Transposition of Great Arteries

Abstract

TGA is the commonest complex congenital cyanotic cardiac anomaly occurring during the first week of life. It is characterized by the unusual anomaly of ventriculoarterial discordance, with the aorta (A) originating from the right ventricle (RV) and the pulmonary artery (PA) from the left ventricle (LV). In the common Dextro form (DTGA), A is abnormally located to the right, anterior, and inferior of PA. The anatomic configuration results in the lethal hemodynamic pattern of 2 independent and parallel running circulatory circuits, which mandates creating a conduit to ensure the mixing of oxygenated and deoxygenated blood for survival. In the rare Levo form (LTGA), the aorta is placed anterior and to the left of PA with ventricular inversion. TGA is well tolerated in the fetus and is challenging to diagnose by fetal echocardiography unless the outflow tracts are specifically visualized. Postnatally the typical findings of murmur and cyanosis vary according to the associated cardiac defects and the degree of intercirculatory mixing. The arterial switch operation (ASO), which involves establishing ventriculoarterial concordance, is the standard surgical repair of D-TGA and has replaced the atrial switch procedures due to its superior long-term outcomes. The Rastelli procedure is used for complex DTGA cases. DTGA has a 90% mortality rate in the first year of life if untreated, while over 95% survive for 5 to 25 years after surgery. Post-surgical course may be complicated and require surgical revisions. The long-term outcome is associated with normal or mild to moderate neurodevelopmental disabilities, depending upon the type, complexity, and course of the disease. Expert follow-up of the patients into adulthood is an integral part of the management of TGA for best outcomes.