Hemodynamic mechanisms of bicuspid aortic valve calcification and aortopathy

Abstract

The bicuspid aortic valve (BAV) is the most common congenital cardiac anomaly and is present in 2-3 % of the general population. While the BAV anatomy may not intrinsically hamper valvular function, it is associated with a spectrum of secondary valvulopathy and aortopathy such as calcific aortic valve disease and aortic dilation. The current clinical management of BAV disease presents significant challenges related to the nontrivial identification of BAV patients, the difficult detection of the onset of aortic and valvular complications and the time-sensitivity of surgical intervention. The design of effective clinical guidelines and surgical procedures requires the elucidation of the etiology of BAV complications, which remains controversial. While BAV calcification and aortopathy have been linked to the same congenital defect as that responsible for the BAV morphogenesis, the abnormal BAV hemodynamics has emerged as a potential alternate or coincident etiology. Given the particular sensitivity of valvular and vascular tissues to their surrounding mechanical environments, the fluid shear stress abnormalities produced by a BAV may trigger pathological pathways that ultimately lead to leaflet calcification and aortic wall degeneration. Therefore, the assessment of the hemodynamic theory of BAV valvulopathy and aortopathy requires the investigation of the potential cause-and-effect relationships between the local hemodynamics of the leaflets and the aortic wall and their local biology. This chapter describes the most recent experimental, computational and ex vivo approaches that have been implemented to characterize the native BAV hemodynamics and elucidate its role in BAV disease.