Atrioventricular and ventriculoarterial discordance (congenitally corrected transposition of the great arteries): echocardiographic features, associations, and outcome in 34 fetuses.

OBJECTIVE: To identify fetal echocardiographic features, associations, and outcome of atrioventricular and ventriculoarterial discordance.

DESIGN: Retrospective analysis of videotape recordings of fetal echocardiograms and examination of departmental database and patient records to establish outcome.

SETTING: Tertiary centre for fetal cardiology.

PATIENTS: 34 consecutive fetuses with a prenatal diagnosis of double discordance seen between January 1993 and December 2003.

MAIN OUTCOME MEASURES: Echocardiographic features including reversed differential insertion, identification of the right ventricle through the moderator band, and the origin and orientation of the great arteries. All associated cardiac abnormalities and outcome.

RESULTS: Reversed differential insertion was identified in 26 fetuses. The right ventricle could be identified by the moderator band in 30 fetuses and was left sided in all but one. A parallel or abnormal orientation of the great arteries was seen in all fetuses. Only five of 34 cases were isolated from a cardiac viewpoint. There was a ventricular septal defect in 21, Ebstein's anomaly in 8, pulmonary stenosis in 12, coarctation of the aorta in 6, tricuspid atresia in 2, congenital heart block in 2 fetuses prenatally, and dextrocardia in 6. Nineteen babies survived; one baby died in the neonatal period and three in infancy. Eleven pregnancies were interrupted.

CONCLUSIONS: A left sided or posterior right ventricle, identified by reversed differential insertion or the moderator band, in association with abnormal orientation of the great arteries should alert a sonographer to the diagnosis of double discordance. Isolated cases are rare prenatally (14%) but the short term survival in our fetal series is good. Where pregnancy was continued, 19 of 23 babies (82%) remained alive.