Anatomic considerations for regional intimal changes in the coronary arteries (Dog)

Abstract Intimal proliferation in dog coronary arteries occurred in the vessel having the greatest range of motion. Within an involved segment of the artery, intimal proliferation could be related to the anatomy of the muscle bundles. Arterial muscle bundles originate from the adventitia, spiral around the artery and insert distally into the adventitia. The adventitia and the internal elastic lamina course along the long axis of the artery and are connected by elastin‐collagen fibers. Intimal thickening developed under the muscle insertion sites in regions where the adventitia was apparently placed under tension. In these regions, the net force of a muscle bundle contraction increases and shearing would occur between a muscle bundle at its insertion site and the remaining bundles gliding past it. This local shear force would then be transmitted to the internal elastic lamina through the elastin‐collagen fibers which connect it to the adventitia. Deformation and apparent injury of the internal elastica would follow and cause a fibrous tissue response. In the smaller arteries and arterioles, intimal proliferation occurred most prominently in the vessels supplying a mobile structure, i.e., anterior papillary muscle of the left ventricle.