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Body responds to high dose of stress in unique way

A condition that temporarily causes heart failure in people who experience severe stress might actually protect the heart from very high levels of adrenaline, according to a new study published in the journal Circulation.

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, and suggests guidance for treatment.

Around 1-2% of people who are initially suspected of having a heart attack are finally discovered to have this increasingly recognized syndrome.

The Imperial College London study, which simulated the condition in an animal model, suggests 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. The same condition is sometimes seen in people who are injected with adrenaline to treat severe allergic reactions.

Protection of Heart

"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," Professor Sian Harding, from the National Heart and Lung Institute (NHLI) at Imperial College London, who led the study was quoted in Science Daily.

 "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."

Dr Shannon Amoils, Research Advisor at the BHF, said: "This is a fascinating study which presents a possible explanation for the signs of Takotsubo cardiomyopathy, a rare condition that's usually preceded by intense emotional or physical stress. Patients usually have symptoms that resemble those of a heart attack but nearly all fully recover after a short time.

"The study also provides new insights into how the heart may protect itself from stress, which opens up exciting avenues of exploration for research. We must remember though that this is a study in rats, and the findings need to be confirmed in people before we can be sure of their relevance to patients."