Feasibility of gastric electrical stimulation by use of endoscopically placed electrodes

Optimization and assessment of a novel gastric electrode anchoring system designed to be implanted by minimally invasive surgery

A novel electrode anchoring design and its implantation procedure, aiming for a minimally invasive solution for gastric electrical stimulation, are presented. The system comprises an anchor made of a flexible body embedding two needle-shaped electrodes. The electrodes can easily switch from a parallel position - to pierce the stomach - to a diverging position - enabling them to remain firmly anchored into the muscular layer of the stomach. Key device parameters governing anchoring stability were assessed on a traction test bench, and optimal values were derived. The device was then implanted in six dogs by open surgery to assess its anchoring durability in vivo. Computed tomography images showed that the electrodes remained well placed within the dogs' gastric wall over the entire assessment period (more than one year). Finally, a prototype of a surgical tool for the minimally invasive device placement was manufactured, and the anchoring procedure was tested on a dog cadaver, providing the proof of concept of the minimally invasive implantation procedure. The use of our electrode anchoring system in long-term gastric electrical stimulation is promising in terms of implantation stability (the anchor withstands a force up to 0.81 N), durability (the anchor remains onto the stomach over one year) and minimal invasiveness of the procedure (the diameter of the percutaneous access is smaller than 12 mm). Moreover, the proposed design could have clinical applications in other hollow organs, such as the urinary bladder.

In Vivo Validation of a Less Invasive Gastrostimulator

Gastrointestinal stimulator implants have recently shown promising results in helping obese patients lose weight. However, to place the implant, the patient currently needs to undergo an invasive surgical procedure. We report a less invasive procedure to stimulate the stomach with a gastrostimulator. After attempting fully endoscopic implantation, we more recently focused on a single incision percutaneous procedure. In both cases, the challenges in electronic design of the implant are largely similar. This article covers the work achieved to meet these and details the in vivo validation of a gastrostimulator aimed to be endoscopically placed and anchored to the stomach.

Bariatric endoscopy: current state of the art, emerging technologies, and challenges

INTRODUCTION

Over the last few decades obesity has become a major health issue worldwide. Although dietary and lifestyle changes are the cornerstone of obesity management, it still poses a huge challenge for the majority of patients to permanently change their eating habits. Bariatric endoscopy represents an evolving filed of minimally invasive techniques and procedures for weight loss trying to respond to these challenges by developing new methods with the increasing role of endoscopists in the management of obesity. Areas covered: The aim of this article is to review the role and the advantages of bariatric endoscopy in the management of obesity by providing a comprehensive reference source and evaluating the currently available and emerging endoscopic devices and techniques for weight loss. Expert commentary: Endoscopic methods for weight loss represent a useful armamentarium in the management of obesity by providing improved effectiveness compared with medications, with a lower risk profile than traditional bariatric surgery. Although preliminary results of recently introduced methods are encouraging, many questions remain regarding the safety and efficacy of such interventions. Combining scientific background with advancements in technology is the key strategy for the further development of bariatric endoscopy.

Recent Trends in Endoscopic Management of Obesity

Obesity remains a tremendous public health, clinical, and scientific challenge globally. Conventional approaches in the management of obesity offer limited potential for sustained weight loss. Bariatric surgery, although it represents the most effective weight loss treatment, has its own risks and is associated with substantial costs and limited patient applicability. Endoscopic weight loss procedures are considered as the major breakthrough in the management of obesity. Endoluminal interventions performed entirely through the gastrointestinal tract have evolved as a result of an attempt to replicate some of the anatomical features and the physiological effects of the traditional weight loss surgery while being reversible, less invasive, and more cost-effective. Restrictive procedures act to decrease gastric volume by space-occupying devices and/or by suturing or stapling techniques that alter gastric anatomy, whereas malabsorptive procedures tend to create malabsorption by preventing food contact with the duodenum and proximal jejunum. Other procedures act by influencing gastric function (gastric botulinum injections, gastric pacing, and vagal nerve blocking) or by gastric aspiration. It is important to underline that the majority of endoscopic weight loss procedures are still being evaluated and are not yet available routinely. Even though some of the techniques and devices that have recently emerged have demonstrated promising short-term results, evidence on their safety and long-term efficacy from well-designed and well-conducted research should be given before they can become an inherent part of everyday clinical practice. Given the rapid development of endoscopic weight loss procedures, this review considers the current state and recent trends in endoscopic management of obesity.

Treating morbid obesity in cirrhosis: A quest of holy grail

The problem of obesity is increasing worldwide in epidemic proportions; the situation is similarly becoming more common in patients with cirrhosis which negatively affect the prognosis of disease and also makes liver transplantation difficult especially in the living donor liver transplantation setting where low graft to recipient weight ratio negatively affects survival. Treatment of obesity is difficult in cirrhosis due to difficulty in implementation of lifestyle measures, limited data on safety of anti-obesity drugs and high risk of surgery. Currently approved anti-obesity drugs have limited data in patients with cirrhosis. Bariatric surgery remains an option in selected compensated cirrhotic patients. Endoscopic interventions for obesity are emerging and are quite promising in patients with cirrhosis as these are minimally invasive. In present review, we briefly discuss various modalities of weight reduction in obese patients and their applicability in patients with cirrhosis.

Advances in the Endoscopic Management of Obesity

Obesity has become a worldwide epidemic with significant impact on quality of life, morbidity, and mortality rates. Over the past two decades, bariatric surgery has established itself as the most effective and durable treatment for patients with obesity and its associated comorbidities. However, despite the use of minimally invasive techniques, bariatric surgery is associated with complications in approximately 15% of patients, has a substantial cost, and is used by only 1% of patients who are eligible. Therefore, there is a need for effective minimally invasive therapies, which will be utilized by the large proportion of obese patients who are in desperate need of treatment but are not receiving any. Endoscopic approaches to the management of obesity have been developed, with the aim of delivering more effective, durable, and safer methods of weight reduction. In this paper, we review currently available and future endoscopic therapies that will likely join the armamentarium used in the management of obesity.

Gastric electrical stimulation for the treatment of obesity: from entrainment to bezoars-a functional review

GROWING WORLDWIDE OBESITY EPIDEMIC HAS PROMPTED THE DEVELOPMENT OF TWO MAIN TREATMENT STREAMS: (a) conservative approaches and (b) invasive techniques. However, only invasive surgical methods have delivered significant and sustainable benefits. Therefore, contemporary research exploration has focused on the development of minimally invasive gastric manipulation methods featuring a safe but reliable and long-term sustainable weight loss effect similar to the one delivered by bariatric surgeries. This antiobesity approach is based on placing external devices in the stomach ranging from electrodes for gastric electrical stimulation to temporary intraluminal bezoars for gastric volume displacement for a predetermined amount of time. The present paper examines the evolution of these techniques from invasively implantable units to completely noninvasive patient-controllable implements, from a functional, rather than from the traditional, parametric point of view. Comparative discussion over the available pilot and clinical studies related to gastric electrical stimulation outlines the promises and the fallacies of this concept as a reliable alternative anti-obesity strategy.

Endoscopic approaches to obesity

Given the emerging role of endoscopic procedures in the treatment of obesity and rapid changes in endoscopic technologies and techniques, this review considers the current state of endoscopic management of obesity. Endoluminal interventions performed entirely through the GI tract by using flexible endoscopy offer the potential for an ambulatory weight loss procedure that may be safer and more cost- effective compared with current surgical approaches. Endoscopic techniques attempt to mimic the anatomic features of bariatric surgery. Accordingly, there are two main endoscopic weight loss modalities - restrictive and malabsorptive. Restrictive procedures act to decrease gastric volume by space-occupying prosthesis and/or by suturing or stapling devices, while malabsorptive procedures tend to create malabsorption by preventing food contact with the duodenum and proximal jejunum. The former include intragastric balloon treatment, endoluminal vertical gastroplasty, transoral gastroplasty and transoral endoscopic restrictive implant system, while the latter include duodenojejunal bypass sleeve. Gastroduodenojejunal bypass sleeve is a combination of both procedures. Except for intragastric balloon, all mentioned procedures are rather new, tested on a small number of human subjects, with a high rate of success, but with limited knowledge on safety and long-term efficacy. The role of gastric electrical stimulation and intragastric injections of botulinum toxin in obesity treatment is also considered as is the role of minimally invasive bariatric endoscopic interventions.

Short pulse gastric electrical stimulation for cisplatin-induced emesis in dogs

BACKGROUND

In a previous study, we investigated the ameliorating effect of gastric electrical stimulation (GES) with a single set of parameters on emesis and behaviors suggestive of nausea induced by cisplatin in dogs. The aim of this study was to investigate the effects of GES with different parameters on cisplatin-induced emesis in dogs.

METHODS

Seven dogs implanted with gastric serosal electrodes were studied in six randomized sessions: one control session with cisplatin (2 mg kg(-1)) and five sessions with cisplatin plus GES of different parameters: GES-A: 14 Hz, 5 mA, 0.3 ms, 0.1 s on and 5 s off; GES-B: increased frequency and on-time; GES-C: increased frequency; GES-D: increased frequency and pulse width; and GES-E: increased frequency and amplitude. Gastric slow waves and emetic responses were recorded in each session.

KEY RESULTS

(i) Cisplatin induced emetic responses and gastric dysrhythmia. The peak time of the emetic response was during the fourth hour after cisplatin. (ii) GES with appropriate parameters reduced cisplatin-induced emesis. The number of vomiting times during the 6 h after cisplatin was 7.0 ± 1.4 in the control, 4.7 ± 1.2 with GES-A (P = 0.179), 4.2 ± 1.2 with GES-B (P = 0.109), 7.0 ± 0.8 with GES-C (P = 0.928), 2.1 ± 0.3 with GES-D (P = 0.005) and 4.7 ± 1.5 with GES-E (P = 0.129). However, none of the GES parameters could improve gastric dysrhythmia.

CONCLUSIONS & INFERENCES

Gastric electrical stimulation with appropriate parameters reduces cisplatin-induced emetic responses and behaviors suggestive of nausea in dogs. Among the tested parameters, GES with increased pulse width seems to produce better relief of cisplatin-induced emesis.

Mechanisms and potential applications of intestinal electrical stimulation

PURPOSE

Electrical stimulation of the gut has recently been under intensive investigation and various studies have revealed therapeutic potentials of gastrointestinal electrical stimulation for gastrointestinal motility disorders and obesity. While there have been a number of reviews on gastric electrical stimulation, there is a lack of systematic reviews on intestinal electrical stimulation. The aim of this review is to provide an overview on the effects, mechanisms, and applications of intestinal electrical stimulation.

RESULTS

We evaluated published data on intestinal electrophysiology, pathophysiology, and different methodologies on intestinal electrical stimulation and its possible mechanisms in both research and clinical settings using the MEDLINE database for English articles from 1963 to 2008. Based on this systematic review, intestinal electrical stimulation has been reported to alter intestinal slow waves, contractions and transit; the effects were mediated via both vagal and adrenergic pathways. Intestinal electrical stimulation has been reported to have potentials for treating various intestinal motility disorders and obesity.

CONCLUSIONS

It is concluded that intestinal electrical stimulation may have promising applications for treating motility disorders associated with altered intestinal contractile activity. The most recent studies have revealed possible applications of intestinal electrical stimulation for the treatment of obesity. Basic research results are promising; however, further clinical studies are needed to bring IES from bench to bedside.

Emerging technology: endoluminal treatment of obesity

BACKGROUND

Bariatric surgery remains the most effective treatment for the management of obesity. Endoluminal interventions offer the potential for an ambulatory weight loss procedure that may be safer and more cost-effective compared with current laparoscopic approaches.

OBJECTIVE

We review the currently available endoluminal techniques for obesity that have been presented or discussed in public forums and meetings, focusing on those with published trials.

DESIGN

Literature review.

RESULTS

Human trials of endoluminal treatments of obesity are primarily limited to restrictive interventions, including intragastric balloons, transoral gastroplasty, and endoluminal vertical gastroplasty. Currently, the duodenojejunal bypass sleeve is the only endoluminal device that has been studied in humans that promotes weight loss through malabsorption. Early results of these technologies are promising, but long-term data are lacking.

CONCLUSIONS

Endoluminal treatments for obesity have promise, and recent technological advances have been astounding. However, these interventions will need to be held to the same standards of current operative techniques. Each device will need to be scrutinized within clinical trials to determine its safety, efficacy, and durability.

Diabetic gastroparesis: diagnosis and management

Gastric emptying is frequently abnormal in patients with long-standing type 1 and type 2 diabetes mellitus. Symptoms commonly associated with disordered gastric emptying include nausea, vomiting, bloating and epigastric pain, while patients are also at risk of malnutrition, weight loss, impaired drug absorption, disordered glycaemic control and poor quality of life. Although often attributed to the presence of irreversible autonomic neuropathy, acute hyperglycaemia represents a potentially reversible cause of gastric dysfunction in diabetes. Scintigraphy represents the gold standard for measuring gastric emptying. The management of diabetic gastroparesis is less than optimal, partly because the pathogenesis has not been clearly defined. Treatment approaches include dietary modification and optimization of glycaemia, and the use of prokinetic drugs, while novel therapies such as gastric electrical stimulation are the subject of ongoing investigation.

Feasibility of gastric electrical stimulation by percutaneous endoscopic transgastric electrodes

BACKGROUND

Gastric electrical stimulation has been used for the treatment of drug refractory GI motility disorders and for the treatment of obesity. Both these indications have involved surgical placement of gastric electrodes, which adds to the complexity and cost of the procedure. Endoscopic placement is therefore an attractive alternative approach for this therapy.

OBJECTIVE

Our purpose was to investigate the feasibility, safety, and efficacy of percutaneous endoscopic electrodes for gastric electrical stimulation.

DESIGN AND SETTING

Experimental animal study in hound dogs.

INTERVENTIONS

Percutaneous endoscopic transgastric electrode (PETE) placement was carried out by using a pair of gastric pacing wires attached to a percutaneous endoscopic gastrostomy tube. In addition, 4 pairs of gastric serosal electrodes were implanted surgically for comparison. The efficacy of the percutaneous endoscopic electrodes was defined by their ability to entrain gastric slow waves and the induction of dysrhythmia.

RESULTS

(1) The PETE recorded gastric slow waves comparable to the serosal electrodes. (2) Gastric electrical stimulation with long pulses delivered by the PETE, at a frequency of 10% higher than the intrinsic gastric slow wave frequency, entrained gastric slow waves. (3) Gastric electrical stimulation delivered by the PETE, at a tachygastric frequency, induced gastric dysrhythmia.

LIMITATIONS

This was an animal study; however, its results are expected to be reproducible in humans, with PETE kept in place for even a longer duration than 6 to 8 weeks.

CONCLUSION

PETE placement is both feasible and safe. PETEs are effective, having a potential for use in treatment of both gastroparesis and obesity.