Chordae tendineae
Chordae tendineae are strong, collagen-rich “tendinous cords” inside the ventricles that tether the atrioventricular valve leaflets (mitral and tricuspid) to papillary muscles. Their mechanical role is valve stabilization during ventricular contraction, preserving one-way blood flow through the heart.
Valve closure results primarily from a pressure gradient (ventricular pressure exceeding atrial pressure). Chordae tendineae and papillary muscles prevent leaflet inversion into the atria during systole.
Anatomical definition
Chordae tendineae are dense connective tissue cords composed primarily of collagen, organized to withstand repetitive tensile loading. Their naming reflects a tendon-like appearance, although they are specialized intracardiac structures rather than skeletal tendons.
Location in the heart
Chordae tendineae are located in the ventricles and attach to the leaflets of the atrioventricular valves.
- Mitral valve (left atrioventricular valve): chordae tendineae connect mitral leaflets to left ventricular papillary muscles.
- Tricuspid valve (right atrioventricular valve): chordae tendineae connect tricuspid leaflets to right ventricular papillary muscles.
Semilunar valves (aortic and pulmonary) do not use chordae tendineae; their leaflet stability relies on different geometry and pressure relationships.
Mechanical role during the cardiac cycle
Ventricular pressure rises sharply during systole. Atrioventricular valve leaflets close as ventricular pressure exceeds atrial pressure, and chordae tendineae transmit tension from papillary muscles to the valve leaflets. This tethering limits leaflet eversion into the atria, preserving valve coaptation and supporting unidirectional flow.
Papillary muscles contract during systole, not to pull the valves open, but to maintain appropriate chordal tension as ventricular geometry changes during contraction.
Comparison of left and right sides
| Feature | Mitral side (left) | Tricuspid side (right) |
|---|---|---|
| Valve type | Bicuspid (two main leaflets) | Tricuspid (three main leaflets) |
| Primary loading environment | Higher systolic pressures in the left ventricle | Lower systolic pressures in the right ventricle |
| Chordae–papillary attachment pattern | Chordae distribute force across two papillary muscle groups in typical anatomy | Chordae distribute force across multiple papillary muscle groups with broader leaflet partitioning |
| Functional outcome | Stabilized closure of the mitral valve to prevent left-sided regurgitation | Stabilized closure of the tricuspid valve to prevent right-sided regurgitation |
Clinical relevance
Damage to chordae tendineae compromises leaflet support and can produce acute or chronic valve insufficiency. Rupture of chordae tendineae is a classic mechanism for sudden worsening of mitral regurgitation when a leaflet loses tethering. Elongation or degeneration of chordae can also contribute to valve prolapse and murmurs.
Common misconceptions
- Valve opening mechanism: atrioventricular valves open primarily when atrial pressure exceeds ventricular pressure; chordae tendineae do not pull valves open.
- Role of papillary muscles: papillary muscles contract to maintain chordal tension and prevent leaflet prolapse during systole, not to close the valves.
- Presence in semilunar valves: aortic and pulmonary valves lack chordae tendineae; their function is achieved by leaflet shape and pressure-driven closure.