CNA Conference - Dr. John Clark - A case of CNA for Long QT Syndrome

Um, we're gonna move on for time's sake here. Uh, Doctor Clark, uh, Doctor Clark's next discussion here. Is a case of CNA for long QT syndrome. Uh, I appreciate the opportunity to talk to you. I want to talk a little bit about cardio neuroablation and Anderson Tawil syndrome. Anderson Towel syndrome is a rare genetic defect. Um, which causes a triad of dysmorphic faces, periodic paralysis, and ventricular arrhythmias. It is also known as long QT type 7. Um, it is genetically inherited, and the only defined gene so far is a potassium channel gene defect, KCNJ2. Um, aside from the dysmorphic features. Um, one of the hallmarks of Anderson-Til syndrome is they're often frequent, but asymptomatic ventricular ectopy. The patient I want to talk about. Uh, was born in 2014. She has two brothers, a father, a paternal uncle, and paternal grandmother, as well as a paternal cousin, all who are genetically positive. Her paternal uncle was the index case. He was diagnosed after cardiac arrest. Um, The patient currently under discussion, uh, had a large VSD at birth. And that subsequently spontaneously closed. Via tricuspid valve tissue ingrowth. She also has a left SVC. In addition, she had PVCs noted at birth. They were fairly frequent early on, about 5 to 10% in the early months of life, but decreased down to less than 1% over time. She had been maintained on a beta blocker, um, and in January 2018 at 4 years of age, she had a syncopal event 5 minutes after vaccination. Uh, she was standing in the primary care's office at the checkout counter and. According to Mom, became rigid and fell over. She had loss of consciousness for about 30 seconds. No vitals or rhythm were documented with this event. She suffered no injury, and in talking to her afterwards, she had no prodrome. Um, parents, uh, state that she had been compliant with her beta blocker therapy. After discussion at that time, she had a loop monitor implanted. And then in November of 2018, she had another syncopal event again after vaccination. Um, the loop monitor. showed a 6 2nd asystolic pause followed by a short run of VT around 280 beats per minute. This is her loop monitor recording. You can see her heart rate slowing, slowing, and then from here, she's asystolic until here, and then it terminates with about a 7 beat run of VT. Of note in the family, the paternal uncle had a cardiac arrest at 15 years of age. He was successfully resuscitated. Paternal grandmother also, uh, had a successful resuscitation from cardiac arrest, and so the family is quite familiar with the consequences of the disease. And after a lot of discussion, um, a decision was made to implant an ICD. The benefits of the ICD are twofold. One, it can pace her to avoid the bradycardia induction of her tachycardia, and two, if she does have a VT event or torsos, it could terminate the event. Um, at that time, she's 12.4 kg. This is what an ICD implant looks like in a 25 pound child. Um, as you can see, we have an SVC coil positioned high in the mediastinum. And we have a subcutaneous coil positioned low in the lateral thorax. Her generator is sub rectus midline abdominal, and then she has epicardial pace sense leads on the RV free wall. The shocking vector here works very, very well in children who need an ICD and actually get shocked from an ICD. This is an exceptional vector to use. She did well after that until 2022 on routine device interrogation, she was found to have complete loss of capture on her RV lead. Um, at any output. Therefore, we cannot rely on pacing anymore to prevent her bradycardia. She still had sensing intact, so she still had therapy options of ICD shock if needed. At that time we discussed possible CNA with the family, and the decision was made to proceed with that. Some of the confounding factors in her case that are her small size, she was 16.8 kg at the time. She was too small to make the grid catheter a reasonable option. Also, uh, I did not use an irrigated tip RF catheter. In addition, her left SVC adds an added dimension to her anatomy. This is her geometry is drawn by our insight system. As you can see here. Here's her SVC entering right atrium, IVC down here, tricuspid valve, left atrium back behind, right pulmonary veins here, left atrial appendage, left pulmonary veins here, and her left SVC is coming in behind and entering through the coronary sinus this way. Looking at an LAO view, you can see the, Left SVC coming in behind the left atrial appendage. Looking from purely behind, you can see the left SVC coursing down into the right atrium through the coronary sinus and. Right sided SVC here. We did a fractionation map, which you can see also the line of blue dots here and here are all the areas that we could capture the phrenic nerve. Uh, I haven't shown that in all of my, uh, slides today, but in every patient, we do map out meticulously the location of the phrenic nerve so as to avoid it. Um, looking in an AP and lateral view, she had. Target areas in GP site #1, GP site #2, GP site 3, and GP site 4. Looking from behind. What you can see is we did deliver lesions. This is GP site number 4 here, but we could map it from both sides. So left SVC, we mapped it from within the left SVC and these two lesions from within the left atrium. So we attacked GP site number 4 from both sides, GP site number 3 from within the mouth of the coronary sinus, GP site number 1, and GP site number 2 here. And again, all the areas that we're avoiding from a phrenic nerve standpoint. She did very well. This was her pre-ablation vagal response to extra cardiac vagal stimulation. And then when we're all done, this was her post ablation, vagal nerve stimulation with no change in heart rate, so we had a, a very good response and no response to atropine at the end of the case. Um, so we're very happy with, with how things ended up. Following her over time, oh, sorry. This was her EKG pre ablation, um, with some sinus arrhythmia. You can see that her T waves are sinusoidal with an upslope and a down slope. Um, before baseline, and with her sinus arrhythmia, her correct EQT wanders fairly dramatically across the page, but a significant QT prolongation. This was her EKG immediately post ablation. Um, and this is her EKG one year post ablation, so her T wave anatomy is pretty much back to what she was pre-ablation, but she's lost her sinus arrhythmia. In January of 23, she received a vaccination again, uh, this time without pacing and without syncope. So that was very gratifying that we could get by through that, but she could not pass out for a whole bunch of reasons. So, what other information do we have from her case that would help us say, no, we really did make a difference in her? Um, one of the things is through her ICD, because her sensing is still fine, uh, we can look at her heart rate trends. And her procedure was September of, late September of 2022. So, this is a 14 month trend. You can see her nighttime and her daytime heart rate trends over the last 1213 months before the procedure, and you can see on the day of the procedure, boom, things shoot up and her daytime and nighttime heart rate both increase. OK. Um, but how does that, Continue over time. Here we are 6 months post procedure. Again, you can see the average heart rates day of the procedure and then the average heart rates thereafter. And then 12 months post procedure that increased. Daytime, nighttime and daytime heart rate trends have persisted. So this speaks pretty well, at least to the short term durability. Um, of the procedure, even though we didn't use the grid catheter, even though we didn't use irrigated tip catheters, um, at one year post procedure, her day and nighttime heart rate trends remained elevated. Um, similarly, we can track through her device, her heart rate variability, and so here's her heart rate variability for the last 1213 months prior to her procedure, and then you can see the day of the procedure, boom. The heart rate variability diminishes. 6 months later, heart rate variability has stayed low, and 12 months post procedure, her heart rate variability has remained low. So both of these speak to the potential durability of CNA in pediatric patients despite the tools that we have to use. Looking at her PVC counts through her ICD, um, on the day of her procedure, the interrogation showed for the last several months prior to the ablation, 16 PVCs per hour. Um, when we looked at 6 months and 12 months, Post procedure, her PVC counts remained less than 0.1 per hour, so a significant decrease. Um, you know, in actual number, that's very small, but when you, if you look at it in percentage, um, that is a more than 98% decrease in PVCs, uh, on a daily basis, and that has persisted for a year. So, in summary, CNA may offer an important tool for treatment of bradycardia induced tachycardias. The prime example there would be long QType 3 and possibly Brugada syndrome. Um, it may also add one more treatment option in the care of difficult arrhythmias common in Anderson Towel syndrome. If anybody has had, The struggle of caring for patients with Anderson-Twel and ventricular ectopies, they can have 50 to 80% ventricular ectopy incessantly all the time, and it is notoriously difficult to control. So if CNA offers a potential option, it would be a welcome treatment tool down the road. Um, I'm going to finish up there and open up with any questions or suggestions. Please reach out to us at heartbeat@ Akronchildren's.org. Thank you very much. Thank you, Doctor Clark, very informative, uh, presentation. Uh, our first question here comes from Javier, uh, Branches. Um, he's asking about, uh, everyone using longer lesions. Periods of time like Doctor Reddy uh describes. Have you found that standard ablation targets such as impedance drops or ablation indexing, uh, are useful and effective tools? In children, I don't use irrigated tip catheters and My approach is different when I'm not using an irrigated tip catheter. I'll set my power at uh 60 watts, sorry, 50 watts and a temperature of 60 degrees. Um, and I typically do a lesion for one minute. Um, and, but in really small kids, I'll cut it down to 30 seconds. Um, and then I am looking for impedance drops, but I, I follow that much more closely when we're using an irrigated tip catheter with the, with the young adult patients. Yeah It is a very important question because uh obviously the for cardioversions many times or most of times we are doing procedures in normal people so we have to take care about the, uh, the amount of lesions and the depth of the, the lesions. So, I think he, uh, probably the, there is a tool that helps a lot, that is the vagal stimulation. So, if you do the ablation and there is vagal responsive, we may advance it a little bit more. But if there is no more vagal responsive, we may stop the procedure without more deeper lesions. So I think the control by the vagal stimulation may be helpful. And I would like to Congratulated the, the team, uh, John, Stephan, because this uh wonderful and amazing case what we just saw uh was performed without Xx-ray and without irrigation. It's, it's very important to say this. So in, with, uh, the most conventional way to, to, to do the ablation. However, obviously, without X-ray by using the electroatomic mapping, but it, it was possible to get a wonderful uh result, wonderful outcome and help the patient. I, I have a healthy respect and at the same time fear of irrigated catheters because I I'm not looking for that increased depth of lesion in most of my patients, and, uh, you know, I've, I've always thought that if I felt I needed to go to an irrigated tip catheter in a pediatric patient, it was because I was mapping things wrong. Yes, and I, I think that's almost always true. Yes, in, in, in, in cardio ablation, I have a lot of times patients with low BMI, so we have to take care about the lesions. So, I, I don't know what the age or the size cutoff is, and, you know, when should I really start thinking about, OK, I'm going to use irrigated tip, but right now, if, if you're younger than 18, I don't use irrigated tip. If you're obese and younger than 18, I probably would, but uh in most instances, I choose not to. OK.