64 USE OF INTERMEDIATE TEMPERATURES TO REVERT ATRIAL FIBRILLATION

Previous work has shown the ability of iced saline to revert acetylcholine-induced atrial fibrillation in the pig model. The present study investigated whether room temperature saline could also be effective for this purpose. The left atria of 3 Sus domesticus 25-30 kg were exposed by left thoracotomy, and atrial fibrillation induced by direct application of 1:100 acetylcholine solution accompanied by gentle stroking of the tissue. The time duration of the resultant arrhythmias was measured during no intervention and applications of room temperature (22°C) and iced saline (4°C) compresses to the exposed portion of the atria. A total of 16 episodes each for control, room, and iced interventions were randomly conducted. In control episodes, an average of 3 minutes was recorded. In room temperature, the average dropped to 1.6 minutes, and for the iced intervention was 1.2 minutes. The data were examined with GraphPad InStat version 3.05. Normality was checked using the Kolmogorov-Smirnov test and then analyzed by a one-way analysis of variance (ANOVA). There appeared to be a linear trend of efficacy with temperature. Although the difference between the iced saline and room temperature interventions was not statistically significant, there were significant differences between the control (37°C) and iced saline (4°C) times and between control and room temperature (22°C). We conclude that atrial chilling to revert atrial fibrillation is feasible even using temperatures more modest than iced saline. (Figure)