Atrial fibrillation, or AFib, is the most common type of irregular heartbeat, or arrhythmia. With AFib, your heart beats much faster than the normal 60 to 100 beats per minute. To create a normal heart rhythm, or sinus rhythm, your heart’s upper and lower chambers must work in concert. But with AFib, the activity of those chambers is out of sync.
The heart pumps blood to the rest of the body, and the pumping is controlled by the heart’s own electrical system. Each heartbeat is essentially an electrical impulse that navigates through the heart. The impulse is generated by a small mass of specialized tissue in the right upper chamber, or atrium, of the heart called the SA node.
The SA node sends the electrical charge to the AV node, which is located in the wall of tissue that separates the right and left atria called the interatrial septum. The AV node conducts the impulse from the atria to the ventricles, the bottom chambers of the heart. Each impulse moves blood through the atria into the ventricles, from where it is pumped out to the rest of the body.
With AFib, the atria don’t move blood into the ventricles effectively, so the ventricles can’t pump blood to the body efficiently. This can cause your heart to beat irregularly, to be very rapid and feel like quivers or thumps in your chest. AFib can lead to serious heart-related complications including heart failure.
When blood is not pumped efficiently out of the ventricles, it is more likely to clot. If a blood clot leaves the ventricles and enters the bloodstream, it can lodge in an artery going to the brain and cause a stroke. People with atrial fibrillation are 5 to 7 times more likely to have a stroke than the general population. And about 15 to 20 percent of people who have strokes have this heart arrhythmia.
It is estimated that between 2.7 million and 6.1 million people in the United States have AFib. It is more common with age, so as our population gets older, this number will increase. Further, more than 454,000 hospitalizations in which AFib is the primary diagnosis occur each year, and AFib contributes to about 158,000 deaths annually. And that number is expected to rise.
A congenital heart disorder can cause AFib, and certain diseases and conditions that can damage your heart can result in arrhythmia. Possible causes of atrial fibrillation include high blood pressure, heart attack, coronary artery disease, heart valve disease, chronic lung disease, previous heart surgery, an overactive thyroid or metabolic disease, a viral infection, and exposure to stimulants such as caffeine, cocaine, tobacco or alcohol.
Some people have no symptoms and don’t know they have AFib. Their arrhythmia is typically detected during a physical exam when the doctor performs a test called an electrocardiogram, or ECG, which measures heart rhythm. Common symptoms of AFib include the following:
- Rapid and irregular heartbeat
- Fluttering or “thumping” in the chest
- General fatigue
- Dizziness, faintness or confusion
- Chest discomfort
- Shortness of breath
In addition to an ECG, your doctor may use other tests to help diagnose AFib. These may include a Holter or portable event monitor, which records your heart’s electrical activity over a period of time. Transesophageal echocardiography, or TEE, uses sound waves to take pictures of your heart through your esophagus. Your doctor uses this test to look for blood clots.
Treating AFib generally includes making certain lifestyle changes, including quitting smoking and limiting your intake of alcohol and caffeine. Also, control your high blood pressure and blood sugar levels, exercise regularly and maintain a healthy weight, and eat a heart-healthy diet that is low in salt, saturated fat, trans fats and cholesterol.
Initially, medications are used to treat atrial fibrillation. These include medications that control heart rhythm, which help return the heart to normal sinus rhythm. Thera are also medications that control heart rate. These work by preventing the ventricles from beating too rapidly. Anticoagulant medications, or blood thinners, which reduce the risk of blood clots and stroke, are also typically prescribed to patients with AFib.
Among the nonsurgical procedures for atrial fibrillation are electrical cardioversion and radiofrequency ablation. With electrical cardioversion, an electrical shock is placed on the outside of the chest to “reset” the heart to normal sinus rhythm.
During radiofrequency ablation, a catheter is inserted through a blood vessel and gently guided into your heart. Your malfunctioning tissue is destroyed using radiofrequency energy delivered through the catheter, and the tissue can no longer send abnormal signals.
Implanted pacemakers are among the surgical procedures for atrial fibrillation. Another is the maze heart surgery. During this procedure, the surgeon cuts small slits in the upper part of your heart. The scar tissue that results interferes with the transmission of electrical impulses that cause AFib, and normal heart rhythm is restored.