The tricuspid valve has three leaflets: the anterior, posterior and medial or septal leaflets. Together, these separate the right atrium from the right ventricle. During systole, or muscle contraction, the tricuspid valve closes, and during diastole, or heart relaxation, the tricuspid valve opens and lets blood fill the right ventricle. Tricuspid valve regurgitation happens when the tricuspid valve doesn’t close completely and blood leaks back from the right ventricle into the right atrium. Tricuspid valve stenosis happens if the tricuspid valve can’t open completely, making it difficult to fill the right ventricle.
Let’s start with tricuspid valve regurgitation. Often, regurgitation is due to pulmonary hypertension which causes an increase in right ventricular pressure. This pressure then dilates the tricuspid valve, allowing blood to go backward. Another well-known cause of regurgitation is rheumatic heart disease, an autoimmune reaction that involves the valve leaflets and causes inflammation. This chronic inflammation leads to leaflet fibrosis, which makes it so that they don’t form a nice seal and instead let blood leak through. Still another cause of tricuspid regurgitation is damage to the papillary muscles from a heart attack. If these papillary muscles die, they can’t anchor the chordae tendineae, which then allows the tricuspid valve to flop back and allows blood to flow backward from the right ventricle into the right atrium. There are also congenital causes for this condition, like Ebstein’s anomaly, which is when a person is born with leaflets that are located too low, i.e., in the ventricle rather than between the atria and the ventricle, and this makes it hard for the leaflets to form a nice seal.
