Right juxtaposition of the auricular appendages.

3 cases are described exhibiting the rare malformation of right juxtaposition of the auricular appendages. 1 case was encountered unexpectedly during surgical repair of an atrial septal defect and the patient survived. In this instance the segmental arrangement was solitus-concordant-normally connected arteries and the only associated defects in the heart were the atrial septal defect and a persistent left superior vena cava. In contrast, the other cases were discovered at autopsy and in both the juxtaposition accompanied severe additional anomalies. Common atrioventricular canal deformities were present in ambiguus 1-loop hearts and the ventriculo-arterial connections were double outlet right ventricle with d-malposition and normal connections with d-malposition respectively. Histological study in one of the hearts confirmed the presence of 1-bulboventricular looping, and showed an unusual arrangement of conducting tissues. Two atrioventricular nodes were present, and each communicated via separate atrioventricular bundles with the ventricular conducting tissues. The cases are compared with other reported examples of right juxtaposition, and it is indicated that whereas right juxtaposition is frequently an isolated finding this is rarely the case in the more common left juxtaposition.