Agenesis of the left pulmonary artery accompanied by right aortic arch anomaly: CT angiography findings of a case

Abstract

Unilateral absence of the pulmonary artery is a rare congenital anomaly that is encountered at a rate of 1/200,000. 1,2 Pulmonary artery agenesis can occur on either side, frequently on the right side, and usually co-exists with cardiac anomalies such as tetralogy of Fallot and septal defects. 3 This condition is frequently diagnosed in the neonatal period or in early childhood in patients suffering from shortness of breath, coughing, and frequent pulmonary infections. A 21-year-old male patient without significant medical history had been suffering from shortness of breath and mild thoracic pain for 2 months. The patient was evaluated by conventional radiography and computed tomography (CT) angiography of the chest. Postero-anterior chest radiography demonstrated decreased volume and radiolucency of the left hemithorax, the superiorly located left hemidiaphragm, the deviation of the mediastinal structures to the left, and an abnormal convex right mediastinal contour (black arrow), absence of the aortic contour on the left side (white arrow) and deviation of the trachea (*) to the left, consistent with a right-sided aortic arch (Panel A). To clearly demonstrate the lung parenchyma and thoracic vascular structures, a thorax CT angiography examination was performed (Panels B1-B4). On CT angiography images, the right aortic arch (AA) anomaly and a mirror-image branching pattern of the aortic arch were observed. First, a leftsided brachiocephalic artery (large white arrow), then a right-sided common carotid artery (narrow black arrow), and finally a right-sided subclavian artery (narrow white arrow) were arising from the aortic arch. While the main pulmonary trunk (PA), right pulmonary artery (large black arrow) and vascular distribution of the right lung were normal, the left pulmonary artery was absent. Enlarged bronchial and intercostal arteries (white arrowheads) originating from the descending aorta and collateral vascular structures (black arrowheads) originating from the left costocervical trunk were supplying the left lung. The bronchial branching pattern and the pulmonary venous structures (PV) of both lungs were normal. Echocardiography showed no associated cardiac pathology. In our patient, there was no history of recurrent pulmonary infection or associated cardiac anomaly, and pulmonary artery pressure at rest was measured as 21 mmHg, which is within normal limits. Routine follow-up every 6 months for possible complications such as pulmonary hypertension was recommended.