EVALUATING ISOVELOCITY SURFACE-AREA FLOW CONVERGENCE METHOD WITH FINITE-ELEMENT MODELING

Through numerical experimentation we investigated the isovelocity surf ace area flow convergence method used in estimating regurgitant valve flow rates. Recent advances in three-dimensional color Doppler flow im aging have created renewed interest in this method. Experimentation wa s based on the use of depth-averaged finite element models of the left heart. The heart models studied varied from ''synthetic'' representat ions to a model of a left heart traced from an actual echocardiographi c image of a patient with a prolapsed mitral valve. The isovelocity su rface area flow convergence method overestimated regurgitant flow rate s throughout the Nyquist limits considered with a critical Nyquist lim it in which this overestimation is minimized. The angle dependence of Doppler color flow imaging partially corrects for this overestimation. The isovelocity surface area flow convergence method is a viable alte rnative to methods currently in use. Through numerical experimentation , we have begun to shed light on the inaccuracies inherent in this flo w convergence method.