Spinal cord stimulation for chronic intractable angina pectoris: A unified theory on its mechanism

Abstract

Summary:The use of spinal cord stimulation (SCS) for chronic intractable anginal pain was first described in 1987. Numerous studies have demonstrated its efficacy in improving exercise tolerance, decreasing frequency of anginal episodes, and prolonging time to electrocardiographic signs of ischemia.This review will examine the potential mechanisms of this antianginal effect and propose a unified hypothesis explaining it. The effect of SCS involves a mutual interaction of decreased pain, decreased sympathetic tone, and a likely redistribution of myocardial blood flow to ischemic regions. Spinal cord stimulation reduces the transmission of nociceptive impulse via the spinothalamic tract due to an enhanced release of gamma aminobutyric acid (GABA) from dorsal hom intemeurons. Improvement of myocardial blood flow at the microvascular level has been demonstrated by positron emission tomography (PET). A decreased sympathetic tone has been shown by norepinephrine kinetics, tests of sympathetic reflexes, and the use of ganglionic blockers. We hypothesize that SCS exerts its beneficial effects by decreasing pain and decreasing sympathetic tone, the result of which is decreaqed myocardial oxygen consumption along with an improved myocardial microcirculatory blood flow.

Myocardial Sympathetic Innervation in Patients with Symptomatic Coronary Artery Disease: Follow-up After 1 Year with Neurostimulation

“…Our data do not support this thesis, as blood flow under rest and stress conditions, as well as CFR, did not change significantly (Table 2). Another hypothesis is that SCS reduces sympathetic tone, decreasing myocardial oxygen consumption and improving myocardial microcirculatory blood flow (26,28). We cannot rule out the possibility that the assumed reduction in sympathetic tone leads to a protective effect on the sympathetic neurons themselves, causing the neurons to be less susceptible to ischemic damage.…”

Cost-Effectiveness of Spinal Cord Stimulation versus Coronary Artery Bypass Grafting in Patients with Severe Angina Pectoris – Long-Term Results from the ESBY Study

“…Earlier studies have indicated that myocardial ischemia is reduced by SCS, which in turn seems to be due to a reduction in oxygen consumption, and that the treatment does not deprive the patient of a warning signal [1, 3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]. …”

Comparison of patients undergoing enhanced external counterpulsation and spinal cord stimulation for refractory angina pectoris

“…It is proposed that SCS affects the balance between myocardial oxygen supply and demand by recruitment of collaterals and increases angiogenesis. Beneficial effect on pain relief and on sympathetic tone is observed; this yields reduction in pain and oxygen consumption in the heart [20]. The final pathways for the effects of SCS are the intracardiac neurons [6].…”

“…SCS has been found to be an effective treatment, although the mechanism of action is complex and not fully elucidated [3,6,19,20]. It is proposed that SCS affects the balance between myocardial oxygen supply and demand by recruitment of collaterals and increases angiogenesis.…”