The curvilinear relationship between aortic regurgitant volumes and color flow jets. Intraoperative two-dimensional Doppler and electromagnetic flowmeter correlation.

Abstract

The potential usefulness of two-dimensional Doppler to quantitate valvular regurgitation depends on the relationship between the dimensions of the velocity maps and the regurgitant volumes. We previously found a significant linear regression between aortic regurgitant fraction and jet area, but because of a shallow slope, postulated an exponential or curvilinear relationship. A retrospective analysis of intraoperative electromagnetic flowmeter measurements of aortic flow and epicardial color flow maps of regurgitant jets gave us a more direct examination of the relationship over a wider range of lower flows. Regurgitant volume was calculated from reverse aortic flow and was compared to jet length, area (by planimetry) and volume (from Simpson's rule). Both linear and curvilinear regressions were determined. Correlation coefficients were similar but consistently closer to unity with the exponential equations, and data points were more closely distributed along a curved rather than a straight line. Length regressions were flatter and the volume regressions were steeper than the slopes of the area equations. Thus, the relationship of the gradual slope of the color flow jet area to the regurgitant volume is geometrically determined and limits quantitative application.