Electrical neuromodulation improves myocardial perfusion and ameliorates refractory angina pectoris in patients with syndrome X: fad or future?

At present, there is no reliable antianginal drug therapy for patients with cardiac syndrome X. Therefore, the effect of electrical neuromodulation on refractory angina pectoris and myocardial perfusion in cardiac syndrome X was assessed. Eight patients (aged 55+/-7 years) with heterogeneous myocardial perfusion and no esophageal abnormalities were included. The subjects were nonresponders to antianginal drug therapy. Angina pectoris attacks and myocardial perfusion dynamics were evaluated by positron emission tomography at baseline and following 4 weeks of (transcutaneous electrical nerve stimulation) TENS. Following TENS there was a reduction of angina pectoris episodes (baseline 20+/-3, TENS 3+/-1; p=0.012), and short acting nitroglycerin intake per week (baseline 10+/-3, TENS 2+/-1; p=0.008). The rate pressure product (mmHg min(-1)) during the cold pressor test (CPT) was reduced during TENS (baseline 12800+/-1200, TENS 11500+/-900; p=0.02). Following TENS, the perfusion reserve ratio between rest and dipyridamole flow increased (baseline 1.59+/-0.15, TENS 1.90+/-0.11 ml min(-1)x 100g; p=0.05). The coronary vascular resistance had a trend towards a reduction (baseline 0.96+/-0.04, TENS 0.85+/-0.06 mmHg min(-1)x 100 g/ml; p=0.06) during CPT. This observation may suggest that neurostimulation improves angina pectoris with a concomitant improvement of myocardial perfusion in cardiac syndrome X.

Clinical follow-up after cessation of chronic electrical neuromodulation in patients with severe coronary artery disease: a prospective randomized controlled study on putative involvement of sympathetic activity.

The present study assessed the reoccurrence of myocardial ischemia after withholding electrical neurostimulation. After randomization, in the study or withdrawal group, spinal cord stimulation (SCS) was set active during the first 4 weeks, followed by 4 weeks of withholding stimulation. In the control group, SCS was switched off during 4 weeks before the end of the study. The control group had no crossover period. Measurements were done at baseline, then after 4 and 8 weeks. The first periods at 4 weeks of each sequence of both groups were compared. In addition, a comparison of clinical variables was performed between the study group 4 weeks after withholding stimulation and the control group 4 weeks following randomization. A total number of 24 patients with refractory angina and an implanted spinal cord stimulator were included in the study (n = 12) and control group. Angina pectoris complaints, nitroglycerin intake, ischemia, and heart rate variability using 48-hour ambulatory electrocardiographic monitoring were assessed. In addition, neurohormonal status and symptom-limited aerobic capacity were evaluated. There was no increase of anginal complaints or ischemia after withholding stimulation. Neurohormonal levels and aerobic capacity were not altered. We conclude that there is no adverse clinical rebound phenomenon after withholding neurostimulation in patients with refractory angina pectoris.

Coronary blood flow dynamics during transcutaneous electrical nerve stimulation for stable angina pectoris associated with severe narrowing of one major coronary artery.

To study the effect of transcutaneous electrical nerve stimulation (TENS) on coronary vasomotion, patients with New York Heart Association class III angina pectoris and significant single-vessel left coronary artery disease and who were also scheduled for elective percutaneous transluminal coronary angioplasty, were allocated to a study group (precordial actual TENS, n = 10) and a control group (precordial simulated TENS, n = 5, and TENS on the back, n = 3). Coronary volumetric flow was assessed in the stenotic and nonstenotic coronary artery before and after neurostimulation. The diameter (in millimeters) of the stenotic coronary artery was reduced in the study group after actual TENS (from 2.73 +/- 0.55 by 0.12 +/- 0.11; p = 0.008). In the nonstenotic coronary artery, the diameter increased in the study group (from 2.64 +/- 0.43 by 0.24 +/- 0.15; p = 0.01). In both the stenotic and nonstenotic coronary arteries, no effect was shown on the average peak velocity (centimeters per second) in the study group. The coronary volumetric flow (milliliters per minute) was reduced in the stenotic artery of the study group (from 62 +/- 18 by 8 +/- 7; p = 0.007). In the nonstenotic coronary artery, volumetric flow increased in the study group (from 57 +/- 18 by 11 +/- 10; p = 0.007). In the control group, simulated TENS and TENS on the back had no effect on the diameter of the artery, average peak velocity, or volumetric flow. In addition, in all patients, TENS had no effect on the total volumetric flow of the left coronary artery and hemodynamic variables during the study period. This observation suggests that TENS modulates regional coronary vasomotion in patients with coronary artery disease.

Sequelae of spinal cord stimulation for refractory angina pectoris. Reliability and safety profile of long-term clinical application.

BACKGROUND: Spinal cord stimulation (SCS) is effective in the treatment of severe coronary artery disease (CAD) unresponsive to anti-anginal medication or revascularization procedures. However, there is still concern about its safety. OBJECTIVE: To investigate the reliability, morbidity, and mortality aspects of SCS in patients with refractory angina pectoris by studying the predictors of outcome, defined by efficacy, adverse events and mortality, in patients with CAD and SCS. METHODS: Fifty-seven patients (18 women) treated with SCS, aged 59.8 +/- 7.6 years (mean +/- SD) were studied retrospectively. They had suffered from manifest CAD for 9.4 +/- 4.9 years; 46 of them had experienced a myocardial infarction prior to the implantation; 28 had had a previous percutaneous transluminal coronary angioplasty; and 52 had undergone coronary artery bypass surgery. The mean left ventricular ejection fraction was 51.8 +/- 13.8%. All of the patients were being treated with two or three anti-anginal drugs. RESULTS: During 2042 patient-months follow-up, nine of the 57 patients died (annual mortality rate 6.5%). The percentage of adverse events requiring reprogramming or surgical reintervention was reduced from 83% for 18 patients with the Medtronic ITREL lead to 33% for 39 patients with the ITREL II system. The clinical outcome was correlated positively with a left ventricular ejection fraction > 40% (P = 0.0005), and negatively with a high cholesterol level (P = 0.0042), more prior revascularizations (P = 0.028), and a higher New York Heart Association classification (P = 0.04). CONCLUSIONS: Improvement of the SCS system reduced the equipment-related complication rate. The predictors of outcome are related to the traditional risk factors for CAD. The mortality rate of patients with refractory angina treated with SCS is similar to that of patients with CAD and stable angina pectoris.