High Resolution Electrogastrography (HR-EGG) Assessment in Medically Refractory Gastroparesis

Gastroparesis is a chronic digestive disorder defined by the symptoms of nausea, vomiting, bloating, and abdominal pain in the setting of objectively delayed gastric emptying without mechanical gastric outlet obstruction. Gastroparesis is frequently identified after lung transplantation with incidence rates as high as 44%. Gastroparesis after lung transplantation is of significant concern as complications directly related to gastroparesis, specifically gastroesophageal reflux and aspiration, have been linked to the development of bronchiolitis obliterans syndrome, the primary cause of graft failure and the main cause of late morbidity and mortality following lung transplantation. Effective long-term therapy for medically refractory post-lung transplant gastroparesis represents a significant therapeutic challenge. Current therapies (such as botulinum toxin injection or surgical pyloromyotomy/bypass) are either limited by inconsistent efficacy or by their invasiveness. However, recent advances in endoscopic tunneling techniques have led to the development of gastric per-oral endoscopic myotomy (G-POEM). Initial reports of this technique for treatment of post-lung transplant gastroparesis are encouraging, with excellent preliminary safety and efficacy data. However, currently there are no clinical, endoscopic, or radiographic parameters that reliably predict which patients will respond to G-POEM. This is likely secondary to the multifactorial pathophysiology of gastroparesis. Secondary to this there is an unmet need to develop a widely deployable screening tool that is i) non-invasive, ii) able to reliably divide gastroparesis into pathophysiologic subgroups and iii) be able to guide effective treatments.

In a similar fashion to that of the brain and heart, waves generated at the stomach's surface propagate to the skin via volume conduction. These voltages can be measured with cutaneous electrodes, via gastric electrophysiology (EGG) noninvasively. However, the EGG has not encountered widespread clinical adoption as the ability to both reliably and consistently differentiate gastrocutaneous spatial dysrhythmias has not been possible. However, a novel 'high-resolution EGG' (HR-EGG), a multi-electrode array of 25 or more electrodes, has been shown to capture slow waves with high spatial resolution and extract meaningful spatial (as opposed to spectral) features, including the instantaneous slow wave direction at any given point in space. This coupled with novel deep convolutional neural network (CNN) frameworks and artifact rejection methods, have been able to reliably capture gastric myoelectricspatial abnormalities that correlate with symptom incidence and severity in gastroparesis patients.

Currently, a new generation of high-resolution electrogastrograms recording technology with 64-channel electrode array is being developed by Alimetry Limited that is able to provide body surface gastric mapping (BSGM). This BSGM is able to provide a more complete understanding of the origin and propagation of human gastric slow-wave activity non-invasively, such as frequency and pattern, in high spatiotemporal detail. The system also includes an App for tracking patient-reported symptoms throughout the test.

Our goal is to utilize this proprietary device to gauge if identification of gastric dysarrythmias can reliably identify patients that will respond to or will require definitive pyloric interventions such as a G-POEM procedure.