O-BN08 Quality of Life 21 Years Following Gastric Pacing/ Gastric Electrical Stimulation for Gastroparesis – A real life data

Background Gastroparesis is defined as delayed emptying of the stomach in the absence of mechanical obstruction. Gastroparesis symptoms ranging from nausea, vomiting, bloating and abdominal pain with significant impact on overall quality of life (QALY). Gastric electrical stimulation (GES) for gastroparesis has been used in clinical practice since 1998 and was initially licensed as a “humanitarian” treatment when all else had failed. In the last two decades, it has been increasingly used in the treatment of refractory gastroparesis. We have been performing GES for refractory Gastroparesis since 2000 and we present our data on symptoms, quality of life and resource utilization Methods A prospective consecutive cohort study at a single center from December 2000 to July 2021 has been conducted. Data on patient demographics (gender and age), comorbidities, aetiology, the method of surgery, pre and post hospital stay, pre and post-operative SF-36 questionnaire (QALY) and symptom score (Likert Score), adjunct intervention, feeding regimen, mortality and morbidity were collated and subjected to student t-test for parametric data, the Wilcoxon test for non-parametric data, and McNemar’s test for binomial data Results A total of 162 patients underwent GES. There were 118 females. The median age was 36.5 years (range 6-80). Ninety-two patients were Idiopathic, 63 were Diabetic and 7 Post-Surgical. Overall QALY improved from a mean of 190/500 to 415/500(p = <0.001) with significant improvement in nausea (p = <0.001), abdominal pain (p = 0.005) and bloating (p = 0.001) severity score prior and following surgery. Number of hospital admissions (median) reduced post GES insertion from six to zero per year (p = 0.002). The median length of stay was 3 days (range 1-45) and follow up was up to 129 months (6-252). There was no mortality from the procedure. Conclusions This is one of a few long-term studies looking at the outcome following GES for Gastroparesis. Our data shows that GES is a safe procedure with very little morbidity and no mortality. It improves symptoms and quality of life. It also reduces the health care utilization for these patients. The effects of GES are also very durable and hence should be considered as a mainstream treatment for patients with refractory gastroparesis.

Neurons in the Nucleus Tractus Solitarius are Selective to the Orientation of Gastric Electrical Stimulation

Gastric electrical stimulation (GES) is a bioelectric intervention for gastroparesis, obesity, and other functional gastrointestinal disorders. In a potential mechanism of action, GES activates the nerve endings of vagal afferent neurons and induces the vago-vagal reflex through the nucleus tractus solitarius (NTS) in the brainstem. However, it is unclear where and how to stimulate in order to optimize the vagal afferent responses. To address this question with electrophysiology in rats, we applied mild electrical currents to two serosal targets on the distal forestomach with dense distributions of vagal intramuscular arrays that innervated the circular and longitudinal smooth muscle layers. During stimulation, we recorded single and multi-unit responses in NTS and evaluated how the recorded responses depended on the stimulus orientation and amplitude. We found that NTS responses were highly selective to the stimulus orientation for a range of stimulus amplitudes. The strongest responses were observed when the applied current flowed in the same direction as the intramuscular arrays in parallel with the underlying smooth muscle fibers. Our results suggest that gastric neurons in NTS may encode the orientation-specific activity of gastric smooth muscles relayed by vagal afferent neurons. This finding suggests that the orientation of GES is critical to effective engagement of vagal afferents and should be considered in light of the structural phenotypes of vagal terminals in the stomach.