Functional Lumen Imaging Probe to Assess Geometric Changes in the Esophagogastric Junction Following Endolumenal Fundoplication
Toshitaka Hoppo, Barry P. Mcmahon*, Bart P. Witteman, Stefan J. Kraemer, Robert W. O'Rourke, Flemming H. Gravesen, Blair a. Jobe
Division of Thoracic and Foregut Surgery, The Heart, Lung and Esophageal Surgery Institute, University of Pittsburgh Medical Center, Pittsburgh, PA
Background: The functional lumen imaging probe (FLIP) uses impedance planimetry to measure the geometry of a distensible organ. The device employs a balloon which is filled with saline solution to determine the shape of the region and gauge its response to distension. By conversion of electrical impedance measurements into cross sectional areas (CSAs), real-time dynamic images can be displayed. The purpose of this study was to evaluate FLIP as a novel technology to determine structural changes at the esophagogastric junction (EGJ) following endolumenal fundoplication (ELF) and to compare these findings with accepted methods of objective esophageal testing. Methods: Baseline FLIP measurements were recorded at three different balloon distension-volumes (40, 50 and 60 cc) in 13 mongrel dogs. Eleven dogs were subjected to ELF using Esophyx™. Two different ELF techniques were tested. ELF1.0 and 2.0 were performed in 6 and 7 animals, respectively. Two dogs underwent a Sham procedure. FLIP measurements were repeated directly post-procedure and at 2 week follow-up. Three FLIP measurements were performed for each animal at each time point and the mean and standard deviation was calculated. Upper endoscopy, manometry and 48-hour pH testing were performed at each time point in every animal.Results: Immediately following the ELF procedures, there was as significant decrease in EGJ CSAs when compared to sham animals and baseline values (Table). Physiologically, this reduction in CSA correlated with an increase in lower esophageal sphincter (LES) resting pressure and length and normalization of distal esophageal pH compared to baseline values. However, at 2-week follow-up, the CSAs of both groups had returned to baseline values and this correlated with objective testing (i.e., worsening pH, decrease in resting pressure and degradation of endoscopic valve appearance). There was no significant difference in CSAs between ELF1.0 and ELF2.0 procedures at each time point. On objective testing, there was proportionally more degradation of the ELF1.0 valve on pH testing and manometry. Conclusion: As a single testing modality, FLIP is able to measure and display a change in tissue compliance at level of the EGJ following ELF as well as determine degradation of valve competence at two weeks. FLIP could be a useful tool to diagnose GERD and evaluate the outcome of anti-reflux surgery.
CSA (mm2) (SD) of the EGJ at a 50cc balloon fill before and after ELF
| Baseline | Immediate Post-procedure | 2-Weeks Follow-up | |
| Sham (n=3) | 81.0 (88.0) | 88.1 (15.6) | 110.0 (68.4) |
| ELF 1.0 (n=6) | 95.3 (58.7) | 38.9 (7.20) | 181.7 (37.0) |
| ELF 2.0 (n=5) | 125.0 (37.9) | 58.5 (38.0) | 113.5 (51.0) |
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