Sympathetic control of the heart

The sympathetic nervous system is responsible for the cardiac “fight-or-flight” response to stress and exercise. Its activation increases heart rate (positive chronotropy), cardiac contraction (positive inotropy), the speed of relaxation (positive lusiotropy), and conduction of the electrical signal through the heart (positive dromotropy). The cardiac sympathetic nervous system is largely opposed by the cardiac parasympathetic nervous system, yet in many primary cardiovascular diseases, emerging evidence suggests that disruption of the autonomic nervous system is a significant contributor to the etiology of heart disease itself. In the following chapter, we describe (1) the anatomy of the cardiac sympathetic nervous system, (2) how cardiac myocytes receive and respond to sympathetic stimulation, (3) the involvement of the sympathetic nervous system in cardiac pathophysiology, and (4) future perspectives and therapeutic opportunities.