Spinal cord injury alters cardiac electrophysiology and increases the susceptibility to ventricular arrhythmias.

The autonomic nervous system modulates cardiac electrophysiology and abnormalities of autonomic function are known to increase the risk of ventricular arrhythmias. The abnormal and unstable autonomic control of the cardiovascular system following spinal cord injury also is well known. For example, individuals with mid-thoracic spinal cord injury have elevated resting heart rates, increased blood pressure variability, episodic bouts of life-threatening hypertension as part of a condition termed autonomic dysreflexia, and elevated sympathetic activity above the level of the lesion. Furthermore, cardiovascular morbidity and mortality are high in individuals with spinal cord injuries due to a relatively sedentary lifestyle and higher prevalence of other cardiovascular risk factors, including obesity and diabetes. Therefore, spinal cord injury may alter cardiac electrophysiology and increase the risk for ventricular arrhythmias. In this chapter, we discuss how the autonomic changes associated with cord injury can influence cardiac electrophysiology and the susceptibility to ventricular arrhythmias.