1. Home
  2. Library: Fetal CHD Image Library
  3. Lesion: Transposition of the Great Arteries

Transposition of the Great Arteries (D-TGA)

Josh Kailin, MD

 

Transposition of the great arteries (D-TGA) is a conotruncal abnormality characterized by discordant ventricular-arterial connections. In D-TGA, the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle. The aorta is anterior and rightward. The pulmonary and aortic circulations are in parallel instead of in series.

 

D-TGA occurs in ~31.5 in 100,000 live births

D-TGA is the second most common cyanotic heart disease following tetralogy of Fallot

Male predominance (2:1 male to female ratio)

 

Genetic Considerations

  • Rarely hereditary, however, infants of diabetic mothers are at increased risk.

 

Associated Findings

  • Ventricular septum: Intact (60%) vs ventricular septal defect (VSD) (40%).
  • Pulmonary stenosis (30%).
  • TGA/VSD can be associated with overriding or straddling AV valves
  • Hypoplastic aortic arch/coarctation of aorta.
  • Outflow tract obstruction (most commonly left ventricular outflow tract)
  •  Coronary artery abnormalities (defined postnatally)

 

Fetal Imaging Pearls

  • D-TGA can be missed as the apical 4 chamber view often appears normal with symmetric ventricles and normal appearing AV valves
  • On outflow tract sweeps, the great arteries DO NOT CROSS, rather they are in parallel with the aorta anterior and rightward to the pulmonary artery
  • Five chamber view demonstrates the pulmonary artery (early bifurcating vessel into two branches, right and left pulmonary arteries) arising from the posterior left ventricle
  • On longitudinal views, the aortic arch is seen arising from the anterior right ventricle and giving rise to the head and neck vessels
  • Establish origin and position of the great arteries from multiple views with good full sweeps to assess great artery relationship to the ventricles
  • Three-vessel trachea view in most cases will demonstrate a single large vessel (aorta) with the superior vena cava rightward
  • Short axis view of great arteries demonstrates aorta and pulmonary artery as circular structures next to one another
  • Assess PFO size and shunting pattern (aneurysmal atrial septum with to-fro motion and bidirectional shunting may indicate a restrictive atrial communication)
  • Assess PDA and direction of shunting (bidirectional or left-to-right shunting at PDA may indicate restrictive atrial communication)
  • Multiple sweeps of the ventricular septum to assess for VSDs
  • Assess right and left ventricular outflow tracts for malalignment/stenosis
  • Should there be a sizable VSD, assess for LVOT (subpulmonary) stenosis and pulmonary stenosis which are known associations (most often a perimembranous VSD)
  • Assess pulmonary and aortic valve size and function
  • Assess aortic arch dimensions and for evidence of hypoplasia/ coarctation
  • Assess ventricular size and function

 

Fetal Surveillance

  • Assess atrial communication, ductal shunting and outflow tracts, valvar regurgitation, aortic arch if concern for hypoplasia/coarctation.  If VSD, assess size of VSD and outflow tracts and pulmonary/aortic valves for evidence of hypoplasia/stenosis

 

Prostaglandins (PGE)  

  • Variable.  
  • Depends on whether concerns for coarctation, pulmonary stenosis or restrictive atrial septum.  PGE can assist in mixing postnatally so may be started until postnatal anatomy (atrial communication, aortic arch assessment) can be fully defined

 

Cath Intervention

  • If there are concerns for a restrictive atrial communication, arrangements with the interventional cath team are critical
  • Restrictive atrial septum may cause cyanosis and hemodynamic instability postnatally
  • Urgent balloon atrial septostomy may be required to aid in mixing 

 

 

References:
Moodie. 2014. Clinical management of congenital heart disease from infancy to adulthood.
Cohen. 2016. Multimodality Imaging Guidelines of Patients with Transposition of the Great Arteries: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance and the Society of Cardiovascular Computed Tomography. J Am Soc Echocardiogr. 2016 Jul;29(7):571-621.
Abuhamad A, Chaoui R. A Practical Guide to Fetal Echocardiography: Normal and Abnormal Hearts. 2nd Edition. 2009.
Views