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Measurements of the diameter of the coronary artery (left main, left anterior descending branch, left circumflex branch, right) and the length of the coronary artery (left main, left anterior descending) were performed in 77 cases obtained from corpses with normal and mild atherosclerosis of coronary artery. Fifty-six males and 21 females were studied whose ages ranged from 15 -78 years old. The diameter of the coronary artery exponentially increased in accordance with the increase of age (left main coronary artery: lumen diameter=1.847+0.216 X age, R2=0.632, p<0.01; left anterior descending branch: lumen diameter=1.513 +0.241 X age, R2=0.539, p<0.01; right coronary artery:lumen diameter=1.830 +0.193 X age, R2=0.513, p<0.01; left circumflex branch: lumen diame-ter= 1.470+0.159 X age, R2=0.502, p<0.01). The lumen diameter of the left main coronary artery, the length of the left anterior descending branch and the thickness of the left anterior descending branch exponentially increased in accordance with the increase of the heart weight(left main coronary artery: lumen diameter=1.721+0.031 X heart weight, R2=0.338, p<0.01; left anterior descending branch: length=7.114+0.103 X heart weight, R2=0.313, p<0.01; left anterior descending branch: wall thickness=0.226+0.009 X heart weight, R2=0.256, p<0.01). But no significant difference was observed between the diameter, length of the coronary artery and various body indices, and heart weight. Microscopic and immunohistochemical studies on coronary arteries of 77 cases showed high frequency of diffuse intimal thickening with many smooth muscle cells and scanty macrophages and fragmentation of internal elastic lamina in arteries without atherosclerosis. These results indicate that the lumen diameter of coronary artery is closely correlated with age but not with various body indices and heart weight, and the length of the anterior descending branch is closely correlated with heart weight but not with age and various body indices. The results of the microscopic and immunohistochemical studies indicate that the early event of the atherosclerosis of the coronary artery is intimal thickening and fragmentation of internal elastic lamina.
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