A wave of inhibition precedes primary peristaltic contractions in the human esophagus

Enhancing Chicago Classification diagnoses with functional lumen imaging probe-mechanics (FLIP-MECH)

BACKGROUND

Esophageal motility disorders can be diagnosed by either high-resolution manometry (HRM) or the functional lumen imaging probe (FLIP) but there is no systematic approach to synergize the measurements of these modalities or to improve the diagnostic metrics that have been developed to analyze them. This work aimed to devise a formal approach to bridge the gap between diagnoses inferred from HRM and FLIP measurements using deep learning and mechanics.

METHODS

The "mechanical health" of the esophagus was analyzed in 740 subjects including a spectrum of motility disorder patients and normal subjects. The mechanical health was quantified through a set of parameters including wall stiffness, active relaxation, and contraction pattern. These parameters were used by a variational autoencoder to generate a parameter space called virtual disease landscape (VDL). Finally, probabilities were assigned to each point (subject) on the VDL through linear discriminant analysis (LDA), which in turn was used to compare with FLIP and HRM diagnoses.

RESULTS

Subjects clustered into different regions of the VDL with their location relative to each other (and normal) defined by the type and severity of dysfunction. The two major categories that separated best on the VDL were subjects with normal esophagogastric junction (EGJ) opening and those with EGJ obstruction. Both HRM and FLIP diagnoses correlated well within these two groups.

CONCLUSION

Mechanics-based parameters effectively estimated esophageal health using FLIP measurements to position subjects in a 3-D VDL that segregated subjects in good alignment with motility diagnoses gleaned from HRM and FLIP studies.

Systematic Review With Meta-Analysis: Chronic Opioid Use Is Associated With Esophageal Dysmotility in Symptomatic Patients

INTRODUCTION

We aimed to conduct a systematic review and meta-analysis to assess the impact of chronic opioid exposure on esophageal motility in patients undergoing manometric evaluation.

METHODS

Multiple databases were searched through October 2022 for original studies comparing the manometric results of patients who have used chronic opioids (for >90 days) with those who do not. The primary outcomes were esophageal dysmotility disorders. Three high-resolution manometry parameters were conducted as secondary outcomes. A random-effects model was applied to calculate the odds ratio (OR) and means difference (MD) along with a 95% confidence interval (CI).

RESULTS

Nine studies were included in this meta-analysis. Opioid use was associated with higher esophageal dysmotility disorders, including distal esophageal spasm (pooled OR 4.84, 95% CI 1.60-14.63, P = 0.005, I 2 = 96%), esophagogastric junction outflow obstruction (pooled OR 5.13, 95% CI 2.11-12.43, P = 0.0003, I 2 = 93%), and type III achalasia (pooled OR 4.15, 95% CI 2.15-8.03, P < 0.0001, I 2 = 64%). No significant differences were observed for hypercontractile esophagus, type I achalasia, or type II achalasia. The basal lower esophageal sphincter pressure (MD 3.02, 95% CI 1.55-4.50, P < 0.0001, I 2 = 90%), integrated relaxation pressure (MD 2.51, 95% CI 1.56-3.46, P < 0.00001, I 2 = 99%), and distal contractile integral (MD 640.29, 95% CI 469.56-811.03, P < 0.00001, I 2 = 91%) significantly differed between the opioid use and nonopioid use group. However, opioid use was associated with a lower risk of ineffective esophageal motility (pooled OR 0.68, 95% CI 0.49-0.95, P = 0.02, I 2 = 53%).

DISCUSSION

Chronic opioid exposure is associated with an increased frequency esophageal dysmotility disorders. Our results revealed that opioid use is significantly associated with type III achalasia but not with type I and II achalasia. Therefore, opioid treatment should be taken into account as a potential underlying risk factor when diagnosing these major esophageal motor abnormalities.

Why so Many Patients With Dysphagia Have Normal Esophageal Function Testing

Esophageal peristalsis involves a sequential process of initial inhibition (relaxation) and excitation (contraction), both occurring from the cranial to caudal direction. The bolus induces luminal distension during initial inhibition (receptive relaxation) that facilitates smooth propulsion by contraction travelling behind the bolus. Luminal distension during peristalsis in normal subjects exhibits unique characteristics that are influenced by bolus volume, bolus viscosity, and posture, suggesting a potential interaction between distension and contraction. Examining distension-contraction plots in dysphagia patients with normal bolus clearance, ie, high-amplitude esophageal peristaltic contractions, esophagogastric junction outflow obstruction, and functional dysphagia, reveal 2 important findings. Firstly, patients with type 3 achalasia and nonobstructive dysphagia show luminal occlusion distal to the bolus during peristalsis. Secondly, patients with high-amplitude esophageal peristaltic contractions, esophagogastric junction outflow obstruction, and functional dysphagia exhibit a narrow esophageal lumen through which the bolus travels during peristalsis. These findings indicate a relative dynamic obstruction to bolus flow and reduced distensibility of the esophageal wall in patients with several primary esophageal motility disorders. We speculate that the dysphagia sensation experienced by many patients may result from a normal or supernormal contraction wave pushing the bolus against resistance. Integrating representations of distension and contraction, along with objective assessments of flow timing and distensibility, complements the current classification of esophageal motility disorders that are based on the contraction characteristics only. A deeper understanding of the distensibility of the bolus-containing esophageal segment during peristalsis holds promise for the development of innovative medical and surgical therapies to effectively address dysphagia in a substantial number of patients.

Effect of inter-swallow interval on striated esophagus peristalsis; a comparative study with smooth muscle esophagus

BACKGROUND

Effect of inter-swallow interval on the contractility of smooth muscle esophagus is well-documented. However, the effects on peristalsis of the striated esophagus have not been systematically studied. A better understanding of striated esophagus motor function in health and disease may enhance the interpretation of manometric studies and inform clinical care. The aim of this study was to assess the effect of inter-swallow interval on striated esophagus compared to findings with that of the smooth muscle esophagus.

METHODS

We performed two sets of studies to (1) determine the effect of various inter-swallow interval in 20 healthy volunteers and (2) assess the effect of ultra-short swallow intervals facilitated by straw drinking in 28 volunteers. We analyzed variables using ANOVA with Tukey's pairwise comparison and paired t-test.

KEY RESULTS

Unlike smooth muscle esophagus, the striated esophagus contractile integral did not change significantly for swallow intervals ranging from 30 to 5 s. On the contrary, striated esophagus demonstrated absent or reduced peristalsis in response to ultra-short (<2 s) intervals during straw-facilitated multiple rapid swallows.

CONCLUSIONS AND INFERENCES

Striated esophagus peristalsis is subject to manometrically observed inhibition during swallows with ultra-short intervals. Inter-swallow intervals as short as 5 s that inhibit smooth muscle esophagus peristalsis do not inhibit striated muscle peristalsis. The mechanisms of these observations are unknown but may relate to central or myenteric nervous system influences or the effects of pharyngeal biomechanics.

Distension contraction plots of pharyngeal/esophageal peristalsis: next frontier in the assessment of esophageal motor function

Esophageal peristalsis consists of initial inhibition (relaxation) followed by excitation (contraction), both of which move sequentially in the aboral direction. Initial inhibition results in receptive relaxation and bolus-induced luminal distension, which allows propulsion by the contraction with minimal resistance to flow. Similar to the contraction wave, luminal distension has unique waveform characteristics in normal subjects; both are modulated by bolus volume, bolus viscosity, and posture, suggesting a possible cause-and-effect relationship between the two. Distension contraction plots in patients with dysphagia with normal bolus clearance [high-amplitude esophageal contractions (HAECs), esophagogastric junction outflow obstruction (EGJOO), and functional dysphagia (FD)] reveal two major findings: 1) unlike normal subjects, there is luminal occlusion distal to bolus during peristalsis in certain patients, i.e., with type 3 achalasia and nonobstructive dysphagia; and 2) bolus travels through a narrow lumen esophagus during peristalsis in patients with HAECs, EGJOO, and FD. Aforementioned findings indicate a relative dynamic obstruction to the bolus flow during peristalsis and reduced distensibility of esophageal wall in the bolus segment of the esophagus. We speculate that a normal or supernormal contraction wave pushing bolus against resistance is the mechanism of dysphagia sensation in significant number of patients. Representations of distension and contraction, combined with objective measures of flow timing and distensibility are complementary to the current scheme of classifying esophageal motility disorders based solely on the characteristics of contraction phase of peristalsis. Better understanding of the distensibility of the bolus-containing segment of the esophagus during peristalsis will lead to the development of novel medical and surgical therapies in the treatment of dysphagia in significant number of patients.

Rhythmic contraction but arrhythmic distension of esophageal peristaltic reflex in patients with dysphagia

Background

Reason for dysphagia in a significant number of patients remains unclear even after a thorough workup. Each swallow induces esophageal distension followed by contraction of the esophagus, both of which move sequentially along the esophagus. Manometry technique and current system of classifying esophageal motility disorders (Chicago Classification) is based on the analysis of the contraction phase of peristalsis.

Goal

Whether patients with unexplained dysphagia have abnormalities in the distension phase of esophageal peristalsis is not known.

Methods

Using Multiple Intraluminal esophageal impedance recordings, which allow determination of the luminal cross-sectional area during peristalsis, we studied patients with nutcracker esophagus (NC), esophagogastric junction outflow obstruction (EGJOO), and functional dysphagia (FD).

Results

Distension contraction plots revealed that swallowed bolus travels significantly faster through the esophagus in all patient groups as compared to normals. The luminal cross-sectional area (amplitude of distension), and the area under the curve of distension were significantly smaller in patients with NC, EGJOO, and FD as compared to normals. Bolus traverses the esophagus in the shape of an “American Football” in normal subjects. On the other hand, in patients the bolus flow was fragmented. ROC curves revealed that bolus flow abnormalities during peristalsis are a sensitive and specific marker of dysphagia.

Conclusion

Our findings reveal abnormality in the distension phase of peristalsis (a narrow lumen esophagus) in patients with dysphagia. We propose that the esophageal contraction forcing the swallowed bolus through a narrow lumen esophagus is the cause of dysphagia sensation in patients with normal contraction phase of peristalsis.

Distension-contraction profile of peristalsis in patients with nutcracker esophagus

INTRODUCTION

High amplitude peristaltic esophageal contractions, that is, nutcracker esophagus, were originally described in association with "angina-like pain" of esophageal origin. However, significant number of nutcracker patients also suffer from dysphagia. High-resolution esophageal manometry (HRM) assesses only the contraction phase of peristalsis. The degree of esophageal distension during peristalsis is a surrogate of relaxation and can be measured from the intraluminal esophageal impedance measurements.

AIMS

Determine the amplitude of distension and temporal relationship between distension and contraction during swallow-induced peristalsis in nutcracker patients.

METHODS

HRM impedance (HRMZ) studies were performed and analyzed in 24 nutcracker and 30 normal subjects in the Trendelenburg position. A custom-built software calculated the numerical data of the amplitudes of distension and contraction, the area under the curve (AUC) of distension and contraction, and the temporal relationship between distension and contraction.

RESULTS

In normal subjects, the distension peaks similar to contraction traverse sequentially the esophagus. The amplitude of contraction is greater in the nutcracker esophagus but the amplitude of distension and area under the curve of distension are smaller in patients compared to controls. Distension peaks are aligned closely with contraction in normal subjects, but in patients, the bolus travels faster to the distal esophagus, resulting in a smaller time interval between the onset of swallow and distension peak. Receiver operative characteristics (ROC) curve reveals high sensitivity and specificity of the above parameters in patients.

CONCLUSION

Abnormalities in the distension phase of peristalsis are a possible mechanism of dysphagia in patients with nutcracker esophagus.

European Society for Neurogastroenterology and Motility (ESNM) recommendations for the use of high-resolution manometry of the esophagus

BACKGROUND

Several patients in gastroenterology practice present with esophageal symptoms, and in case of normal endoscopy with biopsies, high-resolution manometry (HRM) is often the next step. Our aim was to develop a European consensus on the clinical application of esophageal HRM, to offer the clinician guidance in selecting patients for HRM and using its results to optimize clinical outcome.

METHODS

A Delphi consensus was initiated with 38 multidisciplinary experts from 16 European countries who conducted a literature summary and voting process on 71 statements. Quality of evidence was evaluated using grading of recommendations assessment, development, and evaluation (GRADE) criteria. Consensus (defined as >80% agreement) was reached for 33 statements.

RESULTS

The process generated guidance on when to consider esophageal HRM, how to perform it, and how to generate the report. The Delphi process also identified several areas of uncertainty, such as the choice of catheters, the duration of fasting and the position in which HRM is performed, but recommended to perform at least 10 5-ml swallows in supine position for each study. Postprandial combined HRM impedance is considered useful for diagnosing rumination. There is a large lack of consensus on treatment implications of HRM findings, which is probably the single area requiring future targeted research.

CONCLUSIONS AND INFERENCES

A multinational and multidisciplinary group of European experts summarized the current state of consensus on technical aspects, indications, performance, analysis, diagnosis, and therapeutic implications of esophageal HRM.

Rapid activation of esophageal mechanoreceptors alters the pharyngeal phase of swallow: Evidence for inspiratory activity during swallow

Swallow is a complex behavior that consists of three coordinated phases: oral, pharyngeal, and esophageal. Esophageal distension (EDist) has been shown to elicit pharyngeal swallow, but the physiologic characteristics of EDist-induced pharyngeal swallow have not been specifically described. We examined the effect of rapid EDist on oropharyngeal swallow, with and without an oral water stimulus, in spontaneously breathing, sodium pentobarbital anesthetized cats (n = 5). Electromyograms (EMGs) of activity of 8 muscles were used to evaluate swallow: mylohyoid (MyHy), geniohyoid (GeHy), thyrohyoid (ThHy), thyropharyngeus (ThPh), thyroarytenoid (ThAr), cricopharyngeus (upper esophageal sphincter: UES), parasternal (PS), and costal diaphragm (Dia). Swallow was defined as quiescence of the UES with overlapping upper airway activity, and it was analyzed across three stimulus conditions: 1) oropharyngeal water infusion only, 2) rapid esophageal distension (EDist) only, and 3) combined stimuli. Results show a significant effect of stimulus condition on swallow EMG amplitude of the mylohyoid, geniohyoid, thyroarytenoid, diaphragm, and UES muscles. Collectively, we found that, compared to rapid cervical esophageal distension alone, the stimulus condition of rapid distension combined with water infusion is correlated with increased laryngeal adductor and diaphragm swallow-related EMG activity (schluckatmung), and post-swallow UES recruitment. We hypothesize that these effects of upper esophageal distension activate the brainstem swallow network, and function to protect the airway through initiation and/or modulation of a pharyngeal swallow response.

Chicago Classification of esophageal motility disorders: Past, present, and future

The Chicago Classification (CC) is a dynamic, evolving classification scheme created by a diverse group of international esophageal experts. Its application has transformed the way esophageal motor data are used to define motility disorders, each iteration seeking to advance, simplify, and standardize the way clinicians worldwide diagnose esophageal dysmotility. The most recent update, CC version 4.0 (CCv4.0), emphasizes the importance of clinical context and distinguishes clinically relevant, conclusive manometric diagnoses from irrelevant manometric observations. Future iterations of CC may refine the classification of spastic esophageal disorders and incorporate machine learning and physics-based modeling to improve metrics.

Hypercontractile Esophagus From Pathophysiology to Management: Proceedings of the Pisa Symposium

Hypercontractile esophagus (HE) is a heterogeneous major motility disorder diagnosed when ≥20% hypercontractile peristaltic sequences (distal contractile integral >8,000 mm Hg*s*cm) are present within the context of normal lower esophageal sphincter (LES) relaxation (integrated relaxation pressure < upper limit of normal) on esophageal high-resolution manometry (HRM). HE can manifest with dysphagia and chest pain, with unclear mechanisms of symptom generation. The pathophysiology of HE may entail an excessive cholinergic drive with temporal asynchrony of circular and longitudinal muscle contractions; provocative testing during HRM has also demonstrated abnormal inhibition. Hypercontractility can be limited to the esophageal body or can include the LES; rarely, the process is limited to the LES. Hypercontractility can sometimes be associated with esophagogastric junction (EGJ) outflow obstruction and increased muscle thickness. Provocative tests during HRM can increase detection of HE, reproduce symptoms, and predict delayed esophageal emptying. Regarding therapy, an empiric trial of a proton pump inhibitor, should be first considered, given the overlap with gastroesophageal reflux disease. Calcium channel blockers, nitrates, and phosphodiesterase inhibitors have been used to reduce contraction vigor but with suboptimal symptomatic response. Endoscopic treatment with botulinum toxin injection or pneumatic dilation is associated with variable response. Per-oral endoscopic myotomy may be superior to laparoscopic Heller myotomy in relieving dysphagia, but available data are scant. The presence of EGJ outflow obstruction in HE discriminates a subset of patients who may benefit from endoscopic treatment targeting the EGJ.

Response to multiple rapid swallows shows impaired inhibitory pathways in distal esophageal spasm patients with and without concomitant esophagogastric junction outflow obstruction

Distal esophageal spasm (DES) is a motility disorder characterized by premature contraction of the esophageal body during single swallows. It is thought to be due to impairment of esophageal inhibitory pathways, but studies to support this are limited. The normal response to multiple rapid swallows (MRS) is deglutitive inhibition of the esophageal body during the MRS sequence. Our aim was to compare the response to MRS in DES patients and healthy control subjects. Response to MRS during HRM was evaluated in 19 DES patients (8 with and 11 without concomitant esophagogastric junction outflow obstruction [EGJOO]) and 24 asymptomatic healthy controls. Patients with prior gastroesophageal surgery, peroral endoscopic myotomy, pneumatic dilation, esophageal botulinum toxin injection within 6 months of HRM, opioid medication use, and esophageal stricture were excluded. Response to MRS was evaluated for complete versus impaired inhibition (esophageal body contractility with distal contractile integral [DCI] > 100 mmHg-sec-cm during MRS), presence of post-MRS contraction augmentation (DCI post MRS greater than single swallow mean DCI), and integrated relaxation pressure (IRP). Impaired deglutitive inhibition during MRS was significantly more frequent in DES compared to controls (89% vs. 0%, P < 0.001), and frequency was similar for DES with versus without concomitant EGJOO (100% vs. 82%, P = 0.48). The proportion of subjects with augmentation post MRS was similar for both groups (37% vs. 38%, P = 1.00), but mean DCI post MRS was higher in DES than controls (3360.0 vs. 1238.9, P = 0.009). IRP was lower during MRS compared to single swallows in all patients, and IRP during MRS was normal in 5 of 8 patients with DES and EGJOO. Our study suggests that impaired deglutitive inhibition during MRS is present in the majority of patients with DES regardless of whether they have concomitant EGJOO, and future studies should explore the usefulness of incorporating response to MRS in the diagnosis of DES.

Relationship between distension-contraction waveforms during esophageal peristalsis: effect of bolus volume, viscosity, and posture

High-resolution esophageal manometry (HRM) in its current form assesses only the contraction phase of peristalsis. Degree of esophageal distension ahead of contraction is a surrogate of relaxation and can be measured from intraluminal esophageal impedance measurements. The characteristics of esophageal contractions, i.e., their amplitude, duration, velocity, and modulating factors, have been well studied. We studied the effect of bolus volume and viscosity and posture on swallow-induced distension and contraction and the temporal relationship between the two. HRM impedance recordings of 50 healthy subjects with no esophageal symptoms were analyzed. Eight to ten swallows of 5 and 10 mL of 0.5 N saline and a viscous bolus were recorded in the supine and Trendelenburg positions. Custom-built computer software generated the distension-contraction plots and numerical data of the amplitudes of distension (cross-sectional area) and contraction, and the temporal relationship between distension and peak contraction. The hallmarks of distension waveforms are that 1) distension peak, similarly to contraction, travels the esophagus in a peristaltic fashion, and the amplitude of distension increases from the proximal-to-distal direction; 2) the amplitude of distension is greater with 10 mL than with 5 mL and greater in Trendelenburg than in supine posture; and 3) bolus viscosity increases the amplitude of distension and alters the temporal relationship between distension and contraction waveforms. We describe the characteristics of esophageal distension during peristalsis and the relationship between distension and contraction in a relatively large cohort of normal subjects. These data can be used to compare differences between normal subjects and patients with various esophageal motility disorders in future studies.NEW & NOTEWORTHY We studied esophageal distension (surrogate of inhibition) ahead of contraction during peristalsis from intraluminal esophageal impedance measurements. Esophageal distension, similarly to contraction, travels the esophagus in a sequential manner, and the amplitude of esophageal distension increases from proximal to distal direction in the esophagus. Bolus volume, viscosity and posture have significant effects on the amplitude of distension and its temporal relationship with contraction.

Opioids Interfere With Deglutitive Inhibition Assessed by Response to Multiple Rapid Swallows During High-Resolution Esophageal Manometry

INTRODUCTION

Normal response to multiple rapid swallows (MRS) during high-resolution esophageal manometry is deglutitive inhibition; opioids may interfere with this. The aim of this study was to evaluate the response to MRS in patients on opioids, not on opioids, and healthy controls.

METHODS

Response to MRS was evaluated for complete vs impaired inhibition in 72 chronic opioid users, 100 patients not on opioids, and 24 healthy controls.

RESULTS

Impaired deglutitive inhibition was significantly more frequent in chronic opioid users compared with patients not on opioids and healthy controls (54% vs 14% vs 0%; P < 0.0001).

DISCUSSION

Impaired deglutitive inhibition during MRS is frequent in opioid users, supporting that opioids interfere with esophageal inhibitory signals.

Neuronal Control of Esophageal Peristalsis and Its Role in Esophageal Disease

PURPOSE OF REVIEW

Esophageal peristalsis is a highly sophisticated function that involves the coordinated contraction and relaxation of striated and smooth muscles in a cephalocaudal fashion, under the control of central and peripheral neuronal mechanisms and a number of neurotransmitters. Esophageal peristalsis is determined by the balance of the intrinsic excitatory cholinergic, inhibitory nitrergic and post-inhibitory rebound excitatory output to the esophageal musculature.

RECENT FINDINGS

Dissociation of the longitudinal and circular muscle contractions characterizes different major esophageal disorders and leads to esophageal symptoms. Provocative testing during esophageal high-resolution manometry is commonly employed to assess esophageal body peristaltic reserve and underpin clinical diagnosis. Herein, we summarize the main factors that determine esophageal peristalsis and examine their role in major and minor esophageal motility disorders and eosinophilic esophagitis.

Evaluation of Esophageal Contraction Reserve Using HRM in Symptomatic Esophageal Disease

Esophageal high resolution manometry (HRM) is the gold standard for assessment of esophageal motor disorders, but motor responses to the standard 5 mL water swallow protocol may not provide precision in defining minor motor disorders. Provocative maneuvers, particularly multiple rapid swallows (MRS), have been used to assess deglutitive inhibition during the repetitive swallows, and the contractile response following the final swallow of the sequence. The augmentation of esophageal smooth muscle contraction following MRS is termed contraction reserve. This is determined as the ratio between esophageal body contraction vigor (distal contractile integral, DCI) following MRS to the mean DCI after single swallows, which is ≥1 in the presence of contraction reserve. Reliable assessment of contraction reserve requires the performance of 3 MRS maneuvers during HRM. Absence of contraction reserve is associated with a higher likelihood of late postfundoplication dysphagia and may correlate with higher esophageal reflux burden on ambulatory reflux monitoring. Esophageal motor responses to abdominal compression, functional lumen imaging probe (FLIP) balloon distension, and pharmacologic testing (using edrophonium and cisapride) may correlate with contraction reserve. Other provocative tests useful during HRM include rapid drink challenge, solid and viscous swallows, and standardized test meals, which are more useful in evaluation of esophageal outflow obstruction and dysphagia syndromes than in identification of contraction reserve. Provocative maneuvers have been recommended as part of routine HRM protocols, and while useful clinical information can be gleaned from these maneuvers, further research is necessary to determine the precise role of provocative testing in clinical esophagology.

Topographical plots of esophageal distension and contraction: effects of posture on esophageal peristalsis and bolus transport

Each swallow induces a wave of inhibition followed by contraction in the esophagus. Unlike contraction, which can easily be measured in humans using high-resolution manometry (HRM), inhibition is difficult to measure. Luminal distension is a surrogate of the esophageal inhibition. The aim of this study was to determine the effect of posture on the temporal and quantitative relationship between distension and contraction along the entire length of the esophagus in normal healthy subjects by using concurrent HRM, HRM impedance (HRMZ), and intraluminal ultrasound (US). Studies were conducted in 15 normal healthy subjects in the supine and Trendelenburg positions. Both manual and automated methods were used to extract quantitative pressure and impedance-derived features from the HRMZ recordings. Topographical plots of distension and contraction were visualized along the entire length of the esophagus. Distension was also measured from the US images during 10-ml swallows at 5 cm above the lower esophageal sphincter. Each swallow was associated with luminal distension followed by contraction, both of which traversed the esophagus in a sequential/peristaltic fashion. Luminal distension (US) and esophageal contraction amplitude were greater in the Trendelenburg compared with the supine position. Length of esophageal breaks (in the transition zone) were reduced in the Trendelenburg position. Change in posture altered the temporal relationship between distension and contraction, and bolus traveled closer to the esophageal contraction in the Trendelenburg position. Topographical contraction-distension plots derived from HRMZ recordings is a novel way to visualize esophageal peristalsis. Future studies should investigate if abnormalities of esophageal distension are the cause of functional dysphagia. NEW & NOTEWORTHY Ascending contraction and descending inhibition are two important components of peristalsis. High-resolution manometry only measures the contraction phase of peristalsis. We measured esophageal distension from intraluminal impedance recordings and developed novel contraction-distension topographical plots to prove that similar to contraction, distension also travels in a peristaltic fashion. Change in posture from the supine to the Trendelenburg position also increased the amplitude of esophageal distension and contraction and altered the temporal relationship between distension and contraction.

Genesis of Esophageal Pressurization and Bolus Flow Patterns in Patients With Achalasia Esophagus

BACKGROUND & AIMS

In patients with achalasia esophagus, swallows induce simultaneous pressure waves known as esophageal pressurization. We studied the mechanism of esophageal pressurization and bolus flow patterns in patients with type 2 or type 3 achalasia.

METHODS

We recorded high-resolution manometry with impedance and intraluminal ultrasound images concurrently in patients with type 2 achalasia (n = 6) or type 3 achalasia (n = 8) and in 10 healthy subjects (controls) during swallows of 5 mL of 0.5N saline. For each swallow, the ultrasound image was aligned with the pressure and impedance tracings to determine cavity and contact pressure, bolus arrival, bolus dwell time, and changes in muscle thickness at 5 cm and 10 cm above the lower esophageal sphincter.

RESULTS

In patients with type 2 achalasia, esophageal pressurization was associated with an increase in the muscle thickness and luminal narrowing but not complete luminal closure (ie, cavity pressure). Bolus arrival time in the distal esophagus after the onset of a swallow was delayed in patients with type 3 achalasia compared with control individuals because of early luminal closure. The early luminal closure was associated with a decrease in the muscle thickness. The bolus dwell time was shorter in patients with type 3 achalasia compared with control individuals. In patients with type 3 achalasia, the onset of simultaneous pressure wave was always a cavity pressure, but during contraction there were different periods of cavity and contact pressures in association with increases in muscle thickness that resulted in bolus segmentation.

CONCLUSIONS

We observed distinct mechanisms of esophageal pressurization and bolus flow patterns in patients with type 2 or type 3 achalasia esophagus compared with control individuals. These findings will increase our understanding of the mechanisms of dysphagia.

A study of dysphagia symptoms and esophageal body function in children undergoing anti-reflux surgery

BACKGROUND

The role of high-resolution esophageal impedance manometry (HRIM) for establishing risk for dysphagia after anti-reflux surgery is unclear. We conducted a prospective study of children with primary gastroesophageal reflux (GER) disease, for whom symptoms of dysphagia were determined pre-operatively and then post-operatively and we examined for features that may predict post-operative dysphagia.

METHODS

Thirteen children (aged 6.8-15.5 years) undergoing work-up prior to 360o Nissen fundoplication were included in the study. A dysphagia score assessed symptoms at pre-operative study and post-operatively (mean 1.4 years). A HRIM procedure recorded 5-ml liquid, 5-ml viscous and 2-cm solid boluses. We assessed esophageal motility, esophago-gastric junction (EGJ) morphology, EGJ contractility and pressure-flow variables indicative of bolus distension pressures and bolus clearance pressures. A composite pressure-flow index score was also derived.

RESULTS

Pre-operative pressure-flow index was positively correlated with post-operative dysphagia score (viscous bolus r = 0.771, p < 0.005). Of three variables that comprise the pressure-flow index, the ramp pressure measured during bolus clearance was the main driver of the effect seen (viscous bolus r = 0.819, p < 0.005).

CONCLUSIONS

In order to mitigate symptoms in relation to anti-reflux surgery, dysphagia symptoms and esophageal function need to be pre-operatively assessed. In patients with normal motility, an elevated pressure-flow index may predict post-operative dysphagia.

Pharyngeal swallowing and oesophageal motility during a solid meal test: a prospective study in healthy volunteers and patients with major motility disorders

BACKGROUND

The factors that determine how people eat when they are healthy or have disease have not been defined. We used high resolution manometry (HRM) to assess pharyngeal swallowing and oesophageal motility during ingestion of a solid test meal (STM) in healthy volunteers and patients with motility disorders.

METHODS

This study was based at University Hospital Zurich (Zürich, Switzerland). Healthy volunteers who responded to an advertisement completed HRM with ten single water swallows (SWS) in recumbent and upright positions followed by a 200 g rice STM in the upright position. Healthy volunteers were stratified for age and sex to ensure a representative population. For comparison, consecutive patients with major motility disorders on SWS and patients with dysphagia but no major motility disorders on SWS (disease controls) were selected from a database that was assembled prospectively; the rice meal data were analysed retrospectively. During STM, pharyngeal swallows were timed and oesophageal contractions were classified as representing normal motility or different types of abnormal motility in accordance with established metrics. Factors that could potentially be associated with eating speed were investigated, including age, sex, body-mass index, and presence of motility disorder. We compared diagnoses based on SWS findings, assessed with the Chicago Classification v3.0, with those based on STM findings, assessed with the Chicago Classification adapted for solids. These studies are registered with ClinicalTrials.gov, numbers NCT02407938 and NCT02397616.

FINDINGS

Between April 2, 2014, and May 13, 2015, 72 healthy volunteers were recruited and underwent HRM. Additionally, we analysed data from 54 consecutive patients with major motility disorders and 53 with dysphagia but no major motility disorders recruited between April 2, 2013, and Dec 18, 2014. We found important variations in oesophageal motility and eating speed during meal ingestion in healthy volunteers and patients. Increased time between swallows was accompanied by more effective oesophageal contractions (in healthy volunteers, 20/389 [5%] effective swallows at <4 s between swallows vs 586/900 [65%] effective swallows at >11 s between swallows, p<0·0001). Obstructive, spastic, or hypercontractile swallows were rare in healthy volunteers (total <1%). Patients with motility disorders ate slower than healthy volunteers (14·95 g [IQR 11-25] per min vs 32·9 g [25-40] per min, p<0·0001) and pathological oesophageal motility were reproduced when patients consumed the STM. In healthy volunteers, eating speed was associated only with frequency of swallows (slope 2·5 g per min per pharyngeal swallow per min [95% CI 1·1-4·0], p=0·0009), whereas in patients with dysphagia, it was correlated with frequency of effective oesophageal contractions (6·4 g per min per effective contraction per min [4·3-8·5], p<0·0001). Diagnostic agreement was good between the HRM with SWS and rice STM (intra-class correlation coefficient r=0·81, 95% CI 0·74-0·87, p<0·0001).

INTERPRETATION

Our results show normative values for pharyngeal swallowing and oesophageal motility in healthy volunteers. Detailed analysis of HRM data acquired during an STM shows that the rate-limiting factor for intake of solids in health is the frequency of pharyngeal swallowing and not oesophageal contractility. The reverse is true in patients with oesophageal motility disorders, in whom the frequency of effective oesophageal contractions determines eating speed.

FUNDING

University Hospital Zurich.

Intra-bolus pressure and esophagogastric gradient, assessed with high-resolution manometry, are associated with acid exposure and proximal migration of refluxate

Trans-sphincteric pressure gradient (TSPG) seems to play a relevant role in eliciting refluxes during transient lower esophageal sphincter relaxations (TLESRs). Intra-bolus pressure (IBP) is considered to be correlated to esophageal wall tone. We aimed to evaluate the relationship between IBP, TSPG during TLESRs and the dynamic properties of refluxate in gastroesophageal reflux disease. Sixteen non-erosive reflux disease (NERD), 10 erosive disease (ERD) patients and 12 healthy volunteers (HVs), underwent 24-hour impedance-pH monitoring and combined high-resolution manometry-impedance before and 60 minutes. After a meal, ERD patients presented a significantly lower mean IBP (4.7 ± 1.6 mmHg) respect to NERD patients (8.9 ± 2.8 mmHg) and HVs (9.2 ± 3.2 mmHg). NERD patients with physiological abnormal acid exposure time showed a mean IBP (10.4 ± 3.1 mmHg) significantly higher than that in NERD with pathological abnormal acid exposure time (5.1 ± 1.5 mmHg). The TSPG value was significantly higher during TLESRs accompanied by reflux than during TLESRs not associated with reflux, both in patients and in HVs. A significant direct correlation was found between IBP, TSPG and proximal spread of refluxes in patients and in HVs. Gastroesophageal reflux disease patients display different degrees of esophageal distension. An increased compliance of the distal esophagus may accommodate larger volumes of refluxate and likely facilitates the injuries development. Higher TSPG values appear to facilitate the occurrence of refluxes during TLESRs. In patients with NERD, higher TSPG and IBP values favor proximal spread of refluxate and hence may play a relevant role in symptom generation.

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.

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

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

Identification of Quality Measures for Performance of and Interpretation of Data From Esophageal Manometry

BACKGROUND & AIMS

Esophageal manometry is the standard for the diagnosis of esophageal motility disorders. Variations in the performance and interpretation of esophageal manometry result in discrepant diagnoses and unnecessary repeated procedures, and could have negative effects on patient outcomes. We need a method to benchmark the procedural quality of esophageal manometry; as such, our objective was to formally develop quality measures for the performance and interpretation of data from esophageal manometry.

METHODS

We used the RAND University of California Los Angeles Appropriateness Method (RAM) to develop validated quality measures for performing and interpreting esophageal manometry. The research team identified potential quality measures through a literature search and interviews with experts. Fourteen experts in esophageal manometry ranked the proposed quality measures for appropriateness via a 2-round process on the basis of RAM.

RESULTS

The experts considered a total of 29 measures; 17 were ranked as appropriate and were as follows: related to competency (2), assessment before the esophageal manometry procedure (2), the esophageal manometry procedure itself (3), and interpretation of data (10). The data interpretation measures were integrated into a single composite measure. Eight measures therefore were found to be appropriate quality measures for esophageal manometry . Five other factors also were endorsed by the experts, although these were not ranked as appropriate quality measures.

CONCLUSIONS

We identified 8 formally validated quality measures for the performance and interpretation of data from esophageal manometry on the basis of RAM. These measures represent key aspects of a high-quality esophageal manometry study and should be adopted uniformly. These measures should be evaluated in clinical practice to determine how they affect patient outcomes.

Effects of remifentanil on esophageal motility: a double-blind, randomized, cross-over study in healthy volunteers

BACKGROUND

Recent studies have shown that remifentanil increases the risk of aspiration and induces subjective swallowing difficulties. The mechanisms are not completely understood. Here, we investigated whether remifentanil impairs esophageal motility and hypothesized that this is one possible underlying mechanism. Naloxone was used to evaluate whether the effects of remifentanil are mediated through opioid receptors. We also examined subjective swallowing difficulties and the influence of metoclopramide on remifentanil-induced effects.

METHODS

Fourteen healthy volunteers participated in a double-blind, randomized, cross-over trial at the University Hospital in Örebro, Sweden. They were studied on two different occasions, during which they were randomly assigned to receive either naloxone given as a bolus of 6 μg/kg followed by an infusion of 0.1 μg/kg/min, or saline 5 min before target-controlled infusions of remifentanil at three target-site concentrations: 1, 2, and 3 ng/ml. On both occasions, 0.2 mg/kg metoclopramide was given before the final measurement. Five swallows were performed during each measuring condition, and the metrics defining esophageal motility were measured by high-resolution manometry. Outcomes were differences in the metrics at baseline vs. during remifentanil infusion, with naloxone vs. placebo, and with remifentanil before and after metoclopramide administration. Differences in swallowing difficulties were also recorded.

RESULTS

Remifentanil decreased swallow-evoked esophagogastric junction relaxation and the latency time of esophageal peristalsis. There were no significant effects of naloxone or metoclopramide on remifentanil-induced effects, and we detected no differences in swallowing difficulties.

CONCLUSIONS

Remifentanil induces dysfunction of esophageal motility; this may contribute to the elevated risk of regurgitation and aspiration.

Measurement of peak esophageal luminal cross-sectional area utilizing nadir intraluminal impedance

BACKGROUND

Multichannel intraluminal impedance (MII) is currently used to monitor gastroesophageal reflux and esophageal bolus clearance. We describe a novel methodology to measure maximal luminal cross-sectional area (CSA) during bolus transport from MII measurements.

METHODS

Studies were conducted in-vitro (test tubes) and in-vivo (healthy subjects). Concurrent MII, high resolution manometry, and intraluminal ultrasound (US) images were recorded 7-cm above the lower esophageal sphincter. Swallows with two concentrations of saline, 0.1 and 0.5 N, of bolus volumes 5, 10, and 15 cc were performed. The CSA was estimated by solving two algebraic Ohm's law equations, resulting from the two saline solutions. The CSA calculated from impedance method was compared with the CSA measured from the intraluminal US images.

KEY RESULTS

The CSA measured in duplicate from B-mode US images showed a mean difference between the two manual delineations to be near zero, and the repeatability coefficient was within 7.7% of the mean of the two CSA measurements. The calculated CSA from the impedance measurements strongly correlated with the US measured CSA (R(2) ≅ 0.98). A detailed statistical analysis of the impedance and US measured CSA data indicated that the 95% limits of agreement between the two methods ranged from -9.1 to 13 mm(2) . The root mean square error of the two measurements was 4.8% of the mean US-measured CSA.

CONCLUSIONS & INFERENCES

We describe a novel methodology to measure peak esophageal luminal CSA from the nadir impedance during peristalsis. Further studies are needed to determine if it is possible to measure patterns of luminal distension during peristalsis across the entire length of the esophagus from the MII recordings.

Esophageal motor function: technical aspects of manometry

High-resolution manometry (HRM) has advanced the understanding of esophageal peristaltic mechanisms and has simplified esophageal motor testing. In this article the technical aspects of HRM are addressed, focusing on test protocols, in addition to concerns and pitfalls in performing esophageal motor studies. Specifically, catheter positioning, equipment-related artifacts, basal data acquisition, adequate swallows, and provocative maneuvers are discussed.

Defective mucosal movement at the gastroesophageal junction in patients with gastroesophageal reflux disease

BACKGROUND

Little is known about the role of muscularis mucosa at the gastroesophageal junction (GEJ).

AIM

To evaluate the movement of the mucosa/muscularis-mucosa/submucosa (MMS) at the GEJ in normal subjects and in patients with gastroesophageal reflux disease (GERD).

METHODS

Gastroesophageal junctions of 20 non-GERD subjects and 10 patients with GERD were evaluated during 5 mL swallows using two methods: in high-resolution endoluminal ultrasound and manometry, the change in the GEJ luminal pressures and cross-sectional area of esophageal wall layers were measured; in abdominal ultrasound, the MMS movement at the GEJ was analyzed.

RESULTS

Endoluminal ultrasound: In the non-GERD subjects, the gastric MMS moved rostrally into the distal esophagus at 2.17 s after the bolus first reached the GEJ. In GERD patients, the gastric MMS did not move rostrally into the distal esophagus. The maximum change in cross-sectional area of gastroesophageal MMS in non-GERD subjects and in GERD patients was 289 % and 183%, respectively. Abdominal ultrasound: In non-GERD subjects, the gastric MMS starts to move rostrally significantly earlier and to a greater distance than muscularis propria (MP) after the initiation of the swallow (1.75 vs. 3.00 s) and (13.97 vs. 8.91 mm). In GERD patients, there is no significant difference in the movement of gastric MMS compared to MP (6.74 vs. 6.09 mm). The independent movement of the gastric MMS in GERD subjects was significantly less than in non-GERD subjects.

CONCLUSION

In non-GERD subjects, the gastric MMS moves rostrally into the distal esophagus during deglutitive inhibition and forms a barrier. This movement of the MMS is defective in patients with GERD.

Relationship between multiple water swallows and gastroesophageal reflux in patients with normal esophageal motility

Multiple water swallows (MWS) stimulates neural inhibition, resulting in abolition of contractions in the esophageal body and complete lower esophageal sphincter relaxation, which is followed by peristalsis and the lower esophageal sphincter contraction. We assessed the relationship between MWS and gastroesophageal reflux in patients with esophageal symptoms and with normal findings by high-resolution manometry (HRM). We retrospectively reviewed the clinical records of patients who underwent HRM and a 24-hour ambulatory impedance-pH study. Correlation between the findings of the impedance-pH study and abnormal MWS responses without motility disorders was evaluated. Independent t-tests were used for statistical analysis. Of 28 patients, 20 (71%) had abnormal MWS responses: four (20%) had abnormal responses during MWS, six (30%) had abnormal responses after MWS, and 10 (50%) had abnormal responses both during and after MWS. Total acid exposure times were significantly longer in patients with abnormal MWS responses than in patients with normal MWS responses. In particular, upright acid exposure time and all reflux percent times were significantly longer in patients with abnormal MWS responses. However, bolus clearance time and longest reflux episode were not different between the two groups. Abnormal MWS responses predicted increased acid exposure times in patients with normal findings of HRM by the Chicago classification.

Effects of viscosity and volume on the patterns of esophageal motility in healthy adults using high-resolution manometry

The purpose of this study was to determine the effects of age, sex, body mass index (BMI), viscosity, and volume on esophageal motility using high-resolution manometry (HRM). Manometric studies were performed on 60 asymptomatic volunteers (27 men and 33 women, age: 19-56 years) while in a supine position. Manometric protocol included 10 water swallows (5 cc), 10 jelly swallows (5 cc), and 1 water swallow (20 cc). Evaluation of HRM parameters including length of proximal pressure trough (PPT length), distal latency (DL), contractile front velocity (CFV), distal contractile integral (DCI), and 4-second integrated relaxation pressure (IRP) was performed using MATLAB. Significant differences were noted in median IRP between water 5 cc (median 7.2 mmHg [range 5.5-9.6]), jelly 5 cc (median 6.0 mmHg [range 3.8-8.0]), and water 20 cc {(Median 4.8 mmHg [range 3.3-7.4]), P < 0.01}. DL were significantly different between water 5 cc, jelly 5 cc, and water 20 cc (P < 0.01), and in terms of PPT, proportions of small (2 cm ≤ < 5 cm) and large (5 cm≤) break for jelly 5 cc were significantly higher than those for the water 5 cc swallow (P < 0.05). Furthermore, DCI increased with age for water 5 cc, and a significant negative correlation was noticed between proportions of small break and BMI for water 5 cc. Manometric measurements vary depending on age, BMI, viscosity, and volume. These findings need to be taken into account in the interpretation of manometry results.

Esophageal motility in troublesome belching

CONTEXT

Supragastric belches are the main determinants of troublesome belching symptoms. In supragastric belches, air is rapidly brought into the esophagus and is immediately followed by a rapid expulsion before it has reached the stomach.

OBJECTIVE

To evaluate the esophageal contraction and transit after wet swallows in patients with troublesome belching.

METHODS

Esophageal contraction and transit were evaluated in 16 patients with troublesome belching and 15 controls. They were measured at 5, 10, 15, and 20 cm from the lower esophageal sphincter (LES) by a solid state manometric and impedance catheter. Each subject swallowed five 5 mL boluses of saline.

RESULTS

The amplitude, duration and area under the curve of contractions were similar in patients with troublesome belching and control subjects. The total esophageal bolus transit time was 6.2 (1.8) s in patients with troublesome belching and 6.1 (2.3) s in controls (P=0.55). The bolus presence time was longer in controls than in patients at 5 cm from the LES [controls: 6.0 (1.1) s, patients: 4.9 (1.2) s, P=0.04], without differences at 10, 15 and 20 cm from the LES. The bolus head advanced time was longer in patients than controls from 20 cm to 15 cm [controls: 0.1 (0.1) s, patients: 0.7(0.8)s, P=0.01] and from 15 cm to 10 cm [controls: 0.3 (0.1) s, patients: 1.6 (2.6) s, P=0.01] of the LES, without difference from 10 cm to 5 cm [controls: 0.7 (0.3) s, patients: 1.0 (1.1) s, P=0.37]. There was no difference in segment transit time.

CONCLUSION

There was no difference in esophageal contractions between patients with troublesome belching and controls. The swallowed bolus went slower into the proximal and middle esophageal body in patients than in control, but cross the distal esophageal body faster in patients than in controls.

Multiple rapid swallow responses during esophageal high-resolution manometry reflect esophageal body peristaltic reserve

OBJECTIVES

Dysphagia may develop following antireflux surgery as a consequence of poor esophageal peristaltic reserve. We hypothesized that suboptimal contraction response following multiple rapid swallows (MRS) could be associated with chronic transit symptoms following antireflux surgery.

METHODS

Wet swallow and MRS responses on esophageal high-resolution manometry (HRM) were characterized collectively in the esophageal body (distal contractile integral (DCI)), and individually in each smooth muscle contraction segment (S2 and S3 amplitudes) in 63 patients undergoing antireflux surgery and in 18 healthy controls. Dysphagia was assessed using symptom questionnaires. The MRS/wet swallow ratios were calculated for S2 and S3 peak amplitudes and DCI. MRS responses were compared in patients with and without late postoperative dysphagia following antireflux surgery.

RESULTS

Augmentation of smooth muscle contraction (MRS/wet swallow ratios >1.0) as measured collectively by DCI was seen in only 11.1% with late postoperative dysphagia, compared with 63.6% in those with no dysphagia and 78.1% in controls (P≤0.02 for each comparison). Similar results were seen with S3 but not S2 peak amplitude ratios. Receiver operating characteristics identified a DCI MRS/wet swallow ratio threshold of 0.85 in segregating patients with late postoperative dysphagia from those with no postoperative dysphagia with a sensitivity of 0.67 and specificity of 0.64.

CONCLUSIONS

Lack of augmentation of smooth muscle contraction following MRS is associated with late postoperative dysphagia following antireflux surgery, suggesting that MRS responses could assess esophageal smooth muscle peristaltic reserve. Further research is warranted to determine if antireflux surgery needs to be tailored to the MRS response.

Normative data of high-resolution impedance manometry in the Chinese population

BACKGROUND AND AIM

Current normative data of high-resolution manometry have been obtained from Western populations, and esophageal motility disorders have been categorized using Chicago classification. However, the utility of high-resolution impedance manometry (HRiM) in the Chinese population has not been evaluated. The study aimed to investigate the normal reference of esophageal motility in healthy volunteers (as defined by Chicago classification) using HRiM.

METHODS

Healthy, fasted volunteers underwent HRiM in a supine position with 10 liquid swallows and 10 viscous swallows. Integrated relaxation pressure (IRP), distal contractile integral (DCI), contractile front velocity (CFV), and distal latency were calculated. The interquartile ranges and the 95th percentile range for each metric were obtained.

RESULTS

Forty-two healthy volunteers were enrolled with 411 total liquid swallows and 398 viscous swallows available for analysis. A 20.5 mmHg of IRP and a 3195 mmHg·s·cm of DCI as the 95th percentile for liquid swallows were established. Using the reference range defined by Chicago classification, 6.3% (26/411) weak peristalsis and 0.7% (3/411) failed peristalsis for liquid swallows were observed; 12 (28.6%, 12/42) and 2 (4.7%, 2/42) individuals were diagnosed as esophagogastric junction outflow obstruction and weak peristalsis for liquid swallows. Compared with liquid swallows, viscous swallows had a decreased IRP (P = 0.000) and CFV (P = 0.000), and an unchanged DCI (P = 0.211).

CONCLUSIONS

HRiM normative data of both liquid and viscous swallows from healthy Chinese volunteers were established. The IRP and CFV were significantly decreased in the viscous swallows compared with those of the liquid swallows.

Evaluation of Esophageal Motor Function With High-resolution Manometry

For several decades esophageal manometry has been the test of choice to evaluate disorders of esophageal motor function. The recent introduction of high-resolution manometry for the study of esophageal motor function simplified performance of esophageal manometry, and revealed previously unidentified patterns of normal and abnormal esophageal motor function. Presentation of pressure data as color contour plots or esophageal pressure topography led to the development of new tools for analyzing and classifying esophageal motor patterns. The current standard and still developing approach to do this is the Chicago classification. While this methodical approach is improving our diagnosis of esophageal motor disorders, it currently does not address all motor abnormalities. We will explore the Chicago classification and disorders that it does not address.

Anatomy and physiology of the esophageal body

The primary role of the esophagus is to propel swallowed food or fluid into the stomach and to prevent or clear gastroesophageal reflux. This function is achieved by an organized pattern that involves a sensory pathway, neural reflexes, and a motor response that includes esophageal tone, peristalsis, and shortening. The motor function of the esophagus is controlled by highly complex voluntary and involuntary mechanisms. There are three different functional areas in the esophagus: the upper esophageal sphincter, the esophageal body, and the LES. This article focused on anatomy and physiology of the esophageal body.

Evaluation of esophageal contractile propagation using esophageal pressure topography

BACKGROUND

High-resolution manometry and esophageal pressure topography have enhanced our ability to analyze esophageal motor disturbances by improving the detail and accuracy of measurements of peristaltic activity.This has been extremely helpful in the evaluation of disorders of rapid propagation as the technique is able to define important time points and physiologic landmarks that are crucial in defining peristaltic velocity and latency intervals.

PURPOSE

The goal of the current review will be to assess how esophageal pressure topography has impacted our ability to define important phenotypes of rapid propagation. Additionally, this review will also be utilized to complement the description of the Chicago Classification of Esophageal Motor Disorders, which is presented in this supplement issue.

Technical aspects of clinical high-resolution manometry studies

A number of commercial and research systems are available for making high-resolution manometry recordings. purpose: In this document, we review the standard equipment, patient preparation and routine protocol for high-resolution manometry. The major differences between HRM systems lie in the method of signal transduction, with solid-state catheter systems recording form intraluminal transducers and water perfusion systems recording pressures from external transducers via a perfused silicone catheter. The variations in recording systems result in different mechanical and electrical characteristics which dictate different techniques for setting up and using equipment. These issues are relevant in terms of costs and day to day management, but have little clinical significance. After the equipment is prepared for a manometric study, the esophagus is intubated transnasally with the manometric catheter and the catheter is positioned so that the UES and LES/diaphragm are visualized on the recording screen. The subject then undergoes 10 5 ml water swallows in the supine position. Manometric data may be integrated with other data streams such as multichannel impedance or images from fluoroscopy to increase the power of the technique in difficult cases.

Chicago classification criteria of esophageal motility disorders defined in high resolution esophageal pressure topography

BACKGROUND

The Chicago Classification of esophageal motility was developed to facilitate the interpretation of clinical high resolution esophageal pressure topography (EPT) studies, concurrent with the widespread adoption of this technology into clinical practice. The Chicago Classification has been an evolutionary process, molded first by published evidence pertinent to the clinical interpretation of high resolution manometry (HRM) studies and secondarily by group experience when suitable evidence is lacking.

PURPOSE

This publication summarizes the state of our knowledge as of the most recent meeting of the International High Resolution Manometry Working Group in Ascona, Switzerland in April 2011. The prior iteration of the Chicago Classification was updated through a process of literature analysis and discussion. The major changes in this document from the prior iteration are largely attributable to research studies published since the prior iteration, in many cases research conducted in response to prior deliberations of the International High Resolution Manometry Working Group. The classification now includes criteria for subtyping achalasia, EGJ outflow obstruction, motility disorders not observed in normal subjects (Distal esophageal spasm, Hypercontractile esophagus, and Absent peristalsis), and statistically defined peristaltic abnormalities (Weak peristalsis, Frequent failed peristalsis, Rapid contractions with normal latency, and Hypertensive peristalsis). The Chicago Classification is an algorithmic scheme for diagnosis of esophageal motility disorders from clinical EPT studies. Moving forward, we anticipate continuing this process with increased emphasis placed on natural history studies and outcome data based on the classification.

A novel pattern of longitudinal muscle contraction with subthreshold pharyngeal stimulus: a possible mechanism of lower esophageal sphincter relaxation

A subthreshold pharyngeal stimulus induces lower esophageal sphincter (LES) relaxation and inhibits progression of ongoing peristaltic contraction in the esophagus. Recent studies show that longitudinal muscle contraction of the esophagus may play a role in LES relaxation. Our goal was to determine whether a subthreshold pharyngeal stimulus induces contraction of the longitudinal muscle of the esophagus and to determine the nature of this contraction. Studies were conducted in 16 healthy subjects. High resolution manometry (HRM) recorded pressures, and high frequency intraluminal ultrasound (HFIUS) images recorded longitudinal muscle contraction at various locations in the esophagus. Subthreshold pharyngeal stimulation was induced by injection of minute amounts of water in the pharynx. A subthreshold pharyngeal stimulus induced strong contraction and caudal descent of the upper esophageal sphincter (UES) along with relaxation of the LES. HFIUS identified longitudinal muscle contraction of the proximal (3-5 cm below the UES) but not the distal esophagus. Pharyngeal stimulus, following a dry swallow, blocked the progression of dry swallow-induced peristalsis; this was also associated with UES contraction and descent along with the contraction of longitudinal muscle of the proximal esophagus. We identify a unique pattern of longitudinal muscle contraction of the proximal esophagus in response to subthreshold pharyngeal stimulus, which we propose may be responsible for relaxation of the distal esophagus and LES through the stretch sensitive activation of myenteric inhibitory motor neurons.

Deglutitive inhibition, latency between swallow and esophageal contractions and primary esophageal motor disorders

Swallowing induces an inhibitory wave that is followed by a contractile wave along the esophageal body. Deglutitive inhibition in the skeletal muscle of the esophagus is controlled in the brain stem whilst in the smooth muscle, an intrinsic peripheral control mechanism is critical. The latency between swallow and contractions is determined by the pattern of activation of the inhibitory and excitatory vagal pathways, the regional gradients of inhibitory and excitatory myenteric nerves, and the intrinsic properties of the smooth muscle. A wave of inhibition precedes a swallow-induced peristaltic contraction in the smooth muscle part of the human oesophagus involving both circular and longitudinal muscles in a peristaltic fashion. Deglutitive inhibition is necessary for drinking liquids which requires multiple rapid swallows (MRS). During MRS the esophageal body remains inhibited until the last of the series of swallows and then a peristaltic contraction wave follows. A normal response to MRS requires indemnity of both inhibitory and excitatory mechanisms and esophageal muscle. MRS has recently been used to assess deglutitive inhibition in patients with esophageal motor disorders. Examples with impairment of deglutitive inhibition are achalasia of the LES and diffuse esophageal spasm.

Distal esophageal spasm in high-resolution esophageal pressure topography: defining clinical phenotypes

BACKGROUND

The manometric diagnosis of distal esophageal spasm (DES) uses "simultaneous contractions" as a defining criterion, ignoring the concept of short latency distal contractions as an important feature. Our aim was to apply standardized metrics of contraction velocity and latency to high-resolution esophageal pressure topography (EPT) studies to refine the diagnosis of DES.

METHODS

Two thousand consecutive EPT studies were analyzed for contractile front velocity (CFV) and distal latency to identify patients potentially having DES. Normal limits for CFV and distal latency were established from 75 control subjects. Clinical data of patients with reduced distal latency and/or rapid CFV were reviewed.

RESULTS

Of 1070 evaluable patients, 91 (8.5%) had a high CFV and/or low distal latency. Patients with only rapid contractions (n = 186 [17.4%] using conventional manometry criteria; n = 85 [7.9%] using EPT criteria) were heterogeneous in diagnosis and symptoms, with the majority ultimately categorized as weak peristalsis or normal. In contrast, 96% of patients with premature contraction had dysphagia, and all (n = 24; 2.2% overall) were ultimately managed as spastic achalasia or DES.

CONCLUSIONS

The current DES diagnostic paradigm focused on "simultaneous contractions" identifies a large heterogeneous set of patients, most of whom do not have a clinical syndrome suggestive of esophageal spasm. Incorporating distal latency into the diagnostic algorithm of EPT studies improves upon this by isolating disorders of homogeneous pathophysiology: DES with short latency and spastic achalasia. We hypothesize that prioritizing measurement of distal latency will refine the management of these disorders, recognizing that outcomes trials are necessary.

Regional functional specialization and inhibitory nitrergic and nonnitrergic coneurotransmission in the human esophagus

The aim of this study was to explore the myenteric mechanisms of control of human esophageal motility and the effect of nitrergic and nonnitrergic neurotransmitters. Human circular esophageal strips were studied in organ baths and with microelectrodes. Responses following electrical field stimulation (EFS) of enteric motoneurons (EMNs) or through nicotinic acetylcholine receptors were compared in the esophageal body (EB) and in clasp and sling regions in the lower esophageal sphincter (LES). In clasp LES strips: 1) sodium nitroprusside (1 nM to 100 μM), adenosine-5'-[β-thio]diphosphate trilithium salt (1-100 μM), and vasoactive intestinal peptide (1 nM to 1 μM) caused a relaxation; 2) 1 mM N(ω)-nitro-L-arginine (L-NNA) shifted the EFS "on"-relaxation to an "off"-relaxation, partly antagonized by 10 μM 2'-deoxy-N(6)-methyladenosine 3',5'-bisphosphate tetrasodium salt (MRS2179) or 10 U/ml α-chymotrypsin; and 3) nicotine-relaxation (100 μM) was mainly antagonized by L-NNA, and only partly by MRS2179 or α-chymotrypsin. In sling LES fibers, EFS and nicotine relaxation was abolished by L-NNA. In the EB, L-NNA blocked the latency period, and MRS2179 reduced "off"-contraction. The amplitude of cholinergic contraction decreased from the EB to both LES sides. EFS induced a monophasic inhibitory junction potential in clasp, sling, and EB fibers abolished by L-NNA. Our study shows a regional specialization to stimulation of EMNs in the human esophagus, with stronger inhibitory responses in clasp LES fibers and stronger cholinergic excitatory responses in the EB. Inhibitory responses are mainly triggered by nitrergic EMNs mediating the inhibitory junction potentials in the LES and EB, EFS on-relaxation in clasp and sling LES sides, and latency in the EB. We also found a minor role for purines (through P2Y(1) receptors) and vasoactive intestinal peptide-mediating part of nonnitrergic clasp LES relaxation.

Swallow induces a peristaltic wave of distension that marches in front of the peristaltic wave of contraction

BACKGROUND

Current understanding is that swallow induces simultaneous inhibition of the entire esophagus followed by a sequential wave of contraction (peristalsis). We observed a pattern of luminal distension preceding contraction which suggested that inhibition may also traverses in a peristaltic fashion. Our aim is to determine the relationship between contraction and luminal distension during bolus transport.

METHODS

Eight subjects using two solid-state pressure and two ultrasound (US) transducers were studied. Synchronous pressure and US images were obtained with wet swallows and after edrophonium and atropine. Luminal cross-sectional area (CSA) at 2 cm and 12 cm above the lower esophageal sphincter (LES) were recorded. Relationship between pressure and CSA at each site, propagation velocity of peak pressure and peak distension waves were determined. Fluoroscopy coupled with manometry was also performed in five normal subjects.

KEY RESULTS

Esophageal distension precedes contraction wave at both-recorded sites. During distension, esophageal pressure remains constant while luminal CSA increases significantly. The onset and the peak of distension wave traverses in a peristaltic fashion between both sites. A tight coupling exists between the peak distension and peak contraction waves with similar velocities (3.7 cm s(-1) and 3.6 cm s(-1)) of propagation. The degree of distension is greater at 2 cm compared to 12 cm. Atropine and edrophonium reduced and increased the contraction pressure respectively, without affecting the distension wave. Fluoroscopic study confirmed that the wave of distension traverses the esophagus in a peristaltic fashion.

CONCLUSIONS & INFERENCES

Distension and contraction waves are tightly coupled to each other and both traverse in a peristaltic fashion.

The role of delayed gastric emptying and impaired oesophageal body motility

Delayed gastric emptying in a variable proportion of patients with gastro-oesophageal reflux disease has been observed in most series, however a relationship between delayed gastric emptying and increased gastro-oesophageal reflux has not been convincingly demonstrated. Enhanced postprandial accommodation and delayed emptying of the proximal stomach have been described, but some controversy exists. Impaired primary peristalsis is often present especially in patients with oesophagitis and its prevalence increases with increasing severity of inflammatory mucosal lesions. Patients with gastro-oesophageal reflux disease often have defective triggering of secondary peristalsis independently of presence of oesophagitis. It is presently unclear if impaired oesophageal motility is a primary defect or an irreversible consequence of inflammation. Attempts at pharmacological improvement of impaired oesophageal motility have been so far disappointing. Patients with partially preserved neuromuscular structures need to be identified in order to select them for new prokinetic therapy.

Multiple rapid swallowing: a complementary test during standard oesophageal manometry

Multiple rapid swallowing (MRS) stimulates neural inhibition resulting in abolition of contractions in the oesophageal body (OB) and complete lower oesophageal sphincter (LOS) relaxation which is followed by peristalsis and LOS contraction. The aim of this study was to evaluate the yield of MRS to detect abnormalities in inhibitory or excitatory oesophageal mechanisms in patients with oesophageal symptoms and either normal standard manometry or ineffective oesophageal motility (IOM). MRS (five water swallows, 2 mL, separated by 2-3 s) was evaluated in 23 healthy subjects, 109 symptomatic patients with normal standard sleeve manometry and in 48 patients with IOM. Healthy subjects had complete inhibition of OB motility during MRS and a strong motor response after MRS, i.e. amplitude of OB contractions in the oesophageal body and LOS tone being higher than after single swallows. Almost 70% of patients with oesophageal symptoms and normal manometry had abnormal MRS, mainly consistent on inability to increase amplitude of OB contractions after MRS. Nearly, half of the patients with IOM were able to normalize OB contractions after MRS. MRS is a simple complementary test that can be added to standard oesophageal manometry. Two-thirds of patients with normal manometry show abnormal MRS that could potentially underlie their symptoms. A normal response to MRS in patients with severe IOM might be used to predict response to prokinetic treatment.