Localization of atherosclerotic lesions in the human basilar artery.

The topography of atherosclerotic lesions in the human basilar arteries has been studied quantitatively by digitizing images of the excised vessels and producing contour probability maps. Fifteen basilar arteries were obtained at autopsy (age--61 +/- 2; males--6, females--9; black--6, white--9), fixed in formalin, opened along the ventral aspect and stained grossly with Sudan IV to delineate fat-containing lesions. Photographs of the flattened arteries were analyzed and the presence or absence of sudanophilic lesions was determined at approximately 1000 identical sites on all vessels. The probability of finding a lesion at each site was determined and a contour probability map was constructed. Fifty-two percent of the area of the mean contour map was involved with lesions. The extent of the sudanophilic lesions decreased as one proceeded distally from the origin of the basilar artery at the confluence of the vertebral branches (i.e. proximal 1/3--56%; middle 1/3--49%; distal 1/3--43%; P less than 0.04). Significantly more sudanophilic material was observed on the ventral (outer curvature) as opposed to the dorsal (inner curvature) surfaces (55%, 43% respectively; P less than 0.03). These data suggest that hemodynamic forces associated with confluent flow and curvature may be important in the localization of sudanophilic lesions in the proximal and ventral aspects of the human basilar artery.