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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.