D-transposition of the great arteries (d-TGA)

In D-transposition of the great arteries, the aorta arises from the right ventricle and the pulmonary artery from the left (so-called ventriculo-arterial discordance). As a result, the systemic and pulmonary circulations do not follow in succession, but are parallel. The infants are capable of life only if there is an additional short circuit at atrial or ventricular level in the form of an ASD or VSD.

The incidence of TGA is reported as 3 to 7 % of all heart defects. Untreated, the average life expectancy is about 2 months.

The condition can be classified as follows, depending on the associated malformations:

• Transposition of the great vessels without VSD (“simple TGA“ 36 %).
• Transposition of the great vessels with a large VSD (49 %)
• Transposition of the great vessels with left ventricular outflow tract obstruction (LVOTO) with or without VSD (26 %)

  In many infants, the blood mixing in the heart must be improved by an emergency procedure. Two methods are available today:

  • In Rashkind atrioseptostomy, a wide tear is made in the atrial septum by a balloon catheter (Rashkind and Miller 1966).
  • The Blalock and Hanlon atrioseptostomy consists of surgical creation of an atrial septal defect (Blalock and Hanlon 1950).

    According to current knowledge, anatomical correction in the form of an arterial switch operation offers the best long-term prognosis. The large vessels and the coronary arteries are switched and so normal haemodynamics are created. With this method, technical difficulties can arise due to coronary artery anomalies.

    The arterial switch operation should be performed within the first two weeks of life after the diagnosis is made as the left ventricle subsequently becomes hypotrophic and is not able to meet the demands as systemic ventricle after the switch.