Greetings, this is John Miller from Core Concepts in Electrophysiology in the Heart Rhythm Society. I want to take a few minutes to talk about electroanatomic mapping, how to use it, how to not use it. Now, I'm going to be giving almost all of my examples from using the BioSense Carto system. This is by no means an endorsement. It's the one that I've used the most and have the most experience with, but the general principles are applicable to all existing mapping systems. Here are my disclosures. So what can electroanatomic mapping do for you? Well, it can serve several purposes. It can serve as a ready anatomic reference, knowing where you are in the heart, where you've been. It can help with activation mapping, obviously tracing the course of activation wave front within the chambers and seeing where it's been coming from, working backwards. Voltage mapping, seeing where a scar is and where a scar isn't, where healthy tissue that you might not want to ablate is. And as for an anatomic reference, it can help in understanding anatomic relationships. I didn't think that the tumor was that large, but I guess it is. I didn't think the hiss should be where it is, but that's where it is. With catheter manipulation in a safe manner, you know that you can get from one point to another or you cannot get from one point to another because there's a septum in the way. You can plan ablation locations or strategize lines for ablation at different target sites, knowing what the shortest anatomic and or electrical distances between two barriers if you want to make a line of block and incorporate as much scar tissue, already pre-existing scar tissue into that so you don't have to do quite as much work. You can tag sites for subsequent viewing, getting back to a site that you thought, well, that was interesting during the arrhythmia. I'll come back to that so you can come back to it a little bit later and say, I want to paste from there or I want to look at it more closely. You can look at, with all the current systems, you can look at the monitor the location of other electrodes or catheters. It's extremely important in situations where, for instance, you're using a coronary sinus catheter as your reference electrogram. If that moves during the procedure and you didn't know that it moved because you weren't monitoring the location of that catheter, either fluoroscopically or with electron atomic mapping, you're going to get some really messed up activation sequences because your reference has changed. We'll talk about that a little bit more as well. You can tag locations of things you want to avoid, pacing leads where they might be, where they might connect to the chambers, valve orifices, especially mechanical valves, his bundles, things like that, and avoid damage to areas that you don't really want to damage, getting into a metacardic main branch, that sort of thing, or the his bundle itself. There's several purposes that electron atomic mapping can do for you. You can then design paths for linear ablation, again, trying to incorporate as much preexisting damage into an area as possible so you don't think about too much fluid with very prolonged ablation in normal tissue. You can improve map accuracy by gating the electrogram acquisition time to the respiratory cycle for those who use jet ventilation or a relatively high-frequency peptide line. This is not quite as important, but the free-living individual who's just breathing by themselves, you really need to make sure that you understand when the electrogram is acquired. It has to be when the heart is in the same position as the chest, the diaphragm going up and down, and so on. You can derive an indicator of catheter tissue contact. We need to have contact if we're collecting electrograms in most cases. We certainly need to have contact in most cases if we're doing ablation. Most systems nowadays give some kind of an indicator of contact force or just a degree of contact. It can give you an indication of the likelihood of making an effective ablation by that contact force and by some other indices, the ablation index, the force-time interval, integral, so on and so forth, that can help you out and say, yeah, we probably ablated enough there other than just looking at the electrogram You can compare maps pre and post ablation. Did I actually make a difference in the activation from point A to point B? You can even sometimes look at a prior procedure if you've done the same patient before or it's been done in your laboratory and see, okay, ablation was done here. I don't see much effective ablation at that site, so maybe we can touch things up a little bit. You can display propagation maps of the course of a wavefront. There are various iterations of this sort of thing where the actual wavefront is passing by you in different colors, just like an eraser bar on your screen of electrograms going past, look like that. A variety of ways of displaying this and fine-tuning it to get exactly the information you want. Providing voltage data regarding the location and extent of scar and, importantly, any residual conduction channels that exist between them. High-density mapping, as we'll see, has been a real boon to refining some of these conduction channels that are present or absent. And designating whether a linear block is present or whether there are gaps in a line and figuring out where those are is important than figuring out when you have closed them off with additional ablation and not done too much additional ablation, just kind of bombarding the area. Finally, decreasing fluoroscopic exposure to a patient, yourselves, and your staff is very important. And I would say most of our procedures nowadays in many labs are done without any fluoroscopy. Sometimes we use a few seconds here and there if there's any lack of clarity as to what's going on. This is an example of that. This is a young woman who had had several ICU stays and ventilator runs because of severe asthma. And she had an atrial ticardia coming from her high lateral right atrium. The phrenic nerve is right there. And she'd had lots of x-ray exposure over her life, already just being 23, and we wanted to minimize the amount of fluoroscopic exposure. So we were able to do this procedure on her in just a few hours, give a good result for her, and not use any fluoroscopy at all, save her x-ray for when it's necessary. This is a case of a patient who'd had a cryoballoon pulmonary vein isolation and had recurrent paroxysmal atrial fibrillation voltage mapping told the story here. Now, this is interesting because we usually think of the inferior veins as being kind of the weak link, especially the right inferior pulmonary vein isolation. The superior veins are easy prey. But in this case, it was just the opposite. We had a wide open right superior vein, not because of concern about the phrenic nerve, but just it was not well dealt with at all, a portion of the superior left vein as well. Voltage mapping after touching up with radiofrequency application showed good isolation and lack of spontaneous electrograms in both, you know, in all four veins. Endocardial mapping, by looking at the unipolar rather than the bipolar signal, has been used. Dr. Hutchinson in Arizona pioneered this many years ago, and inferring a low unipolar electrogram signature on the endocardium as being an indicator of lack of voltage, not on the endocardium, but on deeper surfaces such as the epicardium. So if the endocardium had good bipolar voltage, but the unipolar voltage was not good, that was an indicator that somewhere within the wall, midzone or epicardial was lacking voltage, and that was an indicator that there was action on the epicardium and ventricular arrhythmias. So here's bipolar endocardial and unipolar endocardial. And yeah, there's a lot of normal on the unipolar endo, but there's a lot of abnormal as well, especially these red zones here that seem to correspond reasonably well with epicardial mapping in this case. And the same projection here, kind of a slight right anterior oblique projection. Same patient with LAO projection. And this red zone up here, in fact, much of the anterior wall is not looking so bad. And this is an indicator that kind of an unusual distribution of scar, not just epicardial fat around the coronary artery. Now, I have a few questions to go through with this, during this little presentation. The first one is this, the 73-year-old woman with an anterior infarction and ventricular tachycardia comes for ablation of same. The left ventricular voltage map is shown during sinus rhythm. The exit site for the VT shown at the left, this is a sinus rhythm voltage map. It's not an activation map, sinus rhythm voltage map. So the probable site of exit for not the ablation site, but the site of exit of the VT shown at left, which is a left bundle branch block, right superior axis tachycardia is which of the following? You can pause and come back when you're ready with your answer. I'm ready. The answer is site C, down here at the apex. The reason for that is it's a left bundle branch block, right superior axis and a post-infarct patients. The exits from these are typically on the infral apical, leftward side of the septum. D is not correct because that's basal. Site A is anterior, should have an inferior axis. And site B is from within normal muscle, not scarred. You wouldn't expect such to be coming from there. Okay. Electroanatomic mapping can do a bunch of things. What can't it do for us? It can't provide direct information regarding tachycardia diagnosis or mechanism. It can be very suggestive that you have a Fogel process or macular entry, but I don't think one should rely on this, especially with a relatively limited map to be able to diagnose either of these mechanisms and therefore what the ablation site should look like. It can't necessarily identify the earliest site of a Fogel tachycardia. It can tell you which is the earliest site you've had so far, but there might be something earlier. So very dense mapping around a red spot that's surrounded by relatively concentric circles of later activation. That's a Fogel breakthrough from somewhere else adjacent to that, or a focus from right there. We'll see examples of how those can be distinguished. It can't definitely delineate where scar is. Certainly in past years, you can have a catheter out in the middle of a cavity, it shows no electrogram. Okay, it's a scar. Well, it's out in the middle of the cavity. Now you can test for that by using contact force to a large extent. It's pretty reliable for that. But it does definitely depend on some degree of contact being able to say whether you got a scar or not. It can't guarantee that you've done ablation at points where you said, I gave RF here. You can see indicators that you may have had affect electrogram reduction, change in tachycardia cycling. There's no guarantee that you will have a result of that. A delivery of RF energy translates into lesion made. A lot of people say I made a lesion here. Well, you don't know if you make a lesion there necessarily. You gave RF there, but did you make a lesion? That depends. It cannot provide freedom from complications. It can help, but it can't guarantee freedom from complications. It can't give you necessarily shorter procedure time. Sometimes they're actually longer because you have more detail at your fingertips. It's possible to make it shorter, but it's not a certainty. Here's my second question for you. This is two views, anterior and left lateral view of an activation map during an age of tachycardia in a 43-year-old woman. Earliest activation in the right atrium here is posterior to the HISS bundle as shown here. There's where the HISS bundle is located, these orange dots. Your choices, and here's the electrograms associated with that. The dashed line indicates the onset of the surface P wave during tachycardia. You should, with this information, ablate at 20 watts at this site, close to the HISS, use cryoablation at this site, map the left atrium, or just map a little bit more densely in the red zone. And you can join me when you're ready with your answer. I'm ready. So the correct answer is map the left atrium. There are reasons for this here. When you say to yourself, my earliest activation during this atrial tachycardia is at the HISS electrogram, that should call to mind several possibilities. One is a source in the right superior pulmonary vein on the left atrium, in which case the atrial electrogram timing of that earliest A in the HISS is not actually before the P wave, it's after the P wave onset, sometimes by a significant amount, because that's propagate from the right superior vein through the septum to that site. It could be a left septal source, in which case the HISS atrial electrogram is about 10 milliseconds or so before the P wave onset. Not great, but it's something. It could be a non-septal left atrial source, I mean, ergo mitral continuity, non-coronary sinus valve salvo, in which case the HISS atrial electrogram is maybe up to 10 milliseconds before the P wave onset. It has to propagate a slightly longer distance than some of these other sites. It could be a true pair of HISS and atrial tach, they do occur, but that should not be your first choice, especially if the HISS atrial recording is not more than 20 milliseconds or so before the P wave onset insofar as you can define it. Also, the large area of earliest activation suggests there's more of a point source, an exit from somewhere that's activating a lot of things simultaneously. So red is relative here. It's a relatively large area of nearly simultaneous early-ish activation. And you would not want to ablate here. Anyway, it's only about 10 or 15 milliseconds before the P wave onset, and it's got an R wave on the polar distal recording. There's nothing right about this. I want to go through 10 rules of electroanatomic mapping and how they can be used to your benefit. If you remember these, first is to set up the system correctly. Now, most of the time, you don't have to worry about this because the technologist or the representative for the manufacturer is going to be there and go through all this and do some minor troubleshooting. Reference patches have to be in good locations in order to cover the area that we want to. Or nearly, there's not much of a problem nowadays. Very, very large hearts can still be somewhat of an issue. If the patches are too far away, the chest is too deep, it may be difficult to see the mapping electrode for the system to be able to see it. Nowadays, with patches on the front and the back, that's usually not much of an issue. It's especially important with very, very large chambers. Think about a fontan, right atrium, very dilated left ventricle and myopathies. The system is very sensitive to patient movement. For long procedures where patients are going to have a difficult time staying still, general anesthesia is not a bad option. It's not a great option if you're talking about a focal process where the arrhythmia can be put to sleep as well. But think about this for some very good sedation and some anticipated long cases because even just shifting around a little bit on the table can make major differences in maps and destroy an hour's worth of work. The amplifier has to be turned on before the computer. In most cases, most labs just deal with that on their own. But sometimes you can't get the computer to work. It's not making any... You're not able to see anything on the computer. It's just so you're reviewing a case. Well, it's because the amplifier's going to turn on first. Be sure to carefully select which channels are going to be used and recorded. Maybe some very important things that you want to not miss and some not so relevant things that you don't really need to see. So make sure you're recording the right things and displaying the right things. Pick your reference carefully. And most of the time, again, the trained representatives from the manufacturer or your lab staff are going to be pretty good at this, but it's not 100%. The correct reference is one that's easy for the system to recognize and not ever make a mistake. It will be one that has a clean, sharp signal that's stable from beat to beat, not changing a whole lot. And from an electrode that's not moving around a whole lot, there should not be a lot of extraneous signals such as if you're recording a natural tachycardia, it shouldn't be a lot of ventricular electrograms in a coronary sinus electrode recording. That would be problematic. Surface ECG is a pretty reasonable reference for people with idiopathic BT. Nice, sharp, high amplitude QRS complexes, not easy to miss when they occur. So you have a triggering screen on the electron atomic mapping system and it gets that reference every single time and looks at your activation time as you're moving the electrodes around and saying, this is early, this is late. It's sometimes a good idea to pick a chamber where you don't think you're going to need to be doing very much for your reference. So for instance, if you are doing an atrial tachycardia, coronary sinus is a great resource for this. Usually the catheter stays stable. If you decide, oh, I'm going to put a catheter in the high right atrium of the atrial appendage as my reference and you're mapping a right atrial tachycardia, well, that's easily dislodged. If you're representing its presence on your electron atomic mapping system display all the time and you're paying attention to that aspect, you can say, oh, my catheter just dislodged. I'll get it back to the right location. If a representation had been saved at that snapshot or something like that. Otherwise you could be doing a lot of mapping with a moving reference and that's just not smart. If you've got a left ventricular tachycardia, the right ventricular electrode, that's not going to be disrupted by manipulating the catheters in the neighborhood or a sharp ECG peak is a good thing. If you don't have the correct reference, you can have a very distorted map because again, you're relying on that reference to be your gold standard. Everything is measured in reference regarding the timing of that reference electrogram. If it's not reliable, if it has two peaks in a coronary sinus atrial electrogram, sometimes it picks one peak, sometimes the machine picks another. You're 10, 15, 20 milliseconds off. Does that make a difference? Sometimes it does, sometimes it doesn't. If the ventricular electrogram is picked by the system during an atrial tachycardia instead of coronary sinus recordings, atrial recordings, that's a problem. If the wrong deflection of a surface ECG is picked up during VT, that's a big problem because now all of a sudden your sites are not making sense. One that is adjacent to another site, they're 20, 30 milliseconds difference, not because they're different, but because the reference was different. You're going to have problems dealing with these tachycardias that you don't need the reference to be a problem too. So here's a problem with the incorrect reference. Here's a coronary sinus electrogram that was picked as, we'll just make the reference there. This is an atrial tachycardia we're trying to map here, but the system picked the maximum negative voltage. You can pick the maximum negative voltage, maximum positive voltage, maximum positive dBDT, maximum negative dBDT. Systems vary as to what you can choose for this, but this is where it took the electrogram here. Well, that's great. It picked the maximum within the window of interest here, maximum negative within the window of interest, there it is, bingo. Unfortunately, that's a ventricular electrogram and we're mapping a natural tachycardia, that makes no sense. So if you pick a correct reference, this coronary sinus recording has a ventricular electrogram in it, but no way is the system ever gonna pick anything but this nice sharp peak that you wouldn't wanna, even if you didn't have this ventricular electrogram to deal with, you wouldn't wanna pick this one for your reference unless you had no other choices because it could pick this peak sometimes, it could pick that peak sometimes. That's probably 20 milliseconds, 25 milliseconds difference there. Could make a difference for you. Now, obviously, if you pick the wrong reference, if the machine picks the wrong reference, it takes the activation time correctly with the reference chosen. And in that situation, we had a map that looked kind of weird here. We had this diastolic, beginning of a diastolic quarter here, but there's no orange here, it's just kind of weird. And when it's picked correctly, we have a re-entry going in the opposite direction with a diastolic wavefront coming in the opposite direction as we had with the incorrect map, makes a difference. So that's the wrong one, it gets the wrong result. This is the right one, it gets the right result. Rule number three, pick the activation window. That is the portion of the tachycardia cycling during which the mapping system is going to collect information. Choose that correctly. You can avoid really bad errors in mapping by acquiring signals from outside your ideal window. I'll show some examples of this. For focal tachycardias, it's pretty simple. You can set this window. For a focal atrial tachycardia, you want something, the window to be maybe up to 50 milliseconds before the P-wave onset and not much after the P-wave end because nothing outside of that window is going to be atrial electrogram. So why have the entire cycling to cover? You're only going to run into problems. You're going to get extraneous ventricular signals, basic part of it, who knows what. So 15 to 100 milliseconds prior to a P-wave in an atrial tachycardia or a focal QRS complex. And at the end of the same complex, end your window and you'll end up with this extraneous stuff. Perhaps extrude artifact and signals that are emanating from the wrong chamber of ventricular atrium, opposite where you're actually mapping. For macro-reentry, the window should be set to pretty close to the entire cycle. You'll miss some important stuff, especially where you, if you set the window to begin at the mid-diastole, as the DuPonte method, as a lot of people do. I think it's a great method. It gives me a view of the electron atomic map that I'm familiar with, where the red is diastole and purple is the very latest site before reenters into red there. We're all familiar with that paradigm, so it makes sense. But you'll miss a lot of data if you only set it to 80% or 75% or something like that. Some really important stuff will be within that area excluded. With this method, 90 to 100% of the tachycardia cycle length, all sites that you are acquiring will appear once within the window of interest. If you have it too narrow of a window, you may miss some sites that are actually important. And importantly, if the window is too wide, if you just let the system default do it, some sites will appear twice. And are they actually later and actually early or none of the above? It gets weird. So here's macro reentry. Actually, these are both the same, all the same tachycardias here, just different portions of the arrhythmia. So if this were macro reentry, you'd want to pick a window that's roughly the same as the tachycardia cycle length. Within this window, the system will say, I'm going to look for signals on the mapping catheter and I'm going to look for signals on the reference catheter. That's my activation time of this relative to that there. So here we are, we are going to find a stable reference. There it is right here. And this nice clean signal, the peak of the CS910 electrogram. Then you find mid-diastole. Okay, so here's the beginning of this P wave. Here's the end of the prior P wave. Here's the middle of diastole. And say, okay, where's that relative to this? It's whatever it is, minus 100 milliseconds or something like that. And then the right side of your window then is the remainder of the tachycardia cycle length. So the cycle length is in this case, 233 milliseconds. And this is 130 milliseconds from here to what I say is mid-diastole. Then by the time we get back to the mid-diastole again here, this should be 200 milliseconds. Yes. No, 100 milliseconds. So this is 103 over here. This is 103. This is going to be 130. Obviously those numbers are off in this example here, but you get the picture. In a focal tachycardia, very different. You want to pick a window that is likely to contain only electrograms from the chambers you want to map. So for a focal atrial tachycardia here, we take the onset of the P wave and say, I'm going to look at stuff that might be as much as 50 milliseconds. Probably it's only going to be 30 or 40 milliseconds, but let's be generous. 50 milliseconds before the P wave. And I don't need to know about stuff that's after the P wave ends. There's nothing useful to learn there. All I can do is get messed up and say, oh, I got this ventricular signal there. It's way late. Is this reentry? No, it's not reentry. Proved it was a focal process before, deal with it. All right, so this is a focal arrhythmia here where the mapping signal only occurs once during each cycle. And it's a nice narrow envelope here. It's not the entire tachycardia cycle length, and you've excluded extraneous sites here. Here's an example in which the window is, for whatever reason, set too wide, longer than the tachycardia cycle length. You can see two electrograms here per window. And so there's two activation times during the window. It could pick this one. It happened to pick this one, which is even stupider because it's a ventricular electrogram. How much is wrong with this? Terrible stuff here. So we haven't excluded extraneous signals. We would have, just by chance, if this window were correct, it would have fallen about here. This electrogram would only occur once during the window, and we'd get the right answer. So do it right. Here's an example of this here. Correct window width here. We've got this nice, clean reference electrogram here. And our electrogram that we're interested in with the mapping catheter appears only once during the cycle here. And I put the activation here at the earliest onset of high-frequency activation, our gained-up signal. And so we get this activation propagation map looking like this, coming along, going around the right superior pulmonary vein and probably coming back underneath here. Now, the window is 350 milliseconds. There's that activation time there. So we have that to bring a record of propagation. Contrast that to when the window is too narrow. And whenever you tell the system to take information, it might designate this as SCAR. If it has a threshold of voltage beneath which it says, oh, there's no signal there, despite contact, it must be SCAR. But it might go ahead and take a point if it sees any kind of activity there at all, especially if it's very gained up. And that's a problem because there may not be anything there. Here's the electrogram. There's nothing here. But the system says, I found it. There's your spot. I'm going to plot it here. And now our activation pattern looks, what is this? It doesn't make any sense. I showed this earlier with an example that doesn't make too much sense. So the window in this situation is set to 147 milliseconds, whereas the tachycardia cyclic, that's 347. So we are excluding some sites here. And it picks this wrong site. We get an activation pattern that looks opposite of what it should look. Here's a window that's too wide. So now we have two cycles represented here. And which one of these do we take? Do we take this one, or do we take this one here? Hard to know. And you get this screwball pattern here where, golly, it's going this way and that way at the same time. It's going two ways around the right superior pulmonary vein and the circuit. No, that's just not. So the window's too wide. And our activation time is inappropriately taken here by the system. All right, question number three. This is a 63-year-old man who underwent a biatrial thoracoscopic maze procedure for treatment of atrial fibrillation. And he's left, oddly enough, with an atypical atrial flutter, cycling 310 milliseconds. This is a right atrial voltage map that we're doing in the EP lab. And based on the results of this map, you conclude that extensive ablation has already been performed in the right atrium. Additional ablation will likely be necessary in the right atrium. The data should be verified before proceeding with further ablation. Whether they capture tissue within the red zone, I see some red here, is unlikely with output less than 15 mA. And ponder this and rejoin when you have your answer. The correct answer is the data should be verified before proceeding with further ablation. Well, there's some living tissue here. Why should it? Let's ablate it as well. Join its red brethren. I don't think so. We've got a problem here. And the problem is that this is a voltage map. And I don't know that there are areas in the normal atrium that have 103.78 millivolts to them. This is a stimulus artifact that occurred within the mapping window. And the machine dutifully took the voltage. Every time you get an activation time, you get a voltage. Even when you don't have an activation time, you might get a voltage. So when you narrow the window to exclude this, you can't edit the voltage out, aside from narrowing the window down and saying, OK, I'm just not going to pay attention to whatever happened outside the window. Now we have a much more still extensive damage in this atrium, but not quite as extensive as would be represented over here. And so our maximum voltage in this atrium is not 103.78 millivolts. It's 1.61 millivolts. Makes a lot more sense. If you did not correct this problem, you'd say, OK, there's nothing to do in this atrium. Let's not even bother with this atrium. This must be in the left atrium where the action is. It was actually in the right atrium in this case. So even one wrong voltage point, we have 247 points represented. That's not a lot of this chamber by current standards, but it's a fair map. And less than 0.5% of the points were incorrect in this case. The whole thing doesn't make any sense. OK, rule number four. Pick your activation times correctly. We talked about the reference being correct, the window being correct. Now our activation times are the actual meat of the matter here. The system will try to pick an activation time in most cases. Choices are positive, negative, maximum positive, negative voltage, or the maximum dvd heat in positive or negative directions in the biocid system. Even if there's no signal, if it's noise, especially if there's noise or a catheter bang artifact or banging into an electrode on a pacing electrode on a permanent pacing system or a mechanical valve strut, you get an activation time. All activation points within reason must have operator oversight. And if it's correct, move on. Require more stuff. If it's not correct, it's best to edit it right then as opposed to say, oh, wait, I'll come back to this later. Just tag that so I don't come back to it later. Just get it right the first time. And because you might miss one if you decide to come back later, well, I didn't get that side. And so now you've got a messy math that doesn't make any sense. There's some problematic situations with that. One is in the case of complex electrograms, scar-based atrial or ventricular tachycardia, what is the correct activation time to take? The smaller your electrodes, the higher fidelity of the electrodes, the more reliable. Even the smallest deviation from the baseline can be, but you've got to be very careful about that and corroborate with surrounding signals. Sites on the annulus may have both atrial and ventricular signals. Make sure you take the right one. Sometimes it's confusing. One-to-one tachycardias, oh, they're very difficult, the one-to-one AV tachycardias. And if you're on the annulus, it's just hard to know whether it's atrial or ventricular. Multi-electrode mapping with hundreds of signals simultaneously brought into the system, you think it's a problem with just moving a single electrode around. Now you've got 20 times as much data coming in or more, and it's very difficult to keep track of that. It only takes one or two points. Like, it only took one point that was incorrect on our voltage map to make everything look stupid. It only takes one or two points with incorrect activation times to really mess up a map. So here's a case of a guy with not too many points on his inferior wall, posterior inferior wall of his left ventricle. That's what this is here. And it was during a ventricular tachycardia. The machine picked this time for I don't know what in the world reason, but it picked that time. It was a pretty gained up signal. We thought that that didn't make too much sense, but it looked like a focus with focal emanation from there. And then we're going to get a little bit, this is where these electrograms are taken in this situation. And when we do it with our choice instead of the machine's choice, it's a high frequency signal. Nice signal here. Now, all of a sudden, these sites become early and these sites become late over here. It looks like we have propagation through a channel. And it's not really re-entropy. It looks a lot more like, not really focal BT. It looks a lot more like re-entropy. It has to be confirmed with pacing maneuvers and all. But this is a first approximation that's a good hint. Here's a case in which automated activation was a little bit off again. It picked this site here during this. Our reference is correct. The electrogram is nice and clean. But it picked the peak dvdt up here. And there's a very high frequency component out here. This is not very interesting here. This is a lot more interesting. In fact, we have a unipolar that corroborates this a little bit better than I'm not sure why it picked this. Now, the Biosyn system uses actually unipolar signals to make the decision as to the activation time that display the bipolar signals. So that's machine pick and the user pick. This goes from being a not very interesting site to something that's actually before the P-wave onset over here. OK, this is one of my first maps with a multi-electrode catheter in the atrium. And we were just gathering signals like crazy. We got about 3,000 points. And it's coming from here or here on the top of the left atrium, the base of the SVC. No, it's coming from here, the top of the left atrium. No, it's actually coming from here, the left atrial ridge. No, it's actually coming from here, the cubitra-cuspid isthmus. Can't be coming from all those places. Or here, right superior pulmonary vein. All of those are red areas. But a problem here, and that's we got some wrong points out of 3,000-ish recordings. Can do it really fast. Great. Do it right instead of fast. Make corrections along the way. Reject a whole swath of electrograms or just not worth getting because they're artifact sweeping with the catheter or something like that. Rule number five, make sure your catheter has good contact. This should be obvious. It's a little bit easier nowadays, but it's not always as obvious. System always is going to record a voltage from the signal within the window that you've chosen. It says get a point, it takes a point. And it takes a voltage from that. If catheter tissue contact is not good, the voltage will be very low, simulating a scar. You try to pace from there, the pacing threshold will be elevated, simulating scar. If you try to ablate from there, it's not going to do much good because you're not in much contact. But activation times may not be very impacted. It may still look like a pretty good ablation time. And so you'll say, hey, I did all the things I was supposed to. Those idiots that talk about entrainment stuff, I did all that stuff, and I ablated there and nothing happened. So that's all junk. Well, you've got to apply the techniques correctly and get good contact before you start casting aspersions. There's a corollary to this. Extremely high voltage, like more than 15 millivolts, may be due to real data, especially in hypertrophy ventricle. I'm not sure I've ever seen much more than about 8 or 10 millivolts in even a hypertrophied atrium. So if you see something way out there, what's wrong with this picture? That doesn't seem right. It could be an artifact, a stimulus artifact, catheter-electrode contact with another temporary electrode, temporary catheter, or a pacing electrode, a valve strut, mesh from a colluder, all kinds of stuff. It could be ventricular tissue while you're mapping the atrium. You've got to be suspicious of this stuff. And when the question comes up, what's wrong with this picture? You've got to answer it. And then get a satisfactory answer and move on. Contact force sensing catheters, most manufacturers make these nowadays, have largely obviated this, but not uniformly. Here's a case in which we have transeptal access to the left ventricle. We're recording a left bundle, or maybe even his potential from the left side, right underneath an aortic mechanical prosthesis. So we're banging into that catheter. These are erratically occurring, very high frequency, stuttering electrograms indicative of contact with metal somewhere else. So when that happens, there's no consistent timing with it, they're very high voltage. Move away from the structure, which will rip it down. Now, this is an important application of contact force. This is an atrium. We're just getting the anatomy of this right atrium here. And you can see that we have this electrogram on the mapping electrode here. I don't tell you what the actual voltage is here, but it's a pretty good size electrogram. But low contact force in this system here. So what do you do? Get a little bit better contact. Hey, I'm at the edge of the atrium. No, you're not. You probably can go way off to over here before you actually end up with significant contact, 10, 15 grams here. So get contact before you say, okay, I've got the whole atrium here, or there's scar, there's not scar. As important, or maybe even more important than that situation is when you have no electrogram in a situation where there is adequate force. There's already scar there. Who knows why? There's scar there, and there's no point in a plating there in the vast majority of cases. All you can do is cause further harm. You waste time, fluid, if you've got an irrigated catheter and so on. It doesn't make sense to do that. The BioSense system and other systems give you an indicator of proximity of your catheter tip to a surface that has been previously described. So we've done a fast anatomic map of this left atrium here. And here's our ablation catheter in the left atrium. And you see it has a zero contact force measured at the tip. And various ways of doing that, whether it's a spring or optical sensors, and mechanical or optical. And in this situation, the BioSense system gives you no indicator that you have contact or not. It can give an indicator that this is bullseye configuration here. So it gives you an approximation of where the catheter projects onto a previously acquired surface. I'll get back to that. And as you move the catheter further in, it gives you, the rings get a little bit narrower here, and it gives you the contact force. It says, yeah, we're in pretty good contact with that prior previously described or inscribed surface. And now we've got really great contact here, 31 grams, and the circles are basically pancaked on top of each other. Now, this is an artifice of what your previously inscribed or described anatomy is. So you can wave a catheter around the very center of a chamber, not making any contact at all, and it'll make a shell of the anatomy there. And if you move this catheter towards the edge of that shell, it'll give you a bullseye there. It won't give you contact force. It won't register any contact force because you're out of the cavity. So it helps with that as well. But merely having a couple of points around in there, you don't know that you're necessarily up against a wall. We'll come to that subsequently here, like right now. It's important to delineate the entire chamber of interest in many cases. You can miss important areas of a right atrium or left atrium. If you never visited there because it was hard to get to or to the point of wasting the time to do that, it's especially important in congenital heart disease or atriotomy for atrioceptive defect repairs in the right atrium because those can be hard areas to reach here. You can suspect that you have incomplete chamber data when it looks like you've mapped the whole thing, but you've clearly got macroentry going. It's clearly in that chamber, but not much of the tachycardia cyclic does account for it. It's somewhere in there. Where is it? Well, it's a place you haven't mapped yet. If you're on fluoroscopy, you can see the shadow of the chamber or some catheters in there in areas where you've not been with the catheter before. So that's a clue. Not my handiest clue because I don't use that much fluoroscopy anymore, but it could be helpful. If on electron and atomic mapping, you have other catheters in the chamber, you can see these catheters, and they're in an area where you don't have any mapping data just yet. Well, they're obviously in the chamber. I hope they're in the chamber still. They're not outside the chamber, but they're outside the mapped anatomy, so go fetch some more anatomy. The chamber shape on the mapping looks weird. Doesn't look like a full chamber. Right atrius should look like a certain thing. Left atrius should look like a certain thing. Left ventricles are a little bit more variable. Right ventricles are very strange. And this is especially important with dilated chambers and hard to reach areas, such as the atrial tachycardias and the fontans or guys like that. It's good to sample pretty broadly at the beginning of the procedure if you can. Kind of get the lay of the land. What are the limits of the chamber? How far is the left ventricular apex away from where I am? Because you might think the left ventricular apex is at a certain point, and you're mapping over here towards the base, and you say, OK, my point is halfway between the apex and base, the mid-septum. Can you tell your partner that? Well, the apex is really over here, and so to him, the mid-septum is here, and you think it should be here. So telling somebody else where you are or telling yourself, in case you have to come back for another procedure, it's very important to know exactly where the chamber is. So in the right atrium, you get the superior and inferior vena cavae, the histolocation, coronary sinus, tricuspid anus. These are quick points. Doesn't have to be the whole chamber, necessarily. But the interlateral right atrium is a really tough area to get to sometimes, especially in that style. It can be pretty important in some cases. In the left atrium, the pulmonary veins and mitral valve. Right ventricle, apex, lateral base, tricuspid and pulmonic valve anula are reasonable things to do. And the left ventricle, pretty obvious. Here's an example of a right atrium, superior vena cavae. This guy looks kind of sad with his vena cavae just kind of hanging over him like that. Needs to be watered, I guess. Here's the inferior vena cavae, and the body of the right atrium looks a little odd. And it turns out that if you put in a tricuspid annular catheter, that's in the atrium. And we don't know about all this stuff here. So if you fill in some of the blanks there, oh, there's a lot of atrium here. In fact, this guy had an atriotomy that was kind of on the downside here. I don't know why, but it was there. Completely missed over here. So delayed as much of the chamber as you can. Rule number seven, there's 10 of these. Account for the full cycle length of re-entry to arrhythmias. For MAC re-entry, you should be able to identify in every point along the circuit, if you try. If you don't care to do that, that's probably OK in the ventricle, certainly. But in the atrium, it's nice to get pretty much the entire circuit, including small mid-diastolic corridors. You may not get the full picture of the arrhythmia or the course of the impulse that it traverses without accounting for nearly all of the cycling. Corollary to this, if you made a thorough attempt to obtain the entire cycle length from one chamber and it just is not there, make sure you've reached all the areas of the current chamber or check for the other atrium you may have by appropriate entry. For instance, recording the entire cycle length in a chamber, however, does not mean that that chamber contains a re-entry circuit or that re-entry is even what's going on. It just says there's a lot of slow conduction going on, perhaps. Hopefully, it's in that chamber, but it may not necessarily be. So here's a case of a lady who's had a pulmonary vein isolation and is left with an atrial flutter with a cycle length of around 270 milliseconds. This is a posterior view of the left atrium. Got a few points on there. And each of the activation times has been verified. These are correct, not spurious. Based on the information from this map, as you have it, you conclude that we have a macular re-entry in the left atrium. We have a focal tachycardia that arises from the bottom of the left atrium, emanating from there. We have significant slow conduction in the left atrium, or you can't conclude anything. Rejoin map when you're set. Correct answer is we've got slow conduction in this left atrium. Now, the entire cycle length is covered here, right? We have 270 milliseconds. We have 272 milliseconds showing up here. So the entire cycle length of tachycardia is covered. Doesn't mean we have re-entry in this atrium. Doesn't even mean that we have re-entry. It does mean that we have slow conduction in this atrium. At least that. We can conclude that. So D is wrong from that perspective. Here's the right atrium in the same person. Again, the entire cycle length is covered. And we have early meets late. We'll talk about that in a second. At the hiss. Too bad for this, huh? No, this is actually right atrial tuberculous. But this is where your window is. We'll come to this subsequently. The way your activation pattern looks is a function of where you say the window is during the cycle length of the tachycardia. This is very important. And you can get pretty messed up. So this is ablation. The CTI terminates the arrhythmia, which was re-entry, but not in the left atrium. Rule number eight, beware of changes in tachycardia. Changes in tachycardia from one to another in scar-based arrhythmias are the rule, not the exception. Multiple tachycardias are found in both atrial and ventricular arrhythmias in the presence of scar. And you may change from one to another during mapping and or ablation. Recording systems can help detect changes in tachycardia, not the mapping system. This is your recording system. I know a lot of places only rely on the electroanatomic map. They have a stimulator, but they don't actually look at electrograms so much. This is a problem in some of these cases because you may miss important changes in tachycardias because you don't have enough electrograms. With atrial tachs, you can have multiple intracardiac recordings with VT at all 12 surface ECG leads. I have them all showing all the time on all of my VT cases, all 12 leads, because I don't want to be fooled by a change somewhere along the way. Mapping systems, however, display limited information, just a couple of surface ECG leads, just a couple of intracardiac recordings. So the system doesn't get bogged down or don't get distracted by too much stuff on the screen. Under these circumstances, it's harder to detect changes among tachycardias just with a mapping system. You can spend 30 minutes mapping and get some very confusing activation patterns because you've been mapping tachycardia 1 that switches to tachycardia 2, which is different, that switches to tachycardia 3. You've got this agglomeration of data on there. Doesn't make any sense. Don't do that. The solution is to pay attention to both the recording system, where you've got a lot of electrodes reporting, and your mapping system while obtaining the activation map and be alert for activation and especially cyclone changes. So here's a case. During RF application, during an atrial tachycardia, a big deal, doesn't seem to make much of a difference here. Maybe there's some oscillation in the cyclone. Well, here's some additional recordings here. And here's a cycle with a P wave right in the middle there. And you see that the HisA is slightly earlier than the distal to proximal coronary sinus activation. That persists for a couple of beats until it doesn't persist. And now the tachycardia changes right here to one that has the HisAs timing sort of with the P wave here. But now the CSs are earlier than, or maybe later than, I don't know, but they've moved earlier in the window. And they're now proximal distal. This makes a difference. And if you didn't, if you're only mapping off using the mapping system, you might get only these recordings or not even this and say, OK, I know what's going on. It's the same tachycardia all along. Maybe it slowed a little bit. Maybe we did something. Let's keep ablating. You're on a different tachycardia here. Rule number nine, red dots are not the same thing as effective ablation. Boy, this just should seem obvious, but it's not to a lot of people. It's pretty easy to make a nice clean line of red dots for linear ablation. It's really easy to do. You just have to edit some stuff, say take a point when we're there, decree that you've had an ablation. Really, you haven't necessarily done anything there. So it doesn't mean you've had an effective tissue ablation. It doesn't mean you've done any ablation, actually. You just had a point registered. It looks like you've been there. And so which point was real, which one wasn't, that's hard. You can corroborate effective ablation with electrogram degradation, a decrease in impedance by 10, 15 ohms or more. An effect on the tachycardia, it slowed or it terminated. Or sometimes you can use a unipolar electrogram showing ST elevation after ablation. You've done some damage there. It leaves that signature behind. Or an R-wave that develops in the unipolar atrial electrogram, indicating that there's nothing emanating away from that site. Dwell time, contact force indices, sure point, ablation index, force, time, end roll are all different mechanisms to tell you, yeah, you probably actually did some ablation there. So here's a case, back of the left atrium, kind of innocent looking here. And here's some pulmonary vein isolation lines. Super. Red dots look great. Well, you can sign up Zorro. You make the sign of JMM, that's me. You sign your name. That means you've done ablation. Hopefully you haven't. This is the so-called VZ tag. It's an index of how much time was spent at any given location. It doesn't say that ablation occurred there. It's just how much time was spent with the darker red, indicating a longer time in this case. This is so-called breadcrumbs. It's a different means of displaying the same data. And this is wherever the catheter was roaming at the time. You see it wandered into the carinae here a little bit. But spent most of the time out on the line where it should be. And this is a combination of these. You can display these a bunch of different ways. You can have them not shaded, shading to indicate the likelihood of having done an effective ablation or lesion there. This is so-called SurePoint algorithm. And it combines a lot of different information and integrates it into this SurePoint number here, 432. That's a pretty good number. On a posterior wall, it may be 500, 450, or 500. On the anterior wall or ridge are good. This lasts for 8.57 seconds with maximum power, 50 watts, so on and so forth. So this algorithm is a proprietary industry algorithm uses power, contact force, duration, impedance to give an index of the likelihood of having an effective actual area of damage left behind. Rule number 10. Remember that you are in charge of this case, not the machine. Don't be led around by the nose by a machine that is great technology, but only technology. You determine where activation time should be assigned. Machine has its idea, but you have the right idea because you know electrophysiology machine doesn't. Look at enough beads to get good data and make sure it's not a PAC or a PVC or a catheter movement or something like that. Edit erroneous machine-derived activations when they occur. Lots of important sites for macroentry have very low voltage that might be characterized as SCAR by the system, but it actually has information there gated up enough to be able to see what's going on. You have to correct erroneous points on voltage maps, as I showed the pacing artifact. You determine tachycardic mechanism and therefore ablation site characteristics. You decide the best ablation strategy, whether it's focal, linear, and where. And to that end, the DuPonte method of assigning during every intraday arrhythmia, splitting diastole down the middle. Red is at the very left end, and purple is the very right end. So where red meets purple is a diastolic corridor is an arbitrary thing. It depends on where you say the window begins here or the window ends there. See examples of this. Not always the best ablation strategy to ablate where red meets purple. So here's an example. This is perimicrobial reentry. And this is using the coherence system from BioSense. This is an activation representation of activation around the mitral orifice here. Cycle length is about 300 milliseconds. So this is perimicrobial reentry. And red meets purple. Early meets late. Let's ablate. It's a great formula, but it works. So let's ablate the lateral mitralismus over here. Super. All right. Well, you can change the window and have early meet late down here. Red meets purple. Ablate? Nah. Doesn't make any sense. Where are you going to connect? The anterior mitral annulus all the way around? OK, or over here? Well, you're probably not going to hurt anything. That might be an anterior mitral long line. Some people prefer that. Or how about here? Anterior wall. That's weird. And this is just manipulating this thing. This is this same map over here. And I'm just going to show you what happens here. If you manipulate this business up here, you can get red meets purple anywhere you want. Doesn't mean that's where the circuit is. It just means that's where your system has taken each activation point with reference to the reference electrogram within the designated window of interest that you have described. Here's a case. Again, early meets late. It's great. 77-year-old man with prior PV isolation. And it did a right atrial CTI line. I guess it didn't do a very good job, because it looks like we've got reentry around here. The entire cycle length is covered of this tachycardia. And so that's wonderful, except that it wasn't that. It was actually a focal elimination from the CS os. And again, ablation of the CTI here accomplishes nothing. Doesn't do any good anyway. Fluid overloads the patient a little bit more. So this is focal propagation. And the circuit time around the annulus was very similar to the activation to the cycle length of the tachycardia. So beware of this, especially around the tricot spin edge, especially when there's been a previous CTI done. And you've got something going on from the left atrium to the right atrium. It's passively activated. It has to go around this way. Rule number 10 continued. Remember, again, that you're in charge, not the machine. Don't be afraid to ask, what's wrong with this picture? Why do we have no volts in this chamber? I thought I recorded some electrograms here and there. I guess not, because the map is red. OK, you've got a wrong signal in there. It's 150 millivolts or something like that. But the activation times are all screwball. Well, the reference is picked wrong or something. When you have something that doesn't make sense, ask what's wrong with this picture. Figure it out. Maybe there's nothing wrong. But maybe there is. And if you figure that out, then you can move on. Anatomy isn't making sense. Voltage is out of line. Activation times don't make any sense because the reference or activation time is incorrect. Or you're sampling a paste feed or a premature complex. Now you're in a different tachycardia as opposed to the original one that you thought. Lots of problems. OK, so our 10 rules. Set up the system correctly. Pick the reference wisely. Designate the activation window intelligently. Denote activation times correctly. Make sure you have catheter tissue contact. Delineate the entire chamber of interest when mapping. Account for the full cycle length of the tachycardia in macro reentry. Be aware of changes among tachycardias. Or certainly not termination, but changes from one tachycardia to another. Remember that red dots do not denote effective ablation. And remember that you are in charge of this procedure, not the mapping system. It cannot tell you mechanism. It cannot tell you which is the tumor of origin. It cannot tell you what ablation strategy you should do. You have to develop all these yourself. In summary, electron atomic mapping systems have revolutionized the practice of ablation. They've led to improved efficacy, improved patient safety, improved operator safety with less fluoroscopy, and probably shorter procedure times. It enables us, they have enabled us to do procedures that were just not on the map, so to speak, 20 years ago. However, these technologies must be used carefully to avoid significant mistakes. They can't make a diagnosis or guarantee efficacy or freedom from complications. Future technological advantages may further improve accuracy and reliability of systems to further aid us to move forward in our procedures and of our discipline, such as automated reference assignment, ability to map multiple PVCs without continuously switching between maps, which requires information on all of these and plots the appropriate map, potential for mapping localized sources of atrial fibrillation, such as foci or rotors, high-density mapping tools, electrodes, and or catheters, improved annotation algorithms to make them more accurate, can record more data safely and reliably without concern about whether you're picking up junk or not, improved delineation of block versus slow conduction zones, practically limitless number of acquisition points available and multiple maps, networking of cases for collaboration and or research, and even more things. These are things that are here and now that I didn't have time to go into but are certainly capable within reach or soon to be evident in all mapping systems. Thank you for your attention, and we'll join later. Thank you.

Electro-anatomic mapping

electrophysiology procedures

anatomic reference

activation mapping

voltage mapping

ablation locations

BioSense Carto system

relationships between anatomical structures

scar tissue identification

electrode or catheter location monitoring