The heart is a beating muscle that pumps blood throughout the body. Inside the heart, four valves open and shut in a precise sequence that keeps the blood moving in the appropriate direction. A malformed or damaged valve may not close properly, allowing blood to leak backwards. This condition is called valvular regurgitation, or valvular insufficiency.
In a healthy heart, two valves control the flow of blood from the upper chambers, or atria, to the lower chambers, or ventricles. Two other valves control blood flow from the ventricles to the lungs and body.
Oxygen-rich blood moves from the left atrium to the left ventricle through the mitral valve. The ventricle pumps the blood through the aortic valve to be distributed throughout the body. Oxygen-poor blood moves from the right atrium to the right ventricle through the tricuspid valve, and is pumped through the pulmonic valve on its way to the lungs to pick up oxygen.
The two atrioventricular valves, the mitral valve, and the tricuspid valve, are connected to the ventricles by thin, fibrous strands of tissue called chordae tendineae. The chordae tendineae, along with papillary muscle hold the flaps, or cusps, of each valve in place. When the ventricles contract, pressure gradients across the valves pull the cusps of the mitral and tricuspid valves shut.
If there is not enough tension on the chordae tendineae, the cusps may not close properly and blood may leak backwards, or regurgitate. In this example, the cusps of the mitral valve are prolapsing, or failing to close properly. Blood is leaking back into the left atrium from the ventricle.
The valves of the lower two chambers, the pulmonic and aortic valves, open and close due to the changes in pressure from the contractions of the atria and ventricles. These valves are also susceptible to disease or damage, causing regurgitation as a result of a leaky valve.
Because blood is leaking in side the heart, less oxygen-rich blood is circulating throughout the body, causing the heart to work harder. If not treated, valvular regurgitation can lead to heart damage or further valve damage.