Atrial fibrillation is a disorder found in about 2.2 million Americans. During atrial fibrillation, the heart’s two upper chambers beat chaotically and irregularly out of coordination with the two lower chambers of the heart. In a normal heart rhythm, the impulse generated by the sinoatrial node spreads through the heart and causes contraction of the heart muscle and pumping of blood. In AF, the regular electrical impulses of the sinoatrial node are replaced by disorganized, rapid electrical impulses which result in irregular heart beats. The risk of developing atrial fibrillation increases with age.
AF affects four percent of individuals in their 80s. When a patient spontaneously alternates between AF and a normal rhythm, the condition is known as paroxysmal atrial fibrillation. When a patient continues with AF as the dominant cardiac rhythm without reversion to the normal rhythm, the condition is known as chronic atrial fibrillation.
Atrial fibrillation is often caused by changes in your heart that occur as a result of heart disease or high blood pressure. Episodes of atrial fibrillation can come and go, or you may have chronic atrial fibrillation. Although atrial fibrillation usually isn’t life-threatening, it can lead to complications. Treatments for atrial fibrillation may include medications and other interventions to try to alter the heart’s electrical system.
Atrial fibrillation is the most common, abnormal rhythm of the heart. The AV node (and the ventricles) are therefore bombarded with frequent, irregular electrical impulses. As a result, the heart rate becomes fast and irregular, and the normal coordination between the atria and the ventricles is lost. During atrial fibrillation, the atria are stimulated 350 to 600 beats per minute or even more, much faster than the normal sinus rate of 60 to 100 beats per minute. Fortunately, the AV node cannot conduct all of these impulses. It allows up to approximately 170 impulses per minute to get through, though in an irregular fashion. If the ventricles beat too fast to fill completely with blood between beats, an inadequate amount of blood is pumped out of the heart to the rest of the body.
The causes of atrial fibrillation include coronary heart disease, an overactive thyroid, high blood pressure, acute lung infections such as pneumonia, rheumatic heart disease heart, lung surgery and drinking excessive amounts of alcohol. Some patients with atrial fibrillation have no apparent cause. When this occurs in patients under age 60 to 65, it is called lone atrial fibrillation. The cause is not well understood, but the risk of blood clots is much lower in these patients.
You may not have any symptoms but palpitations (an awareness of your heartbeat) are common. Some people may feel faint at times. Other people, including those with another heart condition, such as coronary heart disease or valvular heart disease, may also get breathless. Rapid and irregular heart rates may be perceived as palpitations, exercise intolerance, and occasionally produce angina and congestive symptoms of shortness of breath or edema.
Sometimes the arrhythmia will be identified with the onset of a stroke or a transient ischemic attack (TIA). It is not uncommon to identify atrial fibrillation on a routine physical examination or electrocardiogram (ECG/EKG), as it may be asymptomatic in some cases. Paroxysmal atrial fibrillation is the episodic occurrence of the arrhythmia and may be difficult to diagnose. Episodes may occur with sleep or with exercise, and their episodic nature may require prolonged ECG monitoring (e.g. a Holter monitor ) for diagnosis.
Treatment may include:
