Bariatric Times - September 2008 - (Page 16)

16 Emerging Technologies Bariatric Times • September 2008 Pilot studies with the ileal transposition and the duodenaljejunal bypass have demonstrated dramatic improvements in diabetes WITH OR WITHOUT PATIENT WEIGHT LOSS. TABLE 1. Desired Advantages of New Technologies 21,22 • Less invasive, less complex • Safer, fewer and less serious complications • Fewer or no long term sequelae • New mechanisms of action • Less expensive and/or resource dependent • Truly reversible TABLE 2. Directions for New Technologies malabsorption, alterations of gut hormones, changes in gastrointestinal nerve function, and reaction to a chronic foreign body). NEUROMODULATION Another novel and exciting class of new technologies is referred to as neuromodulation. This entails utilizing an electrical pulse generator (similar to a heart pacemaker) to deliver a patterned electrical impulse to a target on the gastrointestinal tract. That target could be the stomach, the intestines, the nerves, etc. The impulse can be used to stimulate or enhance the normal electrical activity or block it. Currently, there are many applications of neuromodulation that are being investigated (Table 3). Several animal studies have demonstrated that gastrointestinal stimulation could result in a reduction in food intake and weight loss.10,11 However, the exact mechanism of action has not yet been determined. The first human trials were conducted with the implantable gastric stimulation system (IGS). This procedure involved the laparoscopic implantation of bipolar electrical leads into the wall of the stomach and attaching them to an electrical pulse generator placed under the skin. The procedure took approximately one hour or less to complete and patients were able to go home shortly thereafter. Several studies were conducted throughout the world, involving over 800 patients. The procedure proved to be extremely safe as there were no serious complications. It also does not appear to alter the gastrointestinal tract anatomy or physiology and was easily reversible and adjustable. While preliminary • Intragastric balloons and bezoars • New generations of gastric bands • Endoscopic gastric partitioning and/or bypass • Endoscopic gastric sleeves and stents • Neuromodulation • Metabolic Surgery TABLE 3. Gastrointestinal Neuromodulation • Vagal nerve stimulation (Cyberonics) • Sympathetic nerve stimulation (Leptos) • Intragastric stimulation (Intrapace) • Implantable intestinal stimulation (BetaStim) • Implantable gastric stimulation • Continuous stimulation (Medtronic) • Meal-activated stimulation (Metacure) studies demonstrated early satiety and weight loss of approximately 35 percent of excess weight (in patients who responded), larger prospective, randomized, doubleblinded trials had inconsistent results.12-15 Unfortunately, like the animal studies, the mechanism of action was not identified (i.e., gastrointestinal motility, neuroendocrine alterations, vagal stimulation, central mechanisms). Furthermore, the characteristics of patients likely to succeed and the proper programming of the device have also not been determined. Until these issues are resolved, it is unlikely that this technology will be consistently effective. More recently, a meal-activated gastric stimulation system was developed called the TantalusTM System. Unlike the IGS, which was a continuous system, the TantalusTM System would only be activated by eating. In a preliminary study with this device, 12 morbidly obese patients demonstrated a 26.6percent loss of excess weight at one year.16 However, like the IGS, not all patients responded. In contrast to gastrointestinal stimulation, “neuroblocking” as a means of achieving weight loss is also under investigation. The VBLOCTM system (Figures 6 and 7), developed by EnteroMedics, involves the laparoscopic placement of electrodes onto the trunks of the vagus nerves and the delivery of an electrical impulse sufficient enough to interrupt all vagal nerve function. It is believed that 80 percent of the vagus consists of afferent nerve fibers that bring information from the gastrointestinal (GI) tract to the brain. By blocking these signals, it is thought that the brain would be tricked into believing that the GI tract was postprandial. Preliminary studies have reported a 14.2percent loss of excess weight in a six-month period and a proportional reduction of ingested calories.17 A large, multicenter, 300-patient, prospective, randomized, doubleblinded trial is currently underway. BARIATRIC SURGERY IS BECOMING METABOLIC SURGERY No discussion of new technologies and procedures in bariatric surgery would be complete without a discussion of the emerging interest in metabolic surgery, (i.e., surgical procedures performed to target metabolic diseases such as diabetes). While all of the contemporary bariatric procedures are successful for achieving meaningful and sustainable weight loss, it is the resolution of metabolic conditions like diabetes that is currently getting the most attention. The relationship between the GI tract and metabolic disease has been known for decades. In 1955, Friedman et al reported on the amelioration of diabetes following gastrectomy for ulcer disease in non-morbidly obese patients.18 In 1995, Pories et al found similar results with gastric bypass surgery in the morbidly obese.19 Recently, Rubino et al performed elegant animal studies that suggested that the amelioration of diabetes after bariatric surgery may be hormonal in etiology as opposed to weight reduction.20 However, the changes in caloric intake postoperatively have not been examined as a possible alternative explanation. Currently, a number of gastrointestinal operations have been developed and are being evaluated as potential treatments for diabetes. In addition to the FIGURE 4. EndoGastric Solutions currently markets a device under the trade name StomaphyX®, which can deploy polypropylene T-fasteners endoscopically. FIGURE 5. T-fastener is fired through the gastric wall to approximate the tissue.

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Bariatric Times - September 2008 Emerging Technologies Case Report Sleeve Gastrectomy after a Jejunoileal Bypass Reversal Editorial Message Contents Editorial Board Walk from Obesity The Latest on Nutrition and Hair Loss in the Bariatric Patient Consultant’s Corner Journal Watch Calendar of Events Advertiser Index

Bariatric Times - September 2008

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