Quantification of mitral regurgitation by colour flow Doppler imaging--value of the 'proximal isovelocity surface area' method.

In this study 97 patients with mitral regurgitation (age 62 +/- 11 years, 55 men, 42 women) quantified by angiography were studied using colour flow Doppler imaging of isovelocity surface areas in the flow convergence region proximal to the regurgitant orifice. The radii of the proximal isovelocity surface areas for the flow velocities of 28 and 41 cm/s were measured. A flow convergence region was imaged in 100% (96%) of the patients with Grade I/II or more and in 92% (64%) of the patients with Grade I mitral regurgitation for a flow velocity of 28 (41) cm/s. The radii of the proximal isovelocity surface areas correlated significantly with the angiographic grade in patients with sinus rhythm as well as atrial fibrillation. A correct differentiation of Grade I to II from Grade III to IV mitral regurgitation was provided in more than 90% of all patients for both flow velocities investigated. Assuming hemispheric proximal isovelocity surface areas, in 11 patients the regurgitant volumes from echocardiography (range: 2.6-241 (0.9-198) ml for a flow velocity = 28 (41) cm/s) correlated with, but considerably overestimated the values from cardiac catheterization (range: 1.4-72.5 ml) with r = 0.79 (0.82) (P < 0.01) and SEE = 57.9 (42.4) ml for a flow velocity of 28 (41) cm/s. It was concluded that colour flow Doppler imaging of the flow convergence region enables the diagnosis of mitral regurgitation and the differentiation between Grade I to II and Grade III to IV mitral regurgitation, but may be of little value in estimating the regurgitant volume, assuming a hemispheric symmetry of the proximal flow convergence region.