Mitral valve area by the pressure half-time method does not correlate with mean gradient in mitral valve repair patients

Abstract

Pressure half-time is an inaccurate measure of mitral valve area in many clinical situations. The utility of the pressure half-time method to calculate mitral valve area after mitral valve repair is not well defined. Forty-two patients with a repaired mitral valve were identified. Mitral valve area was calculated by both the pressure half-time method and the continuity equation. The two mitral valve areas were then directly compared and also correlated with mean gradient. The two mitral valve areas were significantly different from one another with a mean of 1.81 ± 0.53 cm(2) by continuity equation and 2.65 ± 0.69 cm(2) by pressure half-time. The continuity equation correlated well with mean gradient (ρ = -0.63), whereas the correlation for pressure half-time was weak (r = -0.08). A non-linear, inverse correlation was found between mitral valve area by the continuity equation and mean gradient. No correlation was found between the pressure half-time method for mitral valve area and mean gradient. The continuity equation likely provides a better estimate of mitral valve area in repaired mitral valves.