title: Impact of transfusion of mediastinal shed blood on serum levels of cardiac enzymes.
abstract: BACKGROUND
  Infusion of shed mediastinal blood using an autotransfusion system is a widely applied technique of blood conservation in cardiac surgery. Serial determinations of serum creatine kinase (CK), its MB isoenzyme (CK-MB), and lactate hydrogenase (LDH) levels have been used to monitor perioperative myocardial injury. We investigated the impact of postoperative autotransfused blood infusion on serum levels of these enzymes.
  
  
  METHODS
  We performed a retrospective analysis of postoperative serum CK, CK-MB, and LDH levels of 300 patients who had elective uncomplicated aortocoronary bypass grafting. Shed mediastinal blood samples from 26 patients were analyzed for CK, CK-MB (enzymatic activity and mass), and LDH levels before infusion.
  
  
  RESULTS
  High postoperative serum levels of CK and LDH were observed after infusion of autotransfused blood. Shed mediastinal blood contained extremely high levels of these enzymes, particularly from patients who had internal mammary artery dissection. There was a strong correlation (r = 0.96) between measured CK-MB enzyme activities and those calculated from the CK-MB mass units.
  
  
  CONCLUSIONS
  Infusion of autotransfused blood containing high concentrations of CK and LDH results in elevated serum levels of these enzymes. Hemolysis, frequently present in shed blood, does not interfere with the routine biochemical assays for CK and CK-MB enzyme activities. Caution should be taken when postoperative cardiac enzyme levels are used to determine myocardial injury after aortocoronary bypass grafting if autotransfusion is used as a method of blood conservation.
authors.affiliation: Division of Cardiothoracic Surgery, Royal Victoria Hospital, Montreal, Quebec, Canada.
authors.forename: D M
authors.initials: DM
authors.lastname: Nguyen
authors.forename: B M
authors.initials: BM
authors.lastname: Gilfix
authors.forename: F
authors.initials: F
authors.lastname: Dennis
authors.forename: D
authors.initials: D
authors.lastname: Blank
authors.forename: D A
authors.initials: DA
authors.lastname: Latter
authors.forename: P L
authors.initials: PL
authors.lastname: Ergina
authors.forename: J E
authors.initials: JE
authors.lastname: Morin
authors.forename: B
authors.initials: B
authors.lastname: de Varennes
mesh_terms: D016063:Blood Loss, Surgical; D001804:Blood Transfusion, Autologous; D016022:Case-Control Studies; D004796:Clinical Enzyme Tests; D001026:Coronary Artery Bypass; D003402:Creatine Kinase / Q000097:blood*; D005260:Female; D006461:Hemolysis; D006801:Humans; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015428:Myocardial Reperfusion Injury / Q000175:diagnosis; D011182:Postoperative Care; D011184:Postoperative Period; D012189:Retrospective Studies
chemical_list: D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase