RESUMO
BACKGROUND: The pressure half time (PHT) method is unreliable for measurement of mitral valve area (MVA) immediately after valvotomy. The proximal isovelocity surface area (PISA) method has been used to derive mitral valve area in patients with mitral stenosis. The aim of our study was to compare PISA method and PHT method in patients undergoing percutaneous balloon mitral valvotomy (BMV). METHODS: The PISA was recorded from the apex and MVA was calculated using continuity equation by the formula 2pir(2) Vr/Vm, where 2pir(2) is the hemispheric isovelocity area, Vr is the velocity at the radial distance "r" from the orifice, and Vm is the peak velocity. A plain angle correction factor (theta)/180 was used to correct the inlet angle subtended by leaflet tunnel as a result of leaflet doming. RESULTS: MVA calculated using PISA method (r = 0.5217, P < 0.0001, SE = 0.016) and PHT (r = 0.6652, P < 0.0001, SE = 0.017) correlated well with 2D method in patients with mitral stenosis before BMV. After BMV, MVA by PISA method correlated well with 2D planimetry (r = 0.5803, P < 0.0001, SE = 0.053) but PHT showed poor correlation (r = 0.1334, P = 0.199, SE = 0.036). The variability of measurement of MVA was most marked with PHT method in the post-BMV period. CONCLUSION: The PISA method correlates well with 2D planimetry in patients with mitral stenosis before and after BMV and is superior to the PHT method in the post-BMV period where the latter may be unreliable.