AV Node Ablation (and Pacemaker Implantation)
About AV Node Ablation and Permanent Pacemaker Implantation
Ablation of the AV (atrio-ventricular) node can be performed in order to prevent rapid heart rhythms (such as atrial fibrillation or AF) in the upper chambers of the heart (atria) from being transmitted to the lower chambers (ventricles). It is relatively straightforward to perform and is very effective in preventing these rapid heart rhythms from otherwise causing excessively fast heart rates that can lead to shortness of breath, palpitations, dizziness or other cardiac complaints. Since the AV node is usually the only pathway for the hearts conduction system to reach the ventricles, all patients must first have a permanent pacemaker implanted so that the pacemaker can provide a normal heart rate.
Ablation of the AV node in atrial fibrillation does not improve atrial function (it still allows the AF to continue and simply prevents it's rapid conduction to the ventricles) and so it is not usually the first line therapy for patients with this condition.
The Procedure
As mentioned above, the first step is to implant a permanent pacemaker (see section entitled ‘Permanent Pacemakers’) to provide a normal heart rate for patients after the AV node or normal conduction system has been ablated. This is usually done at least two weeks prior to the AV node ablation to ensure that there are no problems with the pacemaker lead position since after an AV node ablation patients are often dependent upon their pacemaker for a normal heart beat. When the AV node ablation is then performed, a single ablation catheter is passed up to the heart (under X-ray guidance) through the femoral vein at the top of the leg in order to cauterise the node. This part of the procedure usually only takes 15-30 minutes and can be done with just local anaesthesia if needed.
Patients with a permanent pacemaker and AV node ablation will still have rapid heart rhythms in the upper chambers of the heart, the only difference is they will no longer cause rapid heart rates. For this reason it is important to remain on anti-coagulation after the procedure to help prevent blood clots forming in the atria, however, patients may be able to stop other medications that are were used to slow the heart rate (after discussion with their cardiologist).
The diagram above shows a normal heart with four chambers (right and left atria at the top and right and left ventricles at the bottom). The hearts normal electrical system is shown in yellow. This patient had a permanent pacemaker lead placed in the right ventricle (in black) two weeks earlier so that AV node ablation could be performed. This is done by passing the ablation catheter (in blue) up to the heart (through the femoral vein at the top of the leg) to cauterise the AV node and prevent any further rapid conduction of heart rates from the atria.