Cardiac Arrhythmias
Disorders of the heart's electrical rhythm
Quick Facts
- Type: Heart rhythm (electrical) disorder
- Main types: Too fast, too slow, or irregular
- Common example: Atrial fibrillation
- Emergency signs: Fainting, chest pain, severe breathlessness
Overview
Cardiac arrhythmias are disorders of the heart's rhythm. Each normal heartbeat is triggered by an electrical signal that spreads through the heart in an orderly way. When that signal is generated abnormally, travels along the wrong path, or is blocked, the heart can beat too fast (tachycardia), too slow (bradycardia), or irregularly.
Arrhythmias range from harmless to life-threatening. Many people have occasional extra or skipped beats that are not dangerous. Others have sustained rhythm problems, such as atrial fibrillation, that raise the risk of stroke or heart failure, or dangerous fast rhythms from the lower chambers that can cause sudden collapse. Understanding which type is present, and what is causing it, guides treatment.
Symptoms
Some arrhythmias cause no symptoms and are found during a routine exam, while others produce noticeable effects:
- Palpitations, a fluttering, pounding, or racing sensation in the chest
- A feeling of skipped or extra beats
- Lightheadedness or dizziness
- Shortness of breath
- Chest discomfort
- Fatigue or reduced ability to exercise
- Fainting or near-fainting
Fainting, severe chest pain, or sudden severe shortness of breath with a very fast or very slow pulse can signal a dangerous arrhythmia and is a medical emergency. Collapse with no pulse requires calling emergency services and starting CPR.
Causes
Arrhythmias arise when the heart's electrical system malfunctions. Contributing factors and causes include:
- Heart disease: Coronary artery disease, previous heart attack, heart failure, and heart valve problems.
- High blood pressure and an enlarged or scarred heart.
- Electrolyte imbalances such as abnormal potassium or magnesium levels.
- Thyroid problems, particularly an overactive thyroid.
- Stimulants: Caffeine, alcohol, nicotine, certain medications, and illicit drugs.
- Inherited conditions affecting the heart's electrical channels.
Sometimes a clear cause is not found. Fever, infection, and stress can also temporarily provoke rhythm changes.
Risk Factors
- Coronary artery disease or a prior heart attack
- High blood pressure
- Heart failure or structural heart disease
- Diabetes and obstructive sleep apnea
- Overactive thyroid
- Heavy alcohol or caffeine use, and smoking
- Older age and a family history of arrhythmia
Diagnosis
Because arrhythmias can come and go, diagnosis often involves capturing the heart's rhythm over time:
- Electrocardiogram (ECG): Records the heart's electrical activity at that moment.
- Holter or event monitors: Wearable monitors record the rhythm over days to weeks to catch intermittent episodes.
- Echocardiogram: An ultrasound to assess the heart's structure and function.
- Blood tests: To check thyroid function and electrolytes.
- Stress testing or electrophysiology studies: Used in selected cases to provoke or map the arrhythmia.
Treatment
Treatment depends on the type of arrhythmia, symptoms, and risk:
- Lifestyle and trigger management: Reducing caffeine and alcohol, treating sleep apnea, and managing blood pressure.
- Medications: Drugs to control heart rate or rhythm, and blood thinners to prevent stroke in conditions like atrial fibrillation.
- Cardioversion: A controlled electrical shock to restore normal rhythm.
- Catheter ablation: A procedure that destroys small areas of tissue causing the abnormal rhythm.
- Pacemakers and implantable defibrillators (ICDs): Devices that regulate slow rhythms or correct dangerous fast ones.
Some arrhythmias need no treatment beyond reassurance, while others require ongoing care to prevent serious complications.
Prevention
- Control blood pressure, cholesterol, and diabetes
- Limit alcohol and caffeine and avoid stimulant drugs
- Do not smoke
- Stay physically active and maintain a healthy weight
- Get sleep apnea evaluated and treated if suspected
- Take prescribed heart medications consistently and attend follow-up appointments
When to See a Doctor
See a doctor if you have recurrent palpitations, an irregular pulse, dizziness, or unexplained fatigue. Call emergency services immediately for:
- Fainting or near-fainting with a racing or very slow heartbeat
- Chest pain or pressure
- Severe shortness of breath
- Someone who collapses and is unresponsive with no pulse, where CPR should be started
These can signal a life-threatening arrhythmia. Prompt treatment can be lifesaving.
Frequently Asked Questions
What is a cardiac arrhythmia?
It is a disorder of the heart's rhythm, where the heart beats too fast, too slow, or irregularly because of a problem with its electrical signals. Arrhythmias range from harmless extra beats to serious rhythms that can cause stroke, heart failure, or sudden collapse.
Are heart palpitations always serious?
No. Occasional skipped or extra beats are common and often harmless, especially when triggered by caffeine, stress, or lack of sleep. However, palpitations with fainting, chest pain, or severe breathlessness can signal a dangerous arrhythmia and need urgent medical attention.
What causes an irregular heartbeat?
Common causes include heart disease, high blood pressure, a prior heart attack, thyroid problems, and electrolyte imbalances. Caffeine, alcohol, nicotine, certain medications, and stress can also trigger arrhythmias. Sometimes no clear cause is found, and some types are inherited.
How are arrhythmias treated?
Treatment depends on the type and may include managing triggers, medications to control rate or rhythm, blood thinners to prevent stroke, electrical cardioversion, catheter ablation, or devices such as pacemakers and defibrillators. Some harmless arrhythmias need only reassurance and monitoring.
When is an irregular heartbeat an emergency?
Call emergency services if an irregular heartbeat comes with fainting, chest pain, or severe shortness of breath, or if someone collapses and is unresponsive with no pulse, in which case start CPR. These are signs of a potentially life-threatening arrhythmia.
References
- American Heart Association (AHA). Arrhythmia.
- National Heart, Lung, and Blood Institute (NHLBI). Arrhythmia.
- Mayo Clinic. Heart arrhythmia — Symptoms and causes.
- MedlinePlus, U.S. National Library of Medicine. Arrhythmia.