Presented as part of the Department of Cardiovascular Surgery Grand Rounds on July 10, 2019, by Marc A. Miller, MD, at the end of this video, viewers will be able to:
Thank you very much for the invitation. My name is Mark Miller. If you haven't met me, I'm one of the electro physiologist here at Mount Sinai. I've been asked to talk about the evolving role of leaderless pacemakers in the peri operative period. These are my relevant disclosures. So first question is, what is a leaderless pacemaker? Obviously a lot of people who are not mps have not seen them. It is a completely self contained implantable pacemaker. It has a miniaturized battery which is basically what allowed them to develop it. It is single chamber of ventricular pacing only, so in the right ventricle only in its current generation communication is wireless. It's interrogated like a regular pacemaker. You put the wand over the chest. It is MRI compatible. It has an auto capture feature, meaning that the device will check itself daily to see what the thresholds are then pays above that threshold. That gives you a very long battery life. It is rate responsive. So as the patient walks it actually knows the patients walking. And so it increases the heart rate accordingly And it is 1990 smaller than conventional pacemakers. So why we're leaving this pacemaker has developed. They were approved by the FDA, the first type of the lead. This pacemaker, the micro nano stem where or the micro was approved about four or five years ago. And the reason is because the lead of a conventional pacemaker is its achilles heel. There's obviously acute complications related to implant, such as pneumothorax or pocket hematomas. Lead dislodge, mint and connection areas. You can actually not plug it in correctly, You have to go in and revise it. Chronic complications are a bigger issue, which is the continuous mechanical stress on the lead against the beating heart causes lead fractures, insulation breaks and therefore lead failure. It has a large surface areas that traverses the venus system so bacteria can attach patients at high risk for infection, can get a cardiac device, infection or endocarditis and it does affect neighbouring anatomy, causing venous occlusion, venous thrombosis, which is rare uh and try custard valve regurgitation, which is obviously relevant for this audience. So if you just compare the regular trans venus pacemakers, although we often tell patients in the office at the overall rate of complications for conventional pacemakers, less than 1%. If you actually look at the large registries for conventional trans venus pacemakers, it's actually significantly higher than that. The acute complication rate and this is all complications included, such as even, you know, minor hematoma is about 10 to 15% and chronic over the course of years is about 9 to 10% with trans venus leads And it really hasn't changed much over the course of many years. The same complications. There were 15 years ago as same complications we're having today. So what are the potential benefits of a leaderless pacemaker? This is just an example of the leaderless pacemaker next to a U. S. Dime. It's obviously quite small. There is no risk of pocket related complications because there is no pocket, there is no risk of pneumothorax because you're obviously not going anywhere near the lung, there is a lower and I would even say close to zero risk of device infection. And one of the reasons is because you get industrialization over the device itself pretty quickly after it's implanted and obviously it's a much smaller surface area, there is a lower risk of lead. Dislodge Mint with the micro device, there's a lower risk of device or lead failure because it's not a long lead and it's not having to work against the heart. Like a conventional lead, it does have a lower impact on quality of life. This has been looked at obviously if you have a young patient with intermittent you know long sinus pauses needs a pacemaker. A young patient doesn't mind something that they can't see or can't feel. But they do mind having a pocket an incision. And there's less physical restrictions post implant as other than being flat for six hours after the procedure. There's really no limitations such as armed restrictions after the procedure is over. Yeah. What are the limitations of a leaderless pacemaker is currently only available for single chamber pacing which is in the U. S. Only about 10 to 20% of all pacemaker implants. The perforation risk is the same as trans venus, meaning the incident rate is the same. But because a thicker device the outcomes are much worse. If you perforate with a thin trans venus lead, it's usually just a quick pair cardio synthesis. If you perforate with this device, it's obviously a much bigger issue that's less relevant to post cardiac surgery patients because it's pretty hard to perforate a post cardiac surgery patients, especially if they've had surgery months ago but possible. We've had limited experience with extraction. These devices fixate to the myocardial very well. And although there's a little knob there you see for extraction device, it's not the same as trans venus leads, of which we've had 20 years of extracting experience and there is a risk of vascular injury. It is a 24 french sheath device going in the venus system. This is the currently available leaderless pacemaker. There were two devices that were tested in clinical trials. One is the ST jude nano stem that was taken off the market because of battery issues. And this is the micro device, obviously a pretty small device and essentially what it is, it's just like a standard pacemaker. The batteries contained within here, there is the cathode in the anodes. So paces between these two and this is the fixation device. These are night in all times and I'll show you how they fixated a little bit. This is the fixation mechanism. Essentially what happens is is this is a sheet that covers the device. When you retract the sheath, these little time is almost like a treble hook become unsheathed and they grab onto the myocardial and that's how they stick. And when you're doing it in a trans venus implant, so you're doing it, let's say not in the operating room itself, it's attached to a little tether here. You just cut the tether and release the device. If you just look at real world outcomes for trans venus implants of these devices, it's actually pretty good. The success rate for implantation is very high. There were complication rate about 1.5%. So this is registry. This is real world stuff. There are five pair of cardio fusions and if you compare it to the initial trial, the ID, which is how they got to their FDA approval complication rates have gone down. If you compared to historical controls for trans venus systems, it's a significantly lower rate of complications. And this is just a comparison someone did between a leaderless pacemaker and a trans venus implant and they they demonstrated that all these kind of mid term complications out to 1.5 years were not present with the lead list device. So now, to the discussion of cardiac surgery. So pacemaker implantation after cardiac surgery and someone asked this question a few minutes ago, what is the incidents of complete or heart block after cardiac surgery and how many patients recover? So about 15 of patients undergo cardiac surgery will have some degree of heart block after the surgery, whether or not it's 24 hours a complete heart block or some a v block a few days later, a variety of different causes, ideologies for the heart block and that's related to how well they're going to recover. So there's direct trauma either from prosthesis, impingement, stitching or excision, there's tissue oedema, there's exacerbation of preexisting, conduction, system disease, ischemia, etcetera. But most of the A. B. Conduction abnormalities after cardiac surgery are only transient Worldwide. Basically the incidents of needing a pacemaker after all forms of cardiac surgery is about 2%. If you look at it after cabbage, it's well less than 1%. And if you look after valve surgery, especially multi valve surgery, it's about 4-6 and I think that's relatively consistent in this institution as well. But pacemaker implantation after cardiac surgery is not a benign issue, complications that we experience are mostly pocket or lead related. You can get device infection in the long term and up to 10 of patients lead fracture installation breaks and up to 15 of patients. Venus exclusive disease, which may be clinically significant or non clinically significant of 25 And lead-related. Try customer regurgitation can actually occur in up to 40 and it could be anything from mild to moderate tr Unfortunately, the CCH guidelines give almost no guidance on what to do and basically they write permanent pacemaker implantation is indicated for third degree in advanced second degree postoperative. A. B block that is not expected to resolve the decision to implant as well as the timing is left to the physician's discretion and therefore you see a lot of variability in this. In some surgeons you see want Us to put in a pacemaker of day four other surgeons want us to wait till day 12 and there's everything in between and we are amongst ourselves even kind of change our our plan every two weeks. So anyways, so what is the role of leaderless pacemaker implantation before during and after cardiac surgery? So I came up with a few scenarios based on cases that we've done here. So before surgery, you can imagine that if a patient had endocarditis, so they were actively infected and they were either had high degree of block or high risk for a V. Block and you needed to wait while the antibiotics were settling in and the patient was no longer actively backed uremic and the patient needed a pacemaker. That would be a good time to put in a lead list because theoretically the risk of having the device infected is quite low. If you put a trans venus system and someone is actively infected, That system will be infected within 24 hours. So during surgery, you think about it in patients who are undergoing a tri casted valve replacement or have a high pre op risk for developing a V blocks, such as someone who has try physical er block a baseline, you're about to do a micro and try custody. That patient will likely end up in complete heart block and for track speed valve replacement. We don't like to put any leads across the tri casted valve, a new track husband valve and neither do the surgeons after surgery. Those patients who remain in a V. Block, but it would likely eventually recover a late recovery. Late recovery can be anything out two a month patients who only need single chamber pacing and you want to avoid the need for a trans venus lead across the tri casted valve or patients who underwent a track husband valve replacement that you didn't predict would need a pacemaker. But now they do. So I'm gonna give you a couple of cases of patients that we've done here just to put this in context. So this is a 56 year old male had a past medical history of a bio A. VR. In 2013, he had end stage renal disease on dialysis. He failed to kidney transplant 2003 all dot hemodialysis patients at high risk for developing a cardiac device infection. It's the reason we don't put in primary prevention ICDs into these patients. And patient in this patient also at atrial fibrillation. Had a prior ablation and a watchman implants. We said a little bit of everything. He was admitted to an outside hospital for fever and hypertension. He ended up growing enterococcus vehicles in multiple blood cultures like eight out of 10 blood cultures. Yet T that demonstrates severe um are moderate tiara, normal aortic prosthesis and no obvious vegetation or abscess. Baseline. E. K. G. Demonstrated try testicular block which was chronic pre existing for the past few years. And he was planned for mitral valve surgery once the bacteria cleared and the plan was actually just to send him home on I. V. Antibiotics. Then bring him back in about 4 to 6 weeks for mitral valve surgery. But while he was here in the hospital he started having markedly long pauses due to high degree V. Block. And this is his baseline E. K. G. Here you can see he's got to try for secular block a wide QRS. So not surprising that this patient would end up with high degree of the block at some point. So this is a trans venus implant of leaderless pacemaker. So basically what we're doing is we're putting a sheet up into the R. A. Were crossing across the tri casted valve. And then we're injecting a little bit of conscious. Sorry, we're injecting a little bit of contrast through the tip of the catheter just to make sure that we're touching the myocardial. Um And then we kind of we'll give it a little goose neck forward tension. This is an R. E. O. This is an elio. We like to put in the septum if possible. The septum and elio is looking leftward and then we deploy the device. So here the device is actually still attached to the sheath by a tether. And I don't know if you can see this, but what I'm doing is I'm tugging on the tether to make sure that the times straighten out. So if the times are touching tissue or dug into tissue when I yank on it, the time will kind of wiggle a little bit and that tells me it's engaged. You just need to out of the four times to make sure the device is in place. And then we cut the tether and then the device. I hope so. No. Uh So at this stage you can retrieve in fact this this is the time that we use it to reposition so I can just bring the sheath back over, pull the times back into the sheet and then reposition at any time. The time you cannot easily retrieve it is at this stage here. Once I've cut the tether, so we do wait a few minutes and we do multiple tests and we tug on it a bunch of times to make sure it's not going to go anywhere and the thresholds are acceptable. Okay, So eventually he cleared his blood cultures with amoxicillin. He was discharged home six weeks later, he went an uncomplicated michael, uh replacement bicuspid valve repair and maize. I asked Percy to take pictures of lead list, but you forgot. But anyways, uh this patient, a couple of risk factors um for infection besides the fact he had an active infection, but I think it's relevant to other patients is that lead and this has been looked at. So people have actually now looked at leaderless pacemaker implants in dialysis patients. A patient population we know is high risk for infection. This was from one of their earlier registries. They had 201 patients undergoing lead. This pacemaker implant followed for 6.2 months, which is about 103 patient years. In this patient population of high risk patients, there were zero cases of bacteria mia admittedly and only a modest degree of follow up. But it is favorable. And this is a study where they actually looked at patients who got a leaderless pacemaker. Then after they leave this pacemaker went in during follow. Because they were all part of a prolonged registry. They actually developed back to re miA. They were treated with antibiotics and and interestingly none of the patients had a recurrence of the bacteria after treatment with antibiotics. And this would almost never occur with a trans venous system. If a patient has a transitional system in place to get I. V. Antibiotics. When you pull the I. V. Antibiotics off, they will just have a reinfection. Not the same case for lead lists. That's why we felt comfortable at least in this patient is putting it in despite the fact they were actively infected. So I'm going to present a case of putting it in after cardiac surgery. So this is a 65 year old male past Ministry of mitral valve replacement. In 2000 and five he had a redo mitral valve replacement in 2000 and six and then 2018 he had a redo mitral valve replacement and bicuspid valve replacement. His additional history includes a metastatic neuroendocrine tumor LV. Dysfunction in atrial fibrillation. So in this particular patient he remained in. He developed heart block almost immediately after the procedure. Um He was a physician, he did not want a pacemaker. Um but he was still in complete heart block now out to post updated 11 when we turned down the epic cardio leads and his heart rate was like 39 to 40 beats a minute. He felt absolutely horrible and he decided that it's time to have a pacemaker. So in this particular patient you can see here, you can see the trickle valve prosthesis here. So this is the R. A. O. View going into the base of the RV. This just gives a nice example here of crossing a bicuspid valve prosthesis, which I don't think it's actually been reported in the literature, but I'm sure people have done it. And this is where you see the sheath still attached to the device right at the bottom of the troika spit valve prosthesis. Just gives you a nice example in leo that you actually through the prosthesis and not through the side of the prosthesis. And this is the final implant positions family. So he was discharged three days after the lead list was implanted at follow up. He's still an intermittent episodes of complete heart block. But at this point he was mostly second degree A. V. Bach. As of july 2019. The last time he was checked, he was a ventricular pacing about 50% of the time when he was programmed to 45 beats a minute. You can see here this is an EK G1 day prior to the implant and this is about eight weeks post implant and he's mostly recovered conduction at least intermittently. At this point it looks like a long first degree of the block so he doesn't need pacing all the time. So for this particular patient would not have been a good idea to put a trans venus lead across that trickle spit valve. This is an example of a post op chest x ray after. Leaderless implant. If you've never seen one before, this is in the ap view. This is in the L. A. Of you. It's kind of coming right at you. So it's probably in the septum or the epochal septum and if you see this on a chest x ray is just an easy way to identify it in its correct location. This is another example. This is a more recent example of a case where we decided to implant afterwards. And this is relevant to a question someone asked is a 70 year old male approximately f to general Mitchell valve disease. Pre op E. K. G. Demonstrated a fib 82 beats a minute and narrow QRS. So really his only risk for developing a V. Block after surgery as he had atrial fibrillation and he was undergoing multi valve repair. Uh He got a mitral valve repair trick inspired by a true crime ways and left atrial appendage closure. On post op day three he was doing well. He went to seven west on days three through 10. He still remained in complete heart block. But if you look at his complete heart block and this is relevant to trying to predict if the patient will recover it was a junction. All escape with a narrow cure. S the vast majority of narrow curious patients do recover eventually it may be a late recovery it maybe a month or two later but usually they recover their A. B conduction. That's obviously much different if someone has a wide left or right bundle pattern. So the options at this point are you could wait even longer but he's been waiting in the house, He's also a doctor. Um you couldn't wait even longer in the hospital, but now he's like day 11 or something along those lines. He's obviously getting itchy to go home. You could discharge him home with complete heart block. You can implant to transmit his pacemaker, you can implant a leaderless pacemaker. So these are the limitations obviously been here for a while. You could discharge him home with complete heart block. But he is on the older side. It would be really hard to defend A sisterly at home. Like there are times that we send patients home in complete heart block, they're usually younger. But if you send a seven year old guy home with complete heart block and he has a sisterly at home that's almost indefensible, at least in court. Um you can implant to trans venus pacemaker. But the problem is that one he may eventually recover conduction, then he has to live with this trans venus pacemaker in this scar his entire life. And the other option is uh issue is that obviously it could affect his try to spit valve repair. So you just fix the troika spit valve. He's gonna come back a year later with moderate to severe tr Obviously, that doesn't look good. And the final options, you can implant a leaderless pacemaker. The limitation of that approach, and we have this discussion with the patient in particular was if eventually he doesn't recover his A. V. Conduction and he requires pacing, then you have to upgrade them to a trans venus system. So he's taking a small upfront risk that he eventually may need an actual regular pacemaker. So, he actually opted for option number four and he made the right decision because most patients, well, a fair number of patients will eventually recover their A. V conduction after a month Of being at home. The patients that usually required in the literature, it's about 12 of patients with complete heart block will eventually have a late recovery. I think the number is actually higher and usually the best predictor is a narrow cura so if someone has a narrow cure s with complete heart block and you let them go home with some backup pacing, it's likely that they will eventually not need that pacemaker. And this is just an example of the different types of percentages of patients who do recover. And I think although I would find this surprising, a small number of patients that are custard valves would be the ones to recover. I think that's probably because it's just direct trauma and oedema versus the other ideologies that are more advanced. His prick in the system disease and obviously myomectomy. Um And this is the impact of trans venus pacing leads on try to spit valve function after try custom valve repair. Which is that if you take patients who try to spit valve repair and they don't have a trans venus lead versus those who do more. The higher percentage of the patients with trans venus leads will have decline in their tri casted valve or incompetence over the course of multiple years. So it's best to avoid it if possible. In this particular patient he opted for a leaderless pacemaker implant. He was discharged home the next day. This is his post op visit three weeks later which was just a couple of days ago. You can see here he remains asymptomatic. He's in mob. It's one with a long pr interval and he's less than 1% RV paste. If you give him one more month he'll probably be in sinus rhythm with no E. V. Block or no long prolonged pr And then this is just the last case. This is now doing it during open heart surgery. And luckily Dr Adams team have been and doctor only have been nice enough to let us try this um during cases I don't think this has ever been reported before. Uh is actually putting the leaderless pacemaker in at the time of surgery. So this is a 39 year old female Past my country mitral regurgitation. She had a repair in 2011. She has multiple medical problems, esophageal atresia, horrible chi infosys and scoliosis, terrible restrictive lung disease. This is not the kind of patient I want to be poking around in the axillary with a needle. She now has severe um are and she also has intermittent pressing copy from markedly long pauses, sinus pauses detected on a loop recorder. She was planned for a mitral and try custody valve repair. And we were consulted for the pauses and whether or not to consider an epic cardio pacemaker implant versus an endo cardio pacemaker implant, epic cardio can be challenging as I've been told many times. It's a re op case. It's not easy to get to the epic cardio surface in some patients. The long term longevity of epic arterial pacemakers is a concern, especially in someone who's so young In a 70 year old is less relevant and epic cardio leads are not MRI compatible. She's a young woman with many problems. She's got many mris in the past that she might need them in the future. Endo cardio is challenging because of her thoracic anatomy. I'll show you her chest x ray. If we drop her lung, we're in big problems. Um and obviously can can compare with her repair track husband valve. And she has to live with that valve for many years. So we decided to interop leaderless pacemaker implant. This is just the sheath. Basically. What we do is we just kind of folded up on itself. This is the leaderless pacemaker still within the sheath and so I just put together a little composite. So this is the camera views that they took. This is the RV septum um told this is the RV apex, this is the delivery catheter going into the right ventricle here we're pushing the catheter up against the myocardial tissue. Then you just click a button, it gets released and now it's still attached to the tether. And then essentially what we do is we do to tug tests. One is I just yank on the sheet from outside, then Percy or ahmed or um it when he was here would just take a little forceps and tug on the leaderless pacemaker and actually make sure that stuck in the myocardial. Eventually you just cut that tether and then you're left with the final deployment position of the lead. This pacemaker here. It looks like it's touching the cords, but obviously there's no blood in the ventricle. And this is just our setup. When we're doing a tug test for this particular patient, this is at follow up. I just intentionally over drove pace her just to demonstrate. So this is the paste, curious as you can see here because it's on the septum it's actually quite narrow. It's always better to have a narrow curious, especially in a younger patient. And you can see here this is her obviously her chest x ray. This is a loop recorder implant and this is the leaderless pacemaker and its position nicely in the septum you can see it's almost going at you and backwards. A couple of take home points about interop leaderless pacemaker implant, which I think will become uh more common over time leads pacemaker implantation can safely be performed at the time of cardiac surgery. The implant can be performed in less than two minutes. It should be considered for patients who are appropriate for single chamber pacing and those at high risk for complications related trans venus devices or those who are high risk for require permanent and prolonged pacing. After surgery. There have been times for at least one or two patients where the surgeons have not put in an epic cardio lead. I think that's very safe to do as long as that when you come off bypass and you check the numbers. If the thresholds and the sensing looks good, it's highly unlikely that anything will change. These devices tend to be very stable. Mhm. And this is the future of leaderless pacemaker. So right now there's only a current single generation pacing. They are working on dual chamber pacing. So there's gonna be a leaderless implanted probably in the right atrial appendage and then one in the right ventricle. And there's one company now that's actually working on by ventricular leaderless pacing where they're actually putting it in the right atrium, right ventricle. And they're figuring out how to put a small lead list device into the coronary sinus. And then finally this is actually already available in clinical trials. We now have a leaderless pacemaker plus subcutaneous defibrillator. So nothing is in the venus system. And the leaderless pacemaker communicates with the subcutaneous IcD and tells it when the patients in an arrhythmia or not. So it's two ways to discriminate ventricular type of cardio. That's it. Thank you.
