Mechanical properties of normotensive and hypertensive carotid and coronary arteries and their quantification

Abstract

Hypertension is a major risk factor for a variety of cardiovascular diseases like atherosclerosis, stroke, dissecting aortic aneurysms, etc. and is responsible for significant mortality and morbidity. Hypertension results in changes in the arterial wall structure, properties, biology, and function because of the existence of mechanical stress, i.e., increased blood pressure. Experimental and theoretical results are published with different animal models of hypertension, and time course of occurrence of these changes is neglected. Hence, a lack of complete understanding exists. In this paper, in vitro multiaxial (cyclic stretch and inflation) tests were performed on live carotid and coronary arteries from an aortic coarctation hypertension model of pigs, subjected to two, five, and nine weeks of hypertension. We found that increased blood pressure induced changes in the multiaxial stress-stretch response of the tested arteries. Changes were significant both in the axial and circumferential directions. Passive and active residual stress measurements also showed changes in opening angles, radius to thickness ratio, thickness, and area. Experiments revealed considerable activation of the hypertensive specimens as compared to that of normotensive specimens. Finally, multiaxial data was fitted with the Fung's constitutive equation to predict the arterial behavior.