Anatomy of discordant atrioventricular connections.

The term discordant atrioventricular connections refers to the situation in which the ventricles are connected inappropriately to the atrial chambers. In most instances, the connections of the great arteries are also abnormal, with the aorta and the pulmonary trunk arising from morphologically inappropriate ventricles. This combination results in the presence of so-called congenitally corrected transposition. Double-outlet right ventricle is occasionally present, while concordant ventriculoarterial connections may be seen rarely. Most such hearts have a range of additional abnormalities, including ventricular septal defects; outflow tract obstruction, usually of the morphologically left ventricle; anomalies of the morphologically tricuspid valve; and a highly abnormal location of the specialized atrioventricular conduction axis. Some examples exhibit bizarre abnormalities of ventricular relationships and topology, including criss-cross atrioventricular connections and superoinferior ventricular relations. In describing the anatomy of these malformations, it is important to use a step-by-step segmental approach to the documentation of the connections and associated defects in each case and to avoid potentially confusing shorthand terms.