Etiology of Moderate Tricuspid Regurgitation
Moderate tricuspid regurgitation is most commonly secondary (functional) rather than primary, caused by right ventricular dilation, tricuspid annular dilation, or pulmonary hypertension in the setting of structurally normal valve leaflets. 1
Primary (Organic) Causes
Primary tricuspid regurgitation results from structural abnormalities of the tricuspid valve apparatus itself: 2
- Infective endocarditis - particularly common in intravenous drug users 1
- Rheumatic heart disease - often accompanied by left-sided valve disease, especially mitral stenosis 1
- Myxomatous degeneration - leaflet prolapse or flail leaflet 1, 3
- Carcinoid syndrome - causes valve thickening and retraction 1
- Congenital abnormalities - including Ebstein's anomaly and dysplastic valves 1
- Drug-induced valve disease - certain medications can cause valvular damage 1
- Endomyocardial fibrosis 1
- Iatrogenic damage - from cardiac procedures or device placement 1
- Thoracic trauma 1
Secondary (Functional) Causes
Secondary tricuspid regurgitation is far more common and occurs without primary valve pathology, resulting from impaired leaflet coaptation: 1
Left-Sided Heart Disease
- Left-sided valve disease - mitral regurgitation or stenosis causing elevated left atrial pressure and secondary pulmonary hypertension 1, 4
- Left ventricular dysfunction - leading to elevated pulmonary pressures 1
- Ischemic mitral regurgitation - commonly associated with functional TR 4
Right Ventricular Pathology
- Right ventricular dilation - from pressure or volume overload 1
- Right ventricular dysfunction - intrinsic RV disease or cardiomyopathy 1, 5
- Tricuspid annular dilation - the annulus becomes flat and planar rather than saddle-shaped 1
- Papillary muscle displacement and leaflet tethering - from RV remodeling 1
Pulmonary Hypertension
- Primary pulmonary hypertension 1
- Secondary pulmonary hypertension - from left heart disease, chronic lung disease, or pulmonary embolism 1, 5
Atrial Fibrillation
- Longstanding atrial fibrillation - causes progressive annular dilation independent of ventricular dysfunction 1, 6
- AF-induced annular remodeling - present in 70-88% of patients with severe TR 6
Device-Related
- Cardiac implantable electronic device leads - crossing the tricuspid valve can cause leaflet damage or impair coaptation 1
- Pacemaker or ICD leads - may cause direct valve trauma or interfere with leaflet motion 1
Other Causes
- Aging - associated with progressive valve changes 1
- Chronic lung disease - causing RV pressure overload 7
- Congestive heart failure - with elevated right-sided pressures 7
Pathophysiologic Mechanism
The progressive nature of functional TR creates a vicious cycle: 1
- Initial RV dilation or pressure overload causes tricuspid annular dilation
- Annular dilation leads to impaired leaflet coaptation and TR
- TR itself causes further RV volume overload and dilation
- Progressive RV dilation worsens annular dilation and leaflet tethering
- This perpetuates worsening TR severity over time
The tricuspid annular dilation, loss of annular contraction, and increased leaflet tethering are the most important factors in development of functional TR. 1
Clinical Pitfall
A critical misconception is that functional TR will resolve spontaneously after treating the underlying left-sided disease—this has proven incorrect, and TR often persists or progresses even after successful treatment of left-sided lesions. 8, 4 Tricuspid annular diameter ≥40 mm (or ≥21 mm/m²) at the time of left-sided valve surgery predicts persistent or progressive TR and should prompt consideration of concomitant tricuspid repair. 1, 2