Impaired human coronary artery distensibility by atherosclerotic lesions: a mechanical and histological investigation

The objective of this study was to evaluate the relationship between human coronary artery distensibility and vessel wall morphology assessed by histomorphometry. Coronary artery pressure-cross-sectional area relations and distensibility were studied in excised autopsy hearts by means of a balloon-based impedance planimetric technique 2 cm from the aortic orifice of the arteries. Later the hearts were perfusion fixed at 100 mm Hg and cross-sectioned 17, 20 and 23 mm distal to the aortic orifice. The areas of lumen, intima and media were measured. Nineteen left anterior descending coronary arteries (LAD) and 15 right coronary arteries (RCA) from 25 hearts (12 women and 13 men) were investigated. The age of the subjects was 48-97 years (mean 73.8 years). Non-linear relations were found between balloon pressure and coronary cross-sectional area (according with the function y = a + bx0.5) and between balloon pressure and coronary distensibility, but there were no differences in these relations between the LAD and RCA. Subjects' age was positively correlated with wall thickness (r = 0.44, P < 0.05), intima area (r = 0.46, P < 0.01) and media area (r = 0.44, P < 0.05) of the coronary arteries. Additionally, the distensibility at low pressures was inversely correlated with arterial wall thickness (r = -0.37, P < 0.05). When focusing only on arteries with concentric atherosclerotic lesions, distensibility at low pressures was inversely correlated with arterial wall thickness (r = -0.57, P = 0.01) and intima area (r = -0.53, P < 0.05). Arteries with concentric lesions were less distensible at low pressures compared with arteries having eccentric lesions (5.4 +/- 0.8.10(-2) vs. 3.6 +/- 0.7.10(-2) kPa-1, P < 0.05) but this difference was absent at higher pressures. No difference in coronary artery distensibility was found between men and women. Age and distensibility were not correlated. These findings may have in vivo implications for complications to angioplasty procedures such as recoil and restenosis.