Juxtaposition of the atrial appendages; two cases of an unusual congenital cardiac deformity.

The two hearts here reported showed opposite manifestations of disordered bending of the primitive cardiac tube at an early stage of ontogeny. In both, the atrial appendages lay side by side instead of encircling the roots of the great vessels. In the first the two appendages lay to the right of both great vessels, a condition that does not appear to have been described. In the other both appendages lay to the left of both great vessels, a condition that has been reported eleven times, and with the present case forms a group with several other pathological features in common, including a decrease in the volume of the pulmonary circulation. Further similar cases are likely to be met as a result of the present interest in cardiac surgery, and among them may be some that can be helped by systemic-pulmonary shunt operations.