Anatomy and physiology of the esophageal body

Regurgitation, eructation, and supragastric belch: retrograde esophageal motility, disorders, and treatment

PURPOSE OF REVIEW

This review describes pathologic conditions of retrograde flow into the esophagus along with recent therapeutic advances and treatment options.

RECENT FINDINGS

The esophagus facilitates anterograde and retrograde movement of contents, the latter of which is mediated by transient lower esophageal sphincter relaxations (TLESRs). Gastroesophageal reflux disease (GERD) often includes esophageal-specific symptoms such as heartburn or regurgitation. Volume regurgitation responds less frequently to acid suppression with proton pump inhibitors (PPIs) than heartburn, given its relationship with incompetence of the esophagogastric junction (EGJ) and increased frequency of TLESRs. Therefore, although the refluxate pH can be altered with PPIs, the frequency of reflux episodes is generally not reduced and surgical and endoscopic treatments may be favored. Other instances of abnormal retrograde esophageal flow respond better to medical therapy, or lifestyle interventions. Compared to gastric belching because of increased stomach distension, supragastric belching is caused by intake of air from pharynx into the esophagus followed by rapid expulsion of air. These conditions can be distinguished on esophageal tests such as high-resolution manometry and are likely to respond to behavioral modifications.

SUMMARY

Retrograde flow into the esophagus can be a normal occurrence, but diagnostic testing to distinguish causes can guide appropriate intervention.

Anatomic and Manometric Abnormalities of the Upper and Lower Esophageal Sphincters in Patients With Reflux Disease

RESEARCH QUESTION

Laryngopharyngeal reflux (LPR) may cause inflammation of the laryngeal and pharyngeal mucosa. Gastroesophageal reflux disease (GERD) involves retrograde flow of gastric content into the esophagus below the upper esophageal sphincter (UES). The goal of this study was to investigate the esophageal anatomical and manometric variations of the esophagus in patients with LPR and/or GERD.

METHODS

Adult voice center patients who underwent diagnostic workup for reflux complaints with 24-hour multichannel intraluminal pH-impedance testing and esophageal manometry were included in this retrospective study. Subjects were classified as having LPR (>10 proximal reflux events), LPR + GERD (>10 proximal reflux events plus >73 distal reflux events) or were assigned to a control group (≤10 proximal events and ≤73 distal reflux events) based on pH study results. Anatomic and manometric parameters were evaluated between groups.

RESULTS

There were 169 cases (65 male, 104 female) included in this study. The average age was 50.50 ± 17.29. Subjects in the LPR group had significantly higher UES relaxation pressures and greater UES length compared with the control group. Lower esophageal sphincter relaxation pressure was significantly higher in the control group compared with the LPR group or the GERD + LPR group. Subjects in the GERD + LPR group had a significantly shorter intra-abdominal portion of the lower esophageal sphincter compared with the LPR only group and the control group. Intrabolus pressure was significantly lower in both the LPR group and the LPR + GERD group compared with the control group. Distal wave amplitude was significantly lower in the LPR + GERD group compared to both the LPR group and the control group. The percentage of swallows with incomplete clearance was significantly greater in the LPR + GERD group than both the control group and the LPR group. The LPR group had significantly fewer swallows with incomplete clearance than the control group.

CONCLUSIONS

Anatomic and manometric abnormalities are present in subjects with LPR with or without GERD and may contribute to the pathogenesis of reflux disease. Further research is needed to confirm or refute these findings.

Physiological Mechanisms and Associated Pathophysiology of Dysphagia in Older Adults

Dysphagia can be a common secondary sequela of neurological and neurodegenerative disorders in older adults. Early screening, identification, and management of dysphagia is essential to avoid serious complications, including malnutrition, dehydration, aspiration pneumonia; and promote quality of life. Although individuals of all ages may experience swallowing difficulties, dysphagia and its complications are more common in older adults. This literature review aims to provide an overview of the physiological mechanisms of normal swallowing in healthy individuals and age-related changes to swallowing function, the pathophysiology of dysphagia associated with three common neurological disorders affecting older adults (stroke, Parkinson's disease, and dementia), and implications for interdisciplinary clinical practice. Increased awareness of these issues may contribute to a more timely and efficient identification of older adults with dysphagia and to improve overall dysphagia management.

Understanding the most commonly billed diagnoses in primary care: Gastroesophageal reflux disease

ABSTRACT

Gastroesophageal reflux disease (GERD) is a chronic, relapsing condition encountered commonly in primary care with an estimated worldwide prevalence of up to 33%. GERD affects all age groups, races, and genders with 25% of the population in the Western world experiencing heartburn at least once a month.

Activin A affects feeding by promoting the inner diameter and muscle development of the pharynx and oesophagus in zebrafish (Danio rerio) larvae

Activin A belongs to the superfamily of transforming growth factor-β and plays an important role in hormone regulation and tissue development. However, few research studies have been conducted on the effect of activin A on feeding organs in fish. In this study, the zebrafish (Danio rerio) larvae were treated with 1 ng ml^-1 activin A for 8 days continuously. The haematoxylin and eosin (H&E) staining section results revealed that the transverse inner diameter of the pharynx and oesophagus significantly increased on the third and eighth days after treatment compared with the control group (P < 0.05). On the eighth day, the cross-sectional area of the pharyngeal muscle increased by 8638 μm² compared to the control group (P < 0.05). The RNA in situ hybridization results also showed that the expression of skeletal muscle-specific genes (myog and myod) was significantly increased in pharyngeal muscle on the eighth day. Furthermore, the qRT-PCR results showed the expression of gh gene was significantly increased on the eighth day (P < 0.05). At the same time, more larvae in activin A group were able to feed larger brine shrimp (Artemia) than in the control group on the eighth day. In conclusion, activin A could affect feeding by promoting the inner diameter and muscle development of the pharynx and oesophagus in zebrafish larvae. This study is the first to report that the development of the pharynx and oesophagus can directly affect food intake in fish larvae, which provides a theoretical basis for the study of food intake of fish at an early stage.

Endoscope presence during endoluminal functional lumen imaging probe (FLIP) influences FLIP metrics in the evaluation of esophageal dysmotility

BACKGROUND

The functional lumen imaging probe (FLIP) system is an FDA-approved tool for dynamic evaluation of the esophagogastric junction (EGJ). Even though commercially available since 2009, FLIP utilization remains low, partly due to lack of consensus in methodology and interpretation. Therefore, we aimed to analyze the influence of concurrent endoscopy on FLIP measurements.

METHODS

In this single-center study, we reviewed data from 93 patients undergoing FLIP for symptomatic esophageal motility disorders between 2016 and 2018. During sedated endoscopy, we measured luminal values (distensibility, cross-sectional area (CSA), and balloon pressure) at the EGJ and distal esophagus using 30, 40, and 50 mL distension volumes, with and without concurrent endoscope presence. All recorded values were compared at the various distension volumes between the two measurements using a Wilcoxon rank sum test.

KEY RESULTS

There was a significant difference in distensibility and CSA with index distension volume (40 mL) at the EGJ comparing the two measurements: Lower median distensibility was 2.1 mm²  mm Hg^-1 in the group with concurrent inserted endoscope, respectively, 3.4 mm²  mm Hg^-1 without endoscope (P < .001), and median CSA was 86.0 resp. 110.0 mm² (P < .001). No significant difference could be found in the measurements of the distal esophagus.

CONCLUSIONS & INFERENCES

Our results show a significant difference in FLIP measurements with and without endoscope presence. This underlines the importance of establishing a consensus of a standardized FLIP protocol to define normal luminal values and guiding future FLIP diagnostic studies.

Impairment of Nitric Oxide Pathway by Intravascular Hemolysis Plays a Major Role in Mice Esophageal Hypercontractility: Reversion by Soluble Guanylyl Cyclase Stimulator

Paroxysmal nocturnal hemoglobinuria (PNH) patients display exaggerated intravascular hemolysis and esophageal disorders. Since excess hemoglobin in the plasma causes reduced nitric oxide (NO) bioavailability and oxidative stress, we hypothesized that esophageal contraction may be impaired by intravascular hemolysis. This study aimed to analyze the alterations of the esophagus contractile mechanisms in a murine model of exaggerated intravascular hemolysis induced by phenylhydrazine (PHZ). For comparative purposes, sickle cell disease (SCD) mice were also studied, a less severe intravascular hemolysis model. Esophagus rings were dissected free and placed in organ baths. Plasma hemoglobin was higher in PHZ compared with SCD mice, as expected. The contractile responses produced by carbachol (CCh), KCl, and electrical-field stimulation (EFS) were superior in PHZ esophagi compared with control but remained unchanged in SCD mice. Preincubation with the NO-independent soluble guanylate cyclase stimulator 3-(4-amino-5-cyclopropylpyrimidin-2-yl)-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine (BAY 41-2272; 1 μM) completely reversed the increased contractile responses to CCh, KCl, and EFS in PHZ mice, but responses remained unchanged with prior treatment with NO donor sodium nitroprusside (300 μM). Protein expression of 3-nitrotyrosine and 4-hydroxynonenal increased in esophagi from PHZ mice, suggesting a state of oxidative stress. In endothelial nitric oxide synthase gene-deficient mice, the contractile responses elicited by KCl and CCh were increased in the esophagus but remained unchanged with the intravascular hemolysis induced by PHZ. In conclusion, our results show that esophagus hypercontractile state occurs in association with lower NO bioavailability due to exaggerated hemolysis intravascular and oxidative stress. Moreover, our study supports the hypothesis that esophageal disorders in PNH patients are secondary to intravascular hemolysis affecting the NO-cGMP pathway.

Development and stem cells of the esophagus

The esophagus is derived from the anterior portion of the developmental intermediate foregut, a structure that also gives rise to other organs including the trachea, lung, and stomach. Genetic studies have shown that multiple signaling pathways (e.g. Bmp) and transcription factors (e.g. SOX2) are required for the separation of the esophagus from the neighboring respiratory system. Notably, some of these signaling pathways and transcription factors continue to play essential roles in the subsequent morphogenesis of the esophageal epithelium which undergoes a simple columnar-to-stratified squamous conversion. Reactivation of the relevant signaling pathways has also been associated with pathogenesis of esophageal diseases that affect the epithelium and its stem cells in adults. In this review we will summarize these findings. We will also discuss new data regarding the cell-of-origin for the striated and smooth muscles surrounding the esophagus and how they are differentiated from the mesenchyme during development.

Practice guidelines on the use of esophageal manometry - A GISMAD-SIGE-AIGO medical position statement

Patients with esophageal symptoms potentially associated to esophageal motor disorders such as dysphagia, chest pain, heartburn and regurgitation, represent one of the most frequent reasons for referral to gastroenterological evaluation. The utility of esophageal manometry in clinical practice is: (1) to accurately define esophageal motor function, (2) to identify abnormal motor function, and (3) to establish a treatment plan based on motor abnormalities. With this in mind, in the last decade, investigations and technical advances, with the introduction of high-resolution esophageal manometry, have enhanced our understanding and management of esophageal motility disorders. The following recommendations were developed to assist physicians in the appropriate use of esophageal manometry in modern patient care. They were discussed and approved after a comprehensive review of the medical literature pertaining to manometric techniques and their recent application. This position statement created under the auspices of the Gruppo Italiano di Studio per la Motilità dell'Apparato Digerente (GISMAD), Società Italiana di Gastroenterologia ed Endoscopia Digestiva (SIGE) and Associazione Italiana Gastroenterologi ed Endoscopisti Digestivi Ospedalieri (AIGO) is intended to help clinicians in applying manometric studies in the most fruitful manner within the context of their patients with esophageal symptoms.

A Cranial Mesoderm Origin for Esophagus Striated Muscles

The esophagus links the oral cavity to the stomach and facilitates the transfer of bolus. Using genetic tracing and mouse mutants, we demonstrate that esophagus striated muscles (ESMs) are not derived from somites but are of cranial origin. Tbx1 and Isl1 act as key regulators of ESMs, which we now identify as a third derivative of cardiopharyngeal mesoderm that contributes to second heart field derivatives and head muscles. Isl1-derived ESM progenitors colonize the mouse esophagus in an anterior-posterior direction but are absent in the developing chick esophagus, thus providing evolutionary insight into the lack of ESMs in avians. Strikingly, different from other myogenic regions, in which embryonic myogenesis establishes a scaffold for fetal fiber formation, ESMs are established directly by fetal myofibers. We propose that ESM progenitors use smooth muscle as a scaffold, thereby bypassing the embryonic program. These findings have important implications in understanding esophageal dysfunctions, including dysphagia, and congenital disorders, such as DiGeorge syndrome.