Watching stressful films can endanger weak hearts
Watching a stressful film can make the heart less stable and increase blood pressure, says a study from University College London and Guy's and St. Thomas' Hospital.
The changes were not likely to put healthy people at risk, but could be dangerous in those with weakened hearts, researchers said.
Nineteen patients were monitored while watching a clip of Vertical Limit.
The heart changes are thought to be linked to the autonomic nervous system.
It was the first time the biological effects of mental and emotional stress had been recorded in healthy conscious patients, the research team said.
Stress and emotion have previously been to linked to changes in heart rhythms and to sudden death in humans.
In this small study, published in the journal Circulation, Arrhythmia and Electrophysiology, researchers looked at the effect of a stressful film clip on blood pressure, heart rhythm and breathing speed in a group of adult patients undergoing routine cardiac treatments.
The film clip lasted nearly five minutes and showed a dramatic rock-climbing accident.
The changes were monitored using electrodes placed in the ventricles of the heart.
Their results showed watching the film affected the rhythm of the heart, making it less stable.
The patients' respiration rate was also found to increase during the stressful part of the film clip by two breaths per minute.
Study author Dr Ben Hanson, from the department of mechanical engineering at University College London, said the findings helped their understanding of the impact mental and emotional stress could have on the human heart.
"This is the first time that the effects have been directly measured and although the results varied from person to person we consistently saw changes in the cardiac muscle," he said.
"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."
Nervous system role
When the patients were asked to reproduce the breathing pattern they experienced during the film at another time, researchers found that changes in the heart muscle did not occur.
This suggested that the effect of the stressful film on the heart was not related to a change in breathing, but a direct effect of the autonomic nervous system and the impact of the viewing, they said.
Prof Peter Taggart, joint study author, from the neurocardiology unit at University College London Hospitals, said film clips were a very powerful stimuli because of their "dynamic nature, sustained effect and the combination of visual and auditory inputs".
Watching the World Cup this summer may not be good for people with a heart condition since there had been shown to be a spike in hospital admissions, which could be "tied down to stressful quarter-final time", Dr Hanson added.