So welcome back to interrogation part two. At this point, we're gonna pick up with our B of PBL stop and battery status. So when we're looking at battery status, this is something that's really important to do with every device interrogation. It's one of those things that's also easily missed. And so I wanna spend just a little bit of time here and I also want to just reiterate, this is the importance of having a structured follow-up plan where you're doing the exact same thing for every patient every single time. There are a few things that we never wanna miss, battery is one of them. So let's talk about a little bit of nomenclature. Every manufacturer is a little bit different as they document things and call their battery statuses. But as a general rule, BOS means beginning of service. So it means the device is new, hasn't run out at least 50% of its battery, is doing just fine. MOS is middle of service. And then ERI or RRT is elective replacement indicator or recommended replacement time. Those two indicators or think about those as the gas light coming on in your car. It doesn't mean that you're getting ready to run out of gas and be stranded on the side of the road. It does mean in the next 50 miles, you should probably find a gas station. And so device manufacturers have set up devices with that same thought in mind, that we want to give patients enough of a heads up that they can get to their generator change without losing essential pacing function. So normally when devices trigger elective replacement indicator or recommended replacement time, we have three months from that indicator being tripped to EOS, which is what the device is gonna call end of service. Oftentimes devices will actually last longer than that and function appropriately, but the manufacturer's strong recommendation is that you get these devices changed out within three months of the device reaching elective replacement indicator. This is also a really good teaching point for your patients. They will be able to see their interrogations through their patient portals and sometimes can get very nervous about seeing their battery voltage nearing ERI or nearing RRT. And so as you have those conversations with them, just reassure your patients that the device manufacturers have built in a safety net of three months. And so we really do have time to get the device changed out and there is no rush, but patients can really stress over that piece once they're able to see that information on their portal. The other thing to look at when you're looking at battery status is trends. A lot of devices right now are on manufacturer recall for various reasons for battery. And so looking at the last interrogation, looking at this interrogation and making sure that the battery status is trending in a way that you expect is also very, very important. There are some things that have impact on device longevity. Some of these we can impact, some of these we cannot. One of them is electrogram storage. And so if you have a patient with a lot of episodes, that's gonna eat up that device's battery and perhaps limit the patient's battery on that device. Another one is lead impedance. Dr. Ard reviewed that a higher lead impedance is gonna help preserve battery. A lower lead impedance is gonna actually drain more battery because of Ohm's law. Thresholds and output programming are very important. I'm not gonna spend time here now on that because we're gonna talk about that in just a little bit. How much the patient paces will also impact their battery and how quickly that battery drain occurs. And then high voltage therapy. So if you have a patient who has VT storm and receives a lot of high voltage shocks, that certainly can have an impact on the battery. You can also, if needed, use a magnet to determine battery status. That's only for pacemakers though. And it's very rare that you would ever have to do this, but it is something that can be done if you're with a patient and you don't know what kind of device they have. Each manufacturer has their own set magnet rate for normal battery function, elective replacement indicator, and also RRT. And so by putting a magnet on a patient's device and observing the behavior, you would need to have a surface electric cardiogram hooked up while you were doing that. You could tell what manufacturer the patient had for their device. So let's think through just a few of these examples. So this is an example where you don't get a battery voltage anymore. It just says device at ERI. It will also tell you that ERI condition is reached. Most energy intensive features are now disabled. This happens in some manufacturers. And so for example, they would turn off electrogram storage. They would turn off rate response. If you had any other programming on that might drain the battery, they would turn those off to save energy to make sure that the patient had a really strong safety net to get them through to generator change. This is another example of RRT. And the observation here just says replace device less than three months to end of service. Here's an example, and one that I really want you to be aware of. Medtronic pacemakers, they're the only ones that do this. But Medtronic pacemakers, once they reach RRT, they change their pacing mode. So if you had a patient that was programmed, for example, DDD, and their pacemaker reached ERI or RRT, the device to save battery is gonna change their pacing mode to VVI 65. So if you ever have a patient who presents and they're not feeling well, or if they call you and they say, you know, I'm just really not feeling well, and their battery was nearing ERI, think, have they reached ERI and did their pacing mode change? You can imagine if you had a patient that was programmed for both atrial and ventricular pacing support, they got switched to a VVI mode. And we remember that that means the ventricle is being paced, the ventricle is being sensed, and we're gonna inhibit pacing based off of sense events. That could seriously impact how they feel. They've lost their atrial kick, their rate is now fixed, they have no more rate response, we're not paying any attention at all to the atrial chamber. So just something to keep in mind. These patients are actually ones that we would choose to change out more urgently, not because they don't have time before EOS, just because they have symptoms related to being VVI paced, and we want to go ahead and get their dual chamber support back in place as soon as possible. With some Medtronic pacemakers, you can bring the patient in and reprogram them back to DDD. Some Medtronic pacemakers you cannot. Important to just revisit that with your industry representative, they can walk through all of those options with you based on your patient's scenario and the device they have implanted. This is the graph of the rates that patients have whenever you place a magnet over their pacemaker. I'm not gonna walk through this, but this is important to have and to know. All manufacturers can provide you with this information, but again, if you ever don't know what kind of pacemaker a patient has, if you just took them up to a surface ECG, put a magnet over their device and see what the device does, you can use this form to figure out what manufacturer they have. Let's move on to lead status. So when we think about our lead status evaluation, there are three things that we want to keep in mind. The first is what is the lead impedance? And I know Dr. Allred went over that in great detail, so we're not gonna spend a ton of time here, but it's the measurement of resistance down that lead. And normal impedance is 200 to 2,000 ohms. We also wanna make sure we're looking at trends. Much like our battery status, we wanna make sure that our lead trends are also stable or behaving in a way that we would have expected. So for impedance decrease, we wanna consider an insulation breach. For impedance increase, we wanna consider a lead fracture or a header connection problem. Lead impedances should be stable. This is the one time for your patients that a flat line is a good thing. You want them to be flat and stable with really no changes. We also wanna keep in mind as we're looking at our lead status, are the patient program unipolar or are they program bipolar? Unipolar lead impedances are going to tend to be lower. Bipolar lead impedances are gonna tend to be higher. So just things to keep in mind. So let's look at a few examples. This is an Abbott device. Our atrial lead impedance is at the top. Our ventricular is at the bottom. You can see that we've got some guardrails on these graphs with our 200 to 2000 ohms. And you can also see that that's where our lower and our upper limits are programmed. Your lower and upper limit for your lead impedance alerts are programmable within the device. And so that's very important to know. For example, if you had a patient that you were worried about their lead and they were 800 ohms and they had gone up to 1200 ohms and you're like, okay, well, something's not right. I don't really wanna wait till we get to 2000 ohms to be alerted. You could certainly change the upper limit of that alert down to 1500 ohms so that you could be notified of that sooner. So just things to think about. The other thing as we think about these lead impedance trends, again, flat lines are good here, but also importantly is there is a huge range between those lower and upper limits. And right now we don't have any devices on the market that would tell us that a lead impedance changed 200 ohms, for example. So as you're looking at these things, I want you to really think about what do I wanna know about for this patient? Usually 200 to 2000 ohms is sufficient as boundaries and as our guardrails, but there will be situations like that patient we just talked about where they might be creeping up a little bit and you want to be notified sooner should they cross that threshold. I just wanna encourage you that the 200 and the 2000 ohms are not settings set in stone. You can program those as needed for your patient. The other interesting information on here is that it tells you which pulse configuration is programmed for both our atrial and our ventricular lead. Both of these are programmed at bipolar and it also tells you what's gonna happen with lead monitoring if one of those thresholds is crossed, those 200 or the 2000 ohms. So for our atrial lead, it's just gonna monitor it. Nothing would change. So if our atrial lead impedance went to 2,500 ohms, it's gonna stay bipolar and nothing's gonna change. If our ventricular lead impedance, however, did the same thing, it's gonna switch polarity. And so if we're bipolar, it's gonna go to unipolar. And if you remember from Dr. Allred's lead talk, that means that we're bypassing a piece of that ventricular lead and going back to the CAN because oftentimes if we have a problem in bipolar mode, we won't have that problem in unipolar mode. We can save that lead, still safely give care to the patient without requiring a lead revision. So let's look at another example because there's a lot of information on these graphs. So this is a Boston Scientific device. You can see that we've got two pieces of information on this device. The first is intrinsic amplitude and the second is our ventricular pacing impedance. On this one, the guardrails for this device are set at 700 to 2,100 ohms for the graph here. For this, that's not where the alerts are programmed to. That's just how Boston is graphically representing the changes in impedance. So you can see we have that gradual rise in lead impedance and then an abrupt drop and then it stables out. Same thing for our sensing. We're pretty stable, but then an abrupt drops in sensing. So what do you think happened here? My guess looking at this is that the device was programmed to bipolar pacing and bipolar sensing. The bipolar piece of this lead had a problem and so the patient was seen in clinic and changed to unipolar. Remember we talked about unipolar impedances are gonna be less than bipolar impedances. Same way, unipolar sensing is gonna be less than bipolar sensing. And so as we look at this, that's my best guess of what happened here that it was recognized that the patient was having a problem with their ventricular lead. They were brought into clinic and then the device was reprogrammed. And you can see that everything is okay in a unipolar pacing mode. So we have stable lead impedance and stable sensing. So we're able to save this lead without having to do a lead revision, which is very important for the patient. Let's look at another example. So on some manufacturers, this one is Medtronic. You might have two separate trends. So you might get your bipolar and also your tip-to-coil impedance. And so this is also really important information because if you're trying to troubleshoot understanding which pacing configuration is programmed on, are we programmed bipolar? Are we programmed tip-to-coil? But then being able to evaluate this information and use that information for optimal patient programming is really helpful. So as you're looking at your lead impedance trends, make sure that you understand, are we looking at more than one configuration or are we only looking at the configuration the patient is currently programmed in? The other thing that Medtronic does in their interrogations is that they will give you the last 14 days individually. So you see that you've got this trend here and we've kind of changed the dates to protect patient confidentiality. But the trend is gonna be month over month, but then those last 14 days are actually days. And so if you're looking for a recent change or a specific issue with a patient, then you can look at the last 14 days and get those actual readings. Here's another example of a lead impedance trend. This is our LV lead impedance. And you can see here that we're at 200 ohms. You can also see that it's in that black box, which is the device telling you that this meets alert criteria. So the device is saying, you've told me to notify you about that. So I'm letting you know we're at 200 ohms right now. Depending on the patient, this might be okay. And so, like I said, there's no one right way to program a patient. There's also no one right answer for every patient's lead impedances or thresholds or sensing or anything else. Oftentimes, when we think about device follow-up, less is more. The trend here is fairly stable. And so depending on your EP and how they feel about this trend, they might choose to just monitor this. They might choose to change the LV pacing configuration to see if we could get a different impedance value. The biggest thing to know here is that if you see this, it's your job as the device evaluator to bring this to the attention of the physician so that they can make a decision about how they want to handle this in this certain patient. Here's another example, another Boston Scientific device with kind of a sudden impedance drop. Again, may have been a programming change because we settled out after that, and that's what makes the most sense in these situations. So now let's move on to sensing. I know this feels like a lot, and it is a lot. Your job as you look at device patients is very important, and I want you to take this very seriously. And so as we think about all of these things, again, it's important to make sure we've got this structured follow-up in place and that we're doing the same thing for the H patient every single time. So sensing is what we looked at on that first part of our P section, which is what the device is seeing. So we're looking at our P and our R-wave amplitude. And as you evaluate your sensing numbers, a normal P-wave is greater than one millivolt, and a normal R-wave is greater than three millivolts. Again, trends are very, very important here. We also want stable trends, flat lines for these things. Also important to keep in mind, are we unipolar? Are we bipolar sensing? One other important caveat is that you can have a sensing configuration that's different from your pacing configuration. So for example, you can tell a device that you want it to pace bipolar but sense unipolar. And so it's important to know what you're looking at as you look at your numbers and your trends. And then finally, we can use our wavelet template. This is mostly in our tachy devices. But this template uses a stored EGM to discriminate supraventricular tachycardias from ventricular tachycardias. Incredibly important for our defibrillator patients. We do not want them getting inappropriate therapy. And so wavelet is able to use a normal EGM, compare it to a faster heart rate, and say, OK, is this rhythm more likely to be supraventricular or ventricular in origin? An important thing to note as you see patients in the office, if they have wavelet programmed on, it is very important to verify that the match at that time matches their presenting EGM at follow up. That's one of the things. Every time, every patient, no matter what, if wavelet is on, make sure you're updating that template or at least looking at your match scores to make sure that that hasn't changed and that we don't need a new template uploaded. The one time that you might not want to use wavelet, just as a side note, is if a patient has an underlying bundle branch block, because our ventricular arrhythmias are also going to be wider in nature. And so if a patient has a left bundle at baseline, you might want to turn wavelet off. Just something to think about. So let's look at a few sensing evaluations. So this is a Medtronic device. P waves at the top, R waves at the bottom. It's very helpful that the device tells you what the sensitivity is set at. So for both of these, our sensitivity is set at 0.3 millivolts. And our last measured P wave was 3 millivolts. And our last measured R wave was 4.5 millivolts. So both of these are very, very acceptable sensing measurements. We want to make sure that we have a safety margin built into place. So for example, if your sensitivity was 0.3 in the atrium and your P waves were measuring 0.45, we might worry that we would not capture all of the atrially sensed events. Both of these leads have a very high safety margin. So we've got lots of room here to work with. But something that's really important to keep in mind, and we're going to talk about safety margins more when we talk about threshold evaluation. Here's another example of a sensing test. This is an Abbott device. So interestingly here, it will tell you that the device is programmed RV bipolar. So that's nice to sense. It will also give you the range. So 11.7 to greater than 12 millivolts. And the trend is OK. I don't want you to get worried about those few little drop downs, especially in ventricular sensing trends. The reason is, is because the device is also sensing things like PVCs, which may be coming from a different direction and might have a different sensing amplitude. Overall though, this looks very stable. Here's a good example of that. So this is from the same patient. So their R-wave amplitude trend up here is up at the top. And then their histograms are down here at the bottom. The reason I included both of these, we can see that the patient primarily atrially senses, primarily ventricularly paces. This is really important because I would not expect for our R-wave amplitude trend to be accurate at all because we mostly have V-paced events. And so while you see these wild swings in R-wave amplitude, what we know is that the patient mostly V-paces. And so that's probably OK because it's not going to be as accurate as if a patient was V-sensing all the time and the device had a lot more events to measure that sensing off of. OK, let's move on to thresholds. So what is a threshold? So a threshold is the minimum electrical stimulus needed to consistently capture the heart outside of the heart's own refractory period. The most important word here is consistently capture. So we have to make sure that when we're doing our threshold test that it's not one beat and then we miss another one. That's not their threshold. We've got to go back up to where they're consistently capturing their heart. Auto-thresholds are a feature within most devices now where the device will automatically monitor the pacing thresholds and adjust their output to ensure adequate safety margins if they're programmed on. Again, safety margins is something that we talked about with sensing. Very, very important with thresholds as well. You want to make sure that you've got at least a two-time safety margin on voltage when you're thinking about thresholds. Trends are important, unipolar versus bipolar, exact same comments as before. And then we always want to compare our measured thresholds while we're seeing a patient in the office to our programmed outputs to ensure an adequate safety margin. So when we think about safety margins, again, they're incredibly important because they allow for changes in thresholds over time. There's data that shows that thresholds vary based off a wide variety of things. Has the patient eaten? What medicine are they taking? What time of day is it? They don't vary a lot, but they vary a little. And so that's why we want to make sure that we've got this safety margin built in so that if there are those small variations and thresholds, the patient has adequate pacing support and we know that we're going to consistently capture their heart. There's also acute versus chronic safety margins. I want you to think about a new implant, for example. So a patient just had a lead implanted. Those leads are normally screwed into the heart tissue. Imagine all the inflammation around that. And then a scar is going to form over that lead, encapsulating it over time. Typically, that takes a few weeks. But as a patient is having that inflammation, having that inflammation die down, and then that scar tissue form, they need a higher safety margin than chronic thresholds. So even if their threshold is 0.5 volts, for example, at implant, we're still likely going to program their output to 3.5 volts until we see them back at that three-month mark. At that point, they're considered chronic leads. And we would feel much more comfortable decreasing that voltage to 2 or 2.5 volts, depending on your physician preferences. And we've talked about how the thresholds might change based off of metabolic abnormalities or medications or the other things that we've already discussed. So as we look at thresholds, this is a very, very good example. So this is an Abbott device. It's a new implant. We know that because we don't have very much data here. We can also see that the device is programmed to pace bipolar. And if we look up here under Capture under Test Results, the device is saying, I can't measure this threshold. That 0.875 volts at 0.5 milliseconds, that was the last threshold the device was able to measure at the last monitoring periods that could have been at implant. But today, it's saying, I can't measure this threshold. And so what Abbott does, if you have this safety feature programmed on, it says, if I can't measure a threshold, I'm going to go all in. And so 5 volts is a very, very high pacing output. But it does that to try to ensure patient safety. And so a few things could be happening here. The threshold really could be low and normal. And because of rate or arrhythmias, the device just can't measure it. And that would be OK. So if that happens and you check it again, you're like, no, really, the threshold really is 0.875. One option would be to turn AutoCapture off and set their threshold to a fixed rate as opposed to having AutoCapture on. Another option would be to say, well, let's leave AutoCapture on and just follow these trends over time. When we see them back in the office, we can reevaluate. But if you remember, we talked about impact on battery status. And voltage and output is one of those. And so once you go over 2.5 volts in your output for pacing, you're going to double the hit it takes on the battery. So that's just something to keep in mind. Sometimes we can't avoid it. But if we can keep our pacing output below 2.5 volts, that's best for our battery status. OK, let's look at this example. So assuming that LV pacing threshold for each of the LV pacing polarities are similar, which LV polarity will best preserve device longevity in this case? So I threw this in here. And this is going to take us back to impedances. But that's good because we also need to think about this. We also haven't really talked about all of our LV pacing configurations. That's going to be more of an advanced topic. But just so you know, whenever you have an LV pacing lead, there are often many, many, many variations of pacing that you can program these things to. So you can program it true bipolar, LV tip to LV ring. You can go LV ring to RV coil, LV tip to coil, lots and lots and lots of options. So if our thresholds are the same and we know that thresholds affect battery and we also know that impedances affect battery, if we look at all these options, which one would we choose if we were only looking at device longevity? So if you remember from Dr. Allred's talk, the higher the impedance, the less battery drain that we have. So for this patient, I would say that our LV tip to LV ring with that 627 ohms, that true bipolar, is going to be the best pacing configuration to preserve battery. OK, last one for this section. Let's talk about observations. This is going to take a little bit because there's a lot to cover here. So whenever we get to device observations, there's a few things to think about. There's the arrhythmia episodes we're going to talk through both atrial and ventricular high rate episodes. We're going to talk about how to evaluate our AFib episodes. And we're going to talk about other diagnostics that we have. So let's start off with our arrhythmia episodes. So on each interrogation report, whether you've seen the patient in the office or you're looking at a remote interrogation, at the bottom of that front page, there's going to be a section called observations. These are really, really, really important to look at. Because even though we have this structured follow up, we want to make sure we don't miss anything. And this is the device's way of saying, hey, you might want to pay attention to these things because I've noticed them. Or you've told me to pay attention to these things, so I'm letting you know that these things occurred. So in this example, we have five observations. So the first one is that the total B pacing was less than 90% for seven days. So for this patient, I would think that they have a CRT device. And we've wanted to know if we're not CRT pacing greater than 90% of the time. So that's a good one. We also can see that we've had AFib more than 0.5 hours for seven days. Our ventricular sensing episodes averaged five hours a day since the last session. And no wavelet template has been collected. There is a lot of information here, a lot to go into. And all of these are different issues, but they could all be the same. So let's take this one for example. So we see that our CRT pacing is effective less than 90% of the time. Also matches with our B pacing less than 90% for seven days. And that's interesting because we also have B sensing events and some atrial fibrillation. So with no other information, with just these observations, my guess would be this patient's gone into some sort of paroxysmal atrial fibrillation with a rapid ventricular rate, or at least a ventricular rate higher than their program pacing rate, which is causing them to not CRT pace. So these things give us a clue as to where we go next for our device follow up and what we take a deep dive into as we're looking at optimizing this patient's device. Let's look at another example. So this patient had, this is first of all an ICD. We know that because we have treated episodes up here at the top. So no VF episodes treated, no VT episodes treated. When we look at our monitored episodes, we can also learn a lot of information about this device. So the first thing that we can learn is that we have a VT zone programmed at 130 to 167 beats per minute. No episodes met criteria to fall into that zone, but we did have 124 non-sustained VT episodes. What's also very helpful on this screen is that it lets us know how this is programmed. The device is classifying non-sustained VT as more than four beats at more than 167 beats per minute. Very, very, very helpful information. And then underneath here, we have an example of one of these non-sustained VT episodes. So let's orient ourselves here. So we have a scatter plot over to the left with our intervals in milliseconds. The A intervals are the clear squares and the V intervals are the filled in diamonds. To the right of that, we actually have our EGM with our A tip to A ring on the top, and then our LV3 to LV4 on the bottom, which is a very interesting ventricular episode configuration to have set up. But it's what we have, and it's good. And then below that, you have your marker channels. So this is what the device is seeing. So the device is saying, these are my atrial events on the top of the line. The ventricular events are on the bottom of the line. The thinner lines that are straight up are sensed events. And then the heavier shaded lines are our paced events. So that lets us know where we are and what we're looking at here. These scatter plots are incredibly helpful when evaluating arrhythmias. What we can see, if you see on the left-hand side of that scatter plot, we've got our intervals. So 200 milliseconds, 400, 600, 900, 1,200. Remember that the lower the number of milliseconds, the faster the ventricular rate. And so as we look at this scatter plot, we can also see, if you look below that 400 millisecond, there's a line there. And so that's our VT zone. That's where it's saying, OK, I'm supposed to pay attention right here to tell you if I see anything or not. And what I notice, first of all, on this is that we have lots and lots of intervals, those V sense events, that are hovering right around that zone. They're so close to it. We also notice that this event went for a fairly long time. So while the device said this episode terminated and that the episode occurred in that blue box that's on the scatter plot, if we look backwards, we can actually see that they're having lots and lots and lots of ventricular events that don't match up to atrial events even before that. So for this patient, I would consider asking my physician, do you want to lower their VT zone so that we make sure we capture any of these events that occur because it looks like their VT is hovering right around their detection rate? Here's another example. So this is another Medtronic device. We have our scatter plot over to the left. We also have the EGMs to the right. So again, we've got our A tip to our A ring, LV3 to LV4. And we've got our atrial marker channels. And then we also have our ventricular marker channels underneath. I also put their histograms in here because this is really helpful as we look at these things. So what we can see is that they have known atrial fibrillation. We know that because of the number of bends greater than 220 beats a minute on that atrial histogram. We also know that they ventricularly pace almost all of the time. And we also know that this is a CRT device for two reasons. One, we have our LV3 to LV4 electrograms, so it has to be an LV lead there. But also anytime that you see effective V pacing, that's gonna be an indication that the patient has a CRT device. And Medtronic has an algorithm that will tell you a CRT pacing effective or not effective. Again, outside the scope of this module, but worth looking into with your local Medtronic rep. So what's this rhythm? So the atrial rate we can see is very regular, very fast. So I would call this an atrial flutter. We can also see the ventricular rate is fairly fast. This is a little bit difficult because there's more deflections on that LV3 to LV4 EGM than that are seen on the marker channel. I don't want you to think the device is wrong, it's not. But because this is an LV electrogram, depending on where that lead is in the left ventricle, you may also be picking up atrial signals on this lead. Does that make sense? So if you think about our heart and how it positions, the LV lead goes out through the coronary sinus and sits on the outside of the heart. It oftentimes is very, very, very close to the left atrium. And so this LV electrogram is actually picking up those flutter waves. But what we can see is our V pacing is occurring underneath on those marker channels. And we know that that's true because our histograms are really pretty appropriate. And also the fact that we have effective V pacing. So I hope that's helpful to think through. This is a very interesting one, one that I would not expect you to see very often, but I wanted you to keep this one in mind. If you're looking at LV electrograms, you may be picking up more than just ventricular activity on those electrograms. The marker channel is always gonna be your right ventricular marker channel. So Medtronic devices do not sense off the LV lead, they only sense off the RV lead. So that's where those marker channels are coming from. Okay, let's look at another one. So this is a patient observations, there's seven of them. So two shocks for VTVF, no failed. So bad they had shocks, good they were successful. One shock delivered for episode 561, another therapy failed. Two treated episodes longer than 30 seconds, that's important to know. One monitored VT episode longest was 34 seconds. And then they've got some long V sensing episodes. On our cardiac compass, we can also see where these episode occurred. Important to know here, the eyes at the top mean that that's when the patient's device was interrogated. The eye with a line underneath it, those are remote interrogations. And then you get these hash marks for whenever the patient had episodes. So we can see that recently they've had these ventricular episodes, but before that they had more AFib episodes. We can also see their activity levels been fairly stable over the last several months. So this is that same patient, and this is one of the electrograms. And I wanted to walk through this one with you as well. So again, we have our scatter plot here, again, very helpful. If you look right above that 400 millisecond line, that's gonna be our VT interval. Below that is our 300 millisecond line, and that's gonna be our VF interval. We've got our A tip to A ring at the top, our candor V coil as our second electrogram. And then we have our marker channels. So our atrial marker channels, ventricular marker channels. First thing off the bat, we can see that there's more Vs than As. The only rhythm where there's more Vs than As is ventricular tachycardia. That's 100% of the time. That's the only thing it can be. So that's good to know. As we look at our scatter plot, we can see that at the beginning here, the atrial events and the ventricular events line up. So again, our atrial events are our clear squares. Our ventricular events are our filled in diamonds. So we've got one-to-one all the way to the beginning there. Then you can see they separate. And it's a very, very sudden separation. So we have more Vs than As. This, again, the scatter plots are a little bit backwards. Faster rates are towards the bottom. Slower rates are toward the top. And then the scatter plots are very, very, very helpful because it will tell us what the device did. So it said, okay, we detected the episode. We declared that the patient was in BT. We delivered burst ATP to try to terminate it. And if you look at this, it failed. So the patient was still in BT. The patient got another burst of ATP. And then the device actually called this episode terminated, which is very interesting. Because if we look at the EGM at the bottom, this last square here, we can see we still have more Vs than As. But what you'll notice is that the BT rate slowed just a little bit, just enough that the device said, okay, I'm not in BT anymore, but the patient really was still in BT. So again, a really good example of why it's important to make sure you're looking at the EGMs, understand what the device is seeing, understand what the device is telling you it's seeing, and then verify that it's true. And so for this patient, this would be another really good example where you might wanna go to your physician and say, do you wanna lower their BT zone so we make sure that we capture any BT that's occurring, even if it's hovering right around that rate as this one did. On those observations, you also notice that it had those V sensing episodes greater than 60 seconds. My guess is those episodes are also these VTs hovering right around that BT zone, but you would be able to go look at those and evaluate that. Okay, let's do another one. So this is an Abbott device. The alerts here are the same as observations, that's just what Abbott calls it. So we've got our ventricular noise reversions, 15 high ventricular rate episodes were recorded. It's also telling us that our V safety margin is less than two to one, very important to know. So it's saying our safety margin right now is 1.8 to one. So things to keep in mind as you're seeing this patient in the office, a noise reversion means that the device is doing something that it considers non-physiologic. So it's saying, I see these episodes, I don't think that they're from a cardiac event because they're too fast, they're too irregular. There's a lot of things that classify things as noise. So the device says, when that happens, I'm gonna shut my eyes to that noise. I'm going to pace because I don't want the patient to have any lack of pacing, but I'm not gonna pay attention to that noise and use it in any of my algorithms to determine if I should pace or not, at least while that noise is going on. The safety margin is also important because this could be an indication that we've got something going on with this lead. If we have noise reversions and our sensing's a little bit off, this warrants very, very, very close evaluation of this lead while you have the patient in the office. A few things that you can do if you see a patient has noise reversions, you want to evaluate are they programmed unipolar or a bipolar for their sensing? You also want to do isometric exercises to see if you can replicate them. So those are things like having the patients push their palms together like they're praying or having patients grip their fingers like this and pull them apart and see if you can get noise or having patients cross their arm across their chest and see if you can replicate that noise. If you can replicate the noise, it's good because then we know where it's coming from and then we can maybe program around it. And the other important thing to note for this patient is that they only be paced 3.9% of the time. So they rarely need pacing support. So noise reversions in a patient who paces pretty infrequently are not necessarily as urgent as noise reversions in a patient who is pacemaker dependent. And I'm sure that makes sense to you. Here's another example. So this is a high ventricular rate event. What we can see here are both the histograms and then also our electrograms. So let's start with our histograms. Again, Abbott device, the shaded in boxes are gonna be our paced events. The clear boxes are our sensed events. Remember those clear circles are where the device says the patient's rate should be based off of the sensor that's located within the device. This patient also has hysteresis programmed on. I don't talk about this in programming, so we'll just mention it here. Sometimes you want for a patient to have intrinsic conduction as much as they can. So for example, a patient might be programmed with a base rate of 60, but every once in a while, they go into the 50s and they do really okay with that, but you don't wanna leave them at a base rate of 50 all the time. So what you can do is program them with a base rate of 60, but then have hysteresis turned on to 50, which would say, okay, every once in a while, I want this pacemaker to look to see, does the patient have a heart rate in the 50s? And if it does, we're gonna let the patient's intrinsic heart rate come through, but if it doesn't, we're gonna keep our base rate a little bit higher. So it's just a way to encourage intrinsic conduction for your patients where that might be appropriate. I would say that's one of the lesser used features on devices. Another one that's very similar to that is a sleep feature where you can program when the patient is sleeping and decrease their rate then. Again, I don't really talk about that in the programming section, but they are two features to be aware of. And I wanted to bring it up since it was on this histogram. So as we look at this electrogram, what we can see is our V sense at the top. We can also see our markers and then our intervals again in milliseconds. And I wanna give you just a second to look here and you can't tell me, I wish you could, what you think this rhythm is. Recognizing that we don't have an atrial EGM, the things that we know are that it's a V-sensed event, it's an irregular rhythm, and the rate is fairly fast. So that's also reflected in the histograms where we see rates frequently 80, 90s, 100s, a few 110s. So I would say this is probably atrial fibrillation with an okay rate response. Depending on what the patient was doing at this time, you might wanna reevaluate their rate control strategy. Okay, let's talk about atrial fibrillation. So this is an example of a trend of atrial fibrillation. You're gonna get these on every single device that has an atrial lead. This is an Abbott device. You can see that we have months back in time and then this is our AFib burden over time. This is why trends are very, very helpful because you might see a total AFib burden of 4.9% and say, oh, that's okay. But we look at this trend and what we can see is that they very recently have gone into atrial fibrillation and appear to be still there. And so this warrants further evaluation because we want to make sure that if a patient has a change in their atrial fibrillation that we're addressing that appropriately. And so as we think about AFib episodes, there's a few things that we need to keep in the back of our mind. One is our AFib classification. There are really, really, really good AFib guidelines. I would encourage you to go read and evaluate for yourself. The Heart Rhythm Society has them. They're done in conjunction with the American College of Cardiology. But paroxysmal atrial fibrillation are episodes that last less than seven days. Persistent atrial fibrillation are episodes that last more than seven days. Longstanding persistent AFib are episodes that have gone on for maybe weeks or a month. They're not just these seven or 10 day episodes, but maybe the patient's been in AFib for three or four or five months. That would be a longstanding persistent AFib. And then permanent atrial fibrillation changed its definition at the most recent guideline. And what permanent atrial fibrillation means now is that either, yes, the patient is in permanent atrial fibrillation, or we have abandoned plans for rhythm control. So if the patient says, you know, I feel fine in AFib, I don't really have any symptoms. The physician says there's no really medical need for us to try to keep you in sinus rhythm, then that can also be permanent atrial fibrillation. So you can have permanent atrial fibrillation with a very short episode duration of atrial fibrillation if there are no plans for rhythm control. The other thing to think about when we think about our atrial fibrillation in our patients is should they be on anticoagulation or not? Oftentimes that's not the device clinician's decision, but we do play a really important role in helping our physician partners evaluate these episodes and bringing to their attention if a patient has episodes that they may want to treat. So recommendations for anticoagulation are based on the CHADS-2-VASc score. I'm not going to go into that here because again, it's located in the guidelines. Duration of AFib episodes is important whenever you're thinking about should a patient be on anticoagulation or not. And then there's most recently been a lot of data around subclinical atrial fibrillation. So these episodes that we find of AFib on a patient's device should we anticoagulate them or not? Because they are asymptomatic and they're subclinical, meaning the patient might not have found them. There's a lot more research to come there, but this will be an important space to watch as we move forward. So here's a really good example of a cardiac compass for a patient that has atrial fibrillation. So first of all, how would you classify this atrial fibrillation? Recognizing the hash marks at the top here are months. So we've got March, April, and May showing. So we have at least more than seven days of atrial fibrillation. So I would call this persistent AFib. We can also evaluate our ventricular rate during AFib. This though can be a little bit deceiving because what these devices do is it's gonna tell you your average, but then the hash mark up also gives you your max. And your max could be just one interval. And so it's a little bit difficult to base strategies just off of this graph. The histograms are actually much more helpful when you're looking at V-rate during AFib. But what I would say here is that the patient's V-rate during this persistent AFib episode is probably a little bit elevated. We probably could use a little bit more help with rate control. And the most important clue here is this average V-rate day and night, because that's not the max episode. That really is their average V-rate. And we can see that oftentimes here we're hovering right around 90 to 100 beats per minute. The other things to look at whenever we look at observations are any other diagnostics that the device gives us. So AFib burden over time, what does that trend line look like? Are they having intermittent episodes? Were they in sinus and now they're all of a sudden in persistent atrial fibrillation? Are there clues there that might tell us how the patient's feeling in atrial fibrillation? You can see their activity level and does that correlate to their AFib episodes? Oftentimes patients will have AFib episodes, their activity level drops because they just feel poorly and their heart failure diagnostics might elevate because they're also accumulating fluid. The ventricular episode frequency we touched on briefly, that's gonna be mostly with your CRT devices. And those are episodes where CRT pacing was not delivered. So V-sensed events were occurring, but not fast enough to meet any VT threshold. And then our percent pacing trends, which we were able to see on that last example, where you can evaluate over time, not only heart rate, but how much the patient is pacing in both the A and the V over time. All of those things are really, really important clues as we look at device programming and as we talk with our patients and evaluate how they're feeling as we're interrogating their device. So I'm gonna stop here with the interrogation module because the last part of our PBL stop is programming and we're gonna deep dive into that in our next module.

interrogation techniques

pacemakers

defibrillators

battery status

lead impedance

thresholds

arrhythmia episodes

device replacement

battery statuses