Endoscopic anterior fundoplication with the Medigus Ultrasonic Surgical Endostapler (MUSE): results from an ex-vivo simulation trial to assess the efficacy of the procedure by comparing stapling position and gastric yield pressures

Tae-Geun Gweon, MD, Kai Matthes, MD, PhD. Boston Children’s Hospital, Harvard Medical School

Background: GERD is the result of lower esophageal sphincter (LES) dysfunction caused by inappropriate transient LES relaxation or diminution of resting basal pressure. Recently, the Medigus Ultrasonic Surgical Endostapler (MUSE, Medigus, Omer, Israel), a combined video- and ultrasound-guided transoral surgical stapler, has been FDA-approved for endoscopic anterior fundoplication. Aim of this study is to determine the ideal position of the staples in relation to the gastroesophageal junction (GEJ) in a validated simulation model.

Materials and Methods: MUSE procedures were performed in the EASIE-R simulator (Endosim LLC, Hudson, MA) using fresh ex-vivo porcine stomachs. As a surrogate for LES function, the gastric yield pressure (GYP) was determined by inserting an 18-Gauge cannula into the stomach lumen, which was connected to a pressure transducer. The stomach was gradually filled with methylene-dyed normal saline using a roller pump. The GYP was determined by detection of reflux of the methylene-dyed water in the esophagus with a gastroscope positioned above the GEJ. We also compared the aimed staple location with the actual measured stapler location following the procedure.

Results: We performed eight MUSE procedures in eight ex-vivo porcine stomachs. We observed a discrepancy of 5-10mm between targeted distance and actual measured distance between stapling location and GEJ.

Distance between stapling position and GE junction in mm
Aimed 1st Stapling Position


Aimed 2nd Stapling Position


Measured 1st Stapling Position


Measured 2nd Stapling Position


Baseline GYP in mmHg Post-treatment GYP in mmHg
10 10 5 15 0 0
15 15 20 15 0 1
20 20 25 20 0 3
25 25 25 30 0 6
30 30 35 30 0 10
35 35 25 35 0 25
40 40 40 40 0 9
45 45 45 35 0 26

We observed a gradual increase in GYP with the distance of stapling position from the GEJ. Procedures with a distance of at least 30mm between GEJ and stapler location resulted in an improved LES valve mechanism with an increase in GYP in comparison to baseline. If the distance was less than 30mm the LES valve was insufficient (GYP less than 6 mm Hg)

Conclusions: Based on our experiments, there should be a minimal distance of 30 mm between each stapler location and the GEJ to create an efficient valve with the MUSE procedures. Limitations of this study are the small sample size and the use of an ex-vivo model with lack of intrinsic LES pressure.

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