title: Can Monitoring Fetal Intestinal Inflammation Using Heart Rate Variability Analysis Signal Incipient Necrotizing Enterocolitis of the Neonate?
abstract: OBJECTIVE
  Necrotizing enterocolitis of the neonate is an acute inflammatory intestinal disease that can cause necrosis and sepsis. Chorioamnionitis is a risk factor of necrotizing enterocolitis. The gut represents the biggest vagus-innervated organ. Vagal activity can be measured via fetal heart rate variability. We hypothesized that fetal heart rate variability can detect fetuses with incipient gut inflammation.
  
  
  METHODS
  Prospective animal study.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Chronically instrumented near-term fetal sheep (n = 21).
  
  
  RESULTS
  Animals were surgically instrumented with vascular catheters and electrocardiogram to allow manipulation and recording from nonanesthetized animals. In 14 fetal sheep, inflammation was induced with lipopolysaccharide (IV) to mimic chorioamnionitis. Fetal arterial blood samples were drawn at selected time points over 54 hours post lipopolysaccharide for blood gas and cytokines (interleukin-6 and tumor necrosis factor-α enzymelinked immunosorbent assay). Fetal heart rateV was quantified throughout the experiment. The time-matched fetal heart rate variability measures were correlated to the levels of interleukin-6 and tumor necrosis factor-α. Upon necropsy, ionized calcium binding adaptor molecule 1+ (Iba1+), CD11c+ (M1), CD206+ (M2 macrophages), and occludin (leakiness marker) immunofluorescence in the terminal ileum was quantified along with regional Iba1+ signal in the brain (microglia). Interleukin-6 peaked at 3 hours post lipopolysaccharide accompanied by mild cardiovascular signs of sepsis. At 54 hours, we identified an increase in Iba1+ and, specifically, M1 macrophages in the ileum accompanied by increased leakiness, with no change in Iba1 signal in the brain. Preceding this change on tissue level, at 24 hours, a subset of nine fetal heart rate variability measures correlated exclusively to the Iba+ markers of ileal, but not brain, inflammation. An additional fetal heart rate variability measure, mean of the differences of R-R intervals, correlated uniquely to M1 ileum macrophages increasing due to lipopolysaccharide.
  
  
  CONCLUSIONS
  We identified a unique subset of fetal heart rate variability measures reflecting 1.5 days ahead of time the levels of macrophage activation and increased leakiness in terminal ileum. We propose that such subset of fetal heart rate variability measures reflects brain-gut communication via the vagus nerve. Detecting such noninvasively obtainable organ-specific fetal heart rate variability signature of inflammation would alarm neonatologists about neonates at risk of developing necrotizing enterocolitis and sepsis. Clinical validation studies are required.
authors.affiliation: 1Department of Obstetrics-Gynaecology, CHU Sainte-Justine Research Centre, l'Universite de Montréal, Montréal, QC, Canada. 2Division of Gastroenterology, Hepatology and Nutrition, CHU Sainte-Justine, Montréal, QC, Canada. 3Dynamical Analysis Laboratory, Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, ON, Canada. 4Department of Clinical Sciences, Faculty of veterinary medicine, Université de Montréal, St-Hyacinthe, QC, Canada. 5Division of Pathology, CHU Sainte-Justine, Montréal, QC, Canada. 6Dynamical Analysis Laboratory, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada. 7Centre de recherche en reproduction animale, l'Université de Montréal, St-Hyacinthe, QC, Canada. 8Department of Neurosciences, l'Université de Montréal, Montreal, QC, Canada.
authors.forename: Hai Lun
authors.initials: HL
authors.lastname: Liu
authors.forename: Luca
authors.initials: L
authors.lastname: Garzoni
authors.forename: Christophe
authors.initials: C
authors.lastname: Herry
authors.forename: Lucien Daniel
authors.initials: LD
authors.lastname: Durosier
authors.forename: Mingju
authors.initials: M
authors.lastname: Cao
authors.forename: Patrick
authors.initials: P
authors.lastname: Burns
authors.forename: Gilles
authors.initials: G
authors.lastname: Fecteau
authors.forename: André
authors.initials: A
authors.lastname: Desrochers
authors.forename: Natalie
authors.initials: N
authors.lastname: Patey
authors.forename: Andrew J E
authors.initials: AJ
authors.lastname: Seely
authors.forename: Christophe
authors.initials: C
authors.lastname: Faure
authors.forename: Martin G
authors.initials: MG
authors.lastname: Frasch
mesh_terms: D000818:Animals; D015148:Cardiotocography; D002821:Chorioamnionitis / Q000139:chemically induced / Q000276:immunology; D016207:Cytokines / Q000097:blood / Q000378:metabolism; D004195:Disease Models, Animal; D020345:Enterocolitis, Necrotizing / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006340:Heart Rate, Fetal; D006801:Humans; D007082:Ileum / Q000473:pathology; D007231:Infant, Newborn; D008070:Lipopolysaccharides; D008262:Macrophage Activation; D011247:Pregnancy; D011446:Prospective Studies; D012756:Sheep
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides