Investigation of esophageal sensation and biomechanical properties in functional chest pain

Capsaicin-Sensitive Vagal Afferent Nerve-Mediated Interoceptive Signals in the Esophagus

Heartburn and non-cardiac chest pain are the predominant symptoms in many esophageal disorders, such as gastroesophageal reflux disease (GERD), non-erosive reflux disease (NERD), functional heartburn and chest pain, and eosinophilic esophagitis (EoE). At present, neuronal mechanisms underlying the process of interoceptive signals in the esophagus are still less clear. Noxious stimuli can activate a subpopulation of primary afferent neurons at their nerve terminals in the esophagus. The evoked action potentials are transmitted through both the spinal and vagal pathways to their central terminals, which synapse with the neurons in the central nervous system to induce esophageal nociception. Over the last few decades, progress has been made in our understanding on the peripheral and central neuronal mechanisms of esophageal nociception. In this review, we focus on the roles of capsaicin-sensitive vagal primary afferent nodose and jugular C-fiber neurons in processing nociceptive signals in the esophagus. We briefly compare their distinctive phenotypic features and functional responses to mechanical and chemical stimulations in the esophagus. Then, we summarize activation and/or sensitization effects of acid, inflammatory cells (eosinophils and mast cells), and mediators (ATP, 5-HT, bradykinin, adenosine, S1P) on these two nociceptive C-fiber subtypes. Lastly, we discuss the potential roles of capsaicin-sensitive esophageal afferent nerves in processing esophageal sensation and nociception. A better knowledge of the mechanism of nociceptive signal processes in primary afferent nerves in the esophagus will help to develop novel treatment approaches to relieve esophageal nociceptive symptoms, especially those that are refractory to proton pump inhibitors.

Diagnosis and Management of Functional Chest Pain in the Rome IV Era

Functional chest pain accounts for about a third of the patients with noncardiac chest pain. It is a very common functional esophageal disorder that remains even today a management challenge to the practicing physician. Based on the definition offered by the Rome IV criteria, diagnosis of functional chest pain requires a negative workup of noncardiac chest pain patients that includes, proton pump inhibitor test or empirical proton pump inhibitor trial, endoscopy with esophageal mucosal biopsies, reflux testing, and esophageal manometry. The mainstay of treatment are neuromodulators that are primarily composed of anti-depressants. Alternative medicine and psychological interventions may be provided alone or in combination with other therapeutic modalities.

The role of oesophageal physiological testing in the assessment of noncardiac chest pain

Oesophageal physiology testing plays an important role in the diagnosis of noncardiac chest pain (NCCP) after cardiac, structural and mucosal abnormalities have been ruled out. Endoscopy can establish the presence of structural causes of chest pain such as cancer, oesophageal webs and diverticula. Even if macroscopically normal, eosinophilic oesophagitis is a common cause of chest pain and needs to be ruled out with an adequate biopsy regimen. In the remaining cases, diagnosis is focused on the identification of often subtle mechanisms that lead to NCCP. The most common oesophageal aetiologies for NCCP are gastro-oesophageal reflux disease (GORD), oesophageal dysmotility and functional chest pain. Ambulatory pH studies (with or without impedance or wireless measurements) can establish the presence of GORD, nonerosive reflux as well any association with symptoms of chest pain. High-resolution manometry, particularly with the inclusion of adjunctive testing, can rule out major motility disorders such as spasm, hypercontraction or achalasia. The EndoFLIP device can help define disorders with reduced distensibility, not easily appreciated with endoscopy or manometry. When all tests remain negative, a diagnosis of oesophageal hypersensitivity is normally made and therapy is shifted from targeting a disease to treating symptoms and patient affect.

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.

Functional lumen imaging probe: The FLIP side of esophageal disease

PURPOSE OF REVIEW

The aim of this review is to summarize use of the functional lumen imaging probe (FLIP) for the evaluation and management of esophageal diseases.

RECENT FINDINGS

The FLIP utilizes high-resolution impedance planimetry to evaluate the functional geometry and cross-sectional area/pressure relationship (i.e. distensibility) of the esophageal sphincters and body. Recent studies have reported the potential utility of FLIP to evaluate esophageal diseases, such as achalasia, gastroesophageal reflux disease, and eosinophilic esophagitis.

SUMMARY

Esophageal distensibility measures provided by the FLIP will add to our understanding of the contribution of esophageal mechanical properties to esophageal symptoms and function. Application of the FLIP in clinical practice complements the diagnostic evaluation of esophageal function and may also be a valuable tool to help direct and target clinical management of esophageal diseases.

Feasibility and acceptability of esophageal-directed hypnotherapy for functional heartburn

Functional heartburn (FH) is a benign but burdensome condition characterized by painful, burning epigastric sensations in the absence of acid reflux or symptom-reflux correlation. Esophageal hypersensitivity and its psychological counterpart, esophageal hypervigilance (EHv) drive symptom experience. Hypnotherapy (HYP) is an established and preferred intervention for refractory symptoms in functional gastrointestinal disorders (FGIDs) and could be applied to FH. The objective of this study was to determine the feasibility, acceptability, and clinical utility of 7 weekly sessions of esophageal-directed HYP (EHYP) on heartburn symptoms, quality of life, and EHv. Similar to other work in FGIDs and regardless of hypnotizability, there were consistent and significant changes in heartburn symptoms, visceral anxiety, and quality of life and a trend for improvement in catastrophizing. We would recommend EHYP in FH patients who are either non-responsive to medications or who would prefer a lifestyle intervention.

Mechanisms of the adenosine A2A receptor-induced sensitization of esophageal C fibers

Clinical studies indicate that adenosine contributes to esophageal mechanical hypersensitivity in some patients with pain originating in the esophagus. We have previously reported that the esophageal vagal nodose C fibers express the adenosine A2A receptor. Here we addressed the hypothesis that stimulation of the adenosine A2A receptor induces mechanical sensitization of esophageal C fibers by a mechanism involving transient receptor potential A1 (TRPA1). Extracellular single fiber recordings of activity originating in C-fiber terminals were made in the ex vivo vagally innervated guinea pig esophagus. The adenosine A2A receptor-selective agonist CGS21680 induced robust, reversible sensitization of the response to esophageal distention (10-60 mmHg) in a concentration-dependent fashion (1-100 nM). At the half-maximally effective concentration (EC50: ≈3 nM), CGS21680 induced an approximately twofold increase in the mechanical response without causing an overt activation. This sensitization was abolished by the selective A2A antagonist SCH58261. The adenylyl cyclase activator forskolin mimicked while the nonselective protein kinase inhibitor H89 inhibited mechanical sensitization by CGS21680. CGS21680 did not enhance the response to the purinergic P2X receptor agonist α,β-methylene-ATP, indicating that CGS21680 does not nonspecifically sensitize to all stimuli. Mechanical sensitization by CGS21680 was abolished by pretreatment with two structurally different TRPA1 antagonists AP18 and HC030031. Single cell RT-PCR and whole cell patch-clamp studies in isolated esophagus-specific nodose neurons revealed the expression of TRPA1 in A2A-positive C-fiber neurons and demonstrated that CGS21682 potentiated TRPA1 currents evoked by allylisothiocyanate. We conclude that stimulation of the adenosine A2A receptor induces mechanical sensitization of nodose C fibers by a mechanism sensitive to TRPA1 antagonists indicating the involvement of TRPA1.

Hypnotherapy for Esophageal Disorders

Hypnotherapy is an evidence based intervention for the treatment of functional bowel disorders, particularly irritable bowel syndrome. While similar in pathophysiology, less is known about the utility of hypnotherapy in the upper gastrointestinal tract. Esophageal disorders, most of which are functional in nature, cause painful and uncomfortable symptoms that impact patient quality of life and are difficult to treat from a medical perspective. After a thorough medical workup and a failed trial of proton pump inhibitor therapy, options for treatment are significantly limited. While the pathophysiology is likely multifactorial, two critical factors are believed to drive esophageal symptoms--visceral hypersensitivity and symptom hypervigilance. The goal of esophageal directed hypnotherapy is to promote a deep state of relaxation with focused attention allowing the patient to learn to modulate physiological sensations and symptoms that are not easily addressed with conventional medical intervention. Currently, the use of hypnosis is suitable for dysphagia, globus, functional chest pain/non-cardiac chest pain, dyspepsia, and functional heartburn. In this article the authors will provide a rationale for the use of hypnosis in these disorders, presenting the science whenever available, describing their approach with these patients, and sharing a case study representing a successful outcome.

Gastroesophageal reflux symptoms not responding to proton pump inhibitor: GERD, NERD, NARD, esophageal hypersensitivity or dyspepsia?

Gastroesophageal reflux (GER) is a common gastrointestinal process that can generate symptoms of heartburn and chest pain. Proton pump inhibitors (PPIs) are the gold standard for the treatment of GER; however, a substantial group of GER patients fail to respond to PPIs. In the past, it was believed that acid reflux into the esophagus causes all, or at least the majority, of symptoms attributed to GER, with both erosive esophagitis and nonerosive outcomes. However, with modern testing techniques it has been shown that, in addition to acid reflux, the reflux of nonacid gastric and duodenal contents into the esophagus may also induce GER symptoms. It remains unknown how weakly acidic or alkaline refluxate with a pH similar to a normal diet induces GER symptoms. Esophageal hypersensitivity or functional dyspepsia with superimposed heartburn may be other mechanisms of symptom generation, often completely unrelated to GER. Detailed studies investigating the pathophysiology of esophageal hypersensitivity are not conclusive, and definitions of the various disease states may overlap and are often confusing. The authors aim to clarify the pathophysiology, definition, diagnostic techniques and medical treatment of patients with heartburn symptoms who fail PPI therapy.

Lack of correlation between HRM metrics and symptoms during the manometric protocol

OBJECTIVES

Although esophageal motor disorders are associated with chest pain and dysphagia, minimal data support a direct relationship between abnormal motor function and symptoms. This study investigated whether high-resolution manometry (HRM) metrics correlate with symptoms.

METHODS

Consecutive HRM patients without previous surgery were enrolled. HRM studies included 10 supine liquid, 5 upright liquid, 2 upright viscous, and 2 upright solid swallows. All patients evaluated their esophageal symptom for each upright swallow. Symptoms were graded on a 4-point likert score (0, none; 1, mild; 2, moderate; 3, severe). The individual liquid, viscous or solid upright swallow with the maximal symptom score was selected for analysis in each patient. HRM metrics were compared between groups with and without symptoms during the upright liquid protocol and the provocative protocols separately.

RESULTS

A total of 269 patients recorded symptoms during the upright liquid swallows and 72 patients had a swallow symptom score of 1 or greater. Of the 269 patients, 116 recorded symptoms during viscous or solid swallows. HRM metrics were similar between swallows with and without associated symptoms in the upright, viscous, and solid swallows. No correlation was noted between HRM metrics and symptom scores among swallow types.

CONCLUSIONS

Esophageal symptoms are not related to abnormal motor function defined by HRM during liquid, viscous or solid bolus swallows in the upright position. Other factors beyond circular muscle contraction patterns should be explored as possible causes of symptom generation.

Advances in motility testing--current and novel approaches

Disorders of gastrointestinal motility are frequently seen in clinical practice. Apart from motility disorders, factors leading to lowered visceroperception thresholds are recognized as commonly involved in the pathogenesis of functional gastrointestinal disorders. The wide array of gastrointestinal motility and viscerosensitivity tests available is in contrast with the relatively limited number of tests used universally in clinical practice. The main reason for this discrepancy is that the outcome of a test only becomes truly important when it carries clinical consequences. The main goal of this Review is to assess the place of the presently available gastrointestinal motility and sensitivity tests in the clinical armamentarium of the gastroenterologist.

Diagnostic utility of the oesophageal balloon distension test in the evaluation of oesophageal chest pain

BACKGROUND

Oesophageal balloon distension test (EBDT) has been advocated for the evaluation of functional oesophageal noncardiac chest pain (NCCP), but its diagnostic utility remains unclear.

AIM

To prospectively assess the diagnostic yield of EBDT in clinical practice and compare its yield with standard oesophageal tests.

METHODS

Over a period of 6 years, patients with chest pain and negative cardiac work-up underwent sequential testing with endoscopy/biopsy, oesophageal manometry, 24 h pH study and EBDT to elucidate an oesophageal source for their symptoms. Patients with a definite abnormality, for example, erosive oesophagitis on oesophagogastroduodenoscopy (EGD) were designated as having positive test and excluded from further work up.

RESULTS

Of 348 (m/f = 105/243) suspected NCCP patients, 16 (5%) were excluded; 332 (95%) underwent oesophageal testing. Among these, 48 (14%) had macro/microscopic oesophagitis on endoscopy, 7 (2%) had achalasia and 96 (28%) had excessive acid reflux (pH study). The remaining 181 (52%) patients underwent EBDT; 128 (37%) had oesophageal hypersensitivity. Chest pain was reproduced in 97/128 (75%) subjects. There were no adverse effects.

CONCLUSIONS

Oesophageal testing can reveal an oesophageal source for chest pain in 86% of NCCP subjects. The majority (42%) of patients had gastro-oesophageal reflux disease (GERD). Oesophageal balloon distension test identified hypersensitivity in over one-third of subjects. The oesophageal balloon distension test provides useful diagnostic information and should be performed routinely in patients with NCCP after excluding GERD.

Barostat or dynamic balloon distention test: which technique is best suited for esophageal sensory testing?

Esophageal sensation is commonly assessed by barostat-assisted balloon distension (BBD) or dynamic balloon distension (DBD) technique, but their relative merits are unknown. Our aim was to compare the usefulness and tolerability of both techniques. Sixteen healthy volunteers (male/female = 6/10) randomly underwent graded esophageal balloon distensions, using either BBD (n= 8) or DBD (n= 8). BBD was performed by placing a 5-cm long highly compliant balloon attached to a barostat, and DBD by placing a 5-cm long balloon attached to a leveling container. Intermittent phasic balloon distensions were performed in increments of 6 mm Hg. Sensory thresholds and biomechanical properties were assessed and compared. Sensory thresholds for first perception (mean ± standard deviation; 21 ± 6 vs. 21.2 ± 5, mm Hg, P= 0.9), discomfort (38 ± 8 vs. 35 ± 9, P= 0.5), and pain (44 ± 4 vs. 45 ± 3, P= 0.7) were similar with BBD and DBD techniques. However, more subjects tolerated DBD (7/8, 88%) when compared with BBD (4/8, 50%). Forceful expulsion of balloon into stomach (n= 4), pulling around the mouth (n= 4), chest discomfort (n= 2) and retching (n= 2) were overlapping reasons for intolerance with BBD. Esophageal wall distensibility was similar with both techniques. Both techniques provided comparable data on biomechanical properties. However, DBD was better tolerated than BBD for evaluation of esophageal sensation. Hence, we recommend DBD for performing esophageal balloon distension test.

Noncardiac chest pain: epidemiology, natural course and pathogenesis

Noncardiac chest pain is defined as recurrent chest pain that is indistinguishable from ischemic heart pain after a reasonable workup has excluded a cardiac cause. Noncardiac chest pain is a prevalent disorder resulting in high healthcare utilization and significant work absenteeism. However, despite its chronic nature, noncardiac chest pain has no impact on patients' mortality. The main underlying mechanisms include gastroesophageal reflux, esophageal dysmotility and esophageal hypersensitivity. Gastroesophageal reflux disease is likely the most common cause of noncardiac chest pain. Esophageal dysmotility affects only the minority of noncardiac chest pain patients. Esophageal hypersensitivity may be present in non-GERD-related noncardiac chest pain patients regardless if esophageal dysmotility is present or absent. Psychological co-morbidities such as panic disorder, anxiety, and depression are also common in noncardiac chest pain patients and often modulate patients' perception of disease severity.

Adenosine-induced activation of esophageal nociceptors

Clinical studies implicate adenosine acting on esophageal nociceptive pathways in the pathogenesis of noncardiac chest pain originating from the esophagus. However, the effect of adenosine on esophageal afferent nerve subtypes is incompletely understood. We addressed the hypothesis that adenosine selectively activates esophageal nociceptors. Whole cell perforated patch-clamp recordings and single-cell RT-PCR analysis were performed on the primary afferent neurons retrogradely labeled from the esophagus in the guinea pig. Extracellular recordings were made from the isolated innervated esophagus. In patch-clamp studies, adenosine evoked activation (inward current) in a majority of putative nociceptive (capsaicin-sensitive) vagal nodose, vagal jugular, and spinal dorsal root ganglia (DRG) neurons innervating the esophagus. Single-cell RT-PCR analysis indicated that the majority of the putative nociceptive (transient receptor potential V1-positive) neurons innervating the esophagus express the adenosine receptors. The neural crest-derived (spinal DRG and vagal jugular) esophageal nociceptors expressed predominantly the adenosine A(1) receptor while the placodes-derived vagal nodose nociceptors expressed the adenosine A(1) and/or A(2A) receptors. Consistent with the studies in the cell bodies, adenosine evoked activation (overt action potential discharge) in esophageal nociceptive nerve terminals. Furthermore, the neural crest-derived jugular nociceptors were activated by the selective A(1) receptor agonist CCPA, and the placodes-derived nodose nociceptors were activated by CCPA and/or the selective adenosine A(2A) receptor CGS-21680. In contrast to esophageal nociceptors, adenosine failed to stimulate the vagal esophageal low-threshold (tension) mechanosensors. We conclude that adenosine selectively activates esophageal nociceptors. Our data indicate that the esophageal neural crest-derived nociceptors can be activated via the adenosine A(1) receptor while the placodes-derived esophageal nociceptors can be activated via A(1) and/or A(2A) receptors. Direct activation of esophageal nociceptors via adenosine receptors may contribute to the symptoms in esophageal diseases.

The hypersensitive esophagus: pathophysiology, evaluation, and treatment options

Visceral hypersensitivity plays a key role in the pathogenesis of esophageal functional disorders such as functional heartburn and chest pain of presumed esophageal origin (noncardiac chest pain). About 80% of patients with unexplained noncardiac chest pain exhibit lower esophageal sensory thresholds when compared to controls during esophageal sensory testing (ie, esophageal barostat, impedance planimetry). Such information has led to prescription of peripherally and/or centrally acting therapies for the management of these patients. This review summarizes and highlights recent and significant findings regarding the pathophysiology, evaluation, and treatment of the hypersensitive esophagus, a central factor in functional esophageal disorders.

Exertional esophageal pH-metry and manometry in recurrent chest pain

AIM: To investigate the diagnostic efficacy of 24-h and exertional esophageal pH-metry and manometry in patients with recurrent chest pain.

METHODS: The study included 111 patients (54% male) with recurrent angina-like chest pain, non-responsive to therapy with proton pump inhibitors. Sixty-five (59%) had non-obstructive lesions in coronary artery angiography, and in 46 (41%) significant coronary artery narrowing was found. In all patients, 24-h esophageal pH-metry and manometry, and treadmill stress tests with simultaneous esophageal pH-metry and manometry monitoring were performed. During a 24-h examination the percentage of spontaneous chest pain (sCP) episodes associated with acid reflux or dysmotility (symptom index, SI) was calculated. Patients with SI > 50% for acid gastroesophageal reflux (GER) were classified as having GER-related sCP. The remaining symptomatic individuals were determined as having non-GER-related sCP. During the stress test, the occurrence of chest pain, episodes of esophageal acidification (pH < 4 for 10 s) and esophageal spasm with more than 55% of simultaneous contractions (exercise-provoked esophageal spasm or EPES) were noted.

RESULTS: Sixty-eight (61%) individuals reported sCP during 24-h esophageal function monitoring. Eleven of these (16%) were classified as having GER-related sCP and 53/68 (84%) as having non-GER-related sCP. The exercise-provoked chest pain during a stress test occurred in 13/111 (12%) subjects. In order to compare the clinical usefulness of 24-h esophageal function monitoring and its examination limited only to the treadmill stress test, the standard parameters of diagnostic test evaluation were determined. The occurrence of GER-related or non-GER-related sCP was assumed as a “gold standard”. Afterwards, accuracy, sensitivity and specificity were calculated. These parameters expressed a prediction of GER-related or non-GER-related sCP occurrence by the presence of chest pain, esophageal acidification and EPES. Accuracy, sensitivity and specificity of chest pain during the stress test predicting any sCP occurrence were 28%, 35% and 80%, respectively, predicting GER-related sCP were 42%, 0% and 83%, respectively, and predicting non-GER-related sCP were 57%, 36% and 83%, respectively. Similar values were obtained for exercise-related acidification with pH < 4 longer than 10 s in the prediction of GER-related sCP (44%, 36% and 92%, respectively) and EPES in relation to non-GER-related sCP (48%, 23% and 84%, respectively).

CONCLUSION: The presence of chest pain, esophageal acidification and EPES had greater than 80% specificity to exclude the GER-related and non-GER-related causes of recurrent chest pain.