Changes in the mechanical properties, biochemical contents and wall structure of the human coronary arteries with age and sex.

An experimental study of the mechanical properties, biochemical composition and structure was carried out on the proximal and distal parts of the right and the anterior descending branch of left human coronary arteries. The vessels were removed during an autopsy of 121 males and 84 females being 1 day to 80 years old. The material was divided into six age groups. Branchless segments of vessels 15-20 mm long were cut from proximal and distal parts. The mechanical properties of the coronary arteries were determined by passing fluid at pressures ranging from 0 to 240 mmHg. It was found that the part of the wall of the coronary artery adjacent to the myocardium is thicker in all cases than the other part of the arterial wall. With increasing age the mean thickness of the wall of both coronary arteries increases but the wall-thickening process is non-uniform in nature in both the proximal and distal parts and in the individual layers. The changes in the stretch ratio and tangential modulus in circumferential direction with age and sex were investigated. The greatest changes in the wall thickness and in the mechanical parameters were found for the left coronary artery wall in men over 40 years of age and for the right coronary artery wall in women over 50 years of age. The results of biochemical and densitometric investigations were compared.

Biomechanical and structural assessment of transluminal angioplasty.

The increasing incidence of stroke is frequently maintained by the processes narrowing precerebral and cerebral arteries. That is why the surgical treatment of cerebrovascular disorders has increasingly included percutaneous transluminal angioplasty. However, the influence of transluminal angioplasty on the biomechanical properties of arterial wall have not been assessed so far. The cylindrical segments of left and right internal carotid artery, middle cerebral artery, anterior cerebral artery, vertebral artery, basilar artery and posterior cerebral artery were taken from 40 autopsy subjects aged from 20 to 75 who had no systemic lesions with the exception of atherosclerosis. The biomechanical examination and experimental transluminal angioplasty of the segments were carried out with special equipment developed for this purpose. The data were obtained using a TV camera assisted measurement and morphometric and histological methods. The examination of the biomechanical properties repeated after the experimental transluminal angioplasty shows the additional relative strain of the external diameter of vessel and the decrease of the arterial wall tangential elastic modulus in the circumferential direction. This suggests that if transluminal angioplasty results in sufficient structural damage of the arterial wall than there will be an improvement in the ability of the vessel diameter to increase under normal blood pressure conditions.