Vagal withdrawal during endoscopic retrograde cholangiopancreatography.

Background: Patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) are at risk of developing cardiorespiratory complications, but the mechanism is still unknown. Treatment with metoprolol 2 h before the endoscopy has been shown to decrease the incidence of myocardial ischaemia during ERCP. The present study evaluated whether the endoscopic stress would decrease vagal tone and whether metoprolol given before the procedure could prevent this defence-like reaction. Methods: Thirty-eight patients were randomized to receive either placebo or 100 mg metoprolol 2 h before ERCP. During ERCP the patients were monitored with a Holter tape recorder. Holter tapes from 31 patients (16 receiving metoprolol) were available to analyse the ratio of the standard deviations of the RR intervals (SDRR) to the mean RR intervals (measure of vagal tone) during ERCP. Results: A decreased vagal tone during the ERCP was found, but we observed no difference between the metoprolol and the placebo group. For both gr...