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Tricuspid insufficiency (TI), a valvular heart disease also called tricuspid regurgitation (TR), refers to the failure of the heart's tricuspid valve to close properly during systole. As a result, with each heart beat some blood passes from the right ventricle to the right atrium, the opposite of the normal direction. Tricuspid regurgitation occurs in roughly less than 1% of people and is usually asymptomatic.
Although congenital causes of tricuspid insufficiency exist, most cases are due to dilation of the right ventricle. Such dilation leads to derangement of the normal anatomy and mechanics of the tricuspid valve and the muscles governing its proper function. The result is incompetence of the tricuspid valve. Left ventricular failure is, in turn, the most common cause of right ventricular dilation. Other common causes of right ventricular dilation include right ventricular infarction, inferior myocardial infarction and cor pulmonale.
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. It is usually accompanied by mitral and aortic valvular disease. Another condition directly harming the valve is tricuspid endocarditis.
Other infrequent causes of tricuspid regurgitation include:
- Carcinoid tumors, which release a hormone which damages the valve
- Connective tissue diseases such as Marfan syndrome
- Systemic lupus erythematosus
- Myxomatous degeneration
- Rheumatoid arthritis
- Radiation therapy
Another important risk factor for tricuspid regurgitation is use of the diet medications called "Fen-Phen" (phentermine and fenfluramine) or dexfenfluramine
Symptoms and Signs 
Tricuspid insufficiency may be asymptomatic, especially if right ventricular function is well preserved. Symptoms are generally those of right-sided heart failure, such as ascites, hepatomegaly, edema and jugular venous distension Vague upper abdominal discomfort (from a congested liver), and fatigue (due to diminished cardiac output) can all be present to some degree.
The liver may be enlarged and is often pulsatile (the latter finding being virtually diagnostic of tricuspid insufficiency). Peripheral edema is often found. In severe cases, there may be ascites and even cirrhosis (so-called 'cardiac cirrhosis').
Tricuspid insufficiency may lead to the presence of a pansystolic heart murmur. Such a murmur is usually of low frequency and best heard low on the lower left sternal border. It tends to increase with inspiration, and decrease with expiration and Valsalva maneuver. However, the murmur may be inaudible reflecting the relatively low pressures in the right side of the heart. A third heart sound may also be present, also heard best with inspiration at the left lower sternal border. Parasternal heave may be felt along the left lower sternal border as well.
Diagnosis is usually made by echocardiography identifying tricuspid prolapse or flail The finding of a pulsatile liver and/or the presence of prominent CV waves in the jugular pulse is also essentially diagnostic.
The main therapy is treatment of underlying cause. In most cases, surgery is not indicated since the root problem lies with a dilated or damaged right ventricle. Medical therapy with diuretics is the mainstay of treatment. Unfortunately, this can lead to volume depletion and decreased cardiac output. Indeed, one must often accept a certain degree of symptomatic tricuspid insufficiency in order to prevent a decrease in cardiac output. Treatment with medicines to reduce cardiac afterload may also be of benefit but a similar risk of depressed cardiac output applies.
Where surgery has to be performed, the following alternatives are available: