Biliary, pancreatic, and sphincter of Oddi electrical and mechanical signals recorded during ERCP

Clinical application and research progress of extracellular slow wave recording in the gastrointestinal tract

The physiological function of the gastrointestinal (GI) tract is based on the slow wave generated and transmitted by the interstitial cells of Cajal. Extracellular myoelectric recording techniques are often used to record the characteristics and propagation of slow wave and analyze the models of slow wave transmission under physiological and pathological conditions to further explore the mechanism of GI dysfunction. This article reviews the application and research progress of electromyography, bioelectromagnetic technology, and high-resolution mapping in animal and clinical experiments, summarizes the clinical application of GI electrical stimulation therapy, and reviews the electrophysiological research in the biliary system.

The Effect of Gastric Electrical Stimulation on Small Bowel Motility in Patients With Gastroparesis and Concomitant Pancreatic and Small Bowel Dysfunction: From Animal Model to Human Application

BACKGROUND/AIMS

Patients with gastroparesis often have biliary/pancreatic and small bowel symptoms but the effects of gastric electrical stimulation on small bowel electrical activity of the mid-gut have not been studied. Animal model aim: Establish gastric and upper small bowel/biliary slow wave activity relationships with electrical stimulation. Human study aim: Demonstrate improvement in symptoms associated with proximal small bowel dysmotility in gastric stimulated patients.

MATERIALS AND METHODS

Animal model: In vivo evoked responses of duodenal and Sphincter of Oddi measures recorded during gastric electrical stimulation in a nonsurvival swine model (N = 3). High-resolution electrical slow wave mapping of frequency, amplitude, and their ratio, for duodenal and Sphincter of Oddi electrical activity were recorded. Human study: Patients (N = 8) underwent temporary gastric stimulation with small bowel electrodes. Subjective and objective data was collected before and after temporary gastric stimulation. Symptom scores, gastric emptying times, and mucosal electrograms via low-resolution mapping were recorded.

RESULTS

Animal gastric stimulation resulted in some changes in electrical activity parameters, especially with the highest energies delivered but the changes were not statistically significant. Human study revealed improvement in symptom and illness severity scores, and changes in small bowel mucosal slow wave activity.

CONCLUSIONS

Gastric electrical stimulation in an animal model seems to show nonsignificant effects small bowel slow wave activity and myoelectric signaling, suggesting the existence of intrinsic neural connections. Human data shows more significance, with possible potential for therapeutic use of electrical stimulation in patients with gastroparesis and pancreato-biliary and small bowel symptoms of the mid-gut. This study was limited by the nonsurvival pig model, small sample size, and open label human study.

Reduced myoelectric activity in the sphincter of Oddi in a new model of chronic cholangitis in rabbits: an in vivo and in vitro study

BACKGROUND

Chronic cholangitis caused by hepatolithiasis is a common disease in Southeast Asia. Few studies have addressed the effects of chronic cholangitis on cyclic activity of the sphincter of Oddi (SO). In this study, we investigated the changes of myoelectric activity in rabbits with chronic cholangitis in vivo and in vitro.

METHODS

Chronic cholangitis was induced in rabbits by initially introducing three pieces of 2-0 silk suture and sequentially injecting E. coli into the choledochus through the tube in ductus cysticus. In in vivo experiments, myoelectric activity of SO was recorded by a circular electrode through the jejunum stump in conscious animals. In in vitro experiments, the SO was completely isolated and the myoelectric activity was recorded by a circular electrode in a 10-mL organ bath filled with Krebs solution, with or without addition of cholecystokinin-8 (CCK-8), KCl, ionomycin or induction of capacitative calcium entry (CCE).

KEY RESULTS

In comparison with control and non-infected rabbits, the rabbits with chronic cholangitis showed higher levels of alkaline phosphatase and gamma-glutamyltransferase and significant pathological changes including increased inflammatory infiltration and collagen deposition in mucosae or muscular layer. Cyclic myoelectric activity of SO at phases 2 and 3 of migrating motor complex and the excitatory response to CCK-8 were dramatically decreased in animals with chronic cholangitis. Myoelectric activity of SO was also significantly decreased in vitro with or without agonists or with induction of CCE.

CONCLUSIONS & INFERENCES

Myoelectric activity of SO and its response to agonists are decreased in rabbits with chronic cholangitis both in vivo and in vitro.

The feasibility and reliability of using circular electrode for sphincter of Oddi electromyography in anaesthetised rabbits

Sphincter of Oddi manometry (SOM) is the gold standard for assessing sphincter of Oddi dysfunction (SOD), but is considered a diagnostic sensitivity of 30-80% and associated with significant complications of pancreatitis. Electromyography (EMG) of sphincter of Oddi (SO) using a circular electrode (CE) may be useful in improving diagnostic accuracy and reducing complications. To evaluate the feasibility and reliability of the CE, we record myoelectric activity of SO in rabbits using the CE to compare with the traditional needle electrode (NE). The CE was prepared using a double-channel biogel catheter with two silver rings at the head of the catheter. The CE was then inserted into the lumen of the SO through the duodenal papilla, and myoelectric activity was recorded in the SO in 30 rabbits. An EMG recorded using an NE was performed at the same time, when the SO was in basal state, after injection of cholecystokinin and N-butylscopolamine bromide. Electromyographs recorded by the two methods were then evaluated. Satisfactory SO EMGs were acquired using the CE without any injury. Simultaneous recording revealed a very similar traces and one-to-one correspondence of SO spike bursts (SOSB). Linear regression analysis showed a significant direct correlation between the two methods for SOSB duration and amplitude. The results suggested that CE was comparable with NE in terms of recording efficacy. The CE also has advantages of easy fixation, accurate localisation, broad applicability and ease of achieving satisfactory outcomes without trauma, compared with the NE.