So, I'm going to just cover the background of how to implant a permanent transmittance pacemaker, and really what are the challenges, what we need to think about before going to this, because this is not without consideration of what could happen when you do this. So, what are the indications for pasting in a single ventricle population? And it's often sinus node dysfunction, which is in 9 to 23 percent of the patients, depending on the study you look at it. And then you have AV node disease that has been 2 to 16 percent. And obviously, depending on the type of disease you have will determine what type of pacemaker system you need to put in, whether it's just in the atria, or in the atrium, the ventricle, or just the ventricle. And then it comes down to where you're going to put the leads. You know, the gold standard is epicardial leads, because that's been a tried and true method of doing this. But obviously, we've got patients who've had complications to the epicardial approach for any number of different reasons. I'm sure they'll be discussed. And so, this has led people to become more creative in novel approaches to get an inside the heart, mainly the ventricle. So, if you go back and look at the studies that are out there, there's a couple that I thought were of importance as you consider what to do. This was an epicardial versus endocardial permanent pacing system in adults with congenital heart disease. And it included single ventricle and dual and biparticular patients. They had 106 patients. A lot of procedures, obviously, because these patients often undergo multiple procedures. The average age was older in their fourth decade. Heart block was the most common in this group of people. Once again, this is not necessarily Fontan patients. And sinus nodus function was in 20%. And what they looked at, and I thought was important in this study, was the procedural complications and the pacing system complications. So, on the left-hand side here, you'll see the procedural complications. And in the dark bars will be the endocardial systems, the transvenous systems, and on those, the epicardial systems. And some of these seem to be fairly obvious, like the difficulty pacing the system, or I'm sorry, the failed placement. Epicardial was more common because they couldn't get good lead position. Transvenous was less common. And once again, this is not the Fontan population. So, the thing about this, you can't look at this and say, okay, it's easy to put a lead in a Fontan because that's what we're discussing today. So, this is not probably as pertinent. Hematomas were more common in the endocardial versus the epicardial. Pericardial effusion were more common in the endocardial versus the pericardial. They often leave drains after surgery. Infections were more common endocardially. And the deaths were more common in the epicardial group. Procedural complication. If you look at the pacing system, transvenous systems last longer than epicardial systems. This has been known mainly because of scar tissue on the heart and the trauma to the lead. But that's both true for the ventricle and for the atrium. There's really no difference in generator complications, extracardiac stimulation, as far as like getting the phrenic nerve. Lead dislodgements are much more common in the transvenous, obviously, because the surgeons, if they do a good job, the lead is sold to the heart. And if you look at the longevity of the devices and failures, the epicardial systems, the proprietary failure in the endocardial system is much better. So, it's much less likely to have an endocardial system fail than the epicardial. And this is primarily due to the lead, not the, obviously, the generator. So, epicardial systems seem to be less durable with a higher instance of lead complications. So, let's look at thrombus, because this is one of the key things we have to think about in the fontan population. When you only have a single ventricle or a single atrium and you're going to put a lead in that, where's that clock going to go? It's going to be detrimental. So, this is a multi-center study of 202 patients with endocardiac shunts. So, these all had endocardiac shunts. So, this could be a fenestration of venous collateral. There are 64 transvenous, 52 epicardial, and 82 had no pacemakers. So, they are comparing pacemaker patients and non-pacemakers, and then endocardial versus epicardial. And this top graph over here is looking at the transvenous leads here, and then you have your epicardials, and then you have the epicardials here, and then you have the no pacemaker. And not surprisingly, the epicardial and the no pacemakers had very similar complication rates from thrombus, whereas the transvenous system with the leads inside the heart had a much higher incidence of thrombus. And this is a key thing we need to think about as we put these leads inside the heart. So, the transvenous leads incur a greater than twofold increased risk of systemic thromboemboline in patients with endocardiac shunts. And then you look at here, no transvenous lead versus a transvenous lead, event survival. So, you're much more likely to have an event here. It's basically the same as this if you have a lead inside the heart. And then having aspirin and morphine prescribed was not protective in this smaller study. So, if you look at equivalent study in the adult population, they actually…there's a certain patient population that it's very difficult to do biventricular pacing. And so, what they do is they go…they put a lead, a ventricular lead across the septum into the left ventricle. So, this is a transvenous lead going across the septum into the left ventricle. And this is called the alternative site cardiac resynchronization. And the nice thing about this is you can put that lead wherever you want it to optimize your resynchronization. They had 138 patients over a year follow-up. Thrombobolic events were seen at 2.6 per patient in 100 years, 14 events in 9 patients. And it's important to point out that all these patients had a low INR of less than 2.5. No one developed mitorial regurgitation. So, their take-home message was you can do this, but keep your INR between 2.5 and 3.5. And I think that'll be important for anyone who considers doing this because you need to keep them well anticoagulated. So, this is just my summary slide. This is the concerns we might have. This is the epicardial traces of transvenous. I think access, epicardial, has got to open the chest up. This, I think, is what we're going to discuss today. How do you get the leads inside the heart? Dislodgement, almost unheard of in epicardial, more common in transvenous. Infection, equivocal here, a little more common in transvenous. And, of course, that's endocarditis. AV valve regurgitation shouldn't really happen in epicardial. It can happen in transvenous. Longevity, the transvenous systems last longer than the epicardial. And finally, thrombus, it's much more common in the transvenous population. So, with that as a backdrop, I will turn it over to my colleagues. This is, of course, the University of Iowa Children's Hospital. And this is during the first and second quarter between the football game, we waved to the Children's Hospital. It's a little shameless plug. So, with that, I will pass it on to our next speaker.

transvenous pacemaker

implantation challenges

single ventricle population

epicardial pacemaker

endocardial pacemaker