Background: Atrial fibrillation (AF) is a common cardiac arrhythmia characterized by disorganized cardiac electrical activity. Defibrillation electrode placement has been shown to affect the amount of energy and number of shocks required to defibrillate. The objective of this study was to investigate the relationship between esophageal electric fields (EEFs) and atrial defibrillation thresholds (ADFTs) to determine the feasibility of using EEFs during a low-strength shock to predict patient-specific defibrillation electrode placements.
Methods: AF was induced and defibrillated according to a Bayesian four-shock protocol for 12-electrode placements in six pigs. EEFs were measured during each of the four shocks of the protocol and during a 1-J shock for each electrode placement. Squared EEFs (EEF2s) during all shocks were compared to the ADFTs using a linear regression.
Results:There was a negative relationship between EEF2s during the 1-J shocks and ADFTs, with median R2 values of 0.863 and 0.840 for anterior–anterior (AA) and anterior–posterior (AP) electrode placements, respectively. There was a strong, positive relationship between applied energy and EEF2s, with median R2 values of at least 0.866 for all animals. The placement with the highest EEF2 resulted in the lowest ADFT for both AA and AP placements in four of six pigs. In the other two animals, this held for one electrode set but not both.
Conclusions: There was a strong negative relationship between EEF2s during 1-J shocks and ADFTs for both AA and AP electrode placements. These preliminary results suggest that using EEF2s to predict patient-specific electrode placements is feasible. (PACE 2011;1–6)