Atrial fibrillation is an abnormal heart rhythm in which the upper heart chambers, or atria, quiver in a disorganized, chaotic fashion. This makes the heart pump inefficiently, which in turn increases the risk of blood clots. The rhythm tends to be fast and irregular. Numerous heart problems, lung problems, hormone abnormalities or drugs may cause atrial fibrillation. A condition known as lone atrial fibrillation has no apparent cause.
Cardiovascular Problems
Any condition that disrupts the normal electrical conduction system of the heart may lead to atrial fibrillation. Congenital heart disease, heart defects present from birth, may alter the normal rhythm of the heart. A heart attack may damage cardiac cells and impair normal function. Leaky or narrowed heart valves could cause atrial fibrillation. Surgery to repair an abnormal valve or to bypass diseased coronary arteries may trigger this arrhythmia. When the heart fails to pump adequately, it tends to enlarge, a condition known as congestive heart failure. This is also associated with atrial fibrillation, notes Medline Plus. Sick sinus syndrome, which is a primary disorder of the pacemaker and electrical system of the heart, may result in atrial fibrillation. Pericarditis is an inflammatory condition affecting the sac around the heart, often caused by a viral infection. High blood pressure is a known cause. An enlarged heart, or hypertrophic cardiomyopathy, is also on the list of conditions that may lead to atrial fibrillation.
Pulmonary Problems
Blood that exits the right ventricle of the heart travels to the lungs to pick up oxygen. Sometimes this flow of blood is impaired by primary lung problems, and this can cause atrial fibrillation. A pulmonary embolism, or blood clot in the lungs, is one such condition, according to Cleveland Clinic. Long-term lung diseases such as chronic obstructive pulmonary disease, pulmonary fibrosis, emphysema or chronic bronchitis may cause atrial fibrillation. Even pneumonia could trigger it.
Endocrine Problems
The thyroid gland plays an important role in regulating the body's metabolism. An overactive thyroid gland, a condition known as hyperthyroidism, may cause atrial fibrillation, notes MayoClinic.com. Diabetes is also a factor that increases the risk of this condition.
Drugs
Stimulant drugs such as amphetamines, cocaine and caffeine may cause atrial fibrillation. Alcohol use, in a chronic or binge fashion, may incite fibrillation of the atria. Any prescription medication that affects the heart and its conduction system, such as digoxin, diltiazem and verapamil, could potentially lead to atrial fib as well.
Lone Atrial Fibrillation
MayoClinic.com notes that lone atrial fibrillation is seen in people with no identifiable risk factors for atrial fibrillation. This condition, and all other types of atrial fibrillation, are seen more often in older patients.
