Arrhythmias - Atrial Fibrillation: Treatment with AV nodal ablation and pacemaker

 

ATRIOVENTRICULAR JUNCTIONAL (AVJ) ABLATION AND PACEMAKER IMPLANTATION FOR CONTROL OF ATRIAL FIBRILLATION
© Alan B. Schwartz, M.D. 12/99 Ver 1.1

INTRODUCTION

Atrial fibrillation is the most common rhythm disturbance individuals face, as they grow older. In this disorder, the heart rates at rest can be very fast and irregular. They generally become even faster with exertion. To some, the heartbeats in fibrillation can feel very uncomfortable. The combination of the irregularity and the rapidity can cause fatigue and shortness of breath even with minor exertion.

Medical treatment suffices to control these abnormalities in the majority of the cases. However, sometimes the medicines which are used to control the heart rates themselves cause unacceptable side effects. These unwanted symptoms could include fatigue, shortness of breath with exertion, constipation, sexual dysfunction, lightheadedness or feelings of "just not feeling well". Other times, despite maximal amounts of medicines, atrial fibrillation may still not be adequately controlled.

For those infrequent times when medical therapy is inadequate, a pacemaker coupled with an atrioventricular junctional (AVJ) ablation offers symptom relief and an improvement in the quality of life without the need for medicines.

In a survey we did among our patients with persistent or intermittent atrial fibrillation who had severe symptoms and underwent an AVJ ablation and pacemaker, 86% felt that the procedure greatly improved their quality of life. No patients felt that they were worse and only 1 felt he was "the same".

This discussion will describe the how the procedure works.

AVJ ABLATION

The native pacemaker of your heart, called the sinoatrial node (SA node), is located in the right atrium, one of the upper chambers of your heart. The pacemaker cells from the SA node produce a regular electrical signal that is transmitted from the atrium to the ventricles via a conduction system that includes the atrioventricular node (AV node) or junction and the right and left bundle branches. This transmitted signal causes the ventricles to beat at the same rate as the atria. Without this transmission system, the natural pacemaker signals would not be able to synchronize with the ventricles and the ventricles would beat very slowly at their own intrinsic rate (about 35-45 beats/minute).

When the atria go into fibrillation, they generate hundreds of electrical signals each minute that bombard the atrioventricular junction in a chaotic fashion. Luckily, not all of these hundreds of signals get through the transmission system otherwise the ventricles would beat dangerously fast. But, despite this filtering effect of the AV node, the heart still beats fast and irregularly at 140 up to 200 times a minute at rest and even faster with exercise.

Medical therapy for heart rate control in atrial fibrillation is directed at controlling the heart rate of the ventricles. This is accomplished by using medicines that affect the AV node. These medicines would include AV nodal blocking drugs such as beta blockers (Inderol, Tenormin, Lopressor, Toprol, etc.) or calcium channel blockers (verapamil or diltiazem) or digoxin (Lanoxin) or amiodarone (Cordarone or Pacerone) or combinations of the above. These drugs affect the AV node so that many of the excessive signals get eliminated.

An alternative way to control the ventricular rate in atrial fibrillation is by destroying the AV node. This can be done somewhat easily by an AVJ ablation procedure. The result is that no abnormal (or normal) signals will be able to be transmitted from the atrium to the ventricles and, therefore, none of these medications (which are responsible for side effects) will be needed.

Of course, this procedure cannot be a "stand-alone" solution because the ventricles must get their commands to beat from some alternative source. This alternative source is a standard pacemaker. Therefore, a pacemaker is always implanted as a part of this procedure.

Many patients ask , "What happens if the pacemaker should malfunction?" The ablation procedure usually leaves the individual with a slow rhythm (35 to 45 beats/minute) that originates from the ventricles. While this is not fast enough for activities, it is adequate at rest and would provide a backup rhythm until the problem is diagnosed and corrected by your doctor.

The procedure is relatively safe and highly successful. In our experience, the success rate for this procedure is 97% and the complication rate is about 1.5%.