What strategies can strengthen the pylorus?

Strategies for Strengthening the Pylorus

For patients with pyloric dysfunction, gastric peroral endoscopic myotomy (G-POEM) is currently the most effective intervention for strengthening pyloric function in refractory gastroparesis, particularly in diabetic gastroparesis patients who show the highest frequency of clinical success (89%). 1

Understanding Pyloric Function and Dysfunction

• The pylorus plays a critical role in controlling gastric emptying through regulation of tone, pressure, and coordination with antral contractions 2
• Abnormalities of pyloric tone and pressure (pylorospasm) and dyscoordination between antral contractions and pyloric relaxation may impair gastric emptying and contribute to gastroparesis symptoms 2
• Deep pyloric biopsies have demonstrated that pyloric stenosis and reduced numbers of interstitial cells of Cajal may contribute to pyloric dysfunction 2
• The pylorus is not an isolated sphincter but rather a concentration of muscle bundles derived from antral muscles interwoven with the aboral sphincter complex of the stomach 3

Diagnostic Approaches for Pyloric Function

• Accurately measuring pyloric basal tone, phasic pressures, and relaxation is difficult; traditional methods like endoscopy, fluoroscopy, and antroduodenal manometry have significant limitations 2
• The functional lumen imaging probe (FLIP) uses impedance planimetry to record cross-sectional area and minimum diameter of the pylorus, providing estimates of sphincter distensibility and compliance 2
• FLIP has shown diminished pyloric distensibility in select patients with gastroparesis, but has not been validated to distinguish physiological from pathological changes across all causes of gastroparesis 2
• High-resolution antroduodenal manometry is another emerging diagnostic modality for assessing pyloric function 4

Therapeutic Interventions for Pyloric Strengthening

Pharmacological Approaches

• Metoclopramide increases the tone and amplitude of gastric (especially antral) contractions while relaxing the pyloric sphincter, resulting in accelerated gastric emptying 5
• Metoclopramide's effects begin at about 5 mg doses and increase through 20 mg, with effects lasting between 45 minutes (5 mg) and 2-3 hours (20 mg) 5
• Opioid analgesics should be avoided as they further delay gastric emptying and can worsen pyloric dysfunction 2

Endoscopic Interventions

• Gastric peroral endoscopic myotomy (G-POEM) has emerged as a promising technique for treating pyloric dysfunction in refractory gastroparesis 2
• G-POEM involves creating a submucosal tunnel and performing a pyloromyotomy, similar to the POEM technique used for achalasia 2
• Two separate multicenter trials have noted improvement in symptoms and reduction in gastric emptying times with G-POEM 2
• Pooled analysis of multiple studies suggests a reduction in post-procedure GCSI scores and improved gastric emptying, with 6.8% overall adverse events 2, 1
• Double myotomy (performing two pyloromyotomy incisions) during G-POEM has shown superior results to single myotomy in short-term follow-up 2

Other Interventions with Limited Evidence

• Intrapyloric botulinum toxin injection showed promise in early studies but two larger placebo-controlled studies showed no benefit over placebo 2
• One study suggested benefit of botulinum toxin in gastroparesis with decreased pyloric distensibility on FLIP, but this requires further confirmation 2
• Transpyloric stent placement should be considered investigational due to lack of data from prospective, sham-controlled trials and concerns over stent migration 2

Patient Selection and Procedural Considerations

• G-POEM should be considered for patients with medically refractory gastroparesis who have undergone esophagogastroduodenoscopy to confirm no mechanical gastric obstruction 2
• G-POEM has shown efficacy in treating patients with gastroparesis from diabetes, prior surgery, and idiopathic causes 2
• Patients should remain on a liquid diet for at least 24 hours before G-POEM to minimize residual gastric contents 2
• Periprocedural antibiotics with efficacy against enteric pathogens should be administered 2
• G-POEM should only be performed at tertiary care centers using a team approach of experts (motility specialists, advanced endoscopists) with extensive experience in treating refractory gastroparesis patients 2, 1

Post-Procedure Management

• Patients are typically admitted overnight for observation after G-POEM 2
• A clear-liquid diet can be started if there are no adverse events, followed by advancement to a full-liquid diet after confirming no contrast leakage 2
• A full-liquid diet for 5-7 days is generally advised, after which patients advance to consuming 5-6 small meals per day of a low-fiber, low-fat, solid-food gastroparesis diet 2
• Eight weeks of proton-pump inhibitor therapy is suggested to decrease acid secretion and aid in mucosal healing 2
• Follow-up in clinic is recommended approximately 1-3 months after G-POEM, with a follow-up solid-phase gastric emptying study advised no sooner than 4-8 weeks after the procedure 2