chordae tendineae

Chordae tendineae are collagenous, cord-like structures arising from the tips of the papillary muscles within the ventricles and inserting onto the free edges and ventricular surfaces of the mitral (bicuspid) and tricuspid valve leaflets. Functionally, they work in tandem with papillary muscles: during ventricular systole, papillary muscles contract slightly before the rest of the ventricular myocardium, placing tension on the chordae tendineae to hold the valve leaflets in a closed position and prevent them from everting (prolapsing) into the atria under high ventricular pressure. This maintains competent valve closure and prevents regurgitant flow.

Clinically, chordae tendineae rupture is a critical topic. It can occur due to myxomatous degeneration (as in mitral valve prolapse), infective endocarditis, or ischemic damage/papillary muscle rupture following myocardial infarction (most commonly the posteromedial papillary muscle due to its single blood supply from the posterior descending artery). Rupture leads to acute, severe mitral regurgitation, presenting with sudden pulmonary edema, a new holosystolic murmur radiating to the axilla, and hemodynamic instability. This is a surgical emergency requiring valve repair or replacement.

Chronic conditions like rheumatic heart disease can cause chordae tendineae thickening, fusion, and shortening, contributing to valve stenosis or regurgitation. Understanding this structure is essential for interpreting murmurs, echocardiographic findings, and surgical valve anatomy on board exams.