 I'd like to now welcome back Dr. Aiden Sharkey to present a talk on transseptal puncture. Dr. Sharkey actually is very familiar to us in Toronto as he did his chronic anesthesiology fellowship here before he started on staff at the Beth Israel Dickens Medical Center as a staff anesthesiologist. He has published in structural heart disease and has an interest in both interventions as well as in focus, Dr. Sharkey. Hello, everyone. My name is Dr. Aiden Sharkey. I'm an attending cardiac anesthesiologist at the Beth Israel Dickens Medical Center in Boston. And I would like to start off by thanking the organizing committee for the invitation to speak at this conference. I myself was a fellow at Toronto General Hospital in 2018. So it is both an honor and a privilege to be invited back to speak at this conference this year. So the topic for today's talk is TE guidance for transseptal puncture. And I have no conflicts or disclosures related to this topic. The outline of my talk today will be to discuss the importance and give a brief introduction on transseptal puncture. I will then discuss choosing the right location and TE guidance, both two-dimensional and three-dimensional guidance for performing a transseptal puncture. And then I will finish up by discussing some challenging situations followed on by a case example. So the transseptal puncture is not a new procedure. And in fact, this procedure has been around since the 1950s when it was initially developed as a way of measuring left-aid drug pressures. And for the last number of years, this procedure has been performed very successfully using fluoroscopic image guidance. However, what has changed in the last couple of years is the reasons for performing a transseptal puncture. No longer are we performing a transseptal puncture for monitoring left-sided pressures, but we are now performing a transseptal puncture for doing invasive, very precise trans-catheter procedures on the left side, such as trans-catheter mitral valve edge-to-edge repair, trans-catheter mitral valve replacements, left-aid repented occlusion, paravivalent leak closures, and so on. And so the indication for performing the transseptal puncture is what has really changed and reinvigorated our interest in this procedure. So what this has meant is that performing a transseptal puncture has gone from being an imprecise technique to a very precise technique that needs to be both precise and accurate, and not alone that, but a procedure that is specific to the procedure at hand and also specific to the patient in which this transseptal puncture is being performed on. And so why is it important to perform a very precise transseptal puncture? Well, there's two major reasons in my point of view for being precise and performing a transseptal puncture, and that is, first of all, patient safety, and second of all, to increase our chances of procedural success. So first of all, from a patient safety point of view, and to understand this, we need you to go back to the embryological origins of the interatrial septum. And from a very basic point of view, the normal interatrial septum is made up the septum primum and the septum secundum. And the septum primum initially forms, which separates the primitive common atria into left and right structures. And subsequently, the septum secundum is formed, and the important point to note here is that the septum secundum is formed by infolding of the atrial walls, and it's thus considered and is a extracardiac structure for space. And so the septum secundum doesn't completely fuse with the endocardial cushion, and the area where there is no fusion is known as the phosphorvalus. And this is the only true interatrial septum that separates the right and left atria without going through an extracardiac space. So performing a transseptal puncture in the extracardiac space is not an option as this exposes the patient to the risk of pericardial effusion. And so what we aim to do whenever we perform a transseptal puncture is we solely perform this through the phosphorvalus, and this is our only point where we can safely cross from the right side to the left side. And so looking at this from an echocardiac point of view, we can see here that the thin portion of the interatrial septum or the phosphorvalus is a very, very small structure. And so this is why we need to be very precise, very accurate for these procedures to minimize the risk of going through that extracardiac space and causing complications such as a pericardial effusion which may turn into a tamponade and an emergency situation for these patients. Now the second reason for being very precise and accurate in performing a transseptal puncture is to try and increase our procedural success. As I alluded to earlier, we are performing very complex interventions on the left side and we need to be very precise where we perform our transseptal puncture because where we perform our transseptal puncture will determine the maneuverability of our catheters within the left atrium. And so really, this is why each transseptal puncture needs to be not alone patient specific but it should also be procedure specific as where we perform our transseptal puncture will determine the maneuverability of our catheters within the left atrium. And so wash could be a very easy procedure, maybe a more difficult procedure if it is a transseptal puncture is not performed well. And a very easy procedure could be a very difficult procedure if it is performed in the suboptimal location. And for optimal results, such as this patient, this is why we need to be very precise and accurate where we perform our transseptal puncture. And when we perform a suboptimal puncture, we may end up with suboptimal results such as these patients who ended up having a paravital or leak and also a dislodged of the device. So now moving on to choosing the right location for performing the transseptal puncture. And as I alluded to before, this is both patient specific and also specific for the procedure that is being performed. However, there are some basic rules that we tend to follow when performing a transseptal puncture. And the basic rules are that we always perform the transseptal puncture within the phasor valus. That is the thin portion of the septum. And we always try to perform it at a very specific location. And what I mean by that is that between the echocardiographer and the interventionist, we should sit down before and decide where exactly in the phasor valus we're gonna perform this puncture. Is it gonna be more anterior? Is it gonna be posterior? Is it gonna be higher up? Is it gonna be lower down? And what's our septal height needed for the procedure? So this is what I mean by performing it in a specific location. Now there's some rules as to where we do not perform a transseptal puncture. And we do not perform a transseptal puncture in the thick portion of the intraectual septum. We do not do this procedure blindly. We do not do this procedure through a PFO. And we also tend not to do it through a very lipometous or a very thick septum. So these are some of the basic rules. And in terms of exact location on the phasor, there are some very good articles that have shown where the ideal location is. However, one thing I will say about following these locations is that we tend to be more patient-specific and procedure-specific. So in this example here to the right, they would say that for a mitreclip, we should be performing our transseptal puncture in a very superior and anterior location. However, for edge-to-edge repair in a more posterior-medial location, we may need to perform this in a much more inferior and much more posterior location that is depicted here. So we really need to be very patient-specific and procedure-specific for this procedure. Now moving on to TE guidance for the transseptal puncture. And it's important to know the rims of the phasor ovalis with regards to our imaging planes for guiding these transseptal punctures. And for this, we need to know the superior, the inferior and the anterior and inferior rim of the phasor ovalis. And then we also need to be able to guide the interventionist with regards to septal height above the mitrevalve annulus prior to crossing the intra-atial septum. And it's only when we really dissect down the heart and we can see that the phasor ovalis, which is located approximately here, is a very small structure. And not alone is it a small structure, but it's very close in proximity to a lot of other structures. You know, we can see its proximity to the IVC-SVC, tricuspid valve, the coronary sinus. So it's a very complex structure, much more complex than we give it due regard to. So in terms of image guidance for the transseptal puncture, as I alluded to before, we need to know the rims of the phasor ovalis. And the superior, inferior rim is depicted here in our midisophageal bicable view, where we can see the superior rim to the right and the inferior rim to the left. Looking at our anterior, posterior rims, this is usually obtained in our midisophageal short axis view. And again, here we can see our anterior rim and posterior rim of the phasor ovalis. And then as I alluded to before, when we talk about our transseptal height, this is obtained in our midisophageal four chamber view. And this is the height from the septal indentation to the plane of the mitral valve annulus. And so using a combination of all of these views and very quickly going between all these views, we should be able to guide the interventionalist with regards to performing a precise and accurate and safe transseptal puncture by transitioning between all these views. Now, if only obtaining these views was the crux of the procedure, it is not. However, what is most important is not alone obtaining these views, giving the information back to the interventionalist, but the difficult part comes in, tracking the transseptal needle as it is moving across the phasor ovalis and tracking the needle as it moves down from the SVC into the phasor ovalis and then guiding the transseptal needle and the interventionalist to that exact location. And that is where the art and the tricky part of this procedure comes into play. And so like all invasive and complex procedures, it is best to break these procedures down into building blocks. And we have recently published a protocol that we tend to follow for performing the transseptal puncture. And we've called it the PITLOG protocol. And what the PITLOG protocol does is that it is, tends to, we like to break down this complex procedure into small building blocks for teaching our residents and fellows performing this procedure. And it's a methodical approach to performing the transseptal puncture. And it involves practicing, obtaining the views, identifying the needle, tracking the needle as it comes down onto the phasor, locating the needle on the phasor, optimizing the location and then finally crossing the phasor ovalis into the left side. And so what we do is we break down the steps. And so first of all, as I said, this is the practice phase where we practice obtaining our bi-cable to look at the superior and inferior rims, our short axis view to look at our anterior posterior rim and our four chamber view to get the septal height. Because not every patient is at the optimal, you know, 90 degree, 45 degree omni-plane angles for these. And based on the rotation of the heart in the medial stymium will determine where the optimal omni-plane angle is for obtaining these views. So this is why it's important to practice obtaining these views for that specific patient. Next, we move on to the identification phase. And this is identifying the transeptal needle in the IVC, going up into the SVC. And this can be tricky, especially in patients that have, you know, other catheters or wires in the right atrium. And so this is why it's important to track the transeptal needle as seen here as it's coming from the IVC, going up to the SVC. And so this is the identification phase. Next is the tracking phase. And we can see here that we are continuously tracking the needle as it comes down from the SVC, falls onto the phassovalus and begins to tent the phassovalus. And the, you know, the key portion here is continuously tracking the needle as it's coming down onto the phasso to cause some degree of indentation. So we need to keep the needle in view the entire time. And we find that, you know, if you're losing the needle, you know, we find that the needle tip tends to cause a reverberation artifact and just locating this reverberation artifact, if you're having difficulty locating the needle tip can be a good method to make sure that you're looking at the tip as opposed to the shaft of the transceptile needle. And so next we wanna locate the position of the transceptile needle within the phassovalus. And we need to locate its position with regards to the rims of the phassovalus. That is the superior inferior rim as well as the anterior posterior rim. So where exactly is the point of maximal indentation or the needle tip within the phasso? We then will, you know, because we've already predetermined where we want to cross, we will optimize our position within the phassovalus. So we can see in this example here, we were a bit too anterior to where we wanted to be. And so our interventionist was able to use this information and move the transceptile needle to a more posterior location. So this is the optimization phase of our pitlog protocol. And again, we always look at all the views. So again, we'll go to our four chamber view and we will look at our, you know, septal height with regards to where this transceptile needle is to make sure that we have adequate height above the mitral valve annulus for our proposed procedure. And then finally, we will cross the intreatal septum under constant visual guidance under TE guidance. So we can see here the image to the left, you know, we are using radio frequency ablation to cross the septum. And then not alone that we are tracking the wire as across the intreatal septum into the left upper pulmonary vein as we can see in the image to the right. And so that is what we tend to do for our transceptile punctures. We tend to protocolize it. We find this good from a, you know, a teaching point of view and also it breaks down this complex procedure into manageable building blocks. And so that is our pitlog protocol that again, we have published recently in JCVA. So now let's talk about, we've talked mainly about two-dimensional imaging with regards to guiding the transceptile puncture. But what about 3D imaging? Well, we also talked about, you know, an element of 3D imaging with regards to, in our previous examples, we did use simultaneous orthogonal plane imaging. And this is a very good 3D imaging modality that is used, you know, quite routinely for performing these procedure. And orthogonal plane imaging allows us to view a structure in two different orthogonal planes. And so this is a very good imaging modality for performing this procedure. And so here we have an example of us utilizing orthogonal plane imaging where we have our, you know, on our reference plane on the left here, we have our short axis view. And then we will use orthogonal plane imaging to have our orthogonal image on the right, which gives us our, you know, superior, inferior rim of the phosphor ballast. So using this imaging modality, we're able to see, you know, the anterior posterior as well as the superior, inferior rims of the phosphor ballast in the single imaging window. And not alone that, but when we're guiding our catheters, we're also able to use simultaneous orthogonal plane imaging for viewing our transeptum needle within the phosphor within two imaging planes. And so this is a very good imaging modality for performing this procedure. Now I will say that it is very important to know where your reference plane is, because the machines will automatically obtain the orthogonal plane at 90 degrees to your reference plane. And so if, for example, on this image, you know, we have an image of the mitral valve where we have our reference plane in the long axis view, we used orthogonal plane imaging to get a commissural view. However, it's important to know that this image is actually flipped. So what should be medial is actually lateral and what should be lateral is actually medial. So it's very important to know and not fall into what we call the orthogonal plane trap when performing this procedure using orthogonal plane imaging. Now what about using volumetric imaging for performing transeptum puncture? And really in our experience, we have not found that using volumetric imaging alone is useful for performing this procedure. While we're able to visualize the rims, we don't find it very good for image guidance. And this is because if we were to get the same image that the interventionists get when performing the procedure under fluoroscopic guidance, we would need to have extensive manipulation of our volumetric image. Not alone would the image need to be flipped left to right, but it would also need to be turned upside down in order to get this representative image that the proceduralists get using fluoroscopic imaging. So we do not find that using volumetric imaging alone is of significant value when performing this procedure. However, what I will say is that we have found using multi-plane and reformatting a very useful imaging modality. And so in this example, we're able using multi-planar reconstruction, we're able to visualize all rims of the Phaserovalis, we're able to add 3D markers. So we have a volumetric image as well up to the left. And so we are now beginning to perform more of our transeptum punctures using live multi-planar reformatting in order to guide this procedure as highlighted in this case example here where we used live MPR to cross the intratual septum. And so this is just a still image where we can see where we're able to precisely locate exactly where and get visual feedback through multiple planes as to where exactly we were within the Phaserovalis. Now let's talk about some challenging situations. And the first challenging situation arises in that differing nomenclature between what the interventionalist is used to and what we as echocardiographers are used to. And so we have recently published a article also on the differing nomenclature between different imaging modalities of the intratual septum. And I would advise people to read this to get a more in-depth understanding of this. But to briefly describe what I mean is that when the interventionalists are viewing on their fluoroscopy, they're looking at the heart in the attitudinally correct position that the heart takes within the mediastinum. And they're also viewing the heart in relation to where the image beam intensifier is. And so what they are seeing is the more anatomically correcter, attitudinally correct anatomy. Whereas when we look at it on echocardiography, we are looking at a more Valentino description of the heart. That is, the heart is broken down into left and right sides. And so that is where our descriptive anatomy comes from. But this is not correct in terms of anatomically correct because if it was anatomically correct, the right atrium, the right ventricle actually sits more anterior, the left ventricle more inferior. However, in the Valentino description, we have the right ventricle on the right, the left ventricle on the left. And so differing nomenclature, it's important to understand between TEE guidance and fluoroscopic guidance. Another challenging situation could be in patients with very large atria. And it may be difficult to obtain adequate tending and it may require some interventionists to put excess curvature on their tracental needle. So this is information that they need prior to performing their procedure. Another challenging situation is patients who have a very lipomodous septum. And again, this is information you should be given to your interventionist as they may need to use radiofrequency ablation if they are to perform a tracental puncture in patients with a thicker or more lipomodous septum. And finally, patients with aneurysm septums may be at risk for sharing of the phosphovales from the septum or also causing excessive tending and what they do puncture through the phosphovales, potentially injuring structures within the left atrium if there's excessive tending. So now I'm gonna conclude with a quick case example of a performing a tracental puncture. And this is a patient who was undergoing a mitral valve edge-to-edge repair and they had a P3 leaflet flail causing severe mitral regurgitation. And so looking at where we are planning where we were to perform this procedure and if we were to perform this procedure where the guidelines state in a very superior and anterior position, we wouldn't have very good maneuverability to get at this more posterior medial location for the flare leaflet. So what we had decided was we needed to perform a very inferior and a very anterior tracental puncture. So we needed to perform a tracental puncture in and around this area. And so this is what we set out to do. You know, we went through the practice phase of obtaining the ideal images. We identify the needle coming from the IVC into the SVC. We tracked the needle. We can see the needle tip here. We tracked it, you know, falling from the thick portion onto the thin portion of the fascival valus. We located the location of the tracental needle within the fascival valus, the location of maximal tenting. We then optimized our location with regards to all the rims, the superior, inferior, anterior posterior rim, but also the septal, the tracental puncture height above the plane of the mitral annulus. And so with this, we were able to perform very optimal tracental puncture for performing this edge-to-edge repair in a very posterior medial location of the mitral valve. And then we crossed on the visual guidance. You know, this was a very commissural edge-to-edge repair and this patient had a very good result. And this was in part to us spending a bit of time optimizing the location for the tracental puncture. So in conclusion, I will say that, you know, the fascival valus is a very, you know, simple yet very complex structure in terms of its relationship. It is very important to be very precise, very accurate in terms of where you perform a tracental puncture. You know, we traditionally use our four-chamber short-axis and bi-cable views for identifying all the rims of the fascival valus. We tend to use a very protocolized approach that is patient-specific, procedure-specific and for crossing the septal or for crossing the septum in a very precise location. And we tend to be, you know, moving towards using live multi-planar reconstruction for performing this procedure to optimize our results even more. I thank you for your attention and I look forward to a panel discussion and I'm open to answer any questions that may arise. Thank you.