ATRIAL FIBRILLATION
Atrial fibrillation, also called "atrial fib" or "a-fib", is an irregular heart rhythm. It is defined as "irregular, rapid contractions of the atrium". Atrial fibrillation is the most common arrhythmia and affects more than two million Americans. Since the chances of developing atrial fibrillation increase with age, this arrhythmia affects as much as 20 percent of the population over age 80.
Before we explain atrial fibrillation, it is necessary to understand how the normal electrical system works. In order to pump blood through your body efficiently, the electrical system of the heart causes the chambers of the heart to contract and relax. The heart muscle is controlled by electrical messages that come from a cluster of cells in the right atrium (upper chamber of the heart) called the sinus node (figure 1). The electrical messages then travel to the AV node between the right atrium and ventricle (lower chamber of the heart) before the ventricle contracts.
 <!--[endif]-->Electrical System of
The sinus node is the heart’s natural pacemaker. It sends out an electrical signal that starts each heartbeat by telling the atria (upper chambers) to contract. The AV node is the next stop for the signal as it travels through the heart. The AV node receives the signal from the atria and sends the signal to the ventricles. Pathways carry the signal through the ventricles, it tells them to contract. |
 <!--[endif]-->Atrial Fibrillation
During atrial fibrillation electrical signals begin in several areas of the atria causing these upper chambers of the heart to beat very quickly or quiver (figure 2). The ventricles may continue to pump blood throughout your body at a relatively normal rate. However, sometimes the rate may be too rapid, leading to inefficient ventricular pumping function. |
What causes Atrial Fibrillation?
Most people with atrial fibrillation have other forms of heart disease such as long term hypertension (high blood pressure), abnormalities of the heart valves, or abnormalities of the pumping function of the heart (heart failure). However, in one-third of the population, the cause of atrial fibrillation is unknown. Possible causes in this population include exposure to stimulants such as alcohol, drugs, caffeine, etc. Other causes include abnormalities of the thyroid, muscle of the atria, individual heart cells or groups of heart cells.
What are the symptoms?
The symptoms of atrial fibrillation may be different with each person. In fact, many people have atrial fibrillation without knowing it because they do not experience any symptoms. It is important to recognize the following symptoms and discuss them with your health care provider.
- Palpitations (fluttering or fast heart beat)
- Dizziness or lightheadedness
- Shortness of breath
- Exercise intolerance
- Weakness
- Chest pain
- Fainting spells
What are the dangers of atrial fibrillation?
Stroke: The most important problem to be aware of is the potential to develop blood clots. When the atria quiver or beat irregularly, there is a greater chance that blood clots will form. This occurs because blood pools in the atrium and the heart does not beat forcefully. A stroke can occur if a blood clot travels to the brain and blocks supply of blood to the brain. Common signs and symptoms of a stroke, also called "brain attack", include:
- numbness, weakness, or inability to move a body part; usually presents on one side of the body and affects the face, arm, or leg
- sudden blurred, decreased, or double vision
- dizziness, loss of balance or coordination
- sudden, severe headache
- difficulty speaking or understanding others
It is important to call "911" and seek emergency care immediately if you believe you are experiencing any of these symptoms.
Cardiomyopathy/Heart failure: In about 20 percent of patients, long term atrial fibrillation can weaken the heart muscle. This condition is referred to as cardiomyopathy or heart failure. If atrial fibrillation causes the ventricles to beat rapidly, the heart muscle will pump less effectively. Taking medications regularly to slow the electrical impulses from the atria to the ventricles is helpful in preventing cardiomyopathy.
Life Changes
Living with atrial fibrillation does not have to dramatically affect your lifestyle. In order to prevent symptoms such as palpitations, it is generally recommended that patients avoid alcoholic and caffeinated beverages. Other types of stimulants (non-prescription medications and supplements) should be avoided as well. Exercise restrictions generally depend on any underlying heart disease you may have rather than on the basis of having atrial fibrillation.
How is it diagnosed?
Atrial fibrillation is diagnosed by an electrocardiogram (ECG or EKG). An EKG records the electrical activity of the heart. In addition, other tests such as a holter monitor or event monitor record your heart rhythm for a certain time period. Echocardiogram, or an ultrasound of your heart, can also reveal atrial fibrillation.
What medications are available?
Preventing blood clots: A class of medications called anticoagulants, or Coumadin, are important in decreasing your risk for blood clots. Anticoagulants are referred to as "blood thinners" because they work to prolong the time normally required for your blood to clot. They do not affect the thickness of your blood but rather decrease the risk for clot formation within the heart and blood vessels.
Heart rate control: Medications are also available to slow the transmission of electrical signals that pass through the heart. The three most common types of medication are digitalis, beta blockers, and calcium channel blockers. Each medication works a little differently but they all help to make your heart pump more efficiently and relieve possible symptoms.
Restoring normal heart rhythms: Antiarrhythmic medications are sometimes prescribed to prevent abnormal heartbeats. In some cases, antiarrhythmics can even restore a normal heart rhythm.
What other treatments for atrial fibrillation are available?
Electrical Cardioversion: While chemical cardioversion includes the antiarrhythmic medications described above, electrical cardioversion uses electricity to help restore your heart to a normal rhythm. During electrical cardioversion, your physician will give your heart a brief electrical shock. This shock stops all electrical activity in your heart for a brief moment particularly the abnormal signals that cause atrial fibrillation. The expected outcome of this procedure is to have a regular, normal heart rhythm take over. Unfortunately, this does not always occur. More than one procedure may be needed to restore a normal rhythm in some people while in others, electrical cardioversion may not work at all.
Catheter Ablation: Catheter ablation is performed by an electrophysiologist, a subspecialist in cardiology. During catheter ablation, a few cells of the atria, which are causing the fast heart rhythm are ablated or eliminated. During this procedure, a special wire (catheter) is inserted through a blood vessel, usually a leg vein, and advanced into the heart. The tip of the catheter is placed near the problem electrical cells and energy is sent through the catheter. Most people who undergo ablation report improved symptoms.
Which treatment is best?
Just as each person's situation is different, so is the treatment strategy that you and your health care provider will agree to. Most people require more than one type of treatment. In addition, the possible benefits and risks must be considered with each form of treatment. We invite you to discuss with your health care provider which of the current and future options will meet your specific needs.
What can I do?
In addition to taking your prescribed medications, it is important that you contact Midwest Heart Specialists if you feel that your symptoms of atrial fibrillation are uncontrolled. These symptoms may include palpitations, dizziness or lightheadedness, chest pain, weakness, shortness of breath, and/or exercise intolerance. If you are concerned about symptoms, monitor your heart rate by checking your pulse.
In order to help prevent a stroke, it is important for you to monitor your blood values or INR, as directed when taking an anticoagulant (Coumadin). Also, inform your health care provider if you have started any new medications or have changed your diet to include large amounts of green, leafy vegetables.
It is vital that you call 911 or emergency services immediately if you think you are experiencing any stroke symptoms as described above.
We encourage you to discuss any questions, concerns, or fears with your health care provider.