Localization of atherosclerotic lesions in the bifurcation of the main left coronary artery.

The detailed distribution of atherosclerotic lesions in the branching region of the left main coronary artery in man was studied. Tissue cubes of the hearts, containing the left coronary arteries, were removed, and 1.5-mm-thick parallel and consecutive slices were cut perpendicular to the main coronary artery. Histological sections of the slices were stained and photographed. Drawings of the cross-sections of the arteries, including information about thickness of the intima and borders of the atherosclerotic lesions, were fed into a computer, scaled and analyzed. Casts were made of the left main coronary bifurcation from additional hearts. The curvature of the arteries and the angles of the bifurcation were measured. Atherosclerotic lesions have a distinct pattern with a high frequency on the outer walls of the bifurcation and at the inner curvature downstream from the bifurcation. The extent of intimal thickening and the occurrence of atherosclerotic lesions were mostly in agreement.