Utilizing functional lumen imaging probe topography to evaluate esophageal contractility during volumetric distention: a pilot study

Abstract

Background The functional lumen imaging probe (FLIP) measures luminal cross-sectional area and pressure during volumetric distension. By applying novel customized software to produce FLIP topography plots, organized esophageal contractility can be visualized and analyzed. We aimed to describe the stimulus thresholds and contractile characteristics for distension-induced esophageal body contractility using FLIP topography in normal controls. Methods Ten healthy controls were evaluated during endoscopy with FLIP. During stepwise bag distension, simultaneous intra-bag pressure and luminal diameter measurements were obtained and exported to a MatLab program to generate FLIP topography plots. The distension volume, intra-bag pressure, and maximum esophageal body diameters were measured for the onset and cessation of repetitive antegrade contractions (RACs). Contraction duration, interval, magnitude, and velocity were measured at 8 and 3-cm proximal to the EGJ. Results Eight of ten subjects demonstrated RACs at a median onset volume of 29 ml (IQR, 25 - 38.8), median intra-bag pressure of 10.7 mmHg (IQR, 8.6 - 15.9), and median maximum esophageal body diameter of 18.5 mm (IQR, 17.5 - 19.6). Cessation of RACs occurred prior to completion of the distension protocol in three of the eight subjects exhibiting RACs. Values of the RAC-associated contractile metrics were also generated to characterize these events. Conclusions Distension-induced esophageal contractions can be assessed utilizing FLIP topography. RACs are a common finding in asymptomatic controls in response to volume distention and have similar characteristics to secondary peristalsis and repetitive rapid swallows.

Evaluation of Esophageal Motility Utilizing the Functional Lumen Imaging Probe

“…(10, 11) Contractions were described in terms of propagation direction (antegrade or retrograde) based on the tangent line placed on the onset of contraction. Contractions were considered repetitive (RACs or RRCs based on propagation direction) when ≥3 occurred consecutively.…”

Functional Lumen Imaging Probe for the Management of Esophageal Disorders: Expert Review From the Clinical Practice Updates Committee of the AGA Institute

“…The benefits of FLIP topography are the ability to define EGJ distensibility and function while simultaneously obtaining information regarding the contractile activity and distensibility of the esophageal body. This approach has been utilized to better characterize the motor activity in the body of the esophagus in achalasia subtypes where patients were categorized based on three distinct body patterns that consisted of repetitive antegrade contractions (RACs), repetitive retrograde contractions (RRCs) or absence of activity (Figure 2) 11, 12 .…”

“…FLIP may better characterize EGJ function as the degree of luminal opening is conceptually a more important determinant of bolus flow than LES relaxation. Additionally, evaluation of esophageal contractility (described in more detail below) with achalasia may also provide complementary clinical information to the standard achalasia assessment with esophageal manometry by further refining esophageal body contractile patterns and subtypes (Figure 2B) 11, 12 .…”

“…Serially-spaced diameter changes along the axial length of the balloon that are recorded by FLIP can be used to define contractile activity similar to high-resolution manometry 11 . A recent study comparing data acquired during a FLIP assessment during sedated endoscopy and standard high-resolution manometry suggests that FLIP can accurately diagnose achalasia and may be complementary to manometry in further refining the diagnosis of functional dysphagia (normal endoscopy/normal or borderline manometry) 12 .…”

Achalasia: It Is Not All Black and White

“…A further potential prognostic use for this device was borne out of modification of the technology termed FLIP topography whereby the catheter is positioned in the distal esophagus and software used to produce a visualization of esophageal body contractility with concurrent assessment of EGJ distensibility [78]. In a study performed by Carlson et al, esophageal body contractility including propagating contractions were observed in a proportion of patients with all subtypes of achalasia during catheter bag distension.…”