Abstract
We present the case of a 61-year-old patient with a history of essential thrombocythemia (ET) who was diagnosed as having aortic valve stenosis and dilatation of his ascending aorta. His aortic valve and ascending aorta were replaced under hypothermic circulatory arrest (HCA). No clear guideline exists for preoperative, perioperative, and postoperative management of cardiac surgery using HCA for ET patients. After performing risk assessment, we prescribed preoperative aspirin therapy and postoperative care was planned as usual for cardiovascular surgery in our establishment. Unexpectedly, activated clotting time did not exceed 400 seconds, but the course of treatment was otherwise uneventful.