Metabolic surgery: Procedures vary internationally

Obesity and diabetes are global epidemics, affecting millions of lives. Metabolic surgery, once primarily a U.S. procedure, has developed in most countries to treat the growing number of individuals afflicted with adiposity-based chronic diseases. In the U.S., exacting standards for acceptance of procedures established by the professional surgical associations along with stringent governmental and legal regulation of devices impose layers of restriction on development and testing of new operations. However, other countries have unique genetic and cultural differences that justify the modification of standard U.S. operations. For example, the Asian population is at a higher risk for development of diabetes at a lower body mass index than their American counterparts; at the same time, they have the added burden of a higher incidence of gastric cancer, rendering screening of the gastric remnant in a gastric bypass impractical. Thus, metabolic procedures must be devised to lessen this potential risk while providing a greater metabolic effect without excessive weight loss. Procedures must also be affordable and require less maintenance in countries where no public financial support exists. Less stringent procedural standards allow for innovations in surgical technique that benefit disease treatment and our understanding of the disease itself. All countries must address the ethics of permitting novel, yet potentially lifesaving, interventions. Since no single procedure is effective in all patients, the availability of a multitude of bariatric metabolic procedures from around the world enables surgeons to tailor treatment to the needs of the patient.

Background

Metabolic surgery involves operations and procedures to treat metabolic diseases, particularly type 2 diabetes mellitus (T2DM). These procedures entail operating on normal organs to effect changes that treat medical ailments. The most common metabolic operations at this time are bariatric procedures.¹

In the U.S., surgeons perform only a handful of operations in the armamentarium of bariatric metabolic surgery, some of which incorporate U.S. Food and Drug Administration (FDA)-approved implantable devices. The accepted bariatric procedures are Roux-en-Y gastric bypass (RYGB) (short limb, banded, distal, and long limb); sleeve gastrectomy (SG); biliopancreatic diversion with duodenal switch (BPD-DS); laparoscopic adjustable gastric banding (LAGB); gastric balloon implantation, vagal blockade (also known as vBloc); and percutaneous endoscopic gastrostomy tube for aspiration (also known as AspireAssist). These U.S.-approved operations have been discussed in other articles published in this series in previous issues of the Bulletin.

Internationally, however, many additional bariatric metabolic operations and devices are in use. This gap in offering these services and devices in the U.S. is attributable to the stringent constraints and lengthy trial and approval process of the FDA, as well as the high standards for acceptance set by professional surgical associations. These bodies pursue protection of patients vigorously, and a legal atmosphere surrounding medicine adds another layer of restriction to the use of new procedures and devices.

Other nations grant more freedom to perform new operations and procedures. The surgeon-patient relationship is less regulated and the legal atmosphere is more relaxed outside of the U.S., Canada, Australia, and the European Union (EU). Publication of outcomes determines acceptability of operations and procedures in the U.S., but in most of the rest of the world, peer-reviewed outcome publications are less frequently needed for surgical procedure acceptance. The U.S., Canada, Australia, and the EU make a clear delineation between experimental, investigational, and accepted operations and procedures, whereas in much of the rest of the world, these categories are less clearly defined. Economic and social restrictions also determine the use of operations and procedures that are not used in the U.S. Understanding some of the mechanisms of effectiveness of bariatric metabolic operations and the role of gut hormones has opened the field to the design of novel operations that take advantage of these mechanisms. This article focuses on metabolic operations that are commonly used internationally but not in the U.S.

OAGB and BGBP

One-anastomosis gastric bypass (OAGB), commonly called the mini-gastric bypass (MGB), is the third most common operation performed worldwide after SG and the short-limb gastric bypass (GBP). It is the second most performed operation in Spain, Italy, France, and India. Robert Rutledge, MD, FACS, first described the procedure in the U.S. in 1997, but the operation fell into disrepute and was poorly accepted because of a perceived high incidence of bile reflux and concern that it was associated with a high probability of Barrett’s esophagus and malignancy.^2,3 The American Society for Metabolic and Bariatric Surgery (ASMBS) has not approved OAGB/MGB for lack of good clinical studies on bile reflux effects and scant long-term studies. Internationally, modifications have been made in the operation (for example, omega-loop GB, single-anastomosis GB, one-anastomosis GB), and the operation is now commonly performed in Europe, the Middle East, and Asia-Pacific countries.^4-8

OAGB/MGB entails creating a long tubular pouch made on the lesser curvature of the stomach (see Figure 1). The pouch is connected to a loop of jejunum at 150 to 250 cm from the ligament of Treitz using a wide, nonrestrictive anastomosis. This operation is relatively easy to perform because only one anastomosis is made at the level of the antrum of the stomach. The large Petersen’s defect is rarely closed in this operation, which is a source of concern for many surgeons. Weight loss is more rapid and slightly greater than with the standard RYGB, mostly because of a longer biliopancreatic limb. Studies comparing standard RYGB with OAGB/MGB achieve similar results. Use of a longer biliopancreatic limb yields a greater positive metabolic effect on T2DM and hyperlipidemia.^7-9

Options for revision with the OAGB/MGB, if indicated, and a lower incidence of internal hernias have been observed. (Although internal hernias after laparoscopic RYGB took more than a decade to become a real clinical problem, it has yet to be seen whether the same complication will develop with OAGB/MGB.) However, OAGB/MGB has been associated with bile reflux (as previously stated), marginal ulcerations, nutrient deficiencies, protein malnutrition, liver failure, and possible multiple organ failures. Advocates of this operation claim these concerns can be addressed by customizing the biliopancreatic limb to the weight and nutritional habits (vegetarian/nonvegetarian) of the patient.¹⁰ This suggests that the operation needs to be further refined before advocating its widespread use. Most long-term studies have not reported detailed nutritional examinations.

Some surgeons place a nonadjustable ring around the proximal gastric pouch in patients with a high BMI to enhance OAGB/MGB weight loss and weight-loss maintenance (see Figure 2).¹¹ The surgeons claim that placement of the ring addresses late weight regain and bile reflux. No long-term reports of the effectiveness of this modification have been published. The use of the loop gastroenterostomy in the OAGB/MGB has opened a new era of single-anastomotic operations in metabolic surgery.

Sleeved GB

The diverted OAGB/MGB, or sleeved GB (SGB), is a modified RYGB that evolved from converting an OAGB/MGB to an RYGB to address complications of bile reflux following OAGB/MGB. The afferent limb of the loop of the OAGB/MGB is transected just proximal to the gastroenterostomy and anastomosed to an 80-cm RYGB alimentary limb (see Figure 3). Some surgeons use this operation as a primary procedure because the weight-loss outcome is similar to that of the OAGB/MGB, without the concern of bile reflux. It is an easier GBP to perform because the small bowel does not have to be brought up close to the gastroesophageal junction, and thus, less tension is placed on the anastomosis. However, this modification may lead to a higher incidence of marginal ulceration as a result of the increased acid load from the larger gastric pouch.

BGBP

Like the OAGB/MGB, the banded gastric bypass (BGBP) operation was first described and used in the U.S. by the late John Linner, MD, FACS. Initial reports showed a high incidence of ring erosion, as Linner placed the band at the gastroenterostomy. Mathias A.L. Fobi, MD, FACS, FACN, FICS, a co-author of this article, modified the operation in 1986, placing the ring/band around the pouch, 2 cm above the gastroenterostomy, and reported a lower incidence of band erosion and better weight loss and weight-loss maintenance. The operation is essentially a standard RYGB with a 6–8 cm tubular pouch on the lesser curvature with a nonadjustable ring/band loosely placed 3–5 cm below the gastroesophageal junction and at least 2 cm above the gastroenterostomy (see Figure 4).^12-15 Unlike the standard GBP, the gastroenterostomy created is 2.0–2.5 cm instead of about 1.5 cm. The gastroenterostomy is formed using a Roux-en-Y with an 80-cm biliopancreatic limb and 80-cm alimentary limb. The location at which the ring is placed acts as the functional stoma of the operation. It is hypothesized that the ring enhances the restrictive mechanism of the gastric bypass operation, providing the effect of satiety when stretching of the gastroesophageal junction stimulates the vagus to relay a sense of fullness. This stabilized restricting outlet also reinforces behavior modification by requiring the patient to eat slowly and chew foods well before swallowing, even years after operation.

The BGBP is reported to provide more weight loss and better weight-loss maintenance in the intermediate to long term as compared to the regular RYGB.¹⁶ In a systematic review by O’Brien and colleagues, the weight loss and maintenance outcome are equal to that seen after the BPD-DS without the risks of protein-caloric malnutrition, intractable diarrhea, and foul odor.¹⁷ The reported complications after the BGBP include ring erosion, kinking at the point where the ring is placed, gastroesophageal reflux disease, and solid food intolerance requiring ring removal in some patients.¹⁸ There are many prefabricated, sterilized, and standardized ring devices in the international market for banding the GBP, but the FDA has approved none, which limits the use of this operation in the U.S. The few surgeons who band the GBP in the U.S. either use a surgeon-fashioned ring or use the adjustable gastric band off label.^19,20 The incidence of band-related complications is less than 10 percent. Band erosion, reported in less than 2 percent of patients, is treated with outpatient endoscopic removal, converting a BGBP to a standard RYGB. In most cases, a band or ring removal results in some weight regain.

BSG

The banded sleeve gastrectomy (BSG) is an SG that is banded with a nonadjustable ring placed loosely around the proximal sleeve 3–5 cm from the gastroesophageal junction (see Figure 5). This operation is based on the experience of banding the GBP. The sleeve in the BSG is less narrow than the one used in the standalone SG because the ring serves as the restrictive mechanism, which creates a lower likelihood of stricture and leak at the gastroesophageal junction. Reports indicate that banding the sleeve enhances weight loss and weight-loss maintenance, just as with the RYGB in the short term.^21,22 Better diabetes control has been reported with the BSG in the short term, related to the enhanced weight loss. Complications reported with the BSG include ring erosion, kinking at the site of the ring, and solid food intolerance. As with the BGBP, complications of band erosion are treated with outpatient endoscopic band removal. Solid food intolerance is treated by either band/ring removal or revision of the operation to an RYGB. Concerns about increased reflux when banding the sleeve are unconfirmed. As with the BGBP, the absence of an FDA-approved ring device has limited the use of this operation in the U.S.

SG with DJB

The SG with duodenojejunal bypass (DJB) entails an SG with a Roux-en-Y duodenojejunostomy (see Figure 6). The bypass of the duodenojejunal axis enhances the metabolic effects of the SG.^23,24 This operation is popular in countries with a high incidence of gastric cancer. In these countries, GB is not advised because the regular bypassed stomach is not readily accessible to endoscopic evaluation. The outcome of this operation is better than with the SG, and about the same as with RYGB. In addition, incidents of dumping and marginal ulceration are reportedly less common. The incidence of nutrient deficiency is the same as with an RYGB. SG with a loop duodeno-jejunostomy is a variant of the SG with DJB using a single anastomosis as in the OAGB/MGB (see Figure 7).²⁵ The outcome of this variant is the same as with the SG with DJB. Surgically, the SG with loop DJB is a simpler operation that places less tension on the alimentary limb. These operations are mostly performed in Japan, China, Taiwan, and Southeast Asia.

SADI-SG and SADI

Single-anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-SG) and its variant, sleeve gastrectomy with single-anastomosis duodeno-iliostomy (SADI), is akin to the BPD-DS. It is an SG with a duodeno-ileostomy at a point 250 cm from the ileocecal junction (see Figure 8). First described by Sanchez-Pernaute and colleagues, and popularized by Torres, this operation is reportedly almost as effective as the BPD-DS in the short term, but with a lower incidence of diarrhea and protein malnutrition.²⁶ The diabetic resolution is similar to that reported for BPD-DS, which is the highest resolution reported for any bariatric operation, including OAGB/MGB. This operation is increasing in popularity in the U.S. and is performed under institutional review board (IRB) protocol in many institutions, including academic centers. Use of the DS and its variants has increased by 50 percent in the last two years. As of the time of this submission, most surgeons make the duodeno-ileostomy at a point 300 cm from the ileocecal junction.

A variant of this operation, stomach intestinal pylorus-sparing surgery (SIPS), with a 300-cm limb instead of the 250-cm limb as in the SADI (but with a smaller-diameter gastrectomy [bougie size near 40 Fr, as opposed to 50 Fr in SADI]), is being used in U.S. clinical trials.²⁷ Both operations are used primarily as a second-stage operation for SG when more weight loss or more T2DM control is indicated, or when the patient regains weight.

SG with transit bipartition

This operation entails an SG with a Roux-en-Y gastroileostomy from the gastric antrum at a point 250 cm from the ileocecal junction. Food ingested flows through both the gastroiliostomy and the pylorus into the duodenum and proximal jejunum (see Figure 9).^28,29 This operation is designed to use the various mechanisms that we know are responsible for effective bariatric metabolic outcomes. The SG decreases ghrelin secretion by removing most of the gastric parietal mass. The flow of most food through the gastroiliostomy instead of through the pylorus minimizes foregut stimulation and enhances hindgut stimulation. Most importantly, nutrient deficiencies, usually a result of bypass of the duodeno-jejunal axis, are obviated or minimized. Minimal dumping occurs, and the incidence of diarrhea is lessened. The duodenum and papilla are accessible endoscopically. This operation is amenable to easy revision and reversal, as indicated.^29,30

SASI

The single-anastomosis sleeve with ileal bypass (SASI) is an SG with a loop transit bipartition instead of the Roux-en-Y gastroileostomy at a point 300 cm from the ileocecal junction. This operation was first described by Santoro in Chile as an SG with a bipartition (see Figure 9). Professor Tarek Mahdy, from the United Arab Emirates, has popularized this modification. Food that is ingested flows through both the gastroiliostomy and the pylorus into the duodenum and proximal jejunum (see Figure 10).³⁰ This operation uses the various mechanisms known to result in an effective bariatric metabolic operation. The SG decreases ghrelin secretion by removing most of the gastric parietal mass. The flow of most food through the gastroiliostomy instead of through the pylorus minimizes foregut stimulation and enhances hindgut stimulation. Most importantly, nutrient deficiencies usually associated with bypass of the duodenojejunal axis are obviated or minimized. Dumping is minimal, and the incidence of diarrhea is less. The duodenum and papilla are accessible endoscopically. This operation is amenable to easy revision and reversal, as indicated. The outcome from this operation compares favorably with the BPD-DS without the nutrient deficiencies and protein caloric malnutrition. Few long-term reports have been published on this operation. The procedure needs to be compared clinically with others and validated by additional surgical groups, especially with respect to ulceration and the patency of the anastomosis in the long term.

SG with enteral bypass

These operations entail an SG with a jejunojejunostomy using one of the following: 100 cm of jejunum anastomosed to the jejunum with 200 cm of bypassed jejunum from the ligament of Treitz (see Figure 11); a jejunoileostomy akin to the jejunoileal bypass with 100 cm of jejunum anastomosed to 200 cm of ileum (see Figure 12); or a side-to-side jejunoileal anastomosis 100 cm from the ligament of Treitz to the ileum at 200 cm from the ileocecal junction^31,32 (see Figure 13). These operations use the known mechanisms of restriction and ghrelin secretion reduction resulting from SG and the hindgut mechanism of ileal stimulation. The weight-loss effect and metabolic resolution of T2DM with these operations is better than with the SG and similar to what is reported with the short-limb GB, although internal hernias are a major concern over the long term. These operations are technically simpler to perform than the short-limb GB. A question that remains is the incidence of bypass enteritis and subsequent liver failure after these operations.

DJB

The DJB is strictly a metabolic operation to control T2DM. It entails a transection of the duodenum beyond the pylorus with a duodeno-jejunostomy 100–200 cm from the ligament of Treitz (see Figure 14). Minimal weight loss is associated with this operation. The procedure is based on the foregut hypothesis of control of T2DM by bypassing the duodenojejunal axis. Rubino demonstrated the effectiveness of this procedure in controlling T2DM in rats, and Cohen reported use of the operation in humans with T2DM who are not obese.^33,34 It is a common operation in the Asia-Pacific region, where T2DM is relatively common. In Brazil, surgeons have demonstrated that if the procedure is not combined with an SG, the metabolic results are insufficient. Hence, many surgeons no longer perform this operation.

II and II-SG

Ileal interposition (II) was described initially as a metabolic operation for T2DM because stimulation of the ileum by ingested foods results in release of glucagon-like peptide 1 (GLP-1), which enhances insulin sensitivity and control of T2DM. The original concept was proposed by Mason.³⁵ Gagner and his colleagues performed original animal research with this operation and published outcomes of the first patients.^36-38 De Paula popularized II operations for treatment of T2DM or for T2DM treatment in morbidly obese patients by adding the SG to the II (see Figure 15A–B).^39-41 The reported outcomes for treatment of T2DM are similar to those reported with the standard GBP; however, the operations are technically demanding and entail multiple anastomoses. Although internal hernias (due to the multiple defects created) are routinely closed, their high incidence from potential leaks from several gastrointestinal anastomoses, and the prolonged operating times associated with internal hernias, have been the source of concern. Reported prospective evaluations of both operations are unavailable, though they are used internationally.

GP and BGP

Gastric plication (GP), first reported in the U.S. in the 1970s and repopularized in Iran by Talebpour in 1999, is an SG that is formed by plicating and/or infolding the greater curvature of the stomach vertically with nonabsorbable sutures after the omentum has been transected (see Figure 16A), as in the regular SG. No transection or resection of the bowel is involved in this operation.^42-44 Because no staples are used, it is less expensive and can be performed in parts of the world where availability or affordability of staples is a problem. This operation results in anatomy similar to the SG and the laparoscopic adjustable banding operations. The main proponents of this operation claim that it saves costs as a result of not using stapling devices and the complete reversibility of the operation. We now know from multiple revision reports of GP to SG or GB that its reversibility is questionable and is no longer the main reason that this operation is performed. It requires the same amount of time as an SG and carries essentially the same risks (perforation, bleeding, and portal vein thrombosis). Banding the GP operation is akin to banding the GBP or SG (see Figure 16B).⁴⁵ The band used with a SG is an adjustable band. Banding the plication is based on the experience with the BGB where the banded pouch enhances weight loss and weight-loss maintenance. The results are better than with only GP but less than with the surgically performed SG.

Endobarrier

The Endobarrier is an endoscopic device used internationally but not in the U.S. (see Figure 17), although the manufacturer is located near Boston, MA.^46-48 The procedure entails placing an endoluminal polymer sleeve of more than 30 cm, anchored with a metallic stent in the duodenum that allows food to bypass the duodeno-jejunal axis, as in the DJB or GB. It is strictly a metabolic procedure for treatment of T2DM. It uses the known foregut mechanism of bypassing the duodenojejunal axis, thus minimizing insulin resistance and enhancing GLP-1 secretion and controlling T2DM. Clinical trials in the U.S. are ongoing. The main concerns have been liver abscesses from the spikes of the metallic stent anchored in the duodenum and perforating it, as well as gastrointestinal bleeding. The device is being used internationally, with T2DM resolution reported as 60 to 74 percent at one to two years of follow-up. It remains to be seen whether the Endobarrier will be a good device to indicate whether surgical DJB will affect resolution of T2DM in a nonobese patient, as gastric balloons achieve similar results with fewer complications.

Conclusion

More operations, procedures, and devices for bariatric metabolic surgery are available internationally than in the U.S. because other countries have fewer regulatory and professional roadblocks to the use of new treatments. The plethora of available procedures is accompanied by concerns regarding safety and documentation. These innovations often lead to paradigm shifts in our understanding of both the physiology of our interventions and the disease process itself. Governmental oversight analogous to the FDA may not exist in some countries; however, ethical standards exist in all countries, although they differ from one another. For example, the Declaration of Helsinki, now in its seventh revision, is the most respected set of ethical principles used to guide medical researchers in protecting patients enrolled in biomedical trials. The declaration opposes the ethics of placebo-controlled trials as purposefully withholding treatment from some individuals.⁴⁹ However, countries such as the U.S., Canada, Australia, and Japan use the Declaration of Helsinki, as well as other ethical guides, and still use placebo-controlled trials.⁵⁰

Acknowledgments

This work was supported by the ACS. The authors declare that they have no relevant conflict of interest. Dr. Fobi declares that he is founding president and a shareholder of Bariatec Corporation (manufacturer of the ring devices). Dr. Fobi also discloses that he was a recipient of the ring banded gastric bypass in 2011 to control diabetes.

Dr. Gagner declares speaker honoraria from Ethicon, Medtronic, Valeant, and Gore; and stock options from Transenterix.

We are grateful to the ACS for their generous sponsorship of the Metabolic Surgery Symposium and associated journal publication development. We thank Jane N. Buchwald, chief scientific research writer, Medwrite Medical Communications, Maiden Rock, WI, for manuscript editing and publication coordination. And we thank Patrick Beebe and Donna Coulombe, ACS Executive Services, for their expert organization of the Metabolic Surgery Symposium.

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