Transposition of the great arteries (TGA) is a serious congenital heart defect where the two main arteries leaving the heart—the aorta and the pulmonary artery—are switched in position. This abnormality disrupts the normal flow of blood, causing oxygen-poor blood to circulate through the body and oxygen-rich blood to loop back to the lungs, which can be life-threatening if untreated. Treating TGA involves a combination of medical management and surgical interventions designed to restore normal blood flow and oxygen delivery to the body.
Initially, when a newborn is diagnosed with TGA, the immediate goal is to ensure adequate mixing of oxygenated and deoxygenated blood to improve oxygen levels in the body. This is often achieved by maintaining or creating openings between the heart chambers or blood vessels. One common medical treatment is the administration of prostaglandin E1 (PGE1), a medication that keeps the ductus arteriosus—a fetal blood vessel connecting the pulmonary artery to the aorta—open. Keeping this vessel open allows some mixing of blood, which is critical for survival until surgery can be performed. The dose of PGE1 is carefully managed to balance sufficient blood flow without causing excessive pulmonary circulation, which can lead to complications.
If the natural openings between heart chambers, such as an atrial septal defect (ASD) or ventricular septal defect (VSD), are not adequate for mixing, a procedure called balloon atrial septostomy may be performed. This catheter-based intervention enlarges the opening between the atria (upper chambers of the heart), allowing better mixing of blood and improving oxygenation temporarily.
The definitive treatment for TGA is surgical correction, typically performed within the first few weeks of life. The most common and preferred surgical procedure is the arterial switch operation (ASO). This complex surgery involves switching the aorta and pulmonary artery back to their normal positions and reimplanting the coronary arteries to ensure the heart muscle receives proper blood supply. The ASO restores the normal circulation pattern, allowing oxygen-rich blood to flow to the body and oxygen-poor blood to the lungs. This operation has become the standard of care due to its excellent long-term outcomes.
In some cases, especially when TGA is accompanied by other heart defects like a ventricular septal defect or left ventricular outflow tract obstruction, surgical approaches may be modified. For example, the Rastelli procedure may be used, which involves closing the VSD and creating a conduit (a tube) to connect the right ventricle to the pulmonary artery. Another option is the atrial switch operation (Mustard or Senning procedure), which reroutes blood flow at the atrial level rather than switching the arteries. However, these procedures are less common today due to the superior results of the arterial switch.
Postoperative care is critical and involves monitoring heart function, managing complications, and supporting recovery. Some patients may require additional interventions such as catheter-based procedures to address residual or new issues like narrowed vessels or valve problems. Stents can be placed in narrowed blood vessels to improve blood flow, and balloon angioplasty can dilate constricted areas.
Long-term follow-up is essential because even after successful surgery, patients with TGA may face complications such as arrhythmias, coronary artery problems, or issues related to the heart valves. Regular cardiac evaluations help detect and manage these conditions early.
In rare and complex cases, heart transplantation might be considered, especially if surgical repair is not feasible or if severe complications develop. New surgical techniques continue to evolve, improving outcomes and reducing risks associated with these challenging congenital heart defects.
Overall, treatment for transposition of the great arteries is a carefully coordinated process involving initial medical stabilization, timely surgical correction, and lifelong cardiac care to ensure the best possible quality of life for affected individuals.
