How the heart's electrical system works
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) shows this normal electrical activity.
How atrial fibrillation happens
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.
Catheter is threaded through a vein to the heart
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.
AV node is destroyed
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.
Pacemaker controls the heart rhythm
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.