Etiology: What causes AF?

Referencing week one's post, we know AF is an electrical problem with the heart's pacemaker. This impulse can progress to AF from a few different causes. Chronic hypertension is very common, as long-term high blood pressure places an increased workload on the heart muscle, causing it to grow in size. Unfortunately, bigger is not always better, especially regarding the heart. Overtime, this leads to heart disease As the muscle grows, the neurons (electrical cells) are unable to deliver an adequate impulse to stimulate an efficient contraction of the muscle. This can eventually cause the pacemaker (SA node) to perform out of sequence, causing misfires. Another cause may be a problem with the actual structure of the heart, predisposing the individual to a greater risk of having the abnormal rhythm. This may be caused by family history and involve the valves of the heart or actual pacemaker. (2)

AF may present in three different categories; paroxysmal, persistent, and permanent. Paroxysmal AF may last up to a few days but stops on its own. This may progress to a more chronic type or could acute and triggered by over stimulation of the vagus nerve (affects the nervous system and blood vessels involved in heart rate and rhythm). Persistent AF is less common than paroxysmal but requires medical intervention in order to restore the hearts normal rhythm. Cardioversion is often used, this is electroshock therapy, a treatment which is intended to reset the heart back into its regular rhythm. Permanent AF is exactly what it sounds like. Cardioversion will not be effective for restoring the rhythm back to normal. This can occur over time with chronic episodes and poor controlled AF or failure to treat early onset AF. Lifelong treatment will be required. (1)

The biggest concern of being in an AF rhythm is the risk of blood clot formation. Because the atrial chambers are not distributing all their blood into the ventricle chambers, the risk of blood pooling inside the atria increases. If this is not resolved, the blood will clot and depending on which chamber the clot forms, the result could be either a pulmonary embolism (clot in the lung) or stroke (clot in the brain). 

Some of the Several Causes

References:

1.     Pathophysiology and Prevention of Atrial Fibrillation. (2001, January 1). Retrieved January 20, 2015, from http://circ.ahajournals.org/content/103/5/769.full#cited-by

2.     Kannel, W., & Benjamin, E. (2008, February 15). Final Draft Status of the Epidemiology of Atrial Fibrillation. Retrieved January 15, 2015, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2245891/#FN2

3.     Atrial Fibrillation, What Causes It? [Motion picture]. (2010). United States: EmpowHer.