Bradycardia is an abnormal heart rhythm condition. It happens when the heart beats at an unusually slow rate. It can be triggered by a number of health conditions, including hypothyroidism and hypothermia.
A normal heart rate is considered to be between 60 and 100 beats a minute (BPM). If your heart rate is less than 60 it is considered slower than normal. This can happen due to perfectly natural causes and may simply be a sign of being very fit. It can also occur in people in a state of deep relaxation. However, bradycardia can also be age-related, or a sign of a problem with the heart’s electrical system. If you are over age 65 you are more likely to experience bradycardia. It can also occur in people taking certain medication. Although it is more common in elderly people, bradycardia can also occur in children, especially after heart surgery.
Causes of bradycardia
Bradycardia can happen when:
- Changes occur in the heart due to ageing
- Certain diseases damage the heart’s electrical system, such as coronary heart disease, heart attack, diphtheria or myocarditis
- Certain conditions slow the normal electrical impulses in the heart, such as in hypothyroidism, or as a result of electrolyte imbalances, such as too much potassium in the blood
- Some heart drugs affect the heart’s rhythm such as beta blockers (including eye drops), and anti-arrhythmics
- Open-heart surgery has been performed.
Symptoms of bradycardia
Symptoms of bradycardia depend on how severe the condition is and which area of the heart is affected. Some people may experience no symptoms, or may attribute slight symptoms to ageing. Others may have symptoms such as:
Conditions associated with bradycardia include:
- Tachy-brady syndrome
- AV heart block
- Bundle branch block
Severe bradycardia can result in:
- Fainting and injuries caused by fainting
- Heart failiure
In some cases, severe bradycardia can be fatal.
Taking your pulse
If you think you have bradycardia, or you are concerned about your pulse, seek medical advice.
The British Heart Foundation recommends checking your pulse by following these steps:
- Use a clock or watch that has a second hand or digital display showing seconds
- Hold out one hand with palm facing up
- Place the pads of the first and middle fingers of your other hand on the inside of your wrist at the base of your thumb
- Press lightly and feel the pulse. If you can’t feel it, press slightly harder or move your fingers until you feel your pulse
- Count how many beats you can feel during 60 seconds
In order to diagnose bradycardia, your GP will:
- Do a physical examination
- Ask about your medical history
- Arrange an electrocardiogram, or ECG, to measure the electrical signals that control heart rhythm
As bradycardia can come and go, a standard ECG may not identify it. In that case, your GP may arrange a portable or ambulatory electrocardiogram. This is a lightweight device, also known as a cardiac event recorder. The device is worn for a day or two and records your heart rhythm during daily activities. Your GP may also arrange blood tests to find out if another problem is causing your bradycardia.