What is BRADYCARDIA?
Bradycardia is when the heart rate has slowed down to less than 55 beats per minute.
Why does this happen and how may it affect the patient’s health?
Most commonly occurs in athletes as the result of training because of increased tone from the Vagus nerve (tenth cranial nerve).
May be due to abnormalities of the conducting system of the heart, such as complete heart block.
Certain systemic diseases may give rise to bradycardia such as
- Typhoid fever (infection caused by micro-organism, Salmonella typhi)
- Brucellosis (infection passed on to humans by animals)
- Hypothyroidism (myxoedema; underactive thyroid gland)
- Advanced liver disease
- Acute high blood pressure
Certain pharmacological products such as
- Phenylpropanolamine
- Beta-blockers (drugs that slow heart rate)
- Calcium channel blockers
- Digitalis overdose
- Lithium
Other conditions include
- Hypothermia (low body temperature)
- Increased intracranial pressure (brain swelling or bleeding inside skull)
- Severe lack of oxygen
- Sick sinus syndrome (SA node, the primary pacemaker of the heart, does not function correctly)
What symptoms may the patient experience?
There are usually no symptoms, but a patient may present with
- A slow heart rate
- Fainting (elderly patients)
- Stokes-Adams syncope (fainting attacks; a condition known to cause bradycardia)
- Intermittent dizziness
- Loss of consciousness
How is the diagnosis made and what special investigations are required?
- ECG
- Ambulatory ECG (patient walks and sleeps with ECG strapped to body for 24 hours)
What is the treatment?
No treatment is required
- If there are no symptoms, or
- When there are no underlying causes for concern
Treatment of heart block: As a temporary measure, medications that stimulate the sympathetic nervous system are administered.
Patients who experience symptoms due to bradycardia (slow heart rate) require a pacemaker.
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