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Heart Arrhythmias

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What is Heart Arrhythmia?

Heart arrhythmia (ay-RITH-me-ah) is when your heartbeat is irregular or out of rhythm. This might mean a fast heartbeat, a very slow heartbeat, or “palpitations” (where your heart beats very hard, fast, or irregularly for a short period of time).

What causes heart arrhythmia?

This can be caused by:

  • Heart conditions such as heart failure, angina, or congenital heart illness
  • A heart attack in the past, which can cause damage to the heart muscle
  • Long Covid may cause palpitations or arrhythmia
  • Stroke can cause changes in your heart’s rhythm
  • Anxiety and other mental health problems
  • Medication or drug use

The impact of heart rate changes can vary a lot. Some people may not even know that anything is wrong with their heartbeat, while other people may experience pain, discomfort, dizziness, breathlessness, and/or anxiety as a result of the changes in heart rate.

Normal heartbeat

To understand changes in heartbeat and heart rate, you have to first know what is normal.

The human heart on average beats between 60 and 100 times per minute, when the person is at rest (i.e. not doing anything to increase their heart rate). Exercise or stress (such as fear or anxiety) can raise that heart rate to around 150-170 beats per minute.

Your heartbeat comes in two stages. These are the systolic phase (when the heart is filling up with blood) and the diastolic phase (when the heart contracts, pushing the blood around the body).

Under normal circumstances, your heart beats slightly harder when you are standing up, compared to when you are lying down, because the blood needs to be under more pressure to reach your head and upper body.

Fast heart rate

An unusually high heart rate (more than 100 beats per minute at rest) is called tachycardia (tacky-card-ee-ah).

Because the heart is beating faster, it does not have as much time to fill with blood. As a result, a fast-beating heart actually moves blood less efficiently. This can mean that if you have a consistently high heart rate, parts of your body may struggle to get enough blood flow and the oxygen and nutrients that are carried in the blood. In extreme cases, you may feel dizzy, light-headed, or breathless, as the blood struggles to reach the upper parts of your body.

Because a fast heart rate is a natural part of your body’s stress response, your body may also interpret a fast heartbeat as a sign that something is wrong. This can make you feel anxious or fearful, even without a clear cause.

A fast heartbeat also puts your heart muscles under extra pressure. This can increase the risk of heart complications like angina, heart failure, or heart attack.

Tachycardia can be treated by:

  • Addressing any underlying conditions, like high or low blood pressure, PoTS, or lung conditions.
  • Targeting the vagal nerve, a big nerve which helps to regulate the heartbeat.
  • Certain medications (only take these if prescribed by a doctor)

Slow heart rate

A slow heart rate (less than 60 beats per minute) is called bradycardia (bray-dee-car-dee-ah). It can be caused by certain medications, or by heart conditions like sick sinus syndrome or myocarditis.

The slow heartbeat means that less blood is transported around the body. This can cause dizziness, chest pain, fatigue and tiredness, breathlessness, fainting, and confusion or memory problems. People with a slow heartbeat may also find they suffer from a low mood or find it hard to think clearly.

Bradycardia can be treated by:

  • Addressing any underlying conditions or causes (e.g. changing your medication if it causes your heart rate to slow)
  • Regular, careful exercise and a good diet

Heart palpitations

Heart palpitations are when your heartbeat becomes noticeable. It may be harder, faster, or less regular than usual. You may feel fluttering, pounding, or vibrating sensations in your chest. In some cases, you may also feel these sensations in your throat and neck.

Palpitations don’t last long – usually no more than a few minutes – and are usually harmless.

They do not necessarily mean anything is wrong with you. Palpitations can be caused by stress or anxiety; by caffeine and other stimulants like sugar; or as a side effect of some medications. They can be frightening, but they should pass on their own. If you are having palpitations, try to relax and focus on your breathing until they pass. You should speak to a doctor or other health professional if you think that you are having heart palpitations, but it is not an emergency.

While palpitations are usually not an emergency, you should call 999 if your palpitations are causing dizziness, breathlessness, or chest pain lasting more than five minutes.

This page was last updated on July 21, 2022 and is under regular review. If you feel anything is missing or incorrect, please contact to provide feedback.

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