title: The impact of surgical excisions on human gastric slow wave conduction, defined by high-resolution electrical mapping and in silico modeling.
abstract: BACKGROUND
  Gastric contractions are coordinated by slow waves, generated by interstitial cells of Cajal (ICC). Gastric surgery affects slow wave conduction, potentially contributing to postoperative gastric dysfunction. However, the impact of gastric cuts on slow waves has not been comprehensively evaluated. This study aimed to define consequences of surgical excisions on gastric slow waves by applying high-resolution (HR) electrical mapping and in silico modeling.
  
  
  METHODS
  Patients undergoing gastric stimulator implantation (n = 10) underwent full-thickness stapled excisions (25 × 15 mm, distal corpus) for histological evaluation, enabling HR mapping (256 electrodes; 36 cm(2) ) over and adjacent to excisions. A biophysically based in silico model of bidirectionally coupled ICC networks was developed and applied to investigate the underlying conduction mechanisms and importance of excision orientation.
  
  
  RESULTS
  Normal gastric slow waves propagated aborally (3.0 ± 0.2 cpm). Excisions induced complete conduction block and wavelets that rotated around blocks, then propagated rapidly circumferentially distal to the blocks (8.5 ± 1.2 vs normal 3.6 ± 0.4 mm/s; p < 0.01). This 'conduction anisotropy' homeostatically restored antegrade propagating gastric wavefronts distal to excisions. Excisions were associated with complex dysrhythmias in five patients: retrograde propagation (3/10), ectopics (3/10), functional blocks (2/10), and collisions (1/10). Simulations demonstrated conduction anisotropy emerged from bidirectional coupling within ICC layers and showed transverse incision length and orientation correlated with the degree of conduction distortion.
  
  
  CONCLUSIONS
  Orienting incisions in the longitudinal gastric axis causes least disruption to electrical conduction and motility. However, if transverse incisions are made, a homeostatic mechanism of gastric conduction anisotropy compensates by restoring aborally propagating wavefronts. Complex dysrhythmias accompanying excisions could modify postoperative recovery in susceptible patients.
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
authors.forename: P
authors.initials: P
authors.lastname: Du
authors.affiliation: Division of Surgery, Westmead Hospital, Sydney, NSW, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Hameed
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
authors.forename: T R
authors.initials: TR
authors.lastname: Angeli
authors.affiliation: Department of Surgery, Mississippi Medical Center, Jackson, MI, USA.
authors.forename: C
authors.initials: C
authors.lastname: Lahr
authors.affiliation: Department of Gastroenterology, University of Louisville, Louisville, KY, USA.
authors.forename: T L
authors.initials: TL
authors.lastname: Abell
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.|Department of Surgery, Vanderbilt University, Nashville, TN, USA.
authors.forename: L K
authors.initials: LK
authors.lastname: Cheng
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.|Department of Surgery, University of Auckland, Auckland, New Zealand.
authors.forename: G
authors.identifier: http://orcid.org/0000-0002-5998-1080
authors.initials: G
authors.lastname: O'Grady
mesh_terms: D000328:Adult; D003198:Computer Simulation; D013505:Digestive System Surgical Procedures / Q000009:adverse effects*; D055724:Electrophysiological Phenomena / Q000502:physiology*; D005260:Female; D005769:Gastrointestinal Motility / Q000502:physiology*; D006801:Humans; D056885:Interstitial Cells of Cajal / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D013270:Stomach / Q000503:physiopathology* / Q000601:surgery*
keywords: electrophysiology; incisions; interstitial cells of Cajal; motility; stomach