Abstract: To control cardiac arrhythmias such as atrial fibrillation post-operatively, various non-ablative agents include polymers, fibroblasts, neurotoxins, and growth factors are introduced into one or more cardiac fat pads into the atrioventricular nodal fat pad in proximity to the autonomic ganglia therein. Any desired technique may be used for introducing the agent, including injection. The sinoatrial nodal fat pad target site and the atrioventricular nodal fat pad target site are identified using a stimulator, which may have electrodes coupled thereto or which may coupled to electrodes built into a delivery system.