Pathogenesis and Surgical Treatment of Congenitally Corrected Transposition of the Great Arteries (ccTGA): Part III

Abstract

Congenitally corrected transposition of the great arteries (ccTGA) is an infrequent and complex congenital malformation, which accounts for approximately 0.5% of all congenital heart defects. This defect is characterized by both atrioventricular and ventriculoarterial discordance, with the right atrium connected to the morphological left ventricle (LV), ejecting blood into the pulmonary artery, while the left atrium is connected to the morphological right ventricle (RV), ejecting blood into the aorta. Due to this double discordance, the blood flow is physiologically normal. Most patients have coexisting cardiac abnormalities that require further treatment. Untreated natural course is often associated with progressive failure of the systemic right ventricle (RV), tricuspid valve (TV) regurgitation, arrhythmia, and sudden cardiac death, which occurs in approximately 50% of patients below the age of 40. Some patients do not require surgical intervention, but most undergo physiological repair leaving the right ventricle in the systemic position, anatomical surgery which restores the left ventricle as the systemic ventricle, or univentricular palliation. Various types of anatomic repair have been proposed for the correction of double discordance. They combine an atrial switch (Senning or Mustard procedure) with either an arterial switch operation (ASO) as a double-switch operation or, in the cases of relevant left ventricular outflow tract obstruction (LVOTO) and ventricular septal defect (VSD), intra-ventricular rerouting by a Rastelli procedure. More recently implemented procedures, variations of aortic root translocations such as the Nikaidoh or the half-turned truncal switch/en bloc rotation, improve left ventricular outflow tract (LVOT) geometry and supposedly prevent the recurrence of LVOTO. Anatomic repair for congenitally corrected ccTGA has been shown to enable patients to survive into adulthood.

Keywords: congenitally corrected transposition; diagnosis; discordant atrioventricular connections; discordant ventriculoarterial connections; operation procedures.

Figure 1

Diagrams of the normal heart (A) and ccTGA (B). In the normal heart, the pulmonary artery arises from the right ventricle, and the aorta arises from the left ventricle (RA with LV, LA with RV). In ccTGA, the right atrium is connected to the morphological LV, which ejects blood into the pulmonary artery, whereas the left atrium is connected to the morphological RV, which ejects blood into the aorta. The ventricles are inverted. RA: right atrium; RV: right ventricle; PA: pulmonary artery; LA: left atrium; LV: left ventricle. This figure was modified and reproduced with permission from Goldmuntz et al. [9].

Figure 2

Disposition of cardiac conduction system in ccTGA. Ao indicates the aorta; AV, atrioventricular; cs, coronary sinus; LBB: left bundle branch; LV: left ventricle; PT: pulmonary trunk; RA: right atrium; RBB: right bundle branch; RV: right ventricle; VSD: ventricular septal defect. This figure was taken from the article of Baruteau et al. [19] distributed under the terms of the Creative Commons Attribution License (CC BY).

Figure 3

Indications for surgical intervention in ccTGA. CcTGA: congenitally corrected transposition of the great arteries; RV: right ventricle; PA: pulmonary artery. This figure was reproduced with permission from Kumar [29], under the terms of the Creative Commons Attribution License (CC BY).

Figure 4

Schematic representation of anatomic repair in the form of a double-switch operation by restoring flow in the normal arrangement. The figure shows the steps involved in the so-called double-switch procedure. Ao: aorta; IVC: inferior vena cava; SVC: superior vena cava; PV: pulmonary veins; PT: pulmonary trunk, mRV: morphologically right ventricle; mLV: morphologically left ventricle.

Figure 5

Algorithm for anatomical correction of ccTGA. ccTGA: congenitally corrected transposition of the great arteries; LVOTO: left ventricular outflow tract obstruction; VSD: ventricular septal defect. This figure was reproduced with permission from Kumar [29], under the terms of the Creative Commons Attribution License (CC BY).

Figure 6

Schematic representation of the Rastelli–Senning operation. The figure shows the final result after an atrial redirection procedure combined with intra-ventricular rerouting of the ventricular septal defect to the aorta, and the placement of a conduit from the morphologically right ventricle to the pulmonary arteries. Ao: aorta; IVC: inferior vena cava; SVC: superior vena cava; PV: pulmonary veins; 1: conduit from morphologically right ventricle to pulmonary arteries; 2: interventricular tunnel from morphologically left ventricle to aorta.

Figure 7

Schematic representation of the hemi-Mustard–Rastelli–Glenn operation. (A) Diagram of hemi-Mustard/bidirectional Glenn (BDG) operation with the Rastelli–atrial switch procedure in a dextrorotated heart. BDG: bidirectional Glenn shunt; IVC: inferior vena cava; LV: left ventricle; RV: right ventricle. (B) The “Hemi-Mustard” technique. A bidirectional Glenn shunt has been performed and the atrial septum has been excised. A circular patch of Goretex^® is used to baffle the IVC through to the tricuspid valve. The coronary sinus has been laid open to give extra volume to the pathway. Figure (A) was modified and adapted from Malhorta et al. [88].