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

Abstract

Background: 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.

Methods: 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.

Results: 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%.

Conclusions: 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.