There is a Place for Both Single-Shot and Focal Pulsed Field Ablation in Your Ablation Practice: Interview With Anthony Moretta, MD
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EP LAB DIGEST. 2025;25(3):1,7-11.
Interview by Jodie Elrod
EP Lab Digest talks with Anthony Moretta, MD, from Heart Rhythm Consultants, PA, in Sarasota, Florida, about his experience with the PulseSelect™ Pulsed Field Ablation (PFA) System and Sphere-9™ catheter (Medtronic), including how he decides which technology to use and when, updated workflows, and how the introduction of PFA has influenced his clinical practice.
What are the biggest differentiators between the PulseSelect™ and Sphere-9™ catheters?
One of the most obvious differentiators is the dual-energy capability of the Sphere-9 catheter. A primary advantage of PFA is safety. I think a lot of the transition to PFA is fundamentally driven by the pursuit of enhanced safety, specifically mitigating the risks of complications such as atrioesophageal fistula (AEF) and phrenic nerve paralysis. While these complications are rare, they are devastating, so that underscores the importance of minimizing their occurrence. So, when shifting to a new ablation modality to prioritize overall procedural safety, one of the potential concerns is using PFA in scenarios where radiofrequency (RF) has demonstrated robust safety. The Sphere-9 catheter allows operators to use RF ablation in cases where the overall safety profile using RF has been well established. So, I think that is the most important differentiator. When it comes to doing certain flutter ablation lines, for example, traditional use of RF was effective and safe, and we should continue using RF. While there is nothing wrong with using PFA, the technology is new and I would like to see it be used more and the safety profile be more well adjudicated prior to shifting to PFA in those instances.
Another big differentiator is integrating mapping and ablation. By integrating both mapping and ablation with the Sphere-9 catheter, we limit catheter exchanges, and in doing so, we can reduce the risk of air embolism. Even if PFA was not available and the Sphere-9 catheter came out as just an RF catheter, I think that it would still be the primary catheter I use. This is because, even among all the RF catheters that are out there, it is the only one that can high-density map and ablate. Because the Sphere-9 catheter is capable of high-density mapping, we can do everything with one catheter.
Another thing that I think is important is reduced vascular access complications. The Sphere-9 catheter is compatible with smaller sheaths like an 8.5 French (F) sheath, whereas some single-shot PFA catheters are 14F or 17F sheaths. In general, when you use bigger sheaths, you are more prone to getting vascular complications such as larger hematomas, arteriovenous fistulas, etc. By using a smaller sheath, one can mitigate these complications.
A great feature of both the PulseSelect catheter and Sphere-9 catheter is their precision and limitation to collateral damage. I became a
PulseSelect catheter user primarily because I thought it was the most precise single-shot catheter. It also limited collateral damage. With other single-shot technologies (and this is part of the nature of PFA as well), operators can ablate tissue outside of what they intended to ablate, such as isolating the posterior wall or, even worse, causing an isthmus along the posterior wall that can be a substrate for flutters. As a single-shot catheter, the PulseSelect catheter does a great job of limiting any collateral ablation that was unintended.
I am a big proponent of fluoroless ablation, so we do not wear lead in my lab. I do not use any fluoroscopy with the PulseSelect catheter unless a patient has a device or there is some sort of extenuating circumstance. I have always done fluoroless RF ablation and it was relatively easy to transition to fluoroless PFA ablation with the PulseSelect catheter. With the PulseSelect catheter, you can use traditional mapping systems to visualize catheters, put a decapolar catheter in the CS like you are used to, and then do everything fluorolessly. I do use the Sphere-9 catheter without fluoroscopy, but in those cases, I do not put the decapolar catheter in the CS. I tend to put it in the high right atrium and use intracardiac echocardiography (ICE) to visualize the catheter. So, I point the ICE towards the superior vena cava (SVC), advance the decapolar catheter to the SVC, pull it back a little so it spans the SVC and crista, and then leave it there. I do that in cases where I suspect only pulmonary vein isolation is needed.
How do you decide which technology to use and when?
When it comes to deciding to use the Sphere-9 catheter or PulseSelect catheter, left atrial size and whether I plan to isolate the posterior wall play a role. So, in patients with persistent AF and at least moderate left atrial dilation where posterior wall isolation is anticipated, the PulseSelect catheter is my preferred catheter. It moves around easily and the precision is very impressive. It is important to note that even though the PulseSelect catheter is precise, the catheter is rather large (25 mm) because it is a single-shot catheter. So, in smaller atria where I want to spare the posterior wall, if the patient has a small body habitus, I prefer the Sphere-9 catheter. I also choose the Sphere-9 catheter if I am going to ablate the cavotricuspid isthmus (CTI), and this has a lot to do with cost. If I am going to ablate, I might do a mitral annular line as well. Mitral annular line and CTI lines are not only a little more difficult with the PulseSelect catheter because of the size of the catheter, but there has not been enough data for me to feel comfortable doing CTI lines with PFA. Instead, RF ablation is tried and true and very safe in those circumstances when we are doing flutter lines. With the PulseSelect catheter, if I induce a left atrial or typical flutter, I will pull out another ablation catheter—I will not ablate it with PFA. Now, this can be subject to debate. But for me, if we are trying to make a procedure safer for those patients who experience AEF and phrenic nerve injury, what is the point in offsetting it by adding risk? I can bring out another catheter, but that adds cost to the case. So, with the Sphere-9 catheter, I can minimize cost without compromising safety.
Can you describe the workflows that you have developed with the PulseSelect catheter and the Sphere-9 catheter? What visualization techniques do you use? Can you describe the catheter and sheath handling?
The catheter maneuverability has been great with both catheters. The workflows for both catheters are similar, but there is some variation. The first is sheath exchange. The PulseSelect catheter requires an additional catheter exchange from an 8.5F mapping sheath to a 10F sheath. That is my workflow because I use high-definition mapping. I do not map with the PulseSelect catheter. When I graduated in 2014 as an EP fellow, I saw the progression of mapping with less points versus high-density mapping, so I think it adds significant value. I put in an 8.5F sheath, go transseptal with that, map with a high-density mapping catheter, and then I will exchange for a larger sheath like the FlexCath Contour (Medtronic), put in the PulseSelect catheter, and ablate. Then, I take the PulseSelect catheter out and map again with a high-density catheter. That sheath exchange is minimized with the Sphere-9 catheter, so I do not have to do that because the catheter can perform both high-density mapping and ablate.
In terms of sheath management, with the Sphere-9 catheter, I can use a reliable sheath that has been around for a while. It performs well with the Sphere-9 catheter and allows for smooth catheter maneuverability. It enhances system flexibility because the catheter itself moves well and the operator can rotate it, bend it, and get it anywhere, but the ability of the sheath to move as well or to be deflectable also helps. So, you can use multiple different deflections, whether it be in the sheath or the catheter, to get to where you need to be in the left atrium.
How does having 2 options for PFA/RF affect your choice in ablation energy source going forward? How has the introduction of PFA influenced your practice?
The ability to have 2 different PFA or RF platforms represents a significant advantage in the landscape of AF ablation. Each catheter has unique advantages suited to specific clinical scenarios. So, while we acknowledge these distinct applications, right now I use PFA for all my AF and flutter ablations. It has really changed my practice a lot. Being able to use one or the other catheter depending on left atrial size or expected ablation of extrapulmonary targets has given me more versatility and enhanced safety. I think the most surprising thing with PFA is how quickly the patients recover. When we did RF, especially when we had to do a lot of RF ablation, patients generally did not feel well for a while afterward. However, with PFA, it has been remarkable. We could do a posterior wall, do the veins, and then if we have to do flutter lines with RF or the Sphere-9 catheter or if we have to take out another catheter and use the PulseSelect catheter, the RF application is minimal, and these patients recover remarkably well. They wake up and no longer have chest pain, pericarditis, or gastroparesis like they used to have. Overall, they feel better after the ablation and there is much less development of post-surgical sequelae.
What advice would you give to a physician who is about to choose a PFA technology?
I was lucky enough to be able to use most of the PFA currently available because we work at an institution that is supportive of new technology and helps us have the best available technology for patient care. My number one piece of advice is to prioritize safety. Do not forget that the fundamental principle driving the electrophysiology community’s enthusiasm for PFA is enhanced safety. Clinical experience has shown significantly faster patient recovery with PFA, and this is probably attributed to what I call the “gentleness” of the technology. It is not as harsh as thermal ablation, whether it be cryoablation or RF ablation. So, I would strongly encourage physicians to prioritize and enhance safety. Do not forget this is why we adopted PFA in the first place. Sure, we found other things that are great about it, but you can take any good technology and make it unsafe, whether it be ablating too much because it is easy or ablating areas that you should not be ablating or that can add inherent risk.
Also, invest time in technology. If you are lucky enough to evaluate the different PFA platforms, dedicate enough time to each one of them. You might initially find that one is easier than the other, but if you take the time and really stick with all the technologies, you might be surprised at which catheter is preferred after using it a good amount of time.
In addition, PFA is new, and in a lot of the landmark trials, they did not use comprehensive high-definition mapping. I think that whenever we use a new technology, we should be wary or cautious to let go of things that we know work well. So, maybe in the future, using PFA will mean that we do not need to map at all. But we do not know that yet. So, I would advocate for pre- and post-ablation mapping in all cases. Even if we find we do not need it later, it gives us a lot to learn from. When you map before and after, you can see different things. For example, I tend to have a difficult time isolating the right inferior pulmonary vein and there tends to be a point where I get reconnection or do not get first-pass isolation. So, I think pre- and post-mapping in the nascency of the technology is important. In my experience, post-ablation mapping frequently reveals insights that refine the initial lesion set. A lot of times if I just ablated and did not map afterwards, there would be a lot of gaps that I would not know about. However, with post-ablation mapping, I see those gaps and can focus more on those areas that might be troublesome, which leads to more effective ablation and more common first-pass isolation.
The transcripts were edited for clarity and length.
Disclosure: Dr Moretta has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. He reports consulting fees, research, and participation on an advisory board for Medtronic; consulting fees, speaking, research, and participation on an advisory board for BIOTRONIK; consulting fees and preceptorship for Boston Scientific; and consulting fees, participation on an advisory board, and research for Johnson & Johnson MedTech.
This content was published with support from Medtronic.
