Oestrogen hormone could be behind arrhythmia in women according to researchers
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The sex hormone oestrogen could be a contributing factor behind why more women than men suffer from arrhythmia. While women generally have a lower chance of developing cardiovascular diseases, this is not the case when it comes to hereditary diseases that cause abnormal and irregular heart rhythm.
Researchers at the University of Linkoping in Sweden have looked at one particular disease known as Long QT syndrome (LQTS), which increases the time it takes for the heart to finish every heartbeat. LQTS is most often due to congenital hereditary changes, or mutations, which affects one of the heart’s ion channels, but is rare and only affects one in 2,500 people.
Ion channels are small pores that go through a cell’s membrane and regulate the flow of electrically charged ions going in and out of the cell. Some of these channels act as accelerators and others as brakes, and together they regulate every one of the around 2.5 billion heartbeats most humans have during our lifetime.
Author Sara Liin, associate professor in the Department of Biomedical and Clinical Sciences said: “We’re trying to understand which substances in the body impact the function of the ion channels. If we could figure out how this regulation works, maybe we can understand why some individuals are more protected and others are hit harder.”
The research team inserted the human variant of the ion channel into frogs’ eggs, which normally don’t have the channel. They then added the most active form of the sex hormone oestrogen, known as estradiol, and measured the function of the ion channels.
The results showed that ion channel function was hampered by the oestrogen, which shows that the hormone may increase the risk of certain types of arrhythmia, and no other sex hormones had any effect. The research, published in Science Advances, went on to discover exactly which parts of the channel were affected by the sex hormone.
Further examination into ion channel mutations found in families with hereditary arrhythmia syndromes found that some mutations led to high oestrogen sensitivity. They also found that some mutations led to the ion channel completely losing oestrogen sensitivity.
Prof Liin said: "We show that some hereditary mutations that reduce ion channel function seem to contribute to high oestrogen sensitivity, so there could be two risk factors that interact especially in women carriers of these mutations. We believe that our study gives good reason to look closer at this in patients."
Liin and her colleagues point out that while women with hereditary increased risk of LQTS, oestrogen could possibly be a risk factor, there are many positive effects of the hormone.