Acute Slow Wave Responses to High-Frequency Gastric Electrical Stimulation in Patients With Gastroparesis Defined by High-Resolution Mapping.
OBJECTIVE
High-frequency gastric electrical stimulation (GES) has emerged as a therapy for gastroparesis, but the mechanism(s) of action remain unclear. There is a need to refine stimulation protocols for clinical benefit, but a lack of accurate techniques for assessing mechanisms in clinical trials, such as slow wave modulation, has hindered progress. We thereby aimed to assess acute slow wave responses to GES in gastroparesis patients using high-resolution (HR) (multi-electrode) mapping, across a range of stimulation doses achievable by the Enterra stimulation device (Medtronic Inc., MN, USA).


METHODS
Patients with medically refractory gastroparesis (n = 8) undergoing device implantation underwent intraoperative HR mapping (256 electrodes). Baseline recordings were followed by four protocols of increasing stimulation intensity, with washout periods. Slow wave patterns, frequency, velocity, amplitude, and dysrhythmia rates were quantified by investigators blinded to stimulation settings.


RESULTS
There was no difference in slow wave pattern, frequency, velocity, or amplitude between baseline, washout, and stimulation periods (all p > 0.5). Dysrhythmias included ectopic pacemakers, conduction blocks, retrograde propagation, and colliding wavefronts, and dysrhythmia rates were unchanged with stimulation off vs. on (31% vs. 36% duration dysrhythmic; p > 0.5). Symptom scores and gastric emptying were improved at 5.8 month follow-up (p < 0.05).


CONCLUSIONS
High-frequency GES protocols achievable from a current commercial device did not acutely modulate slow wave activity or dysrhythmias. This study advances clinical methods for identifying and assessing therapeutic GES parameters, and can be applied in future studies on higher-energy protocols and devices.
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
Timothy R
TR
Angeli
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
Peng
P
Du
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
David
D
Midgley
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
Niranchan
N
Paskaranandavadivel
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
Shameer
S
Sathar
Department of Surgery, Mississippi Medical Center, Jackson, MS, USA.
Christopher
C
Lahr
Department of Gastroenterology, University of Louisville, Louisville, KY, USA.
Thomas L
TL
Abell
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.|Department of Surgery, Vanderbilt University, Nashville, TN, USA.
Leo K
LK
Cheng
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.|Department of Surgery, University of Auckland, Auckland, New Zealand.
Gregory
G
O'Grady
D000328:Adult; D001703:Biophysics; D004599:Electric Stimulation Therapy / Q000379:methods*; D004567:Electrodes, Implanted; D005260:Female; D005746:Gastric Emptying / Q000502:physiology; D018589:Gastroparesis / Q000628:therapy*; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D016896:Treatment Outcome
Diabetes mellitus; electrophysiology; high-resolution mapping; pacing; slow wave