Atrial Fibrillation

   • What is Atrial Fibrillation?
   • Symptoms of AF
   • Medical Treatment
   • Catheter Ablation
   • Device Therapy






What is Atrial Fibrillation (AF)?
Atrial fibrillation (AF) is the most commonly diagnosed arrhythmia, which is characterized by fast and irregular heart rhythms. It is caused by electrical abnormalities located in the pulmonary veins of the left atrium.

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What are the symptoms of Atrial Fibrillation?
Individuals experience the symptoms of atrial fibrillation differently. Some who have this condition may not feel any symptoms, and their condition will go unnoticed until it is detected by a physician during a routine examination. Others may experience only minor symptoms, while some are sensitive to the slightest sensation. Symptoms commonly reported include shortness of breath, lightheadedness, palpitations, and/or chest discomfort.

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Medical Treatment for AF
The initial treatment for atrial rhythm disorders is antiarrhythmic drug therapy. These drugs can slow the conduction of rapid atrial fibrillation and/or convert atrial fibrillation to a normal sinus rhythm. Drugs, however, do not cure heart rhythm disorders, and they are not effective in all patients. They also require that a patient maintain a very strict schedule of follow-up care with his or her physician. Many patients with atrial fibrillation require a blood thinner, such as Warfarin, to prevent the formation of blood clots, which can cause a stroke.

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Catheter Ablation for Atrial Fibrillation - Current Indications
Many forms of AF are triggered or maintained by a single (or few) focus of muscle firing in the heart. In most patients, these sites have been mapped to the pulmonary veins (vessels which empty blood from the lungs to the left side of the heart). These venous structures have sleeves of atrial tissue extending from the heart (left atrium) for variable distances into the main branch or its tributaries. This musculature when diseased or damaged is capable of generating ectopic complexes, or repetitive activity at very rapid rates. In susceptible patients, this may lead to and maintains atrial fibrillation.

Elimination of the triggers can lead reduction or elimination of AF. Catheter ablation techniques have been designed and successfully applied to a variety of patients with AF targeting the pulmonary vein musculature. These muscle sleeves have discrete and limited connections to the atria, which may be vulnerable to catheter ablation. A mapping catheter and an ablation catheter are passed into the left atrium using a trans-septal puncture. The discrete connections of the pulmonary vein to the left atrium are mapped and precisely identified. These connections are then ablated using radiofrequency energy. The pulmonary vein is then progressively disconnected with the ultimate result of complete isolation of the pulmonary vein musculature from the left atrium. Each pulmonary vein is entered and serially ablated until all pulmonary veins are completely electrically disconnected. This can be achieved in about 99% of targeted veins. The pulmonary veins continue to serve as conduits of oxygenated blood to the left atrium.

This procedure is curative in approximately 70% of patients, who will then require no further medical therapy. An additional 20% of patients may respond to antiarrhythmic drugs that were previous ineffective, or have substantial reduction in AF events. About 10-15% of patients have no response, presumably due to alternate triggers in the heart. Some patients benefit from a second procedure if the first was unsuccessful. The procedure has a small risk of about 1-2%. Fortunately, serious complications are infrequent. The potential complications include pulmonary vein stenosis (narrowing of the opening of the pulmonary veins due to aggressive scar tissue formation), small risk of stroke and risk of cardiac perforation requiring catheter drainage or surgery. Risk of catastrophic complications (heart attack, esophageal perforation and death) is extremely small.

Ideal candidates include patients who have paroxysmal AF without major structural heart disease. Selected patients with persistent or chronic AF may be also be candidates for ablation. Catheter ablation is an effective tool offering a curative treatment of atrial fibrillation.

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Device Therapy for AF
In a subset of patients with paroxysmal (intermittent) or persistent atrial fibrillation, devices can be used to either prevent atrial fibrillation or convert it to a normal sinus rhythm. These devices include pacemakers and implantable cardioverter defibrillators (ICD).

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