Relation of defibrillatory potential minima to post-defibrillatory activation

Management of patients with malignant arrhythmias occurring outside the hospital and the development of clinically applicable systems for internal defibrillation have stimulated interest in the factors influencing cardiac defibrillation. Using a directly coupled (DC) electrode and amplification scheme, the authors have developed a system capable of simultaneous three-dimensional mapping of both the high energy shock field created in the heart by defibrillation electrodes in addition to the mapping of the immediate postshock myocardial activation sequence. Experiments performed in vivo in anesthetized open-chest dogs revealed that successful defibrillation required 100% of the site examined to be depolarized, with the first post defibrillation beat originating in the area of minimum defibrillatory potential.<>