Electrical stimulation of dorsal segments of the spinal cord has been used to treat patients with severe angina pectoris that is refractory to conventional therapies. The concept is based on the “gate control theory” first proposed by Melzack and Wall, in which a neuronal “gate” in the dorsal horn of the spinal cord controls the flow of noxious stimuli to the brain. Thus, spinal cord stimulation (SCS) can be thought of as “closing the gate” on pain. In the most often-used technique, an electrode is inserted over the dorsal columns and placed in the segments where electrical stimulation elicits paresthesias in the painful dermatomes. SCS activates large afferent fibers that have the ability to suppress stimuli from small fibers transmitting nociceptive information, and thereby “closes the pain gate.”
This article will briefly review the efficacy of SCS in relieving angina pectoris, provide an overview of the spinal processing of cardiac nociceptive information and the neural mechanisms of referred pain in the thoracic and cervical spinal cord, and examine the effects of SCS on the heart.