Surgical Anatomy of Paraesophageal Hernias.

Paraesophageal hernia represents a complex surgical problem involving significant distortion of the anatomy and function of the esophagus, stomach, gastroesophageal junction, mediastinum, lungs, and heart. Surgeons operating in the area must have deep understanding of the normal anatomy and pathologic derangements in patients with paraesophageal hernias. This article describes the normal anatomy and anatomic abnormalities in application to the various approaches used in the surgical repair of a paraesophageal hernia.

Impact of reflux esophagitis on the esophageal function before and after laparoscopic fundoplication.

BACKGROUND: High-resolution manometry (HRM), which is breakthrough testing equipment to evaluate esophageal motor function, was developed in Europe and United State and has garnered attention. Moreover, multichannel intraluminal impedance pH (MII-pH) testing has allowed us to grasp all liquid/gas reflux including not only acid but also non-acid reflux. We examined the impact of the presence of reflux esophagitis (RE) on esophageal motor function before and after laparoscopic fundoplication. MATERIALS AND METHODS: The subjects included 100 patients (male: 63 patients, mean age: 54.1 ± 15.8) among 145 patients who underwent laparoscopic fundoplication for GERD associated diseases during a 4-year period from October 2012 to September 2016, excluding 6 patients who underwent further surgery, 32 patients on whom HRM was not performed, 3 patients who had technical errors during testing, and 4 patients for whom the status of RE was unknown. Regarding HRM, Mano Scan from Given Imaging Ltd. was used, and for the analysis, Mano View version 3.0 from the same company was used, after which data was calculated based on the Chicago Classification advocated by Pandolfino et al. Moreover, for the MII-pH testing, Sleuth manufactured by Sandhill Scientific. Inc. was used and automatic analysis was conducted by a computer. Postoperative assessments were conducted 3 months following surgery for all. Data was described in the median value and inter-quartile range, with a statistically significant difference defined as p < 0.05 by Chi square, Mann-Whitney, and Wilcoxon tests. RESULTS: RE+ group (Los Angeles classification A:B:C:D = 7:9:16:12 patients) included 44 patients (44%), of older age compared to the RE- group (62 vs. 50 years, p = 0.012) and a higher Body Mass Index value (24.0 vs. 22.5, p = 0.045); however, no differences were observed in terms of gender and duration of symptoms. In the preoperative findings on MII-pH, the RE+ group demonstrated significantly longer acid reflux time (4.7 vs. 1.3%, p = 0.005), while in the HRM findings, the RE- group demonstrated a significantly longer abdominal esophagus (0 vs. 0.4 cm, p = 0.049) and maintained esophageal body motor function (DCI: 1054 vs. 1407 mmHg s cm, p = 0.021, Intact peristalsis ratio: 90 vs. 100%, p = 0.037). As to the comparison of the treatment effect before and after laparoscopic fundoplication (Toupet fundoplication for all), significant improvements were observed in both groups in various parameters regarding reflux including acid reflux time, total number of liquid reflux episodes and total number of reflux episodes. Moreover, for both groups, the total length of the lower esophageal sphincter (LES) (RE+ group: 2.7 vs. 3.2 cm, p = 0.001, RE- group: 3.0 vs. 3.4 cm, p = 0.003) and the total length of the abdominal esophagus (RE+ group: 0 vs. 1.6 cm, p < 0.001, RE- group: 0 vs. 1.8 cm, p = 0.001) were significantly extended following surgery; however, no change was observed in DCI before and after surgery. CONCLUSIONS: Regardless of the presence of RE, cardiac function and LES function were improved following laparoscopic Toupet fundoplication, but no changes were observed in esophageal body motor 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.

Gastroesophageal reflux disease. Are we acting in the best interest of our patients?

Oesophageal adenocarcinoma is strictly related to gastroesophageal reflux and cylindrical metaplasia of the epithelium of the distal esophagus (Barrett's esophagus) due to chronic inflammation. Worldwide incidence of oesophageal adenocarcinoma is rising despite the availability of precise international guidelines for the treatment of gastroesophageal reflux disease and the increasing use of proton-pump inhibitors (PPIs). While PPIs can control GERD symptoms in a significant amount of cases, still a large number of patients progress to Barrett's esophagus and adenocarcinoma. Recent investigations have demonstrated that in one-third of the patients their reflux symptoms are due to non-acid reflux, obviously not affected by PPIs. Robust evidences are available to demonstrate the role of non-acid reflux in the development of Barrett's esophagus and adenocarcinoma. Therefore, PPIs are not effective in preventing the worst complications of GERD. It is mandatory to develop new and more effective guidelines on the treatment of GERD; that would take into account the fact that GERD should be considered a "surgical" disease, as it is due, at least in its late stages, to an anatomical defect of the lower oesophageal sphincter. Medical treatment should be considered in early stage GERD, when reflux is due to transient relaxations of the lower oesophageal sphincter, whereas surgery should be considered in late stages, in the presence of a demonstrated mechanical failure of the sphincter.

Effect of changes in intra-abdominal pressure on diameter, cross-sectional area, and distensibility of the lower esophageal sphincter of healthy dogs as determined by use of an endoscopic functional luminal imaging probe.

OBJECTIVE To evaluate the effect of intra-abdominal pressure (IAP) on morphology and compliance of the lower esophageal sphincter (LES) by use of impedance planimetry in healthy dogs and to quantify the effect of changes in IAP. ANIMALS 7 healthy, purpose-bred sexually intact male hound-cross dogs. PROCEDURES Dogs were anesthetized, and cross-sectional area (CSA), minimal diameter (MD), LES length, LES volume, and distensibility index (DI) of the LES were evaluated by use of an endoscopic functional luminal imaging probe. For each dog, measurements were obtained before (baseline) and after creation of a pneumoperitoneum at an IAP of 4, 8, and 15 mm Hg. Order of the IAPs was determined by use of a randomization software program. RESULTS CSA and MD at 4 and 8 mm Hg were not significantly different from baseline measurements; however, CSA and MD at 15 mm Hg were both significantly greater than baseline measurements. The LES length and LES volume did not differ significantly from baseline measurements at any IAP. The DI differed inconsistently from the baseline measurement but was not substantially affected by IAP. CONCLUSIONS AND CLINICAL RELEVANCE Pneumoperitoneum created with an IAP of 4 or 8 mm Hg did not significantly alter LES morphology in healthy dogs. Pneumoperitoneum at an IAP of 15 mm Hg caused a significant increase in CSA and MD of the LES. Compliance of the LES as measured by the DI was not greatly altered by pneumoperitoneum at an IAP of up to 15 mm Hg.

Length and pressure of the reconstructed lower esophageal sphincter is determined by both crural closure and Nissen fundoplication.

BACKGROUND: Laparoscopic Nissen fundoplication is comprised of: a wrap thought responsible for the lower esophageal sphincter function and crural closure performed to prevent herniation. We hypothesized gastroesophageal junction competence effected by Nissen fundoplication results from closure of the crural diaphragm and creation of the fundoplication. METHODS: Patients with uncomplicated reflux undergoing Nissen fundoplication were prospectively enrolled. After hiatal dissection, patients were randomized to crural closure followed by fundoplication (group 1) or fundoplication followed by crural closure (group 2). Intra-operative high-resolution manometry collected sphincter pressure and length data after complete dissection and after each component repair. RESULTS: Eighteen patients were randomized. When compared to the completely dissected hiatus, the mean sphincter length increased 1.3 cm (p < 0.001), and mean sphincter pressure was increased by 13.7 mmHg (p < 0.001). Groups 1 and 2 had similar sphincter length and pressure changes. Crural closure and fundal wrap contribute equally to sphincter length, although crural closure appears to contribute more to sphincter pressure. CONCLUSION: The Nissen fundoplication restores the function of the gastroesophageal junction and thus the reflux barrier by means of two main components: the crural closure and the construction of a 360° fundal wrap. Each of these components is equally important in establishing both increased sphincter length and pressure.

Histomorphology and immunohistochemistry of the lower esophageal sphincter of the least shrew (Cryptotis parva).

The biochemical and histopathological changes in the lower esophageal sphincter (LES) in the pathogenesis of gastroesophageal reflux disease have gained interest. The least shrew is able to vomit in response to emetogens and provides a good model to study the histology of this phenomenon relative to the published reports in the commonly used but vomit-incompetent laboratory species. The LES is located at the junction of the esophagus and stomach. It typically closes at rest and opens in response to swallowing. Our findings demonstrate that the least shrew does not have a well-defined LES, lacks esophageal glands and has a mucosal valve-like projection from the terminal end of the esophagus before joining the gastric epithelium at the lesser curvature. In addition, the least shrew has thoracic and abdominal components prior to joining the gastric epithelium. The mucosal lining of the esophagus is folded, becoming clearly convoluted and forming a bucket-like structure at the level of the esophageocardiac junction (ECJ). No significant differences are to be found between the structure and thickness of the wall before and after the ECJ. Thus, the ECJ forming the LES is relatively less complex than those of other mammals including man. The distribution of enterochromaffin (EC) cells is confined to the lamina propria of the junction and is not associated with the cardiac glands, suggesting its functional involvement with the smooth muscle in and around the ECJ. In conclusion, the least shrew's anatomical sphincter appears ill-defined and is replaced by a less sturdy valve-like mucosal flap.

[Clinical anatomy of the esophagogastric junction]. / Anatomia clinica a jonctiunii eso-gastrice.

UNLABELLED: The esophagogastric junction is a controversial anatomical area, due to its sphincteric mechanism which does not show an obvious anatomical basis. The aim of this study is to investigate the anatomical components that endoscopically indicate the mucosal esophagogastric junction in hiatal hernia patients. MATERIAL AND METHODS: The esophagogastric junction was investigated in 27 hiatal hernia patients undergoing surgery. Hiatal hernia is an extension of the stomach situated between the esophagogastric junction and the diaphragmatic indentation. The following types of hiatal hernia were found: sliding hiatal hernia (type I) in 4 patients (14.81%), rolling hiatal hernia (type II) in 2 (7.4%), mixed hiatal hernia (type III) in 12 (44.44%), type IV hiatal hernia in 4 (14.81%) and recurrent hiatal hernia in 5 (18.51%). Of the 27 hiatal hernia patients, 8 (29.6%) were operated using classical procedures: laparotomy--6 (75%) and laparoscopic surgery--2 (25%). RESULTS: The angle of His cannot be used for marking the mucosal esophagogastric junction due to the severe damage of the lower esophageal sphincter in hiatal hernia patients. The squamocolumnar junction is displaced in hiatal hernia patients and was not an option for the study group. The distal end of the esophageal longitudinal palisading vessels needs medication (proton pump inhibitors that reduce the gastric acid production), in order to enhance the visibility of these vessels. The proximal end of gastric longitudinal mucosal folds proved to be the most reliable site to identify endoscopically the mucosal esophagogastric junction. CONCLUSIONS: The anatomical structure of the esophagogastric junction differs in hiatal hernia patients and these peculiarities are very important in surgery.

Role of the lower esophageal sphincter on esophageal acid exposure - a review of over 2000 patients.

BACKGROUND AND AIM: Three lower esophageal sphincter (LES) characteristics associated with gastro-esophageal reflux disease (GERD) are, LES pressure = 6 mmHg, abdominal length (AL) <1 cm and overall length (OL) <2 cm. The objective of this study was to validate this relationship and evaluate the extent of impact various LES characteristics have on the degree of distal esophageal acid exposure. METHODS: A retrospective review of a prospectively maintained database identified patients who underwent esophageal manometry and pH studies at Creighton University Medical Center between 1984 and 2008. Patients with esophageal body dysmotility, prior foregut surgery, missing data, no documented symptoms or no pH study, were excluded. Study subjects were categorized as follows: (1) normal LES (N-LES): patients with LES pressure of 6-26 mmHg, AL = 1.0 cm and OL = 2 cm; (2) incompetent LES (Inc-LES): patients with LES pressure <6.0 mmHg orAL <1 cm or OL <2 cm; and (3) hypertensive LES (HTN-LES): patients with LES pressure >26.0 mmHg with AL = 1 cm and OL = 2 cm. The DeMeester score was used to compare differences in acid exposure between different groups. RESULTS: Two thousand and twenty patients satisfied study criteria. Distal esophageal acid exposure as reflected by the DeMeester score in patients with Inc-LES (median=20.05) was significantly higher than in patients with an N-LES (median=9.5), which in turn was significantly higher than in patients with an HTN-LES. Increasing LES pressure and AL provided protection against acid exposure in a graded fashion. Increasing number of inadequate LES characteristics were associated with an increase both in the percentage of patients with abnormal DeMeester score and the degree of acid exposure. CONCLUSION: LES pressure (=6 mmHg) and AL (<1 cm) are associated with increased lower esophageal acid exposure, and need to be addressed for definitive management of GERD.

Towards minimally invasive monitoring for gastroenterology - An external Squamocolumnar Junction Locator.

Transient lower oesophageal sphincter relaxations (TLOSRs) occur frequently and are the main mechanism of acid reflux. The only means of currently detecting TLOSRs is intra-luminal manometry and the probes themselves may stimulate TLOSRs. The squamo-columnar junction moves 4-5 centimeters proximally during TLOSRs and this provides a means of detecting such episodes. The objective of this work is to develop a sensor system capable of detecting the movement of a miniature magnet attached to the squamo-columnar junction from outside the body and thus allow detection of TLOSRs without the artifact associated with intraluminal detection probes. A GaAs Hall effect sensor was selected and an alternating current supply was developed with a combination of filters and a Phase Sensitive Detector, to detect the magnet. The oscillation frequency of the current was chosen in order to reduce electronic noise, and filtering outside this frequency means the signal to noise ratio was greatly improved. The phase sensitive detector was employed to accurately convert the amplitude of the sensor's output to a DC signal. With the addition of paired Flux Concentrators increases the range up to 10.2 centimetres, an improvement of 580% over commercial Hall effect sensors. The AC circuit and flux concentrator device far exceeds the sensitivity of the current Hall effect sensors supplied in the market, by rejecting noise and providing accurate measurement over significantly larger distances. The development of this sensor has applications beyond this specific medical device.

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.

The lower esophageal sphincter.

The lower esophageal sphincters (LES) together with the crural diaphragm are the major antireflux barriers protecting the esophagus from reflux of gastric content. However, reflux of gastric contents into the esophagus is a normal phenomenon in healthy individuals occurring primarily during episodes of transient lower esophageal sphincter relaxation (TLESR), defined as LES relaxation in the absence of a swallow. Transient lower esophageal sphincter relaxation is also the dominant mechanism of pathologic reflux in gastroesophageal reflux disorder (GERD) patients. Frequency of TLESR does not differ significantly between healthy individuals and those with GERD, but TLESRs are more likely to be associated with acid reflux in GERD patients. Understanding the mechanisms responsible for elicitation of a TLESR, using recently introduced novel technology is an area of intense interest. Pharmacologic and non-pharmacologic manipulation of receptors involved in the control of TLESR has recently emerged as a potential target for GERD therapy.

General anatomy of the esophagus.

This article reviews the embryology and general anatomy of the esophagus, including the topography and relationships of the esophagus to surrounding structures. The esophagus is the only internal organ that traverses 3 body cavities, and a complete understanding of the anatomy and anatomic relationships of the esophagus in each area is essential for surgeons who address esophageal disorders. Details regarding the normal histology and basic function of the esophagus are also provided.

High-resolution esophageal pressure topography is superior to conventional sleeve manometry for the detection of transient lower esophageal sphincter relaxations associated with a reflux event.

BACKGROUND: Transient lower esophageal sphincter relaxations (TLESRs) are the main mechanism underlying gastro-esophageal reflux and are detected during manometric studies using well defined criteria. Recently, high-resolution esophageal pressure topography (HREPT) has been introduced and is now considered as the new standard to study esophageal and lower esophageal sphincter (LES) function. In this study we performed a head-to-head comparison between HREPT and conventional sleeve manometry for the detection of TLESRs. METHODS: A setup with two synchronized MMS-solar systems was used. A solid state HREPT catheter, a water-perfused sleeve catheter, and a multi intraluminal impedance pH (MII-pH) catheter were introduced in 10 healthy volunteers (M6F4, age 19-56). Subjects were studied 0.5 h before and 3 h after ingestion of a standardized meal. Tracings were blinded and analyzed by the three authors according to the TLESR criteria. KEY RESULTS: In the HREPT mode 156 TLESRs were scored, vs 143 during sleeve manometry (P = 0.10). Hundred and twenty-three TLESRs were scored by both techniques. Of all TLESRs (177), 138 were associated with reflux (78%). High-resolution esophageal pressure topography detected significantly more TLESRs associated with a reflux event (132 vs 119, P = 0.015) resulting in a sensitivity for detection of TLESRs with reflux of 96% compared to 86% respectively. Analysis of the discordant TLESRs associated with reflux showed that TLESRs were missed by sleeve manometry due to low basal LES pressure (N = 5), unstable pharyngeal signal (N = 4), and residual sleeve pressure >2 mmHg (N = 10). CONCLUSIONS & INFERENCES: The HREPT is superior to sleeve manometry for the detection of TLESRs associated with reflux. However, rigid HREPT criteria are awaited.

Determination of pH turning point with pH mapping of the gastroesophageal junction: an alternative technique to orientate esophageal pH monitoring.

Manometric location of the lower esophageal sphincter (LES) has been mandatory before esophageal pH monitoring, despite costs and discomfort related with esophageal manometry. The aims of the study were: (i) to map the pH of the gastroesophageal junction (GEJ) to determine a pH turning point (PTP) and its relation with LES; and (ii) to test the feasibility of this technique to orientate esophageal pH monitoring. We studied 310 adult patients who underwent esophageal manometry and pH monitoring off acid-suppressive therapy. GEJ pH mapping was carried out by step-pulling the pH sensor from 5 cm below to 5 cm above LES, and a PTP was determined when pH changed from below to above 4, in centimeters from the nostril. Thirty-six patients referred only for pH monitoring were studied with pH sensor placed at 5 cm above the PTP. Out of 310 patients, a PTP was found in 293 (94.5%): inside LES in 86.3%, into the stomach in 8.2% and in the esophageal body in 5.5% of patients. The median distance between PTP and place where pH sensor monitored reflux was 8 cm. Among 36 patients who performed pH monitoring without LES manometry, there was no gastric monitoring during reflux testing. In adult patients investigated off acid suppressive therapy, GEJ pH mapping with reflux monitoring 5 cm above the PTP can be an alternative technique to perform esophageal pH monitoring when LES manometry is not available. Additional studies are needed before the widespread use of GEJ pH mapping in the clinical practice.

The impact of gastric distension on the lower esophageal sphincter and its exposure to acid gastric juice.

BACKGROUND AND AIMS: The lower esophageal sphincter (LES) in patients with gastroesophageal reflux disease often has a low resting pressure and a short abdominal length. The mechanism by which this occurs is unknown. We hypothesize that gastric distension causes progressive effacement of the abdominal portion of the LES, exposing it to acid injury resulting in mucosal and sphincter damage. Our aim was to assess in normal subjects the effect of gastric distension on the LES length and pressure and its exposure to acid gastric juice. METHODS: Eleven asymptomatic volunteers had their LES length and pressure measured before and during gastric distension. The location of the pH step-up point (shift from gastric pH to a pH >4) was also measured before and after distension. RESULTS: Progressive gastric distension with air resulted in progressive shortening of LES (R = 0.89, P < 0.0001). After infusion of 750 cc of air there was a significant reduction in the median LES length from 4 to 2.6 cm (P = 0.001). This change occurred in the abdominal length of the LES (2.6-1.4 cm [P = 0.001]) and not in the thoracic length. At rest the pH step-up point was 0.5 cm above the lower border of the LES and with distension moved a median of 1 cm cephalad within the LES. Simultaneously with the loss of length there was a reduction in LES pressure (27.4-23.4 mm Hg, P = 0.02). CONCLUSIONS: Gastric distension causes progressive shortening of the abdominal length of the LES and a reduction in its pressure. The process exposes the effaced mucosa and sphincter to acid gastric juice.

The esophageal hiatus: what is the normal size?

BACKGROUND: A hiatal hernia is defined as the protrusion of intra-abdominal organs through a dilated esophageal hiatus. The esophageal hiatus and its function have been described extensively, but an exact anatomical determination of its normal size is lacking. It seems important to define the normal size, as crural closure is an important part of surgical treatment of gastroesophageal reflux disease (GERD) and hiatal or paraesophageal hernias. The aim of this study was to determine normal values for the size of the esophageal hiatus. METHODS: In a prospective study 50 consecutive cadaver autopsies were performed between February and May 2008. The subjects had died from several diseases not related to GERD. Size of the esophageal hiatus was measured after opening the abdominal cavity before extirpation of any organs. Distance of the cardia and gastroesophageal junction and position of the angle of His were further measured. A formula was used to calculate the hiatal surface area (HSA). Results were analyzed regarding subject height, weight, body mass index (BMI), and chest circumference. RESULTS: In all 50 cadavers (24 male/26 female) the autopsy was performed and all measurements were obtained. Mean age was 74 years (40-90 years), mean height was 1.68 m (1.39-1.83 m), mean weight was 71 kg (40-120 kg), and mean body mass index (BMI) was 25 kg/m(2) (14-40 kg/m(2)). Mean chest circumference was 101 cm (75-178 range). Mean HSA was 5.84 cm(2) (3.62-9.56 cm(2)). In all cadavers the gastroesophageal junction was intraabdominal, the mean distance to the angle of His was 3.6 cm (2.7-4.6 cm), the mean length of the right and left crura was similar at 3.6 cm (2.7-4.6 cm), and the opening segment had a mean length of 2.4 cm (1.7-4.0 cm). CONCLUSION: The mean HSA was determined in these normal subjects to be 5.84 cm(2). It was directly proportional to chest circumference and independent of height, weight, BMI, and gender.

Asymmetrical circumferential distribution of esophagogastric junctional lesions: anatomical and physiological considerations.

Several components of the gastrointestinal tract including the esophagogastric junction (EGJ) show circumferential asymmetry in the formation of pathological lesions, which is caused by the morphological and functional asymmetry of the gastrointestinal tract. Pressure in the lower esophageal sphincter (LES) is higher on the left posterior side as compared to the right anterior side, which may partly explain why Mallory-Weiss tears frequently occur on the right side wall of the EGJ. Lower LES pressure in the right anterior wall may not effectively prevent gastroesophageal reflux on this side and may be a reason why esophageal erosions in patients with reflux esophagitis, short segment Barrett's esophagus, and adenocarcinomas associated with short segment Barrett's esophagus are frequently found in the right anterior wall of the esophagus. In addition, acidic gastroesophageal reflux may also cause rupture of esophageal varices predominantly on that side. Thus, asymmetrical LES pressure may be a cause of the right anterior side predominance of diseases found in this part of the gastrointestinal tract.