Obesity is an epidemic worldwide and bariatric surgery is the best treatment for patients who have morbid obesity. Sleeve Gastrectomy (SG) is the most frequently performed bariatric procedure, surpassing Roux-en-Y Gastric Bypass (RYGB) in 2013 [1] [2] .

Although SG carries the advantages of preserving the continuity of the entire gastrointestinal tract, reducing nutritional issues, it’s alluded as a refluxogenic operation, leading to high indices of gastroesophageal reflux disease (GERD) [3] [4] [5] . The reduction in gastric complacency is one important factor related to GERD after SG. The pylorus can influence in GERD development, as it causes an intermittent barrier to free gastric flow, contributing to the increased gastric chamber pressure [6] .

Concerning RYGB, it represents the second most frequently performed bariatric surgery in the world [1] . This technique has shown good long-term results, regarding weight loss and comorbidities control [7] . However, many authors have demonstrated high indices of failure, showing weight regain in superobese patients [8] . In such situation a revisional surgery is a plausible treatment alternative. There are many surgical options, but the most effective is conversion to BPD-DS or SADI-S [9] . These conversions are technically cumbersome, with relatively high incidences of complications, mainly related to the gastro-gastric anastomosis (GGA), a step of this operation [10] [11] . Again, the pyloric sphincter, sometimes spastic, could contribute to increase intragastric pressure, which could lead to gastro-gastric fistula occurrence.

In this article, two cases of bariatric surgeries are reported, one primary (SG) and other, revisional (conversion from RYGB to SADI-S, due to weight regain). In both cases, as a surgical tactic, the pyloric region was dissected, with terminal pyloric arterial branches ligation, making it possible to encircle the pylorus with a tape, for field exposure purposes. It was observed, in the postoperative endoscopy of both cases, a complete and permanent pylorus relaxation, lasting until one-year follow-up. This finding can represent the effect of pyloric sympathectomy which is associated with pyloric blood vessels ligation. Opening the pylorus could diminish intragastric pressure and represent an important surgical step to reduce GERD related to SG and GGA fistulas, related to RYGB conversion to SADI-S. To confirm this hypothesis, further investigation is necessary.

The patients signed a Free and Informed Consent Form (FICF) and were informed about the procedure they would be undergoing, which would be a Sleeve Gastrectomy and a RYGB conversion to SADI-S. All their queries about the procedures were answered, in the presence of a companion. It was explained about possible intra and postoperative complications, as well as the possibility of changes in surgical planning, in case of intraoperative unexpected findings or intercurrences. An informed consent was signed by the patients, giving permission to use these cases details and images of the surgeries by the surgeon, for scientific purposes, preserving their identities. All the human data was performed, in accordance with the Declaration of Helsinki.

In this case report we present a tactical maneuver, that is a pylorus dissection through its vessels and adherences ligation, followed by a passage of a tape, used to pull the sphincter to get an adequate surgical field exposure. In the first case it was used in order to facilitate the first antral staple shot, in a Sleeve Gastrectomy. In the second, the purpose was to improve the retro duodenal visualization for duodenal transection, in a RYGB conversion to SADI-S. In 1-year endoscopic postoperative evaluation it was found a wide open pylorus, in both cases.

Both patients were submitted to endoscopic evaluations in first month and first year postoperative period. No alterations were found in early examinations. Bellow, the findings of 1-year evaluation will be reported.

In this current study, it is reported a pyloric relaxation, endoscopically observed in two bariatric cases, one of them a primary SG and the other one, a revisional surgery (RYGB conversion to SADI-S). In both cases, the sphincter atony was kept until 1-year endoscopic postoperative evaluation. This can represent a novel neuromodulation on the pylorus motility, which leads to a wide and permanently open pylorus. This functional response can be explained by pyloric synchronous sympathetic nerves transection, that occurred during peripyloric arterial terminal branches ligation, coming from right gastric, gastroduodenal and right gastroepiploic arteries, considering that the sympathetic gastrointestinal nerves wrap the corresponding gastrointestinal arteries [12] [13] . Such devascularization was required for pyloric traction with a tape to get a better surgical field exposure. In SG case, this maneuver facilitated the first antral stapling, while in the revisional one, it exposed better de duodenum, for its septation.

Sleeve gastrectomy has proved to be an effective bariatric procedure [14] . There are some potential advantages of doing this operation, other than achieving good weight loss results. The absence of gastrointestinal exclusions is of paramount importance in the presence of gastrointestinal cancer family history, gastric polyposis, gastrointestinal stromal tumors, intractable H. pylori infection, inflammatory bowel diseases and others [15] [16] . However, the high incidence of gastroesophageal reflux disease associated with this operation is a problem [17] [18] [19] . One factor related to this is the elevated intragastric pressure, due to gastric complacency reduction, that follows the subtotal longitudinal gastric wall resection [6] . Besides, the pyloric sphincter, which normally regulates gastric emptying, can represent a barrier to this process, after a sleeve gastrectomy, increasing even more the intragastric pressure. Some authors have demonstrated a reduction of GERD incidence related to SG, by adding a gastrointestinal anastomosis to decompress the gastric chamber [20] [21] [22] . Back in the 70s and 80s, some studies showed the decompressing effect of pyloroplasty and pyloromyotomy on the stomach, improving gastric emptying [23] [24] . A functionally open pylorus, derived from a pyloric sympathectomy, alluded in this current case report, could be another way of alleviating the high intragastric pressure related to sleeve gastrectomy technique, without the inherent risks associated with pyloroplasty/pyloromyotomy. The relaxed pylorus would achieve expedited gastric emptying, which could help to reduce gastroesophageal reflux disease incidence [25] . These same mechanisms could also decrease acute gastric fistulas, considering there is no obstructive factor proximal to the pylorus [26] [27] . Accelerated gastric emptying is a desired effect in sleeve gastrectomy, considering this could contribute to increased incretin stimuli [28] . A functionally open pylorus could contribute to the expedited gastric emptying.

Conversions of RYGB to other techniques, due to weight regain, are not uncommon. When this operation involves a reinsertion of the excluded stomach in the gastrointestinal tract, a spastic pylorus is a possibility. This can be related to vagus nerve injury, during the primary operation, hindering gastric emptying and creating a high-pressure gastric chamber [29] . Such a situation could lead to an increased risk of gastro-gastric anastomosis fistula, which incidence is relatively high in these conversions [30] [31] . Therefore, a permanent or even temporarily pyloric relaxation might be protective against this complication. Adding a pyloroplasty to lower intragastric pressure in these conversions could add risks to the procedure, considering the proximity with the duodenum-ileal anastomosis step of the SADI-S procedure. Achieving pyloric relaxation through pylorus sympathectomy avoid these risks.

Regarding the safety of pyloric devascularization, the gastroduodenal transition has a good submucosal arterial interconnection, which makes the proposed sympathectomy a safe maneuver, in terms of blood supply to this area [32] .

The limitations of this case report relate to the short-term evaluation of the functional effects on the pylorus (relaxation) brought by pyloric sympathectomy and the absence of manometric pyloric evaluation. It was an observational finding, during the 1-year postoperative endoscopic evaluation in two cases. This warrants controlled studies for more robust inferences.

Proof of this finding would be of great applicability, not restricted to primary or revisional bariatric surgeries, but in other surgical fields, in which a relaxed pylorus would help in reducing acute and chronic complications, such as in esophageal resections, primary or redo fundoplication associated with gastric stasis, primary pyloric hypertonia and others.

We report two cases of bariatric surgeries, one of them revisional, with an observational novel functional pyloric response. A one-year lasting pylorus atony was endoscopically observed, probable due to its terminal arterial branches ligation, which implied a simultaneous corresponding sympathetic nerves sectioning. This probable pyloric neuromodulation has the potential to be beneficial in primary sleeve gastrectomy and in revisional bariatric surgeries, considering the consequent intragastric pressure reduction. This maneuver could be protective against acute gastric pouch and/or gastro-gastric anastomosis fistulas and could avoid long-term GERD development. Further studies are necessary to confirm this hypothesis.

Thank Bariatric Channel ( https://www.bariatricchannel.com/ ) as a research support.