Chordae tendineae of left atrioventricular valve

The chordae tendineae of the left atrioventricular valve (mitral valve) are fibrous structures that connect the papillary muscles of the left ventricle to the ventricular surfaces of the mitral valve leaflets. They are primarily composed of collagen bundles, with a core of densely packed, parallel collagen fibers providing tensile strength, surrounded by a layer of elastic fibers and covered by endocardium with squamous endothelial cells.This microarchitecture allows the chordae to withstand repetitive mechanical stress and maintain elasticity.

Chordae tendineae are classified by their leaflet attachment: primary (marginal) chordae insert at the free edge of the leaflets, secondary (strut) chordae attach to the ventricular surface (rough zone), and tertiary chordae (when present) connect to the base of the posterior leaflet or directly to the ventricular wall. The anterior and posterior papillary muscles each give rise to multiple chordae, which branch and fan out before inserting into the leaflets, forming a three-dimensional support network.

The chordae tendineae are avascular in most regions, but some, especially strut chordae, may contain small blood vessels and fibroblasts throughout their structure. Rarely, muscularized chordae may be observed, representing a developmental variant. The anatomical arrangement and microstructure of the chordae are essential for preventing leaflet prolapse and ensuring competent valve closure during systole.