Abstract
Despite a small army of quantitative metrics, the accurate and reproducible assessment of mitral regurgitation (MR) severity can be a challenge for any echocardiographer. The proximal isovelocity surface area (PISA) method is one metric being examined with renewed interest in the current era of advanced three-dimensional (3D) color Doppler imaging. In theory, flow accelerating towards a regurgitant orifice will form a series of concentric isovelocity shells, each smaller in surface area and higher in velocity as they approach the orifice. If the orifice is a very small circle then the shells will be hemispheres. By calculating the shell area from its radius (r) and multiplying by its velocity (the color Doppler aliasing velocity) the regurgitant flow rate and effective regurgitant orifice area (EROA) can be calculated as; 2πr2 x aliasing velocity/peak regurgitant velocity. 1 Zoghbi W.A. Enriquez-Sarano M. Foster E. Grayburn P.A. Kraft C.D. Levine R.A. et al. Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. J Am Soc Echocardiogr. 2003; 16: 777-802 Abstract Full Text Full Text PDF PubMed Scopus (3328) Google Scholar A well recognized limitation of this flow convergence method is that most clinical MR occurs through an irregularly shaped regurgitant orifice with a PISA geometry that is not hemispheric. Recently, 3D color Doppler has been employed to image the zone of flow convergence and has clearly depicted the error inherent in two-dimensional (2D) geometric assumptions of the flow convergence region. 2 Matsumura Y. Saracino G. Sugioka K. Tran H. Greenberg N.L. Wada N. et al. Determination of regurgitant orifice area with the use of a new three-dimensional flow convergence geometric assumption in functional mitral regurgitation. J Am Soc Echocardiogr. 2008; 21: 1251-1256 Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar , 3 Little S.H. Igo S.R. Pirat B. McCulloch M. Hartley C.J. Nose Y. et al. In vitro validation of real-time three-dimensional color Doppler echocardiography for direct measurement of proximal isovelocity surface area in mitral regurgitation. Am J Cardiol. 2007; 99: 1440-1447 Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar Degenerative MR, with calcified or prolapsing leaflets, may occur through a nearly circular (or at least oval) regurgitant orifice. In contrast, functional MR—which is caused by left ventricular systolic dysfunction with chordal tethering—is typically associated with a crescent shaped regurgitant orifice creating a crescent shaped flow convergence. Direct Measurement of Proximal Isovelocity Surface Area by Single-Beat Three-Dimensional Color Doppler Echocardiography in Mitral Regurgitation: A Validation StudyJournal of the American Society of EchocardiographyVol. 25Issue 8PreviewThe two-dimensional (2D) proximal isovelocity surface area (PISA) method has some technical limitations, mainly the geometric assumptions of PISA shape required to calculate effective regurgitant orifice area (EROA). Recently developed single-beat, real-time three-dimensional (3D) color Doppler imaging allows direct measurement of PISA without geometric assumptions. The aim of this study was to validate this novel method in patients with chronic mitral regurgitation (MR). Full-Text PDF
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