Visualization of Catastrophe of Autonomic-Nerve Systems after Great Eastern-Japan Earthquake Struck on Mar. 11, 2011

Abstract

Background: Little is known about autonomic nerve mechanisms just before onset of life-threatening cardiovascular events. Very few attempts have been made at dissection of dynamic alteration of autonomic tone when we get into a panic. Purpose: We examined the dynamic alteration of autonomic-nerve tone just before and after Great Eastern-Japan Earthquake struck on Mar. 11, 2011 by using new analyzed method for heart rate variability (HRV). Methods: Three patients (male:female=2:1) were selected for this study, of whom sinus rhythm was documented in Holter electrocardiogram on that day. HRV was analyzed by the maximum entropy method (MemCalc/CHIRAM, Suwa Trust Japan). This method enabled us to achieve a reliable analysis of HRV component at 10 second intervals for 30 second periods from 30 minutes before earthquake. The high frequency band (HF: 0.15–0.4 Hz), the low frequency band (LF: 0.04–0.15 Hz), and the very low frequency band (VLF: 0.003–0.04 Hz) were measured. Results: HRV tended to show normal circadian fluctuation before the earthquake; however, unexpected suppression of both HF and LF/HF were simultaneously seen just after abrupt earthquake. In contrast, remarkable sinus tachycardia was seen in all patients. Soon after that, HF suppression and surge of LF/HF were sustained for a while under continued stress of aftershock activity. Conclusions: There is a fair possibility that we can put the MemCalc method to observe catastrophe of autonomic-nerve systems after big stress such as the greatest earthquake on record.