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Tim Hsu-Han Wang*1, Gabriel Schamberg2, Stefan Calder2, Armen A. Gharibans2, Nicholas J. Evennett3, Grant R. Beban3, Greg O'Grady1,2
1The University of Auckland Faculty of Medical and Health Sciences, Auckland, Auckland, New Zealand; 2Alimetry Ltd, Auckland, New Zealand; 3Auckland City Hospital, Auckland, Auckland, New Zealand

Esophagectomy is a complex procedure performed for malignant and benign conditions. Procedural variations exist (including open vs laparoscopic vs robotic, two-stage Ivor-Lewis vs three-stage McKeown), but all involve the formation of a largely-thoracic gastric conduit. These may be associated with conduit dysfunction, early and/or persistent delayed gastric emptying, reflux and pain with no mechanical cause. There is emerging evidence that gastric electrical abnormalities contribute to this conduit dysfunction. A non-invasive medical device for body surface gastric mapping (BSGM) was recently developed to evaluate gastric electrical activity and function. This study aims to assess the feasibility of the novel BSGM device in the post-oesophagectomy stomach.

Patients who had undergone an esophagectomy at Auckland City Hospital (Auckland, New Zealand) between 2017-2022 were recruited following ethics approval. Exclusions comprised of patients undergoing adjuvant therapy or mechanical obstructions. The Gastric Alimetry System® (Auckland, New Zealand) was employed, comprising a stretchable array (8x8 electrodes; 196cm2) and cloud-based analytics platform. Following an overnight fast, 30 minutes of baseline recording was performed, followed by a meal challenge and 4 hours of post-prandial recordings. Symptoms were logged on a validated App. Spectral analysis of BSGM data was performed, with quantitative analysis including gastric frequency, BMI-adjusted amplitude, Gastric Alimetry Rhythm Index (a measure of rhythm stability) and meal response, compared to reference intervals in 110 healthy volunteers. Adverse events were also recorded.

6 patients were recruited, including one who subsequently had a total gastrectomy and colonic interposition. Array placement was based on post-operative cross-sectional imaging. Only one patient was symptomatic during the session, with nausea, pain and early satiation. Gastric activity was successfully captured in all patients except the patient who had the colonic interposition (negative control), having no discernible gastric activity. 4/5 patients with gastric conduits showed abnormalities on Gastric Alimetry: 3 with low amplitude activity (<22μV), 3 had low gastric frequency (<2.65 cycles/min), 2 had low Gastric Alimetry Rhythm Index associated with unstable pacemaking. There were no adverse events.

Gastric Alimetry is a safe and feasible technique to non-invasively assess the gastric myoelectrical activity and motility following esophagectomy, identifying changes in gastric function. The significance for the management of post-oesophagectomy gastric dysfunction can now be evaluated.

Figure 1 A. Patient who developed mild symptoms with normal gastric slow wave activity. B. Patient who developed sensorimotor symptoms after the meal challenge with abnormal gastric rhythm stability, low frequency, low BMI-adjusted amplitude and low meal response amplitude ratio.

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