There are four chambers in the heart: a right and left atrium (upper chambers), and a right and left ventricle (lower chambers). The atria usually pump blood into the ventricles at a regular rate, normally 60-100 times per minute. In atrial fibrillation (A-fib), however, the atria contract irregularly very fast, more like a quivering. This pumps blood less efficiently into the ventricles and can lead to blood clots in the heart and other problems.
Heart disease and other diseases can lead to atrial fibrillation. These include the following:
- Coronary artery disease (atherosclerosis, or narrowing of the blood vessels)
- Hypertension (high blood pressure)
- Heart valve problems, which lead to enlargement of the atria
- Congestive heart failure
- Hyperthyroidism (overactive thyroid gland)
- Lung diseases, like pneumonia, pulmonary embolism, and sarcoidosis
- Too much alcohol consumption
Signs and Symptoms
Tachycardia (heart rate > 100 beats per minute), palpitations, dizziness, lightheadedness, weakness, and shortness of breath. Atrial fibrillation may also cause no symptoms at all.
Patients may experience symptoms of a stroke, which include difficulty speaking or seeing, paralysis of a limb or body part, or loss of sensation of a specific area of the body.
Atrial fibrillation is diagnosed using an electrocardiogram (ECG or “EKG”), which detects the electrical activity of your heart. Your doctor may have you wear a Holter monitor, which detects the heart rate and rhythm for usually 24 hours, to detect atrial fibrillation and other arrhythmias that may come and go.
Your doctor will likely try to identify and treat the cause of your atrial fibrillation. To manage the atrial fibrillation, you will either receive medications or electrical cardioversion. Cardioversion is an electrical shock applied to your chest, approximately 200 to 300 Joules, that attempts to convert the atrial fibrillation to a normal “sinus” rhythm.
Instead of cardioversion, you may receive medications to achieve “rate control” and anticoagulation. Beta-blockers (metoprolol or atenolol), calcium channel-blockers (diltiazem or verapamil), and digoxin reduce the rate at which fast atrial fibrillation electrical impulses are transmitted to the ventricles. This reduces the pumping speed of the heart to a more normal 60-100 beats per minute and improves the heart’s efficiency at pumping blood.
In atrial fibrillation, blood clots can form in the atria since they are pumping blood less efficiently. These blood clots can travel to the brain, causing a stroke. To prevent clot formation, your doctor will also likely prescribe an “anticoagulant” like warfarin (brand name is Coumadin). While on Coumadin, you will have a periodic blood test to measure the International Normalized Ratio (INR), a test to determine your level of anticoagulation.
- Stroke (caused by blood clots originating from within the atria of the heart)
- Ischemia in the fingers or toes (from blood clots)
- Intestinal ischemia (from blood clots)
Some people are genetically more likely to develop atrial fibrillation. To reduce your risk, eat a healthy, low-fat diet; exercise; do not smoke; do not drink excessive amounts of alcohol; see your doctor regularly; and take medications exactly as prescribed.