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Atrial fibrillation

Atrial fibrillation is an irregular and often fast heart rhythm originating in the upper chambers of the heart. It may cause palpitations and tiredness and increases the chance of clots and stroke.

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  • Atrial fibrillation is an irregular heart rhythm caused by chaotic electrical activity in the atria, the heart's upper chambers.
  • The heart rate may be fast, normal or sometimes slow. Some people feel palpitations; others notice little.
  • The condition is often not immediately life-threatening, but increases the chance of a clot and ischaemic stroke and may worsen heart failure.
  • An ECG is needed to record the rhythm. Sometimes longer rhythm monitoring is needed because episodes come and go.
  • Treatment focuses on preventing stroke, reducing symptoms, controlling heart rate and treating causes and risk factors.
  • Never stop rhythm, heart rate or anticoagulant medicines yourself. Protection against stroke may still be needed after a normal rhythm returns.

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PalpitationsPalpitations mean noticing your heartbeat as pounding, skipping beats, fluttering or suddenly speeding up. They are often harmless, for example because of stress, caffeine or an extra heartbeat, but sometimes a heart rhythm problem or another physical condition is responsible. Palpitations with fainting, chest pain, severe shortness of breath, becoming pale or weak, or an episode that does not settle need prompt assessment.
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Overactive thyroidWith an overactive thyroid, there is too much thyroid hormone in the body. Palpitations, weight loss, trembling and heat intolerance are common, but the cause must be established through blood tests; high fever, severe agitation and a very fast heart rate can indicate a rare thyroid storm.
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ThrombosisThrombosis is the formation of a blood clot in a blood vessel. A clot in a vein can cause, for example, deep vein thrombosis in the leg or a pulmonary embolism; a clot in an artery can cause a heart attack, stroke or acute blockage in an arm or leg. Symptoms and urgency depend on the location.