Congenitally corrected transposition of the great arteries is a rare cardiac defect characterized by the combination of atrioventricular (AV) discordance and ventriculo-arterial (VA) discordance. The morphologic left ventricle and mitral valve supply the pulmonary circulation and the morphologic right ventricle and tricuspid valve supply the systemic circulation. The anatomy is described as congenitally 'corrected' because the flow of blood is normal with the deoxygenated systemic venous blood being pumped to the lungs and the well oxygenated pulmonary venous blood being pumped to the body. More than 90% of patients have additional anatomical abnormalities. The most frequent are ventricular septal defects, left ventricular outflow tract obstruction, and abnormalities of the tricuspid valve.
