The heart functions as a muscular pump, propelling blood throughout the body to deliver oxygen and nutrients. This intricate organ contains various internal components that coordinate to ensure efficient blood circulation. Among these structures are the chordae tendineae, often referred to as the “heart strings,” which play a specific, yet frequently overlooked, role in maintaining the heart’s one-way blood flow. Understanding these fibrous cords reveals an important aspect of cardiac mechanics.
Understanding Chordae Tendineae: Location and Structure
The chordae tendineae are cord-like structures made of fibrous connective tissue, primarily collagen, with some elastin providing elasticity. They are found within the heart’s ventricles, the lower pumping chambers. These inelastic cords connect the cusps, or leaflets, of the atrioventricular (AV) valves—the tricuspid valve on the right side and the mitral (bicuspid) valve on the left side—to small, muscular projections called papillary muscles, located on the inner walls of the ventricles. Multiple chordae tendineae attach to each leaflet, resembling the strings that support a parachute.
The chordae tendineae are classified based on their insertion points on the valve leaflets. This arrangement ensures comprehensive support for the valve leaflets.
The Role of Chordae Tendineae in Heart Function
The primary function of the chordae tendineae is to prevent the heart’s atrioventricular valves from prolapsing, or inverting, back into the atria during ventricular contraction. When the ventricles fill with blood, the AV valves open, and the chordae tendineae are relaxed. As the ventricles contract, the pressure within these chambers significantly increases, pushing blood towards the arteries.
Simultaneously, the papillary muscles contract, pulling on the chordae tendineae. This tension keeps the valve leaflets firmly closed and prevents them from bulging backward into the atria, which are the upper receiving chambers of the heart. This coordinated action maintains the integrity of the valves, ensuring that blood flows in a single direction: from the ventricles into the main arteries (pulmonary artery and aorta) and not back into the atria.
The chordae tendineae, in conjunction with the papillary muscles, prevent regurgitation, the backward flow of blood. For example, the mitral valve closes to prevent oxygen-rich blood from flowing back into the left atrium as the left ventricle pumps blood to the body. Without these “heart strings,” high pressure during ventricular contraction would compromise the heart’s pumping efficiency.
Consequences of Chordae Tendineae Dysfunction
When the chordae tendineae are damaged or malfunction, the heart’s ability to pump blood efficiently can be compromised. Common issues include rupture, where one or more cords break, or elongation, where they become stretched. Thickening or abnormal structures of the chordae tendineae can also impair their function. These problems can arise from various conditions, including myxomatous degeneration, infective endocarditis, trauma, or connective tissue disorders.
A ruptured chordae tendineae can lead to sudden, severe mitral regurgitation, where blood leaks backward into the atria during ventricular contraction. This can result in symptoms such as shortness of breath, chest pain, and signs of hemodynamic instability, potentially leading to heart failure.
Elongation of the chordae tendineae can also contribute to valve leakage, as the stretched cords may not adequately support the valve leaflets, causing them to prolapse. Significant changes can lead to chronic mitral regurgitation. Such valvular issues can cause the heart to work harder, potentially leading to heart murmurs, an enlarged heart, or, in severe cases, heart failure over time.