Residual strain in human atherosclerotic coronary arteries and age related geometrical changes.

The opening angles of 16 rings excised from human coronary arteries with different degrees of atherosclerosis were determined 10 hours after death. Atherosclerosis, as a chronic inflammatory response of arterial endothelium and intima, is defined by three degrees of its development. The opening angle decreases more or less linearly with the distance from the right coronary artery orifice. This is in accordance with the functional requirements posed on blood transport into the coronary arteries. A decrease of the opening angle with age is affected by hardening of the arterial wall, among other factors. This is in accordance with a stochastic model of age related changes in the initial modulus of elasticity of the coronary artery. A part of the free energy of smooth muscle cells, fibroblasts, collagen and elastic fibres is used not for creating residual strain but for remodeling the arterial wall structure. The opening angle is also considerably affected by the degree of atheroclerosis. The dependence on age of the external diameter and the thickness of the intact left and right coronary arteries in the vicinity of the aortic sinus was also analyzed in two female and two male subjects. To ensure the objectivity of the results it is necessary to carry out additional experiments and studies in vivo.