Sequential change in actions potential of rabbit epicardium during and following radiofrequency ablation

Action Potential Change During RF Ablation. Introduction: Although radiofre quency (RF) catheter ablation is used to treat certain cardiac arrhythmias, little is known regarding transient changes in cellular electrophysiology during and following RF delivery. Optical recordings of action potential (O AP) with voltage-sensitive dyes allow immunity from electrical noise during RF delivery. The purpose of this study was to clarify the possible synergi stic effects of both the thermal and electrotonic components of RF ablation . Methods and Results: In this study, OAPs were recorded on the epicardium of 16 isolated Langendorff-perfused rabbit hearts within or adjacent to lesio ns made by RF catheters, Hearts were perfused at room temperature with Tyro de's solution containing 2,3-butanedione monoxime and stained by the voltag e-sensitive dye di-4-ANEPPS. OAPs mere recorded before, during, and after R F pulses. Within the lesion, the action potential duration at 80% repolariz ation (APD(80)) of OAF decreased rapidly during the RF pulse, without recov ery following the pulse. In the border zone surrounding the lesion, the RF energy resulted in a rapid decrease in APD(80), which recovered promptly af ter the pulse (recovery time constant: 82 +/- 37 sec). APD(80) was nonlinea rly related to temperature during the RF ablation and responded faster to R F ablation than to purely thermal injury. Conclusion: The application of RF energy results in significant changes in myocardial cellular electrophysiologic properties. The RF energy has a comb ination of thermal and electrotonic effects on the myocardial tissue. The r esults of this in vitro study may illustrate the cellular basis for commonl y observed phenomena in clinical practice.