Calculate mitral valve area using pressure half-time, Gorlin formula, or planimetry. Classify mitral stenosis severity with indexed MVA.
Mitral stenosis (MS) is a narrowing of the mitral valve orifice that impedes blood flow from the left atrium to the left ventricle during diastole. Most commonly caused by rheumatic heart disease, MS remains a major global health burden, particularly in developing countries. Accurate quantification of mitral valve area (MVA) is essential for determining disease severity and guiding management decisions about balloon valvuloplasty or surgical intervention.
Three methods are commonly used to calculate MVA. The **pressure half-time (PHT)** method, the most widely used echocardiographic approach, calculates MVA as 220 divided by the PHT of the transmitral E-wave deceleration. The PHT represents the time it takes for the peak pressure gradient to fall to half its initial value — a longer PHT indicates more severe obstruction. The **Gorlin formula** uses invasive catheterization data to calculate the valve area from cardiac output, diastolic filling period, and mean gradient. **Planimetry** directly traces the valve orifice area in the short-axis view and is considered the gold standard when image quality is adequate.
A normal mitral valve area is 4.0–6.0 cm². Mild MS is defined as 1.5–2.5 cm², moderate MS as 1.0–1.5 cm², and severe MS as < 1.0 cm². Symptoms typically develop when the MVA falls below 1.5 cm², and intervention is usually considered for symptomatic patients with MVA < 1.5 cm² or asymptomatic patients with very severe stenosis (< 1.0 cm²) and favorable valve anatomy.
Accurate MVA quantification is the cornerstone of mitral stenosis management. This calculator supports all three major methods and provides severity classification to support clinical education and decision-making. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints.
Pressure Half-Time: MVA = 220 / PHT (ms). Gorlin Formula: MVA = CO / (HR × DFP × 37.7 × √ΔP), where CO in mL/min, DFP in seconds, ΔP = mean gradient (mmHg). Indexed MVA = MVA / BSA.
Result: 1.10 cm²
With a pressure half-time of 200 ms, MVA = 220/200 = 1.10 cm², indicating moderate mitral stenosis. Indexed MVA = 1.10/1.8 = 0.61 cm²/m².
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Normal MVA is 4.0–6.0 cm². Mild stenosis: 1.5–2.5 cm², moderate: 1.0–1.5 cm², severe: < 1.0 cm².
PHT may be inaccurate immediately after balloon valvuloplasty (LA compliance changes), in significant aortic regurgitation (alters transmitral pressure decay), and in patients with abnormal LV relaxation or very high/low heart rates. Use this as a practical reminder before finalizing the result.
Planimetry is direct tracing of the mitral orifice area in the parasternal short-axis 2D view at the valve tip level. It is considered the reference method when image quality is adequate.
Treatment is indicated for symptomatic severe MS (MVA < 1.5 cm²). Percutaneous balloon mitral valvuloplasty is preferred if valve morphology is favorable (Wilkins score ≤ 8).
Rheumatic heart disease causes the vast majority of MS worldwide. Rare causes include severe mitral annular calcification, congenital MS, carcinoid, and SLE.
AF is common in MS and causes variable R-R intervals. Average multiple consecutive beats to obtain reliable PHT and gradient measurements.