Although application of a 9V battery to the epicardial surface is a simple method of ventricular fibrillation induction, the fundamental mechanisms underlying this process remain unstudied. We used a combined experimental and modelling approach to understand how the interaction of direct current (DC) from a battery may induce reentrant activity within the rabbit ventricles and its dependence upon battery application timing and duration. A rabbit ventricular computational model was used to simulate 9V battery stimulation for different durations at varying onset times during sinus rhythm. Corresponding high-resolution optical mapping measurements were conducted on rabbit hearts with DC stimuli applied via a relay system. DC application to diastolic tissue induced anodal and cathodal make excitations in both simulations and experiments. Subsequently, similar static epicardial virtual-electrode patterns were formed which interacted with sinus beats, but did not induce reentry. Upon battery release during diastole, break excitations caused single ectopics, similar to application, before sinus rhythm resumed. Reentry induction was possible for short battery applications when break excitations were slowed and forced to take convoluted pathways upon interaction with refractory tissue from prior make excitations or sinus beats. Short-lived reentrant activity could be induced for battery release shortly-after a sinus beat for longer battery applications. In conclusion, the application of a 9V battery to the epicardial surface induces reentry through a complex interaction of break excitations following battery release with prior induced make excitations or sinus beats.
- cardiac modelling
- ventricular fibrillation
- optical mapping
- Copyright © 2013, American Journal of Physiology - Heart and Circulatory Physiology