Aortic hypoplasia is a common observation in many congenital heart diseases  especially  acyanotic CHD. It is  important  to know the adequacy of systemic blood flow , in left-sided embryonic flow  defects like , co- arctation of aorta, interrupted aortic arch, shone’s complex etc .

The hypoplasia is thought to be due to two mechnaisms

1. Low flow state in utero( fetal heart) and the  resultant hypoplasia.

2.Ductal tissue migration into adjacent arch  which leads to  friendly arch  contraction !  when the  PDA gets closed

in the immediate new born period .

When do you suspect aortic hypoplasia ?

There is no strict definition available.But the Becker’s  data base provides a working rule.

Hypoplasia is diagnosed when ,

  • Isthmus is , < 40 % of  diameter of ascending aorta
  • Proximal  transverse arch  is ,  < 60 %  diameter of ascending aorta
  • Distal transverse aortic arch is , < 50%  of diameter of ascending aorta

Why ascending aorta is taken as reference ?

It is least likely to affected by the shrinking ductal tissue . Descending aorta can be a reference but it is at a  remote location and difficult to image .


Becker’s  CHD nomenclature and data base project . Annals of thoracic surgery  2000

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