[Case of paroxysmal atrial fibrillation after general anesthesia caused by undiagnosed and untreated hyperthyroidism]

A 21-year-old man was scheduled to undergo posterior cruciate ligament reconstruction under arthroscopic control. The patient did not have a previous history of thyroid disease. Low blood cholesterol was revealed in the laboratory data. On arriving at the operating room, he showed sinus tachycardia of 130 beats x min(-1). Anesthesia was induced with remifentanil and propofol intravenously followed by sevoflurane inhalation, and maintained with remifentanil at a rate of 0.3 microg x kg(-1) x min(-1) and 2% sevoflurane. Heart rate was stable around 70-90 beats x min(-1) during the operation. After remifentanil and sevoflurane were discontinued following surgery, his heart rate increased and paroxysmal atrial fibrillation occurred. Although verapamil was administered intravenously, atrial fibrillation and tachycardia persisted. Further investigations revealed an elevated serum free thyroxin level and suppressed thyroid-stimulating hormone (TSH). Serum TSH receptor antibody concentration was elevated. Upon postoperative examination, goiter and the protuberance of the eyes were noticed. We conclude that he was suffering from Basedow disease. Although he had no subjective symptoms in the preoperative period, the possibility of hyperthyroidism should have been predicted from the laboratory data such as hypolipidemia and by conducting a careful medical examination. It seems that remifentanil suppresses sympathetic activity, and is useful for patients with hyperthyroidism.