Can the proximal isovelocity surface area method calculate stenotic mitralvalve area in patients with associated moderate to severe aortic regurgitation? - Analysis using low aliasing velocity of 10% of the peak transmitralvelocity

To assess the ability of the proximal isovelocity surface area (PISA) metho d to accurately measure the stenotic mitral valve area (MVA), and to assess whether aortic regurgitation (AR) affects the calculation, we compared the accuracy of the PISA method and the pressure half-time (PHT) method for de termining MVA in patients with and without associated AR by using two-dimen sional echocardiographic planimetry as a standard. The study population con sisted of 45 patients with mitral stenosis. Seventeen of the 45 patients ha d associated moderate-to-severe AR. The PISA method was performed using low aliasing velocity (AV) of 10% of the peak transmitral velocity, which prov ided the most accurate estimation of MVA when compared with planimetry. The maximal radius r of the PISA was measured from the orifice to blue-red ali asing interface. Using the PISA method, MVA was calculated as (2 pir(2)) x theta / 180 x AV/Vmax, where theta was the inflow angle formed by mitral le aflets, AV was the aliasing velocity (cm/sec), and Vmax: was the peak trans mitral velocity (cm/sec). MVA by the PISA method correlated well with plani metry both in patients with AR (r = 0.90 P < 0.001, SEE = 0.17 cm(2)) and w ithout AR (r = 0.92, P < 0.001, SEE = 0.16 cm(2)). However, MVA by the PHT method did not correlate as well with planimetry (r = 0.57, P < 0.05 SEE = 0.37 cm(2)) in patients with associated AR, and the PHT method produced a s ignificant overestimation (24%) of MVA obtained by planimetry in these pati ents. We conclude that the PISA method allows accurate estimation of MVA an d is not influenced by AR.