Figure 1.

Schematic representation of a healthy and calcified aortic valve cusp. Cross sectional representation of a heart highlighting the aortic valve (box). (A) A healthy aortic valve cusp structure consists of three layers of extracellular matrix (ECM); the ventricularis (elastin fibers, black); the spongiosa (proteoglycans, blue); and the fibrosa (collagens, yellow). In addition to the matrix, the valve cusp is encapsulated by a single layer of valve endothelial cells (VECs), while valve interstitial cells (VICs) populate the core of the cusp. (B) A calcified valve cusp is thickened with abrogations in ECM organization including fragmented elastin fibers and increased collagen content. In addition, calcific nodules form on the fibrosa surface of the cusp (off-white).