Emerging Technologies: The Introduction of New Technologies into Bariatric and Metabolic Surgery—Are You Ready to Embrace Them?

| September 20, 2008

by Scott Shikora, MD, FACS

Column Editor: Marc Bessler, MD

Dr. Shikora is Professor of Surgery, Chief of MIS, General, and Bariatric Surgery at Tufts Medical Center in Boston, Massachusetts; and President, American Society for Metabolic and Bariatric Surgery (ASMBS).

Introduction
Here’s the good news: Bariatric surgery has never been more popular, safer, or efficacious. Recently, several studies have been published that demonstrate that these operative procedures uniquely improve and even may “cure” a wide range of health conditions, reduce certain cancer risks, improve quality of life, prolong survival, and even pay for themselves in only a few years.1,2 Oh and yes, by the way, they can even achieve meaningful and sustainable weight loss.

Unfortunately, there is also bad news. Despite all of the above-mentioned benefits of these operative procedures, less than one precent of potential patients have bariatric surgery (American Society for Metabolic and Bariatric Surgery-personal communication). This sobering statistic boggles the mind. The etiology of this phenomenon is multifactorial. While some patients may not qualify for surgery, and others may qualify but lack appropriate health insurance coverage, many candidates choose not to have surgery. They do not want to live with the gastrointestinal alterations and/or the risks of potentially devastating complications, or suffer from the long-term nutritional consequences that may result after all of the currently performed operative procedures.

This large, unmet need is fertile ground for the development of new and novel procedures that might be more appealing to patients. To attract patients, these procedures should have several favorable attributes (Table 1). Clearly, they need to be less complex and have a lower complication profile than the current procedures while still achieving the same or similar beneficial results. To that end, a number of new technologies are in development that promise to radically change the face of bariatric surgery in the next decade. Most offer a less complex procedure likely to result in fewer and less severe complications. Some offer new mechanisms of action that do not rely on the traditional caloric restriction and/or malabsorption that are the mainstays of the current procedures. Still others take advantage of the current interest in natural orifice surgery, in which surgeries are performed endoscopically instead of transabdominally.

While the field is rapidly changing, at present the most prominent new technologies in development range from a reincarnation of the gastric balloon to neuromodulation (Table 2).

Intragastric Balloons
The concept of achieving weight loss by placing a balloon into the stomach to occupy space and decrease gastric capacity is not new. In the 1980s, the Garron-Edwards gastric bubble was introduced.3 This single layer silicone balloon that was shaped like a soda can was endoscopically deployed and inflated with saline. However, weight loss was modest at best and serious complications developed. The design of the bubble may have been responsible for these complications. The flat edges of the can-shaped balloon led to pressure ulceration of the stomach and even gastric perforations. The bubble was also single layered and prone to leak. If it leaked and decreased in size, it was at risk for migration into the intestine, which could result in obstruction and intestinal perforation.

Not surprisingly, the Garron-Edwards gastric bubble was pulled from the market and gastric balloon placement abandoned as a treatment option for obesity.3 However, recently, gastric balloons have resurfaced with the introduction of the Allergan Intragastric Balloon (formerly known as the BIB®). This balloon features a new design developed to reduce the risks seen with the gastric bubble. The Allergan Intragastric Balloon is spherical in shape with no edges and is double-layered to reduce the risk of leak. Studies have shown the Allergan Intragastric Balloon to achieve a weight loss of 25 to 35 percent of excess weight with few complications.4,5 While intragastric balloon placement does not appear to represent a primary treatment for morbidly obese patients, it may have a role as a first stage in a staged approach for high risk or super-superobese patients or as a treatment for less severe obesity. Although the gastric balloon is still not FDA-approved in the US, there are now several different balloons available worldwide.

Mechanical Gastric Bands
Laparoscopic adjustable gastric banding is one of the most popular bariatric surgical procedures in the world. However, at present, band adjustments require needle punctures, which have several limitations. First, they can be painful and may lead to bleeding or infection. Second, the instillation of saline is a method that is prone to inaccuracy. Last, band adjustment sometimes requires fluoroscopic assistance, which is expensive and exposes the patient to radiation. In the future, adjustable gastric bands may contain a small “watch” motor than can be accurately adjusted by radiofrequency instead of the current expandable bladder that requires saline instillation. This would eliminate the risks associated with needle punctures.

Natural Orifice Surgery
Natural orifice and endoluminal surgery refers to operating via natural openings such as the mouth, anus, or vagina instead of incisions on the abdominal wall. Conceivably, the concept of operating without the need to make incisions would be very attractive for patients in that there would be less or no postoperative pain, and obviously there would be no scars.

There are several potential applications for natural orifice surgery. It can be used as the access platform for conventional procedures such as the adjustable gastric band, vertical sleeve gastrectomy, and even Roux-en-Y gastric bypass. There have been early reports of cholecystectomies performed via the vagina. Are gastric bands and sleeve gastrectomies far behind? In addition, there are now a number of instruments that have been designed to suture or plicate from inside the stomach endoscopically.6,7 These devices are introduced down the mouth into the stomach either through or alongside an endoscope. These include StomaphyXTM produced by Endogastric Solutions (Figures 4 and 5), TransportTM (Figures 8 and 9) manufactured by USGI Medical, Inc, and Ethicon Endo-Surgey’s Endoscopic Suturing System (Figure 10) manufactured by Ethicon Endosurgery. These devices can be used to volume-reduce dilated gastric pouches, narrow dilated gastrojejunostomies, and even close gastrogastric fistula. Endoscopic gastric partitioning is also being investigated either via endoscopic suturing devices such as the Bard EndocinchTM, the TOGATM device by Satiety (Figures 2 and 3), or the Endoscopic Suturing System. Should these techniques prove successful, it would not be out of the realm of possibility to design a technique for an endoscopic or endoscopic-assisted Roux-en-Y gastric bypass.

While all of these endoluminal and natural orifice procedures appear attractive, to date there have been very little data published, comprising only small patient numbers and limited follow-up. Better data from a greater number of patients with longer follow-up would be necessary to prove that these procedures are truly safe and, more significantly, efficacious.

Endoscopic Gastrointestinal Sleeves
Another endoscopic application is the insertion of an impermeable sleeve into the gastrointestinal tract. In both animal and preliminary human studies, the sleeve has been shown to be effective for weight loss and for improving diabetes.8,9 The EndoBarrierTM (Figure 1) created by GI Dynamics has been demonstrated to be safe and effective with six-month follow-up. The device is a soft, 60cm sleeve that is deployed with an endoscope. The device is anchored into the proximal duodenum and is extended down into the jejunum. It can also be easily endoscopically explanted. In 12 morbidly obese patients, four of which had type II diabetes, there was a 23.6-percent loss of excess weight and all patients could be taken off of their oral hypoglycemic medications.9

The EndoBarrierTM may offer an exciting and safe alternative to traditional bariatric surgery, especially for type II diabetics. However, it is not currently known how long the sleeve can safely be left in the gastrointestinal tract, and the mechanism of action is not yet determined (i.e., nutrient 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 studies demonstrated early satiety and weight loss of approximately 35 percent of excess weight (in patients who responded), larger prospective, randomized, double-blinded 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 26.6-percent 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 14.2-percent loss of excess weight in a six-month period and a proportional reduction of ingested calories.17 A large, multicenter, 300-patient, prospective, randomized, double-blinded 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 conventional Roux-en-Y gastric bypass, these include the ileal transposition (moving a segment of the distal ileum more proximally) with or without sleeve gastrectomy, omentectomy, and the duodenal-jejunal bypass (connecting the proximal duodenum to the jejunum so food bypasses most of the duodenum). Pilot studies with the ileal transposition and the duodenal-jejunal bypass have demonstrated dramatic improvements in diabetes with or without patient weight loss.21,22

Lastly, a duodenal electrical stimulator is being investigated for the treatment of diabetes. Similar to the IGS and Tantalus systems, the procedure involves the laparoscopic implantation of electrodes into the wall of the duodenum. In animal studies, electrical stimulation of the duodenum resulted in reductions in blood sugar and insulin levels (personal communication—BetaStim).

Conclusion

The dramatic increase in demand for surgical remedies for severe obesity and other metabolic disorders has stimulated tremendous interest in developing new technologies and operative procedures. These technologies are striving for less invasiveness, greater safety, lack of permanent alterations of the GI tract, lack of long-term consequences, and even novel mechanisms of action. Although we are entering a very exciting time in bariatric surgery that is rich with rapid change and exciting innovations, keep in mind that currently none of these new modalities has been adequately studied to warrant introduction into practice. Some of these innovations may ultimately be deemed worthy for use, while others will likely fail to achieve meaningful results and be abandoned. Therefore, for the time being… Stay tuned!

References
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Category: Emerging Technologies, Past Articles

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