Definition

  • Deficiency of aortopulmonary septum leading to a defect between ascending aorta and MPA.

Incidence

  • More in males.
  • No tendency to close spontaneously.

Embryology

  • Defect of aorto-pulmonary septum or
  • Malalignment of aorto-pulmonary septum and truncal septum

Anatomy

  • Between left side of ascending aorta and right side of MPA
  • Inferior end is 1 to 2 cm above coronary ostia
  • Single oval defect
  • Ventricular septum is intact
  • Isolated in 50%. Commonest association is PDA. Less common are aortic arch anomalies and anomalous origin of coronaries.

Classification

  • Mori’s classification
    • Type I- Midway between semilunar valves and pulmonary bifurcation
    • Type II- Distal defect with no posterior border and RPA originating from aorta
    • Type III- Combination of above two types
  • Kutsche and Van Mierop classification
    • Circular midway defect
    • Helical midway defect
    • Large defect with no posterior border

Hemodynamics

  • Volume overload of left sided chambers and pressure overload of right sided chambers
  • Early HF
  • Those who survive HF develop PVOD in infancy itself

Clinical features

  • LV cardiomegaly with left parasternal heave
  • Narrow split S2
  • Systolic murmur at left upper parasternal border

ECG

  • BVH with LAE

Chest X-ray

  • LV cardiomegaly with increased pulmonary vasculature
  • LAE
  • Aortic knuckle is not prominent

Echocardiography

  • Defect seen with T sign
  • Two semilunar valves excludes truncus arteriosus
  • LA and LV are dilated
  • Downward flow through right side of MPA
  • Continuous flow in pulmonary arteries
  • Diastolic flow reversal in both aortic arch and descending aorta (PDA- only in descending aorta)
  • No VSD and no right aortic arch (both these points differentiate from truncus arteriosus; also presence of two semilunar valves)

Cath study

  • Catheter passes from RV to MPA to ascending aorta

Management

  • Closure before 3 months of age.