Phase angle shift is a better determinant for catheter electrode contact with tissue compared to a catheter sensed
Thomas H Everett1, Israel Byrd, Emily Wilson
1Division of Cardiology and the Cardiovascular Research Institute, University of California San Francisco, USA.
Summary
Electrogram (EGM) magnitude is unreliable for guiding ablation catheter placement near heart tissue. Phase angle, a measure of capacitance shift, better predicts proximity and force, though optimal predictors require further research.
Area of Science:
- Electrophysiology
- Medical Devices
- Cardiac Ablation
Background:
- Electrogram (EGM) magnitude is conventionally used to guide ablation catheter placement.
- This method assumes EGM amplitude correlates with electrode proximity to cardiac tissue.
- The reliability of EGM for precise tissue contact and force assessment is debated.
Purpose of the Study:
- To compare the efficacy of electrogram (EGM) magnitude versus phase angle in predicting catheter proximity to heart tissue.
- To evaluate the suitability of EGM and phase angle for guiding ablation catheter tip placement.
- To determine if EGM or phase angle is a better indicator of catheter-tissue contact force.
Main Methods:
- Experimental study comparing electrogram (EGM) magnitude and phase angle.
- Measurements taken at varying distances from cardiac tissue using an ablation catheter.
- Analysis focused on the correlation between signal parameters and physical proximity/contact.
Main Results:
- Electrogram (EGM) magnitude showed poor correlation with proximity to tissue within millimeters of the surface.
- A small deviation from the tissue surface significantly alters energy delivery to the blood pool.
- Phase angle demonstrated a stronger correlation with both tissue proximity and catheter force.
Conclusions:
- Electrogram (EGM) magnitude is not a reliable sole indicator for guiding ablation catheter placement.
- Relying on EGM alone can lead to suboptimal energy delivery and ineffective ablation.
- Phase angle shows promise as a superior predictor, but further research is needed to optimize its use and combine it with other predictors.
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