Juxtaposition of the atrial appendages.

Juxtaposition of the atrial appendages is a rare congenital cardiac malformation, with the appendages both located on the left or right side of the great arteries. It is usually associated with cyanotic congenital heart disease. The aim of this report is to illustrate the anatomical features of normal and juxtaposed atrial appendages, with a review of the associated anomalies. In the Anatomical Collection of Congenital Heart Disease of the University of Padua, consisting in 1,526 specimens, we found 17 (1.1%) cases of atrial appendages juxtaposition with left juxtaposition in 15 (88%) and right juxtaposition in 2 (12%). Complete form was present in 11 cases and partial form in 6. In left juxtaposition, the situs was solitus in all, and the most frequent anomalies were complete transposition of great arteries in 9 (60%) and tricuspid atresia in 5 (33%); anomalies of position of the heart in the thorax (dextro-mesocardia) were present in 46% of cases, hypoplastic right ventricle in 73%, abnormal relation of the great arteries and subaortic or bilateral infundibulum in all. In right atrial juxtaposition, the atrial situs was solitus with mitral and pulmonary atresia in one case and left isomerism with aortic atresia and double-inlet right ventricle in the other. In describing this malformation, we propose to maintain the use of a positional definition using the terms right and left juxtaposition to describe the presence of both the appendages on the right or on the left side of the great arteries, respectively. The use of a morphological definition should be added in cases of situs inversus or isomerism, with description of the morphology of the appendage located in the wrong position.