Double and triple sequential shocks reduce ventricular defibrillation threshold in dogs with and without myocardial infarction

Abstract

The role of optimal placement of electrodes and mode of shock delivery from a defibrillator was examined in dogs with and without myocardial infarction. Single, double and triple truncated exponential shocks separated by 1 ms were delivered through various electrode combinations and cardiac vectors after electrical induction of ventricular fibrillation. A single shock through a pathway not incorporating the interventricular septum (catheter electrodes or epicardial patches between anterior and posterior left ventricle) required the highest total energy (22.6 and greater than 26.4 J, respectively) and peak voltage (1,004 and greater than 1,094 V, respectively) to terminate ventricular fibrillation. A single shock through a pathway including the interventricular septum required lower total energy and peak voltage to defibrillate. Combinations of two sequential shocks between an intracardiac catheter electrode and anterior left ventricular epicardial patch, between the catheter electrode and subcutaneous extrathoracic plate and between three ventricular epicardial patches all significantly reduced total energy (7.7, 8.7 and 7.8 J, respectively) and peak voltage (424, 436 and 424 V, respectively) needed to defibrillate. Three sequential shocks exerted no significant additional reduction in total energy of the defibrillation threshold than did two sequential shocks. Infarcted canine heart required less peak voltage but not total energy to terminate ventricular fibrillation than did noninfarcted heart. Therefore, two sequential shocks over different pathways reduce both total energy and peak voltage required to terminate ventricular fibrillation.

Double Sequential Defibrillation for Refractory Ventricular Fibrillation: A Case Report

“…In EP labs, several studies noted significant reduction in epicardial defibrillation threshold and total energy required using double sequential shocks over single shocks. [4][5][6][7] Chang et al demonstrated that both healthy and infarcted canine hearts required less total energy to terminate ventricular fibrillation than single shocks. 5 Jones et al studied 21 patients volunteering to undergo induced ventricular fibrillation in the EP lab randomized to single or double sequential defibrillation attempts using epicardial leads.…”

Effects of biphasic waveforms on outcomes of cardiopulmonary resuscitation in a porcine model of prolonged cardiac arrest*

“…Two sequential shocks over different pathways reduced both total energy and peak voltage required to terminate VF (27), and defibrillation thresholds for sequential pulse shocks were all significantly lower. It is also reported that the sequential pathway shocks resulted in a significantly lower defibrillation threshold than simultaneous pathway shocks (28).…”

System for open-chest, multidirectional electrical defibrillation

“…Although other authors have found an even greater reduction of shock energy requirement using more than one stimulation direction (Chang et al, 1986;Jones et al, 1988;Kerber et al, 1994;Pagan-Carlo et al, 1998), one must consider that, in addition to the possible bias introduced by the use of different defibrillators for shock delivery in different pathways, some authors used temporally overlapping multidirectional shocks (Kerber et al, 1994;Pagan-Carlo et al, 1998), which was avoided in our study. Even though temporal superposition should further enhance excitatory recruitment, it should also increase the damaging potential of high-intensity field stimulation, which may result in failure of defibrillation due to arrhythmia reinduction and/or myocardial injury.…”