A 32-year-old obese male with bicuspid aortic valve and severely dilated ascending aorta (59.5 mm) underwent hemi-arch aortic replacement and valvuloplasty on cardiopulmonary bypass. Due to progressive respiratory failure, veno-venous extracorporeal membrane oxygenation (ECMO) was started on postoperative day 4. On postoperative day 15, ECMO flow fell and the patient was progressively desaturating. Chest X-ray was normal. Trans-Oesophageal echocardiography revealed a mobile thrombus in the right atrium (Fig.