Hypertension and aortic stenosis are the two most frequent cardiovascular diseases after coronary artery disease. Hypertension may be caused by an increase in systemic vascular resistance, a decrease in systemic arterial compliance, or both abnormalities. Among the patients with aortic stenosis, up to 40% have concomitant systolic hypertension. When hypertension coexists with aortic stenosis, the left ventricle faces a double pressure overload. However, the impact of hypertension on the hemodynamic, functional, and clinical outcomes in patients with aortic stenosis is unknown. Moreover, it is difficult to separate symptoms and complications caused by aortic stenosis from those caused by hypertension and thus to predict whether aortic valve replacement would be beneficial.

The main objective of the project is thus to study the hemodynamic interaction between aortic stenosis and hypertension and to determine their respective and combined effects on coronary circulation and left ventricular function. To reach these objectives, complementary numerical and in vitro studies are on-going.

The specific objective of these studies is to develop a mathematical model describing the interaction between the left ventricle, the valvular and vascular hemodynamics, and the left ventricular coronary circulation. We have combined a mathematical model of coronary circulation (proposed by Judd et al.) to the ventricular-valvular-vascular (V3) mathematical model recently developed and validated by our group. The results of the numerical simulations obtained with this new analytical model (V3C model) will be validated using our in-vitro mock flow model including a new mock flow model of the coronary circulation. The cardiac output, the degree of aortic stenosis severity, the systemic arterial compliance and the systemic vascular resistance will be varied independently. The results of these numerical and in-vitro studies will be used to examine the effects of aortic stenosis and hypertension on left ventricular load and the coronary circulation.

Relevance of the study: The better understanding of the inter-relation between valvular, vascular, coronary and ventricular hemodynamics shall provide important information for improving the diagnostic evaluation and therapeutic management of patients with aortic stenosis and hypertension. To the best of our knowledge, this will be the first study to examine the hemodynamic interaction between aortic stenosis and hypertension. This study could pave the way for future prospective studies in patients with aortic stenosis and hypertension.

This study is financially supported by a grant from the Canadian Institutes of Health Research.