The chordae tendineae are two tendons in the heart that contribute to the complex series of processes that happen with every cycle within the organ. These tendons are responsible for closing the valves that separate the ventricles from the atria to prevent the backflow of blood, ensuring that the blood is pushed through the pulmonary and aortic valves to circulate through the lungs and the body, respectively. Also known as the “heart strings,” these structures attach to the papillary muscles, which work to control valve movement, and to the tricuspid and mitral or bicuspid valves of the heart.
When the blood flows from the atria to the ventricles, a pressure differential is created that makes the blood want to push back into the atria. The pressure can be strong enough to force the flaps on the tricuspid and bicuspic valves to open, which is where the chordae tendineae come in. The heart strings tense up to keep the valves in position, leaving the blood with only one way to go: up into the aorta and pulmonary artery during ventricular systole, the period when the ventricles of the heart contract.
The processes involved in every heartbeat are carefully timed and entirely automatic, with the heart going through a cycle of contractions to push blood around the body, moving it through the lungs so that it will be oxygenated, and pushing the oxygenated blood into the aorta so that it can circulate through the body, bringing oxygen to the cells. The distinctive thump of the pulse is the result of ventricular systole, in which a contraction of the ventricles is used to build up pressure that forces the blood into the valves which exit the heart.
Sometimes, damage occurs to the valves as a result of disease processes in the heart. In this case, the heart valve may need to be repaired or replaced in a surgical procedure to address issues such as blood leakage which impair the function of the heart. The tendons themselves can also experience damage, usually in the form of rupture. Ruptures can be life threatening, and require immediate intervention.
In surgical procedures involving the valves or chordae tendineae, the patient must be put on cardiopulmonary bypass, with a heart-lung machine doing the work for the heart so that the surgeon can work on a still, mostly bloodless heart. The development of cardiopulmonary bypass allowed surgeons to perform procedures that would have been unthinkable before, when surgeons had to struggle to work with an actively beating heart.