Catheter Ablation of Atrial Fibrillation

During normal rhythm, an electrical impulse originates from the normal pacemaker of the heart (sinus node) and travels through the upper chambers of the heart (the right and left atria) to cross over a bridge (AV node) to the pumping chambers (ventricles), causing a heartbeat. This is normal sinus rhythm. Atrial fibrillation (AF) is a heart rhythm disorder with rapid, irregular, and chaotic electrical activity in the atria (Figure). The atrial electrical signals bombard the AV node, and some pass through the AV node to the ventricles, producing a rapid, irregular rate and often causing symptoms of palpitations, shortness of breath, or fatigue. AF affects more than 2 million people in the United States alone; it is seen progressively more frequently as a person ages. MRI of the left atrium as viewed from the patient’s back and one mechanism hypothesized to result in AF. Pulmonary veins extend from each side of the atrium. A, A focus on one of the veins might fire and produce an electrical impulse (yellow arrows) that excites the rest of the atrium. B, With rapid firing, the electrical signals begin dividing as they circulate around the atrium. C, The focus is not firing, but the electrical impulses that it initiated continue to circulate around the atrium, producing atrial fibrillation. D, Location of ablation lesions (light blue circles) encircling the pulmonary veins on both sides of the atrium. These lesions prevent any triggers around the pulmonary veins from exciting the rest of the atrium and may interrupt paths needed for multiple impulses to circulate if they were to cause AF.There are 3 major treatment considerations for AF. First, in some people, AF promotes formation of blood clots in the atrium that can travel to the brain and …