Surgical implications of juxtaposition of the atrial appendages. A review of forty-nine autopsied hearts.

We studied 49 hearts with juxtaposition of the atrial appendages, concentrating on the associated malformations and features of operative importance. Left juxtaposition was found in 42 cases (86%) and right juxtaposition in seven cases (14%). In the group of hearts with right juxtaposition, a normal segmental arrangement was present in three cases, double inlet in two cases, and double-outlet right ventricle in the remaining two cases. Hearts with left juxtaposition had usual atrial arrangement with concordant atrioventricular connection, together with anomalous ventriculoarterial connection in 22 cases and univentricular atrioventricular connection in 19 cases. Only one specimen had a normal segmental arrangement. A partial form of left juxtaposition was present in 60% of the specimens. Hearts with left juxtaposition had a transverse orientation of the atrial septum, which was displaced posteriorly and inferiorly in the medial atrial wall, separated from the orifice of the juxtaposed appendage by a muscular band. A small right atrial chamber was noted in hearts with anomalous ventriculoarterial connection, creating the potential for anatomic difficulties during operation conducted within the atria. In two thirds of the cases with classic tricuspid atresia, the size of the orifice of the juxtaposed appendage was larger than the atrial septal defect, and an anastomosis of the appendage with the pulmonary trunk was morphologically feasible.