Atrial Fibrillation

What is atrial fibrillation?

Atrial fibrillation is the most common cardiac arrhythmia, or abnormal heart rhythm seen today. Approximately 2.2 million Americans suffer from this disorder. On average, there are 160,000 new cases of diagnosed each year. Atrial fibrillation is a disorder in which the upper two chambers of the heart no longer beat in a normal, synchronized fashion. Rather, electrical impulses move about both atria in a chaotic, or circus-movement pattern, resulting in activation of the atria at somewhere between 400 and 600 times per minute. The impulses coursing through the atria traverse through a structure called the A-V node to reach the ventricles. The hallmark of atrial fibrillation is an irregular rhythm where the ventricles, or bottom pumping chambers of the heart, beat in a very chaotic fashion.

What are the warning signs and symptoms of atrial fibrillation?

Individuals with atrial fibrillation may have heart rates that are too slow, too fast, or within the normal range. Individuals with atrial fibrillation may experience no symptoms, limited symptoms in the form of palpitations, or catastrophic symptoms such as loss of consciousness due to rates which are either too fast or too slow . A major risk of atrial fibrillation is stroke, with the incidence of stroke approximately five times that of similar-aged individuals who do not have atrial fibrillation. The risk factors which appear to increase the risk of stroke in individuals with atrial fibrillation include age greater than 65 years, presence of diabetes mellitus, presence of hypertensive heart disease, congestive heart failure, mitral stenosis (tight mitral valve), or history of prior stroke or near-stroke (Transient Ischemic Attack). The risk of stroke in individuals with atrial fibrillation may be significantly reduced by use of anticoagulant therapy in the form of Warfarin.

What are the treatment options for atrial fibrillation?

Treating atrial fibrillation varies by individual. Your doctor will take a thorough history and perform a comprehensive physical examination to determine if your atrial fibrillation is due to another problem, such as hypertension, coronary artery disease, valvular heart disease, or thyroid dysfunction. Oftentimes, these primary problems may be treated with resolution of the atrial fibrillation. If the atrial fibrillation is not corrected by resolution of the primary problem, the patient is oftentimes anticoagulated for three to four weeks, and subsequently cardioverted back to normal rhythm. Cardioversion may occur in the form of an antiarrhythmic medication either orally or intravenously, or by the administration of electric shock therapy through patches placed on the chest. Electrical cardioversion occurs in a hospital setting, with the patient under brief general anesthesia for two to three minutes. Following cardioversion, patients are frequently kept on anticoagulant therapy for a minimum of three to four weeks to prevent a stroke that may occur up to that period of time following cardioversion. At times, atrial fibrillation is allowed to persist, without an attempt at cardioversion. In that case, the main concern, aside from anticoagulation, is to control the rate of the ventricles, and that is typically done with either medical therapy or with use of a pacemaker in combination with A-V Nodal Ablation (see below).

Other Treatment Options

At times, medications do not adequately control the ventricular rate in atrial fibrillation. In these cases, a commonly performed procedure today is to place a pacemaker, either single or dual-chamber, followed by catheter ablation of the A-V Node. While this does not abolish the atrial fibrillation itself, or the need for anticoagulant therapy, it does abolish the slow or rapid ventricular response that may occur, and allows the patient to have a regular, normalized heartbeat.

One of the newer procedures for atrial fibrillation involves placing catheters into the left atrium near the pulmonary veins, which are the vascular channels that drain blood returning from the lungs to the heart. Atrial fibrillation today is thought to originate from small islands of tissue within the pulmonary veins, and catheter-ablation at the entrance of the vein into the left atrium may abolish the atrial fibrillation from occurring.