ABSTRACT

The right atrium (RA) receives blood low in oxygen from the vena cavae and delivers blood to the right ventricle (RV). The RV pumps blood into the pulmonary artery (PA). The left atrium (LA) receives oxygenated blood from the pulmonary veins and blood then flows into the left ventricle (LV). The atrioventricular valves are the tricuspid and mitral valves. The tricuspid valve allows one-way flow from the RA to the RV and the mitral valve from the LA to the LV. The semilunar valves are the pulmonic and aortic valves. The tricuspid and mitral valves open ventricular pressure drops to and then below the level of atrial pressure. Acquired or congenital valvular heart disease occurs when a valve orifice becomes narrowed or when a valve does not close completely. The murmur of aortic valvular stenosis cannot begin until flow starts through the narrowed aortic valve orifice.