Autonomic Nervous System Modulation of the Epicardial Adipose Tissue in Heart Failure and Atrial Fibrillation

The epicardial adipose tissue (EAT) or epicardial fat, the visceral fat depot in the heart, contains intrinsic adrenergic and cholinergic nerves, which interact with the extrinsic cardiac sympathetic and parasympathetic nervous systems. These EAT nerves represent a significant source of several adipokines and other bioactive molecules, including norepinephrine and epinephrine. The production of these molecules is biologically relevant for the heart, because abnormalities in EAT secretory properties are implicated in the development of pathological conditions, including coronary atherosclerosis, atrial fibrillation, and heart failure. Because sympathetic hyperactivity and parasympathetic (cholinergic) derangement are associated with EAT dysfunction leading to a multitude of adverse cardiac conditions, such as heart failure, diastolic dysfunction, atrial fibrillation, etc., a number of recent studies have focused on exploring the autonomic regulation of EAT as it pertains to heart disease pathogenesis and progression. In this chapter, we provide an overview of these studies, immediately following brief introductions on the regulation of global cardiac function by the two branches of the autonomic nervous system (adrenergic and cholinergic).