Per-Oral Pyloromyotomy (POP) for Medically Refractory Post-Surgical Gastroparesis

Initial experience and outcomes of per oral pyloromyotomy for the treatment of refractory gastroparesis

BACKGROUND

Gastroparesis can be a debilitating disease process for which durable treatment options are lacking. While dietary changes and pharmacotherapy have some efficacy, symptoms frequently recur and some patients progress to needing supplemental enteral feeding access. Per oral pyloromyotomy (POP) has been shown to be a durable minimally invasive treatment option for refractory gastroparesis with a low side effect profile, and therefore has been performed at this institution for the past 6 years.

METHODS

This was a retrospective case series of all patients who underwent a POP at a single institution over a 6-year period (2018-2023). Patient demographics, preoperative symptomatology and subsequent workup, postoperative complications, and symptom recurrence were collected and analyzed.

RESULTS

There were 56 patients included in the study. There was a 1.8:1 female:male ratio. The average patient age was 56 years old (range 23-85). The average duration of symptoms was 1-3 years. Thirty-eight percent of patients had undergone previous endoscopic therapy for gastroparesis (pyloric botox injection or pyloric dilation) and 16% of patients underwent multiple endoscopic therapies. Twenty-nine percent of patients were on a medication for gastroparesis. Past surgery was the most common gastroparesis etiology for POP (50% of patients). Diabetes (23%) and idiopathic (19%) were the other most common gastroparesis etiologies for POP. Nausea was the most common symptom at first follow-up (30%) but these patients continued to improve with 14% of patients continuing to endorse nausea at 6 months. Twenty-seven percent of patients developed symptom recurrence. Forty percent of patients with symptom recurrence underwent a repeat endoscopic or surgical therapy.

CONCLUSIONS

In this present study, POP leads to durable results in approximately 75% of patients with minimal complications. Furthermore, the majority of patients who do develop symptom recurrence do not require additional gastroparesis interventions.

Complications After Paraesophageal Hernia Repair

Paraesophageal hernia repair (PEHR) is a challenging operation both technically and because the affected patient population is typically older with more comorbidities. As a result, PEHR is associated with substantial morbidity. Morbidity and mortality following PEHR vary significantly depending on the acuity of the operation and size of the hernia. In addition to a higher risk for general peri- and postoperative complications there are a variety of other foregut specific complications to consider including, acute perioperative, early, and late reherniation, mesh-related complications, perforation, gastroparesis, pulmonary and insufflation-related complications, among others. This review focuses on the complication-specific data on incidence, recognition etiology and management.

AGA Clinical Practice Update on Gastric Peroral Endoscopic Myotomy for Gastroparesis: Commentary

DESCRIPTION

The purpose of this American Gastroenterological Association (AGA) Institute Clinical Practice Update (CPU) is to review the available evidence and provide expert advice regarding cognitive, procedural, and post-procedural aspects of performing gastric peroral endoscopic myotomy for the treatment of refractory gastroparesis.

METHODS

This CPU was commissioned and approved by the AGA Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership and underwent internal peer review by the CPUC and external peer review through standard procedures of Gastroenterology. This expert commentary incorporates important as well as recently published studies in this field, and it reflects the experiences of the authors who are advanced endoscopists with expertise in treating patients by performing third-space endoscopy and gastric peroral endoscopic myotomy.

Gastroparesis: An Evidence-Based Review for the Bariatric and Foregut Surgeon

Gastroparesis is a gastric motility disorder characterized by delayed gastric emptying. It is a rare disease and difficult to treat effectively; management is a dilemma for gastroenterologists and surgeons alike. We conducted a systematic review of the literature to evaluate current diagnostic tools as well as treatment options. We describe key elements in the pathophysiology of the disease, in addition to current evidence on treatment alternatives, including nutritional considerations, medical and surgical options, and related outcomes.

ACG Clinical Guideline: Gastroparesis

Gastroparesis is characterized by symptoms suggesting retention of food in the stomach with objective evidence of delayed gastric emptying in the absence of mechanical obstruction in the gastric outflow. This condition is increasingly encountered in clinical practice. These guidelines summarize perspectives on the risk factors, diagnosis, and management of gastroparesis in adults (including dietary, pharmacological, device, and interventions directed at the pylorus), and they represent the official practice recommendations of the American College of Gastroenterology. The scientific evidence for these guidelines was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation process. When the evidence was not appropriate for Grading of Recommendations, Assessment, Development, and Evaluation, we used expert consensus to develop key concept statements. These guidelines should be considered as preferred but are not the only approaches to these conditions.

POEM, GPOEM, and ZPOEM

Our tripartite narrative review discusses Peroral Endoscopic Myotomy (POEM), gastric POEM (GPOEM) and POEM for Zenker's diverticula (ZPOEM). POEM is the prototypical procedure that launched the novel "3rd space endoscopy" field of advanced endoscopy. It revolutionized achalasia therapy by offering a much less invasive version of the prior gold standard, the laparoscopic Heller myotomy (HM). We review in detail indications, outcomes, technique variations and comparative data between POEM and HM particularly with regard to the hotly debated issue of GERD. We then proceed to discuss two less illustrious but nevertheless important offshoots of the iconic POEM procedure: GPOEM for gastroparesis and ZPOEM for the treatment of hypopharyngeal diverticula. For GPOEM, we discuss the rationale of pylorus-directed therapies, briefly touch on GPOEM technique variations and then focus on the importance of proper patient selection and emerging data in this area. On the third and final part of our review, we discuss ZPOEM and expound on technique variations including our "ultra-short tunnel technique". Our review emphasizes that, despite the superiority of endoscopy over surgery for the treatment of hypopharyngeal diverticula, there is no clear evidence yet of the superiority of the newfangled ZPOEM technique compared to the conventional endoscopic myotomy technique practiced for over two decades prior to the advent of ZPOEM.

Endoscopic Management for Post-Surgical Complications after Resection of Esophageal Cancer

Simple Summary

Flexible endoscopy has an important part in the diagnosis and treatment of postoperative complications after oncologically intended esophagectomy. Endoscopy offers the possibility of effective therapy with minimal invasiveness at the same time, and the use of endoscopic therapy procedures can avoid re-operations. In this review we present the advantages of endoscopic treatment opportunities during the last 20 years regarding patients’ treatment after esophageal cancer resection. According to prevalence and clinical relevance, four relevant postoperative complications were identified and their endoscopic treatment procedures discussed. All endoscopic therapy procedures for anastomotic bleeding, anastomotic insufficiencies, anastomotic stenosis and postoperative delayed gastric emptying are presented, including innovative developments.

Abstract

Background: Esophageal cancer (EC) is the sixth-leading cause of cancer-related deaths in the world. Esophagectomy is the most effective treatment for patients without invasion of adjacent organs or distant metastasis. Complications and relevant problems may occur in the early post-operative course or in a delayed fashion. Here, innovative endoscopic techniques for the treatment of postsurgical problems were developed during the past 20 years. Methods: Endoscopic treatment strategies for the following postoperative complications are presented: anastomotic bleeding, anastomotic insufficiency, delayed gastric passage and anastomotic stenosis. Based on a literature review covering the last two decades, therapeutic procedures are presented and analyzed. Results: Addressing the four complications mentioned, clipping, stenting, injection therapy, dilatation, and negative pressure therapy are successfully utilized as endoscopic treatment techniques today. Conclusion: Endoscopic treatment plays a major role in both early-postoperative and long-term aftercare. During the past 20 years, essential therapeutic measures have been established. A continuous development of these techniques in the field of endoscopy can be expected.

Gastric per-oral endoscopic myotomy: Indications, technique, results and comparison with surgical approach

Gastroparesis is a chronic disease of the stomach that causes a delayed gastric emptying, without the presence of a stenosis. For 30 years the authors identified pylorospasm as one of the most important pathophysiological mechanisms determining gastroparesis. Studies with EndoFLIP, a device that assesses pyloric distensibility, increased the knowledge about pylorospasm. Based on this data, several pyloric-targeted therapies were developed to treat refractory gastroparesis: Surgical pyloroplasty and endoscopic approach, such as pyloric injection of botulinum and pyloric stenting. Notwithstanding, the success of most of these techniques is still not complete. In 2013, the first human gastric per-oral endoscopic myotomy (GPOEM) was performed. It was inspired by the POEM technique, with a similar dissection method, that allows pyloromyotomy. Therapeutical results of GPOEM are similar to surgical approach in term of clinical success, adverse events and post-surgical pain. In the last 8 years GPOEM has gained the attention of the scientific community, as a minimally invasive technique with high rate of clinical success, quickly prevailing as a promising therapy for gastroparesis. Not surprisingly, in referral centers, its technical success rate is 100%. One of the main goals of recent studies is to identify those patients that will respond better to the therapies targeted on pylorus and to choose the better approach for each patient.

Gastroparesis

Gastroparesis is characterized by symptoms suggestive of, and objective evidence of, delayed gastric emptying in the absence of mechanical obstruction. This review addresses the normal emptying of solids and liquids from the stomach and details the myogenic and neuromuscular control mechanisms, including the specialized function of the pyloric sphincter, that result in normal emptying, based predominantly on animal research. A clear understanding of fundamental mechanisms is necessary to comprehend derangements leading to gastroparesis, and additional research on human gastric muscles is needed. The section on pathophysiology of gastroparesis considers neuromuscular diseases that affect nonsphincteric gastric muscle, disorders of the extrinsic neural control, and pyloric dysfunction that lead to gastroparesis. The potential cellular basis for gastroparesis is attributed to the effects of oxidative stress and inflammation, with increased pro-inflammatory and decreased resident macrophages, as observed in full-thickness biopsies from patients with gastroparesis. Predominant diagnostic tests involving measurements of gastric emptying, the use of a functional luminal imaging probe, and high-resolution antral duodenal manometry in characterizing the abnormal motor functions at the gastroduodenal junction are discussed. Management is based on supporting nutrition; dietary interventions, including the physical reduction in particle size of solid foods; pharmacological agents, including prokinetics and anti-emetics; and interventions such as gastric electrical stimulation and pyloromyotomy. These are discussed briefly, and comment is added on the potential for individualized treatments in the future, based on optimal gastric emptying measurement and objective documentation of the underlying pathophysiology causing the gastroparesis.

[G-POEM - Gastric Peroral Endoscopic Myotomy as a Therapy Option for Chronic Gastric Emptying Disorders]

Many doctors and patients shy away from the surgical intervention of a pyloromyotomy using laparoscopy. The effectiveness of botulinum toxin injections into the pylorus has not been established 1 2. Pharmacological therapeutic approaches are unsatisfactory and show a wide range of side effects 3. G-POEM is a procedure that has proven its feasibility with a low complication rate. A relatively high response could be documented in previous publications 4. The long-term successes are still being discussed controversially 5. After the initial euphoria, the problem of patient selection comes to the fore. The symptoms, as well as the pathophysiology of gastric emptying disorder, are diverse 6. The diagnostic tests available do not reflect the variability of the disease 7 8 9 10. The postoperative gastric emptying disorder seems to be an exception. G-POEM can protect both therapists and patients from another invasive procedure.

Impact of gastric per-oral endoscopic myotomy on static and dynamic pyloric function in gastroparesis patients

BACKGROUND

Functional Lumen Imaging Probe (EndoFLIP) tests typically measure static pyloric parameters, but the pylorus exhibits phasic variations on manometry. Dynamic changes in pyloric function have not been quantified using EndoFLIP, and the impact of Gastric Per-Oral Endoscopic Myotomy (G-POEM) on static and dynamic pyloric activity in gastroparesis is unknown.

METHODS

EndoFLIP balloon inflation to 30, 40, and 50 mL was performed to measure mean, maximum, and minimum values and variability in pyloric diameter and distensibility before and after G-POEM in 20 patients with refractory gastroparesis. The impact of phasic contractions on these pyloric measures was compared.

KEY RESULTS

G-POEM increased mean (P < .0001) and maximum (P = .0002) pyloric diameters and mean (P = .02) and maximum (P = .02) pyloric distensibility on 50 mL EndoFLIP inflation but not intraballoon pressures or minimum diameters or distensibility. Temporal variability of pyloric diameter (P = .02) and distensibility (P = .02) also increased after G-POEM. Phasic coupled contractions propagating from the antrum through the pylorus were observed in 37.5% of recordings; other phasic activity including isolated pyloric contractions were seen in 23.3%. Variability of pyloric diameter and distensibility tended to be higher during recordings with phasic activity. Some pyloric responses to G-POEM were influenced by age, gastroparesis etiology, gastric emptying, and prior botulinum toxin injection.

CONCLUSIONS & INFERENCES

Pyloric activity exhibits dynamic changes on EndoFLIP testing in gastroparesis. G-POEM increases maximal but not minimal diameter and distensibility with increased variations, suggesting this therapy enhances pyloric opening but may not impair pyloric closure. Phasic pyloric contractions contribute to variations in pyloric activity.

Per Oral Pyloromyotomy for Gastroparesis: A Systematic Review of the Current Literature and Future Recommendations

Background: Gastric per oral endoscopic myotomy (GPOEM) was developed as a therapeutic option for gastroparesis after the pylorus was identified as a key target for gastroparesis management. This study includes a systematic literature review of studies in which GPOEM was utilized as therapy for gastroparesis. Methods: A literature search was conducted in three databases (MEDLINE, Scopus and Embase) of articles that included the keywords “GPOEM”, “Gastric per oral endoscopy myotomy” or “per oral pyloromyotomy” and “Gastroparesis” in the abstract or title. The search covered articles published until 29 February 2020. Results: A total of 139 articles were identified. Only 15 articles met the final inclusion criteria and were retrieved for qualitative data synthesis. Conclusion: GPOEM for gastroparesis is shown to have a high success rate among the studies but data interpretations are limited because of small sample sizes and short follow-up. Subjective and objective data prior to and post-GPOEM will be mandatory to establish credibility. The procedure is technically feasible and safe based on the limited studies available.

Teaching peroral endoscopic pyloromyotomy (POP) to practicing endoscopists: An "into-the-fire" approach to simulation

BACKGROUND

Peroral endoscopic pyloromyotomy, or gastric peroral endoscopic myotomy, is a novel endoscopic procedure for the treatment of refractory gastroparesis. We present a simulation-based curriculum using an "into-the-fire" approach with hands-on pre- and post-tests to teach this procedure.

METHODS

Six, 1-day peroral endoscopic pyloromyotomy courses were taught by an expert surgical endoscopist in 2018 to 2019. The curriculum is composed of a series of pretraining tests, lectures, mentored hands-on instruction, and post-training tests using porcine models. Both pre- and post-testing included a confidence survey, a knowledge-based written test, and a specific assessment form for the peroral endoscopic pyloromyotomy procedure. Participants' scores were analyzed using paired t tests.

RESULTS

Twenty-eight practicing physicians participated. After completing the curriculum, participants had improved confidence scores (10.5 ± 5.2 vs 19.4 ± 3.6; P < .001), written test scores (6.8 ± 1.6 vs 8.0 ± 1.1; P < .001), and hands-on performance scores (23.6 ± 3.4 vs 29.3 ± 1.4; P < .001) with marked improvement in all components of the peroral endoscopic pyloromyotomy procedure. Postcourse surveys showed 93% of participants had performed or intended to perform the peroral endoscopic pyloromyotomy procedure within the next year.

CONCLUSION

Our simulation curriculum with an into-the-fire approach to teach peroral endoscopic pyloromyotomy is effective in improving practitioner knowledge, confidence, and technical skills, leading to an increase in the adoption of this procedure.

Feasibility, safety, and long-term efficacy of gastric peroral endoscopic myotomy (G-POEM) for postsurgical gastroparesis: a single-center and retrospective study of a prospective database

BACKGROUND

Postsurgical gastroparesis is recognized as a gastrointestinal dysfunction syndrome following foregut surgery. Gastric peroral endoscopic myotomy (G-POEM) is suggested as a minimally invasive therapy for gastroparesis. But the long-term efficacy and safety of G-POEM in treating postsurgical gastroparesis are rarely explored.

METHODS

The primary outcomes included the symptomatic improvement based on gastroparesis cardinal symptoms index (GCSI) and the improvement of gastric emptying. The secondary outcomes included the improvement of gastroesophageal reflux symptoms and complications of G-POEM.

RESULTS

The severity of postsurgical gastroparesis was not associated with the onset time and the course of the disease. G-POEM significantly reduced GCSI throughout the follow-up period (p < 0.0001). For different anastomotic site, a significant improvement of GCSI was found at 6 month post-G-POEM (F_4,165 = 74.18, p < 0.0001). Subscale analysis of GCSI showed that nausea/vomiting, post-prandial fullness/early satiety, and bloating were improved significantly at 6-month post-G-POEM (p < 0.0001, respectively). Half-emptying and whole-emptying time were significantly shortened in patients with different anastomotic site post-G-POEM (half-emptying time: F_3,174 = 65.44, p < 0.0001; whole-emptying time: F_3,174 = 54.85, p < 0.0001). The emptying of ioversol was obviously accelerated after G-POEM. GCSI wasn't related to pyloric length, pyloric diameter, and thickness of pyloric wall. GERDQ was also used to evaluate the clinical efficacy of G-POEM. For each time points, GERDQ didn't differ significantly in patients with different anastomotic site (F_4,104 = 0.8075, p = 0.5231). For patients with different anastomotic site, GERDQ was improved significantly at different time points (F_4,104 = 59.11, p < 0.0001). The higher the esophageal anastomotic site was, the faster G-POEM improved the symptoms of gastroesophageal reflux. No one required re-hospitalization for any complication.

CONCLUSION

G-POEM is a minimally invasive therapy with long-term effectiveness and safety in treating postsurgical gastroparesis.

Targeting Treatment of Gastroparesis: Use of Clinical Tests to Guide Treatments

Gastroparesis presents with nausea, vomiting, and other upper gut symptoms, and is diagnosed by confirming delayed gastric emptying. A related condition, chronic unexplained nausea and vomiting, has similar symptoms but with normal emptying. Both conditions are managed using therapies with diverse mechanisms of action. Even though prokinetic treatments are proposed to improve gastroparesis by accelerating gastric emptying, there is limited evidence that they provide benefit by virtue of transit stimulating effects. Other tests can delineate alterations in other gut sensorimotor parameters in patients with suspected gastroparesis, but their relation to symptoms and their capability to guide treatment are largely unproved.

Peroral Pyloromytomy is Effective and Safe for Postsurgical Gastroparesis

Gastric Per-oral Endoscopic pyloromyotomy (G-POEM) or per-oral pyloromyotomy (POP) is a novel procedure recently described for treatment of medically refractory gastroparesis; however, its efficacy and safety is not clear in patients with postsurgical gastroparesis (PsGP). We conducted a systematic review and meta-analysis to determine the efficacy and safety of G-POEM in PsGP. A total of 6 studies were included in the analysis. The pooled rate of success by gastroparesis cardinal symptom index (GCSI) and 4-h gastric emptying study (GES) were 89.6% (95% C.I. 72.7-96.5) and 81.5% (95% CI 47.8-95.5) respectively. There was a statistically significant improvement in GCSI score after 3 months of G-POEM as compared with pre G-POEM GCSI scores (2.7 (95% C.I. 0-5.5) vs 8.2 (95% C.I. 5.4-11) (p = 0.007). The mean pre G-POEM 4 h GES was 93.8% (95% C.I. 42.3-145.3) with improvement in post G-POEM GES to 44.5% (95% C.I. 0-95)(p = 0.2). The pooled rate of total adverse events was 9% (95% C.I. 2.7-25.9). Our study showed a good clinical success of G-POEM in PsGP patients along with significant improvement in 3-month GCSI scores. There was an improvement of GES after G-POEM, but it did not reach statistical significance. In conclusion, G-POEM is an effective and safe treatment option for PsGP.

Patient factors influence surgical options in gastroparesis

BACKGROUND

Patient selection for the diverse surgical procedures for gastroparesis remains poorly defined. Our aim was to evaluate how patient factors have determined our surgical approach to gastroparesis.

METHODS

95 patients undergoing 105 surgical procedures for gastroparesis were reviewed. Patient factors were compared across six surgical procedures: gastric neurostimulator, pyloroplasty, neurostimulator plus pyloroplasty, sleeve gastrectomy, gastric bypass and gastrectomy. Global symptom severity was determined preoperatively and at last follow up.

RESULTS

There were significant differences in etiology, BMI and gastroesophageal reflux across the various operations. Patients undergoing pyloroplasty and gastrectomy; were more likely to have a postsurgical etiology. (p < .05) Patients undergoing sleeve gastrectomy and gastric bypass were more likely to have BMI >35. ^{(p <.05)} Those undergoing sleeve gastrectomy were less likely to have gastroesophageal reflux preoperatively. ^{(p <.05)} There was no difference in preoperative clinical stage across the procedures.

CONCLUSION

Patient factors influence choice of procedure in the surgical treatment of gastroparesis. Etiology of gastroparesis, BMI >35 and gastroesophageal reflux are important determinants.

Sleeve gastrectomy for treatment of delayed gastric emptying-indications, technique, and results

INTRODUCTION

Delayed gastric emptying (DGE) can be caused by gastric motility disorders such as gastroparesis with idiopathic background, diabetic neuropathy, or postsurgical nerve damage. Currently, a variety of endoscopic and surgical treatment options are available. We noted clinical improvement of gastric emptying with reduction of the gastric fundus following both fundoplication and fundectomy. As a consequence, we explored the effect of sleeve gastrectomy on gastric emptying. The focus of this paper is to investigate the role of laparoscopic sleeve gastrectomy (LSG) in the treatment of gastroparesis.

METHODS

Patients with symptoms suggestive of gastroparesis received diagnostic work-up (gastric emptying scintigraphy and/or Radiographic Barium-Sandwich Emptying studies). Patients with fundic emptying problems and moderate gastric dilation were selected for a LSG. All perioperative parameters were documented regarding patients characteristics, complications, and outcomes expressed as symptoms and quality of life (GIQLI gastrointestinal quality of life index). Assessment of DGE: Barium Emptying Radigraphy Index (BERI) 0-5.

RESULTS

From 122 patients with gastroparesis, 19 patients were selected for LSG (mean age 54 years (23-68); 10 males/9 females. Morbidity 2/19; no mortality; follow-up mean 24 months (12-60); preop/postop: BERI: 2, 31/1, 27 (p < 0.01); we noted significant improvement of the quality of life (preoperative GIQLI 78 (44-89)) to postoperative values of 114 (range 87-120) (p < 0.0001). Preoperative median BMI of these 19 patients was 24 [1-10], which was not significantly changed in the 15 patients at > 1 year follow-up with 23 [1-8]. Postoperative recurrence of DGE occurred in 3 patients who were reoperated after >1 year follow-up.

CONCLUSION

LSG is a potential surgical treatment option for selected patients with gastroparesis and fundic emptying problems.

Gastrectomy versus stomach left in situ with Roux-en-Y reconstruction for the treatment of gastroparesis

BACKGROUND

Gastroparesis is a debilitating functional disorder of the stomach marked by delayed gastric emptying in the absence of mechanical obstruction. Patients with severe, refractory symptoms may ultimately be managed with Roux-en-Y reconstruction; however, it is unclear whether the stomach should be left in situ, similar to a conventional gastric bypass, or resected as in gastrectomy.

METHODS

All patients undergoing Roux-en-Y for the treatment of gastroparesis (GP) at our institution from September 2010 through March 2018 were retrospectively reviewed. Patients with prior gastric resection or whose primary operative indication was not gastroparesis were excluded from analysis.

RESULTS

Twenty-six patients underwent Roux-en-Y with stomach left in situ (RY-SIS) and twenty-seven patients underwent gastrectomy with Roux-en-Y reconstruction during the study period. The mean age was 49.7 years in the RY-SIS cohort and 48.5 years in the gastrectomy cohort. Etiology of GP was similar between the two cohorts. Patients undergoing gastrectomy were more likely to have previous interventions for GP (63.0% vs. 26.9%). RY-SIS was associated with a shorter operative time (155 vs. 223 min), less blood loss (24 vs. 130 mL), and shorter length of stay (4.0 vs. 7.2 days). Twelve patients (44.4%) had complications within 30 days following gastrectomy compared to two patients (7.7%) following RY-SIS (p = 0.001). Patients in the RY-SIS cohort were more likely to require further subsequent surgical intervention for GP (23.1% vs. 3.7%, p = 0.04). At last follow-up, there were no differences in reported GP symptoms or symptom scoring.

CONCLUSIONS

Gastrectomy was associated with greater perioperative morbidity compared to leaving the stomach in situ. Symptomatic improvement at intermediate follow-up was equivalent following either procedure. However, patients undergoing RY-SIS were more likely to require subsequent surgical intervention, suggesting that gastrectomy may be a more definitive operation for the management of medically refractory gastroparesis.