Why Ablation of Sites With Purkinje Activation Is Antiarrhythmic: The Interplay Between Fast Activation and Arrhythmogenesis

Figures

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  Figure 1. Computer simulations show that penetration of Purkinje fibers into the ventricular wall results in QRS slurring and short QRS50. (A) Torso model used for simulation. (B) The traces show simulated electrocardiograms (Lead II and III) with Purkinje fibers penetrating 2 mm (black) and 5 mm (red) into the ventricular wall. The dashed lines refer to the QRS duration at 50, 90, and 100% at 5 mm penetrance into the ventricular wall. Note that these moments of QRS50, QRS90, and QRS100 slightly differ at 2 mm penetrance because of different QRS amplitudes.

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  Figure 2. Purkinje-muscle junctions (PMJs) close to repolarization gradients may cause reentrant arrhythmias. (A) The graph shows time (vertical axis) and myocardial distances (horizontal axis). The blue line represents the repolarization time along the myocardial axis of beat 1 (supposedly a sinus activation). The orange and black lines show activation time along the myocardial axis of beat 2 (a ventricular premature activation). The orange line represents conduction through working myocardium and the black line through Purkinje fibers. If the PMJ activates the working myocardium far from the repolarization gradient (location A) the activation front propagates at low speed toward repolarization gradient, which will have disappeared when the activation front arrives (location C). If the PMJ activates the working myocardium close to the repolarization front (location B), the activation front meets still depolarized myocardium and conduction will block (location D) setting the stage for re-entry. Inset: A slowly conducting premature activation front (blue) arrives late at the site of prolonged repolarization causing activation whereas a fast conducting activation front (red) results in…