Pulmonary valve eccentricity in d-transposition of the great arteries and implications for the arterial switch operation.

Neoaortic valve regurgitation is a known complication of the arterial switch operation for d-transposition. Its etiology and long-term effects are undetermined. Observations of pathologic specimens from 67 patients with d-transposition of the great arteries with or without ventricular septal defects demonstrated that the pulmonary valve leaflets had unequal cusp sizes leading to eccentric closure. The posterior cusp was usually the largest and was anatomically related to the membranous ventricular septum and the anterior leaflet of the mitral valve. The right cusp was usually the smallest. Differences in cusp sizes were unrelated to age at death, sex or presence of a ventricular septal defect. To determine if eccentricity could be clinically detected, the pulmonary valves in 24 sequential patients with d-transposition were studied echocardiographically and angiographically. Aortic valves were studied for comparison. All pulmonary valves demonstrated eccentric closure in the long-axis echo plane, posterior in 15 patients and anterior in 9. Only 1 aortic valve showed eccentricity. Angiographic findings correlated with echo findings. Sixteen patients underwent arterial switch operations; 3 died. Twelve had angiography at 1 year. Eleven had neoaortic valve regurgitation: 5 grade I, 4 grade II and 2 grade III.