Friday, February 16, 2007

Atrial Fibrillation Ablation Nirvana

Sometimes you have moments when you are reaffirmed that you have one of the coolest jobs in the world.

Atrial fibrillation is a remarkably common heart rhythm disorder that effects many, many individuals. For many a cardiologist, it can be remarkably frustrating to treat, since our drugs are often ineffective or toxic. Patients feel a wide range of symptoms: some feel nothing while others are debilitated by the irregularity or rapid heart rates that can accompany this arrhythmia.

I have posted on this before and interested readers can review the methods (and risks) of how I perform this procedure using a "wide area" catheter ablation technique here. On occassion, however, even after performing a catheter ablation procedure (also called a "pulmonary vein isolation procedure") for atrial fibrillation, patients have to undergo a re-do procedure in an attempt to assure that no residual connections between the pulmonary veins and the left atrium have become re-established and re-initiated the person's atrial fibrillation.

The above figure is an example of recordings taken on a re-do ablation procedure in a patient with recurrent symptoms despite a prior atrial fibrillation ablation procedure. The signals were recorded come from a series of catheters (wires) in the heart as shown:
The "basket catheter" is actually an 8-splined catheter with 8 electrodes per spline and is shown here:
Now, with all of those wires in the heart, we can record signals from all of them simultaneously and display them on a computer. An example of the recordings taken from all of these wires is shown here (click to enlarge):

Now, most of my cardiology colleagues get glassy-eyed when they see these tracings. But for the electrophysiologist, they can be heaven! Here's what this series of tracings shows:
  • The top three lines represent different signals from the surface electrocardiogram (EKG). These surface signals are a portion of what your doctor sees when an "EKG" is performed so he (or she) can understand what's going on electrically in your heart. But beneath the first three lines is MUCH more...

  • The next two lines have signals recorded from the right atrium, where the normal heart beat starts for two consecutive heart beats.

  • The next two lines represent the signals from those two heart beats recorded at the AV node - the electrical connection between the right and left atrium that electrically connects the upper atria to the lower ventricles.

  • The next five lines are signals obtained within the coronary sinus (a vein that lies along the left atrium) at varying intervals proceeding from right to left.

  • The next 16 lines are signals obtained from the basket catheter positioned into the left upper pulmonary vein. Note that there is a series of six closely coupled signals that occur very rapidly and have no association with the activation in the left atrium (those in the coronary sinus) nor the surface electrocardiogram (EKG). This clearly demonstrates that the left upper pulmonary vein is "disconnected" (or "isolated") electrically from the rest of the left atrium. Hence, although this person's pulmonary vein is occassionally having rapid electrical firings within the structure, it can no longer perturb the remainder of the atria and this patient will be clinically "cured" from atrial fibrillation.

While we were happy to find this during our repeat ablation procedure, we mapped the other pulmonary veins and discovered the right upper pulmonary vein had re-established an electrical connection. Isolating that pulmonary vein rendered this patient arrhythmia-free.

Man, you gotta love this job!


Addendum: 17 Feb 2007 @ 0830 CST: This morning I saw this video demonstration over at Kidney Notes and I could see the future of atrial fibrillation ablation...

1 comment:

View from the Trekant said...


"Now, most of my cardiology colleagues get glassy-eyed when they see these tracings."

Sad but true. We rarely get to see a good EP case at our weekly cardiac case conference. The surgeons actually boo when they see EP tracings!

As a cardiology fellow I was in on a successful WPW ablation. I felt a light go on when it was clear that there was no more pre-excitation. Cool! But I can't sit in a procedure for 3 (or 5 or 7) hours the way you guys do.

EP is the endurance sport of cardiology.