In a normal heart, electrical impulses pace the rhythm at which the heart contracts and relaxes. The sinoatrial (SA) node triggers the electrical impulse, causing the upper chambers (atria) to contract. The signal travels through the atrioventricular (AV) node to the atrioventricular bundle, which divides into the Purkinje fibers that carry the signal and cause the lower chambers (ventricles) to contract. The electrocardiogram (EKG, ECG) above shows this normal electrical activity.
In atrial fibrillation, erratic electrical impulses in the upper chambers of the heart (atria) cause those chambers to fibrillate, or quiver. This results in an irregular and frequently rapid heart rate. The irregular, sawtooth pattern in the electrocardiogram (EKG, ECG) shows these erratic impulses.
For this nonsurgical procedure, a catheter is inserted into a vein in the groin and threaded up through the vein into the heart.
An electrode at the tip of the catheter sends out radiofrequency energy, creating heat that destroys (ablates) the atrioventricular (AV) node or other heart tissue that is responsible for the erratic impulses.
If the AV node is ablated, a permanent pacemaker is implanted that paces the ventricle. The pulse generator and battery part of the pacemaker are implanted under the skin of the chest. The electrocardiograms (EKG, ECG) above show the heart's electrical activity during atrial fibrillation and when a heart has a pacemaker.
Last Revised: November 2, 2010
Author: Healthwise Staff
Medical Review: E. Gregory Thompson, MD - Internal Medicine & John M. Miller, MD - Electrophysiology
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