Quantitative assessment of chronic aortic regurgitation with 3-dimensionalechocardiographic reconstruction: Comparison with electromagnetic flowmeter measurements

Two-dimensional echocardiography and color Doppler are useful in the qualit ative assessment of aortic regurgitation. However, color Doppler planar met hods are not accurate in quantifying regurgitant flow, in part because of t he complex geometry of aortic regurgitant flow events. Three-dimensional ec hocardiographic reconstruction is a new technique that provides dynamic 3-d imensional images of intracardiac color flow lets. We sought to determine w hether the measurement of aortic regurgitant jet volume by 3-dimensional ec hocardiography correlated with the true regurgitant volume, measured by ele ctromagnetic flowmeter in vivo, to accurately reflect the severity of aorti c regurgitation. We performed volume-rendered 3-dimensional echocardiograph y in 6 sheep with surgically induced chronic eccentric aortic regurgitation . We obtained a total of 22 aortic regurgitation states by altering loading conditions. Instantaneous regurgitant flow rates were obtained by aortic a nd pulmonary electromagnetic flowmeters. The maximum aortic regurgitant jet volume by 3-dimensional echocardiography and the maximum jet area by 2-dim ensional echocardiography were measured and compared with electromagnetic f lowmeter data. By electromagnetic flowmeter, aortic regurgitant flow rate v aried from 0.14 to 3.1 L/min (mean 1.25 +/- 0.78); aortic regurgitant strok e volume varied from 1 to 34 mL/beat (mean 12 +/- 8), and regurgitant fract ion varied from 3% to 42% (mean 25% +/- 12%). The maximum jet volume by S-d imensional echocardiography correlated very well with the aortic regurgitan t stroke volume (r = 0.92; P <.0001), with the mean regurgitant flow rate ( r = 0.87; P <.0001), and with the regurgitant fraction (r = 0.87; P <.0001) derived from electromagnetic flowmeter. Both intraobserver and interobserv er variability on the measurement of the jet volume by 3-dimensional echoca rdiography were excellent (r = 0.98; P<.0001 and r = 0.90; P<.001, respecti vely). The maximum jet area by 2-dimensional echocardiography did not corre late with the aortic regurgitant stroke volume (r = 0.41; P = not significa nt) and related poorly with the regurgitant fraction (r = 0.52; P <.05) by electromagnetic flowmeter. Dynamic 3-dimensional echocardiography can allow better determination of the geometry of the aortic regurgitant jet and may assist of quantifying the severity of aortic regurgitation.