Pharmacological dissection of the human gastro-oesophageal segment into three sphincteric components

Kyoto international consensus report on anatomy, pathophysiology and clinical significance of the gastro-oesophageal junction

OBJECTIVE

An international meeting was organised to develop consensus on (1) the landmarks to define the gastro-oesophageal junction (GOJ), (2) the occurrence and pathophysiological significance of the cardiac gland, (3) the definition of the gastro-oesophageal junctional zone (GOJZ) and (4) the causes of inflammation, metaplasia and neoplasia occurring in the GOJZ.

DESIGN

Clinical questions relevant to the afore-mentioned major issues were drafted for which expert panels formulated relevant statements and textural explanations.A Delphi method using an anonymous system was employed to develop the consensus, the level of which was predefined as ≥80% of agreement. Two rounds of voting and amendments were completed before the meeting at which clinical questions and consensus were finalised.

RESULTS

Twenty eight clinical questions and statements were finalised after extensive amendments. Critical consensus was achieved: (1) definition for the GOJ, (2) definition of the GOJZ spanning 1 cm proximal and distal to the GOJ as defined by the end of palisade vessels was accepted based on the anatomical distribution of cardiac type gland, (3) chemical and bacterial (Helicobacter pylori) factors as the primary causes of inflammation, metaplasia and neoplasia occurring in the GOJZ, (4) a new definition of Barrett's oesophagus (BO).

CONCLUSIONS

This international consensus on the new definitions of BO, GOJ and the GOJZ will be instrumental in future studies aiming to resolve many issues on this important anatomic area and hopefully will lead to better classification and management of the diseases surrounding the GOJ.

Assessment of esophagogastric junction morphology by dynamic real-time MRI: comparison of imaging features to high-resolution manometry

Purpose

To assess the esophagogastric junction (EGJ) on real-time MRI and compare imaging parameters to EGJ morphology on high-resolution manometry (HRM).

Methods

A total of 105 of 117 eligible patients who underwent real-time MRI and high-resolution manometry for GERD-like symptoms between 2015 and 2018 at a single center were retrospectively evaluated (male n = 57; female n = 48; mean age 52.5 ± 15.4 years). Real-time MRI was performed at a median investigation time of 15 min (1 frame/40 ms). On HRM, EGJ morphology was assessed according to the Chicago classification of esophageal motility disorders. Real-time MRI was performed at 3 T using highly undersampled radial fast low-angle shot acquisitions with NLINV image reconstruction. A 10 mL pineapple juice bolus served as oral contrast agent at supine position. Real-time MRI films of the EGJ were acquired during swallowing events and during Valsalva maneuver. Anatomic and functional MRI parameters were compared to EGJ morphology on HRM.

Results

On HRM, n = 42 patients presented with EGJ type I (40.0%), n = 33 with EGJ type II (31.4%), and n = 30 with EGJ type III (28.6%). On real-time MRI, hiatal hernia was more common in patients with EGJ type III (66.7%) than in patients with EGJ type I (26.2%) and EGJ type II (30.3%; p < 0.001). Sliding hiatal hernia was more frequent in patients with EGJ type II (33.3%) than in patients with EGJ type III (16.7%) and EGJ type I (7.1%; p = 0.017). The mean esophagus–fundus angle of patients was 85 ± 31° at rest and increased to 101 ± 36° during Valsalva maneuver.

Conclusion

Real-time MRI is a non-invasive imaging method for assessment of the esophagogastric junction. Real-time MRI can visualize dynamic changes of the EGJ during swallowing events.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11604-021-01210-9.

Three-Dimensional Pressure Profile of the Lower Esophageal Sphincter and Crural Diaphragm in Patients with Achalasia Esophagus

BACKGROUND & AIMS

Smooth muscles of the lower esophageal sphincter (LES) and skeletal muscle of the crural diaphragm (esophagus hiatus) provide the sphincter mechanisms at the esophagogastric junction (EGJ). We investigated differences in the 3-dimensional (3D) pressure profile of the LES and hiatal contraction between healthy subjects and patients with achalasia esophagus.

METHODS

We performed a prospective study of 10 healthy subjects (controls; 7 male; mean age, 60 ± 15 years; mean body mass index, 25 ± 2) and 12 patients with a diagnosis of achalasia (7 male; mean age, 63 ± 13 years; mean body mass index, 26 ± 1), enrolled at a gastroenterology clinic. Participants underwent 3D high-resolution manometry (3DHRM) with a catheter equipped with 96 transducers (for the EGJ pressure recording). A 0.5-mm metal ball was taped close to the transducer number 1 of the 3DHRM catheter. EGJ pressure was recorded at end-expiration (LES pressure) and at the peak of forced inspiration (hiatal contraction). Computed tomography (CT) scans were performed to localize the circumferential location of the metal ball on the catheter. Esophagus, LES, stomach, right and left crus of the diaphragm, and spine were segmented in each CT scan slice images to construct the 3D morphology of the region.

RESULTS

The metal ball was located at the 7 o'clock position in all controls. The circumferential orientation of metal ball was displaced 45 to 90 degrees in patients with achalasia compared with controls. The 3D-pressure profile of the EGJ at end-expiration and forced inspiration revealed marked differences between the groups. The LES turns to the left as it entered from the chest into the abdomen, forming an angle between the spine and LES. The spine-LES angle was smaller in patients with achalasia (104°) compared with controls (124°). Five of the 10 subjects with achalasia had physical breaks in the left crus of the diaphragm CONCLUSIONS: Besides LES, the 3D pressure profile of the EGJ can indicate anatomic and functional abnormalities of the crural diaphragm muscle in patients with achalasia esophagus. Further studies are needed to define the nature of hiatal and crural diaphragm dysfunction in patients with achalasia of the esophagus.

Tissue engineering of the gastroesophageal junction

The gastroesophageal junction has been of clinical interest for some time due to its important role in preventing reflux of caustic stomach contents upward into the esophagus. Failure of this role has been identified as a key driver in gastroesophageal reflux disease, cancer of the lower esophagus, and aspiration-induced lung complications. Due to the large population burden and significant morbidity and mortality related to reflux barrier dysfunction, there is a pressing need to develop tissue engineering solutions which can replace diseased junctions. While good progress has been made in engineering the bodies of the esophagus and stomach, little has been done for the junction between the two. In this review, we discuss pertinent topics which should be considered as tissue engineers begin to address this anatomical region. The embryological development and adult anatomy and histology are discussed to provide context about the native structures which must be replicated. The roles of smooth muscle structures in the esophagus and stomach, as well as the contribution of the diaphragm to normal anti-reflux function are then examined. Finally, engineering considerations including mechanics and current progress in the field of tissue engineering are presented.

Prospective serial diagnostic study: the effects of position and provocative tests on the diagnosis of oesophageal motility disorders by high-resolution manometry

BACKGROUND

Standard high-resolution manometry (HRM) protocols are based on 10 single water swallows acquired in the supine position.

AIMS

To assess the impact of position, rapid drink challenge and solid test meal on the diagnosis of oesophageal motility disorders.

METHODS

Seventy-two healthy volunteers (20-76 years) and 366 consecutive patients (18-90 years) completed HRM with 10 single water swallows in the supine and upright positions. Rapid drink challenge was performed twice, before and after the solid test meal. Diagnosis based on single water swallows in the supine position (Chicago Classification v3.0) was compared with results in the upright position and with provocative tests.

RESULTS

Overall, diagnostic agreement in the supine and upright positions was present in 296/438 (67.6%) subjects. This increased to 90.0% when ineffective oesophageal motility was considered with normal motility. Integrated relaxation pressure was 4 mm Hg higher in the supine position. There was a higher prevalence of inconsistent, likely false positive, diagnoses of outlet obstruction in the supine compared to the upright position (16/20 vs 1/4 patients, P = 0.0007). Similarly, the difference in concordance for the diagnosis of oesophago-gastric junction obstruction or achalasia between single water swallows in the supine and upright positions with solid test meal was significant (12/29 (41.4%) vs 12/14 (85.7%), P = 0.0087).

CONCLUSION

Diagnostic agreement for oesophageal motility disorders based on single water swallows in the upright and supine positions was moderate, with frequent discordant findings for ineffective motility and outlet obstruction. HRM studies can be performed in either position, using appropriate reference values. Rapid drink challenge or solid test meal can resolve diagnostic discrepancies.

Innovations in Endoscopic Therapy for Gastroesophageal Reflux Disease

Minimally invasive endoscopic antireflux therapies are critical for bridging the gap between medical and surgical treatments for gastroesophageal reflux disease (GERD). Although multiple endoscopic devices have been developed, perhaps some of the most exciting options that are currently evolving are the full-thickness suturing techniques using widely available and low-cost platforms. Full-thickness endoscopic suturing can allow for a highly durable recreation of the anatomic and functional components of a lower esophageal sphincter, which are deficient in patients with GERD. Proper patient selection, endoscopic hiatal hernia evaluation, and standardized suturing methods are necessary to ensure success of endoscopic suturing for antireflux therapy.

Use of Bioelectronics in the Gastrointestinal Tract

Gastrointestinal (GI) motility disorders are major contributing factors to functional GI diseases that account for >40% of patients seen in gastroenterology clinics and affect >20% of the general population. The autonomic and enteric nervous systems and the muscles within the luminal GI tract have key roles in motility. In health, this complex integrated system works seamlessly to transport liquid, solid, and gas through the GI tract. However, major and minor motility disorders occur when these systems fail. Common functional GI motility disorders include dysphagia, gastroesophageal reflux disease, functional dyspepsia, gastroparesis, chronic intestinal pseudo-obstruction, postoperative ileus, irritable bowel syndrome, functional diarrhea, functional constipation, and fecal incontinence. Although still in its infancy, bioelectronic therapy in the GI tract holds great promise through the targeted stimulation of nerves and muscles.

First Experience with Banded Anti-reflux Mucosectomy (ARMS) for GERD: Feasibility, Safety, and Technique (with Video)

BACKGROUND

Anti-reflux mucosectomy (ARMS) is a relatively new endoscopic procedure for gastroesophageal reflux disease (GERD). A hemi-circumferential endoscopic mucosal resection (EMR) is performed around the gastroesophageal junction (GEJ), which then contracts and tightens during healing. The aim of this study was to assess the feasibility and safety of the procedure. A secondary aim was to assess short-term outcomes on PPI use and symptom resolution.

METHODS

IRB approval was obtained for retrospective review of a prospectively collected database including patients who underwent ARMS during a 2-year period. To be eligible for the procedure, patients required medically refractory GERD and a hiatal hernia no more than 2 cm. A 270-degree mucosal resection of the gastric cardia was performed in a retroflexed position using a multi-band EMR system. Demographics, preoperative workup, intraoperative factors, additional procedures, and other follow-up were collected by chart review. Voluntary validated surveys assessed symptomatic improvement over time.

RESULTS

There were 19 patients available for review. The procedure was technically completed in all cases. There was one muscle injury due to a deep resection that was repaired by endoscopic suturing. All patients were discharged on the day of the procedure. Early dysphagia was experienced by three patients (16%) which was addressed with endoscopic balloon dilation. GERD symptoms improved in 13 patients (68%) after discontinuing PPI therapy. Three of the six failures went on to have additional anti-reflux surgery. Among patients who did not have additional surgery, quality of life data showed significant symptomatic improvement by 6 months.

CONCLUSION

In this ARMS case series, the procedure was technically successful in all patients with only one minor complication. Two thirds of patients showed symptomatic improvement and were able to discontinue their PPI. ARMS appears to be a safe procedure that does not hinder future laparoscopic anti-reflux surgery in case of failure. Additional tuning of technique and postoperative management may be able to reduce dysphagia rates and the need for dilation.

Measuring length-tension function of the anal sphincters and puborectalis muscle using the functional luminal imaging probe

The functional luminal imaging probe (FLIP) has been used to measure the distensibility of the anal canal. We hypothesized that with increasing distension of the anal canal with FLIP there will be an increase in length of the anal sphincter muscle allowing measurement of the length-tension function of anal sphincter and puborectalis muscles (PRM). We studied 14 healthy nulliparous women. A custom-designed FLIP bag (30-mm diameter) was placed in the vagina and then in the anal canal, distended in 10-ml steps with volumes ranging from 30 to 90 ml. At each volume, subject performed maximal voluntary squeezes. Length-tension measurements were also made with a manometric probe system. Tension was calculated (pressure × radius) in Newtons per meter using a custom software program. Peak tensions at different FLIP volumes were compared with the manometric data. No change in the luminal CSA was noted at low fluid volumes; the sphincter muscles were able to fully collapse the FLIP bag within the anal canal/vagina even at rest. At larger volumes, with each squeeze there was an increase in the bag pressure and reduction in the cross-sectional area, which represents concentric contraction of the muscle. Both rest and squeeze tension increased with the increase in volume in the anal as well as vaginal canal indicating that the external anal sphincter and puborectalis muscles produce more tension when lengthened. FLIP device, which has been used to describe the distensibility of the anal canal can also provide information on the length-tension function of the anal sphincters and PRM. NEW & NOTEWORTHY The functional luminal imaging probe (FLIP) has been used to describe the distensibility of the anal canal. This report is the first to describe the use of the FLIP in the vaginal canal and the anal canal to provide information on the length-tension function of the anal sphincter and puborectalis muscles, which may provide clinicians with additional information regarding the active components of muscle contraction involved in the anal closure function.

Studies of abnormalities of the lower esophageal sphincter during esophageal emptying based on a fully coupled bolus-esophageal-gastric model

The aim of this work was to develop a fully coupled bolus-esophageal-gastric model based on the immersed boundary-finite element method to study the process of esophageal emptying across the esophagogastric junction (EGJ). The model included an esophageal segment, an ellipsoid-shaped stomach, a bolus, and a simple model of the passive and active sphincteric functions of the lower esophageal sphincter (LES). We conducted three sets of case studies: (1) the effect of a non-relaxing LES; (2) the influence of the tissue anisotropy in the form of asymmetrical right- and left-sided compliance of the LES segment; and (3) the influence of LES and gastric wall stiffness on bulge formation of the distal esophageal wall. We found that a non-relaxing LES caused sustained high wall stress along the LES segment and obstruction of bolus emptying. From the simulations of tissue anisotropy, we found that the weaker side (i.e., more compliant) of the LES segment sustained greater deformation, greater wall shear stress, and a greater high-pressure load during bolus transit. In the third set of studies, we found that a right-sided bulge in the esophageal wall tends to develop during esophageal emptying when LES stiffness was decreased or gastric wall stiffness was increased. Hence, the bulge may be partly due to the asymmetric configuration of the gastric wall with respect to the esophageal tube. Together, the observations from these simulations provide insight into the genesis of epiphrenic diverticula, a complication observed with esophageal motility disorders. Future work, with additional layers of complexity to the model, will delve into the mechanics of gastroesophageal reflux and the effects of hiatus hernia on EGJ function.

Initial experience with a novel resection and plication (RAP) method for acid reflux: a pilot study

BACKGROUND AND STUDY AIMS

 Current endoscopic therapies for gastroesophageal reflux disorder (GERD) are limited by technical complexity, and/or cost. We sought to evaluate the success of a novel resection and plication (RAP) anti-reflux procedure.

PATIENTS AND METHODS

 RAP was performed on 10 patients with GERD refractory to proton pump inhibitor (PPI) therapy. RAP consists of semi-circumferential mucosectomy along with full-thickness plication of the lower esophageal sphincter (LES) and cardia. We assessed the technical success and safety as well as followed GERD-Health Related Quality of Life (GERD-HRQL) scores and medication usage.

RESULTS

All patients underwent RAP without adverse events and were discharged on the same day. Only half of the patients required general anesthesia. Follow-up ranged from 5 to 24 months (median 9 months) and all patients had a significant improvement in their GERD-HRQL scores ( P  < 0.0001, 95 % CI 19.3 - 25.3). 8 of 10 eliminated their daily PPI dependence.

CONCLUSIONS

 The RAP method has potential as an effective anti-reflux option. Its main advantages include a short procedure time, simple approach using readily available equipment, and possible avoidance of general anesthesia.

Three-Dimensional Myoarchitecture of the Lower Esophageal Sphincter and Esophageal Hiatus Using Optical Sectioning Microscopy

Studies to date have failed to reveal the anatomical counterpart of the lower esophageal sphincter (LES). We assessed the LES and esophageal hiatus morphology using a block containing the human LES and crural diaphragm, serially sectioned at 50 μm intervals and imaged at 8.2 μm/pixel resolution. A 3D reconstruction of the tissue block was reconstructed in which each of the 652 cross sectional images were also segmented to identify the boundaries of longitudinal (LM) and circular muscle (CM) layers. The CM fascicles on the ventral surface of LES are arranged in a helical/spiral fashion. On the other hand, the CM fascicles from the two sides cross midline on dorsal surface and continue as sling/oblique muscle on the stomach. Some of the LM fascicles of the esophagus leave the esophagus to enter into the crural diaphragm and the remainder terminate into the sling fibers of the stomach. The muscle fascicles of the right crus of diaphragm which form the esophageal hiatus are arranged like a “noose” around the esophagus. We propose that circumferential squeeze of the LES and crural diaphragm is generated by a unique myo-architectural design, each of which forms a “noose” around the esophagus.

Functional morphology of the lower esophageal sphincter and crural diaphragm determined by three-dimensional high-resolution esophago-gastric junction pressure profile and CT imaging

The smooth muscles of the lower esophageal sphincter (LES) and skeletal muscles of the crural diaphragm (CD) provide a closure/antireflux barrier mechanism at the esophago-gastric junction (EGJ). A number of questions in regard to the pressure profile of the LES and CD remain unclear, e.g., 1) Why is the LES pressure profile circumferentially asymmetric, 2) Is the crural diaphragm (CD) contraction also circumferentially asymmetric, and 3) Where is the LES and CD pressure profile located in the anatomy of the esophagus and stomach? The three-dimensional (3-D) high-resolution esophageal manometry (HRM) catheter can record a detailed profile of the EGJ pressure; however, it does not allow the determination of the circumferential orientation of individual pressure transducers in vivo. We used computed tomography (CT) scan imaging in combination with 3-D EGJ pressure recordings to determine the functional morphology of the LES and CD and its relationship to the EGJ anatomy. A 3-D-HRM catheter with 96 transducers (12 rings, 7.5 mm apart, located over 9-cm length of the catheter, with eight transducers in each ring, 45° apart (Medtronics), was used to record the EGJ pressure in 10 healthy subjects. A 0.5-mm diameter metal ball (BB) was taped to the catheter, adjacent to transducer 1 of the catheter. The EGJ was recorded under the following conditions: 1) end-expiration (LES pressure) before swallow, after swallow, and after edrophonium hydrochloride; and 2) peak inspiration (crural diaphragm contraction) for tidal inspiration and forced maximal inspiration. A CT scan was performed to localize the circumferential orientation of the BB. The CT scan imaging allowed the determination of the circumferential orientation of the LES and CD pressure profiles. The LES pressure under the three end-expiration conditions were different; however, the shape of the pressure profile was unique with the LES length longer toward the lesser curvature of the stomach as compared with the greater curvature. The pressure profile revealed circular and axial pressure asymmetry, with greatest pressure and shortest cranio-caudal length on the left (close to the angle of His). The CD contraction with tidal and forced inspiration increases pressure in the cranial half of the LES pressure profile, and it was placed horizontally across the recording. The CD, esophagus, and stomach were outlined in the CT scan images to construct a 3-D anatomy of the region; it revealed that the hiatus (CD) is placed obliquely across the esophagus; however, because of the bend of the esophagus to the left at the upper edge of the hiatus, the two were placed at right angle to each other, which resulted in a horizontal pressure profile of the CD on the LES. Our observations suggest a unique shape of the LES, CD, and the anatomical relationship between the two, which provides a possible explanation as to why the LES pressure shows circumferential and axial asymmetry. Our findings have implication for the length and circumferential orientation of myotomy incision required for the ablation of LES pressure in achalasia esophagus.NEW & NOTEWORTHY We used computed tomography scan imaging with three-dimensional esophago-gastric junction (EGJ) pressure recordings to determine functional morphology of the lower esophageal sphincter (LES) and crural diaphragm and its relationship to EGJ anatomy. The LES pressure profile was unique with the LES length longer and pressures lower toward the lesser curvature of the stomach, as compared with the greater curvature. Our findings have implications for the length and circumferential orientation of myotomy incision required for the ablation of LES pressure in the achalasia esophagus.

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.

The Esophagiome: concept, status, and future perspectives

The term "Esophagiome" is meant to imply a holistic, multiscale treatment of esophageal function from cellular and muscle physiology to the mechanical responses that transport and mix fluid contents. The development and application of multiscale mathematical models of esophageal function are central to the Esophagiome concept. These model elements underlie the development of a "virtual esophagus" modeling framework to characterize and analyze function and disease by quantitatively contrasting normal and pathophysiological function. Functional models incorporate anatomical details with sensory-motor properties and functional responses, especially related to biomechanical functions, such as bolus transport and gastrointestinal fluid mixing. This brief review provides insight into Esophagiome research. Future advanced models can provide predictive evaluations of the therapeutic consequences of surgical and endoscopic treatments and will aim to facilitate clinical diagnostics and treatment.

Normal and abnormal physiology, pharmacology, and anatomy of the gastroesophageal junction high-pressure zone

The high-pressure zone of the gastroesophageal junction acts as a multifunctional valve that comprises different groups of smooth muscles located in the distal esophagus and the proximal stomach, in addition to the extrinsic crural diaphragm, composed of skeletal muscle. In this review article, we evaluate the current literature with respect to human subjects, discussing the anatomic locations and physiologic and pharmacologic processes controlling these muscles. These muscles work individually and as a group to prevent reflux of gastric contents while allowing anterograde passage of food and liquid and retrograde passage of gas. We also reviewed new findings with respect to abnormalities that are permissive of reflux of gastric contents into the esophagus, which may lead to gastroesophageal reflux disease.

Qualitative evaluation of osteopathic manipulative therapy in a patient with gastroesophageal reflux disease: a brief report

CONTEXT

Gastroesophageal reflux disease (GERD) is a chronic condition that affects a growing number of people and is currently among the most common disorders seen in clinical practice.

OBJECTIVE

To develop a protocol for the management of GERD with osteopathic manipulative therapy (OMTh) applied to the diaphragm and esophagus, and to evaluate the protocol's effectiveness using the quality of life scale (QS-GERD) for the disease.

METHODS

In this single-blinded prospective study, an OMTh protocol focusing on the diaphragm and esophagus was applied to a single patient, who had received a diagnosis of GERD 4 years previously. Outcomes were measured using the QS-GERD, which has a total possible score ranging from 0 to 45 (the lower the score, the better the quality of life) and a level of satisfaction from very satisfied to incapacitated. The OMTh protocol was applied at 3 sessions (initial session, second session 1 week after the first, and third session 2 weeks after the second), and the patient completed the QS-GERD 4 times (before the first session, before the third session, and 2 and 4 weeks after the third session).

RESULTS

The OMTh protocol was administered without adverse events, and the patient reported positive outcomes after the third session. The QS-GERD showed a score improvement from 13 of 45 to 4 of 45.

CONCLUSION

The results in the present report show that OMTh applied to the diaphragm and esophagus may improve symptoms of GERD and should be added to the somatovisceral approach to the care of patients with this condition.

Minimal vs. maximal esophageal dissection and mobilization during laparoscopic fundoplication: long-term follow-up from a prospective, randomized trial

PURPOSE

We have previously conducted a prospective randomized trial (PRT) comparing circumferential phrenoesophageal dissection and esophageal mobilization (MAX) to minimal dissection/mobilization (MIN). The MIN group had a decreased incidence of postoperative wrap herniation and need for reoperation. This study provides long-term follow-up of the patients from our center who participated in the PRT.

METHODS

Parents of patients in the PRT were queried regarding symptoms, medication use, postoperative complications, and additional procedures. Medical records were reviewed. Student's t-test was used for continuous variables. Fisher's exact and chi-square with Yates correction were used where appropriate.

RESULTS

Of patients from our center, 75.4% MAX and 72.5% MIN patients were contacted. Median time to follow-up was 6.5 years. A rise in the incidence of herniation was noted in both groups (22.7% to 36.5% MAX vs 2.8% to 12.2% MIN). Time to diagnosis of hernia was significantly longer in the MIN group (14.7±9.5 months MAX vs 30.2±23.6 months MIN, P=0.04). There was no significant difference between MIN and MAX group in reflux symptoms or medication use.

CONCLUSION

Long-term follow-up demonstrates an increase in incidence of herniation in both groups. Previously demonstrated higher risk of wrap herniation with maximal esophageal dissection during laparoscopic fundoplication remains supporting original findings.

Effects of baclofen on the functional anatomy of the oesophago-gastric junction and proximal stomach in healthy volunteers and patients with GERD assessed by magnetic resonance imaging and high-resolution manometry: a randomised controlled double-blind study

BACKGROUND

The mechanism of reflux protection may involve a 'flap valve' at the oesophago-gastric junction (OGJ).

AIM

To assess the effects of baclofen, a gamma-aminobutyric acid receptor type-B (GABA-B) agonist known to suppress reflux events, on the 'functional anatomy' of the OGJ and proximal stomach after a large test meal.

METHODS

Twelve healthy volunteers (HVs) and 12 patients with gastro-oesophageal reflux disease (GERD); with erosive oesophagitis or pathological oesophageal acid exposure completed a randomised, double-blind, cross-over study. On 2 test days participants received 40-mg baclofen or placebo before ingestion of a large test meal. OGJ structure and function were assessed by high-resolution manometry (HRM) and magnetic resonance imaging (MRI) using validated methods. Measurements of the oesophago-gastric angle were derived from three-dimensional models reconstructed from anatomic MRI images. Cine-MRI and HRM identified postprandial reflux events. Mixed model analysis and Wilcoxon rank signed tests assessed differences between participant groups and treatment conditions.

RESULTS

In both HVs and GERD patients, baclofen reduced the frequency of postprandial reflux events. The oesophago-gastric insertion angle in GERD patients was reduced (-4.1 ± 1.8, P = 0.025), but was unchanged in healthy controls. In both study groups, baclofen augmented lower oesophageal sphincter (LES) pressure (HVs: +7.3 ± 1.8 mmHg, P < 0.0001, GERD: +4.50 ± 1.49 mmHg, P < 0.003) and increased LES length (HVs: +0.48 ± 0.11 cm, P < 0.0003, GERD: +0.35 ± 0.06 cm, P < 0.0001).

CONCLUSIONS

Baclofen inhibits transient LES relaxations and augments LES pressure and length. Additionally, baclofen has effects on the 'functional anatomy' of the OGJ and proximal stomach in GERD patients, which may suppress reflux by means of a 'flap valve' mechanism.

Nicotinic receptor subtypes mediating relaxation of the normal human clasp and sling fibers of the upper gastric sphincter

BACKGROUND

Proper function of the gastro-esophageal high pressure zone is essential for the integrity of the antireflux barrier. Mechanisms include tonic contractions and the decreased tone during transient lower esophageal sphincter relaxations.

METHODS

We characterized the pharmacology of nicotinic receptors mediating relaxations of the human upper gastric sphincter (clasp and sling fibers) using currently available subtype selective nicotinic antagonists in tissue from organ transplant donors. Donors with either a history of gastro-esophageal reflux disease or histologic evidence of Barrett's esophagus were excluded. Clasp and sling muscle fiber strips were used for one of three paradigms. For paradigm 1, each strip was exposed to carbachol, washed, exposed to nicotinic antagonists then re-exposed to carbachol. In paradigm 2, strips were exposed to a near maximally effective bethanechol concentration then nicotine was added. Strips then were washed, exposed to nicotinic antagonists then re-exposed to bethanechol followed by nicotine. In paradigm 3, strips were exposed to bethanechol then choline or cytisine.

KEY RESULTS

100 μM methyllycaconitine has no inhibitory effects on relaxations, eliminating homomeric α7 subtypes. Subtypes composed of α4β2 subunits are also eliminated because choline acts as an agonist and dihydro-beta-erythroidine is ineffective.

CONCLUSIONS & INFERENCES

Because mecamylamine blocks the relaxations and both choline and cytisine act as agonists in both clasp and sling fibers, the nicotinic receptor subtypes responsible for these relaxations could be composed of α3β4β2, α2β4, or α4β4 subunits.

Abnormal structure and function of the esophagogastric junction and proximal stomach in gastroesophageal reflux disease

OBJECTIVES

This study applies concurrent magnetic resonance imaging (MRI) and high-resolution manometry (HRM) to test the hypothesis that structural factors involved in reflux protection, in particular, the acute insertion angle of the esophagus into the stomach, are impaired in gastroesophageal reflux disease (GERD) patients.

METHODS

A total of 24 healthy volunteers and 24 patients with mild-moderate GERD ingested a test meal. Three-dimensional models of the esophagogastric junction (EGJ) were reconstructed from MRI images. Measurements of the esophagogastric insertion angle, gastric orientation, and volume change were obtained. Esophageal function was assessed by HRM. Number of reflux events and EGJ opening during reflux events were assessed by HRM and cine-MRI. Statistical analysis applied mixed-effects modeling.

RESULTS

The esophagogastric insertion angle was wider in GERD patients than in healthy subjects (+7° ± 3°; P=0.03). EGJ opening during reflux events was greater in GERD patients than in healthy subjects (19.3 mm vs. 16.8 mm; P=0.04). The position of insertion and gastric orientation within the abdomen were also altered (both P<0.05). Median number of reflux events was 3 (95% CI: 2.5-4.6) in GERD and 2 (95% CI: 1.8-3.3) in healthy subjects (P=0.09). Lower esophageal sphincter (LES) pressure was lower (-11 ± 2 mm Hg; P<0.0001) and intra-abdominal LES length was shorter (-1.0 ± 0.3 cm, P<0.0006) in GERD patients.

CONCLUSIONS

GERD patients have a wider esophagogastric insertion angle and have altered gastric morphology; structural changes that could compromise reflux protection by the "flap valve" mechanism. In addition, the EGJ opens wider during reflux in GERD patients than in healthy volunteers: an effect that facilitates volume reflux of gastric contents.

Enhanced nicotinic receptor mediated relaxations in gastroesophageal muscle fibers from Barrett's esophagus patients

BACKGROUND

Increased nicotinic receptor mediated relaxation in the gastroesophageal antireflux barrier may be involved in the pathophysiology of reflux. This study is designed to determine whether the defects we previously identified in gastroesophageal reflux disease patients in- vivo are due to abnormalities of the gastric sling, gastric clasp, or lower esophageal circular (LEC) muscle fibers.

METHODS

Muscle strips from whole stomachs and esophagi were obtained from 16 normal donors and 15 donors with histologically proven Barrett's esophagus. Contractile and relaxant responses of gastric sling, gastric clasp, or LEC fibers were determined to increasing concentrations of carbachol and to nicotine after inducing maximal contraction to bethanechol. Muscarinic receptor density was measured using subtype selective immunoprecipitation.

KEY RESULTS

Barrett's esophagus gastric sling and LEC fibers have decreased carbachol-induced contractions. Barrett's esophagus sling fibers have decreased M2 -muscarinic receptors and LEC fibers have decreased M3 receptors. Relaxations of all three fiber types are greater in Barrett's esophagus specimens to both high carbachol concentrations and to nicotine following bethanechol precontraction. The maximal response to bethanechol is greater in Barrett esophagus sling and LEC fibers.

CONCLUSIONS & INFERENCES

The increased contractile response to bethanechol in Barrett's specimens indicates that the defect is likely not due to the smooth muscle itself. The enhanced nicotinic receptor mediated response may be involved in greater relaxation of the muscles within the high-pressure zone of the gastroesophageal junction during transient lower esophageal sphincter relaxations and during deglutitive inhibition and may be involved in the pathophysiology of gastroesophageal reflux disease.

Physiology of the upper segment, body, and lower segment of the esophagus

The following discussion on the physiology of the esophagus includes commentaries on the function of the muscularis mucosa and submucosa as a mechanical antireflux barrier in the esophagus; the different mechanisms of neurological control in the esophageal striated and smooth muscle; new insights from animal models into the neurotransmitters mediating lower esophageal sphincter (LES) relaxation, peristalsis in the esophageal body (EB), and motility of esophageal smooth muscle; differentiation between in vitro properties of the lower esophageal circular muscle, clasp muscle, and sling fibers; alterations in the relationship between pharyngeal contraction and relaxation of the upper esophageal sphincter (UES) in patients with dysphagia; the mechanical relationships between anterior hyoid movement, the extent of upper esophageal opening, and aspiration; the application of fluoroscopy and manometry with biomechanics to define the stages of UES opening; and nonpharmacological approaches to alter the gastroesophageal junction (GEJ).

Vagal afferent innervation of the lower esophageal sphincter

To supply a fuller morphological characterization of the vagal afferents innervating the lower esophageal sphincter (LES), specifically to label vagal terminals in the tissues forming the LES in the gastroesophageal junction, the present experiment employed injections of dextran biotin into the nodose ganglia of rats. Four types of vagal afferents innervated the LES. Clasp and sling muscle fibers were directly and prominently innervated by intramuscular arrays (IMAs). Individual IMA terminals subtended about 16° of arc of the esophageal circumference, and, collectively, the terminal fields were distributed within the muscle ring to establish a 360° annulus of mechanoreceptors in the sphincter wall. 3D morphometry of the terminals established that, compared to sling muscle IMAs, clasp muscle IMAs had more extensive arbors and larger receptive fields. In addition, at the cardia, local myenteric ganglia between smooth muscle sheets and striated muscle bundles were innervated by intraganglionic laminar endings (IGLEs), in a pattern similar to the innervation of the myenteric plexus throughout the stomach and esophagus. Finally, as previously described, the principle bundle of sling muscle fibers that links LES sphincter tissue to the antropyloric region of the lesser curvature was innervated by exceptionally long IMAs as well as by unique web ending specializations at the distal attachment of the bundle. Overall, the specialized varieties of densely distributed vagal afferents innervating the LES underscore the conclusion that these sensory projections are critically involved in generating LES reflexes and may be promising targets for managing esophageal dysfunctions.

The effect of rabeprazole on LES tone in experimental rat model

INTRODUCTION

Despite adequate treatment with proton pump inhibitors (PPIs), symptoms of gastroesophageal reflux disease (GERD) may remain persistent as well as Barrett's esophagus may emerge. It may be proposed that the relaxant effect of PPIs on the smooth muscles may lead to resistance of symptoms. The aim of this study is to investigate effects of rabeprazole on the lower esophageal sphincter (LES) pressure with a rat model.

MATERIALS AND METHODS

Sixteen rats were grouped as control and treatment groups. After obtaining LES tissues followed by a 60 min equilibration period for stabilization, contractile response to carbachol was obtained by application of single dose of carbachol to have a final concentration of 10(-6) M in the organ bath. After the contractions reached a plateau, concentration-response relationships for rabeprazole were obtained in a cumulative manner in the treatment group.

RESULTS

In the carbachol contracted LES preparations; 1.5 × 10(-6) and 1.5×10(-5) M of rabeprazole caused 6.08% and 11.34% relaxations respectively which were not statistically significant. However, mean integral relaxation value for 4.5 × 10(-5) M of rabeprazole was 17.34% and this relaxation was significant compared with controls.

CONCLUSIONS

In the present study, rabeprazole caused no direct significant change in LES tone in the therapeutic dose range applied to the organ bath. However, rabeprazole at the high dose caused a significant decrease in the LES tone.

Characterization of the distal esophagus high-pressure zone with manometry, ultrasound and micro-computed tomography

BACKGROUND

We sought to determine how the individual components of the distal esophagus and proximal stomach form the gastroesophageal junction high-pressure zone (GEJHPZ) antireflux barrier.

METHODS

An endoscopic ultrasound/manometry catheter was pulled through the proximal stomach and distal esophagus in 20 normal subjects. The axial length and width of individual structures on endoscopic ultrasound were measured. The anatomic orientation of gastroesophageal junction (GEJ) components was examined in two organ donor specimens using micro-computed tomography (micro-CT).

KEY RESULTS

The three distinct structures identified within the GEJHPZ, from distal to proximal, were as follows: the gastric clasp and sling muscle fiber complex, crural diaphragm, and lower esophageal circular smooth muscle fibers (LEC). The LEC was statistically significantly thicker than adjacent esophageal muscles. These structures were associated with three pressure peaks. The pressure peak produced by the clasp/sling fiber complex often overlapped with the pressure peak from the crural diaphragm. The most proximal peak, associated with the LEC, was significantly greater and bimodal in nine of 20 subjects. This bimodal LEC pressure peak correlated with two areas of thickened muscle observed with ultrasound. Micro-CT of GEJ from organ donors confirmed the two areas of thickened muscle.

CONCLUSIONS & INFERENCES

Three distinct anatomic structures, the clasp and sling muscle fibers, crural diaphragm, and LEC combine to form the antireflux barrier of the proximal stomach and distal esophagus. The clasp and sling muscle fibers combine with the crural diaphragm to form a distal pressure profile. The more proximal LEC has a bimodal pressure profile in some patients.

Slow esophageal propagation velocity: association with dysphagia for solids

BACKGROUND

Spastic disorders of the esophagus, associated with rapid esophageal propagation velocity, are classically associated with dysphagia and/or chest pain. The aim of this study was to characterize patients with slow esophageal propagation velocity (SPV) on high-resolution esophageal manometry (HRM).

METHODS

A review of patients undergoing HRM was conducted during 1-year study period. Patients with achalasia, aperistalsis, and diffuse esophageal spasm were excluded. Patients with contractile front velocity (CFV) ≤ 2.3 cm s(-1) were defined as having SPV, whereas normal propagation velocity (NPV) was defined as ≥ 2.6 cm s(-1). A composite isobaric contour of all swallows for each patient was generated to determine composite distal contraction latency (cDL).

KEY RESULTS

A total of 650 HRMs were reviewed and 552 met inclusion criteria. 173 patients had SPV and 339 had NPV. There was a greater female predominance in the SPV group compared with NPV (75.7%vs 66.4%, P = 0.03). Patients in the SPV group reported more dysphagia for solids (66.3%vs 53.3%; P = 0.004) and nausea (68.6%vs 59.0%; P = 0.04) than NPV group. Dysphagia for solids was the only symptom significantly associated with SPV group (OR = 2.21, CI = 1.21-4.02; P = .01). There was a negative correlation between CFV and cDL, r = -0.494, P < 0.001.

CONCLUSIONS & INFERENCES

Patients with SPV have a higher prevalence of dysphagia for solids and nausea when compared with NPV. Dysphagia for solids was the only symptom significantly associated with SPV group. Thus, abnormal esophageal propagation velocity (both slow and rapid) is associated with dysphagia.

Vagal sensory innervation of the gastric sling muscle and antral wall: implications for gastro-esophageal reflux disease?

BACKGROUND

The gastric sling muscle has not been investigated for possible sensory innervation, in spite of the key roles the structure plays in lower esophageal sphincter (LES) function and gastric physiology. Thus, the present experiment used tracing techniques to label vagal afferents and survey their projections in the lesser curvature.

METHODS

Sprague-Dawley rats received injections of dextran biotin into the nodose ganglia. Fourteen days postinjection, animals were euthanized and their stomachs were processed to visualize the vagal afferent innervation. In different cases, neurons, muscle cells, or interstitial cells of Cajal (ICC) were counterstained.

KEY RESULTS

The sling muscle is innervated throughout its length by vagal afferent intramuscular arrays (IMAs) associated with ICC. In addition, the distal antral attachment site of the sling muscle is innervated by a novel vagal afferent terminal specialization, an antral web ending. The muscle wall of the distal antrum is also innervated by conventional IMAs and intraganglionic laminar endings, the two types of mechanoreceptors found throughout stomach smooth muscle.

CONCLUSIONS & INFERENCES

The innervation of sling muscle by IMAs, putative stretch receptors, suggests that sling sensory feedback may generate vago-vagal or other reflexes with vagal afferent limbs. The restricted distribution of afferent web endings near the antral attachments of sling fibers suggests the possibility of specialized mechanoreceptor functions linking antral and pyloric activity to the operation of the LES. Dysfunctional sling afferents could generate LES motor disturbances, or normative compensatory sensory feedback from the muscle could compromise therapies targeting only effectors.

The gastro-esophageal reflux barrier: biophysical analysis on 3D models of anatomy from magnetic resonance imaging

BACKGROUND

The function and structure of the gastro-esophageal junction (GEJ) determine its efficacy as a reflux barrier. This study presents a novel methodology for the quantitative assessment of GEJ and proximal gastric morphology from magnetic resonance (MR) imaging. Based on this data we propose a new conceptualization of the hypothesis that a flap valve mechanism contributes to reflux protection.

METHODS

3D models of the GEJ and proximal stomach were reconstructed from MR images in 12 healthy volunteers during respiration and on eating a test meal to maximum satiation. A rotating plane analysis measured the gastro-esophageal insertion angle and span of contact. An ellipsoid fit provided quantitative assessment of gastric shape and orientation relative to a fixed anatomical reference point. Position of the esophageal insertion on the 'gastric ellipse' was noted. An ellipsoid-cylinder model was designed to analyze the relationships among parameters describing the GEJ morphology.

KEY RESULTS

The insertion angle became more acute on expiration, but did not change with meal ingestion. In contrast the span of contact did not vary with respiration, but increased with gastric filling. Changes in gastric morphology with distension further augmented the span of gastro-esophageal contact in almost 70% of the studies.

CONCLUSIONS & INFERENCES

Novel MR imaging and biophysical analysis of the GEJ and proximal stomach provide a quantitative description of structures contributing to the reflux barrier. Changes in these parameters during respiration and on eating support the hypothesis that structural components of a functional 'flap valve' like mechanism contribute to reflux protection.

Physiology of the LES

The purpose of this review is to consider the neuromuscular mechanism of LES contractility both by itself and in relation to the esophagogastric junction (EGJ) complex in order to appreciate the intricacies of EGJ valvular function.

Pressure morphology of the relaxed lower esophageal sphincter: the formation and collapse of the phrenic ampulla

This study aimed to apply novel high-resolution manometry with eight-sector radial pressure resolution (3D-HRM technology) to resolve the deglutitive pressure morphology at the esophagogastric junction (EGJ) before, during, and after bolus transit. A hybrid HRM assembly, including a 9-cm-long 3D-HRM array, was used to record EGJ pressure morphology in 15 normal subjects. Concurrent videofluoroscopy was used to relate bolus movement to pressure morphology and EGJ anatomy, aided by an endoclip marking the squamocolumnar junction (SCJ). The contractile deceleration point (CDP) marked the time at which luminal clearance slowed to 1.1 cm/s and the location (4 cm proximal to the elevated SCJ) at which peristalsis terminated. The phrenic ampulla spanned from the CDP to the SCJ. The subsequent radial and axial collapse of the ampulla coincided with the reconstitution of the effaced and elongated lower esophageal sphincter (LES). Following ampullary emptying, the stretched LES (maximum length 4.0 cm) progressively collapsed to its baseline length of 1.9 cm (P < 0.001). The phrenic ampulla is a transient structure comprised of the stretched, effaced, and axially displaced LES that serves as a "yield zone" to facilitate bolus transfer to the stomach. During ampullary emptying, the LES circular muscle contracts, and longitudinal muscle shortens while that of the adjacent esophagus reelongates. The likely LES elongation with the formation of the ampulla and shortening to its native length after ampullary emptying suggest that reduction in the resting tone of the longitudinal muscle within the LES segment is a previously unrecognized component of LES relaxation.

Distensibility testing of the esophagus

The following contains commentaries on distensibility testing using the functional lumen imaging probe (FLIP); the use of the distention test of the esophageal body in the clinic diagnosis of noncardiac chest pain; the functional lumen imaging in gastroesophageal reflux disease-impaired esophagogastric junction; a multimodal pain model for the esophagus; the rationale for distensibility testing; and further developments in standardized distension protocols.

3D-high resolution manometry of the esophagogastric junction

BACKGROUND

The esophagogastric junction (EGJ) is a complex structure that challenges accurate manometric recording. This study aimed to define EGJ pressure morphology relative to the squamocolumnar junction (SCJ) during respiration with 3D-high resolution manometry (3D-HRM).

METHODS

A 7.5-cm long 3D-HRM array with 96 independent solid-state pressure sensors (axial spacing 0.75 cm, radial spacing 45°) was used to record EGJ pressure in 15 normal subjects. Concurrent videofluoroscopy was used to localize the SCJ marked with an endoclip. Ex vivo experiments were done on the effect of bending the probe to match that seen fluoroscopically.

KEY RESULTS

3D-high resolution manometry EGJ pressure recordings were dominated by an asymmetric pressure peak superimposed on the lower esophageal sphincter (LES) attributable to the crural diaphragm (CD). Median peak CD pressure at expiration and inspiration (51 and 119 mmHg, respectively) was much greater in 3D-HRM than evident in HRM with circumferential pressure averaging. Esophagogastric junction length, defined as the zone of circumferential pressure exceeding that of adjacent esophagus or stomach was also substantially shorter (2.4 cm) than evident in conventional HRM. No consistent circumferential EGJ pressure was evident distal to the SCJ in 3D-HRM recordings and ex vivo experiments suggested that the intra-gastric pressure peak seen contralateral to the CD related to bending the assembly rather than the sphincter per se.

CONCLUSIONS & INFERENCES

3D-high resolution manometry demonstrated a profoundly asymmetric and vigorous CD component to EGJ pressure superimposed on the LES. Esophagogastric junction length was shorter than evident with conventional HRM and the distal margin of the EGJ sphincteric zone closely correlated with the SCJ.

The esophagogastric junction

The following discussion of the esophagogastric junctions includes commentaries on the three component structures of the sphincteric segment between the stomach and the esophagus; the pressure contributions from the three sphincteric components in normal subjects and in gastroesophageal reflux (GERD) patients; the mechanism of action of endoscopic plication to determine the underlying pathophysiology of GERD; and in vitro muscle strip studies of defects within the gastroesophageal sphincteric segment potentially leading to GERD.

Pharmacologic specificity of nicotinic receptor-mediated relaxation of muscarinic receptor precontracted human gastric clasp and sling muscle fibers within the gastroesophageal junction

Relaxation of gastric clasp and sling muscle fibers is involved the transient lower esophageal sphincter relaxations underlying the pathophysiology of gastroesophageal reflux disease (GERD). These fibers do not contribute tone to the high-pressure zone in GERD patients, indicating their role in pathophysiology. This study identifies some mediators of the nicotine-induced relaxation of muscarinic receptor precontracted gastric clasp and sling fibers. Muscle strips from organ donors precontracted with bethanechol were relaxed with nicotine and then rechallenged after washing and adding inhibitors tetrodotoxin (TTX), the nitric-oxide synthase inhibitor L-nitro-arginine methyl ester (L-NAME), the β-adrenoceptor antagonist propranolol, the glycine receptor antagonist strychnine or ginkgolide B, and the GABA(A) receptor antagonist bicuculline or 2-(3-carboxypropyl)-3-amino-6-(4 methoxyphenyl)pyridazinium bromide [(gabazine) SR95531]. TTX only inhibited clasp fiber relaxations. L-NAME and propranolol inhibited, and ginkgolide B was ineffective in both. SR95531 was ineffective in clasp fibers and partially effective in sling fibers. Strychnine and bicuculline prevented relaxations with low potency, indicating actions not on glycine or GABA(A) receptors but more consistent with nicotinic receptor blockade. Bethanechol-precontracted fibers were relaxed by the nitric oxide donor S-nitroso-N-acetyl-DL-penicillamine and by the β-adrenergic agonist isoproterenol (clasp fibers only) but not by the glycine receptor agonist taurine or glycine or the GABA(A) agonist muscimol. These data indicate that nicotinic receptor activation mediates relaxation via release of nitric oxide in clasp and sling fibers, norepinephrine acting on β-adrenoceptors in clasp fibers, and GABA acting on GABA(A) receptors in sling fibers. Agents that selectively prevent these relaxations may be useful in the treatment of GERD.

Minimal vs extensive esophageal mobilization during laparoscopic fundoplication: a prospective randomized trial

PURPOSE

Laparoscopic Nissen fundoplication has been traditionally performed with extensive esophageal dissection to create 2 to 3 cm of intraabdominal esophagus. Retrospective data have suggested that minimal esophageal mobilization may reduce the risk of postoperative herniation of the wrap into the lower mediastinum. To compare complete esophageal dissection to leaving the phrenoesophageal attachment intact, we conducted a 2-center, prospective, randomized trial.

METHODS

After obtaining permission/assent, patients were randomized to circumferential division of the phrenoesophageal attachments (MAX) or minimal mobilization with no violation of the phrenoesophageal membrane (MIN). A contrast study was performed at 1 year. The primary outcome variable was postoperative wrap herniation.

RESULTS

One hundred seventy-seven patients were enrolled in the study (MIN, n = 90; MAX, n = 87) from February 2006 to May 2008. There were no differences in demographics or operative time. Contrast studies were performed in 64 MIN and 71 MAX patients, respectively. The transmigration rate was 30% in the MAX group compared with 7.8% in the MIN group (P = .002). The reoperation rate was 18.4% in the MAX group and 3.3% in the MIN group (P = .006)

CONCLUSIONS

Minimal esophageal mobilization during laparoscopic fundoplication decreases postoperative wrap transmigration and the need for a redo operation.

Comparison of human and porcine gastric clasp and sling fiber contraction by M2 and M3 muscarinic receptors

To compare the gastroesophageal junction of the human with the pig, M(2) and M(3) receptor densities and the potencies of M(2) and M(3) muscarinic receptor subtype selective antagonists were determined in gastric clasp and sling smooth muscle fibers. Total muscarinic and M(2) receptors are higher in pig than human clasp and sling fibers. M(3) receptors are higher in human compared with pig sling fibers but lower in human compared with pig clasp fibers. Clasp fibers have fewer M(3) receptors than sling fibers in both humans and pigs. Similar to human clasp fibers, pig clasp fibers contract significantly less than pig sling fibers. Analysis of the methoctramine Schild plot suggests that M(2) receptors are involved in mediating contraction in pig clasp and sling fibers. Darifenacin potency suggests that M(3) receptors mediate contraction in pig sling fibers and that M(2) and M(3) receptors mediate contraction in pig clasp fibers. Taken together, the data suggest that both M(2) and M(3) muscarinic receptors mediate the contraction in both pig clasp and sling fibers similar to human clasp and sling fibers.

Induced opening of the gastroesophageal junction occurs at a lower gastric pressure in gerd patients and in hiatal hernia subjects than in normal control subjects

Purpose. To determine intragastric pressure threshold for inducing gastroesophageal junction (GEJ) opening in normal control subjects with and without hiatal hernia, and in patients with gastroesophageal reflux disease. Methods. This study was performed in 13 normal volunteers, 5 volunteers with hiatal hernia, and 3 patients with gastroesophageal reflux disease. During endoscopy a pressure transducer was used to measure baseline gastric pressures. The pressure in the stomach was measured while air was insufflated into the stomach until the gastroesophageal junction opened on endoscopic view. Results. There were two patterns of GEJ opening in normal volunteers. The mean opening pressure for Gastroesophageal junction in normal pattern-I, normal pattern-II, hiatal hernia, and Gastroesophageal reflux patients was 11.5, 12.6, 3.4, and 1.3 mmHg, respectively. Conclusions. GEJ opening is induced at a significantly lower pressure in subjects with hiatal hernia and in patients with gastroesophageal reflux disease than in normal volunteers.

GABAB receptor agonism as a novel therapeutic modality in the treatment of gastroesophageal reflux disease

Defined pharmacologically by its insensitivity to the GABA(A) antagonist bicuculline and sensitivity to the GABA analogue baclofen, the G protein-linked gamma-aminobutyric acid type B (GABA(B)) receptor couples to adenylyl cyclase, voltage-gated calcium channels, and inwardly-rectifying potassium channels. On the basis of a wealth of preclinical data in conjunction with early clinical observations that baclofen improves symptoms of gastroesophageal reflux disease (GERD), the GABA(B) receptor has been proposed as a therapeutic target for a number of diseases including GERD. Subsequently, there has been a significant effort to develop a peripherally-restricted GABA(B) agonist that is devoid of the central nervous system side effects that are observed with baclofen. In this article we review the in vitro and in vivo pharmacology of the peripherally-restricted GABA(B) receptor agonists and the preclinical and clinical development of lesogaberan (AZD3355, (R)-(3-amino-2-fluoropropyl) phosphinic acid), a potent and predominately peripherally-restricted GABA(B) receptor agonist with a preclinical therapeutic window superior to baclofen.

A missing sphincteric component of the gastro-oesophageal junction in patients with GORD

It was recently shown that the tonic pressure contribution to the high-pressure zone of the oesophago-gastric segment (OGS) contains the contributions from three distinct components, two of which are smooth muscle intrinsic sphincter components, a proximal and a distal component [J Physiol 2007; 580.3: 961]. The aim of this study was to compare the pressure contributions from the three sphincteric components in normal subjects with those in gastro-oesophageal reflux disease (GORD) patients. A simultaneous endoluminal ultrasound and manometry catheter was pulled through the OGS in 15 healthy volunteers and seven patients with symptomatic GORD, before and after administration of atropine. Pre-atropine (complete muscle tone), postatropine (non-muscarinic muscle tone plus residual muscarinic tone) and subtracted (pure muscarinic muscle tone) pressure contributions to the sphincter were averaged after referencing spatially to the right crural diaphragm and the pull-through start position. In the normal group, the atropine-resistant and atropine-attenuated pressures identified the crural and two smooth muscle sphincteric components respectively. The subtraction pressure curve contained proximal and distal peaks. The proximal component moved with the crural sling between full inspiration and full expiration and the distal component coincided with the gastric sling-clasp fibre muscle complex. The subtraction curve in the GORD patients contained only a single pressure peak that moved with the crural sphincter, while the distal pressure peak of the intrinsic muscle component, which was previously recognized in the normal subjects, was absent. We hypothesize that the distal muscarinic smooth muscle pressure component (gastric sling/clasp muscle fibre component) is defective in GORD patients.