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Spatial methods of epicardial activation time determination in normal hearts
Bonnie B Punske1, Quan Ni, Robert L Lux
1Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112-5000, USA. punske@cvrti.utah.edu
Annals of Biomedical Engineering
|September 16, 2003
Summary
Spatial methods for determining cardiac activation times are more accurate than the time derivative method, especially when dealing with fractionated electrograms during epicardial pacing.
Area of Science:
- Electrophysiology
- Cardiac Mapping
- Computational Biology
Background:
- Accurate determination of cardiac activation times is crucial for understanding heart rhythm disorders.
- Fractionated electrograms can introduce errors in traditional activation mapping methods.
- Epicardial pacing can lead to complex electrogram morphologies.
Purpose of the Study:
- To identify and characterize errors in activation time maps derived from fractionated electrograms using the time derivative method.
- To investigate the epicardial distribution of fractionated electrograms.
- To compare the accuracy of spatial methods versus the time derivative method for activation time determination.
Main Methods:
- Recording unipolar electrograms using high-density electrode grids (1-2 mm spacing) on canine epicardial surfaces.
- Estimating activation times using time derivative, maximum spatial gradient, and zero Laplacian methods.
- Comparing estimated activation times against a standard derived from potential maps.
Main Results:
- High correlations (R2 > 0.97) were observed between spatial methods and the standard for non-fractionated electrograms.
- Lower correlations (R2 = 0.85) were found for the time derivative method with fractionated electrograms.
- Spatial methods demonstrated an advantage over the time derivative method when fractionated electrograms were prevalent.
Conclusions:
- The time derivative method is less reliable for activation time mapping in the presence of fractionated electrograms.
- Spatial methods, such as gradient and Laplacian, offer improved accuracy for activation time determination in complex electrograms.
- These findings highlight the importance of selecting appropriate mapping techniques for specific electrophysiological conditions, particularly during epicardial pacing.