Mapping of the Atrial Neural Network: Autonomic Mechanisms Underlying Complex Fractionated Atrial Electrograms and the Substrate for Atrial Fibrillation

Seminal experimental studies showing that prolonged periods of atrial fibrillation (AF) can induce electrophysiological remodeling of the atria so that "AF begets AF," has become the basis for the understanding of the progression of AF in patients from paroxysmal to persistent to long-standing persistent forms of AF. Clinical studies which initially targeted pulmonary vein firing have refocused on the atrial substrate including the complex fractionated atrial electrograms (CFAEs) invariably found in all forms of AF. More recent experimental and clinical studies have shown that autonomic nerve elements on the heart may play a critical role in the initiation and maintenance of AF and the formation of CFAEs. In this chapter we used iso-potential mapping in the atrium as a starting point and a means of gaining insights into the autonomic factors underlying CFAEs and the substrate for AF. Subsequently we illustrated previous experimental findings to support the mapping evidence and suggested how these lines of experimental evidence correlate with clinical findings. In conclusion, we emphasize the role of the autonomic innervation of the atria in the pathophysiology of CFAEs and their association with the substrate for AF