MVA (Pressure Half-Time)

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.

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.

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.