Infarct distribution in subhuman primates after acute coronary occlusion

The extent of epicardial, endocardial and septal infarct was determined in 24 monkeys and five baboons 1 week after acute left anterior descending or diagonal branch coronary artery ligation. All 24 Macaca cynmologous monkeys had non-dominant left anterior descending coronary arteries. A snare ligature was placed just distal to the first diagonal branch for varying time periods (1, 2, 4, and 6 h followed by reperfusion or left in place permanently). In five baboons a chronic ligature was placed around a diagonal branch. All animals lived and were killed a week later. Histological mapping and planimetry of serial cross-sections were employed to quantify the extent and distribution of the infarct. All infarcts were transmural. The extent of epicardial infarct was significantly greater than the extent of endocardial infarct for the 2 h ligations (3.5 ± 0.87% of the left ventricle versus 2.4 ± 0.58% of the left ventricle, P <0.05), the chronic left anterior descending coronary artery ligations (5.4 ± 1.06% of the left ventricle versus 4.5 ± 0.92% of the left ventricle, P <0.05 and for the chronic diagonal branch ligations (4.06 ± 0.66% of the right ventricle + left ventricle versus 2.64 ± 0.51 % of the right ventricle + left ventricle, P <0.02). It is evident, however, that the magnitude of this epicardial preponderance was not great and that, in general, the infarcts were transmural and rectangular in configuration.