Friday, February 24, 2012

Teaching Old Dogs

I guess I've now become an "old dog" in medicine.  The residents look younger, the fellows, sharp and trim, and some of my contemporary physicians, like well-worn time-pieces, are beginning to complain of sore knees, backs, and declining vision.  And then there's the nocturia...  


But for those of us who've been around the block a bit, there remains the constant desire to remain up-to-date, novel, even original.  So we try new new things.  Sometimes they work for us, sometimes they don't.  One thing's for certain, however, it's much harder for salespeople to sway us old dogs, because by now, many of our habits are based on past experiences, not press releases.

Take for instance, three-dimensional mapping in the EP lab.  It's cool stuff: electrodes or magnets are arranged around the patient to create an X, Y, Z coordinate system of sorts, and a catheter is moved about inside the coordinate system to locate structures, map arrhythmias, and to facilitate movements of catheters without x-ray guidance.   The pictures are multicolor and stunning.  They are also typically studded with little circular dots placed in locations chosen by a technician to look stunning.  Sometimes, this technology makes a critical difference in the outcome of a case.  Other times, it's probably a waste of money, since some arrhythmias are defined by very well-defined anatomic locales whose need for precisely localized ablation lesions are simply not necessary.

So I was surprised to hear one industry rep remark that "every" new fellow uses 3-D mapping systems these days to ablate anything.  Maybe he was selling his system, maybe not.  But I wondered:  Really?  Even for something as straightforward as a typical atrial flutter ablation?  "Yeah," he said.  "They don't know how to map the old fashion way like you (older) guys do." 

Maybe that's a good thing. Maybe not.  There's much more to successful ablation than locating a catheter in three-dimensional space or placing a dot on an artificially-created geometric surface.  Yet these days, I rarely hear people speak about catheter stability, injury current, unipolar electrograms, or polarity reversal any more.  Instead, when using these 3-D mapping systems, catheter ablation it sounds more like a game of connect-the-dots: "You've got a gap over there."

So too, with our ablation technology. 

This week I finally broke down and tried irrigated ablation catheters for ablation and my experience?  Underwhelming.  There was extra tubing, a stiff catheter, fluid burdens I never had to think about before, and an inability to have any surrogate for catheter contact (such as tip temperature).  In return, I received only a promise of larger lesions, simpler ablation before the case started yet found myself struggling to complete a relatively simple procedure.  Certainly there was plenty that was new and unfamiliar: new catheters, new technology, new anecdotes to remember.  But at the end of both cases I performed, I found myself moving back to a conventional non-irrigated ablation catheter to achieve success.    Needless to say, this ol' dog wasn't impressed.

Now I know there are irrigated ablation catheter proponents out there.  They sing its praises and wouldn't perform catheter ablation with anything but this technology.  But I wonder how many of them ever looked at the physiology of what they're doing.  Years ago, I performed sinus node ablation in dogs with 50 watts of power using an 8mm tip conventional radiofrequency ablation catheter equipped with temperature feedback.  I saw what that much energy did to the dog's heart... and surrounding lungs.  I will never forget that finding.   My practice in man was forever changed as a result of that opportunity.  I find it hard to believe we need more energy than that if there is good catheter contact.

And yet, I now see FDA-approved 100-watt RF generators now and irrigated-tip ablation catheters capable of creating steam pops deep in tissue while having nice cool endocardial tip temperatures displayed that provide an artificial level of reassurance to our younger operators.  I know there's a reason these technologies were developed: influential doctors in our EP community demanded they be developed and industry responded.  Skill levels of operators are different. It was new and innovative.  It promised better outcomes while being acceptably safe, yet without so much as a lick of real-life multi-center case-based post-market proof.

So when I see the relatively high complication risks of atrial fibrillation reported recently, I wonder if some of those complications were from this push to higher power, irrigated-tip ablation catheters capable of making ridiculously larger, deeper ablation lesions in our rush to expedite the procedure couched on the unproven hope that with larger lesions, the need for repeat ablation would be reduced.  Is it?  Are we creating more problems than those we are hoping to solve?  Truth is: we don't know.

Which is exactly why we need an atrial fibrillation registry.  It's also why we need studies like the prospective, randomized atrial fibrillation ablation trial like the CABANA (Catheter Ablation versus Antiarrhythmic Drug Therapy for Atrial Fibrillation) trial to begin to answer such complicated questions.  Whether there will be enough data for subgroup analysis of irrigated tip ablation catheter from non-irrigated ablation technologies in CABANA remains to be seen.   But at least the CABANA investigators didn't require a particular form of energy delivery for the ablation arm of the study.  Will there be value in such a subgroup analysis?  It will depend on the numbers.

At least this old dog remains happy he can contribute to this arm of the ablation trial and hopefully remain innovative and creative in the years ahead while still practicing on the basis of my experience.

And who knows, maybe one day, we'll make catheter ablation safer for our patients as a result - you know: the old fashioned way.



Jay said...


I do AVNRT exactly the same way I did in fellowship.

Flutter is done almost exactly the same, just using a SRO sheath now and 8mm catheter. Still using duodeca in RA and quad in CS.

Wolff's are done about the same (although they're pretty rare now). Love to do all the mapping and pacing tricks from the old days.

I never really figured out 3D and never use it. I agree that it isn't needed for most of the basic stuff.

Sorry we can't reuse catheters anymore. I really wish you had a blog back then, when we still had a chance to win that fight.

I tell my patients I'm a really good ablation doctor from 1997.

I hope the hospital notices how much money I save. I'm with you. Just another old dog.


Anonymous said...

I am not trying to sell you on anything, i just want an honest answer.
We know the more we look for AF the more we see, and (if you believe) the Reveal XT does a very good job of monitoring, why is not standard procedure to implant one post AF ablation? Is there not a lot that can be learned? Wouldn't a 3 yr post ablation monitoring scheme give a better answer to success rates? Wouldn't this help determine when anticoagulation meds can be stopped?

DrWes said...

Anony -

We know the more we look for AF the more we see, and (if you believe) the Reveal XT does a very good job of monitoring, why is not standard procedure to implant one post AF ablation? Is there not a lot that can be learned? Wouldn't a 3 yr post ablation monitoring scheme give a better answer to success rates? Wouldn't this help determine when anticoagulation meds can be stopped?

If only it were this simple. You make great points - we would gather more information and might have a better understanding... but there's always a catch in our business, isn't there.

I am all for collecting this data as part of a clinical trial, where the burden of who pays for the Reveal XT is defined a priori in case an insurer refuses to pay for the device. That, to me, is ethical.

Remember that we should be performing ablation on patients who are generally symptomatic with atrial fibrillation, not those who are asymptomatic. Theoretically, a symptomatic patient should have symptoms if they have a recurrence, right? So who needs a Reveal XT in that case?

But we know its more complicated than that - many patients have more afib than they feel. Your point is an ideal follow-up scenario with a high sensitivity for recurrent afib. Unfortunately, it's also an expensive one. So we compromise. Technology now exists (iRhythm) to record every heart beat for 14 days with a patch stuck to the patient's chest. There's no wires, they drop the device in the mail, and we see what's left after our ablation. The patient's like it, and we get a very complete record for 14 days to confirm that the asymptomatic patient really has no afib.

If it perfect? No. Is it easy, affordable and convenient for the patient? Yes. And best of all: it doen't involve surgery.

Anonymous said...

As a recently trained EP (although - yikes! - I've now been out of training for four years) I'm a little appalled if you have people trying to sell you on the idea of an irrigated catheter for AVNRT or pathways - that's just nuts. Dangerous, too. But I feel likewise about using a nonirrigated system for AF or ischemic VT, where (a) your chances of getting a deep enough lesion are suboptimal even with perfect catheter stability, and (b) there's an abundance of evidence supporting a far higher rate of catheter tip char, and potentially even neurological events, with nonirrigated catheters, without even considering the documented lower success rate (resulting in rolling the dice again with the redo).

The right tool for the right job - like most people I know, I use a 4 mm for pathways and AVNRT, an 8 mm for CTI flutter (although I've been trending toward a 10 mm) and an open irrigated catheter for the LA and LV stuff.