Doppler flow mapping and its comparison with the continuity equation method for quantifying aortic stenosis.

Abstract

The flow-mapping technique, which detects and planimeters the area of systolic flow at the site of the aortic orifice, was applied to 59 patients with a stenosed aortic valve, all of whom underwent cardiac catheterization. The success rate was 93%. The correlation coefficient between the values of valvular areas obtained by Doppler and those yielded by the Gorlin formula was r = 0.93 (SEE = 0.12 cm2). The continuity equation procedure, with the use of the velocity-time integrals, was applied sequentially to 20 of the above mentioned patients. The success rate was 85%. The valvular areas obtained in these patients by the Gorlin formula correlated well with those obtained with flow mapping (r = 0.90, SEE = 0.14, standard deviation of the difference = 0.13 cm2), as well as with those yielded by the continuity equation procedure (r = 0.86, SEE = 0.17 cm2, standard deviation of the difference = 0.16 cm2). Furthermore, the data from both ultrasonic methods were satisfactorily cross-correlated (r = 0.92, SEE = 0.12 cm2). It is noteworthy that the values of aortic valvular area obtained by Doppler were slightly larger than those found using either the continuity equation procedure or the Gorlin formula. The authors conclude that the flow-mapping technique represents a reliable method for quantifying stenotic aortic valvular area and correlates well with the continuity equation procedure. It is therefore suggested that, whenever possible, both techniques should be used sequentially as a valuable and practical cross-checking policy.