Reduced Heartbeat-Evoked Responses in a Near-Death Case Report

Abstract

Background and Purpose Whether brain–heart communication continues under ventricular fibrillation (VF) remains to be determined. There is weak evidence of physiological changes in cortical activity under VF. Moreover, brain–heart communication has not previously been studied in this condition. We aimed to measure parallel changes in heart-rate variability (HRV), cortical activity, and brain–heart interactions in a patient who experienced VF. Methods The EEG and EKG signals for the case report were acquired for approximately 20 h. We selected different 1-min-long segments based on the changes in the EKG waveform. We present the changes in heartbeat-evoked responses (HERs), HRV, and EEG power for each selected segment. Results The overall physiological activity appeared to deteriorate as VF proceeded. Brain– heart interactions measured using HERs disappeared, with a few aberrant amplitudes appearing occasionally. The parallel changes in EEG and HRV were not pronounced, suggesting the absence of bidirectional neural control. Conclusions Our measurements of brain–heart interactions suggested that the evolving VF impairs communication between the central and autonomic nervous systems. These results may support that reduced brain–heart interactions reflect loss of consciousness and deterioration in the overall health state.