Interventricular delay in severe aortic stenosis recognized by gated radionuclear blood pool scanning

Twenty-four patients referred for cardiac catheterization for suspected aortic stenosis were investigated by equilibrium gated blood pool study. From the time-activity curves, end systole for each ventricle was determined and the delay between the two was calculated. The patients were divided into three groups according to their calculated aortic valve area. The mean delay in a control group of 20 normal subjects was 6 +/- 13 msec (mean +/- standard deviation). In group I (aortic valve area greater than 0.75 cm2) the delay was 16 +/- 25 msec (p = NS compared to controls); in group II (aortic valve area 0.5 to 0.75 cm2) the delay was 28 +/- 27 msec (p less than 0.01); and in group III (aortic valve area less than 0.5 cm2) the delay was 60 +/- 28 msec (p less than 0.001). Ten patients were restudied after valve replacement; their mean delay decreased markedly from 48 +/- 19 to 5 +/- 26 msec (p less than 0.001). Thus, this method appears to identify patients with severe aortic stenosis and may therefore be a useful adjunct to the noninvasive assessment of this disorder both before and after surgery.