tricuspid stenosis

**Etiology** - Rheumatic heart disease (most common): nearly always coexists with mitral stenosis (and often aortic valve disease); isolated TS is rare. Rheumatic TS is usually accompanied by tricuspid regurgitation. - Carcinoid syndrome/heart disease: plaque-like fibrous deposits (serotonin and other mediators) on right-sided valves, causing TR more often than TS, plus pulmonic stenosis/regurgitation. Typically occurs with liver metastases, because the liver otherwise inactivates the mediators. - Congenital tricuspid atresia/stenosis. - Rare: infective endocarditis with large vegetations, right atrial myxoma or other tumor obstructing inflow (mimic), endomyocardial fibrosis, Fabry disease, Whipple disease, methysergide/ergot-type drugs, pacemaker lead–related fibrosis, and prior radiation.

**Pathophysiology** - Narrowed orifice creates a diastolic pressure gradient between the RA and RV (a mean gradient of ≥5 mmHg is considered significant). - The right atrium dilates and RA pressure rises, causing systemic venous congestion: elevated JVP, hepatomegaly (congestive hepatopathy), ascites, edema, and fatigue/low cardiac output from reduced RV preload. - Because RV filling is reduced, pulmonary congestion is relatively spared, even when concurrent mitral stenosis is present. Dyspnea may therefore be less prominent than expected with mitral stenosis, which is a classic clue.

**Clinical features** - Symptoms: fatigue, abdominal discomfort or fullness, ascites, edema, neck pulsations/fullness; low cardiac output symptoms. - JVP: large, prominent 'a' waves (forceful RA contraction against stenotic valve) if in sinus rhythm; slow y descent. Absent 'a' waves with atrial fibrillation. - Auscultation: diastolic rumbling murmur at the left lower sternal border (and sometimes an opening snap), which increases with inspiration (Carvallo sign, as with other right-sided murmurs) and is louder during inspiration because of increased venous return. Murmur is often confused with that of mitral stenosis. - Other: pulsatile liver (if associated TR), hepatomegaly, ascites, anasarca; jaundice and cardiac cirrhosis in long-standing disease.

**Diagnosis** - Echocardiography is the test of choice: thickened, doming leaflets with restricted opening, reduced valve area, elevated mean diastolic gradient (≥5 mmHg), and dilated RA/IVC. Pressure half-time is used to estimate valve area. - ECG: right atrial enlargement (tall peaked P waves in lead II, >2.5 mm, and in V1), with no RVH (unless other lesions coexist); may show atrial fibrillation. - CXR: enlarged right heart border/RA, dilated SVC and azygos vein, with clear lung fields. - Cardiac catheterization is rarely required.

**Management** - Diuretics and sodium restriction for congestion. - Treat the underlying cause (e.g., rheumatic fever prophylaxis with penicillin, somatostatin analogs such as octreotide for carcinoid). - Intervention for severe, symptomatic TS: valve repair/replacement (surgical), often done at the time of left-sided valve surgery for mitral disease; percutaneous balloon valvuloplasty is an option in selected cases (but can cause significant TR). Bioprosthetic valves are generally preferred over mechanical valves because of the high thrombosis risk in the low-pressure right-sided circuit.

**High-yield comparisons / USMLE pearls** - Right-sided murmurs increase with inspiration; left-sided murmurs increase with expiration. - Diastolic rumble at LLSB that increases with inspiration + giant 'a' waves in a patient with rheumatic mitral valve disease = tricuspid stenosis. - Ebstein anomaly (lithium exposure in utero, atrialized RV) causes TR, not TS. Tricuspid atresia presents with cyanosis, an ASD/VSD, and left axis deviation (a classic ECG finding), and is fed by a PDA until closure. - Carcinoid heart disease: right-sided valve lesions (TR > TS, pulmonic stenosis) because mediators are inactivated by the lungs (MAO) before reaching the left heart (except in bronchial carcinoid or right-to-left shunt). - Rheumatic heart valve involvement frequency: mitral >> aortic >> tricuspid >> pulmonic.