BRIEF EPISODES OF VENTRICULAR-FIBRILLATION DO NOT INFLUENCE POSTISCHEMIC CEREBRAL PERFUSION ASSESSED BY POSITRON-EMISSION-TOMOGRAPHY

Objectives: To establish the defibrillation threshold in patients rece iving an implantable cardioverter defibrillator, at least three episod es of ventricular fibrillation are induced and converted back to regul ar rhythm, using direct current countershocks, The aim of this study w as to examine the influence of repeated short episodes of ventricular fibrillation on global and regional cerebral perfusion, Design: A pros pective, descriptive study, Setting: A positron emission tomography la boratory at a university hospital, Patients: Four patients, admitted f or defibrillation threshold tests 2 yrs after the implantation of a ca rdioverter defibrillator, were included in the study. Global and regio nal cerebral blood flow was measured by cerebral positron emission tom ography, using an O-15-labeled tracer under propofol-induced general a nesthesia, Electroencephalograms (EEGs) were concomitantly recorded, I nterventions: Induction and conversion of ventricular fibrillation, Me asurements and Main Results: No effect on global cerebral perfusion wa s observed after induced ventricular fibrillation lasting 21 +/- 3 see s. The average global cerebral perfusion was 23 +/- 1 mL/100 g/min aft er induction of anesthesia and 31 +/- 8 mL/100 g/min and 24 +/- 2 mL/1 00 g/min immediately after the termination of the first and second ven tricular fibrillation episodes, respectively, Ten minutes after the se cond and the third threshold tests, global cerebral perfusion was 21 /- 1 mL/100 g/min and 21 +/- 2 mL/100 g/min, respectively. Regional ce rebral perfusion and EEGs were not influenced, Conclusion: Short episo des of ventricular fibrillation did not induce any measurable effects on global and regional cerebral perfusion detectable by positron emiss ion tomography 30 sees and 10 mins after restitution of sinus rhythm.