heart and blood vessel disorders
Overview of Heart Valve Disorders
Introduction
Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles). Each ventricle has a one-way "in" (inlet) valve and a one-way "out" (outlet) valve. Each valve consists of flaps (cusps or leaflets) that open and close like one-way swinging doors. In the right ventricle, the inlet valve is the tricuspid valve, which opens from the right atrium, and the outlet valve is the pulmonary (pulmonic) valve, which opens into the pulmonary artery. In the left ventricle, the inlet valve is the mitral valve, which opens from the left atrium, and the outlet valve is the aortic valve, which opens into the aorta. The mitral and tricuspid valves are held in place by tough, fibrous strings (chordae tendineae) that are connected to thin muscles (papillary muscles) that attach to the walls of the ventricles. This cross-sectional view of the heart shows the direction of normal blood flow. 