Factors that affect the variability in heart rate during endoscopic retrograde cholangiopancreatography.

OBJECTIVE: To find out if drugs, position, and endoscopic manipulation during endoscopic retrograde cholangiopancreatography (ERCP) influence the changes in the variability of heart rate. DESIGN: Single-blind randomised trial. SUBJECTS: 10 volunteers given butyscopolamine, glucagon, or saline intravenously on three different study days, and 10 patients who had ERCP without butylscopolamine or glucagon. MAIN OUTCOME MEASURES: Holter tape analysis for ischaemia and changes in the variability of heart rate. RESULTS: 5 volunteers developed tachycardia after butylscopolamine, while 2 developed tachycardia after glucagon. During ERCP 9 patients developed tachycardia, and 2 developed myocardial ischaemia. Vagal tone decreased in the volunteers after butylscopolamine, but no changes were seen after glucagon or placebo, or in patients during ERCP. CONCLUSIONS: Butylscopolamine reduced vagal tone in volunteers. Patients who were having ERCP without butylscopolamine had a stable vagal tone. The previously observed reduced vagal tone during ERCP may therefore be primarily the result of giving butylscopolamine.