Abstract 11132: Purkinje Early After-Depolarizations are Present in Long Duration Ventricular Fibrillation
Background: Reentry has been proposed as the mechanism of ventricular fibrillation (VF). Recent evidence suggests that triggered activity may play a role in maintaining VF as well, especially after VF >1 min, long duration VF (LDVF). The study directly recorded from Purkinje and myocardial fibers during LDVF on the dog endocardium to determine if early after-depolarizations (EAD) were present.
Methods: Ten isolated canine hearts were perfused with Tyrode's solution through the left main coronary artery. The left ventricle was opened from the septum and microelectrodes were inserted to record Purkinje potentials from a false tendon and myocardial potentials from an adjacent area (within 4 mm). Extracellular bipolar electrodes were placed with one electrode attached to the false tendon. The Purkinje and myocardial transmembrane action potentials were verified by their morphology, maximum upstroke, and activation time aligning with Purkinje and ventricular activation on the bipolar electrogram. 2, 3-butanedione monoxime removed ventricular motion to maintain stable microelectrode recordings. VF was induced, perfusion was halted, and recordings were made for more than 10 min.
Results: EADs were recorded from Purkinje fibers in 3 dogs (Figure). The activation rate of Purkinje and working myocardial cells was similar during the first min of VF. The activation rate decreased as VF continued with myocardial cells decreasing significantly faster than Purkinje cells (p<0.001).
Conclusion: The EADs recorded in Purkinje cells and the faster activation rate in Purkinje than myocardial cells during LDVF raise the possibility that triggered activity may contribute to LDVF maintenance.
- © 2011 by American Heart Association, Inc.