New Technologies for Atrial Fibrillation Ablation

One of the highlights of the Heart Rhythm Society 2008 meeting in San Francisco was the “EP TV” live cases performed today. In the morning were two ventricular tachycardia cases, and the afternoon, two atrial fibrillation ablation cases. They were professional and very well-attended.

One of the more interesting interactions occurred in the afternoon atrial fibrillation case discussions which included doctors Warren M. “Sonny” Jackman, MD (Oklahoma City, OK), Fred Morady, MD (Ann Arbor, MI), Andrea Natale, MD (his lab was operating – Austin, TX), Douglas Packer, MD (Rochester, MN), and Koonlawee N. Nademanee, MD (Inglewood, CA) as panelists and John D. Day, MD (Salt Lake City, UT) as moderator. There were two paroxysmal atrial fibrillation cases being performed – one with manual catheter manipulation and CartoSound ultrasound image development, and the other using the Hansen robotic mapping system coupled with the ESI Nav-X 3D mapping system that used their new “Fusion” software to superimpose a pre-procedural-obtained CT volume rendered image over the Nav-X geometry.

I have attempted to paraphrase the commentary (taken from notes taken) in response to a question e-mailed to the participants from the audience:

“What does the image overlay and all of this technology add to doing this procedure?”

Jackman: Well, with the known limitations of registration with these systems, I am cautious when using them. CartoSound is okay, because you’re imaging the surface of the heart directly. And certainly pre-operative CT imaging is helpful to understand the anatomy. But I would have wanted to get a feeling for this arrhythmia first (the patient was in sinus rhythm at the time) – I would want to initiate the rhythm first to see if there might be something I might understand to ablate before proceeding with the whole afib ablation. I might not find anything else most of the time, but if I did it’d be helpful.

Nademanee: I just use Carto to create a very simple map – you know, the His, CS, and pulmonary veins and use about 6-7 minutes of fluoro for the whole case after the geometry is developed – I don’t think Stereotaxis would help reduce that time very much. I use image guidance with fluoro, because my technique uses electrograms and I’m going to move that catheter because my technique relies on proper electrograms.

Morady: I don’t think there is a dispute over the role for 3D mapping of the left atrium – it cuts down on fluoro, and registering the locations of the ablation points is helpful. The extra imaging with “Merge” and CartoSound is nice but it could be that a mistake if 1-2 mm will be the difference between thinking you’re in the left atrial appendage or the ridge outside the left superior pulmonary vein. We still need a cost-benefit evaluation. Will outcomes be better? I don’t know. In the top labs around the world, they’ve ben doing a pretty good job already – it’s hard for me to think it’ll be improved with this technology.

Day: Andrea, tool or toy?

Natale: In the hands of people who do this everyday, it might not be that helpful, but for people who don’t do it everyday, I think it will be useful.

Packer: I agree with Fred’s (Morady) comments. In the more complicated cases, the utility of 3D images increases our success we think. We’ve done validation (on accuracy) with CT images. CT’s are yesterday’s news, ultrasound is today’s. Ultrasound gives about a 2mm error, vs. 3D mapping systems that give 6-8 mm error. How fast can we do it? How much does it cost. We’ve found we’re doing less pre-procedure CT’s with ultrasound now… The utility of all of this will need to be sorted out in prospective randomized trials…

Hopefully this will give a flavor for their enthusiasm. Consider purchasing the actual CD for the actual conversations from the Heart Rhythm Society if you’d like to hear more…

-Wes

Addendum: The funniest moment of the whole event was when Rodney P. Horton, M.D was introducing his atrial fibrillation case. Imagine, a room the size of two or three football fields full of cardiac electrophysiologists from around the world, analysts from every major venture capital firm in this space, and tons of industry personnel - all whom have collectively performed thousands upon thousands of catheter ablation procedures for atrial fibrillation. Then Dr. Horton says:

"...atrial fibrillation is an experimental procedure and is not approved by the FDA..."

and there, lying on the table is a patient with a Hansen robot in their leg (approved by the FDA) and an ESI mapping system (approved by the FDA) mapping their heart.

The whole room started quietly chuckling...

...like anyone cared. Now, it seems, every operation performed in the US will have to be "approved by the FDA" before it can occur.

-Wes