Termination of Atrial Fibrillation With Epicardial Cooling in the Oblique Sinus.

OBJECTIVES

This study aimed to determine if epicardial cooling could repeatedly terminate induced atrial fibrillation (AF) in a canine heart.

BACKGROUND

Rapid termination of AF could control symptoms and prevent atrial remodeling; however, defibrillation by internal electrical cardioversion is not tolerable to most patients. Cooling of the epicardium slows atrial conduction and may provide a less painful method to quickly terminate AF.

METHODS

AF was induced with atrial myocardial epinephrine injections and rapid atrial pacing in an open-chest canine. Attempts at termination were performed with a small metal device that was either cooled to 5°C or kept at body temperature (control module). The device was placed on the epicardial surface in the oblique sinus. The time from device contact to termination of AF was recorded.

RESULTS

In 5 different canine studies, there were 57 attempts at AF termination with either a 5°C module (34 attempts) or a control module (23 attempts). The median (interquartile range [IQR]) time to AF termination was 24 s (IQR: 15 to 35 s) for the 5°C therapy and 100 s (IQR: 47 to 240 s) for the body temperature treatments (p < 0.001). In the control group, there were 8 AF episodes that continued up to 4 min. Subsequent application of the 5°C cooling module terminated AF in all cases.

CONCLUSIONS

Epicardial cooling in the oblique sinus is effective for repeated termination of AF in a canine heart. If reproduced in human studies, epicardial cooling with an implantable device may provide a method for management of patients with AF.