Dr. Rebecca Kumar joins Sara to provide overview of ventricular assist device infections!

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Hello, everyone.

Welcome to Febrile, a cultured podcast about all things infectious disease.

We use consult questions to dive into ID clinical reasoning, diagnostics and anti-microbial management.

I am your host, Sara Dong, a Med-Peds ID fellow.

Here on Febrile, we use patient cases and chat with ID consultants to learn about high yield ID topics.

I am very excited to introduce our guest today, Dr.

Rebecca Kumar.

She is a physician and assistant professor at MedStar Georgetown University Hospital and the Division of Infectious Diseases and Tropical Medicine.

She previously completed her internal medicine residency at MedStar Georgetown in Washington, DC followed by her fellowship in infectious diseases at Northwestern University in Chicago.

Welcome to Febrile, Rebecca!

Thanks so much for coming.

Thank you so much for having me.

I'm super excited to be here!

I am still, before we jump into the case, going to ask as everyone's favorite culture podcast, we would love to hear about a little piece of culture that brings you joy or happiness.

Yeah, of course.

So I really love music and enjoy listening to my Spotify account all the time.

A band that I'm super into right now is Pinkshift, and then another one that I'm really into is Sorry, Mom.

They're both kind of like riot girls / pop-punk bands that are great to just like jam out to, well, you know, chart reviewing or writing notes or like, you know, actually doing fun stuff.

And once, once, um, you know, things are lifted, I really hope that I'm able to see both of them live.

Yeah.

It'll be nice to go to concerts again.

I agree.

One day, well today's consult question is assistance and workup of fever and purulent drainage from a drive-line exit site of a VAD.

Ooh, we're doing something a little different.

We're going to talk about VAD infections.

Today is not necessarily a diagnostic mystery.

Um, but before we jump into the case, I thought we could do a quick introduction, talk quickly about VADs.

So these are implantable ventricular assist devices.

Because I know we have listeners that may not have cared for patients with a VAD before, and it would help to have a little bit of orientation.

So, a VAD is a mechanical pump that provides circulatory support by augmenting the ability of a failing heart to deliver blood flow.

So in patients with refractory heart failure, this can help with improving survival, functional status, quality of life, and they can be implanted in the right or left ventricle, but vast majority are going to be left.

So people may hear the term LVADs.

And so these are continuous flow pumps, pretty much all of them for the most part now.

And so I've put some names of devices that you may hear, which are Heartmate II, Heartmate III, HVAD, and JarvikHeart.

Those are just ones that we hear of, and you'll probably hear the same ones at whatever institution you're at.

Um, and so the pumps are these centrifugal pumps that.

It's almost, I, this is how it's described to me that it's like a rotor floating between two magnets.

So there's not really friction.

And they last longer and have less hemolysis than the earlier pulsatile pumps, which had more sort of thrombotic complications.

And the VAD can use different speeds to mimic increases or decreases in flow.

And the nice thing about the newer ones as they're also smaller and implanted directly into the pericardium and so we'll talk about the structure of the VADs, but previously there were these preperitoneal pump pockets.

So if people look up pictures, you'll see the difference there.

And the newer ones have improved small caliber drive lines that are more durable.

And so we're going to put some pictures in the Consult Notes for this episode on the website, but you can also easily find these on the internet, but Rebecca, can you mention some of these sort of key components of the VAD for an ID person to know?

Yeah, of course I'd love to.

So essentially there is the inflow cannula which is the part that connects the pump itself to the heart and allows blood to flow into the pump.

From the pump, then you have a outflow cannula which then, um, sort of exits through and pumps the blood out to the rest of the body.

Attached to the pump itself is a, is the drive line.

And so that drive line ends up snaking through the chest, into the abdomen and exiting at the lower part of the abdomen and ends up connecting to a controller set, which is where the cardiologists will then adjust the amount of blood flow that occurs, et cetera.

And this is the component that will alarm if there is detection of like outflow obstruction or anything else like that.

And from the controller, you then have the cords leading to the battery pack, which is also external.

The drive line itself just of note has sort of a piece of velour which sort of attached to it near the exit site.

And this usually should sit inside of the like, uh, like peritoneal space not be exposed.

And that exists because of the fact that it helps with granulation tissue formation, and really just helps, um, create sort of like a nice seal around the drive line and the patient's skin.

One of the big issues though, is that if it ever gets pulled out or exposed a little bit, it's a great place for bacteria to sort of commense and live on because it's providing the bacteria huge area, surface area to survive off of.

And the last thing that I was going to mention before we jump into the case was sort of, what do we know about how these patients do.

More of a bird's eye view.

And so there are some large databases or, people may find INTERMACS or Interagency Registry for Mechanically Assisted Circulatory Support database, but basically they're over 4,000 cases of LVADs that have been followed in this database, but I think there's over 20,000 patients in the actual registry.

And so they put out these annual reports that tell us a little bit about how these patients are doing.

And so survival with the VAD is now about 80% at one year, somewhere alittle over 70% at two years, and then 35% at five years.

And the average time that patients live with device support has changed from about 120 days to almost a year now.

And so I think the other very helpful thing for us to think about is almost half of patients who receive VADs are considered destination therapy.

And about 57% are VADs that are placed in those who are listed or under evaluation for heart transplant.

And so people will hear the term bridge to transplant.

So I think it's important to know the difference between that for patients who are actively moving towards transplant versus destination therapy, just to provide them support.

And then about 40% of heart transplant recipients have been supported with the LVAD prior to their transplant.

And so for us, in ID, infection is one of the most common complications of VADs and does contribute to mortality on the transplant wait list.

But I have to also say that many patients, even those with infections, get transplanted and have excellent outcomes.

And so we just really wanted to talk about VAD infections today, how to approach them and think about them.

Um, anything I missed Rebecca before we jump in?

No, you did an amazing job.

Um, all right.

So Rebecca today we have a 70 year old male.

He has a history of coronary artery disease, had a CABG in the past, and has ischemic heart failure with reduced EF with a left ventricular ejection fraction of 15-20%.

He had a HeartMate II LVAD placed in 2017 as destination therapy.

And he came in today with fever as well as pain and purulence from his drive-line site for about 2 days..

He has not had chills, chest pain, GI symptoms, rash..

He says he hasn't had any issues with VAD alarms, or recent trauma to the drive-line that he can remember.

He had a fever to 101.8 Fahrenheit in the emergency department, but otherwise is stable.

I will just mention for his post VAD implant course, he has had some recurrent GI bleeding with AVMs or angioectasias is that were thought to be related to the VAD, which is a complication that is seen.

He's had one prior episode of erythema, tenderness, and purulent drainage from his driveline exit site about a year after his LVAD was placed.

So several years ago from now.

at the time he had a surface wound culture that had no polys, but heavy growth of MSSA.

And he completed several week course of cephalexin and then stopped antibiotics.

And so today on exam, there is an LVAD hum, his lungs are clear.

His abdominal drive-line exit site had some yellow / purulent drainage on the gauze.

And he's complaining of pain at sort of the two o'clock position like if you're looking at his tube and I will mention here, I don't know if this is different other centers, but at least for us many places prefer that there are specific nurse practitioners or physicians who remove the drive-line dressing.

So if you don't know, it's always good to ask the VAD or transplant team just to make sure.

Because you certainly don't want to expose the wound of someone if perhaps just changed the dressing.

Exactly.

And the other thing you can do also is just ask the team if they took a picture, that's another way to like, get a look at.

It's just been dressed or something else, you know?

Yeah.

I feel like these patients are followed so closely in clinic.

That's really nice.

They tend to have great pictures or images when symptoms are developing.

They definitely do.

And we as ID, one of the things that we can do to help out is take the serial photos as well if you're trained in taking care of the driveline.

Yeah, so we do have some labs.

He had a white count of 16,000 with a diff having 85% neutrophils.

He does have some baseline CKD.

His current creatinine is 2, up from a baseline of 1.4.

He has blood cultures that are sent and pending.

Their primary team has also sent a swab of his drive-line exit site.

And they've gotten initial ultrasound, which showed no clear evidence of abscess in the superficial soft tissues near the exit site.

And so now we have the general story, but I'm going to take a step back and ask.

Where do we even start when thinking about VAD infections and can you walk us through the definition of infection?

Because I think that really informs how we make our plan.

Yeah, that totally makes sense.

So essentially we can divide our patients who have VADs.

We can divide their infections into three sort of categories, three broad categories, you have VAD specific infections.

So those are infections related to the VAD itself.

We can define them further as a pump or a cannula infection.

So that essentially means that the mechanical, like the pump itself or the inflow cannula or the outflow cannula, there is an infection somewhere within that system.

You can also have a pocket infection.

This was sort of a bigger issue back when the pumps used to site like in the preperitoneal space, but now, um, since they're closer to the heart, um, and much smaller, this comes up less as an issue.

Um, and then finally the most common type of infection, which I believe you mentioned earlier, which is a drive-line exit site infection, and those are further categorized into either superficial infections (so really just involving the exit site itself), or a deeper infection (which can involve the musculature or just track along the drive line itself).

Then we have our VAD related infections, so these, the way that I like to think about it are they are infections that are complicated by the presence of a VAD.

So that would mean any sort of bloodstream infection, any sort of mediastinitis, any sort of endocarditis.

So infections that essentially you or me could get, but if we had a VAD, it would just be that much harder to take care of.

And then finally we have our non-VAD infections.

So that's like C diff or a UTI, anything along those lines that really just doesn't involve the VAD directly.

Great.

And so we had gotten some blood cultures and labs.

What is sort of your initial workup approach when you have at least this initial information gathered?

Do we need to think about imaging or other tools?

Yeah.

So if you look at the guidelines, they do recommend like a UA, they recommend a chest x-ray.

My personal practice preference would be to get the blood cultures, like you said, which are part of the guidelines and to get a CBC, which you had also mentioned and is part of the guidelines.

I actually will generally jump straight to CT scan, which may not be necessarily "choosing wisely".

But I do think that it gives you a degree of information that is helpful beyond just an x-ray.

Specifically, I look for fluid collections around, um, the drive line exit site.

You could also accomplish something similar with an ultrasound.

The other thing to consider getting as well as an echocardiogram as well.

But that's more just to look for evidence of vegetations, et cetera.

Yeah.

And so when we met our patient, you know, there was some concern for deeper infection because of the fevers and the white count.

And so while we're waiting on the imaging, he's been placed on empiric vanc, pip-tazo, but I want to see what you think about antibiotic selection and what organisms do we need to have at the top of our list for these VAD-specific infections?

So the organisms that I worry about the most are Staph aureus or any of the Staph species, um, particularly because a lot of these, so the most common type of VAD infection will be the driveline exit site infection.

So you worry about skin flora, things like that causing an infection.

So that's why Staph is important to cover for.

For this patient, in particular, you had mentioned that he had had a history of MSSA, which for this patient in particular, the MSSA is going to go to the top of my differential.

An additional concern is Pseudomonas and other gram negatives.

The pip-tazo is a reasonable option.

I think you could get away with cefepime because anaerobes aren't commonly drivers of these VAD infections.

I think one thing that is tough is we are usually getting these sort of like surface/skin micro swab.

I don't know how you have any like, tips for thinking about separating out what's skin versus really causing infection.

And I think the answer is that "it depends."

And I agree with that.

And I think part of it is also sort of getting a, an idea from the patient about how the area has looked, because, you know, in this case, this patient does have some drainage, but there are times when people can develop allergy to the chlorhexadine that we use, um, typically for cleaning the site and you can get skin breakdown.

There can be some inflammation and some erythema, and sort of getting the history of, you know, this is something new that's happened and they're noticing it has worsened and is associated with chlorhexadine.

You can then try giving them or try using iodine instead.

Well, the patient fortunately does not have another fever after the one in the emergency department.

And after starting antibiotics, says that the areas near his insertion, sorry, his exit site, for the most part resolved.

Our wound culture.

So the swab from the exit site did grow MSSA again.

And fortunately, his blood cultures are negative.

And so around this time he's transitioned from the vanc, pip-tazo to cefazolin.

We do get an echo that looks like it's at baseline for him.

And then there is a CT abdomen, pelvis that doesn't show any evidence of infection in the chest or unusual appearance of the LVAD, but he does have moderate subcutaneous soft tissue stranding along the right anterior abdominal wall (so the driveline insertion site) as well as into some of the underlying mesenteric fat.

And so there fortunately is no fluid collection or organization there, but there's definitely some stranding that extends.

And so you've walked us through the types of VAD specific infection.

And now I want us to get to thinking about antibiotic strategies and how it's different for these.

And so in this case, we decided to treat as sort of a deep drive line infection, but I think it's helpful to think about how things would be different if say his blood cultures were positive.

Right.

So if his blood cultures were positive, then you would sort of think you'd take a step back and think, is this a VAD related infection or is this a VAD infection?

Specifically, you would worry about a pump infection.

Um, You know, and depending on which of those you thought it was, the duration of antibiotics and your choice of IV versus PO would change.

So if I was worried that this was actually like a pump or a cannula infection, I would treat them for at least six weeks.

Um, probably longer to be honest, um, with IV therapy, if it was a bloodstream infection, you know, technically you could treat them for two weeks, but I think in clinical practice, you don't see that happen very often.

I think we get very worried about the VAD getting seeded.

Um, and that's partially because it's such a big deal if it does get seeded.

It can be very difficult to remove the VAD itself.

They always say that the bravest surgeons are the internal medicine or infectious disease doctors.

So it's easy for us to be like, yeah, like it's affected like "we need source control,", but like from a practical standpoint, it is very difficult to remove this piece of hardware that's attached to your heart.

Yeah.

And so how long do you think we should treat our patient?

Honestly, I would probably treat this gentleman for at least four weeks.

And then at that point I would do, and this is obviously not in the guidelines or anything else.

I would repeat the culture as well.

If it's still as positive with the same organism, I would probably then maybe extend out the IV duration.

There's also the fact that this, because this is a deeper infection, this gentleman's probably going to need oral suppressive therapy and generally, we end up keeping these patients because he's a destination VAD, or a destination therapy.

Um, this would be somebody who would likely be on this antibiotic lifelong.

We kind of had the same thought, had a superficial drive line infection in the past, now here with a deep drive line infection and the same organism.

Um, so made the plan to continue with oral suppression.

That kind of raises sort of one of the final questions that I had was.

How does a patient's future as destination therapy versus bridge to transplant impact how you manage their infection?

You know, does it, maybe it makes no difference, but I think it tends to be part of the conversation when we're figuring out treatment courses.

Right.

You know, it's hard because it's a big deal to have a ventricular assist device, even though it is providing these patients with a longer lifespan, better like presumably a better quality of life, because they're not as symptomatic, et cetera.

It's an additional burden to ask people to take additional IV antibiotics.

Like for example, I've taken care of patients who have had multi-drug resistant pseudomonas where an oral therapy is not an option and they're a destination VAD.

And so, um, this gentleman was on meropenem for about like nine months and was still growing out the pseudomonas from the driveline exit site.

I think this is a good opportunity to sort of at least discuss almost goals of care with these patients or at least bring up the topic, make sure that they know that what you're doing is mostly mitigation, and not necessarily curing or eradicating the infection.

You're trying to keep it under control.

And I think, I mean, I think that's kind of what I was thinking too, is I feel like we basically revisit that goals of care type discussion every time, because that's like, yes, if you did develop like an awful reaction to this, then we just sort of have a discussion about it and weigh risk benefits.

Right, and then the other thing is like, I have stopped therapy for destination VADs in the setting of like somebody wanting to take a trip somewhere, or, you know, like these things that I, we take for granted most of the time.

It's very different for somebody who has to take their refrigerated IV antibiotics with them everywhere.

Um, so it's a lot of like working with the patients, working with the cardiac surgeons or the cardiologists as well to come up with something that everybody kind of feels comfortable with, but that also allows the patient to live their life to some degree.

And so we'll, I'll, make/have a graphic for this sort of about the management.

Because you talked a little bit about antibiotics.

There's this IV course and then oral suppression in certain cases.

And then I think there's non antibiotic related strategies that we have to think about.

And you've touched on how, obviously we're not just saying, take out the VAD every time.

It's not the same as taking out like a central line.

Um, but I think there's other things sort of like wound care and skincare that probably are helpful for thinking about preventing future infections.

Is there anything that you counsel patients on?

Yeah, so, um, if I tell them that they noticed that there's like a lot of redness, if it's getting itchy, et cetera, to let us know.

Some of it's a little bit of trial and error in terms of trying out different, like, switching from the chlorhexadine to the iodine and seeing if that makes a difference in their symptoms.

Sometimes, we didn't touch on this, but a lot of times we'll give patients like a separate, almost like it's like a sticker with a hook.

And it's what we call the anchor.

And that sort of helps give an additional bit of slack to the patient because one of the things that can predispose patients to infections is having the driveline tugged upon, or sort of pulled out a little bit, and the anchor almost allows you to create a little bit of slack so that if there's any pulling of the controller or anything else, you have a little bit of extra space.

Um, so just checking to see if that's causing any skin irritation as well.

I think in terms of driveline exit site infections, those can also be very difficult to have surgical intervention upon, but if, if the, um, surgeons are willing to do so, and you think that it would help with clearing the infection, they can always move the driveline exit site.

They also sometimes use wound vacs as well to help with, um, healing.

Yeah, I think that was a really good learning point for me when I was a fellow was knowing to ask patients who come in with possible driveline infections, if they've had trauma to the line, or if like they accidentally dropped their battery and it like tugged on the drive line, cause that can, that alone could sort of be where your infection's coming from.

And I think we sort of.

Um, it's easy to forget to ask that.

So if, if people want to remember one thing for the first time they meet a patient and they're worried about driveline infection, they can ask about, ask about that.

And so, you know, I think we covered a lot and I, this case is certainly not as complicated, I think as, as many of the ones that we see, but are there any additional learning points you want to make sure we cover?

I think actually like the dressing site stuff is very important and it can be sort of overlooked at times.

Um, but just making sure that you're familiar with your institution's protocol related to how they take care of the driveline exit site.

And I think that that's probably, honestly, I think that that's probably one of the most important things to, to know, and to understand.

And then also just to make sure that you look at the driveline exit site whenever possible yourself, just because like looking at it in person, I know I had suggested earlier, you can always look at the pictures, but also seeing it with your own two eyes can be very helpful as well.

Yeah.

I feel like a lot of times they have those sort of clear window dressing.

So even if you can't remove it, you probably can visualize the exit site.

I think that covers most of what I want us to talk about today.

And maybe we can have you come back and talk about a more like complicated gram negative one, or let's say our blood cultures are positive.

Cause that's, that's a whole separate a wormhole that we didn't get into today.

But, um, thank you so much for coming.

Thank you so much for having me on this show.

I also would like to take this opportunity to thank my mentor, Dr.

Tina Stosor at Northwestern, who really got me into this.

She's super passionate about heart transplants and about ventricular assist device infections that you know, her enthusiasm for it made me very enthusiastic about it.

Um, and I just think that like, having a wonderful mentor has really just shaped my career greatly.

So if she's listening, thank you.

Yeah.

It makes a huge, huge difference on, on having great mentors.

Thank you so much to Rebecca for joining us for a perfectly timed heart or cardiac related case.

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