A 40-year-old male patient complaining of palpitations was referred to our hospital with severe pulmonary hypertension. (A) Echocardiography revealed an enlarged pulmonary trunk and the absence of the left branch as well as severe tricuspid regurgitation and pulmonary hypertension. The origin of the left branch was missing. To further explore the reason for the severe pulmonary hypertension, we performed computed tomography angiography. (B-D) Cinematic three-dimensional reconstruction from the computed tomography angiographic images demonstrated the anomalous origin of the left pulmonary artery from the ascending aorta in the setting of a right-side aortic arch and a large patent arterial duct (arrow). The patient refused surgical intervention for personal reasons. He was prescribed bosentan and was strictly followed because of the severe pulmonary hypertension. Ao: aorta; ALPA: anomalous left pulmonary artery; DAo: descending aorta; MPA: main pulmonary artery; RPA: right pulmonary artery.