Fatal pseudoaneurysm of the subclavian artery secondary to infected modified Blalock–Taussig–Thomas shunt: a case report

Abstract Pseudoaneurysm is a rare but life-threatening complication of the modified Blalock–Taussig–Thomas shunt (mBTTS). We report a 3-year-old girl with pulmonary atresia and ventricular septal defect who underwent staged bilateral mBTTS and presented three months later with fever, acute respiratory distress, and worsening cyanosis. Initial findings suggested severe pneumonia, with right lower-lobe consolidation and abnormal mediastinal contour on chest radiography. Echocardiography and computed tomography angiography revealed a massive, thrombosed pseudoaneurysm of the right subclavian artery at the mBTTS anastomosis, complete thrombosis of the right pulmonary artery, right lung collapse, and concomitant pneumonia. Additional findings included left isomerism and a horseshoe kidney. Despite urgent broad-spectrum antibiotics and referral for emergency surgery, the child rapidly deteriorated and died before intervention. This case emphasizes the need for high clinical suspicion and early advanced imaging in post-mBTTS patients presenting with sepsis or cardiorespiratory compromise.