Staged reperfusion preserves the coronary flow reserve, especially in the regions not severely damaged by ischemic injury in the canine heart

The objective of this study was to determine the effects of staged reperfusion on the progressive reduction in coronary blood flow (CBF) and coronary flow reserve during reperfusion and on the infarct size in the canine heart. Fifteen dogs underwent 90 min of left circumflex coronary artery occlusion and 3 hr of reperfusion. In the abrupt reperfusion group, the occluder was released completely at the initiation of reperfusion. In the staged reperfusion group, CBF was maintained at 20% of preocclusion values for 10 min after initiation of reperfusion, then gradually released, and completely released 20 min after initiation of reperfusion. There was no significant difference in CBF between the staged (n = seven) and abrupt (n = eight) groups after 3 hr of reperfusion. The repayment of flow debt in the staged reperfusion group was significantly greater than in the abrupt reperfusion group after 3 hr of reperfusion (260+/-120% vs 100+/-60%, staged vs abrupt at 3 hr, p < 0.03). The ratio of peak reactive hyperemic flow to resting flow in the staged reperfusion group was significantly greater than in the abrupt reperfusion group throughout the reperfusion phase (4.4+/-1.0 vs 2.6+/-0.6 at 3 hr, p < 0.001), and had returned to the preocclusion values after 3 hr of reperfusion. This preservation of the coronary flow reserve in the staged reperfusion group was observed in the epicardium (4.1+/-0.6 vs 2.8+/-0.7, staged vs abrupt at 3 hr, p < 0.01), but not in the endocardium or midmyocardium. Infarct size did not differ significantly between the two groups. Staged reperfusion in this study did not appear to attenuate the reduction of CBF, or to reduce infarct size, however preserved the coronary flow reserve, especially in the regions not severely damaged by ischemic injury.