Transposition of the great arteries

Transposition of the great arteries (TGA), also known as dextro-transposition of the great arteries (d-TGA), is a serious congenital heart defect in which the two main arteries leaving the heart are switched (transposed). The aorta, which normally carries oxygen-rich blood from the left ventricle to the body, instead arises from the right ventricle and carries oxygen-poor blood. The pulmonary artery, which normally carries oxygen-poor blood from the right ventricle to the lungs, instead arises from the left ventricle. This creates two parallel circuits rather than the normal series circulation, meaning oxygen-poor blood is recirculated through the body without passing through the lungs for oxygenation, while oxygen-rich blood recirculates through the lungs without being delivered to the body. Newborns with TGA typically present with severe cyanosis (bluish discoloration of the skin) shortly after birth, along with rapid breathing, poor feeding, and respiratory distress. Survival depends on the presence of some communication between the two circuits, such as a patent foramen ovale, atrial septal defect, ventricular septal defect, or patent ductus arteriosus, which allows some mixing of oxygenated and deoxygenated blood. Without intervention, TGA is fatal in the neonatal period. Immediate management often includes prostaglandin E1 infusion to maintain the patent ductus arteriosus and a balloon atrial septostomy (Rashkind procedure) to improve mixing of blood at the atrial level. The definitive treatment is the arterial switch operation (Jatene procedure), which is typically performed within the first two weeks of life and involves reconnecting the great arteries to their correct ventricles along with reimplantation of the coronary arteries. Long-term outcomes following the arterial switch operation are generally excellent, though lifelong cardiac follow-up is required to monitor for potential complications such as coronary artery stenosis, neoaortic valve regurgitation, or pulmonary artery stenosis. The etiology of TGA is considered multifactorial, with both genetic and environmental factors contributing, though the exact cause remains incompletely understood in most cases.

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