Tricuspid regurgitation is a disorder involving backward flow of blood across the tricuspid valve which separates the right ventricle (lower heart chamber) from the right atrium (upper heart chamber).

This occurs during contraction of the right ventricle and is caused by damage to the tricuspid heart valve or enlargement of the right ventricle.

The most common cause of tricuspid regurgitation is not damage to the valve itself, but enlargement of the right ventricle, which may be a complication of any disorder that causes failure of the right ventricle.

Other diseases can directly affect the tricuspid valve. The most common of these is rheumatic fever, which is a complication of untreated strep throat infections. The valve fails to close properly, and blood can flow back to the right atrium from the right ventricle, and from there back into the veins. This reduces the flow of blood forward into the lungs. The condition affects about 4 out of 100,000 people.

Another important risk factor for tricuspid regurgitation is use of the diet medications called "Fen-Phen" (phentermine and fenfluramine) or dexfenfluramine.

Tricuspid regurgitation may be found in the setting of congenital heart disease (Ebstein anomaly). Rarely tricuspid regurgitation can be caused by an unusual tumor called carcinoid. This tumor secretes a hormone which damages the valve. Other infrequent causes of tricuspid regurgitation include rheumatoid arthritis, radiation therapy, Marfan syndrome, and injury.

Ttricuspid regurgitation may not produce any symptoms if the patient does not havepulmonary hypertension. If pulmonary hypertension and moderate-to-severe tricuspid regurgitation exist together, the following symptoms may result:

• Active pulsing in the neck veins
• Swelling of the abdomen
• Swelling of the feet and ankles
• Fatigue, tiredness
• Weakness
• Decreased urine output
• General swelling

When gently pressing with the hand (palpation) on the chest, there may be a lift produced by the beating of the enlarged right ventricle. Similarly, there a pulse may be felt over the liver.  The liver and spleen may be enlarged.

Listening to the heart with a stethoscope shows a murmur or abnormal sounds. Ascites (collection of fluid in the abdomen associated with liver disorders) may be present.

An ECG or echocardiogram may show enlargement of the right side of the heart.

Doppler echocardiography or right-sided cardiac catheterization are used to measure blood pressures inside the heart and lung.