Guest Blog by Prof Sian Harding
Can you die of a broken heart? Even the poets seem undecided. Shakespeare said “the grief that does not speak whispers the o'erfraught heart and bids it break” but also “men have died’…and worms have eaten them, but not for love”.
Scientists, however, are true believers that love can break your heart. They have discovered not one, but two, diseases which deserve the name of Broken Heart Syndrome. But the twist is that one can kill you, while the other is trying to protect you. And it depends on whether you are a man or a woman.
The first one is a part of the syndrome of Sudden Cardiac Death or SCD. This happens when the heart goes into a state called ventricular fibrillation – instead of the whole heart contracting at the same time to eject blood, different parts of the heart start to beat out of time. The surgeons call the appearance of the heart the “bag of worms”. No blood is ejected, and so the body and brain quickly become starved of oxygen. The patient rapidly becomes unconscious and collapses, and death comes within a matter of minutes if there is no CPR or use of a defibrillator. SCD can be part of a heart attack but can also be triggered only by extreme physical or – crucially – emotional stress. Bereavement is a very strong trigger and can lead to SCD. The most striking fact is that you are statistically more likely to die in the period soon after your spouse or loved one. The period of risk peaks immediately after the event and the increased risk can be measured for about 6 months. Debbie Reynolds died the day after her daughter Carrie Fisher, and Johnny Cash died four months after his beloved wife June. The body reacts to this intense emotion in exactly the same way as to a physical threat to life, by release of adrenaline. While normal adrenaline levels are important to help you react to danger – the fight or flight response – extreme levels disrupt the regular electrical activity of the heart, to produce fibrillation.
Men are much more likely to succumb to SCD: about 80-90% of deaths from this syndrome are male. However, the second Broken Heart Syndrome (also called Takotsubo syndrome) is 80-90% female and is especially seen in older women after the menopause. Young women seem to be protected from both syndromes, interestingly. In Takotsubo, women present at the hospital with an apparent heart attack, and it very often follows a period of bereavement or emotional stress just like SCD. When their heart is imaged, it is found though that they are not having a heart attack, but that part of the heart is stunned and failing to beat. (This kind of imaging was first done on patients in Japan, and they thought the stunned heart looked like an octopus pot, or tako-tsubo, hence the name).
It can be very dangerous in the first few days, but the majority of patients recover and their heart function goes back to normal, or almost normal, in days to weeks. Once again, it is adrenaline that is having the initial effect but, in these patients, adrenaline switches to a different molecular pathway which shuts the heart down briefly to save it from fibrillation. If scientists try to block the Takotsubo pathways, then they can trigger SCD! This shows that Takotsubo is a relation of SCD, but much less deadly.
Why is this seen mainly in women, and then only in older ones? We know that estrogen can protect young women from the dangerous disturbances of heart rhythm caused by adrenaline. We think that older women, with decreasing estrogen, are moving from the fully protected state of younger women to the less protected state which is usual for men. Takotsubo syndrome is a kind of least-worst scenario, where the protective pathways are shutting down parts of the heart in an attempt to save them from something worse.
The big question is, why should young women be shielded from adrenaline? This we don’t know, but my hunch is that it is something to do with safeguarding the heart during the traumas of labour and birth. The adrenaline levels and blood pressure changes are extreme during the intense physical and emotional stresses here, which can continue for days. It would make sense for evolution to protect the mother during the important work of producing a baby. So even if women are more emotional, as is sometimes said, we can thank our biology for saving us from death by a broken heart!
Sian Harding is Professor of Cardiac Pharmacology at the National Heart and Lung Institute at Imperial College London, and Director of the Imperial Cardiac Regenerative Medicine Centre
The primary focus of her work has been cardiomyocyte function in the failing heart. This has extended to gene therapy to modulate cardiomyocyte function, and she was Scientific PI for the UK's first clinical trial on myocardial gene therapy. More recently the scope has extended to the characterisation of cardiomyocytes derived from embryonic stem cells, and their use in cardiac repair, tissue engineering and drug discovery.
Professor Harding is Past-President of the European Section of the International Society for Heart Research, is on the Board of the British Society for Gene and Cell Therapy and has been elected as a Fellow to the AHA, ESC and ISHR. She was Special Advisor to the House of Commons Science and Technology Select Committee on Regenerative Medicine and is now a member of the CGT Catapult: Pluripotent stem cells programme Advisory Panel.
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