Mitral Valve Area Calculator (pressure half-time, MVA = 220 ÷ PHT)

Understanding the mitral valve area calculator (pressure half-time) — concept and principle

This calculator estimates the area of a narrowed (stenotic) mitral valve from the pressure half-time measured on Doppler echocardiography, using Hatle's formula, and grades severity by area and by mean gradient. It is used by cardiologists and sonographers assessing mitral stenosis.

220 ÷ pressure half-time: with the default inputs the result is 1.16 cm² (moderate (1.0–1.5)).

How it is calculated

Mitral valve area (cm²) = 220 ÷ pressure half-time (ms)

The pressure half-time (PHT) is the time for the peak pressure gradient across the valve to fall to half, measured on the continuous-wave Doppler trace of mitral inflow.
Grading by area: over 1.5 cm² mild, 1.0–1.5 moderate, under 1.0 severe.
Grading by mean gradient (at 60–80 bpm): under 5 mmHg mild, 5–10 moderate, over 10 severe. Enter 0 to skip.

The principle

In diastole blood flows from the left atrium into the ventricle. With a tight valve the atrium empties slowly, so the pressure difference between the chambers falls slowly and the half-time is long. Hatle and colleagues found an inverse relation between half-time and valve area in rheumatic mitral stenosis, summarised by the empirical constant 220. The constant depends on how stiff the atrium and ventricle are, which is why it fails in some situations.

Worked example

Default inputs: PHT 190 ms, mean gradient 9 mmHg.

Area = 220 ÷ 190 = 1.158 → 1.16 cm².
1.16 is between 1.0 and 1.5 → Moderate (1.0–1.5 cm²).
Mean gradient 9 is between 5 and 10 → Moderate (5–10 mmHg).

Each point is the calculator re-run with only “Pressure half-time, PHT (ms)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Pressure half-time, PHT (ms)	Mitral valve area (cm²)
47.5	4.63
95	2.32
142	1.54
190	1.16
238	0.93
285	0.77
380	0.58

How to read the result

Where does your result fall?

Area and gradient should point the same way. The gradient depends on heart rate and flow: a fast rate or high output raises it, so the grading assumes 60–80 bpm in sinus rhythm. Severe stenosis with symptoms is usually considered for balloon valvotomy or surgery. Planimetry and the continuity equation are used to cross-check.

Common mistakes

Using PHT just after balloon valvotomy, when chamber compliance changes quickly.
Using PHT with significant aortic regurgitation or a stiff ventricle, which shortens it and overestimates the area.
Applying it to degenerative calcific mitral stenosis, where it is unreliable.

Keep in mind: This is a measurement aid for clinicians, not a diagnosis. Valve disease is assessed with the full echo study.

Frequently asked questions

What is a normal mitral valve area?

About 4–6 cm² in adults; symptoms usually appear when it falls below about 1.5 cm².

Why 220?

It is an empirical constant from studies comparing half-time with catheter-measured area.

How is PHT measured in atrial fibrillation?

Average several beats and avoid short cycles.

Sources: Baumgartner H, Hung J, Bermejo J, et al., "Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice", Eur J Echocardiogr 2009;10:1–25 · Hatle L, Angelsen B, Tromsdal A, "Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound", Circulation 1979;60:1096–1104

Checked 9 Nov 2026. Baumgartner H, Hung J, Bermejo J, et al., “Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice”, Eur J Echocardiogr 2009;10:1–25 (MVA = 220/T½, limitations; Table 9 mitral stenosis severity).

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