Abstract 1366: Transmural Incidence of Purkinje Activations during Ventricular Fibrillation
Anatomic features, such as Purkinje fibers, may play a role in ventricular fibrillation (VF). However, it is not known if Purkinje fibers are even active during VF. Purkinje fibers are confined to the subendocardium in dogs but are distributed transmurally in pigs. We recorded intramurally from both species to determine if Purkinje activations are present during VF.
Methods and Results: Transmural activations were recorded from 45 plunge needles inserted in 2 crisscross rows in the left ventricle throughout 10 min of electrically induced VF in 6 open-chest dogs and 6 open-chest pigs. Each plunge needle held 12 electrodes placed 2 mm apart. Recorded potentials and their temporal derivatives (5-point, least squares) were examined to identify Purkinje activations. Purkinje activation was identified as an initial sharp complex (1–2 ms in duration) preceding ventricular muscle activation. The area covered by the 4 distal electrodes of the plunge needles was called the endocardial zone, the middle 4 electrodes the mid-myocardial zone, and the proximal 4 electrodes the epicardial zone. Purkinje activations were only rarely identified during the first 2 min of VF. Between 2 and 10 min of VF (Table⇓), most Purkinje potentials were recorded from the endocardial zone in dogs but scattered among the three zones in pigs.
Conclusion: The finding that Purkinje activations are present after 2 min of VF in the anatomical regions in which Purkinje fibers are present in dogs and pigs indicates that the specialized conduction system is active after 2 min of VF.