In a normal heart, 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) tracing, above, shows this normal electrical activity.
In atrial fibrillation, erratic electrical impulses from the pulmonary veins can cause the upper chambers of the heart (atria) to fibrillate, or quiver, resulting in an irregular and frequently rapid heart rate. The irregular, sawtooth pattern in the electrocardiogram (EKG, ECG) tracing shows these erratic impulses.
For this nonsurgical procedure called catheter ablation, a thin tube called a catheter is inserted into a vein in the groin and threaded up through the vein into the heart. A small puncture in the tissue that divides the right and left chambers (septum) allows the catheter to pass into the left atrium.
An electrode at the tip of the catheter sends out radiofrequency energy, creating heat that destroys (ablates) the tissue that is causing atrial fibrillation. In this image, the heat is destroying tissue at the base of the pulmonary vein. (The pulmonary veins bring blood back from the lungs to the heart.)
Catheter ablation creates scar tissue that prevents impulses from leaving the pulmonary veins or eliminates the impulses altogether.
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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