Comment
Anomalous origin of branch pulmonary artery from aorta (AOPA) is an
extremely rare condition accounting for only 0.1% of all congenital
heart defects. (1) Aortopulmonary septum develops by fusion of right and
left conotruncal ridges. Severe mal-alignment of these conotruncal
ridges results in anomalous origin of the RPA from the ascending aorta.
AOPA can be isolated or it may be associated with other cardiac defects.
The most common associated lesion is patent ductus arteriosus, seen in
50% of cases. Rarely, it is associated with TOF, ventricular septal
defect (VSD), Aortopulmonary window ( APW), Interrupted aortic arch and
atrial septal defect. Anomalous origin of right pulmonary artery (AORPA)
is far more common than anomalous origin of left pulmonary artery
(AOLPA). (2) However, in tetralogy of Fallot AOLPA is far more common
than AORPA. Clinical features are those of increased pulmonary blood
flow and congestive heart failure. The cyanosis associated with
tetralogy of Fallot may not be apparent due to increased blood flow to
the ipsilateral lung. Differential lung vascularity on chest radiogram
may be suggestive of the diagnosis. The repair should be performed
immediately after diagnosis to prevent congestive heart failure and
ipsilateral pulmonary hypertension. Our patient had an added complexity
in the form of anomalous coronary crossing the pulmonary annulus. The
incidence of anomalous coronary artery or a large conal artery crossing
the RVOT is 10.2% based on a meta analysis of 28 studies. (3) The
combination of AOPA and ACA with TOF has not been previously reported in
the literature. ACA was circumvented by interposing a hand-sewn bovine
pericardial tube with a tri-leaflet valve constructed from PTFE
membrane. The integrity of the native pulmonary valve was maintained
allowing future growth as has been proposed in literature. (4) This was
demonstrated in our patient on echocardiogram examination. The native
pulmonary annulus has increased in diameter from 6 mm to 8 mm over a
period of 30 months. A promise of this growth potential combined with a
larger than required RV to PA conduit will delay or perhaps prevent
re-operations for the RVOT.