Symptom Relief After Gastric Electric Stimulation Treatment (Enterra Therapy) is Related to Percent Change in Gastric Retention in Diabetic but Not Post-Surgical or Idiopathic Gastroparesis : A Sensitivity Analysis With Logistic Regression Models

Abstract

G A A b st ra ct s may induce abnormal gastric slow wave patterns, however these patterns are poorly understood, because of the incomplete detail provided by previous recording methods (EGG / sparse-electrodes). In this study, we describe gastroparetic slow wave patterns in highresolution (HR) spatiotemporal detail. Methods: Patients with diabetic (n=10) and idiopathic (n=2) gastroparesis undergoing gastric stimulator implantation were enrolled (median age 41 yrs, mean ‘total symptom score’ 17±2 out of 20, mean 4-hr gastric emptying 28±19%). HR electrical mapping was performed using flexible arrays (256 electrodes; 4 mm spacing) placed over the anterior corpus and/or corpus-antrum border immediately after laparotomy. Propagation patterns were quantified by isochronal mapping. Results were compared to data from 12 patients with no known stomach pathology undergoing routine surgery, who were assessed in the same manner. Mean ± SEM are reported. Results: Slow wave propagation was exclusively normal in all controls (29 recordings; mean duration 4.65 min; freq. 2.8±0.3 c/min), whereas a range of abnormal propagation patterns were observed in 11/12 gastroparetics (21 recordings; mean duration 7.3 min). Diabetics: Abnormalities comprised incomplete conduction blocks (n=6 recordings; 3.0±0.2 c/min), corpus ectopic pacemakers (n=6; 3.5±0.3 c/min), antral focal events (n=2), and complete conduction block with escape (n=1; 2.2 c/ min). There was also one instance each of regular antral tachygastria (4 c/min), and disorganized / fibrillation-type behavior in the corpus with multiple wavelets propagating (n=1; 4.9 c/min). Wavefront collisions and retrograde propagation were each recorded in 5 patients. Idiopathics: Both patients demonstrated highly disorganized propagation with incomplete conduction blocks, competing ectopics, retrograde propagation, and colliding wavefronts. Conclusion: A diverse range of slow wave initiation and conduction abnormalities were revealed by HR mapping in patients with gastroparesis. Several dysrhythmic mechanisms are described here for the first time in humans. These abnormalities were spatially complex, meaning they might go undetected by lower resolution tests such as EGG. The clinical significance of these findings needs to be determined.