Text
To the editor,
A 5-month-old child presented with history of recurrent chest infections
and feed intolerance. Two-dimensional trans-thoracic echocardiography
(TTE) showed a patent ductus arteriosus with left-to-right shunt and
mildly dilated pulmonary arteries. Computed tomography angiography
revealed separate origins of the segmental arteries of right upper lobe
from the mediastinal segment of the right pulmonary artery (RPA),
without truncus anterior. The origin of the apical segmental artery (A1)
was followed by that of the anterior segmental artery (A3) and posterior
segmental artery (A2)(Figure 1a, b). A non-azygous accessory
fissure was found in the right upper lobe separating the apical segment
from the anterior and posterior segments (figure 1c) . Findings
of TTE were confirmed with patent ductus arteriosus between the
descending thoracic aorta and main pulmonary trunk (Figure 2) ,
measuring around 6.5 mm in calibre. The aortic arch was left-sided with
normal branching pattern. However, the left vertebral artery showed
anomalous origin from the left common carotid artery (Figure
2) . Coronary arteries were normal with mosaic attenuation in bilateral
lungs.
Normally, the first branch of the RPA supplying the upper lobe, known as
the truncus anterior, arises just lateral to the thoracic spine on the
right side and then gives rise to the apical (A1) and anterior (A3)
segmental branches. The posterior segmental artery (A2) arises distal to
the truncus anterior(1). However, in the index case, there is separate
origin of all the segmental arteries of right upper lobe from the RPA,
consistent with the type-3 branching pattern which is a rare branching
pattern described in literature(2).To the best of our literature search,
we did not find any association of aberrant branching pattern of RPA
with patent ductus arteriosus, though an angiocardiographic study
highlighted the importance of RPA branching patterns in various
cardiovascular anomalies including situs inversus, tetralogy of Fallot,
aortopulmonary window, double outlet right ventricle, single ventricle
etc. (3). It is imperative to note that both the pulmonary arteries and
the ductus arteriosus are embryologically derived from the left sixth
aortic arch which might explain the coexistence of variant pulmonary
arterial anatomy and persistent ductus arteriosus, as seen in our
case(4). The left vertebral artery was seen arising from the left common
carotid artery, which is extremely uncommon and when there is anomalous
origin of the left vertebral artery, it usually arises directly from the
aortic arch(5). Accessory non-azygous fissure of the right upper lobe is
also very rare, and is mentioned in case reports. Although these
findings may be incidental, knowledge of such anatomic variations is
important, particularly in the background of congenital cardiovascular
diseases.