[Transposition of the great arteries with horizontal interventricular septum (author's transl)].

Transposition of the great arteries with horizontal interventricular septum is characterized by a superior-inferior relationship of the ventricular chambers in the presence of ventriculo-arterial discordance. Embryologically this very peculiar anatomy can be explained by a rotation of the bulboventricular loop around a sagittal axis. A typical case is reported. The most important anatomical features are described and the embryologic mechanisms leading to this ventricular arrangement are discussed. The significance of this deformity to nomenclature of congenital heart disease is emphasized.