Comparison of proximal isovelocity surface are method with pressure half-time and planimetry in evaluation of mitral stenosis

Objectives. This study sought to 1) compare the accuracy of the proximal isovelocity surface are (PISA) and Doppler pressure half-time methods and planimetry for echocardiographic estimation of mitral valve area; 2) evaluate the effect of atrial fibrillation on the accuracy of the PIS method; and 3) assess factors used to correct PIS are estimates for leaflet angulation. Background. Despite recognized limitations of traditional echocardiographic methods for estimating mitral valve area, there has been no systematic comparison with the PIS method in single cohort. Methods. Are estimates were obtained in patients with mitral stenosis by the Gorlin hydraulic formula, PIS and pressure half-time method in 48 patients and by planimetry in 36. Two different factors were used to correct PIS estimates for leaflet angle (θ): 1) plane-angle factor (θ/180 [θ in degrees]); and 2) solid-angle factor [1 — cos(θ/2)]. Results. After exclusion of patients with significant mitral regurgitation, the correlation between Gorlin and PIS areas (0.88) was significantly greater (p < 0.04) than that between Gorlin and pressure half-time (0.78) or Gorlin and planimetry (0.72). The correlation between Gorlin and PIS are estimates was lower in atrial fibrillation than sinus rhythm (0.69 vs. 0.93), but the standard error of the estimate was only slightly greater (0.24 vs. 0.19 cm2). The average ratio of the solid- to the plane-angle correction factors was approximately equal to previously reported values of the orifice contraction coefficient for tapering stenosis. Conclusions. 1) The accuracy of PIS are estimates in mitral stenosis is at least comparable to those of planimetry and pressure half-time. 2) Reasonable accuracy of the PIS method is possible in irregular rhythms. 3) simple leaflet angle correction factor, θ/180 (θ in degrees), yields the physical orifice are because it overestimates the ven contract are by factor approximately equal to the contraction coefficient for tapering stenosis.