Tricuspid stenosis

Etiology

It is a rare condition affecting less than 1% of patients in developed nations and approximately 3% of patients worldwide.

Tricuspid stenosis is most often of rheumatic origin and is almost always associated with tricuspid regurgitation or left-heart valve disease – mostly mitral stenosis. Metastatic carcinoid infiltration of the endocardium of the cusps may also cause TS or TR.

Other causes are rare, but include:

• congenital abnormalities
• drug-induced valve disease
• endocarditis with large vegetations 
• Whipple’s disease
• right atrial tumour
• systemic lupus erythematosus (SLE), antiphospholipid antibody syndrome
• iatrogenic causes – pacemaker leads, biopsies, radiation therapy

Pathophysiology

The anatomical changes of rheumatic tricuspid stenosis resemble those in mitral stenosis. It is characterized by diffuse fibrous thickening of the leaflets and fusion of 2-3 commissures. Leaflet thickening usually occurs without calcification and anteroseptal commissure is most commonly involved. 

The TS induces diastolic pressure gradient between RA and RV, which increases during inspiration. This leads to pressure overload of the RA and its enlargement.

‍In consequence, right-sided heart failure without RV dysfunction develops. The RV is usually small and underfilled.

Normal valve area is 4-6 cm2, pressure gradient appears at <2 cm2 and valve area <1,5 cm2 is associated with symptoms.

Clinical presentation

The main symptoms are usually caused by other valvular lesions (MS,TR). Symptoms related to the TS are generally caused by congestion before the right heart and low cardiac output of RV. 

• fluttering discomfort in the neck – presystolic “giant a waves” seen in the jugular venous pulse, slow y descent due to delayed emptying of the RA into RV
• jugular venous distention, increasing with inspiration (Kussmaul sign)
• fatigue, exertional syncope
• hepatic congestion – pain in the abdominal right upper quadrant
• leg oedema, ascites

Auscultation

TS is often inaudible but may produce a soft opening snap and a mid-diastolic rumble with presystolic accentuation. The murmur becomes louder and longer with maneuvers that increase venous return (leg-raising, exercise, inspiration).

Echocardiography

Tricuspid stenosis is often overlooked and needs careful evaluation. There is no generally accepted grading score for TS severity.

1) Tricuspid valve morphology

The tricuspid valve complex is similar to the mitral valve but has greater variability. It consists of the 3 leaflets, annulus, chordae tendineae, RV and papillary muscles. The tricuspid valve is located between the RA and the RV and is placed in a slightly more apical position than the mitral valve.

The tricuspid valve is best visualised using the:

• PLAX of RV inflow
• PSAX at the level of the aortic valve
• apical 4 chamber view
• subcostal views
• TOE – 4 chamber view at 0 degree in the basal transoesophageal and oesogastric junction

The hallmark for the diagnosis is diastolic doming of the tricuspid valve seen in the parasternal short-axis view or in the apical four-chamber view.

The leaflet base has more mobility than the restricted and fused leaflet tips, the leaflet then appears to ‘dome’ = bulges towards the RV as blood is caught in the leaflet.

Other findings:

• thickened and distorted leaflets
• limited leaflet mobility
• reduced separation of the leaflet tips

Video 1 Severe thrombotic stenosis of Tricuspid mechanical valve prosthesis

‍Video 2  Severe tricuspid stenosis, PSAX view - severely stenotic valve with thickened and deformed leaflets is seen adjacent to the cross section of AV. Reduced mobility and separation of the leaflets is also apparent. On the right side - Colour Doppler is applied and shows increased flow velocities across the TV.

https://echocardia.com/en/searchassist.html#s=Tricuspid%20valve%20stenosis%20&ps=17688&pa=306&f=1-1-1-1-2-9-5+2.mp4&browse=306

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2) Mean transvalvular pressure gradient

Continuous wave Doppler (CW) is used to measure transvalvular velocities that are derived to gradients, using the Bernoulli equation.

The Doppler line needs to be aligned parallel to tricuspid valve inflow, usually from the apical four chamber view but any view with good visualization of the flow can be used, and go through the vena contracta (the narrowest part of the jet).

First use Colour Doppler for better guidance of the sample line. All Doppler measurements should be made during inspiration, when the velocities across the valve are greatest.

Maximal velocity is measured at the peak of E-wave (in sinus rhythm) and corresponds to the maximal gradient. This velocity is highly variable depending on heart rate and stroke volume.

The mean gradient is calculated from mean velocity of the tracing, it is easy to obtain and reproduce. The gradient can be measured by tracing the dense outline of tricuspid inflow and the mean pressure gradient is automatically calculated.

The mean gradient is usually lower in TS than in MS, ranging between 2-10 mmHg. Mean gradient ≥ 5 mmHg at a heart rate of 70 bpm is considered as a clinically significant tricuspid stenosis. Mean gradient exceeding 10 mmHg suggest severe TS.

Image 1  CW Doppler measurement of transvalvular velocities in severe TS - dense signal of the spectral curve is traced and a mean pressure gradient was calculated to 11.94 mmHg.

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3) Tricuspid valve area 

Estimating tricuspid valve area using echocardiography is not as well-established as estimating mitral valve area.

The most used method to estimate the area in cm2 is:

TVA=190/PHT (in mitral stenosis it is 220/PHT), but the continuity equation or PISA can be also applied to TV.

Pressure half-time (P½t)

Pressure half-time method is based on the assumption that the rate at which the gradient drops during diastole corresponds to the severity of tricuspid stenosis. The bigger the orifice is, the faster will the RV fill and the more quickly the gradient will drop.

In TS, the time it takes for early trans-tricuspid velocity to fall by half is prolonged.

A T ½ values greater than 190 ms are associated with significant or even critical stenosis.

How is it measured?

Acquire an apical four chamber view of the TV and use the CW Doppler. Measure the slope from the maximal inflow velocity at early diastolic filling, align the calipers to the curve and the scanner will automatically derive the pressure half-time.

Image 2 Findings indicative of significant TS

Baumgartner H, Hung J, Bermejo J, et al. American Society of Echocardiography; European Association of Echocardiography. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. J Am Soc Echocardiogr. 2009 Jan;22(1):1-23.

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‍Management of TS

Tricuspid stenosis is a mechanical disorder that is most effectively treated by valve intervention – valve repair or more frequently valve replacement. 

1) Percutaneous balloon valvotomy has been performed in a limited number of patients, as it usually induces significant regurgitation. Isolated, symptomatic severe TS without accompanying TR is an extremely rare condition for which percutaneous balloon tricuspid commissurotomy might be considered.

2) Medical treatment with loop diuretics may help reduce symptoms of systemic and hepatic congestion. Be careful in patients with low output state, as the diuretic therapy further decreases preload.

3) Surgical intervention is usually carried out at the time of intervention on the other damaged valves in patients who remain symptomatic on medical therapy. Surgery is also indicated in symptomatic patients with isolated severe tricuspid stenosis.

The choice between repair or valve replacement depends on valve anatomy and surgical expertise. The absence of pliable leaflet tissue is the main limitation for conservative techniques, but should be attempted when reasonable. These include:

• open valvotomy and commissurotomy
• annuloplasty
• leaflet augmentation with a pericardial patch
• papillary muscle split

Tricuspid valve replacement (TVR) has limited data available on efficacy and outcomes of tricuspid valve surgery for patients with TS.

TVR has a very high operative mortality (7 – 40%) and 10-year survival rates of 37 – 58%.

Valve replacement is usually performed alongside left-heart valve surgery and biological prostheses are usually preferred over mechanical ones because of the high risk of thrombosis.

Image 3  Indications for tricuspid valve surgery

Vahanian A, Beyersdorf F, Praz F, et al. ESC/EACTS Scientific Document Group. 2021 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2021 Aug 28:ehab395. doi: 10.1093/eurheartj/ehab395. Epub ahead of print. PMID: 34453165.

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‍References

1. CAMM, A. J., LÜSCHER, T. F., & SERRUYS, P. W. (2009). The ESC textbook of cardiovascular medicine. Oxford, Oxford University Press
2. Alec Vahanian, Friedhelm Beyersdorf, Fabien Praz, Milan Milojevic, Stephan Baldus, Johann Bauersachs, Davide Capodanno, Lenard Conradi, Michele De Bonis, Ruggero De Paulis, Victoria Delgado, Nick Freemantle, Martine Gilard, Kristina H Haugaa, Anders Jeppsson, Peter Jüni, Luc Pierard, Bernard D Prendergast, J Rafael Sádaba, Christophe Tribouilloy, Wojtek Wojakowski, ESC/EACTS Scientific Document Group, 2021 ESC/EACTS Guidelines for the management of valvular heart disease: Developed by the Task Force for the management of valvular heart disease of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS), European Heart Journal, 2021;, ehab395, https://doi.org/10.1093/eurheartj/ehab395
3. Golamari R, Bhattacharya PT. Tricuspid Stenosis. [Updated 2020 Sep 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499990/
4. Nelson B Schiller, MD, FACC, FRCP, FASE, Bryan Ristow, MD, FACC, FASE, FACP, Xiushui Ren, MD (2021). Echocardiographic evaluation of the tricuspid valve In I. Susan B Yeon, MD, JD, FACC (Ed.), UpToDate. Retrieved July 31, 2021 from https://www-uptodate-com.ezproxy.is.cuni.cz/contents/echocardiographic-evaluation-of-the-tricuspid-valve?sectionName=TRICUSPID%20STENOSIS&search=tricuspid%20stenosis&topicRef=8136&anchor=H5&source=see_link#H5
5. Ferande Peters, MBBCH FCP(SA) FESC FACC FRCP (2021). Tricuspid stenosis. In I. Susan B Yeon, MD, JD, FACC (Ed.), UpToDate. Retrieved July 31, 2021 from https://www-uptodate-com.ezproxy.is.cuni.cz/contents/tricuspid-stenosis?search=tricuspid%20stenosis&source=search_result&selectedTitle=1~74&usage_type=default&display_rank=1
6. Tricuspid Stenosis - Cardiovascular Disorders - MSD Manual Professional Edition. The Trusted Provider of Medical Information since 1899 [online]. Copyright © 2021 Merck Sharp [cit. 31.07.2021]. Accessible at: https://www.msdmanuals.com/professional/cardiovascular-disorders/valvular-disorders/tricuspid-stenosis
7. Cevasco M, Shekar PS. Surgical management of tricuspid stenosis. Ann Cardiothorac Surg. 2017;6(3):275-282. doi:10.21037/acs.2017.05.14

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