Kinetics of transient hiatus hernia during transient lower esophageal sphincter relaxations and swallows in healthy subjects

Consensus statements and recommendations on the management of mild-to-moderate gastroesophageal reflux disease in the Southeast Asian region

This paper reports the proceedings from the first consensus meeting on the management of mild-to-moderate gastroesophageal reflux disease (GERD) in the Southeast Asian (SEA) region. Seventeen statements were drawn up by a steering committee that focused on epidemiology, mechanism of action, diagnostic investigations, and treatment. Voting on the recommendations used the Delphi method with two rounds of voting among the 10 panel members. The consensus panel agreed that GERD is mostly a mild disease in the SEA region with predominantly non-erosive reflux disease (NERD). Complicated GERD and Barrett's esophagus are infrequently seen. The panel recommended endoscopy in patients with alarm or refractory symptoms but cautioned that the incidence of gastric cancer is higher in SEA. pH and impedance measurements were not recommended for routine assessment. The acid pocket is recognized as an important pathogenic factor in GERD. Lifestyle measures such as weight reduction, avoidance of smoking, reduction of alcohol intake, and elevation of the head of the bed were recommended but strict avoidance of specific foods or drinks was not. Alginates was recommended as the first-line treatment for patients with mild-to-moderate GERD while recognizing that proton-pump inhibitors (PPIs) remained the mainstay of treatment of GERD. The use of alginates was also recommended as adjunctive therapy when GERD symptoms were only partially responsive to PPIs.

The virtual esophagus: investigating esophageal functions in silico

Esophageal and gastroesophageal junction (GEJ) diseases are highly prevalent worldwide and are a significant socioeconomic burden. Recently, applications of multiscale mathematical models of the upper gastrointestinal tract have gained attention. These in silico investigations can contribute to the development of a virtual esophagus modeling framework as part of the larger GIome and Physiome initiatives. There are also other modeling investigations that have potential screening and treatment applications. These models incorporate detailed anatomical models of the esophagus and GEJ, tissue biomechanical properties and bolus transport, sensory properties, and, potentially, bioelectrical models of the neural and myogenic pathways of esophageal and GEJ functions. A next step is to improve the integration between the different components of the virtual esophagus, encoding standards, and simulation environments to perform more realistic simulations of normal and pathophysiological functions. Ultimately, the models will be validated and will provide predictive evaluations of the effects of novel endoscopic, surgical, and pharmaceutical treatment options and will facilitate the clinical translation of these treatments.

Regulation and dysregulation of esophageal peristalsis by the integrated function of circular and longitudinal muscle layers in health and disease

Muscularis propria throughout the entire gastrointestinal tract including the esophagus is comprised of circular and longitudinal muscle layers. Based on the studies conducted in the colon and the small intestine, for more than a century, it has been debated whether the two muscle layers contract synchronously or reciprocally during the ascending contraction and descending relaxation of the peristaltic reflex. Recent studies in the esophagus and colon prove that the two muscle layers indeed contract and relax together in almost perfect synchrony during ascending contraction and descending relaxation of the peristaltic reflex, respectively. Studies in patients with various types of esophageal motor disorders reveal temporal disassociation between the circular and longitudinal muscle layers. We suggest that the discoordination between the two muscle layers plays a role in the genesis of esophageal symptoms, i.e., dysphagia and esophageal pain. Certain pathologies may selectively target one and not the other muscle layer, e.g., in eosinophilic esophagitis there is a selective dysfunction of the longitudinal muscle layer. In achalasia esophagus, swallows are accompanied by the strong contraction of the longitudinal muscle without circular muscle contraction. The possibility that the discoordination between two muscle layers plays a role in the genesis of esophageal symptoms, i.e., dysphagia and esophageal pain are discussed. The purpose of this review is to summarize the regulation and dysregulation of peristalsis by the coordinated and discoordinated function of circular and longitudinal muscle layers in health and diseased states.

Esophagogastric junction distensibility in hiatus hernia

Hiatus hernia is known to be an important risk factor for developing gastroesophageal reflux disease. We aimed to use the endoscopic functional lumen imaging probe (EndoFLIP) to evaluate the functional properties of the esophagogastric junction. EndoFLIP assessments were made in 30 patients with hiatus hernia and Barrett's esophagus, and in 14 healthy controls. The EndoFLIP was placed straddling the esophagogastric junction and the bag distended stepwise to 50 mL. Cross-sectional areas of the bag and intra-bag pressures were recorded continuously. Measurements were made in the separate sphincter components and hiatus hernia cavity. EndoFLIP measured functional aspects such as sphincter distensibility and pressure of all esophagogastric junction components and visualized all hiatus hernia present at endoscopy. The lower esophageal sphincter in hiatus hernia patients had a lower pressure (e.g. 47.7 ± 13.0 vs. 61.4 ± 19.2 mm Hg at 50-mL distension volume) and was more distensible (all P < 0.001) than the common esophagogastric junction in controls. In hiatus hernia patients, the crural diaphragm had a lower pressure (e.g. 29.6 ± 10.1 vs. 47.7 ± 13.0 mm Hg at 50-mL distension volume) and was more distensible (all P < 0.001) than the lower esophageal sphincter. There was a significant association between symptom scores in patients and EndoFLIP assessment. Conclusively, EndoFLIP was a useful tool. To evaluate the presence of a hiatus hernia and to measure the functional properties of the esophagogastric junction. Furthermore, EndoFLIP distinguished the separate esophagogastric junction components in hiatus hernia patients, and may help us understand the biomechanics of the esophagogastric junction and the mechanisms behind hiatal herniation.

Kinematic analysis of swallowing in the patients with esophagectomy for esophageal cancer

The aim of this study is to reveal the mechanism of esophagectomy-mediated swallowing motion disorders. Forty-seven patients who underwent 3-stage esophagectomy with cervical anastomosis and VFSS for esophageal cancer were selected. Twenty-three patients displayed subglottic aspiration (aspiration group) and the other 24 patients did not show any aspiration or penetration in the videofluoroscopic swallowing study after esophagectomy (no aspiration group). For comparison, 27 healthy volunteers (normal group) were included. Maximal anterior displacement of the hyoid (MADH), maximal superior displacement of the hyoid (MSDH), maximal rotation of the epiglottis (MRE) and pharyngeal delay time (PDT) were measured by image J software. MADH, MRE, and PDT in normal group were significantly different from those in aspiration and no aspiration groups (P<0.001). The normal group displayed a significantly different PDT compared to the no aspiration and aspiration groups, and the no aspiration group had a significantly different PDT compared to the aspiration group (P<0.001). The mechanism of swallowing motion disorders caused by the esophagectomy in esophageal cancer includes the decreased anterior movement of the hyoid and rotation of the epiglottis caused by the prolonged operation time and delayed pharyngeal reflex caused by the laryngeal sensory disturbance. Among them, the main mechanism of subglottic aspiration after esophagectomy is the delayed pharyngeal reflex.

Endoscopic assessment of reflux esophagitis concurrent with hiatal hernia in male Japanese patients with obstructive sleep apnea

OBJECTIVE

The pathogenetic relationship underlying the high prevalence of gastroesophageal reflux disease (GERD) in patients with obstructive sleep apnea (OSA) remains unclear. In addition, GERD has not been adequately assessed by endoscopy in patients with OSA. The purpose of this study was to use endoscopy to investigate potential interactions among reflux esophagitis, hiatal hernia (HH) and OSA.

MATERIAL AND METHODS

A total of 243 consecutive male Japanese participants who underwent both overnight ambulatory polygraphic monitoring and esophagogastroduodenoscopy were retrospectively evaluated in a cross-sectional study. The prevalence and severity of HH and reflux esophagitis were assessed according to the Los Angeles classification and the Makuuchi classification, respectively. Associations among reflux esophagitis, HH and OSA were examined by univariate and multivariate analyses.

RESULTS

OSA was diagnosed in 98 individuals (40.3%). Endoscopy-confirmed esophagitis (p = 0.027) and HH (p < 0.001) were significantly more prevalent among patients with OSA. Multivariate regression model analysis adjusted for age, body mass index, visceral obesity represented by waist circumference, presence of OSA, concurrence of OSA and HH, smoking, and alcohol consumption yielded OSA as the only variable significantly associated with HH (odds ratio [OR], 2.60; 95% confidence interval [CI], 1.35-4.99; p = 0.004), while concurrence of OSA and HH was related to reflux esophagitis (OR, 3.59; CI, 1.87-6.92; p < 0.001).

CONCLUSIONS

OSA was associated with HH and concurrent OSA and HH with reflux esophagitis in male Japanese patients with OSA. Our results support the hypothesis that complicating HH may link reflux esophagitis to OSA.

Waist belt and central obesity cause partial hiatus hernia and short-segment acid reflux in asymptomatic volunteers

OBJECTIVE

There is a high incidence of inflammation and metaplasia at the gastro-oesophageal junction (GOJ) in asymptomatic volunteers. Additionally, the majority of patients with GOJ adenocarcinomas have no history of reflux symptoms. We report the effects of waist belt and increased waist circumference (WC) on the physiology of the GOJ in asymptomatic volunteers.

DESIGN

12 subjects with normal and 12 with increased WC, matched for age and gender were examined fasted and following a meal and with waist belts on and off. A magnet was clipped to the squamo-columnar junction (SCJ). Combined assembly of magnet-locator probe, 12-channel pH catheter and 36-channel manometer was passed.

RESULTS

The waist belt and increased WC were each associated with proximal displacement of SCJ within the diaphragmatic hiatus (relative to upper border of lower oesophageal sphincter (LOS), peak LOS pressure point and pressure inversion point, and PIP (all p<0.05). The magnitude of proximal migration of SCJ during transient LOS relaxations was reduced by 1.6-2.6 cm with belt on versus off (p=0.01) and in obese versus non-obese (p=0.04), consistent with its resting position being already proximally displaced. The waist belt, but not increased WC, was associated with increased LOS pressure (vs intragastric pressure) and movement of pH transition point closer to SCJ. At 5 cm above upper border LOS, the mean % time pH <4 was <4% in all studied groups. Acid exposure 0.5-1.5 cm above SCJ was increased, with versus without, belt (p=0.02) and was most marked in obese subjects with belt.

CONCLUSIONS

Our findings indicate that in asymptomatic volunteers, waist belt and central obesity cause partial hiatus herniation and short-segment acid reflux. This provides a plausible explanation for the high incidence of inflammation and metaplasia and occurrence of neoplasia at the GOJ in subjects without a history of reflux symptoms.

Esophageal manometry in gastroesophageal reflux disease

High-resolution manometry (HRM) allows nuanced evaluation of esophageal motor function, and more accurate evaluation of lower esophageal sphincter (LES) function, in comparison with conventional manometry. Pathophysiologic correlates of gastroesophageal reflux disease (GERD) and esophageal peristaltic performance are well addressed by this technique. HRM may alter the surgical decision by assessment of esophageal peristaltic function and exclusion of esophageal outflow obstruction before antireflux surgery. Provocative testing during HRM may assess esophageal smooth muscle peristaltic reserve and help predict the likelihood of transit symptoms following antireflux surgery. HRM represents a continuously evolving new technology that compliments the evaluation and management of GERD.

Disruption of the gastroesophageal junction by central obesity and waist belt: role of raised intra-abdominal pressure

Obesity is a major reason for the recent increase in incidence of reflux disease and cancers at the distal esophagus and gastroesophageal junction (GOJ) and is mediated through a rise in the intra-abdominal pressure (IAP) but the exact mechanisms are unclear. Raised IAP from obesity and with application of waist belt produces mechanical distortion of the GOJ through formation of partial hiatus hernia. Even though there is no trans-sphincteric acid reflux, there is increased ingress of acid into the lower sphincter (intra-sphincteric reflux) as a consequence of raised IAP. In addition, short segment acid reflux is more evident in obese subjects with a belt on. Acid pocket is also enlarged in hiatus hernia, and acts as a reservoir of acid available to reflux whenever the sphincter fails. Above mechanisms may explain the common occurrence of cardiac lengthening and inflammation found in asymptomatic obese subjects. The inflamed cardia is also immunohistochemically similar to non-intestinal Barrett's mucosa, which is of etiological importance for cancers at the GOJ. Interventions that can reduce the mechanical distortion and acid exposure at the GOJ, including diet, exercise, drugs, sphincter augmentation therapy, and surgery, are clinically relevant in the treatment of gastroesophageal reflux disease but more data are needed whether if these strategies are also effective in preventing cancer. As a conclusion, raised IAP produces silent mechanical disruption of the GOJ, which may explain the high occurrence of cancers in this region and it is potentially reversible with early interventions.

Gastric acid pocket and gastroesophageal reflux disease

Gastric acid pocket is an area of highly acid that escapes the neutralization of food in the proximal stomach after meals and has been noticed in healthy individuals and gastroesophageal reflux disease (GERD) patients. It was first found by Fletcher et al, who carried out a series of experiments in 2001. After that, other researchers have carried out in-depth studies on it. Hiatus hernia, gastric motility, gastric anatomy and physiology seem to be important elements for the genesis of postprandial proximal gastric acid pocket (PPGAP). Because PPGAP may play an important role in the pathogenesis of GERD, treatments for suppressing the production of gastric acid, antacid agents, prokinetic agents, surgery and other treatments may be used to alter the presence of PPGAP to achieve the purpose of treating GERD. Therefore, the discovery of gastric acid pocket may provide a new idea for the treatment of GERD.

The acid pocket: a target for treatment in reflux disease?

The nadir esophageal pH of reflux observed during pH monitoring in the postprandial period is often more acidic than the concomitant intragastric pH. This paradox prompted the discovery of the "acid pocket", an area of unbuffered gastric acid that accumulates in the proximal stomach after meals and serves as the reservoir for acid reflux in healthy individuals and gastroesophageal reflux disease (GERD) patients. However, there are differentiating features between these populations in the size and position of the acid pocket, with GERD patients predisposed to upward migration of the proximal margin onto the esophageal mucosa, particularly when supine. This upward migration of acid, sometimes referred to as an "acid film", likely contributes to mucosal pathology in the region of the squamocolumnar junction. Furthermore, movement of the acid pocket itself to a supradiaphragmatic location with hiatus hernia increases the propensity for acid reflux by all conventional mechanisms. Consequently, the acid pocket is an attractive target for GERD therapy. It may be targeted in a global way with proton pump inhibitors that attenuate acid pocket development, or with alginate/antacid combinations that colocalize with the acid pocket and displace it distally, thereby demonstrating the potential for selective targeting of the acid pocket in GERD.

Pathophysiology of gastroesophageal reflux disease

The gastroesophageal junction is structurally complex and functionally designed to ensure the acid secreted by the most proximal gastric mucosa flows towards the stomach and not up onto the oesophageal squamous mucosa. The pattern and mechanism of reflux vary with the severity of reflux disease and this probably represents different ends of a spectrum rather than distinct pathophysiological mechanisms. Nearly all patients with severe reflux disease have hiatus hernia, however, a substantial proportion of patients with mild reflux disease do not, and this may be a result of intermittent or partial hiatus hernia undetectable by current available tools. The acid pocket is an area of post-prandial unbuffered gastric acidity immediately distal to the gastroesophageal junction and which is enlarged in patients with hiatus hernia. The acid pocket provides a reservoir of acid available to reflux when the intrinsic sphincter fails. Central obesity is an important factor in the aetiology of reflux and does this by the increased abdomino-thoracic pressure gradient inducing hiatus hernia and increasing the rate of flow of reflux when sphincter opens. Central obesity also induces short segment intrasphincteric reflux and thereby columnar metaplasia of the most distal oesophagus.

Measuring movement and location of the gastroesophageal junction: research and clinical implications

Understanding the physiology of gastroesophageal junction (GEJ) is important as failure of its function is associated with reflux disease, hiatus hernia, and cancer. In recent years, there have been impressive developments in high resolution technologies allowing measurement of luminal pressure, pH, and impedance. One obvious deficiency is the lack of technique to monitor the movement and location of the GEJ over a prolonged period of time. Proximal movement of the GEJ during peristalsis and transient lower esophageal sphincter relaxations (TLESRs) is due to shortening of the longitudinal muscle of the esophagus. Techniques for measuring shortening include fluoroscopic imaging of mucosal clip, high-frequency intraluminal ultrasound, and high resolution manometry, but these techniques have limitations. Short segment reflux is recently found to be more common than traditional reflux and may account for the high prevalence of intestinal metaplasia and cancer seen at GEJ. While high resolution pHmetry is available, there is no technique that can reliably and continuously measure the position of the squamocolumnar junction. A new technique is recently reported allowing a precise and continuous measurement of the GEJ based on the principle of Hall effect. Reported studies have validated its accuracy both on the bench and against the gold standard, fluoroscopy. It has been used alongside high resolution manometry in studying the behavior of the GEJ during TLESRs and swallows. While there are challenges associated with this new technique, there are promising ongoing developments. There is exciting time ahead in research and clinical applications for this new technique.