My name is Dave Callens and I'm a professor of medicine at the Perlman School of Medicine at the University of Pennsylvania. I'm speaking today about transeptal catheterization techniques. These are my disclosures. Transseptal catheterization was initially conceptualized to measure left atrial pressure in patients with valvular heart disease. It supplanted transbronchial or suprasternal puncture to the left heart and eventually was supplanted itself by Swann Gans catheter recordings. Its present uses are myriad. We use it on a daily basis for atrial fibrillation, ablation for ablation of left-sided bypass tracts, left atrial tachycardias, ventricular tachycardia, and it's particularly helpful in that application for reaching the septum more directly than a retrograde aortic approach will allow. Left atrial appendage closer procedures and structural heart applications. What could possibly go wrong? It's kind of amazing when you look back, the complications in the initial series range from two to 6%, including such horrible things as left atrial perforation, cardiac tamponade, stroke, air embolism, aortic perforation, and even death. Presently, there's a very low instance of complications. Certainly major complications should be much less than 1% in experienced centers. In order to get to that point where complications are low, there's an importance of mastery of this procedure, of understanding the underlying anatomy, of mentoring, and practice. This is a transilluminated depiction on the Visible Heart Program from the University of Minnesota, looking with the light shining through to the right atrium across the fossil vallis. It's a very thin membrane, larger than I think I initially conceptualized, and it's bounded on the top by the limbus of the fossil vallis, and we'll talk more about that in a second. Doesn't look like such a barricade to entrance to the left atrium. However, most important part of this, looking at this in kind of in situ, in a normal heart, here viewed in the REO projection, is not the fossil vallis itself, but all the other things that surround it that we need to avoid. Most importantly, and if you take one thing away from this lecture, this is the most important point, the aorta is immediately superior and anterior to the fossil vallis. So if you look at this from the standpoint of moving the catheter and the sheath apparatus from the IVC up to the SVC, first of all, notice that that's not a straight vertical line, but kind of a right angle almost, where that SVC and the IVC kind of take a diversion away from the vertical. If you can imagine following this blue line, which describes the vertical plane of the transeptal apparatus needed for safe movement of the needle. It's bounded by the anterior third of the SVT, SVC, and the middle third of the IVC. This will land you right in the fossil vallis, just as you come under the limbus, the superior part of the fossil vallis. If you're more anterior to this line, you will encounter the aorta, the conduction system, the coronary sinus as you come down. If you're more posterior to this line, you risk the damage to the left atrium and particularly perforation because it's much smaller, the more posterior that you go. We'll see pictures of this in slides to follow. So transeptal can be done totally on the basis of fluoroscopic anatomy. And in the old days, this was helped by either putting a pigtail in the aorta and or catheters in familiar spots, the coronary sinus and the His bundle projection that would help find the fossil vallis fluoroscopically. In this way of thinking of things, the fossil vallis is situated between the His and the CS catheters in both the areo and the leo fluoroscopic views. Furthermore, the His catheter marks the location of the aorta, specifically the caudal portion of the aorta or the intersection of the right and the non-coronary cusps. So that is where you would expect to find the recording of the His bundle electrogram. Fossil vallis is actually pretty large as we mentioned before, almost by average two centimeters in vertical diameter, one centimeter in horizontal diameter. And the thickness is only two millimeters and it can be even less if the septum is aneurysmal. Let's talk about some of the basic equipment that you'll need to understand. And I think the most important part of this is there are a lot of different sorts of ways of solving this and they will vary from lab to lab. You need to be familiar with what's available to you. So there are many different sorts of sheets that can be used for transeptal needles, again of different varieties. Most labs use pressure transducers. This is not mandatory. Red wires, fluoroscopy is of course necessary and biplane fluoroscopy is helpful, but not mandatory. And I think whenever you do a transeptal, you should be prepared for something to go wrong. So in our lab, we have a pericardial tray available and in a spot that everyone knows where it is. And we also have blood matched in case that's necessary. There are a lot of different sheets, as I said before, for transeptal. There's an array of the short sheets, which were originally thought up to allow positioning for left-sided and right-sided bypass tract ablation. And on the right side of this, the agility sheet, which we use a lot for transeptal applications. Most important part from this slide though, is this part from the different shapes. There are also different lengths of the sheets and it's very important to understand the relationship of the sheath length and the transeptal needle length, because you want to position the transeptal needle just at the edge of the sheath as you pull it down. So if we wanted to outline this into steps of the transeptal procedure, before we even start, patients certainly with atrial fibrillation procedures are double anticoagulated. We continue the oral anticoagulation and give heparin before the transeptal, aiming for an ACT of 350 seconds. Step one, if you wish, is reference catheters to help the fluoroscopic guidance of the procedures. I don't usually do this, although it is helpful to have a coronary sinus catheter, and we need that anyway for most of the procedures that we're doing this way. So I have that in before I start. Step two is positioning of the transeptal apparatus in the SVC. Step three is pull down from the SVC. Step four is confirming placement in the fossil valleys, then septal puncture, validation of the needle, and it's actually located in the left atrium in a safe spot, and then advancing the dilator and the sheath apparatus to the left atrium, and we'll go over this in further diagrams. So I'm going to show this as an REO pull down. This isn't as meaningful in that it doesn't show the double jump that we'll talk about, but it does show that in the left anterior oblique projection, which I'll show in a second. So the transeptal apparatus is advanced over a 3-2 wire to the level of the bronchial bifurcation. I'll play this video in a second. It's not quite as high as I would like. This should be the bifurcation of the bronchus. You can see it on the fluoroscopy. It's important not to advance the transeptal apparatus without wire support. It'd be very easy to perforate the right atrium if this were done. Once you're up at the top, you withdraw the wire and aspirate to clear the vacuum that's made by withdrawing the wire. You advance the needle to the very tip of the dilator, and the proximal tip, the tip in your hand, has a bevel that you can position if you look down the barrel at four o'clock. That's usually the right degree of posterior that you want to aim the needle. You lock the relationship of the needle and the sheath with the right hand and pull down until you see the double jump. This is kind of what this looks like, although the double jump is not so apparent. This is the entrance over the aorta into the right atrium, and the second jump is over the limbus of the fasciae valis. It's a lot easier to see in the next recording in the LAO, and it's important to admit here that I'm cheating. The other catheter that you see in this projection is the intracardiac echo catheter, and we'll see the importance of ice in this in future slides. This is the LAO pulldown, and it shows that double jump a little bit better. The first is the entrance to the atrium, the second is just when we jump over the limbus of the fasciae valis, right there, and then it settles into the superior part of the fasciae valis. That's a good position for translateral puncture. Again, this is a little cockeyed view. It should be rotated about 90 degrees counterclockwise, but you can see as you come down from the SVC, the fasciae valis is guarded by that superior aspect of it that's called the limbus. The most important part of this is if you're in the right spot, if you've seen that second jump, then you can advance the entire transeptal mechanism forward, and it should catch on the superior limbus of the fasciae valis. If it's not in the right place, we'll just continue to ride back up into the right atrium, and that will not give you enough purchase to be able to do the puncture. You can adjust the needle, typically it's needed to be more posterior, more posterior is towards six o'clock for the rotation of the bevel. If it is correctly seated, the apparatus will hold firmly against this limbus, and you know that you're in a good position. At that point, you can deploy the needle approximately half a centimeter outside of the sheath. Very often you'll see, you'll feel a pop, and sometimes you will see the dilator advance as it jumped a little bit after the needle made the puncture. Not quite done yet. You're in the left atrium and you would measure left atrial pressure at this point, but you have to be careful about the course of the needle and the dilator once the septum is crossed, particularly in patients with normal atrial anatomy and small left atria, unlike the AFib procedure. Built up pressure, built up mechanical pressure once relieved can lead to lurching of the system, which can damage the posterior left atrium or the left atrial appendage. This is especially likely negotiating the step up, the increase in diameter between the dilator and the sheath. So we're seeing this here. The dilator is across, the sheath is still on the right atrial side. We're trying to advance the sheath and we're kind of, in this example, which I don't exactly like, telescoping the dilator and the sheath. Sometimes this is better done with just keeping pressure on it. The most important part of it is though, the entire leverage that you have is the transeptal needle. So if you pull the needle back into the right atrial side, it's impossible to advance and everything will just kind of fall over on itself and come back to the right atrium. I think it's important to note that even with that uncomfortable part of the lurching that happens with the transeptal apparatus after you relieve the pressure from the septum, the left atrium is very large and you have an extra place to kind of land, an extra distance to land in with the superior left pulmonary vein. And we'll see how important it is to aim at this in future slides. It's important to note that anytime anything is withdrawn from the sheath, here, mostly talking about the needle and the dilator, but later for catheter exchange, there will be air entrained in the sheath, which needs to be aspirated and flushed to prevent air embolism. Once the needle and the dilator is withdrawn, you can advance the catheter through the sheath to the left atrium. It's important not to fall out with this sheath because then you'll lose the access for the catheter. It's important to maintain systemic anticoagulation with heparin. We monitor ACT every 30 minutes and aim for a target of greater than 350 seconds. So there are additional techniques, I've hinted at that already, in addition to anatomic understanding and fluoroscopic anatomy. Pressure measurement is used in many labs. I'll show a picture of dye staining of the septum. I don't do that. I've never done it, but it's an old-fashioned way to do it. I'm a big fan of echocardiographic guidance, typically with intercardiac echo. And at the end of this lecture, I'll have some thoughts about managing more difficult transeptal procedures. Pressure monitoring can be added to the transeptal procedure for increased recognition of when you've actually done the transeptal puncture. As you can see from left to right during continuous pressure recording, it starts with right atrial pressure. Then the system is damped because the needle is up against the septum and can't transduce the pressure in the middle of the tracing. Once the puncture is completed, the pressure waveform changes and increases with left atrial pressure. So this can be helpful in confirming that you're actually across in the right spot and not in the aorta. This I've never done, as I said before, but it's possible to do dye visualization of the septum. In this LAO view, you can see that the dye is kind of held by, again, the limbus of the fossovalis, ensuring that we're in the right spot. I'm a big fan of echocardiographic visualization for transeptal puncture. It allows direct visualization of the atrial septum, as well as the surrounding anatomic structures. It's particularly helpful in anatomic variations, things like atrial septal aneurysms or rotated anatomies. And I'll show some examples of this in future slides. Most importantly, it allows the visualization of the left atrial target zone, which again, I'll define in a little bit. It's very helpful for fluoroscopy-free procedures, and at very least, it allows prompt diagnosis and allows for immediate intervention for complications, sheath thrombus, which we never knew about until we started using ice imaging, and particularly pericardial effusion. So from left to right, we're moving the catheter, the ice catheter, from a relatively anterior to a relatively posterior spot during the transeptal procedure. So on the left, you can see the T of the transeptal apparatus, unfortunately aimed at the ascending aorta. So that's two anterior. In the middle, we can see the transeptal apparatus, and it's tenting the fossovalis, looking towards the left atrium, but the landing zone, so what would happen if we pushed the transeptal apparatus forward, its trajectory would be aiming right towards the left atrial appendage. So if you had that lurching that we were talking about before, it's possible that you would damage the left atrial appendage. Moving the transeptal apparatus and the echo a little bit more posterior, you have the right view, which is just perfect. You can see a large expanse of the left atrium, but your trajectory is towards the left superior pulmonary vein. So if you happen to break the plane of the left atrium, you would safely fall within that space. So it's the safest way to arrange your transeptal. You can also think about this because the fossil valence is rather large, you can optimize the position of transeptal passage depending on what you want to deliver to the left atrium. So for example, doing a balloon-based PVI, we often aim a little bit anterior and low within the fossil valence to encourage the ability to kind of move the balloon back on itself to get to the right inferior pulmonary vein and et cetera. So this is what this looks like with ice guidance. We've positioned the transeptal apparatus and we're tenting at the fossil valence. This is a little bit low. We can see in the background that we're aiming at the left and right superior, or the left inferior and superior pulmonary veins. We apply some more pressure to the transeptal apparatus. We cross into the left atrium. That was very atraumatic and you have lots of room for the transeptal apparatus to fall to the left atrium. So that's very calm, very reassuring. This is not so calm and reassuring. So when we first started using ice, we noticed these sheath-associated thrombi rather frequently. And that really led us to changing our strategy into doing double anticoagulation before we even had the sheaths in the body. I certainly wouldn't want to drag that sheath over into the left atrium where it could go somewhere we didn't want it to go. We can also see often after ablation, and we think this is either thrombus or related to endothelial disruption, but the arrow pointing in the right image on something flapping just below the right superior pulmonary vein, which is not a good look either. This is even more important to recognize. So small effusions very frequently collect at the dependent portion of the heart. So the posterior or even the inferior part of the posterior part of the heart. So it's important if you're using ice to look at those areas of the heart so you can detect very small effusions. These typically resolve, the bleeding resolves with getting rid of the heparin anticoagulation. And they're better detected early than late. So I wanted to spend some time talking about difficult transeptal procedures. And this is a list of things that can make transeptal procedures difficult. We'll spend a lot of time on thick or fibrous septum. And that often happens with repeated transeptals after recurrent, particularly atrial fibrillation and repeated procedures. Atrial septal aneurysms can be difficult. It's difficult to do transeptal procedures with extremely dilated right atria just because the apparatus doesn't necessarily reach far enough over to the fossil ballast. In the setting of prior septal closure devices, transeptal can be complicated. In very tall individuals, the sheets might not reach the vertical distance well enough. Patients with small, normal left atrium and pacing leads in the right atrium can get in the way of movement of the transeptal apparatus down to the fossil ballast. This is a very frequent abnormality in particularly patients with atrial fibrillation, lipominous hypertrophy of the septum. This is not a particularly dramatic example. You can see there's kind of like a dumbbell in the very thin part is the fossil ballast. So it's relatively easy still to find this spot. One of the things that makes transeptal puncture with ice guidance in patients with lipominous hypertrophy difficult is that the lipominous hypertrophy really affects the transmission of the ultrasound beam. So it's really blocked and you really see kind of the far field left atrial structures are very easy here because you don't have the same delineation going through the septum. So that can be a little bit more difficult. This is a really spectacular example of an atrial septal aneurysm. So we're looking at the right atrium on the left view and you can see that jump rope kind of coming over when there's a breath and it's really taking up the entirety of the right atrium. The opposite happens in the right view. So we have the transeptal apparatus, we've positioned it right in the middle of the aneurysm which is a mistake. We'll get back to that in a second. And we're stretching the septum all the way over until the very expanse, the very lateral expanse of the left atrium. So if you suddenly punctured, it would very likely lurch and go somewhere that you didn't want it to go. So there are a couple of tricks about this but the most easy is rather than going in the very middle of the septum to go either to the vertical or horizontal barrier of it, border of it so that it can't stretch as very far. There are also some differences in kind of the kit that we would use to do this if we really were encountered by this too. It really takes away some of the drama. So this is an older thing called the safe sept needle. It's really been supplanted by other products but this was a really cool idea rather than the usual BRK needle, which is a needle. This was safe sept needle was only a needle when it was positioned within the apparatus of the dilator. And as soon as it goes through the septum, it curves on itself and really becomes more like a wire so that if you really stretched all the way over you wouldn't have to worry about that lurching. This is an example of a case that I did. This is a patient who had a prior left atrial surgery to remove a myxoma. And you can see that the fossil ballast is very thickened and fibrose appearing. It's a very echo dense sort of look to it. So we approached this with the radiofrequency needle which is a little bit of a help. I'll show you a picture of what this looks like. It's kind of nice to see this, excuse me. So you can see when the evaporation of the desiccation is done with heat energy from radiofrequency, there's a shower of bubbles. Thankfully those don't cause any damage but you can tell very clearly when the needle is in the left atrium. So the radiofrequency results in electroporation of the septum and very little in the way of physical force is needed to get the needle over. So you can really do septal crossing with very minimal forward advancement. That's just the beginning of this. So that's just getting the needle across. It has been shown in a retrospective comparison of standard versus RF needle to be a little bit safer. So these investigators used ice guidance and did 1500 and 1550 procedures. Some without, some with radiofrequency needles. When they use the radiofrequency needle they've noticed less frequent transeptal failure, a decreased incidence of tamponade and a shorter time required for the procedure. So we have the needle across. That's usually not actually the real problem. The real problem is that step up again between the dilator and the sheath. So the answer to this, it seems like it should be pressing harder but most often in EP that's not the answer to anything, not a good answer to anything. So if you're pushing as hard as you can and it won't go across, you need to do something else. And again, the weird thing about this is we're pushing up to go posterior and left. So there's kind of a diminution of the direction of pushing to the direction of the vector that we wanna develop. So there really is a disconnect here. So next steps are often putting a stiff wire through the dilator, which is in the left atrium to allow at least safety and kind of channeling of that force that you're using to push up. So you can see the wire in the left view, left upper view. And the important part is where is the wire? So we want the wire in the left atrial in the left superior pulmonary vein and not in the left atrial appendage. So you can see that it looks like that's happening in the right superior view, but there's a very helpful additional view with ice imaging that's shown in the lower views. So this view is taking the ice transducer, moving it through the tricuspid annulus and up to the right ventricular alpha tract. And in this view, you can see that the wire in the left is going into the anterior structure, which is the left atrial appendage. So we don't wanna push this into the left atrial appendage and risk perforation. In the right lower view, the wire is successfully going into the left superior pulmonary vein, which is posterior to the appendage. And this is very safe if we push here. So knowing that this wire is exactly where we want it to be, we can push as hard as we want to. And here you see the catheter going over into the left atrium. Another trick to this, it's a little bit harder to do, but if you can get the wire to go into the right superior pulmonary vein, then that idea of the direction you're pushing and the direction that the catheter is actually going to go to, kind of straight up pushing, straight up almost to the right superior pulmonary vein vector, that hearing the pushing and the vector really makes this a lot easier to do too. Another kind of trick that's often helpful with this is there's a number of different pigtail wires. This is the Protrac wire. It's largely been supplanted by a new product called Versacross, which is just a smaller pigtail that could actually fit in the left superior pulmonary vein. But if you're using this to push against, it's very atraumatic. This picture on the right-hand view is an LAO picture of a transeptal puncture from a superior approach, which again is a very advanced sort of thing, but very much helped by having something that you can push against to the left atrium. Many patients with a prior ASD or PFO closure devices will end up developing atrial fibrillation and then require a transeptal access to the left atrium for this procedure. Most of the time, we're lucky with this in that since the most frequent location for ASDs is a secundum location, usually there is some free fossil valence that's available underneath the closure device. Here's an example of this in the following slide. So you can see in this RAO view on the left that we're going a little bit underneath the closure device and it's just a normal transeptal puncture. We can deliver the sheath just under it into the left atrium. This is what that looks like by echo. So we're positioning the transeptal apparatus below the ASD closure device and then puncturing just like normal. Again, this helps with ice. Pre-procedural imaging can also help as well just to make sure that there's enough room underneath it to safely cross. This is an experience that a partner of mine, Pascualia Sant'Angeli, put together of 39 atrial fibrillation patients who had prior ASD closure and how they managed that. So transeptal access in a portion of the native septum, usually underneath the ASD, was possible in 90% of these patients. However, in four patients, they actually did a transeptal through the closure device. This direct access was very difficult. It took a wire passage and then serial upsized dilators until the sheath could be passed. And it took a lot of time, more than an hour for double transeptal access in the group that required passage through the closure devices. I've never done this. I hope I don't ever have to, but it's nice to know that it's possible. There were no complications in this experience. This is an example that I did going through a surgical ASD patch. So again, we have the dilator and a Kirby wire into the left atrium, but we're unable to pass the sheath. The sheath will not, the step up of the sheath will not go across the septum. So one trick to this is atrial septoplasty. So here you see the same RAO and LAO reports and we've transitioned to moving a balloon over the wire. And you can see the guide marks of the balloon positioned over the atrial septum. It's actually very easy to see with intracardiac echo as well. And the balloon is inflated. And then it's very easy to pass the sheath through the hole that the balloon's made in the septum. This is unusual to have to do, but it's a good skill to have to have and it's not very difficult. They kind of bail you out of what would otherwise be a failed procedure. Jeff Arklis, another partner of mine, performed a series of transeptal access with previously scarred or repaired interatrial septum. Of 3,500 AF ablation patients with multiple prior transeptal procedures defined as a history of greater than or equal to two prior AF ablations with double transeptal. 251 of them either had this situation or a prior atrial septal repair over a period of observation of 2001 to 2012. Transseptal was routinely accomplished in the majority of patients. 222 patients are 99% in the multiple transeptal procedures that happened prior and in 97% of patients with atrial septal repair. So this is spectacular good news. All of these things we just talked about aren't necessary except in the minority of even the worst sort of populations of patients who you're performing transeptals on. There were no complications in the atrial septal repair group and there was a low incidence, 1%, in the multiple transeptal prior procedure group. So this is pretty simple even in the worst sorts of populations. So to summarize transeptal catheterization. Transseptal catheterization is an essential technique for left atrial interventional electrophysiology procedures and it's really important that you understand and become familiar with it. It is safe and effective if proper precautions and training are performed and if you have a very detailed understanding of the anatomy. Intracardiac echo adds precision in terms of understanding the left atrial target zone and safety as well as prompt recognition of procedural complications. There are advanced techniques for difficult procedures and situations but thankfully these are unusual. Thank you for your attention.

transeptal catheterization

complications

anatomy

pressure monitoring

echocardiographic guidance

atrial septum

tips and tricks