The purpose of this study was to determine the effect of reperfusion about infarct size and infarct expansion by different duration of ischemic time. Temporary coronary ligation was performed in rats for 30min, 60min, 90min and 120min, followed by reflow. Rats with permanent ligation were used for comparison. After 7 days, transverse histologic heart sections were prepared for structual analysis. The results were as follows ; 1) Reperfusion after 30 min ischemic time 1.Infarct size of reperfusion (method 1 ; 16.5+/-8.3%, method 2 ; 20.9+/-8.0%) was smaller than that of permanent ligation (method 1 ; 29.8+/-8.9%, method 2 ; 33.5+/-12.1%)(p<0.01, p<0.05). 2. Expansion index of reperfusion (46.9+/-19.6) was smaller than that of permanent ligation (88.0+/-34.9)(p<0.01). 3. The infarct thickness of reperfusion (1.59+/-0.40mm) was larger than that of permanent ligation (1.10+/-0.21mm)(p<0.01). 4.The viable left ventricular tissue area of reperfusion (28.8+/-2.90mm2) was larger than that of permanent ligation (24.2+/-3.10mm2)(p<0.01). 2) Reperfusion after 60 min ischemic time 1. There was no difference in infarct size between reperfusion and permanent ligation. 2. Expansion ratio (27.2+/-5.9%) and expansion index (51.8+/-24.6) of reperfusion were smaller than those of peremanent ligation (35.7+/-7.4%, 88.0+/-34.9)(p<0.05, P<0.05). 3. The infarct thickness of reperfusion (1.48+/-0.32mm) was larger than that of permanent ligation (1.10+/-0.21mm)(p<0.01). 3) Reperfusion after 90~120 min ischemic time reduced neither infarct size nor infarct expansion. The results of this study in the rat preparation suggest a beneficial effect of reperfusion even in late on infarct expansion independent of myocardial salvage.
Animals ; Heart ; Ligation ; Myocardial Infarction* ; Rats* ; Reperfusion*