MVA (Pressure Half-Time): Estimates Mitral Valve Area from the deceleration of mitral inflow. Standard method for grading Mitral Stenosis.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Evaluation and grading of Mitral Stenosis (MS) severity during transthoracic or transesophageal echocardiography (TTE/TEE).
To monitor progression of native valve or bioprosthetic mitral stenosis.
Do Not Rely on if
Patient has severe Aortic Regurgitation, reduced LV compliance, or if assessed immediately following mitral valvuloplasty. These conditions alter the transmitral pressure gradient independent of the valve area.
Section 2
Formula & Logic
Electrophysiological and Physical Basis
The Pressure Half-Time (PHT) is the time required for the peak transmitral pressure gradient to decline to one-half of its original value. In mitral stenosis, the time it takes for the pressure in the left atrium to equilize with the left ventricle is prolonged because the stenotic valve orifice restricts flow.
The 220 Constant
Empirically, a PHT of 220 ms has been found to correspond to a Mitral Valve Area (MVA) of 1.0 cm2. Thus, MVA = 220 / PHT.
Severity Grading (ASE)
01
Mild MS: MVA > 1.5 cm2 (PHT < 150 ms)
02
Moderate MS: MVA 1.0–1.5 cm2 (PHT 150–220 ms)
03
Severe MS: MVA < 1.0 cm2 (PHT > 220 ms)
Section 3
Pearls/Pitfalls
Confounding Factors
If left ventricular compliance is reduced (e.g., in elderly patients with LVH/HTN), the PHT will be shortened, falsely underestimating the severity of MS. Conversely, if LA compliance is increased, the PHT will be lengthened.
Gold Standard
Planimetry of the mitral valve in the short-axis view remains the anatomical gold standard for MVA, but can be technically difficult and requires excellent image quality.
Section 4
Evidence Appraisal
Refining the Measurement
Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound.
Hatle L et al. • Circulation.. 1979;60(5):1096-104. The original paper that popularized the PHT method.
Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice.
Baumgartner H et al. • J Am Soc Echocardiogr.. 2009;22(1):1-23. Established the modern thresholds for severity.