d-Transposition of the Great Arteries (d-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, or transposed. This condition is called "d-Transposition" to differentiate it from "l-Transposition," a different and less serious condition.

Characteristics of d-TGA

  • Reversed Positions of the Aorta and Pulmonary Artery: In a normal heart, the aorta arises from the left ventricle and carries oxygen-rich blood to the body, while the pulmonary artery arises from the right ventricle and carries oxygen-poor blood to the lungs. In d-TGA, these positions are reversed.

  • Separate Circulatory Systems: This results in two parallel but separate circulatory systems - one that circulates oxygen-poor blood between the body and the right side of the heart, and another that circulates oxygen-rich blood between the lungs and the left side of the heart.

  • Associated Defects: Many babies with d-TGA also have a ventricular septal defect (VSD), an atrial septal defect (ASD), or a patent ductus arteriosus (PDA), which can allow some mixing of oxygen-rich and oxygen-poor blood.

Symptoms

Symptoms typically appear very soon after birth and include:

  • Cyanosis (a bluish tint to the skin, lips, and fingernails)

  • Difficulty breathing

  • Poor feeding

  • Lethargy

Diagnosis

d-TGA is often diagnosed shortly after birth through:

  • Echocardiogram: An ultrasound of the heart that shows the structure of the heart and blood flow.

  • Chest X-ray: To view the size and shape of the heart and lungs.

  • Electrocardiogram (ECG): To measure the electrical activity of the heart.

  • Cardiac catheterization: In some cases, to provide detailed information about the heart's structure and function.

Treatment

Treatment for d-TGA is surgical and is typically required soon after birth:

  • Arterial Switch Operation: This is the most common surgery for d-TGA. The surgeon switches the aorta and pulmonary artery to their correct positions, reattaches the coronary arteries to the new aorta, and closes any associated septal defects.

  • Atrial Switch Operation (Senning or Mustard Procedures): These older procedures create a pathway for oxygen-poor blood to flow to the left ventricle and then to the lungs and for oxygen-rich blood to flow to the right ventricle and then to the body.

Long-term Outlook

With timely surgery, most infants with d-TGA can lead relatively normal lives, although they will require lifelong follow-up with a cardiologist. Potential long-term issues include problems with the heart's rhythm, function of the heart valves, and the condition of the coronary arteries. Regular medical check-ups are necessary to monitor these potential complications and manage overall heart health. Advances in surgical techniques have significantly improved the prognosis for children born with d-TGA.