Heartbeat interval dynamics in response to acute stress in human: A case study of real fear of snake

Heartbeat dynamics changes promptly and substantially in response to acute stress. This is due to direct neural connection of the heart and the central nervous system. An opportunity to analyze a video recording synchronized to a simultaneously recorded ECG arose after preparation of educational TV show about adrenaline. Although the scenario for the experiment in Ljubljana Zoo did not presume to expose a person to acute fear, the unexpected situation of awareness of proximity of the snake's head led to actual sudden acute fear of the snake for the third time in person's life. This case study presents heartbeat dynamics before and during acute fear phase. The response of the heart to acute fear was immediate. Large and fast variations of heartbeat intervals were observed throughout the whole experiment (heartrate decrease by up to 32 beats/min in 5 seconds), indicating upheaval in regulation of cardiovascular parameters.