Echo doppler validation of aortic valve resistance in assessment of severity of aortic stenosis

Estimation of aortic valve area (AVA) in patients with aortic stenosis (AS) by catheterization (Gorlin) and by Echo Doppler (continuity equation) has limitations The purpose of the study was to demonstrate that aortic valve resistance (AVR) is a more stable parameter in assessment of AS severity. The results of catheterization and Doppler echocardiography performed within 2 weeks of each other, were compared in 33 patients with AS, 21 male and 12 female. The patients ages ranged from 24 to 93 years (mean (61±7). Mean gradient (mG), AVA and AVR were measured. AVR was estimated as HR.SEP.mG.1,333/CO dynes/cm/sec^-5 Heart rate (HR) and cardiac output (CO) were markedly different at the time of echo Doppler and catheterization procedures. The correlation between echo Doppler and catheterization for AVA was 0.68 which increased to r=0.77 when only 21 pts with left ventricular ejection fraction of 50% or greater were included. The correlation for mG was r=0.87 (P<0.01) and for AVR r=0.98 (P<0.001). Values below 200 dynes/cm/sec^-5 were observed when the AVA was greater than 1.2 cm². The highest AVR values, 594 and 796 respectively were obtained in two patients in whom aortic valve area by catheterization could not be obtained due to the difficulty in crossing the valve. Aortic valve resistance estimated by Echo Doppler appears to be a reliable parameter for assessment of severity of aortic stenosis.