Atrial fibrillation is an irregular heart rhythm associated with disorganized electrical activity in the upper two chambers of the heart. Abnormal electrical impulses cause the atria to beat very fast and in an uncoordinated manner. This is called fibrillation. Paroxysmal atrial fibrillation indicates that the arrhythmia occurs at varying intervals, rather than consistently or constantly. The result of the rapid, irregular beats is ineffective filling of the ventricles, the bottom two chambers of the heart that pump blood out to the body.
Atrial fibrillation is the most common heart arrhythmia. The underlying cause is often unknown, but the risk increases with age. As many as 4% of those over the age of 65 are affected by atrial fibrillation. Other risk factors include coronary artery disease, uncontrolled high blood pressure, and obesity.
Some non-cardiac conditions can also cause this condition. This includes hyperthyroidism and imbalances of potassium, calcium, or magnesium. In these cases, atrial fibrillation usually reverses when the underlying condition is treated.
Many of the symptoms associated with atrial fibrillation are due to rapid heart rate. A normal resting heart rate is 60 to 100 beats per minute. During an episode of paroxysmal atrial fibrillation, the heart may beat as many as 175 times per minute. Some patients actually feel the rapid irregular beats of the heart. These are called palpitations.
Ineffective filling of the ventricles also leads to many symptoms of atrial fibrillation. Patients often experience shortness of breath and chest pain. Fatigue, decreased ability to exercise, and dizziness are also common. When atrial fibrillation is severe, confusion and fainting may occur.
Atrial fibrillation is often first detected by a health care provider listening to the heart. The diagnosis is then confirmed with an electrocardiogram (EKG), which takes readings of the electrical activity of the heart. Occasionally, an echocardiogram of the heart may be necessary. This is a test that visualizes the heart while it is beating.
For paroxysmal atrial fibrillation, episodes occur intermittently and may only last a few seconds or minutes. To confirm this diagnosis, patients may wear a portable, continuous EKG for one or two days. This is called a Holter monitor. A similar device, called an event monitor, only takes EKG readings when the patient experiences symptoms and pushes a button. An event monitor can be worn for several months.
Due to the intermittent nature of this condition, many patients with this condition do not require any treatment at all. This is particularly true if they do not experience symptoms. Patients are advised to minimize stress whenever possible. Over half of patients with paroxysmal atrial fibrillation list stress as the number one trigger of fibrillation episodes.
There are other steps patients can take to prevent episodes. Caffeine, alcohol, and nicotine should be avoided, as all have been shown to be triggers. Over-the-counter cold medications such as pseudoephedrine can precipitate episodes and should be avoided as well. Stopping smoking is also encouraged, as it significantly contributes to the development of heart disease. High blood pressure should be controlled for the same reason.
If symptoms begin to occur more frequently, patients with paroxysmal atrial fibrillation may take medications that slow the heart rate to less than 80 beats per minutes. This includes beta-blockers, calcium channel blockers, and digoxin. Rate control allows the ventricles more time to completely fill with blood. Note that this strategy manages the symptoms but does not correct the underlying arrhythmia.
When symptoms are not managed effectively with rate control alone, patients may take medications that correct the underlying rhythm problem. Examples include sotalol, amiodarone, and ibutilide. Long-term therapy has the potential to cause many side effects, so patients are screened carefully before starting antiarrhythmic drugs.
There are also non-drug treatment options for atrial fibrillation. The most commonly used is electrical cardioversion. This is a procedure that attempts to convert the abnormal rhythm to a normal one with a controlled electrical current passed through the heart.
Atrial fibrillation itself is not a life-threatening condition, but there are two potentially life-threatening complications: stroke and heart failure. The risk of stroke results from the pooling of blood in the atria during fibrillation. This can cause a blood clot to form, and in some cases, break free and go to the brain. Persistent or permanent atrial fibrillation requires treatment with blood thinners to decrease this risk.
The ineffective filling of the ventricles means that the heart is not pumping enough oxygenated blood to the tissues of the body. This is heart failure, and once it occurs, it often cannot be reversed. Educating patients about the reversible risk factors, such as obesity and high blood pressure, will help to prevent atrial fibrillation before it occurs.