Tricuspid Regurgitation (TR) is a heart valve disorder where the valve separating the two right-sided chambers of the heart does not close properly, allowing blood to flow backward. The tricuspid valve is situated between the right atrium and the right ventricle. Its normal function is to prevent blood from flowing back into the atrium when the ventricle contracts to pump blood to the lungs. The prevalence of this condition depends entirely on the level of severity.
Defining the Prevalence of Tricuspid Regurgitation
Mild, or “physiological,” tricuspid regurgitation is an extremely common finding in the general population, often considered a normal variation rather than a disease. Echocardiogram studies performed on people with otherwise healthy hearts reveal that a small amount of backward flow, often termed “trivial” or “trace” TR, is detectable in up to 70% of individuals. This mild form of leakage generally causes no symptoms and has no significant clinical impact on heart function.
The prevalence changes dramatically when considering clinically significant TR, which is typically defined as moderate or severe regurgitation. For the overall adult population, the estimate of moderate or severe TR is significantly lower, affecting a minority of people. However, the occurrence of meaningful TR increases substantially with age; approximately 7% of those aged 75 years and older had moderate or severe TR.
Moderate to severe TR is associated with adverse outcomes. The prevalence of this more serious form is comparable to that of other common valvular diseases like aortic stenosis and mitral regurgitation in the elderly population. This distinction between the near-universal presence of trace TR and the much lower rate of clinically relevant TR highlights why the condition is often under-recognized.
The Primary and Secondary Causes
Tricuspid regurgitation is categorized into two types based on the cause: primary, where the valve itself is structurally damaged, and secondary, where the valve is structurally normal but fails to close due to issues with the surrounding heart chambers. Primary TR is the less common form, accounting for only about 8% to 10% of all TR cases. This type results from direct damage to the valve leaflets, the chordae tendineae, or the annulus.
Primary TR Causes
Specific causes of primary TR include infective endocarditis and conditions like rheumatic heart disease. Trauma to the chest or congenital defects, such as Ebstein’s anomaly, can also directly compromise the valve’s structure. Furthermore, the placement of transvenous pacemaker or defibrillator leads that traverse the valve can injure the leaflets.
Secondary, or functional, TR is the most frequent etiology for moderate or severe cases. In this scenario, the tricuspid valve leaflets are initially healthy, but the surrounding right ventricle (RV) and tricuspid annulus become enlarged. This dilation causes the valve leaflets to be pulled apart, preventing them from closing tightly.
The most common trigger for this right-sided chamber dilation is elevated pressure or volume overload originating from the left side of the heart or the lungs. For example, heart failure involving the left ventricle or significant mitral valve disease increases pressure in the pulmonary circulation. This strains and enlarges the right ventricle, leading to the functional failure of the tricuspid valve.
Identifying Symptoms and Severity Levels
The severity of tricuspid regurgitation is graded as trace, mild, moderate, or severe. Trace or mild TR is overwhelmingly asymptomatic. As severity progresses to moderate or severe, the backward flow of blood into the right atrium causes pressure to build up in the right-sided circulation.
This congestion manifests as symptoms related to right-sided heart failure. Common complaints include peripheral edema (swelling in the legs, ankles, and feet) and fluid accumulation in the abdomen, known as ascites. Individuals may also report persistent fatigue or weakness, as the heart is unable to effectively pump blood forward for oxygenation.
In severe cases, the liver can become congested and enlarged. A noticeable pulsation in the neck veins may also be visible due to the elevated pressure in the jugular veins. The urgency of treatment is directly linked to the severity grade and the presence of these symptoms.
Diagnosis and Treatment Approaches
The primary diagnostic tool for tricuspid regurgitation is the transthoracic echocardiogram (TTE), a non-invasive ultrasound of the heart. This imaging technique allows a clinician to visualize the tricuspid valve’s structure, assess the size and function of the right ventricle, and measure the backward flow of blood, or regurgitant jet. Severity is determined by a comprehensive assessment that includes the size of the regurgitant jet and the overall enlargement of the right heart chambers.
Treatment approaches are tailored to the severity of the TR and the presence of symptoms. For mild or moderate TR in the absence of symptoms, the typical approach is careful monitoring with regular echocardiograms. Medical management frequently involves the use of diuretics, which help the body eliminate excess fluid and reduce the congestion associated with right-sided heart failure.
When TR becomes severe and symptomatic, interventional treatment is usually considered. Traditionally, this meant open-heart surgery to repair or replace the damaged valve. Newer, less invasive transcatheter techniques, such as transcatheter edge-to-edge repair, are increasingly used to treat high-risk patients by repairing the valve without major surgery.