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 non-surgical procedure, catheters are inserted into a vein, typically in the groin or neck, and threaded through the vena cava vein into the right atrium of the heart.

An electrode at the tip of the catheter sends out radio-frequency energy, creating heat that destroys (ablates) the atrioventricular (AV) node or other heart tissue that is responsible for the erratic impulses.

When 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) show the heart's electrical activity during atrial fibrillation and when a heart has a pacemaker.