A 29-year-old man with high fever and chest pain was admitted to our hospital. He had undergone aortic valve replacement 1 month before admission to our hospital. Since computed tomography revealed a pseudoaneurysm in the ascending aorta, he underwent an emergency operation. An occlusion catheter was inserted into the ascending aorta via the left femoral artery, in preparation for pseudoaneurysm rupture. Cardiopulmonary bypass was established with inflow via the right femoral artery and the right axillary artery, and with vacuum-assisted venous drainage via the right femoral vein. After core cooling, we performed resternotomy. The pseudoaneurysm ruptured while we were exfoliating the adhesion around the aorta. We inflated the occlusion catheter in the ascending aorta and controlled the bleeding. We continued core cooling and ventricular fibrillation occurred at 30°C. Subsequently, we induced circulatory arrest, and selective cerebral perfusion was initiated. We inflated the occlusion catheter in the descending aorta and initiated systemic circulation with inflow via the right femoral artery. The origin of the pseudoaneurysm was the region of cannulation in the previous operation. Therefore, we replaced the ascending aorta and performed omentopexy. In this case we reported the use of a strategy involving cardiopulmonary bypass for a pseudoaneurysm in the ascending aorta.