Sinus Rhythm, the Autonomic Nervous System, and Quality of Life

Abstract

Much of our knowledge of the nature of atrial fibrillation (AF), and in particular the pattern of electrical activation in the atrium during AF, is derived from the testing of theory in animal models. Thus our current understanding of AF is based on Moe’s “multiple wavelet” hypothesis[1], developed from computer simulations, and the work of Allessie and Bonke, originally in a canine model of atrial flutter, demonstrating that re-entry can occur around a zone of functional block[2,3]. Mapping of atrial activation during AF, using multiplexed recordings from large arrays of electrodes, has only recently been performed in humans[4,5]. Although our theoretical understanding has benefitted greatly from such studies of induced AF in animals and chronic AF in humans, they do not tell us directly what causes AF in patients. Unfortunately, the presence of the arrhythmia itself renders conventional investigations of electrophysiology impossible during AF. However, valuable insights can be gained from patients with paroxysmal atrial fibrillation (PAF). In particular, observations regarding the timing of attacks in such patients have highlighted the possible aetiological role of the autonomic nervous system. Furthermore, comparisons can be made between PAF patients in sinus rhythm, and controls, indicating those electrophysiologic parameters which are associated with susceptibility to AF. In this chapter, we will discuss some of the lessons that can be learned about the nature and causes of clinical AF from observations made in patients during periods of sinus rhythm. Finally, we will address the important issues of quality of life in regard to paroxysmal arrhythmias, and their implications for treatment.