Small coronary artery occlusion in situ showed a relatively high collateral blood flow (22 ml/min/100 g). Small coronary artery occlusion produced only very small infarcts even when infarct size was expressed as the ratio of infarcted area over the area-at-risk (i.e., perfusion area of the occluded artery). Our experiments showed that acutely available collateral blood flow depends on perfusion pressure, extravascular resistance, size of the area at risk and size, number, and location of collateral vessels.