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 important for estimating severity and for deciding which measurement method fits the available data.
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 a useful reference method 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 severe stenosis or for selected patients with very severe disease and favorable valve anatomy.
Mitral stenosis decisions depend on the valve area, but the number is often derived from different measurement methods depending on study quality and clinical setting. This calculator lets you compare pressure half-time, Gorlin, and planimetry so the same case can be interpreted with the method that fits the available data.
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.
Pressure half-time is convenient because it comes directly from Doppler data, but it is sensitive to changes in compliance and flow conditions. Gorlin is more invasive and is usually used when catheterization data are already available. Planimetry is the most direct approach when the valve orifice is visible clearly enough to trace.
The area thresholds matter most when you compare them with symptoms and valve morphology. A small valve area with favorable anatomy can point toward balloon valvuloplasty, while heavy calcification or subvalvular disease may make surgery more appropriate.
Indexing the area to body surface area can be useful in very small or very large patients, but the unindexed area is still the main severity metric in most clinical discussions.
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This page offers three worksheet-style ways to estimate mitral valve area: pressure half-time, Gorlin, or planimetry. It is meant to help compare measurements and their assumptions, not to replace a full valve-disease workup or procedural decision.
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.
Planimetry is direct tracing of the mitral orifice area in the parasternal short-axis 2D view at the valve tip level. It is considered a 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.