[Cardiac surgery for the patients with hyperthyroidism].

Since open heart surgery may cause thyrotoxic crisis during the perioperative period in patients with hyperthyroidism, close monitoring and control are needed. We performed open heart surgery in 2 patients with hyperthyroidism, and good results were obtained. A 71-year-old patient with mitral valve insufficiency underwent mitral valve repair by replacement of chordae tendineae with polytetrafluoroethylene sutures and annuloplasty with a Duran's Ring. The other 20-year-old patient with aortic valve insufficiency underwent aortic valve replacement with an SJM valve. In the two patients, cardiopulmonary bypass for a prolonged period was required during surgery. However, thyrotoxic crisis could be prevented by controlling thyroid function by preoperative treatment with anti-thyroid agents, concurrent medication with Lugol's iodine solution immediately before surgery and re-administration of anti-thyroid agents early after surgery.