An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm. The heart can beat too fast (tachycardia), too slow (bradycardia), or irregularly.
An arrhythmia can be harmless, a sign of other heart problems, or an immediate danger to your health.
Abnormal heart rhythms; Bradycardia; Tachycardia; Fibrillation
Normally, your heart works as a pump that brings blood to the lungs and the rest of the body.
To help this happen, your heart has an electrical system that makes sure it contracts (squeezes) in an orderly way.
- The electrical impulse that signals your heart to contract begins in an area of the heart called the sinoatrial node (also called the sinus node or SA node). This is your heart's natural pacemaker.
- The signal leaves the SA node and travels through the heart along a set electrical pathway.
- Different nerve messages signal your heart to beat slower or faster.
Arrhythmias are caused by problems with the heart's electrical conduction system.
- Abnormal (extra) signals may occur.
- Electrical signals may be blocked or slowed.
- Electrical signals travel in new or different pathways through the heart.
Some common causes of abnormal heartbeats are:
- Abnormal levels of potassium or other substances in the body
- Heart attack, or a damaged heart muscle from a past heart attack
- Heart disease that is present at birth (congenital)
- Heart failure or an enlarged heart
- Overactive thyroid gland
Arrhythmias may also be caused by some substances or drugs, including:
- Alcohol, caffeine, or stimulant drugs
- Heart or blood pressure medicines
- Cigarette smoking (nicotine)
- Drugs that mimic the activity of your nervous system
- Medicines used for depression or psychosis
Sometimes medicines used to treat one type of arrhythmia will cause another type of abnormal heart rhythm.
Some of the more common abnormal heart rhythms are: