Abstract 19817: Influence of the Purkinje Conduction System on the Ekg: A Modeling Study
Introduction - Computational modeling of cardiac electrophysiology (EP) is important for exploring the mechanisms that underlie fatal arrhythmias. Methods are limited for anatomically mapping the Purkinje conduction system (PCS) in whole hearts, and incorrect definition of the PCS geometry and/or conduction velocity leads to incorrectly modeled activation wavefronts, fractioned QRS, and T-wave inversion. The objective of this study was to design a PCS that resulted in the best simulated six-lead electrocardiogram (ECG), while maintaining consistency with known anatomy.
Methods - Diffusion tensor (DT) MRI was used to define gross anatomy and fiber orientations, combined with a cell model to build a finite element model of rabbit cardiac EP, from which the six-lead ECG was simulated. An in vivo six-lead rabbit ECG served as a reference for the computed ECG. The number and distribution of Purkinje-muscle junctions (PMJ) and the conduction velocity in RV, LV, and septal branches were varied. Whole-heart activation wavefronts and the resultant ECG were compared to the normal rabbit ECG. Parameters assessed included activation wavefront timing and QRS/T-wave morphology in a six-lead ECG.
Results - Forty combinations of PCS geometry and conduction speed were implemented. Increasing the density (from 34 to 399), uniformly distributing the PMJs, and a PCS with branches for earlier septal activation (3.0m/s) and a faster Purkinje conduction speed in the LV (3.0m/s) compared to the RV (2.1m/s) was necessary to produce the correct activation sequence, eliminate QRS fractionations, and produce the best T-wave morphology. The figure shows the comparison of the ECG output from V3 for three different iterations.
Conclusion - The reported Purkinje conduction speed is 0.8-2m/s, but a heterogeneous Purkinje conduction speed distribution combined with a high PMJ density is needed to produce computationally accurate ECGs.
- © 2012 by American Heart Association, Inc.