How broken heart syndrome PROTECTS the grief-stricken from dying
Around two per cent of people thought to have had a heart attack are diagnosed with the syndromeIt gives the heart a 'balloon-like' appearance but symptoms go after two weeks
13:10 GMT, 27 June 2012
13:13 GMT, 27 June 2012
People who suffer from intense grief after the death of a loved one are often said to be at risk of dying from a broken heart after developing symptoms of cardiac arrest.
But scientists studying ‘broken heart syndrome’ have found the condition may actually have a protective purpose by stopping the organ being pumped with too much adrenaline.
Around one or two per cent of people who are initially thought to have suffered a heart attack are diagnosed with the syndrome, also known as Takotsubo cardiomyopathy.
'Broken heart' syndrome most often affects grieving older women
Patients – mostly older women – experience symptoms that resemble a heart attack, but 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.
The Imperial College London study on rats suggests 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 believe this switch might have evolved to protect the heart from being overstimulated by the particularly high doses of adrenaline the body releases during stress.
Professor Sian Harding said: '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.
'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.'
Researchers simulated the condition by injecting high doses of adrenaline in anaesthetised rats – heart muscle contraction was suppressed towards the bottom of the heart, as in Takotsubo patients.
Results showed the rats were protected from a fatal overstimulation of the heart – suggesting adrenaline acts through a different pathway than usual, with this switch protecting the heart from toxic levels of adrenaline.
The study also examined drugs that might be useful for treating broken heart syndrome – finding some beta blockers used to treat high blood pressure, angina and heart failure, reproduced or enhanced features of Takotsubo – giving new insights into the protective effects of these drugs.
They also found Levosimendan, a different type of drug given in heart failure to stimulate the heart without going through the adrenaline receptor pathways, had a beneficial effect.
Dr Alexander Lyon, also of Imperial College London, said: 'Currently it is not fully known how to treat these patients. Insights from this work show that the illness may be protecting them from more serious harm.
'We’ve identified a drug treatment that might be helpful, but the most important thing is to recognise the condition, and not to make it worse by giving patients with Takotsubo cardiomyopathy more adrenaline or adrenaline-like medications.
'We hope the findings from this work will lead to new treatment strategies for these patients during the acute phase of their illness, and to prevent recurrence.'
The study was funded by the British Heart Foundation (BHF), the Wellcome Trust, the Biotechnology and Biological Sciences Research Council (BBSRC) and the Academy of Medical Sciences.
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.'
The study was published in the journal Circulation.