Regional myocardial blood flow in experimental myocardial infarction after pretreatment with aspirin.

The effects of aspirin on myocardial blood flow in an area of ischemia were studied in 12 baboons. In each, a diagonal branch of the left anterior descending coronary artery was ligated. Six of the baboons received aspirin (2 X 600 mg orally, 12 hours and 1 hour before ligation); the other six did not receive aspirin and served as a control group. The extent of myocardial ischemia was delineated with an electrode wire grid on the surface of the anterior left ventricular wall. The maximal area circumscribed by electrodes with 2 mV or more ST segment elevation was compared with the area of reduced myocardial blood flow. Myocardial blood flow was measured with the radioactive microspheres method using strontium-85-labeled carbonized spheres. Two areas of reduced myocardial blood flow were noted, one with severely reduced flow in the center of the myocardial infarct (0 to 49% of noninfarcted myocardium) and another with mild to moderately reduced myocardial blood flow at the border of the myocardial infarct (50 to 90% of noninfarcted myocardium). Myocardial blood flow in the border area (margins of ST elevation area) for the total wall was 85 +/- 8% of normal in the aspirin-treated animals and 40 +/- 4% in the control group (p less than 0.01); for the epicardium it was 67 +/- 10% of normal in noninfarcted myocardium after aspirin and 37 +/- 5% for the control group (p less than 0.05); and for the endocardium it was 78 +/- 8% of normal in noninfarcted myocardium after aspirin and 39 +/- 6% in the control group (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)