Transposition of the Great Arteries (TGA)

Transposition of the great arteries, or TGA, is a congenital heart defect in which the aorta arises from the right ventricle and the pulmonary artery from the left ventricle, creating two separate, parallel circulations. The infant survives only while blood can mix between them, through the ductus arteriosus, the foramen ovale or an atrial septal defect, or a ventricular septal defect. The typical newborn is term and well grown but becomes deeply cyanotic within hours of birth, and the cyanosis does not improve with 100% oxygen. A murmur is often absent, so a quiet heart does not rule it out. Many cases are found before birth or by newborn pulse oximetry screening. A continuous IV infusion of alprostadil, a prostaglandin E1, keeps the ductus open; because it can cause apnea, the nurse monitors breathing and oxygen saturation continuously and keeps airway equipment at the bedside. Balloon atrial septostomy can improve mixing, and the arterial switch operation is the definitive repair. Afterward, watch the ECG for ischemia and report signs of low cardiac output.