(See also Overview of Heart Valve Disorders.)
The tricuspid valve is in the opening between the right atrium and the right ventricle. The tricuspid valve opens to allow blood from the right atrium to fill the right ventricle and closes to prevent blood from flowing backwards into the right atrium as the right ventricle contracts to pump blood into the lungs. If a disorder causes the valve flaps to become thick and stiff, the valve opening is narrowed (stenosis). Often, the stiffened valve also fails to close completely and tricuspid regurgitation develops.
Over many years, the right atrium enlarges because blood flow through the narrowed valve opening is partially blocked, increasing the volume of blood in the atrium. In turn, this increased volume causes an increase in pressure in the veins bringing blood back to the heart from the body (except the lungs). However, the right ventricle shrinks, because the amount of blood entering it from the right atrium is reduced.
Nearly all cases are caused by rheumatic fever, which has become rare in North America and Western Europe. Rarely, the cause is a tumor in the right atrium, a connective tissue disorder, or, even more rarely, a birth defect of the tricuspid valve.
Symptoms are usually mild. They include palpitations (awareness of heartbeats), a fluttering discomfort in the neck, cold skin, and fatigue. Abdominal discomfort may result if the increased pressure in the veins causes the liver to enlarge.
Through a stethoscope, doctors may hear the characteristic murmur of tricuspid stenosis. A chest x-ray shows that the right atrium is enlarged.
People are encouraged to eat a low-salt diet and are given diuretics and drugs to block the effects of aldosterone (which help decrease pressure in the veins).
Surgical repair is usually avoided because tricuspid stenosis is rarely severe enough to require it and stenosis often recurs after the repair.