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Changes in cerebral perfusion during third-generation implantable cardioverter defibrillator testing
Insights
Quantitative electroencephalography (QEEG) and transcranial Doppler (TCD) assess cerebral perfusion during implantable cardioverter-defibrillator (ICD) testing. Impaired cerebrovasomotor reactivity (CVR) predicts intolerance to ICD therapy, while intact CVR predicts tolerance.
Area of Science:
- Cardiology
- Neuroscience
- Biomedical Engineering
Background:
- Implantable cardioverter-defibrillators (ICDs) offer tiered therapy for ventricular arrhythmias.
- Current ICD programming lacks consideration for hemodynamic effects of dysrhythmias.
- Intelligent ICDs require assessment of hemodynamic consequences and end-organ perfusion.
Purpose of the Study:
- To evaluate quantitative electroencephalography (QEEG) and transcranial Doppler (TCD) for measuring cerebral perfusion during ICD testing.
- To determine if QEEG and TCD can predict tolerance or intolerance to programmed ICD therapy.
- To assess the utility of these techniques for evaluating hemodynamic sensors in future ICDs.
Main Methods:
- QEEG and TCD were used to monitor cerebral perfusion in patients undergoing ICD testing.
- Cerebrovasomotor reactivity (CVR) was assessed during hypotensive episodes and ventricular tachycardia.
- Near-infrared spectroscopy measured transcranial oxyhemoglobin saturation during ventricular tachycardia.
Main Results:
- Impaired CVR and changes in EEG (loss of alpha power, increased delta power) predicted intolerance to ICD therapy in 25/91 hypotensive episodes.
- Intact CVR prevented cerebral ischemia and predicted tolerance to programmed ICD therapy.
- These effects were more pronounced in the erect posture and during ventricular tachycardia.
Conclusions:
- QEEG and TCD are sensitive indicators of cerebral perfusion during ICD testing and programming.
- These techniques can predict patient tolerance to programmed ICD therapy.
- QEEG and TCD can serve as benchmarks for evaluating hemodynamic sensors in next-generation ICDs.
Abstract:
Third-generation implantable cardioverter defibrillators (ICDs) are designed to provide tiered therapy for ventricular tachycardia and ventricular fibrillation. At present, however, therapy prescription does not take into account the hemodynamic consequences of ventricular dysrhythmias. Design of "intelligent" devices depends on their ability to assess hemodynamic consequences of tachyarrhythmias and end-organ perfusion. Quantitative electroencephalography (QEEG) and transcranial Doppler flow provide sensitive and specific measures of cerebral perfusion during ICD testing and programming. In response to prolonged hypotension (> 15 seconds), transient loss of alpha power (i.e., increase in delta power) in the EEG spectrum, accompanied by impaired cerebrovasomotor reactivity (CVR), was observed in 25 of 91 hypotensive episodes in 15 patients, ages 36 to 72 years, predicting intolerance to the programmed ICD therapy. Conversely, intact CVR prevented ischemia, slowing in the EEG, and predicted tolerance to the therapy prescription. These changes were exaggerated in the erect posture during tilt-table ICD testing. During ventricular tachycardia, signs of cerebral hypoxia detected by QEEG and Doppler techniques were accompanied by a fall in transcranial oxyhemoglobin saturation measured by near-infrared spectroscopy. We conclude that transcranial Doppler and QEEG are sensitive indicators of cerebral perfusion. These techniques could be used as indexes of perfusion against which hemodynamic sensors for future ICDs could be evaluated.