MRI, CIED and Lead Management

Podcast Transcript

Announcer:

Welcome to Cleveland Clinic Cardiac Consult, brought to you by the Sydell and Arnold Miller Family, Heart, Vascular and Thoracic Institute at Cleveland Clinic.

Thomas Callahan, MD:

Hello, and welcome to the podcast where we talk about all things related to lead management. I'm Tom Callahan, and I'm joined by Dr. Bruce Wilkoff and Dr. Debbie Kwon, the Director of Cardiac MRI at Cleveland Clinic, and really one of the leaders in cardiac MRI. Welcome to both of you.

Deborah Kwon, MD:

Thank you so much. It's an honor to be part of this.

Bruce Wilkoff, MD:

We're really glad to have you here, Debbie, you've done so much with MRIs here and it's been so much fun collaborating with you, we thought we should tell a little bit of that story.

Deborah Kwon, MD:

Yeah, sure. I think my area of cardiac MRI just really started as a passion when I was as a fellow here at the Cleveland Clinic. And I remember seeing my very first cardiac MRI and I was like, "Oh my gosh, this is amazing. I can't believe you can see the heart with this much detail," and particularly scar. I was just so fascinated that you could see it so pristinely. And my research actually started off in hypertrophic cardiomyopathy. And I was giving my talk on that in a research conference, and I remember Pat Tchou raised his hand and said, "Oh, that's really interesting. Have you ever thought about, or does anybody know what kind of impact cardiac MRI can have in terms of predicting VT in patients with scars?" And I was like, "Oh my gosh, that's an amazing question." And that just launched my whole area of research that I am now currently doing today. And obviously a lot of people who have scars and potential VT also have devices. So that's also been an area that has been a real challenge for us, and something that's very exciting too because there's been a lot of movement recently in terms of image optimization and techniques to really help improve the image quality, which I think is really important because these patients are the most at risk and the most vulnerable. So, it's really our need to really address this population.

Thomas Callahan, MD:

Well, a quick nod to Pat Tchou, who we lost, such a brilliant mind. And you mentioned how he touched your career and he's touched really so many of us through his brilliant career. So, a nod to him.

Moving on through with the cardiac MRI, you and I actually did a fellowship, we kind of followed each other through training and did our training around a similar time. And so, in some ways I've been maybe your nemesis throughout training, so putting in these devices, which for a long time would cause problems with cardiac MRI. And so that's a little bit of a backstory too, the whole story of how we got to a place where we can actually comfortably get MRIs for patients with implantable devices.

Deborah Kwon, MD:

Yes, yes. That's also evolved quite a bit here at the Cleveland Clinic. We used to have such a barrier to patients with devices, where in the cardiac MRI area we would not touch patients with a 10-foot pole if they had a device, regardless of if it was conditional or non-conditional. There was just a real fear. We really have to thank Bruce Wilkoff for really pioneering that. His work is really the only reason why we even started to have any openness to doing them here. And now we're doing one or two a day, it's really become routine practice.

And so yeah, there's been a lot of things that we've learned along the way. And one simple thing, I remember talking to Roy Chung because he sent us a patient and we scanned them, was safe, but there was so much artifact. The device was like right on top, the heart was right underneath it. And I had asked him, "Is there any way that you could try to put the device higher up on the shoulder?" He is like, "Oh, we always do that, but over time the device just kind of sags." So, what we started to do routinely now, which has made a big difference, I mean, it's something very practical, it's nothing fancy, but just to lift the arm up and put the arm over their head when they go into the scanner. And that's actually allowed us to use our typical sequences in a subset of patients where it just really lifts it up two- or three-inches superior to where the cardiac borders are. So that's made a big difference for us. Unfortunately, patients who are older have arthritis on their shoulders, and so sometimes they just physically can't lift their arm above their head for 30 minutes. So, there's still challenges we have from that aspect, but very, very practical things that don't really take high-tech interventions can also be done.

Thomas Callahan, MD:

That's a great tip.

Bruce Wilkoff, MD:

Debbie, you were talking about one or two a day, but you're talking about cardiac MRIs one or two a day?

Deborah Kwon, MD:

Yes.

Bruce Wilkoff, MD:

But that's beyond all of the head stuff.

Deborah Kwon, MD:

Yeah.

Bruce Wilkoff, MD:

We started off with head MRIs and shoulder MRIs, and hip MRIs, and knee MRIs and such like that, but this is just cardiac MRIs. So, we've really shifted our focus tremendously that way.

Deborah Kwon, MD:

Yeah, yeah. We actually have a dedicated slot, one dedicated slot a day, for devices, because we know that there is this need. So, we have a slotted schedule so that we know that a nurse will definitely be available for that particular time. Now sometimes there's urgent cases that need to be added on in addition to that, and so sometimes we are able to accommodate that, but that just shows how much things have evolved and that we have a dedicated slot scheduled now just for a patient with a device.

Thomas Callahan, MD:

That's fantastic. Debbie, along the same lines, you talk about tricks that you can use to try and get better images. Is there something that you see with some frequency that you say, "I wish they hadn't done that," or "I wish they would do it some way differently," from a device either lead or implant tactic. Maybe making sure the device is a little bit higher. Anything else, like types of leads or lead position?

Deborah Kwon, MD:

That's a really good question. I think the biggest issue with the artifacts is the generator. It's not really the leads. The leads cause a little bit of artifact, but it's very because they're so thin, the amount of artifact that it results in, it's very local, whereas the generator causes this big susceptibility artifact that spans, could be several centimeters beyond the generator itself. So, I think I'll just put it up as high as possible. And ways to anchor it there so it doesn't sag over time, because obviously it can be in a perfect place when the patient's lying flat, but then we spend most of our time upright and so gravity pulls it down. So, I don't know if there's mechanical ways to allow it to stay in place.

But we actually right now have been looking into building a database of cardiac MRI patients who had devices so that we can specifically look at that. Are there certain models or configurations that result in more artifacts than others? Because we recognize, now that we have Dr. Pasquale Santangeli here doing VT ablation, we're going to get a lot more of these patients, and it's really vital for us to understand how we can better optimize these images. And so, one of the things we want to know is predictors, because then what can we do then to address those specific predictors?

But we've done a lot actually, I'd say that before 2018, 2019, probably our image quality would be as bad as 40 to 50 percent likelihood of having adequate image quality. But we've done a lot of work to really try to optimize our sequences so that we can improve that number. And so, for cine imaging, we typically use a sequence called SSFP, and that is very sensitive to these susceptibility artifacts. So, we've switched to something called gradient echo, and that's made a big difference. And then recently, since Chris Nguyen came, our biomedical engineer, he's also made an amazing impact on this. We've also really addressed the bandwidth for these sequences, and that's also made a big difference.

And then in terms of scar imaging, we incorporated something called wideband, and that's also helped to specifically address the artifact that we see on the scar images, the late gadolinium enhancement images. And so, the incorporation of that plus arm raising, I think our image quality can be as good as if they didn't have a device. But obviously if we can't raise their arm, I'd say it's probably up to 80% likely that we can get a good image quality.

What we typically do is, or I've told the fellows in the MRI tech, is to look at the chest x-ray. And if they can't lift their arm, the chest x-ray and how close the device is to the heart border will give us a good understanding of the likeliness of our being able to get good quality images. However, if they can raise their arm, then obviously that is a different ballgame, that is going to be much more likely that we can get good images.

Bruce Wilkoff, MD:

Debbie, a lot of the time the skin is kind of lax. Do you tape it up?

Deborah Kwon, MD:

Yeah, so that's what we're trying to develop now that Chris is here, to use his engineering skills to see if there's some kind of, can we use tape or can we use something else to move the device up. The issue with the tape is that a lot of the times the device is not so prominently bulging from the skin, so sometimes there's not anything that we can actually anchor with tape to pull it up. If it's underneath the muscle or something like that, it's hard for us to really have something to grab onto.

Bruce Wilkoff, MD:

When we first started doing MRIs, you're right, there was a lot of, I would say, fear and risk avoidance, and it was hard to even start a conversation. This goes all the way back to the '90s. But it's become more comfortable. Still, there's a problem of barrier, not every site is doing MRIs with patients with pacemaker because it just takes more effort. I mean, this is a big investment that you all make.

These types of optimizations that you're talking about, how well established is this in the MRI community outside of the Cleveland Clinic? I mean, there are some sites, but how well established is this in the MRI community at this point?

Deborah Kwon, MD:

That's a really good question. I think it's a lot of variability, and it all depends on how often they're getting their referrals. Because if they have a big EP referral, then it's worth that investment, as opposed to just sporadically happening. So, I've kind of noticed that the places that are doing this really well are the places that have a big EP presence and a real interest for getting cardiac MRI on their patients. But I'd say it's pretty variable. The one thing though is that once you have an optimized protocol, it's pretty standard. I mean, obviously there's going to be patients that are more difficult, and you have to have really dedicated onsite expertise to be able to navigate that and troubleshoot it on the fly. But in terms of having a ready-made package protocol, it's not that hard, you just have to have the right people to know to ask or to get consultation with. And then once that's established on the scanner, it's usually just run it and go, and there's usually a pretty good result from that.

Bruce Wilkoff, MD:

Is it published? Is there a resource that you point people to that talks about this?

Deborah Kwon, MD:

There are some articles out there. I think the issue is that sometimes it's scanner dependent, where you find those parameters on the scanner can sometimes be difficult. So even though you know what kind of sequence you want, sometimes you might not know how to adjust those parameters on the user interface because you get in there, and sometimes you need to have the support people come in and change those parameters for you. Depending on the site. There are some people who are just very savvy with it and know how to find those parameters. That's why it's very helpful if they have an onsite MR physicist or a vendor scientist that can help them with that. But again, once those parameters are set, then usually they don't change.

Thomas Callahan, MD:

That's great. Debbie, how about some of the newer device technologies like leadless pacemakers, subcutaneous ICDs? Do they present any unique challenges?

Deborah Kwon, MD:

Yeah. I think the subcutaneous ICDs are often more challenging because they're bigger and they're usually closer to the heart. So those are harder, actually they cause a lot more artifacts. But sometimes if their chest wall is far enough away from the heart border, we can see it well. But yeah, subcutaneous ICDs unfortunately cause a lot more artifacts than the typical ICDs. The leadless, they're small, so they cause the local artifact. I think the issue is that if that area where it's located is the area where there's a question of scarring, in that local area we won't be able to see much.

Thomas Callahan, MD:

Sure. I mean, one challenge that seems to come up with some frequency is a relatively young patient who has some AV conduction disease gets a pacemaker, and then maybe a few months down the road or even longer, there's some question about, well, is this sarcoid? There's something else that's happening that makes us worry about sarcoid. And often part of that workup is a cardiac MRI looking for patterns that suggest sarcoid. In my practice I try and think about that, I try and have a low threshold to think about sarcoid and try and test for it. How challenging is that for you when you have a patient coming to the scanner, already has a pacemaker, with a question of is this cardiac sarcoid, and any other ideas or thoughts you have around that issue?

Deborah Kwon, MD:

Yeah, so actually pacemakers don't cause that many artifacts. The generators, I guess the coiling inside of there is a lot different than ICD. So, the local artifact that pacemakers cause is much less than ICDs. And CRTs are the worst, obviously. I think for pacemakers it doesn't usually cause that big of an issue in terms of the susceptibility artifact. Now, if the patient is having a lot of PVCs, or unpredictably irregular heart rates, that causes a different kind of challenge, that's not related to the pacemaker necessarily. It just is that if they're regularly paced throughout the exam, that's easier for us because then we can gate better. But when the pacemaker is turned off, or sometimes we've noticed that when the device parameters are changed, then they start having a lot more PVCs or there's other arrhythmias that occur, and that becomes a challenge for the cine imaging and gating and whatnot. So that's not necessarily the pacemaker itself.

But what I would suggest for a lot of these patients is to consider getting an MRI right before you put the device in it, because at least that's going to be your best shot to get the best kind of imaging. And it's also going to be a good potential baseline for if something evolves over time that you can then compare to that.

Thomas Callahan, MD:

That's great.

Bruce Wilkoff, MD:

Yeah. I was wondering, at one point, matter of fact currently, the indications were in order to get an MRI, you had to have an MRI conditional device. So, it was an indication for lead extraction to allow people that having abandoned leads still is somewhat of an impediment. You said that leads were not really a problem, but what happens if you have four, five, six leads inside, does the volume of leads make a difference on the quality of the information that you're getting?

Deborah Kwon, MD:

That's a really good question. I personally haven't seen patients come through with, because that's one of the contraindications is abandoned leads. We really push back a lot on that, but I would, theoretically it should cause, I mean, it should be probably additive. So, if you have a bunch running together at the same time, the local artifact around that tunnel of a bunch of leads running together is probably going to be more than if there's just one. Those leads usually go through the tricuspid valve and then insert into the RV. So as long as it's far away enough from the myocardium itself, if the artifact is mostly in the blood pool, then it doesn't really impact things too much.

Bruce Wilkoff, MD:

Okay. Yes. Well, we have been a little bit on the conservative side. We've been moving more and more as we've developed comfort with this, but we still have held on to the capped, broken and epicardial leads as being a contraindication. Although, when the indication gets strong enough, which is great working with you as a cardiologist as well as a radiology expert, cardiologists tend to have an understanding of risk benefit, and we've been able to work together as a general thing. The risk benefit doesn't really play a role there as much. So, we have tried to go there, but we're still lagging back on that one point.

Deborah Kwon, MD:

Yeah, yeah. I think as we get more data and experience too, I mean, that's kind of how all of this evolved, is after we had done several, then we look back and say, "Oh, there was never an event. It probably is going to be okay."

Bruce Wilkoff, MD:

Right. And again, with that risk benefit in mind, it is clear that the benefit has been far greater.

Deborah Kwon, MD:

Yes.

Bruce Wilkoff, MD:

And we've had no serious events ever with, So that's important.

Deborah Kwon, MD:

Right, right.

Thomas Callahan, MD:

Well, Debbie, you've had such an impact here and in the MRI community at large, and really helping advance the field and push what we can do, especially with patients with cardiac implantable devices. So, thanks for all the hard work you do and thank you so much for spending time with us.

Deborah Kwon, MD:

Oh, yeah. Thank you so much. It's been so much fun. And I always like challenges, so thank you for always sending us challenging cases. Pushes us to really know our craft and learn more.

Thomas Callahan, MD:

Excellent. Well, until next time, thanks again.

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