What Are Cardiac Arrhythmias?
Cardiac arrhythmias are disturbances in the normal rhythm of the heartbeat. An occasional palpitation or fluttering is usually not serious, but a persistent arrhythmia may be life-threatening.
There are many different types of cardiac arrhythmias. The heart may beat too rapidly (tachycardia) or too slowly (bradycardia), or it may beat irregularly.
Atrial fibrillation and atrial flutter are common cardiac arrhythmias, which lead to an irregular and sometimes rapid heart rate. These atrial arrhythmias may interfere with the heart’s ability to pump blood properly from its upper chambers (atria). The atria may not always empty completely, and blood remaining there too long may stagnate and potentially clot. Such clots may travel to other parts of the body, where they may cause blockages in the blood supply to the limbs, brain, or heart.
In ventricular fibrillation, the lower chambers of the heart (ventricles) quiver feebly instead of contracting powerfully. This is the most severe type of arrhythmia, causing death in minutes unless medical assistance is obtained immediately.
What Causes Cardiac Arrhythmias?
- In some cases, the cause for arrhythmia is unknown.
- Arrhythmias may be present at birth (congenital).
- Disorders that damage the heart or its valves, such as heart disease, heart attack, endocarditis, myocarditis, myocardial ischemia (reduced blood flow to the heart), electrical conduction disorders and rheumatic fever may cause arrhythmia.
- Disorders of the thyroid gland
- Patients may develop an arrhythmia soon after chest- or heart-surgery.
- Dehydration or depletion of potassium or other electrolytes may trigger an arrhythmia.
- Some drugs, including digitalis, stimulants and diuretics, as well as overdoses of cocaine, marijuana, or antidepressants may provoke an arrhythmia.
- Injury to the heart due to a heart attack
- Risk increases with smoking, excess consumption of caffeine or alcohol, advancing age, high blood pressure, kidney disease, and stress.
- Other possible causes include aging, stress, caffeine, diet pills, alcohol and cough medication and smoking.
Symptoms of Cardiac Arrhythmias
- Palpitations or irregular-feeling heartbeats
- Shortness of breath
- Chest pain
- Dizziness, lightheadedness, and fainting
- Mental confusion
- Loss of consciousness
- In some cases there may be no symptoms
Prevention of Cardiac Arrhythmias
- Engage in regular aerobic exercise. Avoid cigarettes, illegal drugs, and excessive amounts of alcohol and caffeine. Try to reduce emotional stress.
- Carefully follow instructions for prescription drugs.
Diagnosis of Cardiac Arrhythmias
- Electrocardiography (ECG), to monitor the electrical impulses that control heartbeat; may require Holter monitoring (portable ECG) for a brief period (usually 24 hours)
- Blood pressure and blood tests
- Exercise (treadmill) stress test
- Chest x-rays and angiography (injection of a contrast material into an artery to produce a clear x-ray image of the blood vessels)
- Echocardiogram (use of ultrasound to map the heart’s movements and structure)
- An electrophysiologic study (a sophisticated electrical test of the heart involving electrical monitoring and stimulation inside the heart) may be performed
How Cardiac Arrhythmias Are Treated
- Sometimes, no treatment is required.
- Antiarrhythmic drugs (such as beta-blockers, calcium channel blockers, amiodarone, or procainamide) may be prescribed.
- Anticoagulants (such as aspirin or warfarin) may be prescribed to prevent the formation of blood clots, particularly for atrial arrhythmias.
- Digitalis (a drug that slows ventricular response to the rapid impulses coming from the atrium) may be prescribed for those with atrial arrhythmias.
- Defibrillation—a jolt of electricity applied to the chest by an emergency medical team—may restore normal heart rhythm if administered within a few minutes of the onset of ventricular fibrillation. An electric shock (cardioversion) may also be administered under nonemergent conditions to correct atrial arrhythmias.
- A pacemaker may be implanted in the chest if the heart rate is dangerously slow (called bradycardia).
- An ablation procedure (e.g., radiofrequency ablation) may be recommended to interrupt an abnormal electrical pathway. This can often be performed during an electrophysiologic study.
- Surgery may be done to interrupt an abnormal electrical pathway in the gheart, replace a damaged heart valve, or bypass blocked coronary arteries.
When to Call a Doctor
- EMERGENCY Call an ambulance if you experience severe chest pain, shortness of breath, or prolonged palpitations.
- EMERGENCY Call an ambulance if someone loses consciousness. If heartbeat or breathing has stopped, perform cardiopulmonary resuscitation (CPR).
Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference
Simeon Margolis, M.D., Ph.D., Medical Editor
Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50
Updated by Remedy Health Media