title: Brief episodes of ventricular fibrillation do not influence postischemic cerebral perfusion assessed by positron emission tomography.
abstract: OBJECTIVE
  To establish the defibrillation threshold in patients receiving an implantable cardioverter defibrillator, at least three episodes of ventricular fibrillation are induced and converted back to regular rhythm, using direct current countershocks. The aim of this study was to examine the influence of repeated short episodes of ventricular fibrillation on global and regional cerebral perfusion.
  
  
  METHODS
  A prospective, descriptive study.
  
  
  METHODS
  A positron emission tomography laboratory at a university hospital.
  
  
  METHODS
  Four patients, admitted for defibrillation threshold tests 2 yrs after the implantation of a cardioverter defibrillator, were included in the study. Global and regional cerebral blood flow was measured by cerebral positron emission tomography, using an 15O-labeled tracer under propofol-induced general anesthesia. Electroencephalograms (EEGs) were concomitantly recorded.
  
  
  METHODS
  Induction and conversion of ventricular fibrillation.
  
  
  RESULTS
  No effect on global cerebral perfusion was observed after induced ventricular fibrillation lasting 21 +/- 3 secs. The average global cerebral perfusion was 23 +/- 1 mL/100 g/min after induction of anesthesia and 31 +/- 8 mL/100 g/min and 24 +/- 2 mL/100 g/min immediately after the termination of the first and second ventricular fibrillation episodes, respectively. Ten minutes after the second and the third threshold tests, global cerebral perfusion was 21 +/- 1 mL/100 g/min and 21 +/- 2 mL/100 g/min, respectively. Regional cerebral perfusion and EEGs were not influenced.
  
  
  CONCLUSIONS
  Short episodes of ventricular fibrillation did not induce any measurable effects on global and regional cerebral perfusion detectable by positron emission tomography 30 secs and 10 mins after restitution of sinus rhythm.
authors.affiliation: Department of Cardiothoracic Surgery, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Runsiö
authors.forename: L A
authors.initials: LA
authors.lastname: Brodin
authors.forename: L
authors.initials: L
authors.lastname: Eriksson
authors.forename: M
authors.initials: M
authors.lastname: Rosenqvist
authors.forename: S
authors.initials: S
authors.lastname: Samuelsson
authors.forename: S
authors.initials: S
authors.lastname: Stone-Elander
authors.forename: A
authors.initials: A
authors.lastname: Owall
authors.forename: M
authors.initials: M
authors.lastname: Ingvar
mesh_terms: D000368:Aged; D002540:Cerebral Cortex / Q000098:blood supply* / Q000000981:diagnostic imaging; D017147:Defibrillators, Implantable; D004569:Electroencephalography; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D014055:Tomography, Emission-Computed; D014693:Ventricular Fibrillation / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy