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Echo Reference › Mitral Stenosis

Echo Reference — Valve Stenosis

Mitral Stenosis

Severity grading by mean gradient, mitral valve area, and pressure half-time. Wilkins and Padial scoring systems for percutaneous mitral commissurotomy suitability. MVA calculator by pressure half-time method.

Reference Tables MVA Calculator

Severity Grading

MS severity is assessed by mitral valve area (planimetry is the reference method), mean transmitral gradient, and pulmonary artery systolic pressure. Gradients are flow- and rate-dependent — always record heart rate when reporting gradients. In atrial fibrillation, average measurements over ≥ 5 beats with similar R-R intervals.
Parameter Mild Moderate Severe
MVA (cm²) > 2.5 1.6 – 2.5 ≤ 1.5
Mean gradient (mmHg)* < 5 5 – 9 ≥ 10
PHT (ms) < 100 100 – 149 ≥ 150
PASP (mmHg) < 30 30 – 49 ≥ 50

*At normal heart rate (60–80 bpm). Gradients increase significantly with tachycardia, exercise, pregnancy, and high-output states.

Methods for MVA Assessment

Method Technique Key Considerations
2D Planimetry Direct tracing of the mitral orifice in the parasternal short-axis view at the leaflet tips in early diastole Reference standard. Independent of haemodynamic conditions. Requires careful scan plane — must be at the smallest orifice, not at annular level. Can be difficult with heavy calcification.
Pressure half-time (PHT) MVA = 220 ÷ PHT (ms). PHT measured from the CW Doppler E-wave deceleration slope. Quick and reproducible. Inaccurate immediately post-valvotomy, with significant AR (shortens PHT → overestimates MVA), atrial septal defect, or severely abnormal LA/LV compliance.
Continuity equation MVA = (LVOT area × LVOT VTI) ÷ MV VTI Alternative when planimetry and PHT are unreliable. Requires accurate LVOT measurements. Not valid with significant MR (overestimates inflow).
3D Planimetry Multiplanar reconstruction of the mitral orifice from 3D dataset Avoids oblique plane error of 2D. Preferred when available. Requires adequate image quality.

Wilkins Score — PBMC Suitability

The Wilkins (Massachusetts General Hospital) score assesses mitral valve morphology to predict the likelihood of a successful percutaneous balloon mitral commissurotomy (PBMC). Each of four components is scored 1–4, giving a total score of 4–16. A score ≤ 8 is considered favourable for PBMC.

Component 1 2 3 4
Leaflet mobility Highly mobile valve with restriction of only the leaflet tips Mid and base of leaflets have normal mobility Valve continues to move forward in diastole, mainly from the base No or minimal forward movement of the leaflets in diastole
Leaflet thickening Leaflets near normal thickness (4–5 mm) Mid-leaflet normal, considerable thickening at margins (5–8 mm) Thickening extending through entire leaflet (5–8 mm) Considerable thickening of all leaflet tissue (> 8–10 mm)
Calcification Single area of increased echo brightness Scattered areas of brightness confined to leaflet margins Brightness extending into mid-portion of the leaflets Extensive brightness throughout much of the leaflet tissue
Subvalvular thickening Minimal thickening just below the mitral leaflets Thickening of chordae extending to one-third of chordal length Thickening extending to the distal third of the chordae Extensive thickening and shortening of all chordal structures extending to the papillary muscles
Total Score PBMC Suitability Expected Outcome
≤ 8 Favourable High likelihood of successful commissurotomy with good MVA gain and low complication rate
9 – 11 Intermediate Moderate success rate. Consider on a case-by-case basis depending on specific morphological features and surgical risk.
≥ 12 Unfavourable Low likelihood of durable success. Surgical intervention (repair or replacement) preferred.

Padial Score — Commissural Morphology

The Padial score supplements the Wilkins score by specifically assessing commissural morphology, which is the primary determinant of acute PBMC success. Commissural calcification is the strongest predictor of a poor result — even patients with an otherwise favourable Wilkins score may have a suboptimal outcome if commissural calcification is severe.

Component 0 1 2 3
Commissural calcification No calcification Calcification of one commissure Calcification of both commissures (not severe) Severe calcification of both commissures
Commissural fusion severity No fusion (unlikely in true MS) Partial fusion of one commissure Complete fusion of one or partial fusion of both Complete fusion of both commissures
Integration: The Wilkins and Padial scores should be used together. A Wilkins score ≤ 8 with no or mild commissural calcification (Padial 0–1) represents the ideal PBMC candidate. A Wilkins score ≤ 8 but with severe commissural calcification (Padial 3) may still have a suboptimal result despite the apparently favourable overall morphology.

MVA Calculator — Pressure Half-Time

MVA by Pressure Half-Time

MVA = 220 ÷ PHT. Enter the pressure half-time from the CW mitral inflow Doppler. Mean gradient and heart rate are optional but recommended for context.

Pressure Half-Time —
MVA (by PHT) —
Severity —
Mean Gradient —
Heart Rate —

Clinical Context

Gradient–Rate Dependence

Transmitral gradient is highly dependent on heart rate and cardiac output. In a patient with moderate MS (MVA ~1.2 cm²), the mean gradient may be < 5 mmHg at rest with a heart rate of 65 bpm but > 15 mmHg during exercise or with a heart rate of 110 bpm. Always record heart rate alongside gradients. Exercise echo is valuable when resting gradients are discordant with symptoms.

PHT Limitations

Scenario Effect on PHT Impact on MVA Estimate
Significant aortic regurgitation Shortens PHT (AR raises LV diastolic pressure, accelerating LA–LV equalisation) Overestimates MVA → underestimates MS severity
Severely abnormal LV compliance Shortens PHT Overestimates MVA
Atrial septal defect Shortens PHT (LA decompresses via ASD) Overestimates MVA
Immediately post-PBMC or commissurotomy PHT unreliable for days to weeks (LA compliance changing) Use planimetry. PHT normalises over time.
Severe tachycardia E and A waves fuse; PHT difficult to measure accurately Rate control before quantification when possible

Measurement Pitfalls

Pitfall Impact
Planimetry at wrong level Measuring above the leaflet tips (at annular level) overestimates MVA. The orifice must be traced at the smallest opening — the leaflet tips in early diastole.
Oblique parasternal short-axis plane An oblique cut through the valve overestimates the orifice area. Use careful angulation and confirm with orthogonal views or 3D.
Not reporting heart rate with gradients A mean gradient of 8 mmHg at HR 65 has a completely different meaning than at HR 110. Gradients without heart rate are uninterpretable.
Ignoring associated lesions Coexisting MR increases transmitral flow and gradients for a given MVA. Coexisting AR shortens PHT. Always report associated valve lesions.

References

  1. Baumgartner H, et al. Echocardiographic Assessment of Valve Stenosis: EAE/ASE Recommendations for Clinical Practice. J Am Soc Echocardiogr. 2009;22(1):1–23.
  2. Otto CM, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease. Circulation. 2021;143(5):e72–e227.
  3. Vahanian A, et al. 2021 ESC/EACTS Guidelines for the Management of Valvular Heart Disease. Eur Heart J. 2022;43(7):561–632.
  4. Wilkins GT, et al. Percutaneous Balloon Dilatation of the Mitral Valve: An Analysis of Echocardiographic Variables Related to Outcome and the Mechanism of Dilatation. Br Heart J. 1988;60(4):299–308.
  5. Padial LR, et al. Echocardiography Can Predict the Development of Severe Mitral Regurgitation After Percutaneous Mitral Valvuloplasty by the Inoue Technique. Am J Cardiol. 1999;83(8):1210–1213.
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