Heart rate variability, norepinephrine and ECG changes in subarachnoid hemorrhage patients

While electrocardiographic abnormalities in subarachnoid hemorrhage patients have been known since 1947, the provocative mechanism has not yet been satisfactorily explained. The purpose of this study was to evaluate with some tests, the role of autonomic nervous system in provoking the electrocardiographic abnormalities in 22 patients with subarachnoid hemorrhage. The standard electrocardiographic tracings and one-channel computer-based electrocardiographic tracings for spectral analysis of heart rate variability were made. Blood samples for plasma norepinephrine concentrations were taken. Statistically significant parasympathetic hyperactivation between Days 4 and 6 after sudden onset of the disease was found. In standard electrocardiographic tracings in almost all patients transient repolarisation changes and in one patient transient premature ventricular complexes were observed. Plasma norepinephrine concentrations did not parallel electrocardiographic abnormalities. No statistically significant correlation was found among tests of autonomic nervous system activity. Electrocardiographic abnormalities in our group of patients were transient, functional and observed only in the acute phase. They were probably not dependent on elevated plasma norepinephrine concentration. Spectral analysis of heart rate variability failed to explain the role of the autonomic nervous system in provoking the cardiac abnormalities.