Effects of residual stenosis on infarct size and regional transmural myocardial blood flow after reperfusion.

This study in dogs was designed to determine the effects of residual stenosis on infarct size and on the transmural distribution of coronary flow in the central and peripheral ischemic perfusion bed. A plastic shunt containing a Doppler flow probe was inserted between the left anterior descending coronary artery and the subclavian artery. The dogs were divided into two groups. Group 1 (N = 7) underwent total shunt occlusion for 2 hours followed by reperfusion at 50% of control flow for 2 hours. Group 2 (N = 8) underwent 2 hours of total occlusion followed by 2 hours of total reperfusion. Regional blood flow was measured by radiolabeled microspheres, and infarct areas were quantitated with triphenyl tetrazolium chloride staining. Infarct sizes expressed as a percentage of the left ventricle or as a percentage of perfusion territory were significantly (p less than 0.05) smaller in animals with total reperfusion (group 2) than in dogs with partial reperfusion (group 1). Endocardial flows in the central infarct zone were significantly higher in dogs with total reperfusion than was observed with partial reperfusion; epicardial flows were not significantly different. In the peripheral region both endocardial flows and epicardial flows with total reperfusion were significantly higher than with partial reperfusion. These studies suggest that residual stenosis after thrombolysis may increase infarct size and reduce endocardial flow in the central infarct zone and transmural flow in the peripheral zone.