ABSTRACT
AIM: Spinal cord stimulation (SCS) is recommended for patients with coronary artery disease (CAD) and refractory angina. We used positron emission tomography (PET) to investigate the long-term effect of SCS on regional myocardial perfusion in patients suffering from angina pectoris refractory to medical treatment and without option for coronary intervention. PATIENTS, METHODS: We analyzed data of 44 patients with stable CAD (91% three vessel disease). At baseline, we determined coronary flow reserve (CFR) using 13N-ammonia-PET and myocardial viability with 18F-FDG. SCS was performed for one year (Medtronic Itrell III or Synergy, Düsseldorf, Germany). During follow-up, no cardiac interventions were necessary and no myocardial infarctions occurred. At one year follow-up, CFR was measured again. RESULTS: In the majority of patients (77%), SCS led to an improvement of clinical symptoms. CFR did not change significantly during follow-up. Subjective improvement did not correlate with an increase of CFR. CONCLUSIONS: Despite its clinical effect, SCS does not have a direct impact on CFR in patients with stable CAD. According to our results, the pain relief is not due to an improvement of the myocardial blood supply.
Subject(s)
Angina Pectoris/diagnostic imaging , Angina Pectoris/therapy , Coronary Circulation/physiology , Electric Stimulation Therapy/methods , Spinal Cord , Aged , Angina Pectoris/mortality , Blood Flow Velocity , Coronary Disease/diagnostic imaging , Coronary Disease/therapy , Follow-Up Studies , Humans , Middle Aged , Myocardial Ischemia/therapy , Positron-Emission Tomography , Retrospective Studies , Survival Analysis , Survivors , Ventricular Function, LeftABSTRACT
UNLABELLED: In both diabetic and nondiabetic patients, there is a loose correlation between coronary flow reserve (CFR) and sympathetic innervation in viable myocardial segments. The loose correlation implies that sympathetic innervation may be preserved even with major impairment of myocardial blood supply. In some patients, denervation is due to repetitive episodes of ischemia in areas with severely reduced CFR. We investigated the long-term effect of reduced CFR on myocardial sympathetic innervation in diabetic and nondiabetic patients with spinal cord stimulation. METHODS: We analyzed 23 patients (10 diabetic and 13 nondiabetic) with coronary artery disease and without known cardiac autonomic neuropathy. At baseline, we determined quantitative myocardial blood flow using (13)N-ammonia PET, myocardial viability using (18)F-FDG PET, and cardiac innervation using (11)C-hydroxyephedrine (HED) PET. At the 1-y follow-up we measured CFR and (11)C-HED retention. During follow-up, no cardiac intervention was performed and no myocardial infarction occurred. In all patients, spinal cord stimulation was performed for relief of angina. RESULTS: There was no significant difference in segmental (11)C-HED retention between baseline and follow-up in the whole patient group. In diabetic patients, as well as in segments with severely reduced CFR (<1.5), (11)C-HED retention showed a small but significant decrease (P<0.05). Linear regression of segmental (11)C-HED retention between baseline and follow-up was high (r(2)=0.81), confirming good reproducibility of the investigation on the one hand and little change in regional sympathetic innervation on the other hand. CONCLUSION: In patients with stable chronic coronary artery disease, sympathetic innervation of the myocardium is almost unchanged in both diabetic and nondiabetic patients in a 1-y follow-up. In myocardial segments with severely altered blood supply, a small but significant decrease in (11)C-HED retention most probably reflects ischemic neuronal damage. The prognostic relevance of sympathetic denervation in viable myocardium still has to be determined.
Subject(s)
Coronary Artery Disease/diagnostic imaging , Coronary Artery Disease/therapy , Electric Stimulation Therapy/methods , Heart/diagnostic imaging , Heart/innervation , Sympathetic Nervous System/diagnostic imaging , Female , Follow-Up Studies , Humans , Male , Middle Aged , Radionuclide Imaging , Treatment OutcomeABSTRACT
Clinical and histopathological findings hint at regional differences in the brain's sensitivity to metabolic changes in cirrhosis. The aim of the present study was to examine regional differences in cerebral ammonia metabolism in patients with cirrhosis and grade 0-to-I hepatic encephalopathy (HE). (13)N-ammonia, (15)O-water positron emission tomography (PET) and magnetic resonance imaging (MRI) were performed. Quantitative values of cerebral blood flow (CBF) and the initial cerebral ammonia uptake rate (K1) were derived for several regions of interest from images of the desired parameters after interactive coregistration with the patients' MRI-studies. CBF (mL/mL/min), K1 (mL/mL/min), and the ammonia extraction fraction (K1/CBF) showed marked regional variance with the highest levels in the thalamus, the lenticular nucleus, and the cerebellum. In conclusion, the regional differences in cerebral ammonia uptake correspond to the distribution of histopathological changes in the brain of patients with cirrhosis as well as clinical features of HE, characterized by signs of basal ganglia and cerebellar dysfunction with corresponding signs of functional impairment, especially of the frontal cortex and cingulate gyrus.