Transposition of great arteries (TGA)
Transposition of the great arteries (TGA) is the most common cyanotic congenital heart lesion presenting in the neonate.
The hallmark of TGA is ventriculoarterial discordance, in which the aorta arises from the morphologic right ventricle and the pulmonary artery arises from the morphologic left ventricle.
In approximately 60% of the patients, the aorta is anterior and to the right of the pulmonary artery (dextro-TGA [d-TGA]). However in a subset of patients, the aorta may be anterior and to the left of the pulmonary artery (levo-TGA [l-TGA]).
The presence or absence of associated cardiac anomalies defines the clinical presentation and surgical management of a patient with TGA. The primary anatomic subtypes are
1. TGA with intact ventricular septum,
2. TGA with ventricular septal defect,
3. TGA with ventricular septal defect and left ventricular outflow tract obstruction, and
4. TGA with ventricular septal defect and pulmonary vascular obstructive disease.
Chest radiography :
1. Mild cardiomegaly.
2. Concave pulmonary artery segment.
3. Narrow mediastinum (Egg on string appearance)
4. Shunt vessels – depends on size of shunt and degree of PS.
Treatment
Medical :
Initial treatment consists of maintaining ductal patency with continuous IV prostaglandin E1 infusion to promote pulmonary blood flow, increase left atrial pressure, and promote left-to-right intercirculatory mixing at the atrial level.
Surgical:
TGA with intact ventricular septum: The ideal operation is an arterial switch procedure. It represents an anatomic repair and establishes ventriculoarterial concordance.
TGA with ventricular septal defect : The preferred operation is an arterial switch procedure with ventricular septal defect closure. If the ventricular septal defect is large and nonrestrictive and coronary artery anatomy makes an arterial switch operation inadvisable, a Rastelli-type intracardiac repair may be feasible.