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Brief episodes of ventricular fibrillation do not influence postischemic cerebral perfusion assessed by positron
M Runsiö1, L A Brodin, L Eriksson
1Department of Cardiothoracic Surgery, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
Insights
Short episodes of ventricular fibrillation (VF) during implantable cardioverter-defibrillator testing did not affect brain blood flow. This study found no significant changes in global or regional cerebral perfusion following induced VF in patients.
Area of Science:
- Neuroscience
- Cardiology
- Medical Imaging
Background:
- Implantable cardioverter-defibrillators (ICDs) require defibrillation threshold testing.
- This involves inducing ventricular fibrillation (VF) and converting it with electrical shocks.
- The impact of induced VF on cerebral perfusion is not well understood.
Purpose of the Study:
- To investigate the effect of short, induced episodes of ventricular fibrillation on cerebral perfusion.
- To assess both global and regional cerebral blood flow changes.
- To evaluate these changes in patients undergoing defibrillation threshold testing for ICDs.
Main Methods:
- Prospective, descriptive study at a university hospital.
- Four patients undergoing ICD defibrillation threshold tests were included.
- Cerebral blood flow measured using 15O-labeled tracer positron emission tomography (PET) under general anesthesia.
- Electroencephalograms (EEGs) were recorded concurrently.
Main Results:
- No significant effect on global cerebral perfusion was observed after induced VF episodes (21 +/- 3 seconds).
- Global cerebral perfusion values remained stable immediately after VF termination and at 10 minutes post-procedure.
- Regional cerebral perfusion and EEGs showed no measurable influence.
Conclusions:
- Short episodes of induced ventricular fibrillation do not appear to cause measurable changes in global or regional cerebral perfusion.
- Findings suggest that current defibrillation threshold testing protocols are safe regarding cerebral blood flow.
- Positron emission tomography is a suitable method for assessing cerebral perfusion during these tests.
Objectives:
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.
Design:
A prospective, descriptive study.
Setting:
A positron emission tomography laboratory at a university hospital.
Patients:
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.
Interventions:
Induction and conversion of ventricular fibrillation.
Measurements And Main 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.
Conclusion:
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.