I n 1628, William Harvey hinted at a link between the brain and the heart when he wrote, "For every affection of the mind that is attended with either pain or pleasure, hope or fear, is the cause of an agitation whose influence extends to the heart."1 For the past half century, numerous anatomic and physiological studies of cardiac autonomic nervous system (ANS) 2-6 have investigated this link and found it to be very complex. Autonomic activation alters not only heart rate, conduction, and hemodynamics, but also cellular and subcellular properties of individual myocytes. The characterization of extrinsic cardiac ANS and intrinsic cardiac ANS ranges from the recognition of anatomic relationships at the gross level to discovery of chemoreceptors, mechanoreceptors, and intracardiac ganglia lining specific regions along the cardiac chambers and great vessels. Moreover, studies beginning >80 years ago [7][8][9] have demonstrated the critical role of cardiac ANS in cardiac arrhythmogenesis. This topic has garnered much recent interest because of mounting evidence showing that neural modulation either by ablation or stimulation can effectively control a wide spectrum of cardiac arrhythmias. [10][11][12][13] In this review, we will briefly discuss the anatomic aspects of cardiac ANS, focusing on how autonomic activities influence cardiac electrophysiology. We will also discuss specific autonomic triggers of various cardiac arrhythmias, including atrial fibrillation (AF), ventricular arrhythmias, and inherited arrhythmia syndromes. Lastly, we will discuss the latest avenues of research and clinical trials regarding the application of neural modulation in the treatment of specific cardiac arrhythmias.