Rate control during AF can be achieved by drugs (Ca++ blockers, digoxin, beta-blockers), or by AV nodal ablation. Drugs, as usual, have limitations, while the radical destruction of the AV node renders the patient permanently pacemaker-dependent.

In series of animal studies the investigators employed AVN-VNS delivered to the so-called AV nodal fat pad. Electrical stimulation of the fat pad resulted in release of neuromediator (acetylcholine) within the AV nodal domain. The investigators have demonstrated that this approach successfully and substantially slowed the ventricular rate during AF in both acute and chronic experiments without inflicting any damage on the AV node.

It is our hypothesis that temporary delivery of selective AVN-VNS in patients with AF will provide the benefits of reduced ventricular rate during the ongoing AF. The proposed study will be limited only to patients that are already in AF and in which open-heart surgical intervention has been scheduled. In these patients AVN-VNS will be delivered briefly (minutes) after the incision as a proof-of-concept therapy, with concomitant monitoring of the effects on the ventricular rate.

Based on the information obtained in this study, the investigators intend subsequently to test the AVN-VNS in a group of patients that develop AF post-operatively and remain in this status for several days after the surgery. A protocol for a separate study will be submitted if and when this becomes feasible.