Chordae TendineaeEdit
Chordae tendineae are slender, cord-like structures inside the heart that connect the leaflets of the atrioventricular valves to the papillary muscles within the ventricles. Their primary role is to prevent the valve leaflets from inverting or prolapsing during the high-pressure phase of systole, thereby ensuring one-way blood flow from the atria to the ventricles and onward to the great vessels. These cords are a key component of the subvalvular apparatus that stabilizes the mitral valve mitral valve and the tricuspid valve tricuspid valve throughout the cardiac cycle. The chordae attach to the leaflets of the valves and to the papillary muscles in the left and right ventricles, forming a dynamic tethering system that helps coordinate valve motion with ventricular contraction. See also the anatomy of the papillary muscles and the chambers they inhabit, the left ventricle and the right ventricle.
Structure and Function
Architecture
Chordae tendineae consist of dense, collagen-rich connective tissue organized into several subtypes. They are distributed across the leaflets of the atrioventricular valves, with the majority attaching near the edges and the basal portions of the leaflets and extending to the corresponding papillary muscles in the ventricle. The leaflets themselves belong to the class of valves of the heart, and their coordinated motion depends on the integrity of these cords and the subvalvular apparatus.
- Edge (marginal) chordae: attach to the free edges of the leaflets and are often numerous.
- Strut and basal chordae: provide additional tethering and structural support near the base of the leaflets.
- Parachordae: slender filaments that extend from the ventricular wall or papillary muscles toward the leaflets and help transmit tension.
The left heart, housing the mitral valve, generally experiences greater systolic pressures than the right heart, making the left-sided chordae particularly important for maintaining proper leaflet coaptation. The chordae communicate with the surrounding tissues of the endocardium and the subvalvular apparatus to distribute tension during systole.
Attachment and mechanics
During systole, when the ventricles contract and pressure rises, the chordae tendineae transmit tensile forces from the leaflets to the papillary muscles. This action keeps the leaflets from bulging back into the left atrium or right atrium and assists in forming a tight seal with the opposing atrioventricular valve orifice. The mechanics of this system are a balance: sufficient tethering to prevent prolapse, but not so rigid as to impede normal leaflet excursion during diastole.
Development and Variation
Chordae tendineae develop as part of the heart’s subvalvular apparatus during embryologic formation of the valves of the heart. They are composed predominantly of collagen and extracellular matrix, with their density and organization adapting to the functional demands of the ventricles they support. While there is variation among individuals, the general pattern includes a dense network of cords connecting each valve leaflet to its corresponding papillary muscles.
Clinical Significance
Common conditions
Damage or disease affecting the chordae tendineae can lead to regurgitant heart lesions, the most familiar being mitral regurgitation when chordae rupture or elongate excessively. Causes include: - Rupture of chordae tendineae due to acute myocardial infarction involving the papillary muscles, leading to sudden severe regurgitation. - Myxomatous degeneration of the mitral valve leaflets and chordae, a process associated with mitral valve prolapse. - Infective endocarditis, in which infectious destruction can compromise chordal integrity. - Chronic ischemia or dilated cardiomyopathy that alters the geometry of the subvalvular apparatus.
A ruptured chord tends to produce acute, well-recognized symptoms and hemodynamic consequences, often requiring urgent assessment and management. Lesions of the chordae may be part of broader valvular disease, which is categorized under the larger umbrella of valvular heart disease.
Diagnosis and imaging
Clinical evaluation is complemented by imaging. Echocardiography, especially transesophageal echocardiography, is the principal tool for visualizing chordae, leaflet motion, and the overall architecture of the subvalvular apparatus. Cardiac MRI can provide alternative or supplementary details in certain cases, but echocardiography remains the standard first-line modality for assessing chordal integrity and associated valve function.
Surgical considerations
When surgical repair is indicated, preserving or reconstructing the subvalvular apparatus is often a priority because it helps maintain left ventricular function and geometry. Techniques include: - Chordal replacement or transfer with artificial materials to restore leaflet tethering. - Chordal-sparing approaches during mitral valve repair to maintain apposition and ventricular performance. - Annuloplasty and other restorative procedures that complement chordal repair.
In mitral valve disease, surgeons aim to restore competent leaflet motion while preserving as much of the native subvalvular framework as possible. Discussions about repair versus replacement frequently emphasize the functional advantages of maintaining chordal integrity.
Imaging and research
Advances in imaging have enhanced understanding of chordal morphology, variants, and pathology. Researchers and clinicians study chordal mechanics, their role in ventricular-arterial coupling, and how surgical techniques influence long-term outcomes. See also echocardiography for diagnostic methods and cardiac surgery for therapeutic strategies.