Transposition of the great arteries with posterior aorta and subaortic conus: anatomical and surgical correlation.

Three hearts studied at autopsy with transposition of the great arteries and posterior aorta with isolated or predominantly subaortic conus are described. In all cases the aorta was posterior and to the right of the pulmonary trunk. In two cases it was significantly distant from the pulmonary trunk and in one it was very close. The caliber of the pulmonary trunk was larger than that of the aorta: greater than 2:1 in two cases and less than 2:1 in one case. A well developed subaortic conus was seen in all cases and a small subpulmonary conus in one case. In the other two cases, the pulmonary valve was in fibrous continuity with the mitral valve. In all cases the aortic valve was higher than the pulmonary valve, the relative heights above the ventricles being 25/20, 25/30 and 40/60 mm, respectively. The left coronary artery ran posteriorly and to the left of the pulmonary trunk in all the cases. The length of the main stem of the left coronary artery was 11, 11 and 30 mm, respectively. We discuss the significance of this type of transposition of the great arteries for techniques currently used for surgical correction.