Left Bronchial Compression by the Left Pulmonary Artery in a Patient with a Large Aortopulmonary Window

IMAGES IN MEDICINE A 3-month-old male child with breathing difficulty was investigated for suspected congenital cardiac disease. On echocardiography, the patient was found to have a small subaortic ventricular septal defect (VSD), a large aortopulmonary window, and normal biventricular function. The main pulmonary artery and its branches were confluent; the right pulmonary artery measured 3 mm, and the left pulmonary artery measured 6 mm. Computed tomography (CT) angiography examination demonstrated the right aortic arch in association with a large type II aortopulmonary window [Figure 1a]. The main pulmonary artery was dilated, and the right pulmonary artery was relatively small. The left pulmonary artery appeared dilated and had a longer course to the left hilum. While traversing anterior to the left main bronchus, it showed compression of the left bronchial lumen [Figure 1b and d]. The left lung was hyperlucent and appeared mildly hyperinflated. Compared with the right lung, the left lung showed fewer pulmonary arterial markings [Figure 1c]. The patient was offered surgical correction and is awaiting surgery.Figure 1: Axial contrast-enhanced computed tomography (CT) image (a) demonstrates right aortic arch and a large type II aortopulmonary window (star). Additional axial image (b) just below the carina shows compression of the left bronchus by the left pulmonary artery (open arrow). The bronchus appeared compressed between the left pulmonary artery and the body of the adjacent vertebra. Coronal reformatted CT (c) demonstrates a hyperlucent left lung showing relatively smaller pulmonary arterial divisions (white arrow). Volume rendered 3-D image of the airway (d) demonstrates complete occlusion of the left proximal bronchus, just beyond the carina (open arrow)Compression of the left bronchus by the main pulmonary artery, by an aneurysm of the pulmonary artery, or by a large patent ductus arteriosus is well documented in congenital heart disease.[1,2] Compression of the bronchus by the main pulmonary artery or the left pulmonary artery is relatively rare.[1] The mechanism of compression in our case appears to be due to trapping of the bronchus between the dilated artery and the adjacent vertebral column. Compression can be complete, leading to lung collapse, or intermittent, leading to air trapping. The extent of bronchial compression and secondary changes in the lung adversely affect intraoperative anesthetic management, postoperative patient care, and overall prognosis. Our case presents a very rare instance of the left bronchial compression by the left pulmonary artery in the complex heart disease consisting of VSD, right aortic arch, and the aortopulmonary window. Although the 3-D volume-rendered CT images show complete bronchial occlusion, the hyperlucent left lung suggests either intermittent or dynamic bronchial compression. Furthermore, bronchomalacia may be associated. Author contributions VB: Concept, data preparation, final approval. KG: data collection, draft preparation, Literature search. SS: Clinical input, initial drafting. Data availability statement All data generated during this study are included in this published article. For any further data requests, readers may contact the corresponding author. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his/her consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.