Researchers of the University College in London have discovered that the system which normally coordinates signalling from the brain to different parts of the heart may be disrupted in some people, making them vulnerable to potentially fatal abnormal heart rhythms during mentally taxing tasks or emotional events.

Mental stress is thought to be responsible for a further 20 per cent of sudden cardiac deaths, but scientists have been baffled by the exact mechanisms by which stress can bring on a fatal short-circuiting of the heart. The new study suggests that uneven brain activity in the brainstem seems to result in an uneven distribution of signals across the heart, which stops the heart from contracting normally.

In the UCL study, volunteers with a history of heart disease were given stressful mental tasks while their brain activity was monitored using PET imaging. Electrical waves travelling across their heart were monitored using electrocardiogram analysis.

The study showed that stress-induced changes in electrical currents in the heart were accompanied by uneven activity within the brainstem which is connected on the left and right side to the heart by nerve pathways. UCL scientists think that, in some cases, these autonomic nerves fire unevenly during stress, which disturbs the smooth electrical pattern across the heart and could ultimately induce an irregular, and eventually fatal, heartbeat.

"The combination of heart and brain irregularities means that heart failure could occur during a stressful or emotional event like a family gathering or even a boisterous New Year party,” concludes Dr Peter Taggart from UCL`s Centre for Cardiology.

"Our research focuses on what is happening upstream, in the brain, when stress causes these heart rhythm problems. It may soon be possible to identify which people are particularly at risk and even to treat a heart problem with a drug that works on the brain,” Taggart says.

MEDICA.de; Source: University College, London (UCL)