title: The effects of inflammation on heart rate and rhythm in a canine model of cardiac surgery.
abstract: BACKGROUND
  Heart rate (HR) and rhythm disturbances are common after cardiac surgery. This study tests the hypothesis that the inflammation caused by cardiac surgery is an underlying mechanism for postoperative changes in HR, rhythm, and HR variability (HRV).
  
  
  RESULTS
  Normal canines (n = 6 per group) were divided into 4 groups: (1) anesthesia, (2) sternotomy and pericardiotomy, (3) atriotomy, and (4) corticosteroids combined with an atriotomy. Continuous electrocardiographic recordings were done preoperatively and for 3 postoperative days. Electrophysiologic testing was done at the initial and terminal surgeries. C-reactive protein level was assessed at each study day, and tissue myeloperoxidase activity was assessed at the terminal study. Measurements of HRV were determined daily to detect changes in autonomic tone. Postoperatively, the HR increased in the pericardiotomy (P = .0005) and atriotomy (P = .001) groups and HRV decreased in both the groups. No significant change occurred in either the HR or HRV in the anesthesia (P = .52) and steroid (P = .16) groups. HRV (triangular index) on postoperative day 3 was correlated with the tissue myeloperoxidase levels (r = -.83; P = .0004). Autonomic blockade with atropine and esmolol resulted in an HR and HRV that were not significantly different between groups. Atrial premature beats occurred postoperatively in the all the groups except the anesthesia group and were independent of the degree of inflammation.
  
  
  CONCLUSIONS
  Cardiac surgery increases the postoperative HR by reducing HRV, mostly because of a reduction in vagal tone. Furthermore, the magnitude of these changes is dependent on the degree of inflammation and is normalized by corticosteroids.
authors: Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes Jewish Hospital, St Louis, Missouri 63110, USA. schuesslerr@wustl.edu
authors: Richard B
authors: RB
authors: Schuessler
authors: Yosuke
authors: Y
authors: Ishii
authors: Yulian
authors: Y
authors: Khagi
authors: Kelly
authors: K
authors: Diabagate
authors: John P
authors: JP
authors: Boineau
authors: Ralph J
authors: RJ
authors: Damiano
mesh_terms: D000305:Adrenal Cortex Hormones / Q000494:pharmacology; D000758:Anesthesia / Q000009:adverse effects / Q000379:methods; D000818:Animals; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects; D002097:C-Reactive Protein / Q000378:metabolism*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000379:methods; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D006339:Heart Rate / Q000187:drug effects*; D007249:Inflammation / Q000209:etiology / Q000378:metabolism; D008991:Monitoring, Physiologic / Q000379:methods; D059035:Perioperative Period / Q000379:methods; D009195:Peroxidase / Q000378:metabolism*; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism
chemical_list: D000305:Adrenal Cortex Hormones; D001285:Atropine; D002097:C-Reactive Protein; D009195:Peroxidase