What Are the Optional Parameters of the Enterra Gastric Electrical Stimulation to Achieve Long Term Symptom Control in Gastroparetic Patients?

Abstract

Purpose: Gastric electrical stimulation (GES) with Enterra Therapy (ET) has been proven as a safe and effective treatment option in patients with medically refractory gastroparesis (GP). Limited data is available regarding the electrical parameters and settings utilized that can result in successful long term out-come for GES therapy. To analyze the differences in stimulation parameters from the time of initiation of neuromodulation to the last follow-up (up to 10 years) in three, etiologically distinct groups of GP who were implanted at one center, and followed up by one team of investigators. Methods: 221 patients diagnosed with GP (164 F) mean age 38 (18-70) [142 diabetics (DM), 48 idiopathics (ID), 31 post-surgical (PS)] were implanted with GES at our site between 1998-2008. Baseline stimulation settings were as follows: frequency- 14 Hz, current (I) 5 mA, pulse width 330 μsec, and 0.1 sec ON, 5.0 sec OFF. At each follow-up visit (1-2 per year), GP symptoms were evaluated and stimulation parameters reviewed. Standardized protocol was used to adjust stimulation settings based on impedance (R) reading and symptom control. Results: The programming information (median readings) from 185 patients (119 DM, 39ID, 27 PS) for comparing baseline (programmed at surgery) to last follow-up (mean 55 months; range 12-131) is in the Table. 60%DM, 49%ID, 59%PS achieved at least 50% reduction in their GP symptoms, and 32%, 23%, 22%, respectively, required no changes in their settings to reach this outcome. Voltage adjustment with subsequent change in current ≥10 mA took place in 10% of DM, 15% of ID, and 14% of PS. Four DM, 3 ID and 1 PS patient utilized 1-2 sec ON and 3-4 sec OFF. The frequency of stimulation was not changed in any of our Enterra patients. Four patients needed battery replacements during follow-up (between 6-7 years after initiating Enterra). Interestingly, the baseline voltage in DM was significantly lower than in ID (P<0.05) but similar to voltage in PS group.TableConclusion: 1. During long term follow-up of GES patients, stimulation parameters were changed resulting in a significant voltage increase, which was similar in the 3 groups DM, ID and PS. 2. Better symptom improvement among patients with DM and PS etiologies could be related to their lower baseline voltage and follow-up resistance values. 3. Our data suggests that a “conservative” approach to changing parameters during interrogation of the gastric stimulator, based on GI symptoms status results in effective clinical outcomes. Disclosure: Dr Irene Sarosiek - Consultant: Medtronic, Inc. Dr McCallum - Consultant: Medtronic, Inc.