Tricuspid & Pulmonary Stenosis Severity Grading

Echo Reference — Valve Stenosis

Tricuspid & Pulmonary Stenosis

Severity grading criteria for tricuspid and pulmonary stenosis. Includes PASP estimation in the presence of RVOT obstruction.

Reference Tables

Tricuspid Stenosis — Severity Grading

Tricuspid stenosis is uncommon and almost always rheumatic in aetiology, typically accompanying mitral stenosis. Carcinoid heart disease is the other important cause. TS is assessed by mean diastolic gradient across the tricuspid valve and by tricuspid valve area. Gradients are low compared to left-sided stenotic lesions due to the low-pressure right heart circuit.

Parameter	Mild	Moderate	Severe
Mean gradient (mmHg)	< 2	2 – 4	≥ 5
TVA (cm²)	—	—	≤ 1.0

PHT for TVA: TVA can be estimated using pressure half-time (TVA = 190 ÷ PHT), analogous to the mitral valve formula but with a different constant. This method has limited validation compared to mitral PHT and should be interpreted alongside the mean gradient and 2D appearance.

Respiratory variation: Tricuspid inflow velocities increase with inspiration and decrease with expiration. Measurements should ideally be taken at end-expiration for consistency, or averaged over the respiratory cycle. In atrial fibrillation, average ≥ 5 consecutive beats.

Associated Findings

In significant TS, look for: RA dilatation (often marked), dilated IVC with reduced collapse, hepatic vein diastolic flow reversal, diastolic doming of the tricuspid leaflets, and restricted leaflet motion. Always assess for coexisting tricuspid regurgitation and mitral stenosis (rheumatic TS rarely occurs in isolation).

Pulmonary Stenosis — Severity Grading

Pulmonary stenosis is predominantly congenital (dome-shaped valvular PS). Acquired PS is rare (carcinoid, post-surgical). Severity is graded by peak instantaneous gradient across the pulmonic valve using CW Doppler. Infundibular (subvalvular) stenosis may coexist and should be identified separately.

Parameter	Mild	Moderate	Severe
Peak velocity (m/s)	< 3.0	3.0 – 4.0	> 4.0
Peak gradient (mmHg)	< 36	36 – 64	> 64

RV hypertrophy: In significant PS, the RV wall thickness increases as a compensatory response to the pressure load. RV hypertrophy (> 5 mm) supports haemodynamically significant obstruction. In long-standing severe PS, RV systolic dysfunction may develop.

Infundibular Stenosis

Dynamic infundibular (subvalvular) obstruction can coexist with valvular PS, particularly in the setting of RV hypertrophy. It produces a late-peaking, dagger-shaped CW Doppler signal distinct from the earlier-peaking valvular gradient. The two gradients should be measured and reported separately where possible, as balloon valvuloplasty addresses valvular but not infundibular obstruction.

PASP Estimation with PS or RVOT Obstruction

The standard PASP equation (PASP = 4v²_TR + RAP) assumes no obstruction between the RV and pulmonary artery. When PS or RVOT obstruction is present, the TR-derived gradient gives RV systolic pressure (RVSP), not PASP. To estimate true PASP, the gradient across the pulmonic valve must be subtracted.

PASP with RVOT Obstruction

RVSP = 4v²_TR + RAP

PASP = RVSP − 4v²_PS

Or equivalently: PASP = 4v²_TR − 4v²_PS + RAP

Clinical significance: Failure to account for RVOT obstruction leads to overestimation of pulmonary pressures. A patient with severe PS and a TR velocity of 4.5 m/s has an RVSP of ~96 mmHg, but if the PS gradient is 64 mmHg, the true PASP is only ~32 mmHg — a normal pulmonary pressure. Always check for RVOT obstruction before interpreting elevated TR velocities as evidence of pulmonary hypertension.

Carcinoid Heart Disease

Carcinoid heart disease characteristically produces right-sided valve involvement with thickened, retracted, and immobile leaflets. The tricuspid valve is most commonly affected (producing TR and/or TS), followed by the pulmonary valve (PR and/or PS). The pathognomonic appearance is shortened, thickened leaflets that are fixed in a semi-open position, producing a combination of stenosis and regurgitation. Left-sided involvement is uncommon unless there is a right-to-left shunt (e.g. patent foramen ovale) or bronchial carcinoid.

References

Baumgartner H, et al. Echocardiographic Assessment of Valve Stenosis: EAE/ASE Recommendations for Clinical Practice. J Am Soc Echocardiogr. 2009;22(1):1–23.
Otto CM, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease. Circulation. 2021;143(5):e72–e227.
Vahanian A, et al. 2021 ESC/EACTS Guidelines for the Management of Valvular Heart Disease. Eur Heart J. 2022;43(7):561–632.

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