Congenitally corrected transposition of the great arteries: an update.

Congenitally corrected transposition of the great arteries is a rare condition in which systemic venous blood returns to normally positioned atria. However, the atria are connected to the opposite ventricle, right atrium to left ventricle, left atrium to right ventricle; so-called atrioventricular discordance. In addition, the ventricles are inverted (right to left change in position) and are connected to the opposite great artery, left ventricle to pulmonary artery, right ventricle to aorta; thus, forming ventricular-arterial discordance. The aorta is anterior and to the left of the pulmonary artery, L-transposed. Atrioventricular discordance plus ventricular-arterial discordance results in normal blood flow (ie, congenitally corrected). The right ventricle with the tricuspid valve is the systemic ventricle. Common associated conditions are ventricular septal defects (VSDs), pulmonary stenosis, and congenital heart block. Major issues related to management revolve around the status of the systemic right ventricle, which can develop dysfunction with increasing age and tricuspid regurgitation, which can increase in severity with age and contribute to ventricular dysfunction. One emerging treatment is the double switch operation. In patients with no pulmonary obstruction, it is possible to switch the systemic and pulmonary venous return using an atrial baffle procedure followed by an arterial switch procedure. This results in the anatomical left ventricle now functioning as the systemic ventricle. In those patients with associated pulmonary obstruction and a VSD, another type of double switch can be performed in which the left ventricle is tunneled through the VSD to the aorta, the right ventricle is connected to the pulmonary artery with a homograft or other conduit, and the atrial baffle procedure is performed. The most difficult challenge is choosing the patient who is a candidate for the double-switch operation and the timing of that operation, or the timing of a more classical operation for associated defects.