324 Unilateral pulmonary artery agenesis with controlateral embolism: a double vascular trouble

Methods and results A 60-year-old male patient underwent coronary angiography (CA) for a non-ST segment elevation myocardial infarction (NSTEMI). CA revealed significant multivessel disease. Both internal mammary arteries (AMI) were patent, with right IMA markedly larger than the left IMA. The exam revealed also an abnormal branch arising from the proximal right coronary artery extending backwards, likely to the right lung. Pre-operative chest radiograph demonstrated asymmetry of the two hemithoraces with slight elevation of the right hemidiaphragm, small ipsilateral lung, and mediastinal shift towards the right. The patient underwent urgent CABG surgery. Myocardial revascularization was successfully performed using both AMI and one saphenous vein segment. The postoperative course was complicated by respiratory failure requiring prolonged mechanical ventilation. A chest computed tomography angiography was performed, revealing complete absence of the right pulmonary artery and a left lower lobe segmental pulmonary embolism. Furthermore, blood in the hypoplastic right lung was supplied by multiple collaterals arising from RCA and right IMA. Intravenous heparin was started with clinical improvement. Two weeks later, a lung scintigraphy was performed, ruling out perfusion defects. The patient was discharged home on oral anticoagulation with warfarin. Conclusions Unilateral pulmonary artery agenesis (UPAA) is an uncommon congenital anomaly of the great vessels. Despite the absence of the pulmonary artery, blood supply of ipsilateral lung is provided by systemic collaterals originating from bronchial, intercostal, internal mammary, and sub-diaphragmatic arteries. More rarely, these collaterals may arise from the coronary arteries with different implications, ranging from asymptomatic condition to myocardial ischaemia and infarction. In our case, the condition was previously asymptomatic. The occurrence of pulmonary embolism contributed to worsen the ventilation–perfusion mismatch, explaining the respiratory failure during the postoperative period.