What happens with stress, if there's distraction before a story reaches it's end? I remember reading of a study where children were told stories. During the telling of the story tension rose and the heart rate increased. After the story was over the heart rate went back to normal.

There was another experiment where the story wasn't told to the end. During the telling of the story, attention shifted elsewhere while the tension was still up and the story never reached its end. In that condition, the heart rate stayed elevated.

Unfortunately, I don't remember the exact source. Can you tell me whether the described effect exists and if so, point me to the studies about it?
When stress is chronic it could provoke bad effects:


High blood pressure
Impaired cognition (maybe it explains the distraction) 
Lowered immune system


In my opinion, the distraction could be the effect of the increased level of cortisol... I wish my intervention will be useful.

REFERENCES
Michael S. Gazzaniga, Richard B. Ivry, George R. Mangun (2013),  "Cognitive Neuroscience: The Biology of the Mind: 4th Edition"