If I die because the plane goes into freefall, because a window or a door blows off, it will be because my heart is beating about 300 times a minute.
Severe turbulence throws off one’s breathing pattern and heartbeat races upwards. Best to take in deep breathes during the process. Surprised we don’t hear more stories re:, passengers thrown into cardiac arrhythmia’s during severe turbulent episodes.
I can understand someone's heart rate spiking as they assume they're experiencing their last few seconds. I certainly did.