Biliary, Pancreatic, and Sphincter of Oddi Electrical and Mechanical Signals Recorded During ERCP

Abstract

Measurements of biliary tract motility havefocused on radiologic and pressure measurements toquantify biliary motility rather than measurements ofelectrical activity of the biliary tract. We previously reported the recording of biliary electricalsignals during ERCP and now report on the continueddevelopment and validation of a system to measurebiliary tract electrical activity as well as biliarymechanical activity. In 26 patients presenting with avariety of clinical indications, we recordedmeasurements of electrical activity from the common bileduct sphincter (16 patients), pancreatic duct sphincter(eight patients), and/or sphincter of Oddi (eightpatients). Electrical recordings were performed with aspecially modified ERCP catheter, using two circularelectrodes as well as a custom catheter that measured both electrical and mechanical activity.Electrical activity of the biliary tract wassuccessfully recorded in 25 of 26 patients (96%),including the common bile duct sphincter (16 patients,62%), pancreatic duct sphincter (eight patients, 31%) andsphincter of Oddi (eight patients, 31%). Along with theelectrical recordings, common bile duct sphinctermechanical activity was recorded in 12 patients (67%), pancreatic duct sphincter mechanical activityin six patients (33%), and sphincter of Oddi mechanicalactivity in six patients (33%). Frequency analysis ofelectrical signals revealed a mean frequency(cycles/min) of 4.7 ± 0.5 in the common bile ductsphincter, 4.1 ± 0.6 in the pancreatic ductsphincter, and 4.9 ± 0.7 in the sphincter ofOddi. Phasic mechanical frequency in cycles per minutewas recorded at a frequency of 4.8 ± 0.5 in common bileduct sphincter, 4.0 ± 0.6 in pancreatic ductsphincter, and 5.3 ± 0.9 in sphincter of Oddi.Tonic pressure (averaged 12.1 ± 1.5 mm Hg) incommon bile duct sphincter, 12.4 ± 1.4 mm Hg inpancreatic duct sphincter, and 15.0 ± 5.1 mm Hgin sphincter of Oddi. Analysis of wave form propagations(noted as percentage antegrade, retrograde, orindeterminant) revealed 50% antegrade, 23% retrograde, and 27%indeterminant). One patient was recorded on twooccasions via ERCP; the same patient had anintraoperative recording. All three recordings showedsimilarities. We conclude that measurements of biliary,pancreatic, and sphincter of Oddi electrical andmechanical activity are feasible and can be done as partof ERCP. There was good correlation between biliarytract electrical and mechanical events and differentwave form characteristics were noted for different partsof the biliary tree. Further studies are warranted toevaluate the potential usefulness of measurement of biliary tract electrical activity, and toconfirm its correlation with mechanical events in thepancreato-biliary tree.