The influence of sex-dependent vascular properties on aortic hemodynamics

Abstract

The motivation of this work stems from the lack of information regarding how differences in cardiovascular biomechanics between men and women underlie differences in abdominal aortic aneurysm disease. More specifically, the work seeks to ask two questions: 1. Are there differences in the wall shear stress profiles of the abdominal aortas of men and women that correlate to the increased risk of aortic aneurysms in men? 2. How do size and shape of the abdominal aorta, differences in peripheral blood flow as a result of pelvic organs, and differences in aortic tissue properties regulate these wall shear stress profiles in the sexes? To answer these questions, Magnetic Resonance Imaging of cardiovascular disease free volunteers was obtained. The above properties were quantified and compared for men and women. It was found that the abdominal aortas of men experience a higher degree of aortic blood flow oscillation which could elevate their risk for developing aortic aneurysms, an observation consistent with population prevalence of the disease. It was also discovered that differences in peripheral flow strongly contributed to the extent of oscillation and that an elevation in pelvic, and specifically uterine, blood flow protected women from these oscillations. The finding of this research suggests that there are specific innate properties of the vascular system that protect women from developing aortic aneurysms. It also highlights important parameters to consider when evaluating a woman’s risk of developing abdominal aortic aneurysmal disease. Finally this work has implications on how sex-based cardiovascular research should be approached in the future, with consideration for mechanical as well as biological factors.