Pressure pulse wave velocity and axial prestretch in Arteries

Abstract

The velocity of the propagation of a pressure pulse wave is considered to be a useful marker of the state of health of the cardiovascular system. Many clinical measurements, laboratory experiments and computational simulations have proved that the pressure pulse velocity correlates with age-related changes in the mechanical properties of arteries. Age-related stiffening of arteries, referred to as arteriosclerosis, leads to the increase in the pressure pulse velocity. However, the stress and strain state of an artery is not given solely by its loading and mechanical properties. Arteries are residually stressed that can be seen when cylindrical segment of an artery is excised from the body. The segment retracts because the axial prestretch is released. This prestretch declines with age, as a consequence of the damage accumulated to elastic lamellae during aging. Previous studies have paid little attention to the effect of axial prestretch on the velocity of the pressure pulse wave. The study presented here is based on a combination of a linearized 1D model of the fluid dynamics and the nonlinear anisotropic response of the human abdominal aorta. The model predicts that the application of axial prestretch can significantly change the velocity of the pressure pulse. To be more specific, preliminary results suggest that within the range of physiological pressures, the model that considers initial axial stretch of the aorta predicts lower pressure pulse velocity in comparison with the model that neglects axial prestrain of the tube.