Background. Imaging of the flow convergence region (FCR) proximal to a regurgitant orifice has been shown to provide a method for quantifying the regurgitant flow rate. According to the continuity principle, the FCR is constituted by concentric hemispheric isovelocity surfaces centered at the orifice. The flow rate is constant across all isovelocity surfaces and equals the flow rate through the orifice. For any isovelocity surface the flow rate (Q) is given by: Q=2 πr2 Vr, where 2πr2 is the area of the hemisphere and Vr is the velocity at the radial distance (r) from the orifice. Methods and Results. We studied 52 consecutive patients with mitral regurgitation (mean age, 49 years; age range, 21-66 years) verified by left ventricular angiography using color flow mapping. The FCR r was measured as the distance between the first aliasing limit - at a Nyquist limit obtained by zero-shifting the velocity cutoff to 38 cm/sec - and the regurgitant orifice. Seven patients without evidence of an FCR had only grade 1+ mitral regurgitation angiographically. There was a significant relation between the Doppler-derived maximal instantaneous regurgitant flow rate and the angiographie degree of mitral regurgitation in the other patients (rs=0.91, ps=0.75, p≤0.001). Conclusions. Color flow Doppler provides new velocity information about the proximal FCR in patients with mitral regurgitation. According to the continuity principle, the maximal instantaneous regurgitant flow rate, obtained with the FCR method, may provide a quantitative estimate of the severity of mitral regurgitation, which is relatively independent of technical factors.
|Number of pages||9|
|Publication status||Published - Oct 1991|
- Color Doppler flow mapping
- Continuity principle
- Mitral regurgitation
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine