[Intraoperative asystole in a patient with concealed sick sinus syndrome: a case report]

We report a patient with concealed sick sinus syndrome who developed intraoperative bradycardia and asystole. An 81-year-old man was scheduled to undergo total gastrectomy under general and epidural anesthesia. There was no history of syncope, and preoperative 12-lead ECG showed normal sinus rhythm. Anesthesia was induced with propofol and remifentanil, maintained with sevoflurane, remifentanil and thoracic epidural infusion of lidocaine, fentanyl and levobupivacaine. Bradycardia was detected on ECG 110 minutes after the start of surgery. Intravenous atropine (0.5 mg, repeated up to a total dose of 1.5 mg) was ineffective in restoring a normal heart rhythm. Ten minutes later, the ECG changed to asystole lasting for about 15 seconds. Regular chest compression and intravenous administration of dopamine (5 microg x kg(-1) x min(-1)) resulted in successful recovery of sinus rhythm. Postoperative ECG showed sinus rhythm. The final diagnosis by a cardiologist was concealed sick sinus syndrome. Many anesthetic agents have some effects on the cardiac conduction system. Remifentanil may have played a role in the development of asystole in this patient. The existence of concealed sick sinus syndrome should be kept in mind even in patients who show no clinical abnormalities on preoperative assessment.