Spinal cord stimulation in refractory angina pectoris--clinical results and mechanisms.

Patients with therapeutically refractory angina pectoris do not respond to adequate anti-anginal medication and are not suitable anymore for revascularisation procedures. This group of patients has a poor quality of life, since their exercise capacity is severely afflicted. A new additional therapy for patients with refractory angina is neurostimulation. The concept of neurostimulation is based on the "gate control theory", a model in which nociceptive unmyelinated fiber afferents (C and A delta) are inhibited by non-nociceptive myelinated fiber afferents. Patients treated with spinal cord stimulation (SCS) show an increase in exercise capacity and a concomitant reduction in myocardial ischemia. A reduction in anginal attacks and nitroglycerin intake is also reported. The mechanisms of action of SCS are unclear, although there is evidence of an increase in myocardial oxygen supply, as is shown in peripheral vascular disease. Sympathetic nervous activity, prostaglandins, and endogenous opiates may also play a role in pain suppression by SCS. As soon as the safety and the complication rate are established, SCS may be commonly used as an additional therapy in patients with so-called "intractable angina pectoris".