Echocardiographic assessment of bicuspid aortic valves. Angiographic and pathological correlates

Aortic root echocardiograms were recorded from 89 patients whose aortic valves had also been adequately defined by selective angiography or viewed surgically or at autopsy. The eccentricity index (E.I.) of the aortic leaflets was measured at the onset of diastole and an E.I. of 1.3 or greater was taken as abnormal. Of 31 patients with isolated nonobstruced or mildly obstructed bicuspid aortic valves (7 viewed previously at valvotomy and 24 diagnosed radiologically) 23 (74%) had an abnormal E.I. Varying eccentricity occurred in some of these patients. Central leaflet echoes (E.I. of 1.0 to 1.25) were present in the other eight patients. All 14 patients with nonobstructed tricuspid aortic valves had central echoes. Additional multilayered diastolic echoes were found in patients with bicuspid aortic valves as well as in two patients with abnormal tricuspid aortic valves. The valves of 13 patients with aortic stenosis or incompetence were viewed surgically and the E.I. was abnormal in all patients with a bicuspid aortic valve in this group. Aortic leaflet echo findings were not diagnostically helpful in ten patients with tetralogy of Fallot, one of whom had a normal E.I. with a surgically confirmed bicuspid aortic valve. Of 21 patients with VSD only one had a bicuspid aortic valve but six had an abnormal E.I. This false positive sign was related to a high membranous VSD, sometimes with aortic valve prolapse. It is concluded that an E.I. of greater than or equal to 1.3 in the absence of an associated VSD is diagnostic of a bicuspid aortic valve and can be expected to be found in approximately three-quarters of subjects with this abnormality.