Atrial Fibrillation

In health, the sinus node activates the atria which causes a concerted contraction that empties blood into the ventricle. However, during atrial fibrillation, there is disorganized activity in the atria. The prevalence of atrial fibrillation increases with age. Sometimes there is an underlying cause for atrial fibrillation that needs to be considered. These abnormalities may include sick sinus syndrome, thyroid disorders, mitral valve or tricuspid valve regurgitation, aortic valve disease, hypertension, and coronary artery disease. Since we believe that atrial fibrillation exaggerates normal physiology, if somebody presents in rapid atrial fibrillation, underlying medical etiologies need to be considered (for example, infection, pulmonary embolism, congestive heart failure, pulmonary disease).

There are three components to therapy for atrial fibrillation that need to be considered. Because atrial fibrillation increases patient risk of stroke, anticoagulation with warfarin needs to be considered if it can be safely administered. The second component is heart rate control. This can be done with B-blockers or non-dihydropyridine calcium channel blockers. Rate control needs be done carefully in acute setting when the patient is ill. Since the human body primarily increases cardiac output by rapid heart rate rather than stroke volume, sometimes blunting the heart rate response during rapid atrial fibrillation in the setting of acute illness can cause hypotension. These rate control agents can usually be safely administered once any underlying medical etiologies is considered. The ultimate rate control for atrial fibrillation, is AV node ablation and placement of a pacemaker.

The third component of atrial fibrillation therapy is rhythm control. This can be done by both pharmacologic and non-pharmacologic approaches. Usually pharmacologic approached is initially used, and non pharmacologic is reserved for a second line therapy. Although many times anti-arrhythmics can maintain sinus rhythm, there is the potential for side effects. A non-pharmacologic approach by catheter ablation can be considered which usually involves pulmonary vein isolation and/or left atrial substrate modification. Reported success rates have varied widely. However, compared to a standard ablation, the risk of the procedure is increased.