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What is Atrial Fibrillation?
Atrial Fibrillation, commonly called A Fib occurs when the heart's electrical conduction system doesn't work properly. The heart beats because of an electrical stimulus initiated by the sinoatrial node, located above the atria. The atria are the top two chambers of the heart. This signal travels down and causes the atria to contract, pushing blood to the ventricles, or bottom two heart chambers.
When A Fib causes the electrical signal to misfire, the atria quiver very quickly instead of pumping efficiently. The atria may beat as fast as 300 to 600 times per minute. This is often called "the bag of worms" because the atria quiver like worms and can't pump blood. This allows blood to pool in the atria and is a common cause of blood clots. The clots can then break off, travel to the brain, and cause a stroke.
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Signs and Symptoms
Poor blood flow may cause low blood pressure. Common signs and symptoms include shortness of breath, palpitations, fatigue, confusion, chest pain, dizziness, and fainting. Presence of any of these should be considered a medical emergency and immediate medical help sought. Patients without a regular cardiologist should go to the emergency room where they will be evaluated by a cardiologist, especially if chest pain or shortness of breath is present.
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Many tests may be used to diagnose A Fib. The easiest is an EKG, usually a 12-lead EKG which shows 12 different views of the heart's rhythm. The test is noninvasive and painless, involving placing electrodes on the chest. Another noninvasive test is the echocardiogram, in which an ultrasound probe placed on the chest records the heart's activity, allowing for evaluation of heart valve function and any structural defects. A video is recorded and may be reviewed by the physician and forwarded to another physician.
A simple chest x-ray shows the condition of the heart and lungs as well as any fluid buildup in the lungs caused by A Fib. Transesophageal echocardiography, or TEE is an invasive procedure in which a thin tube with a camera on the end is run down the esophagus. This allows the physician to view the atria and see if any blood clots are developing.
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Anti-arrhythmic drugs are usually used first to try and convert the heart to a normal rhythm. The patient is typically in the hospital on a heart monitor which constantly monitors the heart's rhythm. There are many classes of drugs, including beta blockers, calcium channel blockers, sodium channel blockers, and potassium channel blockers. One or more drugs may be needed for the desired result. Some of the more popular anti-arrhythmics include amiodarone, Cardizem, metoprolol, and digoxin. Coumadin is a blood thinner frequently prescribed to prevent clot formation.
If drugs do not control the A Fib, the next step is cardioversion. This is similar to a patient who is "shocked" during a code. Light sedation is given to control pain. Many times the first shock is successful. Although 95% of patients respond successfully to cardioversion, 75% of them experience a recurrence of A Fib within one to two years. If cardioversion is unsuccessful, atrial ablation may be done. In this procedure, a catheter is threaded through an artery, typically in the groin. Radiofrequency current is applied to small areas to destroy the tissue and normalize the electrical impulses.
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A Fib is usually seen in older patients, so the risk rises along with age. Any type of heart disease such as valve disorders, heart attack, and coronary artery disease increases the risk. High blood pressure, alcohol use, poor nutrition, smoking, and obesity are other factors which may contribute to A Fib, as these lead to damage in the heart. Many of these factors can be controlled through lifestyle changes, such as regular exercise, quitting smoking, and focusing on fresh fruits and vegetables and eliminating junk and high-fat foods.
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Successful management of A Fib requires working closely with a cardiologist. Taking medications exactly as prescribed, following suggestions for lifestyle changes, keeping regular appointments, and reporting any recurrence of symptoms is crucial. Uncontrolled A Fib can lead to heart failure or stroke and may even lead to death.
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The National Lung, Heart and Blood Institute: http://www.nhlbi.nih.gov/health/dci/Diseases/af/af_what.html
Medicine Net: http://www.medicinenet.com/atrial_fibrillation/article.htm
Mayo Clinic: http://www.mayoclinic.com/health/atrial-fibrillation/DS00291
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McGill University Molson Medical Informatics Project: http://sprojects.mmi.mcgill.ca/cardiophysio/default.htm