What are the chordae tendineae?
The chordae tendin(e)ae, heart strings, or tendinous chords are tough bands of fibrous tissue that connect the leaflets of the bicuspid and tricuspid valves to the papillary muscles in the walls of the two bottom heart chambers, the ventricles.
The cord-like tendons regulate the opening and closing of the leaflets of the heart’s valves between the upper and lower chambers during the cardiac cycle. There are three main types of chordae: primary (marginal) chordae, secondary (basal) chordae, and tertiary chordae.
What do the chordae tendinae look like?
The tendinous chordae are made up of collagen (a protein in human connective tissues), elastin, and endothelium. They look like a series of sinewy cords or strings of varying thickness and length.
Playing a vital role in valve function, the strings connect to the five leaflets of the two atrioventricular valves on one end and attach to the heart’s five papillary muscles on the other (two in the left ventricle‘s anterior and posterior, and three in the septal, posterior, and anterior right ventricle).
What is the function of the chordae tendineae? How do they function?
When the heart beats during the cardiac cycle, the atria and ventricles contract and the open bicuspid and tricuspid valves are pushed closed due to blood pressure in the chambers.
The relaxed chordae tendineae tense up to hold the cusps (leaflets) of the atrioventricular valves in place when they close. This prevents prolapsing of the valve leaflets and keeps blood from regurgitating into the upper atrial chambers (the left atrium and right atrium).
What can go wrong with the chordae tendinae?
Like the papillary muscles, the chordae can rupture. They can also stretch or tear, causing valve dysfunction. Either situation can be life threatening and requires urgent surgical intervention.
Damage can occur as a result of a heart attack, physical trauma, or serious infections like infective endocarditis. Heart valve conditions like subvalvular aortic stenosis can also affect the chordae.