Tricuspid stenosis

Tricuspid stenosis (TS) refers to a narrowing of the tricuspid valve.

Tricuspid stenosis (TS) is a rare valvular disorder that is usually caused by rheumatic fever; since rheumatic fever has become less common, so too has TS.

TS leads to two underlying problems:

1. Reduced forward blood flow to the lungs
2. Increased back pressure into the right atrium and venous system.

Treatment is aimed at treating the underlying cause with or without adjunctive medical and surgical treatments if deemed appropriate.

Tricuspid stenosis is now considered rare in the UK.

Rheumatic fever is now rare in the UK, due to:

• Improvements to social conditions and housing conditions,
• Introduction of antibiotics

As a result, tricuspid stenosis is now also considered a rare condition.

Tricuspid stenosis is usually caused by rheumatic fever.

Rheumatic fever

Rheumatic fever is the most common cause of TS. Rheumatic fever damages the heart valves in the following ways:

• The initial infection is usually a bacterial throat infection with group A beta-haemolytic streptococcus.
• In response to the infection, autoantibodies develop which target the heart valves.
• Autoantibodies lead to chronic inflammation of the heart valves.
• Chronic inflammation leads to thickening and calcification of the valves.
• Thickening and calcification lead to narrowing of the valve orifice and relatively fixed and stiff valves.

Rheumatic fever rarely presents with just tricuspid stenosis. This is because it more commonly affects other valves of the heart including the mitral valve and aortic valve. Rheumatic fever can also lead to mixed disease in the tricuspid valve whereby both regurgitation and stenosis are observed.

Other causes

Other causes of tricuspid stenosis are rarer, and include:

• Other medical conditions (e.g. Carcinoid syndrome)
• Iatrogenic causes (e.g. pacemaker lead(s), endomyocardial biopsy, radiotherapy)
• Congenital causes (e.g. tricuspid valve atresia or valve stenosis)

Tricuspid stenosis can lead to increased back pressure in the venous system.

Tricuspid stenosis creates resistance to blood flow from the right atrium to the right ventricle. This leads to three problems:

1. Turbulent blood flow across the valve. This is the cause of the murmur (see Clinical Features below)
2. Increased right atrial pressure. This back pressure is passed on to the vena cava (superior and inferior), which can lead to a raised JVP (with a prominent A-wave, caused by atrial contraction against the stenotic tricuspid valve), ascites, hepatomegaly (which may be painful), and occasionally peripheral oedema.
3. Reduced right ventricular blood flow. This means there is also a reduction in onward blood flow to the lungs.

Tricuspid stenosis classically causes a diastolic murmur.

History

The reduction in forward blood flow through the lungs can cause fatigue.

Examination

The murmur of isolated TS is classically

• Mid-diastolic
• “Low rumbling”
• Best heard in the tricuspid area (4th intercostal space, left sternal edge)
• Loudest on inspiration

There may also be an opening ‘snap’ as the stiff valves mobilises. The murmur of TS is often difficult to elicit because TS rarely presents in isolation. The murmurs of mitral stenosis, aortic stenosis, or tricuspid regurgitation may also be present and mask the murmur of TS.

NOTE: The 'RILE' mnemonic (Right Inspiration, Left Expiration) can help you remember that right-sided murmurs are louder in inspiration.

Echocardiography is the best diagnostic test for tricuspid stenosis.

As with all valve diseases, echocardiography is the best diagnostic tool for tricuspid stenosis. As with tricuspid regurgitation, the specifics of grading valve disease are beyond the scope of a non-specialist. One example of the many measurements used in this process is the tricuspid valve area: A valve area ≤1.0 cm² indicates severe TS. A normal tricuspid valve area is at least 4 cm²

Other incidental findings on chest x-ray (CXR) or ECG can point to the diagnosis of tricuspid stenosis:

• CXR: Right atrial enlargement
• ECG: P-Pulmonale (heightened P wave) associated with right atrial enlargement.

The main treatment options for tricuspid stenosis involve treating the underlying cause and managing co-existent right-heart failure.

Management of symptomatic tricuspid stenosis can be considered in three sections:

1. Treat the Underlying Cause.
2. Medical Treatment for Right-Sided Heart Failure.
3. Surgical Treatment.

Treat the underlying cause

For example, underlying rheumatic fever should be treated.

Medical treatment for right-sided heart failure

Diuretics (e.g. furosemide) can be used for patients with severe tricuspid stenosis and symptoms of right heart failure.

Surgical treatment

There are three options for surgical intervention:

1. Percutaneous balloon valvotomy
2. Surgical valve repair
3. Surgical valve replacement

Surgical interventions tend to be offered to patients with severe TS, or if patients are undergoing cardiac surgery for other valve pathologies (e.g. mitral stenosis). The decision as to which specific type of surgical intervention is offered is patient- and specialist-dependent.

Limited prognostic data is available because of the rarity of tricuspid stenosis.

Ultimately, the prognosis will depend on the specific cause of underlying tricuspid stenosis and any co-existing valve lesions.

Last updated: September 2024

References:

• UpToDate. Tricuspid stenosis.

• Weerakkody, Y. et al. Tricuspid valve stenosis. Reference article, Radiopaedia.org (Accessed on 16 May 2024) https://doi.org/10.53347/rID-28791