The chordae tendineae are flexible strands in the heart that regulate the opening and closing of the flaps of the valves between the heart's upper and lower chambers. The chordae tendineae ensure these flaps are pulled shut whenever the ventricles, or the lower chambers of the heart, contract.
The effective functioning of the heart depends on the chordae tendineae opening and closing the flaps of the mitral and tricuspid valve at regular intervals. This ensures constant blood flow between the chambers of the heart and between the heart and the rest of the body. The left ventricle receives oxygen-rich blood from the left atrium through the mitral valve and sends it out into the body. Conversely, the right ventricle receives deoxygenated blood from the right atrium through the tricuspid valve and sends it to the lungs for oxygenation. Blood leaves the heart via the pulmonic and aortic valves, which do not have chordae tendineae.
The functioning of chordae tendineae may be adversely affected if they are under insufficient tension, in which case blood can leak back from the ventricles into the atria instead of leaving the heart and flowing to the lungs or into the body. This happens because lack of tension in the chordae tendineae leaves the flaps of the valves between the ventricles and atria unable to close properly. If left untreated, this can lead to valvular regurgitation, a condition which may cause heart damage.