The Severity of Reduced Esophageal Distensibility Parallels Eosinophilic Esophagitis Disease Duration.

BACKGROUND & AIMS: Chronic inflammation of eosinophilic esophagitis (EoE) results in progressive, fibrostenotic remodeling of the esophageal wall. This study aimed to demonstrate objective changes in esophageal distensibility relative to duration of EoE disease using a functional lumen imaging probe (FLIP). METHODS: Adult patients with EoE who completed a 16-cm FLIP protocol during endoscopy were evaluated in a cross-sectional study. FLIP analysis focused on distensibility plateau (DP) of the esophageal body. The time from onset of symptoms to time of endoscopy with FLIP was assessed, as was time from symptom onset to EoE diagnosis (ie, diagnostic delay). RESULTS: A total of 171 patients (mean age 38 ± 12 years; 31% female) were included; the median symptom duration was 8 (interquartile range, 3-15) years and diagnostic delay was 4 (interquartile range, 1-12) years. At the time of endoscopy with FLIP, there were 54 patients (39%) in histologic remission (<15 eosinophils per high-power field [eos/hpf]). Symptom duration and diagnostic delay were negatively correlated with DP (rho = -0.326 and -0.309; P values < .001). Abnormal esophageal distensibility (DP ≤17 mm) was more prevalent with increased duration of symptoms (P < .004): 23% at <5 years to 64% at ≥25 years. When stratifying the cohort based on mucosal eosinophil density, patients with ≥15 eos/hpf had significantly lower DP with greater symptom duration (P = .004), while there was not a significant difference among patients with <15 eos/hpf (P = .060). CONCLUSIONS: Esophageal distensibility objectively measured with FLIP was reduced in EoE patients with greater symptom duration and diagnostic delay. This supports that EoE is a progressive, fibrostenotic disease and that FLIP may be a useful tool to monitor disease progression in EoE.

A Mechanics-Based Perspective on the Function of Human Sphincters During Functional Luminal Imaging Probe Manometry.

Functional luminal imaging probe (FLIP) is used to measure cross-sectional area (CSA) and pressure at sphincters. It consists of a catheter surrounded by a fluid filled cylindrical bag, closed on both ends. Plotting the pressure-CSA hysteresis of a sphincter during a contraction cycle, which is available through FLIP testing, offers information on its functionality, and can provide diagnostic insights. However, limited work has been done to explain the mechanics of these pressure-CSA loops. This work presents a consolidated picture of pressure-CSA loops of different sphincters. Clinical data reveal that although sphincters have a similar purpose (controlling the flow of liquids and solids by opening and closing), two different pressure-CSA loop patterns emerge: negative slope loop (NSL) and positive slope loop (PSL). We show that the loop type is the result of an interplay between (or lack thereof) two mechanical modes: (i) neurogenic mediated relaxation of the sphincter muscle or pulling applied by external forces, and (ii) muscle contraction proximal to the sphincter which causes mechanical distention. We conclude that sphincters which only function through mechanism (i) exhibition NSL whereas sphincters which open as a result of both (i) and (ii) display a PSL. This work provides a fundamental mechanical understanding of human sphincters. This can be used to identify normal and abnormal phenotypes for the different sphincters and help in creating physiomarkers based on work calculation.

An Investigation of the Energy Harvesting Capabilities of a Novel Three-Dimensional Super-Cell Phononic Crystal with a Local Resonance Structure.

Using the piezoelectric (PZT) effect, energy-harvesting has become possible for phononic crystal (PnC). Low-frequency vibration energy harvesting is more of a challenge, which can be solved by local resonance phononic crystals (LRPnCs). A novel three-dimensional (3D) energy harvesting LRPnC is proposed and further analyzed using the finite element method (FEM) software COMSOL. The 3D LRPnC with spiral unit-cell structures is constructed with a low initial frequency and wide band gaps (BGs). According to the large vibration deformation of the elastic beam near the scatterer, a PZT sheet is mounted in the surface of that beam, to harvest the energy of elastic waves using the PZT effect. To further improve the energy-harvesting performance, a 5 × 5 super-cell is numerically constructed. Numerical simulations show that the present 3D super-cell PnC structure can make full use of the advantages of the large vibration deformation and the PZT effect, i.e., the BGs with a frequency range from 28.47 Hz to 194.21 Hz with a bandwidth of 142.7 Hz, and the maximum voltage output is about 29.3 V under effective sound pressure with a peak power of 11.5 µW. The present super-cell phononic crystal structure provides better support for low-frequency vibration energy harvesting, when designing PnCs, than that of the traditional Prague type.

Functional Lumen Imaging Probe Panometry Helps Identify Clinically Relevant Esophagogastric Junction Outflow Obstruction per Chicago Classification v4.0.

INTRODUCTION: Esophagogastric junction (EGJ) outflow obstruction (EGJOO) per Chicago Classification v4.0 (CCv4.0) represents a high-resolution manometry (HRM) diagnosis with uncertain clinical significance. This study aimed to evaluate functional lumen imaging probe (FLIP) panometry among patients with EGJOO on HRM/CCv4.0 to assess clinical/manometric associations and treatment outcomes. METHODS: An observational cohort study was performed on patients who completed FLIP during endoscopy and had an HRM/CCv4.0 diagnosis of EGJOO, i.e., HRM-EGJOO (inconclusive). Abnormal FLIP panometry motility classifications were applied to identify FLIP-confirmed conclusive EGJOO. Rapid drink challenge on HRM and timed barium esophagram were also assessed. Clinical management plan was determined by treating physicians and assessed through chart review. Clinical outcome was defined using the Eckardt score (ES) during follow-up evaluation: ES < 3 was considered a good outcome. RESULTS: Of 139 adult patients with manometric EGJOO (inconclusive per CCv4.0), a treatment outcome ES was obtained in 55 after achalasia-type treatment (i.e., pneumatic dilation, peroral endoscopic myotomy, laparoscopic Heller myotomy, or botulinum toxin injection) and 36 patients after other nonachalasia-type treatment. Among patients with conclusive EGJOO by HRM-FLIP complementary impression, 77% (33/43) had a good outcome after achalasia-type treatment, whereas 0% (0/12) of patients had a good outcome after nonachalasia-type treatment. Of patients with normal EGJ opening on FLIP, one-third of patients treated with achalasia-type treatment had a good outcome, while 9 of the 10 treated conservatively had a good outcome. DISCUSSION: FLIP panometry provides a useful complement to clarify the clinical significance of an HRM/CCv4.0 EGJOO diagnosis and help direct management decisions.

Myotomy technique and esophageal contractility impact blown-out myotomy formation in achalasia: an in silico investigation.

We used in silico models to investigate the impact of the dimensions of myotomy, contraction pattern, the tone of the esophagogastric junction (EGJ), and musculature at the myotomy site on esophageal wall stresses potentially leading to the formation of a blown-out myotomy (BOM). We performed three sets of simulations with an in silico esophagus model, wherein the myotomy-influenced region was modeled as an elliptical section devoid of muscle fibers. These sets investigated the effects of the dimensions of myotomy, differing esophageal contraction types, and differing esophagogastric junction (EGJ) tone and wall stiffness at the myotomy affected region on esophageal wall stresses potentially leading to BOM. Longer myotomy was found to be accompanied by a higher bolus volume accumulated at the myotomy site. With respect to esophageal contractions, deformation at the myotomy site was greatest with propagated peristalsis, followed by combined peristalsis and spasm, and pan-esophageal pressurization. Stronger EGJ tone with respect to the wall stiffness at the myotomy site was found to aid in increasing deformation at the myotomy site. In addition, we found that an esophagus with a shorter myotomy performed better at emptying the bolus than that with a longer myotomy. Shorter myotomies decrease the chance of BOM formation. Propagated peristalsis with EGJ outflow obstruction has the highest chance of BOM formation. We also found that abnormal residual EGJ tone may be a co-factor in the development of BOM, whereas remnant muscle fibers at myotomy site reduce the risk of BOM formation.NEW & NOTEWORTHY Blown-out myotomy (BOM) is a complication observed after myotomy, which is performed to treat achalasia. In silico simulations were performed to identify the factors leading to BOM formation. We found that a short myotomy that is not transmural and has some structural architecture intact reduces the risk of BOM formation. In addition, we found that high esophagogastric junction tone due to fundoplication is found to increase the risk of BOM formation.

Esophageal Dysmotility Is Associated With Disease Severity in Eosinophilic Esophagitis.

BACKGROUND & AIMS: An association of eosinophilic esophagitis (EoE) with esophageal dysmotility has been described, however, the related mechanism remains unclear. We aimed to evaluate clinical and physiologic characteristics, including esophageal distensibility, associated with secondary peristalsis in patients with EoE. METHODS: A total of 199 consecutive adult patients with EoE (age, 18-78 y; 32% female) who completed a 16-cm functional luminal imaging probe (FLIP) during endoscopy were evaluated in a cross-sectional study. FLIP panometry contractile response (CR) patterns were classified as normal CR or borderline CR if antegrade contractions were present, and abnormal CRs included impaired/disordered CR, absent CR, or spastic-reactive CR. The distensibility plateau of the esophageal body and esophagogastric junction distensibility was measured with FLIP. RESULTS: FLIP CR patterns included 68 (34%) normal CR, 65 (33%) borderline CR, 44 (22%) impaired/disordered CR, 16 (8%) absent CR, and 6 (3%) spastic-reactive CR. Compared with normal CRs, abnormal CRs more frequently had reduced esophageal distensibility (distensibility plateau <17 mm in 56% vs 32%), greater total EoE reference scores (median, 5; interquartile range [IQR], 3-6 vs median, 4; IQR, 3-5) with more severe ring scores, and a greater duration of symptoms (median, 10 y; IQR, 4-23 y vs median, 7 y; IQR, 3-15 y). Mucosal eosinophil density, however, was similar between abnormal CRs and normal CRs (median, 34 eosinophils/high-power field [hpf]; IQR, 14-60 eosinophils/hpf vs median, 25 eosinophils/hpf; IQR, 5-50 eosinophils/hpf). CONCLUSIONS: Although normal secondary peristalsis was observed frequently in this EoE cohort, abnormal esophageal CRs were related to EoE disease severity, especially features of fibrostenosis. This study evaluating secondary peristalsis in EoE suggests that esophageal wall remodeling, rather than eosinophilic inflammatory intensity, was associated with esophageal dysmotility in EoE.

Validation of Clinically Relevant Thresholds of Esophagogastric Junction Obstruction Using FLIP Panometry.

BACKGROUND & AIMS: This study aimed to assess the accuracy of functional luminal imaging probe (FLIP) panometry to detect esophagogastric junction (EGJ) obstruction assigned by high-resolution manometry (HRM) and the Chicago Classification version 4.0 (CCv4.0). METHODS: Six hundred eighty-seven adult patients who completed FLIP and HRM for primary esophageal motility evaluation and 35 asymptomatic volunteers (controls) were included. EGJ opening was evaluated with 16-cm FLIP during sedated endoscopy via EGJ-distensibility index (DI) and maximum EGJ diameter. HRM was classified according to CCv4.0 and focused on studies with a conclusive disorder of EGJ outflow (ie, achalasia subtypes I, II, or III; or EGJ outflow obstruction with abnormal timed barium esophagogram) or normal EGJ outflow. RESULTS: All 35 controls had EGJ-DI >3.0 mm2/mmHg and maximum EGJ diameter >16 mm. Per HRM and CCv4.0, 245 patients had a conclusive disorder of EGJ outflow, and 314 patients had normal EGJ outflow. Among the 241 patients with reduced EGJ opening (EGJ-DI <2.0 mm2/mmHg and maximum EGJ diameter <12 mm) on FLIP panometry, 86% had a conclusive disorder of EGJ outflow per CCv4.0. Among the 203 patients with normal EGJ opening (EGJ-DI ≥2.0 mm2/mmHg and maximum EGJ diameter ≥16 mm) on FLIP panometry, 99% had normal EGJ outflow per CCv4.0. CONCLUSIONS: FLIP panometry accurately identified clinically relevant conclusive EGJ obstruction as defined by CCv4.0 in patients evaluated for esophageal motor disorders. Thus, FLIP panometry is a valuable tool for both independent and complementary evaluation of esophageal motility.

Estimation of mechanical work done to open the esophagogastric junction using functional lumen imaging probe panometry.

In this study, we quantify the work done by the esophagus to open the esophagogastric junction (EGJ) and create a passage for bolus flow into the stomach. Work done on the EGJ was computed using functional lumen imaging probe (FLIP) panometry. Eighty-five individuals underwent FLIP panometry with a 16-cm catheter during sedated endoscopy including asymptomatic controls (n = 14), 45 patients with achalasia (n = 15 each, three subtypes), those with gastroesophageal reflux disease (GERD; n = 13), those with eosinophilic esophagitis (EoE; n = 8), and those with systemic sclerosis (SSc; n = 5). Luminal cross-sectional area (CSA) and pressure were measured by the FLIP catheter positioned across the EGJ. Work done on the EGJ (EGJW) was computed (millijoules, mJ) at 40-mL distension. Additionally, a separate method was developed to estimate the "work required" to fully open the EGJ (EGJROW) when it did not open during the procedure. EGJW for controls had a median [interquartile range (IQR)] value of 75 (56-141) mJ. All achalasia subtypes showed low EGJW compared with controls (P < 0.001). Subjects with GERD and EoE had EGJW 54.1 (6.9-96.3) and 65.9 (10.8-102.3) mJ, similar to controls (P < 0.08 and P < 0.4, respectively). The scleroderma group showed low values of EGJW, 12 mJ (P < 0.001). For patients with achalasia, EGJROW was the greatest and had a value of 210.4 (115.2-375.4) mJ. Disease groups with minimal or absent EGJ opening showed low values of EGJW. For patients with achalasia, EGJROW significantly exceeded EGJW values of all other groups, highlighting its unique pathophysiology. Balancing the relationship between EGJW and EGJROW is potentially useful for calibrating achalasia treatments and evaluating treatment response.NEW & NOTEWORTHY Changes in pressure and diameter occur at the EGJ during esophageal emptying. Similar changes can be observed during FLIP panometry. Data from healthy and diseased individuals were used to estimate the mechanical work done on the EGJ during distension-induced relaxation or, in instances of failed opening, work required to open the EGJ. Quantifying these parameters is potentially valuable to calibrate treatments and gauge treatment efficacy for subjects with disorders of EGJ function, especially achalasia.

Assessment of esophageal body peristaltic work using functional lumen imaging probe panometry.

The goal of this study was to conceptualize and compute measures of "mechanical work" done by the esophagus using data generated during functional lumen imaging probe (FLIP) panometry and compare work done during secondary peristalsis among patients and controls. Eighty-five individuals were evaluated with a 16-cm FLIP during sedated endoscopy, including asymptomatic controls (n = 14) and those with achalasia subtypes I, II, and III (n = 15, each); gastroesophageal reflux disease (GERD; n = 13); eosinophilic esophagitis (EoE; n = 9); and systemic sclerosis (SSc; n = 5). The FLIP catheter was positioned to have its distal segment straddling the esophagogastric junction (EGJ) during stepwise distension. Two metrics of work were assessed: "active work" (during bag volumes ≤ 40 mL where contractility generates substantial changes in lumen area) and "work capacity" (for bag volumes ≥ 60 mL when contractility cannot substantially alter the lumen area). Controls showed median [interquartile range (IQR)] of 7.3 (3.6-9.2) mJ of active work and 268.6 (225.2-332.3) mJ of work capacity. Patients with all achalasia subtypes, GERD, and SSc showed lower active work done than controls (P ≤ 0.003). Patients with achalasia subtypes I and II, GERD, and SSc had lower work capacity compared with controls (P < 0.001, 0.004, 0.04, and 0.001, respectively). Work capacity was similar between controls and patients with achalasia type III and EoE. Mechanical work of the esophagus differs between healthy controls and patient groups with achalasia, EoE, SSc, and GERD. Further studies are needed to fully explore the utility of this approach, but these work metrics would be valuable for device design (artificial esophagus), to measure the efficacy of peristalsis, to gauge the physiological state of the esophagus, and to comment on its pumping effectiveness.NEW & NOTEWORTHY Functional lumen imaging probe (FLIP) panometry assesses esophageal response to distension and provides a simultaneous assessment of pressure and dimension during contractility. This enables an objective assessment of "mechanical work" done by the esophagus. Eighty-five individuals were evaluated, and two work metrics were computed for each subject. Controls showed greater values of work compared with individuals with achalasia, gastroesophageal reflux disease (GERD), and systemic sclerosis (SSc). These values can quantify the mechanical behavior of the distal esophagus and assist in the estimation of muscular integrity.

Normal Functional Luminal Imaging Probe Panometry Findings Associate With Lack of Major Esophageal Motility Disorder on High-Resolution Manometry.

BACKGROUND & AIMS: A normal esophageal response to distension on functional luminal imaging probe (FLIP) panometry during endoscopy might indicate normal esophageal motor function. We aimed to investigate the correlation of normal FLIP panometry findings with esophageal high-resolution manometry (HRM) and outcomes of discrepant patients. METHODS: We performed a retrospective study using data from a registry of patients who completed FLIP during sedated endoscopy. We identified 111 patients with normal FLIP panometry findings (mean age, 42 y; 69% female) and corresponding HRM data. A normal FLIP panometry was defined as an esophagogastric junction (EGJ) distensibility index greater than 3.0 mm2/mm Hg, an absence of repetitive retrograde contractions, and a repetitive antegrade contraction pattern that met the Rule-of-6s: ≥6 consecutive antegrade contractions of ≥6-cm in length, at a rate of 6 ± 3 contractions per minute. HRM findings were classified by the Chicago classification system version 3.0. RESULTS: HRM results were classified as normal motility in 78 patients (70%), ineffective esophageal motility in 10 patients (9%), EGJ outflow obstruction in 20 patients (18%), and 3 patients (3%) as other. In patients with EGJ outflow obstruction based on HRM, the integrated relaxation pressure normalized on adjunctive swallows in 16 of 20 patients (80%), and in 8 of 9 patients (88%) who completed a barium esophagram and had normal barium clearance. Thus, although 23 of 111 patients (21%) with normal FLIP panometry had abnormal HRM findings, these HRMs often were considered to be false-positive or equivocal results. All patients with an abnormal result from HRM were treated conservatively. CONCLUSIONS: In a retrospective cohort study, we found that patients with normal FLIP panometry results did not have a clinical impression of a major esophageal motor disorder. Normal FLIP panometry results can exclude esophageal motility disorders at the time of endoscopy, possibly negating the need for HRM in select patients.

Esophagogastric Junction Opening Parameters Are Consistently Abnormal in Untreated Achalasia.

Achalasia is a disorder of impaired lower esophageal sphincter (LES) relaxation and failed peristalsis traditionally characterized by manometry.1 As impaired LES relaxation is a mechanism of reduced esophagogastric junction (EGJ) opening, abnormally reduced EGJ distensibility assessed with functional luminal imaging probe (FLIP) was reported among patients with untreated achalasia.2-5 Therefore, we aimed to describe the performance characteristics of EGJ opening parameters on FLIP panometry among a large cohort of treatment-naïve achalasia patients.

Prediction of Esophageal Retention: A Study Comparing High-Resolution Manometry and Functional Luminal Imaging Probe Panometry.

INTRODUCTION: High-resolution manometry (HRM) is generally considered the primary method to evaluate esophageal motility; functional luminal imaging probe (FLIP) panometry represents a novel method to do so and is completed during sedated endoscopy. This study aimed to compare HRM and FLIP panometry in predicting esophageal retention on timed barium esophagram (TBE). METHODS: A total of 329 adult patients who completed FLIP, HRM, and TBE for primary esophageal motility evaluation were included. An abnormal TBE was defined by a 1-minute column height >5 cm or impaction of a 12.5-mm barium tablet. The integrated relaxation pressure (IRP) on HRM was assessed in the supine and upright patient positions. Esophagogastric junction (EGJ) opening was evaluated with 16-cm FLIP performed during sedated endoscopy through EGJ-distensibility index and maximum EGJ diameter. RESULTS: Receiver operating characteristic curves to identify an abnormal TBE demonstrated AUC (95% confidence interval) of 0.79 (0.75-0.84) for supine IRP, 0.79 (0.76-0.86) for upright IRP, 0.84 (0.79-0.88) for EGJ-distensibility index, and 0.88 (0.85-0.92) for maximum EGJ diameter. Logistic regression to predict abnormal TBE showed odds ratios (95% confidence interval) of 1.8 (0.84-3.7) for consistent IRP elevation and 39.7 (16.4-96.2) for reduced EGJ opening on FLIP panometry. Of 40 patients with HRM-FLIP panometry discordance, HRM-IRP was consistent with TBE in 23% while FLIP panometry was consistent with TBE in 78%. DISCUSSION: FLIP panometry provided superior detection of esophageal retention over IRP on HRM. However, application of a complementary evaluation involving FLIP panometry, HRM, and TBE may be necessary to accurately diagnose esophageal motility disorders.

Classifying Esophageal Motility by FLIP Panometry: A Study of 722 Subjects With Manometry.

INTRODUCTION: Functional luminal imaging probe (FLIP) panometry can evaluate esophageal motility in response to sustained esophageal distension at the time of sedated endoscopy. This study aimed to describe a classification of esophageal motility using FLIP panometry and evaluate it against high-resolution manometry (HRM) and Chicago Classification v4.0 (CCv4.0). METHODS: Five hundred thirty-nine adult patients who completed FLIP and HRM with a conclusive CCv4.0 diagnosis were included in the primary analysis. Thirty-five asymptomatic volunteers ("controls") and 148 patients with an inconclusive CCv4.0 diagnosis or systemic sclerosis were also described. Esophagogastric junction (EGJ) opening and the contractile response (CR) to distension (i.e., secondary peristalsis) were evaluated with a 16-cm FLIP during sedated endoscopy and analyzed using a customized software program. HRM was classified according to CCv4.0. RESULTS: In the primary analysis, 156 patients (29%) had normal motility on FLIP panometry, defined by normal EGJ opening and a normal or borderline CR; 95% of these patients had normal motility or ineffective esophageal motility on HRM. Two hundred two patients (37%) had obstruction with weak CR, defined as reduced EGJ opening and absent CR or impaired/disordered CR, on FLIP panometry; 92% of these patients had a disorder of EGJ outflow per CCv4.0. DISCUSSION: Classifying esophageal motility in response to sustained distension with FLIP panometry parallels the swallow-associated motility evaluation provided with HRM and CCv4.0. Thus, FLIP panometry serves as a well-tolerated method that can complement, or in some cases be an alternative to HRM, for evaluating esophageal motility disorders.

Pumping Patterns and Work Done During Peristalsis in Finite-Length Elastic Tubes.

Balloon dilation catheters are often used to quantify the physiological state of peristaltic activity in tubular organs and comment on their ability to propel fluid which is important for healthy human function. To fully understand this system's behavior, we analyzed the effect of a solitary peristaltic wave on a fluid-filled elastic tube with closed ends. A reduced order model that predicts the resulting tube wall deformations, flow velocities, and pressure variations is presented. This simplified model is compared with detailed fluid-structure three-dimensional (3D) immersed boundary (IB) simulations of peristaltic pumping in tube walls made of hyperelastic material. The major dynamics observed in the 3D simulations were also displayed by our one-dimensional (1D) model under laminar flow conditions. Using the 1D model, several pumping regimes were investigated and presented in the form of a regime map that summarizes the system's response for a range of physiological conditions. Finally, the amount of work done during a peristaltic event in this configuration was defined and quantified. The variation of elastic energy and work done during pumping was found to have a unique signature for each regime. An extension of the 1D model is applied to enhance patient data collected by the device and find the work done for a typical esophageal peristaltic wave. This detailed characterization of the system's behavior aids in better interpreting the clinical data obtained from dilation catheters. Additionally, the pumping capacity of the esophagus can be quantified for comparative studies between disease groups.

Repetitive Antegrade Contractions: A novel response to sustained esophageal distension is modulated by cholinergic influence.

BACKGROUND & AIMS: A unique motor response to sustained esophageal distension, repetitive antegrade contractions (RACs), is observed using functional luminal imaging probe (FLIP) panometry. However, physiologic mechanisms related to this response are unexplored. This study aimed to evaluate the impact of cholinergic inhibition with atropine on the esophageal contractile response to sustained distention, including RACs, among healthy volunteers. METHODS: 8 asymptomatic volunteers (ages 22-45) were evaluated in a crossover study design with 16-cm FLIP positioned across the esophagogastric junction and distal esophagus during sedated upper endoscopy. The FLIP study involving stepwise volumetric distension was performed twice in each subject, at baseline and again after atropine (15 mcg/kg) was administered intravenously. FLIP panometry was analyzed to assess the contractile response to distension. RESULTS: Antegrade contractions, lumen-occluding contractions, and a RAC pattern were observed in 8/8, 8/8, and 7/8(88%) subjects, respectively, at baseline and in 5/8 (63%), 2/8 (25%) and 2/8 (25%) subjects after atropine. The rate of contractions in the RAC pattern was similar (6-7 contractions per minute) before and after atropine. Compared with the baseline study, distension-induced contractility was triggered at higher fill volumes after atropine. FLIP pressures were lower in response to volumetric filling after atropine than at baseline. CONCLUSIONS: The vigor and triggering of the esophageal contractile response to distension is reduced by cholinergic inhibition in asymptomatic controls. The observation that the rate of contractions did not change when patients developed repetitive contractile responses suggests that this rate is not modified by cholinergic inhibition once contractility is triggered.

Functional Luminal Imaging Probe Panometry Identifies Achalasia-Type Esophagogastric Junction Outflow Obstruction.

BACKGROUND & AIMS: The etiologies of esophagogastric junction outflow obstruction (EGJOO) vary, as do their therapeutic implications. We aimed to identify patients with EGJOO most likely to benefit from achalasia-type treatment, based on findings from functional luminal imaging probe (FLIP) panometry. METHODS: We performed a retrospective study of 34 patients who received a diagnosis of EGJOO from January 2015 through July 2017. Our analysis included patients who had been evaluated with timed barium esophagram, FLIP, or upper endoscopy. RESULTS: Among the 34 patients with idiopathic EGJOO, 7 (21%) had a normal esophagogastric junction distensibility index (EGJ-DI), based on FLIP panometry, and all had repetitive antegrade contractions. None of the patients had radiographic evidence of EGJOO (RAD-EGJOO), defined as liquid barium retention and/or barium tablet impaction. On the other hand, all 18 patients with RAD-EGJOO had an EGJ-DI less than 2 mm2/mm Hg. Nine of the 18 patients with RAD-EGJOO and EGJ-DI less than 2 mm2/mm Hg underwent achalasia-type treatment, and 77.8% of these (7 of 9) had improvements in Eckardt score. Of the 6 patients with a normal EGJ-DI (>3 mm2/mm Hg) who were treated conservatively and followed up, 100% had improvements in subsequent Eckardt scores. CONCLUSIONS: We found that FLIP is useful in identifying patients with EGJOO who are most likely to benefit from achalasia-type therapy. Patients with a low EGJ-DI responded well to achalasia-type treatment, whereas patients with normal results from FLIP panometry had good outcomes from conservative management. FLIP panometry might help select management strategies for this difficult population of patients.

Normal Values of Esophageal Distensibility and Distension-Induced Contractility Measured by Functional Luminal Imaging Probe Panometry.

BACKGROUND & AIMS: Functional luminal imaging probe (FLIP) panometry provides a comprehensive evaluation of esophageal functional at the time of endoscopy, including assessment of esophageal distensibility and distension-induced esophageal contractility. However, the few and inconsistent findings from healthy individuals pose challenges to the application of FLIP to research and clinical practice. We performed FLIP panometry in asymptomatic volunteers. METHODS: We performed a prospective study of 20 asymptomatic volunteers (ages, 23-44; 14 women) who were evaluated with 16-cm FLIP positioned across the esophagogastric junction (EGJ) and distal esophagus (and in 8 subjects also repositioned at the proximal esophagus) during sedated upper endoscopy. FLIP data were analyzed with a customized program that generated FLIP panometry plots and calculated the EGJ-distensibility index (DI) and distensibility plateaus (DP) of distal and proximal esophageal body. Distension-induced esophageal contractility was also assessed. RESULTS: The median EGJ-DI was 5.8 mm2/mm Hg (interquartile range [IQR], 4.9-6.7 mm2/mm Hg); all 20 subjects had an EGJ-DI greater than 2.8 mm2/mm Hg. The median DP values from all subjects tested were 20.2 mm (IQR, 19.8-20.8 mm) at the distal body, 21.1 mm (IQR, 20.3-22.9 mm) at the proximal body, and greater than 18 mm at both locations. Repetitive antegrade contractions (RACs) were observed in all 20 subjects; in 19 of 20 (95%) subjects, the RAC pattern persisted for 10 or more consecutive antegrade contractions. CONCLUSIONS: Normal parameters of FLIP panometry are EGJ-DI greater than 2.8 mm2/mm Hg, DP greater than 18 mm, and antegrade contractions that occur in a repetitive pattern (RACs)-these can be used as normal findings for esophageal distensibility and distension-induced contractility. These values can be used in comparative studies of esophageal diseases, such as achalasia and eosinophilic esophagitis, and will facilitate application of FLIP panometry to clinical practice.

Esophagogastric Junction Distensibility on Functional Lumen Imaging Probe Topography Predicts Treatment Response in Achalasia-Anatomy Matters!

INTRODUCTION: To compare the utility of the distensibility index (DI) on functional lumen imaging probe (FLIP) topography to other esophagogastric junction (EGJ) metrics in assessing treatment response in achalasia in the context of esophageal anatomy. METHODS: We prospectively evaluated 79 patients (at ages 17-81 years; 47% female patients) with achalasia during follow-up after pneumatic dilation, Heller myotomy, or per-oral endoscopic myotomy with timed barium esophagram, high-resolution impedance manometry, and FLIP. Anatomic deformities were identified based on consensus expert opinion. Patients were classified based on anatomy and EGJ opening to determine the association with radiographic outcome and Eckardt score (ES). RESULTS: Twenty-seven patients (34.1%) had an anatomic deformity-10 pseudodiverticula at myotomy, 7 epiphrenic diverticula, 5 sigmoid, and 5 sinktrap. A 5-minute column area of >5 cm was best associated with an ES of >3, with a sensitivity of 84% (P = 0.0013). Area under the curve for EGJ metrics in association with retention was as follows: DI, 0.90; maximal EGJ diameter, 0.76; integrated relaxation pressure, 0.64; and basal esophagogastric junction pressure, 0.53. Only FLIP metrics were associated with retention given normal anatomy (DI 2.4 vs 5.2 mm/mm Hg and maximal EGJ diameter 13.1 vs 16.6 mm in patients with and without retention, respectively; P values < 0.0001 and 0.002). Using a DI cutoff of <2.8 as abnormal, 40 of 45 patients with retention (P = 0.0001) and 23 of 25 patients with an ES of >3 (P = 0.02) had a low DI and/or anatomic deformity. With normal anatomy, 21 of 22 patients with retention had a low or borderline low DI. DISCUSSION: The FLIP DI is most useful metric for assessing the effect of achalasia treatment on EGJ opening. However, abnormal anatomy is an important mediator of outcome and treatment success will be modulated by anatomic defects that impede bolus emptying.

Esophageal motility classification can be established at the time of endoscopy: a study evaluating real-time functional luminal imaging probe panometry.

BACKGROUND AND AIMS: A novel device that provides real-time depiction of functional luminal image probe (FLIP) panometry (ie, esophagogastric junction [EGJ] distensibility and distension-induced contractility) was evaluated. We aimed to compare real-time FLIP panometry interpretation at the time of sedated endoscopy with high-resolution manometry (HRM) in evaluating esophageal motility. METHODS: Forty consecutive patients (aged 24-81 years; 60% women) referred for endoscopy with a plan for future HRM from 2 centers were prospectively evaluated with real-time FLIP panometry during sedated upper endoscopy. The EGJ distensibility index and contractility profile were applied to derive a FLIP panometry classification at the time of endoscopy and again (post-hoc) using a customized program. HRM was classified according to the Chicago classification. RESULTS: Real-time FLIP panometry motility classification was abnormal in 29 patients (73%), 19 (66%) of whom had a subsequent major motility disorder on HRM. All 9 patients with an HRM diagnosis of achalasia had abnormal real-time FLIP panometry classifications. Eleven patients (33%) had normal motility on real-time FLIP panometry and 8 (73%) had a subsequent HRM without a major motility disorder. There was excellent agreement (κ = .939) between real-time and post-hoc FLIP panometry interpretation of abnormal motility. CONCLUSIONS: This prospective, multicentered study demonstrated that real-time FLIP panometry could detect abnormal esophageal motility, including achalasia, at the endoscopic encounter. Additionally, normal motility on FLIP panometry was predictive of a benign HRM. Thus, real-time FLIP panometry incorporated with endoscopy appears to provide a suitable and well-tolerated point-of-care esophageal motility assessment.

Simulation studies of circular muscle contraction, longitudinal muscle shortening, and their coordination in esophageal transport.

On the basis of a fully coupled active musculomechanical model for esophageal transport, we aimed to find the roles of circular muscle (CM) contraction and longitudinal muscle (LM) shortening in esophageal transport, and the influence of their coordination. Two groups of studies were conducted using a computational model. In the first group, bolus transport with only CM contraction, only LM shortening, or both was simulated. Overall features and detailed information on pressure and the cross-sectional area (CSA) of mucosal and the two muscle layers were analyzed. In the second group, bolus transport with varying delay in CM contraction or LM shortening was simulated. The effect of delay on esophageal transport was studied. For cases showing abnormal transport, pressure and CSA were further analyzed. CM contraction by itself was sufficient to transport bolus, but LM shortening by itself was not. CM contraction decreased the CSA and the radius of the muscle layer locally, but LM shortening increased the CSA. Synchronized CM contraction and LM shortening led to overlapping of muscle CSA and pressure peaks. Advancing LM shortening adversely influenced bolus transport, whereas lagging LM shortening was irrelevant to bolus transport. In conclusion, CM contraction generates high squeezing pressure, which plays a primary role in esophageal transport. LM shortening increases muscle CSA, which helps to strengthen CM contraction. Advancing LM shortening decreases esophageal distensibility in the bolus region. Lagging LM shortening no longer helps esophageal transport. Synchronized CM contraction and LM shortening seems to be most effective for esophageal transport.