Calcific aortic valve disease (CAVD) is a cell-mediated pathology without effective pharmacotherapy whose early pathogenesis is drastically understudied. C-type natriuretic peptide (CNP) is expressed 3x more on the disease-protected ventricular side than the disease-prone aortic side of the valve, and inhibits valvular interstitial cell myofibrogenesis and osteogenesis in vitro. Importantly, CNPâ s functional significance to CAVD in vivo has not been studied. In this thesis, a mildly atherogenic dietary mouse model of CAVD was characterized. Diet-induced proteoglycan synthesis identified in these mouse valves was versican-rich, occurred along with increased SOX9 expression, and developed before myofibrogenesis, calcification, or deficits in valvular function. Subsequently, mice with a loss-of-function mutation of the CNP receptor Npr2 were employed to test whether CNP/NPR2 were protective against CAVD in vivo. Npr2+/- mice developed cardiac dysfunction, hypertrophy, and fibrosis. Npr2 deficiency produced impaired valve function, which was exacerbated by long-term hypercholesterolemia. A portion of Npr2+/- mice had bicuspid aortic valves (BAVs, ~10%) with the most severe deficits in valvular function, and worst cusp thickening, fibrosis, and calcification. Lastly, NPR2-deficient mice developed ascending aortic dilatations characterized by elastin fragmentation and loss of medial collagen and smooth muscle cells;​ dilatation was accelerated in those mutants with BAVs. Abnormal hemodynamics likely contribute to aggravated CAVD and aortic dilatation in BAVs. However, there is a lack of tools to quantify complex hemodynamics in small animals where genetic/metabolic contributions to disease can be controlled. Echocardiographic particle image velocimetry (echoPIV) without exogenous contrast particles was employed with high-framerate ECG-gated Kilohertz Visualization (EKV) to track erythrocyte movement in the mouse ventricle and aortic root. EKV+echoPIV identified strong ventricular vortices during diastolic filling that transitioned to high-velocity systolic outflow. In the aortic root, that systolic aortic jet with recirculatory flow in the sinuses was apparent;​ oscillatory flow occurred once valve leaflets apposed. In summary, this thesis sheds light on the early pathogenesis of CAVD, identifies a novel therapeutic signaling axis in vivo, and presents a novel imaging technique for quantifying hemodynamics in small animal models of cardiovascular disease.