Congenitally corrected transposition of the great arteries (L-TGA).

In this complex cardiac anomaly, systemic venous inflow to the right atrium travels (anomalously) to the morphologic left ventricle, but then (again anomalously) to the pulmonary arteries. 

Concurrently, pulmonary venous inflow to the left atrium travels anomalously to the morphologic right ventricle which is indicated by the moderator band, but then (again anomalously) to the aorta.

Thus, is there is both atrioventricular and ventriculo-arterial discordance (double discordance) and as a result, blood flow occurs in the correct direction. Cyanosis does not ensue at birth, and this patient has reached adulthood without surgical correction. He did however require a pacemaker soon after this scan.

Associated cardiac anomalies are common - in this case there is an ASD, VSD and dextrocardia.