Sensory and motor function of the esophagus: lessons from ultrasound imaging

Clinical and high-resolution manometry of 801 patients with esophageal dysmotility, including achalasia, in relation to age

Background and Aim

Spectrum of esophageal motility disorders may differ according to age, but studies on this are scanty, contradictory, and included small number of patients. Accordingly, we retrospectively analyzed data of a large sample of patients to study the spectrum of esophageal motility disorders in relation to age, and to evaluate the clinical profile and high-resolution manometry parameters and achalasia subtypes according to Chicago IV criteria.

Methods

Of 909 patients evaluated by high-resolution water perfusion or solid-state manometry during a 3-year period, data on 801 were finally analyzed.

Results

Achalasia cardia was the commonest motility disorder of esophagus in this large study and type II was the commonest subtype. There was no difference in clinical and manometry parameters among elderly patients as compared to younger patients with achalasia. Type I achalasia patients less often had chest pain and tended to have nocturnal coughing spells more often, and patients with achalasia experiencing chest pain tended to have higher distal contractile integral (DCI) than those not having pain irrespective of age.

Conclusion

The clinical and high-resolution manometry parameters among young and elderly patients with esophageal motility disorders are quite comparable. However, these differed in relation to achalasia subtypes and symptoms. Type I achalasia patients less often had chest pain and those experiencing chest pain tended to have higher DCI values than those not having pain irrespective of age.

Endoscopic luminal impedance planimetry of the lower oesophageal sphincter and pylorus in experimental pigs: a pilot study

BACKGROUND/AIMS

The functional lumen imaging probe (FLIP) relies on the principle of impedance planimetry that enables direct measurement of intraluminal pressure, cross-sectional areas, and wall biomechanical properties. The aim of our pilot project was to introduce this method to assess function of the lower oesophageal sphincter and pyloric muscle in experimental pigs.

METHODS

All measurements were accomplished in one session in six adult female pigs (mean weight 34.2 ± 3.6 kg), using the EndoFLIP 1.0 System with EndoFLIP catheters. Five major parameters were evaluated: balloon pressure (mm Hg), estimated diameter (mm), cross-sectional area (mm2), distensibility (mm2/mm Hg), and zone compliance (mm3/mm Hg).

RESULTS

In total, 180 readings were successfully accomplished. Most of the measured values were nearing lower average figures for the lower oesophageal sphincter, and upper average figures for the pylorus in healthy humans. The porcine pyloric sphincter is composed of the Torus pyloricus. It serves as a study "gatekeeper" between the stomach and D1 duodenum, thus explaining higher pyloric readings. There was a clear trend for increasing values of CSA (cross-sectional area), diameter, and balloon pressure with increased filling balloon volumes. However, the sphincter distensibility did not change with increasing filling volumes, either for the lower oesophageal sphincter or pylorus.

CONCLUSION

Endoscopic functional luminal planimetry in experimental pigs is feasible, both for the lower oesophageal sphincter and the pylorus. This is an important starting point for future experimental endoscopic trials and pharmacology studies.

Esophageal wall compliance/stiffness during peristalsis in patients with functional dysphagia and high-amplitude esophageal contractions

Recent studies that utilized distension/contraction plots to study peristalsis reveal poor distension of the esophagus in patients with functional dysphagia and high-amplitude contractions [high-amplitude esophageal contractions (HAECs)] even though the contraction phase of peristalsis is normal in these patients. Our goal was to determine biomechanical properties of the esophageal wall and bolus flow characteristics in patients with functional dysphagia and HAEC during primary peristalsis. Studies were performed on 30 healthy subjects, 30 patients with functional dysphagia, and 25 patients with HAEC. Subjects swallowed 10 mL, 0.5 N saline bolus in the Trendelenburg position to study primary peristalsis. A custom-built software (Dplots) determined peak distension from the impedance measurements, pressure at peak distension, wall tension (pressure × radius), wall distensibility [cross-sectional area (CSA)/pressure], and bolus flow (cm3/s) in four segments of esophagus (between upper and lower esophageal sphincter). Luminal CSA of distal esophagus was smaller, and average bolus flow rate was faster in patients with functional dysphagia and HAEC. Esophageal wall distensibility, a measure of esophageal wall compliance was lower and wall tension was higher in the distal esophagus of both patient groups compared with normal subjects. Ultrasound imaging confirmed poor distension of the esophagus. A trend toward greater wall thickness at the peak of distension was found in patients with functional dysphagia compared with normal subjects. A stiffer or noncompliant esophageal wall is the reason for poor distension of the esophagus during primary peristalsis in patients with functional dysphagia and HAEC.NEW & NOTEWORTHY We studied healthy asymptomatic subject, patients with functional dysphagia (FD), and patients with high-amplitude esophageal contractions (HAEC). Our data show that in patients with HAEC and functional dysphagia, luminal distension is smaller (low luminal CSA at peak distension), intraluminal pressure is higher, and liquid bolus travels faster through the esophagus as compared with normal subjects. We conclude that patients with functional dysphagia and HAEC have a stiffer distal esophageal wall during bolus transport related to primary peristalsis.

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.

Organisation of the musculature of the rat stomach

The strengths, directions and coupling of the movements of the stomach depend on the organisation of its musculature. Although the rat has been used as a model species to study gastric function, there is no detailed, quantitative study of the arrangement of the gastric muscles in rat. Here we provide a descriptive and quantitative account, and compare it with human gastric anatomy. The rat stomach has three components of the muscularis externa, a longitudinal coat, a circular coat and an internal oblique (sling) muscle in the region of the gastro-oesophageal junction. These layers are similar to human. Unlike human, the rat stomach is also equipped with paired muscular oesophago-pyloric ligaments that lie external to the longitudinal muscle. There is a prominent muscularis mucosae throughout the stomach and strands of smooth muscle occur in the mucosa, between the glands of the corpus and antrum. The striated muscle of the oesophageal wall reaches to the stomach, unlike the human, in which the wall of the distal oesophagus is smooth muscle. Thus, the continuity of gastric and oesophageal smooth muscle bundles, that occurs in human, does not occur in rat. Circular muscle bundles extend around the circumference of the stomach, in the fundus forming a cap of parallel muscle bundles. This arrangement favours co-ordinated circumferential contractions. Small bands of muscle make connections between the circular muscle bundles. This is consistent with a slower conduction of excitation orthogonal to the circular muscle bundles, across the corpus towards the distal antrum. The oblique muscle merged and became continuous with the circular muscle close to the gastro-oesophageal junction at the base of the fundus, and in the corpus, lateral to the lesser curvature. Quantitation of muscle thickness revealed gradients of thickness of both the longitudinal and circular muscle. This anatomical study provides essential data for interpreting gastric movements.

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.

Morphologic Changes in Esophageal Body Movement During Bolus Transport After Peroral Endoscopic Myotomy in Type III Achalasia

Background/Aims

The effect of peroral endoscopic myotomy (POEM) on esophageal body movement in achalasia is poorly understood. This study aims to evaluate morphological changes in esophageal body movement after POEM in type III achalasia by analyzing intraluminal ultrasound (US) images in comparison to type I and II achalasia.

Methods

Intraluminal US images and impedance values of the distal esophagus from 47 achalasia patients who underwent POEM or pneumatic dilatation (PD) (30 patients in the POEM group and 17 patients in the PD group) with pre- and post-procedural high-resolution impedance manometry and intraluminal US examinations were analyzed. The muscle thickness (MT), muscle cross-sectional area, lumen cross-sectional area (LCSA), contractility and distensibility indices, swallow-to-distension interval, and distension duration during each bolus transport were analyzed.

Results

The MT increased and LCSA decreased significantly (P < 0.001), but the contractility index was not improved after POEM or PD in type I achalasia. Baseline MT increased and LCSA decreased significantly after POEM and PD in type II achalasia (P < 0.001). In contrast, MT and the swallow-to-distension interval decreased and the distension LCSA/duration and contractility index increased after POEM in type III achalasia (P < 0.001). In contrast to type I and II achalasia, in type III achalasia, these effects were unique to the POEM group.

Conclusions

POEM decreased the esophageal LCSA by decreasing intrabolus pressure without improving contractility in type I and II achalasia. In contrast, POEM increased esophageal body distension and contractility and improved the inhibitory process during bolus transport in type III achalasia.

Evaluation and Treatment of Patients with Persistent Reflux Symptoms Despite Proton Pump Inhibitor Treatment

Despite the exceptional efficacy of proton pump inhibitors (PPIs) in healing reflux esophagitis complicating gastroesophageal reflux disease (GERD), up to 40% of patients who take PPIs for GERD complain of persistent GERD symptoms. There is no clear consensus on the type, dosing, and duration of PPI therapy required to establish a diagnosis of PPI-refractory GERD symptoms, but most authorities do not consider patients "PPI-refractory" unless they have been on double-dose PPIs. This article discusses the mechanisms that might underlie heartburn that does not respond PPIs and an approach to the management of patients with PPI-refractory GERD symptoms.

Bolus Detection in the Proximal Esophagus Using Pulse-Echo Ultrasound: A Feasibility Study

Here, the feasibility of using nonimaging pulse-echo ultrasound as a method of noninvasively detecting a bolus in the proximal esophagus was demonstrated. To accomplish this, patient swallows were recorded on a clinical ultrasound device with research interface that allowed for collection of the pulse-echo data. These ultrasound data of the proximal esophagus were processed with a series of signal processing techniques in both the temporal and spectral domains, which revealed characteristic signatures that were unique for both liquid and food boluses compared to the normal collapsed esophageal state. Since substantial amounts of laryngopharyngeal reflux are gaseous in nature, future work will revolve around expanding the data set to include boluses of gaseous refluxate, a standardized methodology for capturing bolus events; developing automated detection tools for identifying laryngopharyngeal reflux for an extended duration; and assessing technology limitations due to user error.

Refractory Gastroesophageal Reflux Disease and Functional Heartburn

This report discusses the potential mechanisms that might underlie refractory GERD and functional heartburn, and how to distinguish among those mechanisms using a systematic evaluation that includes careful medical history, endoscopy with esophageal biopsy, esophageal manometry, and esophageal multichannel intraluminal impedance-pH monitoring. The report provides an approach to patient management that depends on the underlying mechanism identified by this systematic evaluation.

Botox injection into the lower esophageal sphincter induces hiatal paralysis and gastroesophageal reflux

Endoscopic intrasphincteric injection of Botox (ISIB) is used routinely for the treatment of achalasia esophagus and other spastic motor disorders. Studies show that the ISIB reduces the smooth muscle lower esophageal sphincter (LES) pressure. The esophageal hiatus, formed by the right crus of diaphragm, surrounds the cranial half of the LES and works like an external LES. We studied the effects of ISIB on the LES and hiatal contraction and gastroesophageal reflux (GER). Fourteen patients treated with ISIB were studied. Esophageal manometry-impedance recordings were performed before and after the ISIB. Hiatal contraction was assessed during tidal inspiration, forced inspiration, Müller's maneuver, and straight leg raise. In 6 subjects, the manometry were repeated 6-12 mo after the ISIB. The esophagogastric junction (EGJ) pressure was measured at end expiration (LES pressure) and at the peak of maneuvers (hiatal contraction). Transdiaphragmatic pressure (pdi; force of diaphragmatic contraction) was measured at the peak of forced inspiration. GER was measured from the impedance recordings. The EGJ pressure at end expiration (LES pressure) decreased significantly after the Botox injection. The peak EGJ pressure at tidal inspiration, forced inspiration, Müller's maneuver, and straight leg raise was also dramatically reduced by the ISIB. There was no effect of Botox on the pdi during forced inspiration. Seven of 10 subjects demonstrated GER during maneuvers following the ISIB. Six to 12 mo after ISIB, the LES and hiatal contraction pressure returned to the pre-ISIB levels. ISIB, in addition to decreasing LES pressure, paralyzes the esophageal hiatus (crural diaphragm) and induces GER.NEW & NOTEWORTHY The sphincter mechanism at the lower end of the esophagus comprises smooth muscle lower esophageal sphincter (LES) and skeletal muscle crural diaphragm (hiatus). Current thinking is that the endoscopic intrasphincteric injection of Botox (ISIB), used routinely for the treatment of achalasia esophagus, reduces LES pressure. Our study shows that ISIB, even though injected into the LES, diffuses into the hiatus and causes its paralysis. These findings emphasize the importance of esophageal hiatus as an important component of the antireflux barrier and that the ISIB is refluxogenic.

Cholecystokinin induces esophageal longitudinal muscle contraction and transient lower esophageal sphincter relaxation in healthy humans

Cholecystokinin (CCK) is known to cause lower esophageal sphincter (LES) relaxation through the activation of inhibitory motor neurons. CCK receptor agonists increase the frequency of transient LES relaxation through a peripheral mechanism. Recent studies show that the longitudinal muscle contraction (LMC)-related axial stretch might play a role in the LES relaxation by activating the mechanosensitive inhibitory motor neurons. The aim of our study was to determine whether the CCK-induced LES relaxation and the characteristics of LMC resemble those seen with spontaneous transient LES relaxation in humans. Nine healthy volunteers (5 Fr, 40 ± 12 yr) received escalating doses of CCK-octapeptide (CCK-8) (5, 10, 20, and 40 ng/kg). All subjects demonstrated a monophasic response to 5 ng/kg of CCK-8. In the majority of subjects, this response consisted of partial LES relaxation. All subjects showed a biphasic response to 40 ng/kg of CCK-8. The latter in most subjects consisted of 1) a period of partial relaxation followed by 2) complete LES relaxation along with crural diaphragm inhibition. The length of the esophagus decreased by 0.9 ± 0.4 cm, and muscle thickness increased by 40 ± 14% to 1.4 ± 0.2 mm ( P < 0.05) during initial partial LES relaxation. During complete LES relaxation there was greater LMC, as demonstrated by an esophageal shortening of 1.9 ± 0.5 cm and an increase in muscle thickness of 100 ± 16% ( P < 0.01). The complete phase 2 LES relaxation typically terminated with a robust after-contraction. Atropine significantly attenuated the CCK-induced esophageal LMC, prevented crural diaphragm inhibition, and abolished the phase 2 complete LES relaxation. NEW & NOTEWORTHY The phenotypic features of CCK-induced longitudinal muscle contraction (LMC), complete lower esophageal sphincter (LES) relaxation, and crural diaphragm inhibition, followed by a robust after-contraction, resemble those seen during spontaneous transient LES relaxation. A strong temporal relationship between the LMC and complete transient LES relaxation supports our hypothesis that the LMC plays an important role in the LES relaxation and crural diaphragmatic inhibition.

Esophageal shortening after rapid drink test during esophageal high-resolution manometry: A relevant finding?

Background

Esophageal shortening (ES) might be observed during high-resolution manometry (HRM), in particular after the rapid drink test (RDT). We aimed to assess its diagnostic value in patients referred for HRM.

Methods

HRM of patients without previous esophagogastric surgery or endoscopic treatment was retrospectively reviewed using the Chicago Classification v3.0. ES and pan-esophageal pressurization were analyzed during the RDT (200-ml free drinking in a sitting position).

Results

A total of 2141 cases (1291 females, mean age 54 years) were reviewed. During the RDT, ES occurred in 4% and pan-esophageal pressurization in 14% of patients. ES was almost exclusively encountered in patients with impaired esophagogastric junction relaxation or major disorders of peristalsis. Among 31 patients with ES and no definite diagnosis of achalasia, 19 had follow-up and 13 (68%) changed diagnostic category: two adenocarcinoma of the cardia, and 11 cases of atypical achalasia. The positive predictive value of ES for a significant esophageal disorder was 95%.

Conclusion

ES is rarely observed during the RDT. When present, it is associated with major motility disorders, especially achalasia. When the diagnostic criteria for achalasia are not fulfilled, further complementary examinations should be performed to rule out incomplete forms of achalasia or an infiltrative process of the cardia.

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.

Axial Movements and Length Changes of the Human Lower Esophageal Sphincter During Respiration and Distension-induced Secondary Peristalsis Using Functional Luminal Imaging Probe

Background/Aims

Efficient transport through the esophago-gastric junction (EGJ) requires synchronized circular and longitudinal muscle contraction of the esophagus including relaxation of the lower esophageal sphincter (LES). However, there is a scarcity of technology for measuring esophagus movements in the longitudinal (axial) direction. The aim of this study is to develop new analytical tools for dynamic evaluation of the length change and axial movement of the human LES based on the functional luminal imaging probe (FLIP) technology and to present normal signatures for the selected parameters.

Methods

Six healthy volunteers without hiatal hernia were included. Data were analyzed from stepwise LES distensions at 20, 30, and 40 mL bag volumes. The bag pressure and the diameter change were used for motion analysis in the LES. The cyclic bag pressure frequency was used to distinguish dynamic changes of the LES induced by respiration and secondary peristalsis.

Results

Cyclic fluctuations of the LES were evoked by respiration and isovolumetric distension, with phasic changes of bag pressure, diameter, length, and axial movement of the LES narrow zone. Compared to the respiration-induced LES fluctuations, peristaltic contractions increased the contraction pressure amplitude (P < 0.001), shortening (P < 0.001), axial movement (P < 0.001), and diameter change (P < 0.01) of the narrow zone. The length of the narrow zone shortened as function of the pressure increase.

Conclusions

FLIP can be used for evaluation of dynamic length changes and axial movement of the human LES. The method may shed light on abnormal longitudinal muscle activity in esophageal disorders.

Muscular thickness of lower esophageal sphincter and therapeutic outcomes in achalasia: A prospective study using high-frequency endoscopic ultrasound

BACKGROUND AND AIM

Patients with achalasia typically have thicker lower esophageal sphincter muscles, which can affect the distensibility of the esophagogastric junction. We aimed to assess whether these muscular features, measured using high-frequency endoscopic ultrasound, affect treatment outcomes.

METHODS

Consecutive adult patients with suspected achalasia were enrolled prospectively. They underwent a comprehensive diagnostic workup, including endoscopic ultrasound. The thickness of the lower esophageal sphincter, including the internal circular and outer longitudinal muscles, was measured using a 12-MHz ultrasonic miniprobe. Follow-up was performed at 1 month and then at 6-month intervals, after treatment. Treatment response was defined as a reduction in Eckardt score to ≤3 or an improvement in the height of the timed barium esophagogram of ≥50%.

RESULTS

Of the 29 patients who received pneumatic dilatation, all but one (96.6%) exhibited a good short-term treatment response. At an average follow-up time of 18.5 (12-55.5) months, patients who had a mid-term recurrence after pneumatic dilatation had a significantly thicker outer longitudinal muscle (1.8 [1.5-1.8] vs 0.9 [0.8-1.7] mm, P = 0.036), but not internal circular muscle (2.0 [1.9-2.5] vs 2.1 [1.2-2.7] mm, P = 0.874) or total lower esophageal sphincter (3.7 [3.5-4.4] vs 3.6 [2.0-4.1] mm, P = 0.362). Patients with an outer longitudinal muscle ≥1.3 mm thick had a significantly lower mid-term remission rate than others (36.3% vs 100%, P = 0.01).

CONCLUSION

Thickening of the outer longitudinal muscle at the lower esophageal sphincter is associated with poor mid-term treatment outcomes for achalasia patients treated with pneumatic dilatation.

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

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

A Procedure for the Automatic Analysis of High-Resolution Manometry Data to Support the Clinical Diagnosis of Esophageal Motility Disorders

OBJECTIVE

Degenerative phenomena may affect esophageal motility as a relevant social-health problem. The diagnosis of such disorders is usually performed by the analysis of data from high-resolution manometry (HRM). Inter- and intraobserver variability frequently affects the diagnosis, with potential interpretative and thus therapeutic errors, with unnecessary or worse treatments. This may be avoided with automatic procedures that minimize human intervention in data processing.

METHODS

In order to support the traditional diagnostic process, an automatic procedure was defined considering a specific physiomechanical model that is able to objectively interpret data from HRM. A training set (N = 226) of healthy volunteers and pathological subjects was collected in order to define the model parameters distributions of the different groups of subjects, providing a preliminary database. A statistical algorithm was defined for an objective identification of the patient's healthy or pathological condition by comparing patient parameters with the database.

RESULTS

A collection of HRMs including subjects of the training set has been built. Statistical relationships between parameters and pathologies have been established leading to a preliminary database. An automatic diagnosis procedure has been developed to compare model parameters of a specific patient with the database. The procedure was able to match the correct diagnosis up to 86% of the analyzed subjects.

CONCLUSION

The success rate of the automatic procedure addresses the suitability of the developed algorithms to provide a valid support to the clinicians for the diagnostic activity.

SIGNIFICANCE

The objectivity of developed tools increases the reliability of data interpretation and, consequently, patient acceptance.

Catheter-based high-frequency intraluminal ultrasound imaging is a powerful tool to study esophageal dysmotility patients

High-resolution manometry (HRM) is currently the most important diagnostic test for esophageal motility disorders, providing information on the contraction pattern of the circular muscle layer, which helps classify these esophageal motor diseases. However, with the increasing development of ultrasound, other techniques, such as high-frequency intraluminal ultrasound (HFIUS), have gained importance. This technique uses a flexible shaft with a central wire integrated into a standard endoscope, which facilitates real-time sonography. Its main utility is to provide anatomical information on the structure of the esophageal wall, including both the circular and longitudinal layers that constitute the esophageal muscularis propria. Increasing knowledge about these motility disorders has led to the hypothesis that, in addition to an abnormal contraction pattern of the circular muscle, an overall increased muscle thickness and an abnormal longitudinal muscle contraction could be added as pathophysiological factors. The increase in muscle thickness could be an important indicator of the severity of diseases, such as achalasia, distal esophageal spasm, or hypercontractile esophagus. More studies are required before definitive conclusions can be reached, but HFIUS employed simultaneously with HRM could provide a more complete and precise evaluation of these esophageal motor disorders.

Temporal and spectral properties of esophageal mucosal blood perfusion: a comparison between normal subjects and nutcracker esophagus patients

BACKGROUND

The mechanism of esophageal pain in patients with nutcracker esophagus (NE) and other esophageal motor disorders is not known. Our recent study shows that baseline esophageal mucosal perfusion, measured by laser Doppler perfusion monitoring, is lower in NE patients compared to controls. The goal of our current study was to perform a more detailed analysis of esophageal mucosal blood perfusion (EMBP) waveform of NE patients and controls to determine the optimal EMBP biomarkers that combined with suitable statistical learning models produce robust discrimination between the two groups.

METHODS

Laser Doppler recordings of 10 normal subjects (mean age 43 ± 15 years, 8 males) and 10 patients (mean age 47 ± 5.5 years., 8 males) with NE were analyzed. Time and frequency domain features were extracted from the first twenty-minute recordings of the EMBP waveforms, statistically ranked according to four independent evaluation criterions, and analyzed using two statistical learning models, namely, logistic regression (LR) and support vector machines (SVM).

KEY RESULTS

The top three ranked predictors between the two groups were the 0.5 and 0.75 perfusion quantile values followed by the surface of the EMBP power spectrum in the frequency domain. ROC curve ranking produced a cross-validated AUC (area under the curve) of 0.93 for SVM and 0.90 for LR.

CONCLUSIONS & INFERENCES

We show that as a group NE patients have lower perfusion values compared to controls, however, there is an overlap between the two groups, suggesting that not all NE patients suffer from low mucosal perfusion levels.

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.

Effects of Buscopan on human gastrointestinal smooth muscle activity in an ex vivo model: Are there any differences for various sections?

Hyoscine butylbromide (Buscopan ®) is clinically used as an anticholinergic antispasmodic for the treatment of abdominal cramping or visceral pain associated with cramps. However, the spasmolytic efficacy on contractile activity of human gastrointestinal smooth muscle from various sections remains unclear. We aimed to investigate the potentially selective actions of Buscopan on different bowel segments, as well as muscular layers and contractile states. Human smooth muscle tissues of the esophagus, gastric corpus and antrum, jejunum, ileum and colon were obtained. Isometric measurements of circular and longitudinal muscle strips were performed to determine effects of Buscopan on spontaneous activity and induced-contractions by 30mM KCl, 10μM bethanechol and electrical field stimulation (EFS). Buscopan concentration-dependently (10(-9)-10(-5)M) inhibited smooth muscle activity, particularly in spasticity evoked by bethanechol and EFS but not high K(+). The inhibiting effects were mainly responsible for the antagonism on muscarinic M2 and M3 receptors (IC50 values: 3.1×10(-5)M vs. 0.9×10(-5)M). The sensitivity toward Buscopan revealed a tendency of increasing from the esophagus, gastric corpus and antrum to the colon, jejunum and ileum. There was a reversed gradient of mRNA and protein expression of muscarinic M2 and M3 receptors from the blocking effects of Buscopan, which could be ascribed to the fact that a higher concentration of Buscopan was needed to antagonize the spastic contraction to reach the equipotent inhibitory rate in the region with higher muscarinic receptor activity. The findings of different inhibitory effectiveness on various parts of the gastrointestinal tract provide a potential guideline for the clinical application.

Low esophageal mucosal blood flow in patients with nutcracker esophagus

Nutcracker esophagus (NE) is characterized by high-amplitude peristaltic esophageal contractions, and these patients often present with symptoms of "angina-like" or noncardiac chest pain. Tissue ischemia is a known cause of visceral pain, and the goal of our present study was to determine whether esophageal wall blood perfusion (EWBP) is reduced in patients with NE. Fourteen normal subjects (mean age 51 yr, 11 men) and 12 patients (mean age 53 yr, 9 men) with NE and noncardiac chest pain were investigated. The EWBP was measured continuously using a custom-designed laser Doppler probe tethered to a Bravo capsule, which anchored it to the esophageal wall. The baseline EWBP in normal subjects was 651 ± 27 perfusion units. In patients with NE, the baseline EWBP was significantly lower than in the normal subjects (451 ± 32 perfusion units). The EWBP decreased after injection of edrophonium (which increases muscle contractions) and increased following sublingual nitroglycerin administration (which relaxes muscle) in normal subjects, as well as in NE patients. Spontaneous pain events during the recording period were often associated with drops in the EWBP. We propose that low EWBP leads to hypoxia of the esophageal tissue, which may be a mechanism of esophageal pain in patients with NE.

Fundamentals of Neurogastroenterology: Physiology/Motility - Sensation

The fundamental gastrointestinal functions include motility, sensation, absorption, secretion, digestion and intestinal barrier function. Digestion of food and absorption of nutrients normally occurs without conscious perception. Symptoms of functional gastrointestinal disorders are often triggered by meal intake suggesting abnormalities in the physiological processes are involved in the generation of symptoms. In this manuscript, normal physiology and pathophysiology of gastrointestinal function, and the processes underlying symptom generation are critically reviewed. The functions of each anatomical region of the digestive tract are summarized. The pathophysiology of perception, motility, mucosal barrier, and secretion in functional gastrointestinal disorders as well as effects of food, meal intake and microbiota on gastrointestinal motility and sensation are discussed. Genetic mechanisms associated with visceral pain and motor functions in health and functional gastrointestinal disorders are reviewed. Understanding the basis for digestive tract functions is essential to understand dysfunctions in the functional gastrointestinal disorders.

Catheter-based acoustic interrogation device for real-time monitoring of the dynamics of the lower esophageal sphincter: in vitro and pilot canine studies

This paper presents a novel minimally-invasive catheter-based acoustic interrogation device for real-time monitoring the dynamics of the lower esophageal sphincter (LES). Dysfunction of the LES could result gastrointestinal (GI) diseases, such as gastroesophageal reflux disease (GERD). A micro-oscillator actively emitting sound wave at 16 kHz is located at one side of the LES, and a miniature microphone is located at the other side of the LES to capture the sound generated from the oscillator. Thus, the dynamics of the opening and closing of the LES can be monitored. The device was tested in vitro by utilizing a custom-designed LES simulator, as well as in vivo in a pilot canine model. In the in vitro test, the sound was captured by the microphone and its strength was correlated with the level of LES opening and closing which was controlled by the simulator. The measurements showed statistically significant (p  <  0.05) Pearson correlation coefficients (0.905 on the average in quiet environment and 0.736 on the average in noisy environment, DOF  =  9). In the in vivo test, the LES was forced open and closed by a transoral endoscope, which was monitored in real-time by a transpyloric endoscope inserted from the duodenum and positioned into the distal stomach. Frame-by-frame video analysis validated the interrelation between the sound strength and the LES opening and closing. The LES dynamics monitored by the proposed device has the potential to become a valuable minimally-invasive technique for understanding LES dysfunction.

Impaired esophageal motor function in eosinophilic esophagitis

Eosinophilic esophagitis is a chronic immunoallergic inflammatory disease of the esophagus that represents a major cause of digestive morbidity among the pediatric and young adult populations. Despite the fact that key symptoms in adults include dysphagia and food impaction, many patients lack structural changes in the esophagus to account for their complaints, which suggests the presence of underlying motor disorders and esophageal distensibility impairment. In the last few years the esophageal motility of these patients has been studied using various approaches, most particularly high-resolution manometry, ambulatory manometry, and impedance planimetry. This review focuses on the most relevant findings and scientific evidence regarding esophageal motor disorders in eosinophilic esophagitis.

Circular and longitudinal muscles shortening indicates sliding patterns during peristalsis and transient lower esophageal sphincter relaxation

Esophageal axial shortening is caused by longitudinal muscle (LM) contraction, but circular muscle (CM) may also contribute to axial shortening because of its spiral morphology. The goal of our study was to show patterns of contraction of CM and LM layers during peristalsis and transient lower esophageal sphincter (LES) relaxation (TLESR). In rats, esophageal and LES morphology was assessed by histology and immunohistochemistry, and function with the use of piezo-electric crystals and manometry. Electrical stimulation of the vagus nerve was used to induce esophageal contractions. In 18 healthy subjects, manometry and high frequency intraluminal ultrasound imaging during swallow-induced esophageal contractions and TLESR were evaluated. CM and LM thicknesses were measured (40 swallows and 30 TLESRs) as markers of axial shortening, before and at peak contraction, as well as during TLESRs. Animal studies revealed muscular connections between the LM and CM layers of the LES but not in the esophagus. During vagal stimulated esophageal contraction there was relative movement between the LM and CM. Human studies show that LM-to-CM (LM/CM) thickness ratio at baseline was 1. At the peak of swallow-induced contraction LM/CM ratio decreased significantly (<1), whereas the reverse was the case during TLESR (>2). The pattern of contraction of CM and LM suggests sliding of the two muscles. Furthermore, the sliding patterns are in the opposite direction during peristalsis and TLESR.

Non-invasive ultrasound to identify eosinophil granule proteins in eosinophilic esophagitis

Although traditional microbubble contrast agents are bright, the high contrast of gas bubbles and air-water interfaces in the upper gastrointestinal tract renders these agents less useful for diagnosing diseases such as eosinophilic esophagitis, a disease characterized by patchy infiltration of eosinophils into the esophagus. Here we report a first-in-class ultrasound contrast enhancement agent composed of echogenic insulin particles, which are labeled with molecular recognition elements to diagnose eosinophil-associated diseases. We prepared solid echogenic insulin particles, tethered antibodies to eosinophil granule major basic protein 1 (MBP-1) to their surfaces and experimentally evaluated binding of these agents to MBP-1 on ex vivo non-human primate esophagi. We found that insulin particles can be readily observed by ultrasound and bind to MBP-1-coated esophagi within minutes. Our results suggest the potential of this new class of solid contrast agents to image, diagnose and improve management of eosinophilic esophagitis.

Esophageal function testing: beyond manometry and impedance

Manometry and impedance provide only surrogate information regarding longitudinal wall function and are focused on contractile amplitude and lumen content. Ultrasound imaging provides a unique perspective of esophageal function by providing important information regarding longitudinal muscle contraction. Laser Doppler assessment of perfusion may be an important complementary tool to assess abnormal wall blood perfusion as a possible mechanism of pain.

A catheter-based acoustic interrogation device for monitoring motility dynamics of the lower esophageal sphincter

This paper presents novel minimally-invasive, catheter-based acoustic interrogation device for monitoring motility dynamics of the lower esophageal sphincter (LES). A micro-oscillator actively emitting sound wave at 16 kHz is located at one side of the LES, and a miniature microphone is located at the other side of the sphincter to capture the sound generated from the oscillator. Thus, the dynamics of the opening and closing of the LES can be quantitatively assessed. In this paper, experiments are conducted utilizing an LES motility dynamics simulator. The sound strength is captured by the microphone and is correlated to the level of LES opening and closing controlled by the simulator. Measurements from the simulator model show statistically significant (p < 0.05) Pearson correlation coefficients (0.905 on the average in quiet environment and 0.736 on the average in noisy environment, D.O.F. = 9). Measuring the level of LES opening and closing has the potential to become a valuable diagnostic technique for understanding LES dysfunction and the disorders associated with it.

Review of current diagnosis and management of diffuse esophageal spasm, nutcracker esophagus/spastic nutcracker and hypertensive lower esophageal sphincter

PURPOSE OF REVIEW

To cover the diagnosis and management of diffuse esophageal spasm, nutcracker esophagus/spastic nutcracker and hypertensive lower esophageal sphincter. An outline of the presentation and manometric features of these conditions will precede a discussion of therapies. All of these diagnoses are made manometrically, even though they may be suspected by presentation and by findings at video fluoroscopic swallow or gastroscopy testing.

RECENT FINDINGS

The advent of high-resolution manometry testing has allowed a better understanding of these motility disorders, and the ability to standardize the diagnoses by the use of the Chicago Classification is a major step forward. Recent developments show that botulinum toxin and perioral myotomy can be an effective treatment for some patients. This should bring more therapies to the fore in the future, but at present there is still the need for more prospective study of best therapies.

SUMMARY

The important point to remember for all of these conditions is that unlike achalasia, there is no definite pathological correlation to the manometrically observed abnormalities. This therefore makes the management challenging and means that treatment pathways are not as well set out as for some other upper gastrointestinal motility problems.

A critical review of brand and generic alendronate for the treatment of osteoporosis

Objective

Compare in vitro and in vivo characteristics and clinical outcomes of brand and generic alendronate.

Research design and methods: Relevant search terms were input into Medline ("alendronate" AND "generic" up to August 5, 2013) and any abstracts deemed possibly relevant selected for full paper review and abstraction.

Results

Multicentre, randomized, placebo-controlled Phase III clinical trials of substantial size and duration have established the anti-fracture efficacy and safety of brand amino-bisphosphonates. For regulatory approval, generic versions of brand drugs need to demonstrate bioequivalence in young, healthy volunteers and have similar dissolution times. While the potency and amount of active drug within generic formulations must be identical to the brand, differences are permitted in the excipients. Significant differences in tablet disintegration time among different versions of generic and brand alendronate have been reported. Rapidly disintegrating alendronate pills may increase oesophageal bioadhesion and adverse event risk. Oesophageal-bound alendronate or slow disintegrating alendronate tablets may be made inert and ineffective by subsequently ingested food or drink. Investigations have reported a lower persistence to therapy with generic brands of alendronate as compared to brand bisphosphonates and patients switched from brand to generic alendronate have increased adverse event rates and losses in bone mineral density.

Conclusion

Numerous differences exist between brand and generic alendronate including: disintegration time, bioadhesion to the oesophagus, patient persistence to therapy, adverse event incidence, and maintenance of bone mineral density. Generic forms of alendronate warrant closer clinical study before they are ascribed the clinical effectiveness and tolerability of brand alendronate.

Electronic supplementary material

The online version of this article (doi:10.1186/2193-1801-2-550) contains supplementary material, which is available to authorized users.

Longitudinal muscle of the esophagus: its role in esophageal health and disease

PURPOSE OF REVIEW

The muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. The function of the longitudinal muscle and its role in bolus propulsion are not clear. The goal of this review is to summarize what is known of the role of the longitudinal muscle in health, as well as in sensory and motor disorders of the esophagus.

RECENT FINDINGS

Simultaneous manometry and ultrasound imaging reveal that, during peristalsis, the two muscle layers of the esophagus contract in perfect synchrony. On the contrary, during transient lower esophageal sphincter (LES) relaxation, longitudinal muscle contracts independent of the circular muscle. Recent studies have provided novel insights into the role of the longitudinal muscle in LES relaxation and descending relaxation of the esophagus. In certain diseases (e.g. some motility disorders of the esophagus), there is discoordination between the two muscle layers, which likely plays an important role in the genesis of dysphagia and delayed esophageal emptying. There is close temporal correlation between prolonged contractions of the longitudinal muscles of the esophagus and esophageal 'angina-like' pain. Novel techniques to record longitudinal muscle contraction are reviewed.

SUMMARY

Longitudinal muscles of the esophagus play a key role in the physiology and pathophysiology of esophageal sensory and motor function. Neuro-pharmacologic controls of circular and longitudinal muscle are different, which provides an opportunity for the development of novel pharmacological therapies in the treatment of esophageal sensory and motor disorders.

Acid sensitization of esophageal mucosal afferents: implication for symptom perception in patients across the gastroesophageal reflux disease spectrum

BACKGROUND

Sensitization of esophageal chemoreceptors, either directly by intermittent acid exposure or indirectly through esophagitis-associated inflammatory mediators, is likely to be the mechanism underlying the perception of heartburn.

AIMS

To compare basal esophageal sensitivity with electrical stimulation and acid, and to compare the degree of acid-induced sensitization in controls and in patient groups across the entire spectrum of gastroesophageal reflux disease: erosive oesophagitis (EO), nonerosive reflux disease (NERD), and functional heartburn (FH).

METHODS

Esophageal sensory and pain thresholds to electrical stimulation were measured before, 30, and 60 minutes after an intraesophageal infusion of saline or HCl. Patients received a 30-minute infusion of 0.15 M HCl and controls were randomized to receive either HCl (n = 11) or saline (n = 10). After electrical sensory threshold testing, participants received another 30-minute infusion of HCl to determine whether sensitivity to acid is increased by prior acid exposure

RESULTS

All patient groups had higher basal sensory thresholds than healthy controls (controls, 13 ± 1.4 mA; FH, 20 ± 5.1 mA; NERD, 21 ± 5.1 mA; EO, 23 ± 5.4 mA; P < 0.05). Acute esophageal acid exposure reduced sensory thresholds to electrical stimulation in FH and NERD patients (P < 0.05). The level of acid sensitivity during the first HCl infusion was comparable between all patient groups and controls. The secondary infusion caused increased discomfort in all participants (P < 0.01). This acid-induced sensitization to HCl was significantly elevated in the patient groups ( P < 0.05).

CONCLUSIONS

(1) Esophageal acid infusion sensitizes it to subsequent electrical and chemical stimulation. (2) The acid-related sensitization is greater in gastroesophageal reflux disease than in controls and may influence in part symptom perception in this population. (3) Acid-related sensitization within the gastroesophageal reflux disease population is not dependant on mucosal inflammation.

Longitudinal muscle dysfunction in achalasia esophagus and its relevance

Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the lower esophageal sphincter (LES), longitudinal muscle contracts independently of circular muscle. Recent studies provide novel insights, i.e., longitudinal muscle contraction of the esophagus induces LES relaxation and possibly descending relaxation of the esophagus. In achalasia esophagus and other motility disorders there is discoordination between the 2 muscle layers. Longitudinal muscle contraction patterns are different in the recently described three types of achalasia identified by high-resolution manometry. Robust contraction of the longitudinal muscle in type II achalasia causes pan-esophageal pressurization and is the mechanism of whatever little esophageal emptying that take place in the absence of peristalsis and impaired LES relaxation. It may be that preserved longitudinal muscle contraction is also the reason for superior outcome to medical/surgical therapy in type II achalasia esophagus. Prolonged contractions of longitudinal muscles of the esophagus is a possible mechanism of heartburn and "angina like" pain seen in esophageal motility disorders and possibly achalasia esophagus. Novel techniques to record longitudinal muscle contraction are on the horizon. Neuro-pharmacologic control of circular and longitudinal muscles is different, which provides an important opportunity for the development of novel pharmacological therapies to treat sensory and motor disorders of the esophagus.

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

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

Characteristics of esophageal proper muscle in patients with non-cardiac chest pain using high-frequency intraluminal ultrasound

BACKGROUND AND AIM

It is unclear which mechanisms play a predominant role in the pathogenesis of esophageal non-cardiac chest pain (NCCP). We aimed to examine the features of esophageal proper muscle and esophageal contractility using a high-frequency intraluminal ultrasound (HFIUS) in patients with NCCP.

METHODS

A total of 68 patients with NCCP were classified into two groups according to the results of typical reflux symptoms and/or esophagogastroduodenoscopy and/or 24-h esophageal pH monitoring: gastroesophageal reflux disease (GERD)-positive NCCP (n = 34) and GERD-negative NCCP groups (n = 34). Additionally 16 asymptomatic healthy subjects were included as controls. Using HFIUS, we analyzed the esophageal proper muscle thickness and cross-sectional area (CSA) at 3 cm above lower esophageal sphincter (LES) and 9 cm above LES during baseline rest and peak contraction periods among the control, GERD-positive NCCP and GERD-negative NCCP groups, and examined the completeness of three phases of esophageal action during five wet swallows in the three groups.

RESULTS

The muscle thickness and CSA tended to be larger in GERD-negative NCCP than in GERD-positive NCCP and in control groups at esophageal body during both periods. All of the controls and patients with GERD-positive NCCP presented the complete peristaltic type. Whereas, 11 of 34 patients with GERD-negative NCCP presented the incomplete peristaltic type.

CONCLUSIONS

Using HFIUS, patients with GERD-negative NCCP had increased muscle thickness and CSA. Some GERD-negative NCCP had the incomplete peristaltic type.

High-resolution Manometry: Esophageal Disorders Not Addressed by the "Chicago Classification"

The development of the high-resolution esophageal manometry (HRM) and the Chicago classification have improved the diagnosis and management of esophageal motility disorders. However, some conditions have yet to be addressed by this classification. This review describes findings in HRM which are not included in the current Chicago classification based on the experience in our center. This includes the analysis of the upper esophageal sphincter, proximal esophagus, longitudinal muscle contraction, disorders related to gastroesophageal reflux disease and respiratory symptoms. The utility of provocative tests and the use of HRM in the evaluation of rumination syndrome and post-surgical patients will also be discussed. We believe that characterization of the manometric findings in these areas will eventually lead to incorporation of new criteria into the existing classification.

Esophageal wall blood perfusion during contraction and transient lower esophageal sphincter relaxation in humans

We recently reported that esophageal contraction reduces esophageal wall perfusion in an animal study. Our aim was to determine esophageal wall blood perfusion (EWBP) during esophageal contraction and transient lower esophageal sphincter relaxations (TLESRs) in humans. We studied 12 healthy volunteers. A custom-designed laser Doppler probe was anchored to the esophageal wall, 4-6 cm above the LES, by use of the Bravo pH system so that the laser light beam stay directed toward the esophageal mucosa. A high-resolution manometry equipped with impedance electrodes recorded esophageal pressures and reflux events. Synchronized pressure, impedance, pH, and EWBP recordings were obtained during dry and wet swallows and following a meal. Stable recordings of laser Doppler EWBP were only recorded when the laser Doppler probe was firmly anchored to the esophageal wall. Esophageal contractions induced by dry and wet swallows resulted in 46 ± 9% and 60 ± 10% reduction in the EWBP, respectively (compared to baseline). Reduction in EWBP was directly related to the amplitude (curvilinear fit) and duration of esophageal contraction. Atropine reduced the esophageal contraction amplitude and decreased the EWBP reduction associated with esophageal contraction. TLESRs were also associated with reduction in the EWBP, albeit of smaller amplitude (29 ± 3%) but longer duration (19 ± 2 s) compared with swallow-induced esophageal contractions. We report 1) an innovative technique to record EWBP for extended time periods in humans and 2) contraction of circular and longitudinal muscle during peristalsis and selective longitudinal muscle contraction during TLESR causes reduction in the EWBP; 3) using our innovative technique, future studies may determine whether esophageal wall ischemia is the cause of esophageal pain/heartburn.

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.

Red chlorophyll: the new barium?

Imaging of gastrointestinal (GI) motility remotely through the abdominal wall has always been a tradeoff between resolution and invasiveness. Skin reflects and/or absorbs wavelengths of radiation in the ultraviolet and visible ranges, but is largely transparent to both high-energy radiation (Gamma to X-rays; <0.1-10 nm) and low-energy radiation (infrared to radio waves; 700 nm-10 m). Imaging using short wavelength radiation such as X-ray cinematography has excellent spatial and temporal resolution, but ionization can produce acute and long-term deleterious effects to the patient or animal. Other 'slice-based' imaging techniques such as ultrasound/MRI/CT minimize tissue damage, but are limited in the planar area that can be imaged in a timely fashion. This viewpoint article will summarize and explore the implications of recent advances in infrared imaging of the GI tract, in particular, an article published in this issue of NGM entitled 'In vivo dynamic imaging of intestinal motions using diet-related autofluorescence' in which the authors have used infrared imaging in combination with that most elusive ingredient, standard mouse chow, to capture the motions of the mouse GI tract.

Current and future techniques in the evaluation of dysphagia

Dysphagia is common in the general population, and is generally due to either mechanical obstruction or dysmotility. Patient demographics and symptom evaluation are often useful in determining the likely cause, and guide subsequent investigation and management. Oropharyngeal dysphagia is usually caused by neurological conditions where treatment options are limited. Conversely, many of the esophageal causes of dysphagia are amenable to therapy. Gastroscopy is often the first test of choice, given its diagnostic and therapeutic potential, especially when mechanical causes are concerned. Esophageal motor function can be assessed by a variety of techniques, ranging from radiology such as barium swallow, to dedicated motility tests such as manometry and impedance monitoring. The choice of test relies on the clinical indication and the results should be interpreted in conjunction with the patients' symptoms. High-resolution manometry with topography is now the new benchmark for motility studies. Several new techniques for motility testing have also become available, such as esophageal ultrasound and functional lumen imaging probe, but are currently limited to the research setting.

Intraluminal ultrasonic probe for volumetric monitoring of liquid gastroesophageal reflux

Methods for volumetric monitoring of liquid gastroesophageal reflux (GER) are still lacking. The aim of this study was to develop an automated intraluminal measurement technique which allows ambulatory volumetric quantification of liquid GER utilizing a minimum-cost intraluminal ultrasonic probe. This probe consists of two 2 MHz ultrasonic crystals longitudinally assembled along a multi-channel intraluminal impedance (MII) catheter. The proposed probe was initially tested with tubular phantoms of different diameters. Measurements of the cross-sectional areas of the phantoms showed high correlation with the actual areas (R(2) = 0.99). Subsequently, two in-vivo human tests were performed. For each human test the catheter assembly was inserted transnasally and the ultrasonic probe was placed in the area of the lower esophageal sphincter. Multiple liquid swallows of different volumes were invoked using electrolyte drinks. Sectional luminal volume (SLV) in the esophagus between the two ultrasonic crystals was obtained. Results of the swallows demonstrated that measured SLVs correlated with the actual swallowed liquid volume. The ultrasonic probe was combined with a MII catheter to discriminate between antegrade and retrograde bolus transit. Increases of SLVs during liquid GER episodes could be utilized to evaluate GER volume in the vicinity of the ultrasonic probe.

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

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

Ambulatory high-resolution manometry, lower esophageal sphincter lift and transient lower esophageal sphincter relaxation

BACKGROUND

Lower esophageal sphincter (LES) lift seen on high-resolution manometry (HRM) is a possible surrogate marker of the longitudinal muscle contraction of the esophagus. Recent studies suggest that longitudinal muscle contraction of the esophagus induces LES relaxation.

AIM

Our goal was to determine: (i) the feasibility of prolonged ambulatory HRM and (ii) to detect LES lift with LES relaxation using ambulatory HRM color isobaric contour plots.

METHODS

In vitro validation studies were performed to determine the accuracy of HRM technique in detecting axial movement of the LES. Eight healthy normal volunteers were studied using a custom designed HRM catheter and a 16 channel data recorder, in the ambulatory setting of subject's home environment. Color HRM plots were analyzed to determine the LES lift during swallow-induced LES relaxation as well as during complete and incomplete transient LES relaxations (TLESR).

KEY RESULTS

Satisfactory recordings were obtained for 16 h in all subjects. LES lift was small (2 mm) in association with swallow-induced LES relaxation. LES lift could not be measured during complete TLESR as the LES is not identified on the HRM color isobaric contour plot once it is fully relaxed. On the other hand, LES lift, mean 8.4 ± 0.6 mm, range: 4-18 mm was seen with incomplete TLESRs (n = 80).

CONCLUSIONS & INFERENCES

Our study demonstrates the feasibility of prolonged ambulatory HRM recordings. Similar to a complete TLESR, longitudinal muscle contraction of the distal esophagus occurs during incomplete TLESRs, which can be detected by the HRM. Using prolonged ambulatory HRM, future studies may investigate the temporal correlation between abnormal longitudinal muscle contraction and esophageal symptoms.

High resolution manometry patterns distinguish acid sensitivity in non-cardiac chest pain

BACKGROUND

High resolution manometry (HRM) has demonstrated two distinct smooth muscle contraction segments in the esophageal body; changes in these segments typify certain esophageal disorders. We investigated segmental characteristics in subgroups of non-cardiac chest pain (NCCP).

METHODS

32 NCCP subjects were segregated into a GERD group (ambulatory pH testing off antisecretory therapy showing elevated total acid exposure time, AET≥4.0% and positive symptom association probability, SAP) and an acid sensitive group (normal AET and positive SAP). HRM Clouse plots were analyzed; smooth muscle segment lengths, pressure amplitude peaks were measured for segment 2 and segment 3 (proximal and distal smooth muscle segments). Pressure volumes were determined in mmHg cm(-1) s(-1) for each peristaltic segment, and ratios of segment 3:segment 2 calculated. Values were compared to a cohort of 14 normal controls.

KEY RESULTS

A distinctive shift in peak contraction amplitude to segment 3 was evident in the acid sensitive group (segment 2, 100.03±11.06mmHg, segment 3, 145.23± 10.29mmHg, P=0.006). Pressure volumes were similarly shifted to segment 3 (segment 2: 855.3 ± 135.1 mmHg cm(-1)  s(-1) , segment 3: 2115.2±218.6 mmHg cm(-1) s(-1) , P<0.005). In contrast, peak amplitude and pressure volume were near equal in the two segments in GERD and control groups. A threshold segment 3:segment 2 pressure volume ratio of 1.9 had the best performance characteristic for segregating acid sensitivity subjects from all GERD and control subjects.

CONCLUSIONS & INFERENCES

Shift in contractile vigor to the third peristaltic segment may be seen in acid sensitive subjects. HRM characteristics of smooth muscle contraction segments are of value in making this determination.