Cardiac MR imaging reveals L-type transposition of the great vessels and failing right heart.

L-type transposition of the great vessels is a rare congenital heart disease in which both the great arteries and the ventricular chambers are reversed. Because this condition preserves a physiologic circulatory pathway, it can be challenging to diagnose in infants with no concurrent cardiac abnormalities. Early detection is essential, however, because these patients will eventually experience severe complications, as the structural right ventricle is unable to function long-term in the systemic position. We report a rare case of L-type transposition of the great vessels in a 32-year-old male who presented in adulthood with tachycardia and palpitations. The initial echocardiogram was inconclusive. Further imaging (cardiac MRI & transesophageal echocardiogram) revealed the inverted anatomy due to the presence of key morphological features, such as the malposed great vessels along with the moderator band and prominent trabeculae within the right ventricle, which was functioning systemically.