Functional lumen imaging probe to assess geometric changes in the esophagogastric junction following endolumenal fundoplication.

BACKGROUND: The functional lumen imaging probe (FLIP) uses impedance planimetry to measure the geometry of a distensible organ. The purpose of this study was to evaluate FLIP as a method to determine structural changes at the gastroesophageal junction (GEJ) following transoral incisionless fundoplication (TIF) and compare these findings with the accepted methods of esophageal testing. METHODS: Two different approaches (TIF1.0 and 2.0) using the EsophyX™ device were performed in six and five animals, respectively. Three dogs underwent a sham procedure. FLIP measurements were performed pre- and post-procedure and at 2-week follow-up. Upper endoscopy, manometry, and 48-h pH testing were also performed at each time point. FLIP was performed in ten patients before and 3 months after TIF. RESULTS: Following TIF procedures, there was a significant decrease in cross-sectional area (CSA) of GEJ compared to baseline; however, the CSA of both groups returned to baseline at 2-week follow-up. The FLIP results were supported with pH testing and correlated highly with both measures of GEJ structural integrity (LES and cardia circumference). Following TIF in humans, there was a decrease in GEJ distensibility compared to baseline that persisted to the 3-month evaluation. CONCLUSION: FLIP is able to measure and display changes in tissue distensibility at the GEJ, and results correlate with established methods of testing. FLIP may represent a single testing modality by which to diagnose GERD and evaluate the outcome after antireflux surgery.

Viscosity of food boluses affects the axial force in the esophagus.

AIM: To study the effect of viscosity on axial force in the esophagus during primary peristalsis using a newly validated impedance-based axial force recording technique. METHODS: A probe able to simultaneously measure both axial force and manometry was positioned above the lower esophageal sphincter. Potable tap water and three thickened fluids were used to create boluses of different viscosities. Water has a viscosity of 1 mPa·s. The three thickened fluids were made with different concentrations of Clinutren Instant thickener. The viscous fluids were in appearance comparable to pudding (2 kPa·s), yogurt (6 kPa·s) and slush ice (10 kPa·s). Six healthy volunteers swallowed 5 and 10 mL of boluses multiple times. RESULTS: The pressure amplitude did not increase with the bolus viscosity nor with the bolus volume whereas the axial force increased marginally with bolus volume (0.1 > P > 0.05). Both techniques showed that contraction duration increased with bolus viscosity (P < 0.01). Association was found between axial force and pressure but the association became weaker with increasing viscosity. The pressure amplitude did not increase with the viscosity or bolus volume whereas the axial force increased marginally with the bolus size. CONCLUSION: This indicates a discrepancy between the physiological functions that can be recorded with axial force measurements and pressure measurements.

Axial force measurement for esophageal function testing.

The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

Transoral endoscopic fundoplication in the treatment of gastroesophageal reflux disease: the anatomic and physiologic basis for reconstruction of the esophagogastric junction using a novel device.

OBJECTIVE: To determine the safety, mechanism of action, immediate postprocedural anatomic impact on the esophagogastric junction, and short-term efficacy of the first entirely endolumenal antireflux procedure. BACKGROUND: A safe and effective endoscopic antireflux procedure remains elusive. Transoral endolumenal surgery has enormous potential for the treatment of gastroesophageal reflux disease (GERD) and other esophagogastric diseases. A canine model was used to study a novel endoscopic device, which allows for creation of an endoluminal fundoplication. METHODS: The transoral incisionless fundoplication (TIF) was performed in 21 canines in a phase I feasibility and safety study, and in 21 canines in a phase II study that included a detailed objective assessment of the effects of 2 variants of the TIF procedure (TIF 1.0 and TIF 2.0) versus sham on esophageal physiology and esophagogastric junction (EGJ) anatomy. RESULTS: In phase I, TIF provided a safe and feasible endolumenal therapy for GERD, with histologic data that demonstrated serosal fusion of approximated full-thickness tissue plications and durability of the fundoplication. TIF procedures effectively reduced cardia circumference and improved Hill classification grade. In phase II, the TIF 2.0 procedure achieved normalization of distal esophageal acid exposure and increased lower esophageal sphincter (LES) pressure and length based on objective testing over a 2-week period. TIF 2.0 demonstrated superior results to TIF 1.0, and valve appearance and location exhibited similarity to the Nissen fundoplication by vector volume analysis. CONCLUSIONS: The TIF procedure is safe and results in a durable and functional fundoplication as well as a platform for further development and modification of the procedure, which can be use to impact outcome. This work provides the foundation for human translation and assessment of long-term outcomes.