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To the Editor,
A 6-year-old cyanotic child with a diagnosis of ventricular septal
defect- pulmonary atresia underwent computed tomography angiography
(CTA) to look for the status of pulmonary arteries, aorto-pulmonary
collaterals and the coronaries. CTA showed a perimembranous ventricular
septal defect with pulmonary atresia. The pulmonary arteries were
confluent, with the presence of multiple major aortopulmonary collateral
arteries (MAPCAs). Three MAPCAs were seen supplying the right lung and
one was supplying the left lung. The MAPCAs supplying the right lung
showed aneurysmal dilatations along their course, with the largest
collateral measuring 14 mm in calibre, arising from the descending
thoracic aorta at D7 level. There was extrinsic compression of the
bronchus intermedius between the dilated right descending pulmonary
artery and one of the aneurysmally dilated MAPCAs (Fig. 1-2) .
Aortic arch was right-sided, with four-vessel arch branching pattern,
showing anomalous direct origin of right vertebral artery from the arch(Fig. 2) . The arch was dilated causing mild side-to-side
tracheal flattening. Bilateral lungs showed mosaic attenuation, with
presence of azygous fissure. Coronaries were normal with normal systemic
and pulmonary venous drainage.
When the pulmonary arterial tree is underdeveloped, such as in pulmonary
stenosis or atresia, aortopulmonary collaterals act as systemic to
pulmonary shunts and maintain blood supply to the lungs (1,2). MAPCAs
with calibre > 3mm are usually characterized by high
systemic pressure. Aneurysm formation and segmental pulmonary
hypertension are known complications of hypertensive MAPCAs (1). Airway
compression by MAPCAs is rare. Compression of central airways may
present with choking episodes and respiratory distress (3). Moreover,
airway compression can lead to bronchomalacia and patients may present
with massive hemoptysis due to associated bronchial erosion (4,5).
Variant arch anatomy is also associated with airway compression
particularly when there is complete vascular ring. Moreover the right
aortic arch can also compress the airway in cases with associated
bronchial aberrations, such as tracheal bronchus (3). CTA nicely
delineates the anatomy of aortopulmonary collaterals in addition to the
native pulmonary circulation which helps in devising optimal management
plan.