chordae tendineae

The chordae tendineae are the heart's tiny guy-ropes — sometimes nicknamed the heartstrings. Like the cords that stop an umbrella from flipping inside out in the wind, they hold the valve flaps in place when the pressure inside the ventricle suddenly spikes.

These thin, fibrous cords connect the leaflets of the two atrioventricular valves — the mitral valve and the tricuspid valve — to the papillary muscles on the inner wall of the ventricles. They do not pull the valves open or shut; rather, they restrain the leaflets so they cannot billow backward into the atrium during contraction.

If a cord stretches or ruptures — for example from degeneration, infection, or a heart attack damaging a papillary muscle — the affected leaflet flails and the valve suddenly leaks. This is one mechanism of acute mitral regurgitation, which can cause rapid and dangerous shortness of breath.