Changes in the mechanical properties of human coronary arteries with age

Conclusions We were the first to experimentally find that the greatest changes in E₂, E_2(K) ^tan, _2(K), and W_(K) of the human cardial coronary arteries are observed in people who have reached the age of 40 years. To compare the experimental data, all the parameters of the mechanical properties of the coronary arteries were determined at one and the same stress level — 0.01 kgf/mm², which on an average corresponds to an increased intravascular pressure of within 200 to 240 mm Hg. Under elinical conditions, this pressure is considered critical for arterial vessels affected by atherosclerosis. The most marked shifts in the changes of the mechanical properties were found in the superior part of the left coronary artery. At the age of 40, a considerable decrease in the deformability of the arterial walls in the circular direction is observed, and the walls become more rigid. At the same time, the vessel wall becomes thicker, especially because of increase in its internal layer — the intima. All this facilitates the development of intravascular thrombosis in people suffering from coronary sclerosis and leads to the development of acute stenosis, frequently exceeding 75% of the clearance area of the vessel, or to a complete obstruction of the superior part of the left coronary artery. If the inferior part of this vessel still retains a fair deformability, it is possible to perform a reconstructive operation, by means of which normal blood circulation is restored from the initial part of the ascending aorta to the inferior section of the corresponding coronary artery. From the experimentally found characteristics of the mechanical properties of the inferior parts of coronary vessels, we can select the best autoplastic material — a vessel segment derived from the patient himself — with properties similar to those of the affected vessel, which ensures the successful performance of such an operation, namely, the reconstruction of the human coronary vessels.Lecture delivered at the Third All-Union Conference on Polymer Mechanics, Riga, November 10–12, 1976.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2,, pp. 277–282, March–April, 1977.