London: A condition that temporarily causes heart failure among those who experience severe stress might actually protect the organ from very high adrenaline levels, says a research. The research provides the first physiological explanation for Takotsubo cardiomyopathy, also called "broken heart syndrome" because it affects people who suffer severe emotional stress after bereavement.

"Adrenaline's stimulatory effect on the heart is important for helping us get more oxygen around the body in stressful situations, but it can be damaging if it goes on for too long," said Sian Harding, professor at the National Heart and Lung Institute (NHLI) at Imperial College London, who led the study.

"In patients with Takotsubo cardiomyopathy, adrenaline works in a different way and shuts down the heart instead. This seems to protect the heart from being overstimulated," Harding was quoted as saying in the journal Circulation.

Around one to two percent of people who are initially suspected of having a heart attack are finally discovered to have this increasingly recognised syndrome, according to an university statement.

The study, which simulated the condition in a rat model, suggested that the body changes its response to adrenaline by switching from its usual role in stimulating the heart to reducing its pumping power.

Although this results in acute heart failure, most patients make a full recovery within days or weeks. The researchers propose that the switch in the heart's response to adrenaline might have evolved to protect the heart from being overstimulated by the particularly high doses of adrenaline that the body releases during stress.

Patients with Takotsubo cardiomyopathy, most often older women, experience symptoms that resemble a heart attack, but heart tests reveal no blockage in the coronary arteries; instead the heart has a balloon-like appearance caused by the bottom of the heart not contracting properly.

(Agencies)

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