Natural Orifice Bariatric Surgery: An Update

| November 7, 2008

by Atul K. Madan, MD, FACS and Jose M. Martinez, MD, FACS

Division of Laparoendoscopic and Bariatric Surgery, Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida.

Natural orifice transluminal surgery (NOTES) has the potential of changing bariatric surgery just as laparoscopy did almost two decades ago. The challenge of adopting NOTES is the requirement of creating an incision in an organ that is otherwise healthy. Depending on the organ, it may be difficult to justify the exchange of incisions on the abdominal wall for incisions on another organ. Many bariatric surgery procedures require entry or incision on the stomach. Vertical banded gastroplasty, Roux-en-Y gastric bypass, biliopancreatic diversion, and sleeve gastrectomy require the stomach to be breached during the normal course of the operation. These operations make it easy to justify transgastric NOTES approaches. Work is being performed to develop a NOTES bariatric procedure at the present time. Furthermore, there are endoluminal procedures that are being trialed as substitutes for the current bariatric procedures. Some of these procedures have been performed on human subjects already. This article will review the current literature on natural orifice and endoluminal procedures being developed for bariatric surgery.

Endoluminal Procedures for Primary Bariatric Surgery
Endoscopic treatment of obesity is an attractive option. While bariatric surgery is relatively safe today, it is not without its complications. For example, gastrointestinal leaks can be the cause of major morbidity and mortality after Roux-en Y gastric bypass.10 Thus, various procedures are being developed for weight loss without transecting the stomach. Although some operations, such as laparoscopic adjustable gastric banding, currently being performed do not require entry into the gastrointestinal tract, many endoluminal procedures eliminate the issues with a foreign body as well as entering the peritoneal cavity.
With the development of endoscopic suturing devices, surgeons began animal studies on performing an endoluminal gastroplasty. For example, Awan and Swain1 reported an endoscopic vertical banded gastroplasty with the use of an endoscopic sewing machine (ESM; C.R. BARD Inc., Murray Hill, New Jersey). They utilized explanted porcine gastric stomachs to perform their procedure. These authors sutured a ring to the interior stomach to mimic the external band of the usual vertical banded gastroplasty. The concerns of ring dislodgement and/or erosion could not be addressed in this feasibility study on explanted stomachs.

In addition, Hu et al6 reported the use of a prototype suturing device called the Eagle Claw VII.6 This device is being designed and manufactured by Olympus Corporation (Toyko, Japan) and the Apollo Group. In an explanted porcine stomach, they were able to create a proximal gastric pouch of approximately 100cc. The authors admitted that the size of their pouch may be too large for weight loss in a morbidly obese patient. However, their goal was to demonstrate the feasibility of performing a purely endoluminal procedure to decrease the volume of the stomach.

The same group published another set of experiments in four live animals.8 They demonstrated a similar technique with the Eagle Claw VII in a porcine model. However, this time they were able create a much smaller pouch, approximately 30cc in size. Since the investigation was designed as an acute study, short-term—let alone long-term—success was not evaluated.

One concern of utilizing endoscopic suturing methods is that the sutures only allow mucosa-to-mucosa apposition. It is unknown if this apposition will actually produce durable results. Another group attempted an endoluminal vertical gastroplasty; however, this time it was with endoscopic staplers.3 They utilized the Transoral Gastroplasty (TOGA) System (Satiety Inc., Palo Alto, California), as shown in Figure 1. This system allows the endoscopist to place a stapler via the mouth to form a gastroplasty. Their system allowed for a transmural staple line to be placed, which created a serosa-to-serosa apposition. The first staple line is placed at the angle of His parallel to the lesser curvature. Another staple line was placed below that in most of the patients. A “restrictor” is placed at the end of the stapler line. Their first study included 21 patients with no serious adverse events. In the beginning of the study, the investigators utilized a laparoscopic view to ensure that there was no inadvertent injury to adjacent organs. However, they later abandoned laparoscopy as they felt that this was additive to potential risk with little benefit. Their early results demonstrated a 24.4-percent excess weight loss at six months. Longer-term data were not reported.

The first study revealed a technical issue with their system. There were a large number of staple “gaps.” These gaps occurred between the first staple and the angle of His as well as at the first and second staple lines. The system was redesigned to create overlapping staple lines to reduce the incidence of these gaps. A second study, with 11 patients, revealed even more impressive results than the first study.13 At six months, the average excess weight loss was 46 percent. Unfortunately, two patients had large outlet sizes at three months and, despite having re-treatment, did not have appropriate weight loss. Nevertheless, the overall short-term weight loss data are promising.

Of course, along with the dilation of the “pouch”/outlet, long-term staple line dehiscence is another issue that may occur. Thus, long-term followup is required to determine if this procedure is the first viable transluminal bariatric procedure that should be offered to the morbidly obese. The authors state that a multi-center trial is being planned, which should be helpful in validating their short-term results as well as hopefully providing long-term results of their system.

Another endoluminal device being investigated for weight loss is the EndoBarrierTM (GI Dynamics, Watertown, Massachusetts), as shown in Figure 2. Instead of focusing on a primary restrictive mechanism, this device focuses on bypassing the duodenum and first part of the jejunum via an endoscopic bypass sleeve. Tarnoff et al19,20 reported their experience in placing a 60cm duodenal-jejunal bypass sleeve (DJBS) in a live porcine model. First, they reported the acute feasibility and safety of placing this device.19 The investigators placed the device and the retrieved it only after leaving it in place for less than an hour. Four days later, the animals were sacrificed. They found no pathological issues with the gastrointestinal tract at necropsy. Their follow-up study20 involved six animals. Four of the animals were kept alive for three months, while two of the animals were kept alive for four months. There were some issues with the anchors that were utilized to hold the sleeve in place; however, transmural erosion was not seen in any case. They did note that there was a statistically significant difference in the average weight gain between the test and sham groups.

Rodriquez-Grunert et al14 placed the EndoBarrierTM in 12 human patients. They performed a prospective, open-label, single-center study to evaluate the device. Their study was limited to 12 weeks. The procedures were done under general anesthesia with endoscopy and fluoroscopy. The device is deployed in the duodenal bulb. The anchoring system is self-expanding, allowing the barbs to attach to the gastrointestinal tract to decrease the risk of migration. The barbs are protected when the device is placed into the esophagus and stomach until deployment. To remove the device, there are proximal drawstrings that collapse the anchoring system. There is a retrieval “hood” that is designed to reduce the risk of injury to the gastrointestinal tract by the barbs during removal.

They were able to deliver and retrieve their DJBS in all 12 patients, but two patients required exploration to remove the device earlier than the 12 weeks due to abdominal pain. In addition, two patients had mucosal tears during the removal of the device (1 oral-pharyngeal and 1 esophageal). The average excess weight loss in the 12 week period was 23.6 percent. When evaluating the four patients with diabetes, three of the patients did not require their oral diabetic medication only 24 hours after implantation. The other patient demonstrated no improvement.

The EndoBarrier is currently being evaluated in a Food and Drug Administration (FDA)-approved trial. Gersin et al4 described the first human case performed in North America. The patient lost a total of 9.09kg and had no problems after removal of the device. The overall role of the use of a DJBS is still unknown. While the FDA trial is being utilized to test the efficacy of weight loss before bariatric surgery, whether this technology will be utilized as a sole therapeutic intervention for the morbidly obese is unknown. Furthermore, the results of the FDA trial are still pending. Most importantly, the mechanisms of weight loss and diabetic resolution with the EndoBarrierTM need to be further elucidated.

Endoscopically placed intragastric balloons have been studied for the treatment of morbid obesity for over two decades.7 While technological refinements have occurred, currently no intragastric balloon has been approved in the US by the FDA. There are various types of intragastric balloons that have been described, including the Bioenterics Intragastric Balloon (Allergan, Irvine, California), the Heliosphere (Helioscopie, Rhone-Alpes, France), Danish Ballobes (DOT APS, Rodovre, Denmark), and Garren-Edwards Gastric Bubble (American Edward Lab., Inc., Santa Ana, California). The most widely utilized balloon is the Bioenterics Intragastric Balloon (Figure 3). A recent meta-analysis concluded that this intragastric balloon, along with a weight management program, has the ability to provide short-term weight loss.23 Not enough data were available to make conclusions about long-term efficacy.

There are other devices that are being developed for weight loss,15 one of which is the Silhouette Medical ablation system (Silhouette Medical, Mountain View, California). The goal of this device is to ablate the pylorus to impair gastric emptying. Due to the interest of gastric stimulation for the treatment of morbid obesity,22 IntraPace, Inc. (Menlo Park, California) is developing a gastric pacemaker for the treatment of obesity that can be placed endoscopically. There are no published data to date on either the Silhouette Medical ablation system or the IntraPace device.

Endoluminal Procedures for Revisional Bariatric Surgery
Revisional bariatric surgery for inappropriate weight loss and/or weight regain poses a challenge to bariatric surgeons. Part of the issue is that the exact mechanism of weight loss after gastric bypass is still not precisely known. Most likely weight loss occurs through a combination of mechanisms. Some of the potential mechanisms are bypassing the proximal small bowel, malabsorption, restricted gastric pouch size, and limited gastrojejunostomy stoma size. If stoma size (which limits emptying of the pouch and thus sustained feeling of early satiety) is a significant determinant of successful weight loss, then weight loss may reoccur if the size is reduced in unsuccessful patients who have dilated gastrojejunostomies.

This theory has led investigators to attempt endoscopic reduction of stoma size. Reduction can occur utilizing endoscopic suturing, endoscopic injection of sclerosing agents, or utilized specialized endoscopic devices. Sclerotherapy was first reported by Spaulding.17 The chosen agent utilized was sodium morrhuate, which has been known to cause strictures when injected deeply. The initial report of 20 patients demonstrated that 75 percent lost weight with an average of nine-percent weight change six months after sclerotherapy. The average amount of sodium morrhuate injected was 6cc. A more recent publication with over one-year followup of 32 patients demonstrated a reversal of a 0.36kg/month weight gain to a 0.39kg/month weight loss.18 Over half the patients began to lose weight and over 90 percent had weight loss or stabilization. One weakness of their data was that only 32 of the 147 patients who underwent sclerotherapy had one year or more followup.

Others have reported similar mixed results with sclerotherapy. For example, Lowen and Barba9 studied 71 patients. In their investigation, 21 (30%) patients lost weight and 20 (28%) patients gained weight, but 30 patients had no change in their weight. They injected an average of 13cc of sodium morrhuate. Catalano et al,2 however, reported a much higher rate of weight loss (average 22.3kg) in 28 patients. The injected larger quantities of sodium morrhuate with a range 8 to 20ccs (average=14.5ccs). They injected enough to cause the tissue to turn a deep purple. One patient, however, required dilation due to a stenosis. Our personal unpublished experience mimics the reported literature in that about half of the patients have some weight loss with endoscopic sclerotherapy. Figure 4 demonstrates a before-and-after view comparison of sclerotherapy. Since 50 percent of the patients may receive a benefit, we find it reasonable to consider this endoluminal therapy as a current option for unsuccessful patients who have a dilated gastrojejunostomy after gastric bypass.

Other techniques have been utilized to reduce the size of the stoma. These techniques rely on suturing devices that were developed for other applications, such as gastroesophageal reflux disease. For example, the Flexible Endoscopic Suture Device (Wilson-Cook; Winston-Salem, North Carolina) Schweitzer utilized to reduce the stoma size and gastric pouch size in four patients.16 Unfortunately, no weight loss data were presented. In addition, Thompson et al21 utilized the EndoCinch System to perform endoluminal reduction of dilated gastrojejunostomy. In their report of eight patients, six had lost an average of 10kg during the mean follow-up of four months. The limited depth of the placed sutures is a concern for the durability of such a reduction.

Herron et al5 recently described pouch and stoma reduction via the USGI Endosurgical Operating System (USGI Medical, Inc., San Clemente, California). This was performed first in an ex-vivo porcine model and then in a live porcine model. The operating system involves two components, the TransPort and the g-Prox (Figure 5). The Transport is a steerable, flexible, multilumen, endoscopic access device whose body can be locked and the tip still remain steerable. The g-Prox is a flexible instrument that can grasp and approximate tissue. It can deploy tissue anchors. These tissue anchors are described as two disc-shaped anchors connected by suture material. The touted advantage of this device is that it can be reloaded without removing it from the operative field. Additionally, other instruments (such as scissors) can be placed through the other lumens of the Transport device. With this operating system, the authors were able to decrease the pouch volume by 30 percent and the stoma diameter by 50 percent. Actual weight loss was not studied in their study. Since this device has just recently received FDA approval, the authors have initiated a multicenter study for its use in humans.

StomaPhyx (EndoGastric Solutions, Inc., Redmond, Washington) is another device that has been utilized for reducing pouch and stoma size (Figure 6). While it is FDA approved, no published literature is available on the short- or long-term results. This device also employs full-thickness plications to decrease the pouch and stoma size. StomaPhyx may also may a reasonable current option for patients who have dilated gastrojejunostomies and/or enlarged pouches.

This concept of decreasing the pouch and/or stoma size endoluminally demonstrates another avenue to revise gastric bypass surgery. The few long-term results from sclerotherapy are promising; however, newer technologies that employ more durable and consistent methods of pouch and/or stoma reduction may become the standard treatment in patients who either gain weight or lose insufficient weight after gastric bypass.

Experimental NOTES Procedures for Primary Bariatric Surgery
True NOTES bariatric surgery has not yet been reported in live, human, morbidly obese patients. However, experimental procedures are being tested. Mintz et al12 performed a hybrid NOTES sleeve gastrectomy in a porcine model. They report their experience utilizing abdominal and rectal entry sites to perform their sleeve. Briefly, a 5mm trocar and laparoscope was placed for pneumoperitoneum and visualization. They placed a 12mm or 15mm transanally through the rectal wall. Stay sutures via the anterior abdominal wall were placed into the stomach to aid retraction and exposure. A stapler was placed through the transrectal trocar to divide the stomach. The short gastric vessels were taken via a harmonic scalpel. The stomach was extracted through the proctotomy and transanally. These were acute animal studies, but the staple lines were intact at necropsy.

Our group has previously reported a NOTES Roux-en-Y gastric bypass in a human cadaver (Figure 7).11 In addition, we have performed similar experiments in the porcine model. While various techniques can be utilized to perform a NOTES Roux-en-Y gastric bypass, we initiated the bypass via a transoral, transgastric entry site for the endoscope. A laparoscope was placed to record the procedure. After entering the peritoneum via the stomach, two more peritoneal entry sites are established with long laparoscopic trocars through the vagina. In the porcine model, a rectal entry site is substituted for the second vaginal entry site.

The first step is a finding the ligament of Treitz. The bowel is transversed about 50cm distally and then divided. A jejunojejunostomy is formed about 100cm distal in a double-staple technique, end-to-side fashion. Enterotomies are made with laparoscopic scissors from one of the pelvic trocars. A laparoscopic computer-mediated stapler (Power Medical Interventions; New Hope, Pennsylvania) is placed via the pelvic trocar for this anastomosis.

The gastric endoscope is removed from the stomach. Staplers from the pelvic trocars are utilized to create a gastric pouch. The gastric endoscope is placed back to help manipulate the stomach, which helps with appropriate placement of the stapler especially when the angles are awkward. The computer-mediated circular (Power Medical Interventions; New Hope, Pennsylvania) stapler is utilized to create the gastrojejunostomy. After the procedure, the staple lines were examined and noted to be intact.

Before a pure NOTES gastric bypass or sleeve gastrectomy becomes a reality in a live, morbidly obese human, there are important challenges that need to be overcome. First, since the stomach cannot be the only orifice utilized, instrumentation that can maneuver over the pelvic rim up and then straight to the angle of His needs to be developed. It is difficult for the stapler to be placed through either the rectum or the vagina, up over the pelvic rim, and then back down to be in the same plane of the stomach. It needs to be flexible to maneuver to the upper abdomen but has to be rigid to have control for proper placement. Second, a reliable, FDA-approved NOTES device needs to be available for hemostasis. Third, a reliable, FDA-approved NOTES device needs to be easily available for suturing. While it is possible to utilize current laparoscopic equipment via the rectum and/or vagina, the design of the current instrumentation is not ideal. Fourth, closure of the chosen pelvic organ of entry needs to be perfected. A leak of a vaginotomy may become a major cause of complications in a morbidly obese patient. Finally, external access to the pelvic organs may be cumbersome and not practical in all patients.

Laparoscopic surgery initiated a revolution in the treatment of morbid obesity. Even more minimally invasive procedures, such as natural orifice bariatric surgery, offer the potential of fueling another revolution. At this time, however, primary endoluminal bariatric procedures are still in their infancy. In addition, the exact role of these procedures needs to be defined. Whether these are considered definite procedures or just bridging procedures to a more definite operation is still in question. Furthermore, it is not known what the effect of these procedures will have on future bariatric procedures. If the endoluminal bariatric procedure fails, subsequent laparoscopic bariatric procedures may be more difficult to perform.

NOTES bariatric procedures are still experimental. No study of pure NOTES bariatric procedures in live humans has been published. While there are many groups investigating these procedures in animal and/or cadaver models, many issues, such as safety and efficacy, still need to be resolved. While feasibility is being established, the main question remains whether NOTES bariatric procedures offer any advantages over current laparoscopic bariatric procedures.
Endoluminal revisional bariatric procedures are being performed today. Considering the current available alternatives (no surgery, laparoscopic surgery, or open surgery), their efficacy, and their potential complications, endoluminal treatments have a definite role, even today, when encountering a patient after gastric bypass with weight regain or insufficient weight loss. Intuitively, it seems that the full-thickness techniques that offer apposition of tissue offer more durable and consistent results. Unfortunately, long-term data do not exist at this time. Before performing these procedures, the surgeon must discuss the lack of long-term data with his or her patients.

The field of bariatric surgery is continually evolving. Endoluminal treatments are here in the present. Potential hybrid and pure NOTES procedures are on the horizon. It is imperative that bariatric surgeons gain the skill and experience in flexible endoscopy so that they may offer the patients various potential alternative treatments in the future. While long-term data are still lacking, natural orifice bariatric surgery has a real potential of changing the treatment of our morbidly obese patients.

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