Causes and symptoms of arrhythmias
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What are the causes of arrhythmias?
There are various causes of arrhythmias. They include the following.
Heart conditions
Many arrhythmias occur as a complication of a heart condition. For example:
- Ischaemic heart disease (which causes angina and heart attacks). This reduces the blood supply to parts of the heart which may include parts of the conducting system. A damaged section of heart muscle (following a heart attack) can trigger an arrhythmia, or block electrical impulses.
- Heart valve diseases can cause the heart muscle to enlarge which can trigger abnormal electrical activity. For example, atrial fibrillation is a common complication of mitral valve disease.
- High blood pressure can put strain on the heart and cause arrhythmias.
- Age-related degeneration (ageing) around the conducting fibres is one cause of complete heart block.
- Cardiomyopathy (a disorder of the heart muscle) can sometimes cause arrhythmias.
- Some arrhythmias are due to abnormalities in the electrical pathways which are present from birth. One example is an extra electrical pathway which sometimes develops between the atria and ventricles. This can cause a type of SVT. (However, symptoms may not first start until you are a young adult.)
- Some congenital heart defects are associated with certain arrhythmias.
- Inflammation of the heart and other less common heart disorders are other possible causes.
Non-heart causes
Certain medicines and excess thyroid hormone can sometimes trigger an arrhythmia.
In some cases the cause is not clear
For example, some cases of atrial fibrillation and SVT occur 'out of the blue' in otherwise healthy hearts. A section of the conducting fibres just becomes faulty and can trigger fast impulses.
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