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Treatments

The Banded Gastric Bypass

(For the treatment of Morbid Obesity)

The Banded Gastric Bypass

The banded gastric bypass (BGBP) operation is a gastric bypass procedure, in which a Ring or Band is placed around the pouch to provide a fixed outlet from the gastric bypass pouch.

The banded gastric bypass operation requires the creation of a gastric pouch 5-7 cm long 20-30cc in size by vertically transecting the stomach just distal to the gastro-esophageal junction. A gastro-jejunostomy anastomosis ~2cm in width is formed to provide gastro intestinal continuity. A ring is placed around the gastric pouch approximately 2 cm above the gastro-enterostomy site to provide a stabilized outlet.

Surgical Treatment of Obesity

The obesity epidemic continues to persist despite global educational efforts and treatment with diet, exercise, and pharmaceuticals. Morbid obesity is closely associated with co-morbid conditions experienced in different facets of life. Medical conditions associated with morbid obesity include diabetes, sleep apnea, hypertension, arthritis, GERD and pseudotumor cerebri. In addition to the aforementioned co-morbidities, there are a host of other negative collateral effects such as social degradation, physical limitations, detrimental economic implications (most often due to limited employment opportunities, higher cost of living, higher cost of medical care), and psychological ramifications (e.g. low self-esteem and depression) ramifications that aggregate in the form of a. overall diminished quality of life for morbidly obese individuals. To date, metabolic/bariatric surgery remains the most effective intervention for morbid obesity with documented greater than 50% excess weight loss (EWL) maintained beyond 10 years.

Evolution of the Banded Gastric Bypass Procedure.

In 1967, the primary gastric bypass with a loop gastro-jejunostomy was introduced by Mason and Ito (Fig.1a) to treat morbid obesity based on the observation that patients who had subtotal gastrectomy for ulcer disease, which leaves a small gastric pouch, lost weight and maintained their weight loss in the long term [1]. In light of this discovery, the ulcer operation was modified to a gastric bypass operation for weight loss. The gastric bypass operation was further modified to a Roux-en-Y Gastric bypass, (RYGBP) (Fig.1b), with a pouch 20- 30 cc in size and a 1-2 cm diameter pouch outlet as it became apparent the pouch and outlet size was important to maximize weight loss [2]. This modified gastric bypass became the standard for Bariatric operation, and it is widely used today.

The RYGBP effectiveness, at that time, was perceived to be due to the small size of the pouch. This perception and the morbidity and mortality rates at that time from the gastric bypass operation prompted Mason to introduce a simpler and safer gastroplasty operation, the horizontal gastroplasty (Fig.1c), with a small pouch and a 1-2cm stoma and without bypassing any part of the gastro-intestinal tract. The initial weight loss with this operation was comparable to that of the RYGBP; however, with follow-up beyond one year, there was a high failure rate with partial or complete weight regain in some cases. The failure of the horizontal gastroplasty was determined to be attributable to the dilation of the pouch outlet. In 1980, Mason modified the gastroplasty operation to a vertical banded gastroplasty (VBG) (Fig.1d) with a surgeon-fashioned band placed around the pouch to stabilize the outlet [3]. This prevented pouch and stoma dilation and greatly enhanced the weight loss and weight loss maintenance after the VBG operation. In 1991, the NIH endorsed the RYGBP and the VBG as operations that provided viable long-term treatment of obesity [4].

  • gastric bypass with loop
  • RYGBP
  • horizontal gastroplasty
  • VGB

Fig 1. (a) gastric bypass with loop; (b) RYGBP; (c) horizontal gastroplasty; (d) VGB

Beyond four years of the modified Roux-en-Y gastric bypass operation, surgeons started observing weight regain and failure of the gastric bypass in a subset of patient. This failure was determined to be mainly due to pouch and outlet dilation of the gastric bypass operation. In 1984, based on the observation of banding the pouch outlet in the VBG, Linner started placing a band around the gastro-jejunal anastomosis to stabilize the pouch outlet (Fig.2a) [5]. However, placement of a band at the anastomotic site resulted in a high rate of migration. Therefore, in 1986, Fobi modified the method of banding the gastric bypass by placing the band around the gastric pouch at least 2cm proximal to the anastomosis (Fig. 2b). This procedure is referred to as the banded gastric bypass (BGBP) [6]. Fobi reported better weight loss, weight loss maintenance and a 2% rate of band migration with the BGBP, which has been corroborated by multiple reports of long-term clinical investigations [7-12].

  • Gastric bypass with band at the anastomosis
  • BGBP

Fig 2. (a) Gastric bypass with band at the anastomosis; (b) BGBP

Weight Loss Mechanisms of the Gastric Bypass

The Banded Gastric Bypass (GBP) has proved to be the most consistently successful treatment for obesity for the greatest number of patients. The mechanisms of action operating in the banded gastric bypass include:

  • Neural Stimulation of gastro-esophageal (GE) junction (Full Sense) – When patients fill the pouch with food to the point that the proximal GE junction stretches and the nerves are stimulated, they will feel a sense of fullness;
  • Restriction – The small size of surgically created pouch and pouch outlet restricts the amount of food a patient can ingest before distending the GE junction. The stabilized outlet slows the transit of food out of the pouch, thus prolonging the feeling of satiation;
  • Malabsorption – Selective mal absorption results from the bypassing of the gastro-duodenal axis. The delayed mixture of the food with the pancreatic enzymes and bile acids, due to bypassing the gastro-duodenal axis, results in decreased digestion and selective mal absorption of fats;
  • Ghrelin Effect – The Ghrelin hormone is produced in the stomach and stimulates hunger in the brain. Bypassing the stomach results in decreased secretion of Ghrelin hormone resulting in anorexia with diminished desire to take in calories;
  • Neurotensisn (Dumping Syndrome) – Direct transit of food from the pouch into the small bowel results in mild dumping, thus decreasing the patient’s desire for intake of calorically dense foods;
  • Enterokinin Effect – Secretion of incretins, GLP-1, GIP and PYY, from the foregut and hindgut alters taste and desired food intake, resulting in decreased caloric intake;
  • Gut Micro Biota – Change in the bacterial flora of the gastro-intestinal tract after the banded gastric bypass alters taste and the desire for food, resulting in decreased caloric intake; and
  • Patient Compliance – Patients must be motivated and willing to adjust their dietary habits, must keep in contact with their physician, and must follow physician recommendations [12-14].

The surgically created pouch and pouch outlet size are important to the effectiveness of the restriction and full sense mechanisms of the banded gastric bypass procedure If the restrictive mechanism is not moderately maintained, a subset of patients will experience complications associated with pouch outlet dilation, including inadequate weight loss, weight regain, return of their co-morbid conditions, other complications [6, 15-16] and very frequently revisional surgeries with the associated consequences.

Why does the Gastric Bypass Fail?

Pouch outlet dilation is a part of the gastric anatomy’s natural history after the gastric bypass procedure [16-18]. However, pouch outlet dilation, at the gastro-jejunal anastomosis to a diameter beyond 2 – 3 cm may defeat the restriction mechanism, since ingested food will pass freely through the pouch and pouch outlet, directly into the bowel [6, 16]. Pouch outlet dilation result in a loss of the restrictive mechanism of the gastric bypass procedure and results in the formation of a gastric food reservoir that is comprised of the surgically created pouch, pouch outlet, and proximal small bowel [6, 15, 19]. This dilation allows patients to ingest more food before achieving the full sense [17, 20]. Loss of restriction at the pouch outlet is a significant anatomic factor leading to adverse