The Influence of Cyclic Pressure and Angiotensin II on the Biomechanical Properties of Aortic Heart Valves

Hypertension, a risk factor for aortic valve stenosis, increases transvalvular load and can elicit extracellular matrix (ECM) remodeling. Elevated cyclic pressure and the vasoactive agent angiotensin II (Ang II) both promote collagen synthesis, an early hallmark of aortic sclerosis. It was hypothesized that increased collagen production induced by elevated pressure conditions or the presence of Ang II would affect the mechanical properties of leaflet tissue by decreasing extensibility. Porcine aortic valve leaflets were exposed to pressure conditions of increasing magnitude with and without Ang II. Biaxial mechanical testing was performed to determine peak stretch. Collagen content was determined using a quantitative dye-binding method. The results demonstrated Ang II and elevated pressure decrease the extensibility of leaflet tissue and increase the collagen content in the ECM. In conclusion, the results demonstrated that both elevated pressure and Ang II play a role in altering the biomechanical properties of aortic valve leaflets