Watching films which include stressful scenes can trigger changes to the pattern of heartbeats, new research has revealed.
A study has found that although changes in the heart while watching an emotionally charged film clip were small and not likely to be a risk to normally healthy people, they did result in a disturbance to the normal heartbeat and a significant increase in blood pressure.
The researchers said this could have consequences for patients who already had a weakened heart, or for those exposed to extremely stressful situations.
The study focused on a group of 19 patients who were already undergoing investigation and treatment for minor heart- rhythm problems but did not have heart disease.
The patients had cardiac catheterisation using local anaesthetic, where a line is inserted near the groin and passed through the blood vessels to the heart, aided by X-ray. The researchers also placed electrodes in the ventricles of the heart to measure changes in the cardiac muscle, while the team simultaneously recorded changes to blood pressure and breathing speed.
The volunteers were then shown a clip from the 2000 film Vertical Limit, starring Chris O’Donnell, the tagline to which is “Hold your breath”. The clip included a dramatic scene in which a group of climbers are shown hanging off the side of a steep cliff, before several of them fall to their deaths.
The researchers, from University College London, King’s College London and Guy’s and St Thomas’ Hospital, observed changes to the heart muscle in the patients during the scenes.
They said the new method used in the study meant that, for the first time, the biological effects of mental and emotional stress had been recorded in healthy, conscious patients.
Researcher Dr Ben Hanson, from University College London, said: “Our findings help us to better understand the impact mental and emotional stress can have on the human heart.
“This is the first time the effects have been directly measured and although the results varied from person to person, we consistently saw changes in the cardiac muscle. If someone already has a weakened heart, or if they experience a much more extreme stress, the effect could be much more destabilising and dangerous.”
Explaining why they chose to use film clips, study author Professor Peter Taggart added: “Film clips are considered to be among the most powerful stimuli to elicit affective responses in the laboratory setting.”
In a part of the study related to breathing patterns while viewing the clip, researchers said neither blood pressure nor heartbeat were altered by replicating those patterns, suggesting changes in breathing brought on by a shock do not trigger the observed changes in heartbeat.
The researchers said they suspected this showed that exposure to a stressful situation increased activity of the body’s “sympathetic nerve”, which impacted on the heart.