Understanding Tricuspid Regurgitation: A Comprehensive Patient Guide

Table of Contents

• Introduction: The "Forgotten Valve"
• Heart Anatomy: Understanding the Tricuspid Valve
• Symptoms and Clinical Presentation
• How Common Is Tricuspid Regurgitation?
• Causes and Classification of TR
• Secondary Tricuspid Regurgitation
• Clinical Implications for Patients
• Source Information

Introduction: The "Forgotten Valve"

The tricuspid valve has been called the "forgotten valve" in cardiology because it has historically received less attention than other heart valves. Doctors once believed tricuspid regurgitation (leaky valve) was just a secondary problem that would resolve after treating other heart conditions, particularly mitral valve disease. We now know this isn't true - TR is a serious condition in its own right that requires specific attention.

TR is particularly challenging to diagnose and manage because it typically occurs alongside other medical conditions. Many clinicians have mistakenly viewed it as an "innocent bystander" to more consequential diseases of the left heart and lungs. Without obvious left heart disease, the symptoms of severe TR - including edema (swelling), fatigue, and exercise intolerance - are often mistaken for normal signs of aging, leading to dangerous delays in diagnosis and treatment.

Natural history studies clearly show the need for early diagnosis: survival becomes progressively shorter with increasing severity of TR, even after accounting for other health conditions. Gaps in understanding the disease process, diagnostic challenges, and uncertainty about when to intervene have all contributed to high mortality rates among patients with severe TR, whether they receive medical treatment or not.

Heart Anatomy: Understanding the Tricuspid Valve

Understanding the tricuspid valve's structure helps explain why TR develops and how it affects the heart. The tricuspid valve is actually the largest valve in the heart and typically has three leaflets of unequal size, though some healthy people may have two posterior leaflets instead of three. These leaflets are thinner than those of the mitral valve and are supported by chordae (tendon-like strings) attached to papillary muscles in the right ventricle.

The tricuspid annulus (the ring-like structure that supports the valve) has very little fibrous tissue or collagen. There are important sex-related differences in this anatomy: males have more myocardial cells and elastic fibers, while females have a larger annulus even after accounting for differences in heart or body size. The normal annulus is saddle-shaped and dynamic, larger in early diastole (relaxation phase) and during atrial systole (contraction phase), which allows for large blood volumes to flow under low pressure.

Because of the tricuspid valve's large size, benchtop modeling suggests that only 40% annular dilation may result in clinically significant TR, compared to 75% annular dilation needed for significant mitral regurgitation. This anatomical vulnerability explains why the tricuspid valve is particularly sensitive to changes in the heart's structure and function.

The right coronary artery and the atrioventricular node (which controls heart rhythm) are located very close to the tricuspid annulus. This proximity places these structures at risk during surgical or transcatheter procedures on the valve, with the separation narrowing to less than 3 mm in some areas, making careful procedural planning essential.

Symptoms and Clinical Presentation

Patients with severe tricuspid regurgitation typically present with signs and symptoms of chronic right heart failure. These include:

• Systemic fluid retention leading to elevated jugular venous pressure, peripheral edema (swelling in limbs), and ascites (fluid buildup in abdomen)
• Reduced intestinal absorption and anasarca (generalized swelling throughout the body)
• Decreased cardiac reserve resulting in exercise intolerance, dyspnea (shortness of breath), and poor functional capacity
• Decreased cardiac output with progressive end-organ damage from both venous congestion and inadequate blood flow

End-stage disease is associated with cachexia (wasting syndrome) resulting from poor nutrient absorption, as well as a systemic proinflammatory state. The symptoms of reduced cardiac output are often mistaken for left heart failure, further delaying proper diagnosis of TR.

Although many signs and symptoms of severe TR may initially respond to diuretics (water pills), reduced cardiac output and other neurohormonal changes can lead to serious complications including liver disease (cardiohepatic syndrome) and kidney disease (cardiorenal syndrome). The cardiohepatic syndrome not only increases bleeding risk in TR patients but is also a strong independent predictor of death or hospitalization for heart failure within one year after transcatheter tricuspid valve therapy.

Atrial arrhythmias - particularly atrial fibrillation (AFib) - are common in patients with TR and occur in both newly diagnosed and progressive valvular disease. AFib has been associated with left and right atrial dilatation, annular dilatation, and atrioventricular valvular regurgitation. Rhythm control is associated with a reduction in TR severity, highlighting the importance of managing arrhythmias in these patients.

How Common Is Tricuspid Regurgitation?

As with other valvular heart diseases, the prevalence of tricuspid regurgitation increases with age. While clinically significant valvular disease is diagnosed more frequently in men overall, the prevalence of clinically significant TR may be up to four times higher among women. Female sex is an independent predictor of both the severity and progression of TR.

Although the basis for these sex differences isn't fully understood, the higher female prevalence of heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation may play important roles. Beyond older age, female sex, and atrial fibrillation, other clinical predictors of severe and progressive TR include elevated pulmonary-artery systolic pressure and increased left atrial size, suggesting that both pre- and postcapillary pulmonary hypertension contribute to this process.

The mortality statistics for TR are concerning. Studies of patients with tricuspid regurgitation found that medical management of severe disease was associated with 1-year mortality rates of 42% and 36% respectively. Compared to people with mild or no TR, those with moderate or severe regurgitation had a long-term risk of death from any cause that was increased by a factor of 2.0 to 3.2, even after adjusting for age and sex.

Even mild TR was associated with a nearly 30% increase in all-cause, long-term mortality. A recent study of outcomes for different valve diseases showed that all-cause mortality was higher for TR (hazard ratio 2.74) than for aortic valve disease (hazard ratio 1.62) or mitral valve disease (hazard ratio 1.25). This means patients with TR have significantly worse survival outcomes than those with other common valve conditions.

Morphologic predictors of progressive TR depend on the primary cardiovascular disease process. For patients with pulmonary arterial hypertension, predictors include right ventricular enlargement, increased right ventricular sphericity, tricuspid annular dilatation, and increased tricuspid leaflet tenting area. For patients with atrial fibrillation, the presence of tricuspid-valve tethering, increased left atrial volume, increased tricuspid annular diameter, and right ventricular remodeling predict severe TR.

Rapid progression to severe TR has been independently associated with all-cause mortality. Predictors of rapid progression include the presence of pacemaker or defibrillator leads, mild TR (versus none), tricuspid annular dilatation, and any valvular heart surgery without concomitant tricuspid-valve surgery. In patients who have undergone mitral-valve surgery, the progression of TR is associated with clinical adverse events.

Causes and Classification of TR

TR is now classified according to a refined system that reflects our better understanding of different disease mechanisms and their associated outcomes. The traditional subdivision into primary leaflet disorders and secondary (nonleaflet) disorders has been updated with a more comprehensive classification:

1. Primary Tricuspid Regurgitation (5-10% of cases) - Results from intrinsic valve disease
2. Secondary Tricuspid Regurgitation (approximately 80% of cases) - The valve structure appears normal but doesn't function properly due to other heart changes
3. CIED-related Tricuspid Regurgitation (approximately 10-15% of cases) - Caused by cardiac implantable electronic devices

Primary TR occurs as a result of intrinsic valve disease and can be caused by:

• Congenital anomalies like Ebstein's anomaly (where the valve is displaced downward)
• Infective endocarditis (valve infection)
• Rheumatic disease
• Carcinoid heart disease (from hormone-secreting tumors)
• Toxic effects of chemicals
• Tumors
• Blunt trauma
• Myxomatous degeneration (valve tissue weakness)

The incidence of tricuspid-valve endocarditis is increasing in parallel with increases in intravenous drug use, antibiotic resistance, and use of cardiac implantable electronic devices. A recent meta-analysis of 44 studies including 301 patients undergoing AngioVac-assisted vegetation debulking showed that the vegetation size was reduced by more than 50% in 89.2% of patients.

Other causes of primary TR include traumatic rupture of the tricuspid-valve apparatus from blunt chest trauma - a rare condition that may go undiagnosed until the chronic effects of volume overload cause symptoms of right heart failure. The overall prevalence of TR after heart transplantation is approximately 20% but is highest in the first month after transplantation and decreases over time.

Secondary Tricuspid Regurgitation

In patients with secondary tricuspid regurgitation, the intrinsic structure of the leaflets appears normal, but abnormalities of the right atrium, tricuspid annulus, or right ventricle prevent proper valve closure. Secondary TR has been further subdivided into two main categories:

Atrial Secondary TR (10-25% of secondary TR cases) is characterized by normal-appearing leaflets that fail to coapt (close properly) due to marked annular and atrial dilatation. The leaflets show minimal tethering or tenting, and right ventricular structure and function are typically normal. This type is associated with atrial fibrillation, normal left ventricular ejection fraction (>60%), minimal elevation of pulmonary-artery pressures, and absence of left-side valve disease.

Ventricular Secondary TR involves dilatation of the right ventricle (mainly the midventricular free wall), leading to apical displacement of the papillary muscles and tethering of the tricuspid leaflets. This form is associated with increased pulmonary-artery pressures (≥50 mm Hg) and reduced right ventricular function.

Patients with atrial secondary TR are more often female with normal left ventricular function, while those with ventricular secondary TR are more often male with reduced left ventricular function. The right atrial size is significantly larger in atrial secondary TR, while right ventricular diameter is more enlarged in ventricular secondary TR.

Long-standing atrial secondary TR may also progress to involve right ventricular dilatation, creating a mixed morphologic appearance with leaflet tethering. Understanding these distinctions is important because they may influence treatment decisions and outcomes.

Clinical Implications for Patients

This comprehensive review of tricuspid regurgitation carries several important implications for patients:

Early diagnosis is critical - The high mortality rates associated with TR (36-42% at one year for severe cases treated medically) underscore the importance of recognizing symptoms early. Patients and doctors should be particularly alert to signs of right heart failure - especially swelling, fatigue, and exercise intolerance - and not dismiss them as normal aging.

Women are at higher risk - The finding that women may be up to four times more likely to develop significant TR suggests that female patients and their doctors should be especially vigilant about heart valve health. This increased risk may be related to women's higher prevalence of heart failure with preserved ejection fraction and atrial fibrillation.

Comprehensive evaluation is essential - Because TR often occurs alongside other conditions like atrial fibrillation, left heart disease, and pulmonary hypertension, patients need thorough cardiac evaluation to identify all contributing factors. Treatment must address not just the leaky valve but also these underlying conditions.

Treatment timing matters - The historical approach of ignoring TR during other cardiac surgeries appears misguided given evidence that concomitant TR management improves long-term outcomes. Patients facing heart surgery should discuss tricuspid valve assessment with their cardiac team.

New treatments offer hope - The development of transcatheter tricuspid valve therapies provides less invasive options for high-risk patients who cannot undergo open heart surgery. However, identifying the right timing for intervention remains challenging and requires careful discussion between patients and their heart specialists.

Patients with symptoms suggesting possible TR should seek evaluation by a cardiologist, preferably one with expertise in valvular heart disease. Diagnostic testing typically includes echocardiography (heart ultrasound), which can assess the severity of regurgitation and its impact on heart function. Additional tests like cardiac MRI or right heart catheterization may be needed in some cases.

Source Information

Original Article Title: Tricuspid Regurgitation
Authors: Rebecca T. Hahn, M.D.
Publication: The New England Journal of Medicine, May 18, 2023
DOI: 10.1056/NEJMra2216709

This patient-friendly article is based on peer-reviewed research from Columbia University Irving Medical Center and New York-Presbyterian Hospital. The original work provides a comprehensive review of tricuspid regurgitation, including its anatomy, epidemiology, classification, and clinical implications.