Pathophysiology of gastroesophageal reflux disease-which factors are important?

Personalized anti-reflux surgery: connecting GERD phenotypes in 690 patients to outcomes

BACKGROUND

Anti-reflux operations are effective treatments for GERD. Despite standardized surgical techniques, variability in post-operative outcomes persists. Most patients with GERD possess one or more characteristics that augment their disease and may affect post-operative outcomes-a GERD "phenotype". We sought to define these phenotypes and to compare their post-operative outcomes.

METHODS

We performed a retrospective review of a prospective gastroesophageal database at our institution, selecting all patients who underwent an anti-reflux procedure for GERD. Patients were grouped into different phenotypes based on the presence of four characteristics known to play a role in GERD: hiatal or paraesophageal hernia (PEH), hypotensive LES, esophageal dysmotility, delayed gastric emptying (DGE), and obesity. Patient-reported outcomes (GERD-HRQL, dysphagia, and reflux symptom index (RSI) scores) were compared across phenotypes using the Wilcoxon rank-sum test.

RESULTS

690 patients underwent an anti-reflux procedure between 2008 and 2022. Most patients underwent a Nissen fundoplication (302, 54%), followed by a Toupet or Dor fundoplication (205, 37%). Twelve distinct phenotypes emerged. Non-obese patients with normal esophageal motility, normotensive LES, no DGE, with a PEH represented the most common phenotype (134, 24%). The phenotype with the best post-operative GERD-HRQL scores at one year was defined by obesity, hypotensive LES, and PEH, while the phenotype with the worst scores was defined by obesity, ineffective motility, and PEH (1.5 ± 2.4 vs 9.8 ± 11.4, p = 0.010). There was no statistically significant difference in GERD-HRQL, dysphagia, or RSI scores between phenotypes after five years.

CONCLUSIONS

We have identified distinct phenotypes based on common GERD-associated patient characteristics. With further study these phenotypes may aid surgeons in prognosticating outcomes to individual patients considering an anti-reflux procedure.

Obesity related pathophysiological aspects favouring Gastroesophageal Reflux Disease

Gastroesophageal reflux disease (GERD) is a complex entity and one of the most frequents in general population. Association of GERD with obesity is clearly defined from an epidemiological point of view, where up to 40% of patients with overweight and obesity present reflux. Most of the risk factors associated to GERD are shared and especially frequent in patients with obesity. The pathophysiology that explain this correlation is complex and multifactorial, and includes both aspects related to physiology of motility, and anatomic changes. The malfunction of the lower esophageal sphincter, the greater transdiaphragmatic pressure gradient, pathological accumulation of fat and the high rate of hiatal hernia that comes with overweight will be the main factors that explain this correlation. Other factor like pathological eating habits or obesity related diseases have also an important role. In summary, it is the sum of the factors more than just one of them what would explain the pathophysiology of GERD in obese population.

Developments in Gastroesophageal Reflux Disease over the Last 40 Years

BACKGROUND

The last 40 years have seen a remarkable change in our understanding of reflux disease.

SUMMARY

These changes encompass disease definition and impact, pathophysiology, diagnostic testing, regulatory oversight of clinical trials, pharmacotherapy, endoscopic, and surgical treatment. We have also seen a number of promising therapies fail.

KEY MESSAGES

The future holds the promise of further advances. Adaptive artificial intelligence will take over diagnostics in manometry and pH impedance testing and patient-driven outcomes may be changed by interactions with artificial intelligence rather than humans. Changes in chip technology will allow higher resolution chips to be carried on smaller devices making extra-esophageal areas where reflux may play a role more accessible to prolonged observation and testing.

Chitosan Nanoparticles for Gastroesophageal Reflux Disease Treatment

Gastroesophageal Reflux Disease (GERD) is a chronic ailment that results from the backward flow of stomach acid into the esophagus, causing heartburn and acid regurgitation. This review explores nanotechnology as a novel treatment approach for GERD. Chitosan nanoparticles (CSNPs) offer several advantages, including biocompatibility, biodegradability, and targeted drug delivery capabilities. CSNPs have been extensively studied due to their ability to encapsulate and release medications in a controlled manner. Different nanoparticle (NP) delivery systems, including gels, microspheres, and coatings, have been developed to enhance drug retention, drug targeting, and controlled release in the esophagus. These nanoparticles can target specific molecular pathways associated with acid regulation, esophageal tissue protection, and inflammation modulation. However, the optimization of nanoparticle formulations faces challenges, including ensuring stability, scalability, and regulatory compliance. The future may see CSNPs combined with other treatments like proton pump inhibitors (PPIs) or mucosal protectants for a synergistic therapeutic approach. Thus, CSNPs provide exciting opportunities for novel GERD treatment strategies.

Prediction of gastroesophageal reflux episodes by smooth muscle electromyography: A translational study in rats and adolescents

Aims

Our aim was to measure the myoelectric modifications during gastric acid secretion along with the gastric pH in a rat model and to detect the gastrointestinal (GI) myoelectric changes in adolescents suffering from gastroesophageal reflux disease (GERD) along with the esophageal pH measurement.

Main methods

In anesthetized rats, gastric acid secretion was initiated with intragastric histamine (50 mg/kg), and gastric pH, GI myoelectric activity and mechanical GI contractions were measured with intragastric pH electrode, subcutaneously implanted smooth muscle electromyography (SMEMG) electrodes and organ implanted strain gauges, respectively. In the clinical study, esophageal pH and GI myoelectric activity were measured in adolescents suffering from GERD with intraesophageal pH electrode and SMEMG electrodes placed on the abdominal surface, respectively. The SMEMG records were analyzed by fast Fourier transformation (FFT) and power spectrum density maximum (PsDmax) values were calculated for the GI segments.

Key findings

In rats, histamine initiated an immediate increase in gastric PsDmax, which preceded the significant reduction in gastric pH by 75 min. The myoelectric change was independent of mechanical GI contractions. In adolescents, the GERD episodes were preceded by a significant increase in gastric PsDmax 45 min earlier. These changes were independent of motion or meals.

Significance

Increased gastric myoelectric activity during histamine stimulation or GERD might be linked to the enhanced activity of the gastric proton pump, indicating a link between gastric acid secretion and GERD episodes. It is supposed that SMEMG might be a tool for predicting forthcoming reflux episodes in GERD.

Reconstruction of the human lower esophageal sphincter based on ultra-mill imaging for biomechanical analysis

Introduction: The lower esophageal sphincter (LES) controls the passage into the stomach and prevents reflex of contents into the esophagus. Dysfunctions of this region typically involves impairment of muscular function, leading to diseases including gastro-esophageal reflux disease and achalasia. The main objective of this study was to develop a finite element model from a unique human LES dataset reconstructed from an ultra-mill imaging setup, and then to investigate the effect of anatomical characteristics on intraluminal pressures. Methods: A pipeline was developed to generate a mesh from a set of input images, which were extracted from a unique ultra-mill sectioned human LES. A total of 216 nodal points with cubic Hermite basis function was allocated to reconstruct the LES, including the longitudinal and circumferential muscles. The resultant LES mesh was used in biomechanical simulations, utilizing a previously developed LES mathematical model based on the Visible Human data to calculate intraluminal pressures. Anatomical and functional comparisons were made between the Ultra-mill and Visible human models. Results: Overall, the Ultra-mill model contained lower cavity (1,796 vs. 5,400 mm3) and muscle (1,548 vs. 15,700 mm3) volumes than the Visible Human model. The Ultra-mill model also developed a higher basal pressure (13.8 vs. 14.7 mmHg) and magnitude of pressure (19.8 vs. 18.9 mmHg) during contraction. Out of all the geometric transformations (i.e., uniform enlargement of volume, lengthening along the center-axis, dilation of the diameter, and increasing muscle thickness), the muscle volume was found to be the main contributor of basal and magnitude of pressures. Increases in length also caused proportional increases to pressures, while dilation of diameter had a less influential reverse effect. Discussion: The findings provide information on interindividual variability in LES pressure and demonstrates that anatomy has a large influence on pressures. This model forms the basis of more complex simulations involving food bolus transport and predicting LES dysfunctions.

CT Evaluation of the Esophagus: The Role of CT Imaging and CT Imaging Findings in Diagnosing Esophageal Abnormalities

Esophageal disorders are commonly encountered by radiologists on computed tomography. Characteristic computed tomography findings of various esophageal pathologies have been extensively described and are important for the radiologist to know to facilitate accurate and timely diagnosis. Esophageal disorders can be broadly classified as infectious and inflammatory, congenital/structural, or neoplastic. This paper reviews the most common presentations of various esophageal pathologies within each classification.

Progress in research of pathogenesis of refractory gastroesophageal reflux disease

Refractory gastroesophageal reflux disease (rGERD) is a common clinical disease with many pathogenic factors, complex mechanisms, and increasing incidence. At present, scholars believe that the pathogenesis of rGERD is closely related to intra- and extra-esophageal factors. Elucidating the mechanism of rGERD can contribute to the diagnosis and treatment of the disease. This paper summarizes the current progress in the research of the pathogenesis of rGERD, and puts forward our own thoughts and prospects for the disease, in order to provide ideas for the in-depth study of the pathogenesis of rGERD.

Preoperative reflux or regurgitation symptoms are independent predictors of postoperative nausea and vomiting (PONV) in patients undergoing bariatric surgery: a propensity score matching analysis

BACKGROUND

Postoperative nausea and vomiting (PONV) is common side effect after gastrointestinal surgery. It causses discomfort, increase risk of incision disruption, bleeding and airway blockage. This study aimed to investigate the incidence and severity of PONV and determine whether preoperative reflux or regurgitation symptoms influence PONV in patients undergoing bariatric surgery.

METHODS

Patients with obesity underwent laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) in our center between January 2016 and December 2018 were divided into PONV and NoPONV group and analyzed retrospectively. PONV and postoperative pain visual analogue scale (VAS) were analyzed after surgery. A 1:1 propensity score matching (PSM) method was performed, and multivariable logistic regression analyses were used to identify predictors for PONV.

RESULTS

There were 483 patients enrolled, with a mean age of 30.19 ± 9.96 years, and 134 pairs of matched patients were selected from PONV group and NoPONV group after PSM. PONV occurred in 288 (59.6%) patients after bariatric surgery (77.4% after LSG vs 21.5% after LRYGB, p < 0.001). In PONV group, 210 (72.9%) were female, preoperative reflux or regurgitation symptoms were 128 (33.6%). Multivariable analysis found that preoperative reflux or regurgitation symptoms were independent risk factors for PONV after LSG, with an OR of 2.78 (95% CI: 1.12-6.93, p = 0.028).

CONCLUSIONS

Incidence of PONV after bariatric surgery is high. For the first time, this study valued preoperative reflux or regurgitation symptoms as risk factors that may promote PONV after bariatric surgery. Patients with preoperative symptoms undergoing LSG have a higher risk of PONV, so these patients should be carefully evaluated for the feasibility of LSG before surgery.