Chapter 3.26 Double discordance

Abstract

In this fascinating cardiac malformation, the morphologically left atrium (=pulmonary venous atrium) is connected via a tricuspid valve with the morphologically right ventricle, from which originates the aorta, while the morphologically right atrium (= systemic venous atrium) is connected via a mitral valve with the morphologically left ventricle, from which originates the pulmonary artery. Therefore two discordant connections, atrioventricular and ventriculoarterial (= double discordance), occur in sequence in each side of the heart. The classical definition of ``congenitally corrected transposition of the great arteries'' derived from the observation that the effects of transposition of the great arteries are ``corrected'' by the congenital inversion of the two ventricles, with the two circulatory pathways ``physiologically'' in series, despite the anatomic derangements.