Location and Morphology of Hypertensive Lesions in Coronary Arteries of Dogs

Summary

Hypertension was produced in coronary arteries of 54 foxhounds by afterload stress with supravalvular aortic stenosis. Functional hemodynamic studies were carried out after 3 months and one year of hypertension. Other dogs were perfusion fixed after 3 months and one year of hypertension for morphologic analysis of coronary arteries with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and light microscopy (LM). SEM results of coronary arteries subjected to hypertension show little change from normal coronary arteries after three months. Only isolated cases of bright spindle-shaped cells which appear to be sloughing from the surface were seen directly proximal to ostia of coronary arteries. TEM showed no ultrastructural changes in this banding group. SEM observations of coronary arteries after one year of hypertension revealed areas of endothelial denudation oriented parallel to the longitudinal axis of the artery, a few cell diameters wide and 200–300 μ in length. These lesions were often seen to form narrow channels between two or more branching points, either in a continuous or in series fashion. Denudations were restricted to arteries greater than 1 mm in diameter. Platelets, lymphocytes, granulocytes, and monocytes adhered to the subendothelial surface. Also in proximity to branching points were heterogeneous populations of cells adherent to intact endothelium. TEM and LM of this group showed breaks and duplication in the intima. Focal areas of inflammatory cells and plasma insudation in the intima were noted in areas exhibiting endothelial surface adherence.