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
For this nonsurgical procedure, a catheter is inserted into a
vein in the groin and threaded up through the vein into the
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
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.
November 2, 2010
E. Gregory Thompson, MD - Internal Medicine & John M. Miller, MD - Electrophysiology
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