Figure 1.

Aortic valve cusp structure. A cross-sectional view of a normal TAV (center). Each valve cusp is comprised of a highly organized ECM (right) stratified into three layers: a collagen-dense fibrosa layer (aortic side), an elastin-rich ventricularis layer (ventricular side), and a spongiosa layer sandwiched in-between comprised mostly of proteoglycans. VICs are situated within the core of each cusp and maintain ECM synthesis and homeostasis. VECs form a protective monolayer encapsulating the entire cusp. A flattened perspective of a single aortic valve cusp (left) illustrates the locations of the tip, belly, and attachment regions. TAV, tricuspid aortic valve; ECM, extracellular matrix; VICs, valve interstitial cells; VECs, valve endothelial cells.