The heart contains small, tough, fibrous cords known as chordae tendineae, sometimes referred to as “heart strings.” They are essential components that support the heart’s ability to pump blood effectively.
Anatomy and Location
Chordae tendineae are thin, string-like structures composed primarily of collagen. These cords have specific attachment points within the heart chambers. One end of each cord connects to the papillary muscles, which are muscular extensions protruding from the inner walls of the ventricles. The other end of the chordae tendineae attaches to the cusps, or leaflets, of the atrioventricular valves. This includes the tricuspid valve in the right ventricle and the mitral (bicuspid) valve in the left ventricle.
Essential Role in Heart Valve Function
The primary function of the chordae tendineae involves preventing the inversion or prolapse of the atrioventricular valve leaflets into the atria during ventricular contraction. As the ventricles contract to pump blood, pressure builds within these chambers. This pressure would force the valve leaflets to bulge backward into the atria, allowing blood to flow in the wrong direction. Working in conjunction with the papillary muscles, the chordae tendineae exert tension on the valve leaflets. The papillary muscles contract slightly before the main ventricular contraction and maintain this tension throughout. This action holds the valve leaflets firmly in place, preventing them from flipping back into the atria. This mechanism ensures that blood flows unidirectionally from the atria to the ventricles and then onward out of the heart. The chordae tendineae act like “guy wires” or “tethers,” supporting the valve flaps against the high pressure generated during ventricular systole. Their action is crucial in preventing backflow, or regurgitation, of blood into the atria.
Consequences of Dysfunction
When chordae tendineae are damaged, such as through rupture, elongation, or weakening, their ability to properly support the heart valve leaflets is compromised. This can lead to valve regurgitation, a condition where blood leaks backward through the affected valve instead of flowing forward. For example, if the chordae tendineae of the mitral valve are affected, blood can leak back into the left atrium during ventricular contraction.
Damage to these cords can arise from various causes, including degenerative conditions like myxomatous degeneration, which weakens valve tissue, or mitral valve prolapse. Infections, such as infective endocarditis, and physical trauma, like a chest injury, can also lead to rupture. Furthermore, a heart attack, or myocardial infarction, can sometimes result in damage to the papillary muscles, indirectly affecting the chordae tendineae. Rheumatic heart disease and the aging process also contribute to the weakening of these structures.
Symptoms of valve regurgitation can vary but often include shortness of breath, particularly during activity or when lying down, and a general feeling of fatigue. Individuals might also experience heart palpitations, an irregular heartbeat sensation, or swelling in the legs, ankles, and feet. A heart murmur may also be detected by a doctor. If left unaddressed, the heart must work harder to compensate for the backward blood flow, potentially leading to reduced blood flow to the body and, in severe cases, heart failure.