Pathologic anatomy of corrected transposition of the great arteries: medical and surgical implications

Because the double-switch operation (atrial switch plus arterial switch) has recently become feasible in selected patients with congenitally physiologically corrected transposition of the great arteries, a detailed understanding of the pathologic anatomy is now mandatory for cardiologists, radiologists, and surgeons.

A detailed study of the pathologic anatomy, the clinical implications, and the surgical implications was undertaken on 33 postmortem cases with two ventricles. A companion study was also performed of 44 postmortem cases with functionally only one ventricle. Hence this was an investigation of 77 postmortem cases.

Three main anatomic types of corrected transposition of the great arteries (TGA) with two ventricles were found: (1) TGA with solitus atria (S), L-loop ventricles (L), and L-TGA (L), that is, TGA [S,L,L] in 31 cases (94%); (2) TGA with solitus atria (S), L-loop ventricles (L), and D-TGA (D), that is, TGA [S,L,D] in 1 case (3%); and (3) TGA with inverted atria (I), D-loop ventricles (D), and D-TGA (D), that is, TGA [I,D,D] in 1 case (3%). Associated malformations resulted in 13 anatomic subtypes. In classical corrected TGA [S,L,L] with two ventricles, anomalies of the left-sided systemic tricuspid valve were present in 97%, with malformations of the left-sided systemic right ventricle in 91%.

The findings in corrected TGA with two ventricles and in cases with single ventricle support the view that anatomic repair such as the double-switch procedure, or left-sided right ventricle bypass such as the modified Norwood procedure followed by the modified Fontan procedure, is indicated in selected patients.