CONAL ANATOMY IN 119 PATIENTS WITH D-LOOP TRANSPOSITION OF THE GREAT-ARTERIES AND VENTRICULAR SEPTAL-DEFECT - AN ECHOCARDIOGRAPHIC AND PATHOLOGICAL-STUDY

Objectives. We sought to study the range of conal morphology in transp osition of the great arteries with ventricular septal defect and their embryologic and surgical implications. Background. Conal anatomy in t ransposition of the great arteries and ventricular septal defect is va riable and might affect surgical repair. Methods. Conal anatomy was ex plored using two-dimensional echocardiography in 119 patients with tra nsposition of the great arteries and a large ventricular septal defect who presented between 1984 and 1991. The influence of conal anatomy o n surgical technique was determined by review of the operative reports . Specimens of transposition of the great arteries with unusual conal anatomy were selected from the Cardiac Registry for comparison with th e echocardiograms. Results. One hundred five patients (88.2%) had suba ortic conus only with no subpulmonary conus (Group 1). Subarterial con us was present bilaterally in eight patients (6.7%) (Group 2). Four pa tients (3.4%) had only subpulmonary conus with no (or minimal) subaort ic conus (Group 3). Among these four patients, the aorta was posterior to the pulmonary artery in one patient, side by side relative to the pulmonary artery in two patients and slightly anterior in the fourth p atient. Subarterial conus was absent bilaterally in two patients (1.7% ) (Group 4); the aorta was slightly posterior in one and side by side with the pulmonary artery in the other. Conclusions. This variability of conal anatomy in transposition of the great arteries with ventricul ar septal defect implies four mechanisms by which transposition can oc cur. The conal anatomy appeared to affect surgical repair in Groups 1 and 2 insofar as it influenced ventricular outflow tract obstruction. In Groups 3 and 4, an arterial switch operation was performed in four of the six patients. The posterior location of the aorta obviated the need for the Lecompte maneuver in two of these four patients. In the r emaining two cases in Groups 3 and 4, the condition was repaired by di recting the left ventricular outflow across the ventricular septal def ect to the aorta using a patch, with or without placement of a conduit from the right ventricle to the pulmonary artery.