Truncus arteriosus (Van Praagh type A4)

Case contributed by Vincent Tatco
Diagnosis certain



Patient Data

Age: Neonate
Gender: Female
  • The small ascending aorta and dilated main pulmonary artery share a common trunk overlying a ventricular septal defect.
  • There is interruption of the aortic arch between the left common carotid and left subclavian artery
  • The proximal descending aorta arises from the main pulmonary artery via a patent ductus arteriosus
  • Aberrant right subclavian artery distal to the left subclavian artery is demonstrated.

Case Discussion

Truncus arteriosus is an uncommon congenital cardiac abnormality that occurs due to the failure of conotruncal septation during development of the fetus. It is characterized by a single arterial trunk that originates from the heart and supplies the systemic, pulmonary, and coronary circulation 1.

The original and more popular classification of truncus arteriosus was devised by Collett and Edwards in 1949, which divides this anomaly into four types 2:

  • type I: Common pulmonary artery arising from truncus – 80%
  • type II: Right and left pulmonary artery arise separately from the posterior part of truncus
  • type III: Separate origins of the pulmonary arteries from the lateral aspect of the truncus
  • type IV: Neither pulmonary arterial branch arising from the common trunk (pseudotruncus), is now recognized to be a form of pulmonary atresia with VSD rather than truncus arteriosus

In 1965, Van Praagh modified the classification system which also includes four primary types 3:

  • type A1: Identical to the Type I of Collett and Edwards
  • type A2: Separate origins of the branch pulmonary arteries from the left and right lateral aspects of the common trunk
  • type A3: Origin of one branch pulmonary artery (usually the right) from the common trunk, with other lung supplied either by collaterals or a pulmonary artery arising from the aortic arch
  • type A4: Coexistence of an interrupted aortic arch

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