Epidural spinal electrical stimulation for severe angina: a study of its effects on symptoms, exercise tolerance and degree of ischaemia

Abstract

The effectiveness of epidural spinal electrical stimulation has been studied in 14 patients with severe intractable angina unresponsive to standard therapies including bypass grafting. After implantation of the neurostimulator units the patients were assessed by a symptom questionnaire, treadmill exercise testing and right atrial pacing. There was a significant improvement of symptoms and GTN consumption fell markedly. With the neurostimulator on, exercise duration increased from a mean (CI) of 414 (153) to 478 (149) s, and total ST segment depression was less both at maximum exercise (7.1 (4.5) vs 5.6 (4.2) mm) and at 90% of the maximum control heart rate (3.5 (3.7) vs 2.6 (4.3) mm), with similar rate-pressure product at maximum exercise. With right atrial pacing the maximum heart rate reached before onset of angina was increased (143 (14) to 150 (7) b.min-1) and total ST segment depression was less at all heart rates. Benefit has persisted in some patients for over 2 years without any apparent adverse sequelae. Epidural spinal electrical stimulation is, therefore, an alternative therapy for some patients with intractable angina which has not responded to standard therapies.

Putative mechanisms behind effects of spinal cord stimulation on vascular diseases: A review of experimental studies

“…This population of neurons provides rapid and timely reflex coordination of autonomic neuronal outflow to the heart (Armour, 1999). Clinical observations show that SCS reduces the magnitude of ST segment changes in the electrocardiogram (ECG) induced by exercise and rapid cardiac pacing (Sanderson et al, 1992). SCS is considered to improve cardiac function to a considerable degree by regulating the intrinsic cardiac nervous system .…”

Electrical Neuromodulation and the Heart with Special Emphasis on Myocardial Ischemia

“…Later, several observational and randomized studies, making use of this expertise to evaluate antiischemic effects of SCS, by means of bicycle or treadmill exercise stress tests as the method of choice, show consistent findings of a reduction in ST-T segment depression at maximal and at comparable work load, in conjunction with improvement in exercise duration. 57,59,61,62,63 So, in spite of a prolonged exercise duration the patients had less myocardial ischemia. However, in a meta-analysis of 5 randomized studies on exercise stress tests ST-T segment changes were not significantly altered, following SCS (Fig 4) Some studies included in the meta-analysis used a subthreshold versus threshold stimulation, others used the design of stimulation versus no stimulation and others used stimulation versus active non-neurostimulation comparators.…”

“…Since the first publications, abundant articles have testified that electrical neuromodulation gained credentials in efficacy as an adjuvant therapy for in patients with severe refractory angina, irrespective of whether the method is applied at the skin of the chest, 42,43 cervically 55 at the T1-4 thoracic level, 56,57 or subcutaneously. 52,55 To assess the efficacy of electrical neuromodulation among patients with refractory angina receiving the various forms of electrical neuromodulation, comparative randomized control studies are warranted.…”

“…Many observational (long-term) studies on electrical neuromodulation have consistently observed a reduction in angina complaints and use of short acting nitrates 59,61,62, with a subsequent improvement in exercise capacity 59,60,61,62 and quality of life. 15,63,64 Quality of life measure, in this severely disabled group of patients, is usually executed by way of questionnaires (Nottingham health profile; Short Form-20 and RAND-36) and diaries (to score the daily number of angina attacks and number of NTG intake).…”

Effects of Spinal Cord Stimulation and Coronary Artery Bypass Grafting on Myocardial Ischemia and Heart Rate Variability: Further Results from the ESBY Study

“…Several studies have consistently reported a reduction of myocardial ischemia as measured by exercise test [1, 2, 3, 4], long-term ECG monitoring [5, 6], lactate metabolism [7]or stress echocardiography [8]. The Electrical Stimulation versus Coronary Artery Bypass Surgery (ESBY) Study [9]studied spinal cord stimulation as an alternative to coronary artery bypass grafting (CABG) in patients with no prognostic benefit from CABG and increased surgical risk.…”