MEASUREMENT OF GASTROESOPHAGEAL DISTENSIBILITY AFTER MAGNETIC SPHINCTER AUGMENTATION: CLINICAL SIGNIFICANCE AND DEFINING NORMAL VALUES
Shahin Ayazi*, Philip Jackson, Anastasia Gorbunova, Yoshihiro Komatsu, Ali H. Zaidi, Fahim Habib, Madison Salvitti, Kirsten Newhams, Catherine M. Siegfried, Ping Zheng, Blair A. Jobe
Esophageal and Lung Institute, Allegheny Health Network, Pittsburgh, PA
Introduction:
The LINX device applies magnetic force to augment the lower esophageal sphincter. No studies have assessed the impact of magnetic sphincter augmentation (MSA) on distensibility of the gastroesophageal junction (GEJ). Functional luminal imaging probe (FLIP) panometry is a technology that enables evaluation of the luminal distensibility at the time of endoscopy. We designed the current study to measure the distensibility of the GEJ after MSA, to compare it to the GEJ distensibility after Nissen fundoplication (NF) and to define the normal values for distensibility after MSA.
Material and Methods:
Patients who underwent MSA and had excellent functional outcome and were free of postoperative dysphagia were selected. Patients were evaluated with an 8-cm FLIP balloon positioned across the GEJ during upper endoscopy at a mean of 13 (7.5) months after surgery. Minimum esophageal diameter (Dmin), cross-sectional area (CSA), and distensibility index (DI) were measured at 30 mL balloon distension, maintained for 30 seconds in all patients. DI was defined as the narrowest CSA divided by the corresponding pressure expressed in mm2/mmHg. Lower limit of normal for these parameters was defined using 10th percentile value. A group of patients who underwent NF and were free of GERD symptoms and postoperative dysphagia were used as a control group and GEJ distensibility was measured using same protocol at a mean follow-up of 10 (5.6) months. The FLIP values were then compared between groups using Mann-Whitney U test.
Results:
There were 34 patients [53% female, mean (SD) age: 57.1 (13.8)] who underwent MSA and had a post-operative FLIP. Post-MSA esophageal acid exposure was normalized in 84% of patients. The Nissen control group consisted of 12 patients [42% female, mean (SD) age: 51.4 (10.7)]. There were no immediate or long-term complications in either group.
MSA patients had a smaller Dmin [7.3 (2.5) vs. 10.2 (2.9), p=0.003], and CSA [45.7 (34.4) vs. 87.8 (51.1), p=0.002] when compared to those who underwent NF.
DI was less in patients after MSA when compared to those with NF [1.7 (1.1), 3.4 (2.6), p=0.036]. Patients with a smaller size LINX device (£14 magnetic beads) had a similar DI when compared to those with a larger device (>15 magnetic beads) [1.7 (1.1) vs. 1.8 (1.0), p=0.18]. Based on percentile cutoff points, FLIP values 0<0.6 mm2/mmHg for DI, 0<4.9 mm for Dmin and <19 mm2 for CSA should be considered abnormal after MSA.
Conclusion:
There is less GEJ distensibility after MSA when compared to Nissen fundoplication. Distensibility index is consistent across the range of LINX sizes and an index <0.6 mm2/mmHg should be considered abnormal. This threshold should be incorporated into decision-making when considering dilation in patients with persistent dysphagia >6 months after MSA.
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