The case describes the surgical treatment of a patient with a false aneurysm of the proximal anastomosis of the Sano shunt in a patient with hypoplastic left heart syndrome midterm after bidirectional cavo-pulmonary anastomosis. The diagnostic algorithm included a physical examination, echocardiography, and multispiral computed tomography. Surgical treatment included closure of the right ventricular defect and removal of blood clots from the cavity of the false aneurysm.