Normally aorta is posterior & to the right of the pulmonary Artery. In d-TGA aorta is anterior & to the right of the pulmonary artery (d means dextropositioned aorta, transposition indicates that it arises from the anterior right ventricle). The connections between the atria & ventricles are also normal (atrioventricular concordance). Aorta arises from the right ventricle and pulmonary artery from the left ventricle. So systemic & pulmonary circulation are two parallel circuits.

Survival in the immediate newborn period is by the foramen ovale & the ductus arteriosus which allow some mixture of oxygenated & deoxygenated blood.

Association: It is more common in infants of diabetic mothers. More common in males (3 : 1)


  1. d-TGA with intact ventricular septum (Simple or isolated TGA)

After birth there is closure of ductus artiriosus, so there is poor mixing of systemic & pulmonary blood via the patent foramen ovale. This causes hypoxia within 1st few days of life.

Clinical manifestation:

Moderate to severe hypoxia depending on the degree of atrial level shunting & whether the ductus is partially open or totally closed.

Cyanosis & tachypnea within 1st hours or days of life. It is a medical emergency.


  1. ECG – Usually normal with neonatal right sided dominant pattern.
  2. CXR   – Mild cardiomegaly

– Narrow mediastinum (classic “egg-shaped” heart)

– normal to increased pulmonary blood flow.

  1. Low arterial PO2 which does not arise after the patient breathes 100% oxygen (hyperoxia test).
  2. Echocardiography confirms the diagnosis.
  3. Cardiac catheterization – it is done for
  1. Patients requiring emergency balloon atrial septostomy.
  2. Higher oxygen saturation in LV & PA than in aorta.


  • Infusion of prostaglandin E1 to keep ductus arteriosus patent.
  • Rashkind balloon atrial septostomy- done in infants who remain hypoxia or acidotic despite prostaglandin infusion or in patients in which there is delay in surgery.
  1. d-TGA with ventricular septal defect
  • Large VSD- There is mixing of oxygenated & deoxygenated blood & clinical features of cardiac failure are present. There is enlargement of heart & presence of holosystolic murmur. Cyanosis is generally mild.


  1. CXR
  • Cardiomegaly
  • Narrow mediastinal waist
  • Increased pulmonary vascularity
  1. ECG
  • Prominent P waves
  • Isolated RVH or biventricular hypertrophy.
  1. Echocardiography – Confirms the diagnosis.
  2. Cardiac catheterization
  1. Rt & left ventriculography indicate presence of the arterial transposition./

Equal systolic pressure in 2 ventricles, aorta & pulmonary artery.


  1. Rashkind balloon atrial septostomy
  3. Arterial switch operation – can be performed after 1st 2 weeks of life because the VSD results in equal pressure in both ventricles and prevents regression of left ventricular muscle mass.
  4. In neonates with d-TGA & an intact ventricular septum, it is usually performed within the 1st 2 week of life. This is because as pulmonary vascular resistance declines after birth, pressure in the life ventricle also declines. This can result in a decrease in left ventricular mass over the 1st few weeks of life. So if arterial switch operation is done after left ventricular mass has decreased, left ventricle will be unable to generate pressure to pump blood to high pressure systemic circulation.

  5. L-transposition of the Great Arteries (Corrected Transposition).
  6. In L-TGA there is ventricular inversion, right atrium is connected to the left ventricle and the left atrium to the right ventricle. The great arteries are also transposed. Aorta is to the left of the pulmonary artery.

    The double inversion of the atrioventricular and ventriculoarterial relationships result in desaturated right atrial blood flowing to th lungs and oxygenated pulmonary venous blood flowing to the aorta. The circulation is thus physiologically “Corrected”.

    Total anomalous pulmonary venous return (TAPVR)

    It is associated with total mixing of systemic venous & pulmonary venous blood flow within the heart, before or at the level of the right atrium.

    This mixed right atrial blood either passes into the right ventricle & pulmonary artery or passes thorugh an ASD or paltent foramen ovale into the left atrium. The right atrium, RV & pulmonary artery are generally enlarged and LA & LV may be normal or small.


  7. Supracardiac (50%)
  8. Left SVC (40%)
  9. Rt SVC (10%)
  10. Cardiac (25%)
  11. Coronary sinus (20%)
  12. Right atrium (5%)
  13. Infracardiac (20%)
  14. Mixed (5%)