Age and atherosclerosis--related changes occurring in the "intercalated vascular segments" of human coronary arteries

The term "intercalated vascular segment" is used by the authors to designate a structural accomodation to the existence of diffuse thickened intimas, occurring as local vascular connections between the lumen of the main coronary arteries and the branch mouths of the daughter vessels. They exhibit the light microscopic feature of cylindrical conduits including only an endothelial sheet encased by the intimal connective tissue. The most important change related to aging and atherosclerotic involvement seems to be the conversion of some intercalated vascular segments in rigid, undistensible and narrowed conduits; this might produce local changes similar to those of a fixed stenosis. In the material examined the presence of narrowed conduits was sometimes associated with the existence of small areas of necrosis in the myocardium supplied by the vessel corresponding to the respective intercalated vascular segment.