Comparison of orifice area by transthoracic three-dimensional Doppler echocardiography versus proximal isovelocity surface area (PISA) method for assessment of mitral regurgitation

Effective regurgitant orifice area is a useful index of the severity of mitral regurgitation (MR). The calculation of regurgitant orifice area using the proximal isovelocity surface area (PISA) method has some technical limitations. Three-dimensional reconstruction of the MR jet was performed using the Live 3D system on a Sonos 7500 to measure regurgitant orifice area directly in 109 cases of MR. Regurgitant orifice area was also measured by quantitative 2-dimensional echocardiography and by the PISA method. To analyze the shape of the regurgitant orifice, the ratio of the long axis to the short axis of the orifice (the US ratio) was calculated. Regurgitant orifice area on 3-dimensional echocardiography showed an almost identical correlation with that obtained by quantitative echocardiography (r = 0.91, p < 0.0001, slope = 0.97) regardless of the US ratio. It was also significantly correlated with orifice area obtained using the PISA method (r = 0.93, p < 0.0001). However, orifice area on 3-dimensional echocardiography was significantly larger than that obtained using the PISA method in the whole study group and in the 62 cases of MR with US ratios > 1.5, whereas the correlation was almost identical in cases of MR with US ratios <= 1.5. Orifice area obtained using the PISA method also underestimated that obtained by quantitative echocardiography in cases of MR with US ratios > 1.5. Three-dimensional echocardiography provided robust values independent of the eccentricity of the MR jet or of cardiac rhythm. In conclusion, the direct measurement of the regurgitant orifice area of MR with 3-dimensional Doppler echocardiography could be a promising method to overcome the limitations of the PISA method, especially in cases of MR with elliptic orifice shapes. (c) 2006 Elsevier Inc. All rights reserved.