Causes of Primary Tricuspid Regurgitation
Primary tricuspid regurgitation is caused by structural abnormalities of the tricuspid valve apparatus itself, with the most common causes being rheumatic valvulitis, infective endocarditis, carcinoid syndrome, and congenital abnormalities such as Ebstein's anomaly. 1
Definition and Classification
Primary (organic) tricuspid regurgitation refers to regurgitation caused by direct abnormalities of the valve leaflets or subvalvular apparatus, as opposed to secondary (functional) tricuspid regurgitation which results from right ventricular dysfunction and annular dilation with structurally normal leaflets.
Specific Causes of Primary Tricuspid Regurgitation
Inflammatory/Infectious Causes
- Rheumatic valvulitis - historically common cause, often associated with mitral and/or aortic valve disease 1
- Infective endocarditis - particularly in intravenous drug users 1
- Rheumatoid arthritis - can affect tricuspid valve structure 1
Congenital Abnormalities
- Ebstein's anomaly - characterized by apical displacement of the tricuspid valve 1
- Cleft tricuspid valve - often part of atrioventricular canal malformations 1
- Congenitally dysplastic valves - with abnormal leaflet and chordal structures 2
- Tricuspid valve prolapse - excessive movement of leaflets into the right atrium 1
Neoplastic/Metabolic Disorders
- Carcinoid syndrome - causes characteristic fibrous plaques on valve leaflets 1
- Endomyocardial fibrosis - affects subvalvular apparatus 1
Connective Tissue Disorders
- Marfan syndrome - affects valve structure and function 1
- Myxomatous disease - similar to mitral valve prolapse 1
Traumatic/Iatrogenic Causes
- Radiation therapy - can cause fibrosis of valve structures 1
- Trauma - including repeated endomyocardial biopsies 1
- Pacemaker lead-induced damage - rare but can cause significant regurgitation 1
- Iatrogenic valve damage - during cardiac procedures 1
Drug-Induced Causes
- Anorectic drugs - including fenfluramine and phentermine 1
- Previous methysergide therapy - can cause valve fibrosis 1
Pathophysiology
Primary tricuspid regurgitation results from direct structural abnormalities that prevent proper leaflet coaptation during systole. The specific pathophysiologic mechanism varies by etiology:
- Leaflet damage/destruction - as seen in endocarditis or rheumatic disease
- Leaflet tethering - from abnormal chordae or papillary muscles
- Leaflet prolapse - excessive movement into the right atrium
- Annular dilation - can occur as a primary process in some conditions
Clinical Implications
Primary tricuspid regurgitation can lead to right ventricular volume overload, right atrial enlargement, and eventually right heart failure if left untreated. The clinical presentation may include:
- Jugular venous distention with prominent v waves
- Lower extremity edema
- Hepatomegaly with pulsatile liver
- Ascites in advanced cases
- Holosystolic murmur at the left lower sternal border that increases with inspiration
Management Considerations
Management of primary tricuspid regurgitation depends on severity, symptoms, and underlying cause:
- Surgical repair is preferred when feasible for severe symptomatic primary TR 1
- Valve replacement is reasonable for severe TR secondary to abnormal leaflets not amenable to repair 1
- Medical therapy is primarily supportive with diuretics for volume overload
Important Caveats
- Primary tricuspid regurgitation is less common than secondary tricuspid regurgitation
- Multiple etiologies may coexist in the same patient
- Echocardiography is essential for distinguishing between primary and secondary causes
- Early intervention before right ventricular dysfunction develops may improve outcomes
Primary tricuspid regurgitation requires careful evaluation of valve morphology using multiple imaging modalities, particularly echocardiography, to determine the specific cause and guide appropriate management.