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EP on EP Episode 103: Differences in Ablation Ener ...
EP on EP Episode 103: Differences in Ablation Ener ...
EP on EP Episode 103: Differences in Ablation Energy Sources
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Video Transcription
Hi, I'm Eric Prystowski. Welcome to another segment of EP on EP. Today I have a buddy of mine for many, many decades, and that's unfortunate, right? It is. Sad to say. Sad to say. Dr. David Haynes, who's currently the director of the Heart Rhythm Center at William Beaumont University Hospital. David, welcome to the show. Thank you. Thank you for having me. I know you're shocked at this, but I'd like to talk to you about energy sources and ablation. Something you kind of... I've heard about that. I figured that. Yeah, yeah. So we have all these new toys. Right. And I know it's not fair to call them toys, but can you maybe do a quick rundown of what's available and what your thoughts are? So in terms of legacy ablation energies, of course, RF is the big daddy. It was there 40 years ago. It is still here, proven the test of time, highly reliable, but there are issues. We have cryo ablation. We have laser ablation. These are all thermal ablation technologies, and they all work by freezing, by heating, and they're all fairly predictable. But the concern about thermal technologies is collateral damage. And we all lived through the era when contact force sensing was introduced, and we were pushing those RF catheters into the posterior left atrial wall, and all of a sudden, atrial esophageal fistula was showing up with dire results. So we now have pulse field ablation, and it's taking the field by storm, but we don't have an approved system yet. So all we have is a limited number of patients from investigational studies, and we'll see how that turns out. So since PFA is the ablation du jour, right? Right. I agree. It is. So when I was at one of the meetings, the AAF meetings a few months ago, I was surprised to see the Europeans were presenting data, and it seemed like each system was a little different. So can you tell me a little bit about that, and does that mean that you have to learn your system? Right, right. Why is that? So we're used to RF, which has a standard waveform that creates heat. So it's just essentially like a soldering iron when you get right down to it. Pulse field ablation, the biology of it is very complicated, and the parameters that are adjustable in a pulsed wave delivery include amplitude, pulse duration, pulse number, pulse interval, number of pulses in a train, number of trains in a delivery. All of these things are highly proprietary, and we don't know one system versus another. And that really has led to, I think, kind of an untenable situation where researchers cannot compare commonalities between systems, because if you've got one delivering nanosecond pulses and other microsecond pulses, it's a huge difference. And also, you know, as with, you and I have been through this for years with these systems, and there are always unexpected complications that come up. I think with the PFA, all this coronary involvement that I don't think anyone ... Which wasn't anticipated. Right, because it was supposed to be specific for a certain type of muscle or tissue. So you have thoughts on what else we have to worry about that hasn't been looked into? So to expand a little bit on that, there was a very disturbing case report of a circumflex coronary artery spasm when pulse field energy was delivered on the mitral annulus in close contiguity to that artery. Turned out it was reversible, there was no infarct, patient did okay. There's been subsequent work in animals and a small series in humans where it's been reproducible that you get coronary spasm when you're too close to an artery with your delivery catheter. Now, the good news is that nitroglycerin does seem to mitigate this to a great degree, and the recommendation is to initiate a nitro drip if you are ablating in that close vicinity to the artery, but there are unknowns. What happens if a patient has coronary artery disease? So do abnormal coronaries respond the same way? Can you get showers of emboli with distal small vessel infarction after the spasm? So I think that that is a potential concern that we don't know. And there's an interesting other concern the other way. I'm not a big believer, although I'm still awake for the data, that you need to get rid of the ganglion plexus. That's part of why we win, right? So I've heard some people very concerned say, you know, this technique doesn't affect the nerves. So are we having sort of an unintended opposite reaction? But of course we don't know if that's really true, right? So, well, so first of all, you can damage nerves with pulse field, but it's a dose and proximity related response. So they are less sensitive to injury than they are to thermal techniques. But the ganglion plexi, they don't seem to be affected much by pulse field, and I think time will tell. I think, you know, is there going to be a point at which we flip the switch to a thermal technique in the middle of a pulse field pulmonary vein isolation, doing GP mapping to try and get those? Is that necessary if we're getting high success rates without GP involvement? You know, maybe that's good enough. I think, you know, there are unknowns out here. I think it's a good point you raised, David. If you look at the early results that have come in, the success rate is not strikingly different from RF. I mean, it's in that usual 65, 75 bandwidth, and we know we're not getting rid of the ganglion plexus. So that would be a little maybe on the, I mean, no one knows for sure, but that speaks a little against the fact you have to knock out the ganglion plexus, right? Right, right. And the other thing about pulse field that I have stated inaccurately in earlier days of the technology, that contact is not important, well, contact I think is important. So I think that some of the less impressive success rates that are coming out now may be a fact that, virtually the fact that the catheter is not really pressing into tissue. It may be just kind of bouncing off the surface. And when you do that, a lot of the voltage gradient kind of goes into the blood and there you can get, you know, a 20, 30% drop in voltage gradient in the tissue when you're not in good contact. Okay. So we need to learn more, and we need to have more systems out there in more hands. And will they ever be in a head-to-head comparison, you know, because every one is different. Right. And that brings in a whole new complexity. That's unlikely though, right? Right, right. So let me end with some thoughts from you on the fact that everything done now, expectedly so has been PVI. Right. But we both know that there are areas that you have to attack in different patient groups that are not PVI. Right. Other than success or failure, do you anticipate any potential unexpected complications if you're going after like a left atrial appendage or an SVC that haven't been looked at? What are your thoughts on that? So I do think that there are certain areas where the kind of lack of controllability of PulseField will preclude its use, like in particular close to the AV node. Okay. I think one big potential risk is because PulseField is so fast and easy, some operators may be inclined to just keep ablating. And we talk about the so-called red atrial syndrome. That is to say the voltage map post-ablation shows no viability. Yeah. That's not necessarily in the patient's best interest. Yeah, I hear you. David, it's been a wonderful discussion. Thanks so much for joining the show. Okay.
Video Summary
Dr. David Haynes, director of the Heart Rhythm Center at William Beaumont University Hospital, discusses energy sources and ablation techniques with Eric Prystowski. They compare legacy RF ablation technologies with newer options like pulse field ablation, highlighting the importance of understanding system specifics for optimal outcomes. They address potential concerns such as collateral damage, coronary involvement, nerve effects, and the need for further research and system comparisons. They also touch on the challenges of targeting areas beyond pulmonary vein isolation and the risks of over-ablation. The conversation emphasizes the complexity and ongoing developments in cardiac ablation procedures.
Keywords
cardiac ablation
energy sources
ablation techniques
RF ablation
pulse field ablation
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