Drs. Alok Nimgaonkar and Rebecca Kumar provide an update on definitions for VAD infections!

Also mentioned in this episode is a call for the new Febrile Editorial Board!! You can find more information at https://febrilepodcast.com/editorialboard/

Episodes | Consult Notes | Subscribe | Twitter | Merch | febrilepodcast@gmail.com

Febrile is produced with support from the Infectious Diseases Society of America (IDSA)

Hi everyone.

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

We use consult questions to dive into ID clinical reasoning, diagnostics,

and antimicrobial management.

I'm Sara Dong, your host and a Med-Peds ID doc.

Before we get started in this episode, I just have a quick announcement.

As Febrile is approaching its fifth anniversary later this year, I've

been reflecting on how much this community has grown, really from

a project that I started in my basement during ID fellowship to

a resource that I'm very proud to continue to work on as junior faculty.

My goal has always been for Febrile to be your go-to for engaging and up-to-date

ID education, as well as a platform that spotlights ID trainees, our community,

the diverse career paths within our field.

But I also wanna make sure that we are adapting along the way,

expanding what we cover, and I have been considering how we can improve.

To do that, I need your help.

I am assembling a Febrile Editorial Board.

I'm looking for enthusiastic, thoughtful, and committed contributors

who want to take a longitudinal role in shaping Febrile's future.

You will truly have a direct and genuine impact on the content

and decisions related to Febrile education moving forward.

I'm looking for Podcast Editors, Visual Editors, so those who may work on

infographics or educational videos, and also Social Media Directors.

Although I have a few projects and positions that I would love to find

individuals for, I'm very much open to suggestions and ideas for roles

that I have not even imagined yet.

This will not replace our model where individuals or teams of episode writers

and guests join for one time or short series of episodes, so I still encourage

you, you know, please reach out to discuss your episode ideas if you have them.

This is really a great way to learn more about the process in

a more time-limited commitment.

But this editorial board will hopefully create a more sustainable model for this

resource and allow it to cover all of the amazing topics and people in ID.

I have posted more details.

You can find them at febrilepodcast.com/editorialboard.

There's information on roles, responsibilities, expected time

commitment, and suggested skills that would make you a good match.

If you're interested or have additional questions, also

please reach out to me directly.

Thank you so much for being a part of Febrile and listening.

Okay, back to the episode.

Let's meet our guests today.

First up, we have Dr. Alok Nimgaonkar.

My name is Alok.

I'm a third-year Internal Medicine resident at Georgetown.

Really longtime listener of Febrile, and really happy to be here.

He will be starting his ID fellowship at Columbia this summer.

And next is a return visitor to Febrile, Dr. Rebecca Kumar.

I'm Rebecca.

I am also a big Febrile fan.

I am an ID attending at Georgetown specializing in transplant.

Excited to get started.

Well, as everyone's favorite cultured podcast, we always ask if

you would be willing to share a little piece of culture, just something

that you like outside of work.

What have you guys been interested in recently?

So, yeah, I'm a longtime lover of film.

I think one movie I saw recently that was really good was

called, It Was Just An Accident.

It was nominated for Best Foreign Feature.

J ust a very moving portrait of contemporary Iran, and the

past and memory and, and trauma.

So would high-highly recommend for anyone interested.

For me, I have been listening to a lot of Turnstile recently.

They won a Grammy and they're just like a, I don't even know, I guess

they're post-punk or hardcore, but it's a little bit more pop-y than I

would say most of the hardcore that I've heard before in the past is so,

um, I've enjoyed their new album.

Nice.

I can't remember what you recommended last night.

I think it was an album of some kind.

It's been a while.

We'll have to go back.

Um, all right, well I heard we have a consult question about a

potential drive line infection.

So Alok, I'll hand it off to you.

Yeah so this is a, uh, sixty-three-year-old man with

history of HFrEF from non-ischemic cardiomyopathy of unknown origin.

He had a HeartMate 3 LVAD placed two years ago.

He's presenting with redness, pain, and drainage surrounding his driveline site.

ID is consulted for evaluation and management.

So I think before diving into this case, I think it would be helpful to

review, definitions of MCS and LVADs.

So, when we talk about MCS, what that stands for is

mechanical circulatory support, and that really describes a range of

devices but essentially all of these devices enhance systemic perfusions

in patients who have cardiogenic shock or advanced heart failure

that's refractory to interventions.

And then when we think about it even further, these MCS systems

can be classified into short term and long term support devices.

So for short term devices, these are ones that support patients through

these high risk, procedures or periods, like cardiogenic shock, for example.

To allo w us to have time to understand their prognosis, to

guide definitive treatment or serve as a bridge to transplant.

And these devices include, the Impella, which is essentially a short term

VAD, um, ventricular assist device, the intraaortic balloon pump or ECMO.

And then long-term support devices are typically used for patients

who have end stage heart failure.

And they can be used as a bridge to transplant, a bridge to decision

on whether or not somebody will qualify for a transplant, or it could

be used as a bridge to recovery.

And really bridge to recovery is pretty rare.

It only occurs in about one to 3% of patients.

And then finally what we're seeing more commonly is that it's being used

as destination therapy, meaning that this is just a device that they will

live with for the rest of their lives to help support their cardiac function.

Long-term support devices are also known as durable mechanical circulatory

support, and the most common one, and the one that we're gonna be talking

about today is the left ventricular assist device . But you can also

get biventricular assist devices or total artificial heart implantation`.

So how do LVADs work, what are their different components?

So, you know, we talked about this back in 2022 in

the episode Shape of My VAD, so if you wanna go into more detail, please

listen to that podcast episode.

But just very briefly, from the inside out, we have the pump, which if you think

about it, has a component that's in contact with the blood, where the actual

blood goes into the device, and then there's an external surface which doesn't

have any direct contact with the blood.

So the blood goes from the pump into this outflow cannula, which again also has

an area in which blood travels through.

And then there's the outside of the device.

And from there, it goes into the aorta and to the rest of the body.

And the pump itself is powered by an external battery that is connected

to the device via a driveline and the driveline tunnels from outside in

the abdomen through the, through the abdominal cavity into the thoracic

cavity where it connects to the pump.

So, how have trends in utilization of LVADs

as bridge to transplant versus destination therapy changed over time?

And what are the implications?

There's the INTERMACS study which stands for the Interagency

Registry for Mechanical Assisted Circulatory Support, which noted that

since 2022, that these newer devices like the HeartMate 3 are are exclusively

used compared to older devices, like the HeartMate, like two, et cetera.

Um, and, roughly 80% that were being put in from the years 2021 to 2023

were actually destination therapies.

And again, an LVAD is helpful because essentially there is a shortage

of donors throughout the country.

We know this.

And for patients who don't qualify for a transplant, this is an option

for them in order to live longer.

But LVADS do come with their own risks.

Stroke, thrombosis, infections, these are all complications that can happen

in patients who are living with LVADs, but since the adoption of the HeartMate

three, the risk of stroke, the risk of thrombosis have all decreased.

But, with regards to infection.

The risk is still about the same.

And the longer that you have the LVAD in, the more likely

you are to develop an infection.

So this really means that with the utilization of LVA DS for

destination therapy, that we're having patients who are living longer

with an LVAD in place and are thus more likely to develop infections.

And so I think as ID physicians, we need to have a good understanding

of these durable mechanical circulatory support devices and an

understanding of the infections that are associated with these devices.

So how has the long-term durability of LVADs impacted patient's

ability to move up on the wait list?

And why is this an issue if LVAD outcomes have improved at a comparable level

that of transplants?

Yeah, so prior to 2018, UNOS listed patients with LVA DS as

either status 1A, if they had any sort of complication or 1B if they did not.

In 2018, essentially UNOS deprioritized patients with long-term LVADs such

that only patients with essentially like a life-threatening ventricular

arrhythmia got moved to status 1 or a device malfunction or mechanical failure.

Those patients ended up as status two, but for everybody else, no

matter how long you had the LVAD in for you were considered status 3.

So even if you have an infection associated with your LVAD, the highest

you can go is only a status three.

So now what we're seeing is that these LVAD patients, even though

they were initially implanted with the thought that it was gonna be a

bridge to transplant, now it's more like a bridge to a complication.

but I do believe that there's been an update in the policy.

And Alok, I know that you have a passion for policy.

Do you wanna update us on it?

Yeah, there's actually a recent proposal that's

been accepted in June that that will allow patients with LVADs to go up

on the listing, um, based on the time that they've had their LVAD in place.

So they, if they've had their LVAD in place for six years, they'd go up to

status three, and then if they've had it for eight years, they would go up

to status two, regardless of whether they've had complications or not.

This should go into effect in September of 2026, with another phase to be

rolled out a year and a half later.

In that other phase, if I'm not mistaken, shortens

the duration of time the patient needs the LVAD for, correct?

It goes to five years, then they'll be considered status three

and then seven years, and then they'll be considered status two.

That's exactly right.

Um, now shifting gears a bit to the case.

This patient was recently hospitalized for COPD exacerbation, received a course of

antibiotics and steroids with improvement.

He lives alone and gets dressing changes frequently.

Unfortunately he got his battery caught on a chair when he was walking and

the drive line was tugged and the velour of the drive line was exposed.

He then developed redness, warmth, and pain, increased drainage

from his drive line site Um he hasn't had any fevers or chills.

No alarms have gone off on his drive line.

He denies any chest pain, urinary symptoms, cough or other symptoms.

Quickly going through his medical history, so he had HFrEF from

unknown non ischemic cardiomyopathy.

His EF declined until about 10%, he failed medical management

and required inotropic support.

He then had a HeartMate three device placed about two years

prior and since then has had a relatively uncomplicated course.

He's been on aspirin, warfarin and his INRs has been in therapeutic range.

And his LVAD is listed as destination therapy.

Other medical problems are obesity, his BMI 35 and diabetes with an A1C

of 7.1 In terms of his social history, nothing particularly relevant.

And then on exam, his vitals so he is afebrile temperature of 98.8.

His MAP is 80 and he's satting well in room air.

On exam we noticed that there's a confluent area of redness associated

with warmth, induration surrounding the driveline site with mild white-ish

drainage from the site itself.

The area's tender and without any fluctuance.

So how would you think about the initial approach to a patient with

suspected LVAD infection based on the original 2011 definitions of infections

So back in 2011, the ISHLT released guidelines on the different

types of infections, really to help guide research, diagnosis and management.

These were further divided into VAD specific infections, which are

essentially infections that are occurring because you have the VAD in place.

So that would be something like a pump infection or a driveline infection.

So it's really things that only a person with a VAD can have.

In addition to those infections, they also had VAD related infections.

So these are infections that are made more complicated by the presence of a VAD.

So bloodstream infections, endocarditis, mediastinitis, all of these things can

happen even if you don't have a VAD, but because there's a VAD in place,

the infection is made more complicated.

And then there are of course non-VAD infections.

So like even if you have a VAD, you, you can still get a UTI.

And then in addition, they basically further subclassified the infections

into definite, probable and possible based on microbiologic, clinical,

radiographic, and pathologic criteria.

So what have have been some problems with these definitions

and what is the rationale for an update?

So the uptake of these guidelines were not

as strong as had been hoped.

There was a meta-analysis of 132 studies that found only 38% use

the ISHLT guidelines for reporting infections, which makes it hard to

accurately research the epidemiology, the diagnosis, and the management of

these different types of infections.

And additionally advances in technology like such as the HeartMate 3, where

there's no longer a pocket mean that the definitions that were created,

such as a pocket infection are no longer relevant in this day and age.

And then additionally, with things like a driveline infection, the

categorization of deep versus superficial doesn't quite capture the complexity

of treatment associated with driveline infections, just based on the depth.

Um, because you could still have a superficial driveline site that has a

multi-drug resistant organism, or it could have a fungal infection that really makes

the management much more complicated.

And then in addition to this, one of the other rationales for

updating was so that the temporary devices could also be included.

So things like ECMO, the Impella, et cetera.

Um, that these definitions could be standardized across devices.

Makes sense, so what are the 2024 definitions?

Yeah, so these definitions that have been

published by ISHLT encapsulate both durable and acute MCS devices.

I did mention the acute MCS device infections, but we're

not gonna cover them here.

That's like a whole other episode, but in terms of what's

changed from a LVAD perspective.

So they've changed superficial and deep driveline infections to describe

them as complicated or uncomplicated.

And the idea is that the depth of the infection doesn't capture the complexity

of the condition, it's more like what's the organism associated with it?

There's also been a change to include blood contact surface

infections and endocarditis.

So this is essentially an infection in an area that blood flows through.

And in order to make this diagnosis, you need positive blood cultures.

You'd get radiographic or echocardiographic evidence of a

vegetation or a thrombus in the intravascular aspect of the device.

And then you could also look for septic emboli as well.

And systemic signs are likely to occur and appear, but aren't

always there for the diagnosis.

And then there's device specific bacteremia.

So this is a positive peripheral blood culture in a patient who has a

device and it's related to the device.

So an example for this would be like if somebody developed a bacteremia from a

driveline, or if they have persistently positive blood cultures greater than

72 hours apart with the same organism.

Then you also have infections involving the external surface

of the implanted device.

So this is what we would've considered previously, maybe like a pocket infection.

So the outside of the device itself is infected.

Usually to make this diagnosis you need some sort of positive

culture from the tissue or a fluid collection surrounding it.

And again, there may not be systemic signs present.

So we'll apply and then discuss the implications of management

for these definitions later in the case.

What is what's the typical diagnostic approach for patients with suspected LVAD

infections, and what is your threshold to look for deeper source of infections?

I have a pretty low threshold to look for deeper sources

of infections, but essentially when this patient comes in, I'd wanna

make sure that there's a CBC, a CMP.

I'd wanna make sure that we get cultures from the driveline exit site,

especially because of the fact that you're telling me that there is drainage.

And then in terms of blood cultures, I'd get three sets of blood cultures.

And I generally, again, would recommend getting CT chest/abdomen/pelvis, you

could potentially get an ultrasound, but I prefer looking at CT, so I'll

usually get a CT chest, abdomen, pelvis.

And then you can also consider getting an echocardiogram.

I think the important thing to keep in mind is that in larger studies of

LVAD infections, SIRS criteria only occurred in about like 39% of patients.

And so just because somebody doesn't look like "SIRS"-y based, based on labs,

like you still need to consider infection when you're evaluating the patient.

So what did the labs end up looking like for him?

So, CBC was a pretty unremarkable white count was 5.4,

hemoglobin was 13, platelets were 118.

CMP was also um unremarkable.

Electrolytes and liver function were at baseline and renal

function was also at baseline.

So the cultures we got actually ended up growing Pseudomonas which is

resistant to cefepime and ciprofloxacin, but was sensitive to meropenem.

The CT chest abdomen pelvis that we got was fortunately unremarkable for fluid

collections around the device, but did show some mild fat stranding at the

area surrounding the driveline insertion.

There wasn't any evidence of deeper infection like an abscess.

So so what are some typical pathogens that can cause infections in LVADs?

So, usually what, what I think of is gram-positives

like Staph epi and Staph aureus.

And Staph aureus is the most common pathogen overall, but

Pseudomonas is actually the culprit in about 25% of cases.

And, we do know other gram-negative organisms can

also cause infections as well.

Gram-negative rods in general, tend to cause drive line exit site infections.

The longer the patient has had the VAD in place for, and there could

be environmental factors that, that are thought to contribute to this.

Hearing that this is Pseudomonas, I would think maybe some sort of

water exposure likely led to this.

Data regarding the percentage of MDR organisms and LVAD

infections is pretty sparse.

There has been a single center study where it was estimated to occur in about

31% of patients, and I think it's also important to keep in mind that these

organisms can form biofilms and that can lead to high rates of recurrence.

So let's say the patient had systemic signs of infection

and other sources have been ruled out, um, and you're worried that

there's a deeper infection, but a CT is indeterminate or negative.

How useful are other modalities like a PET scan or a white cell tag scan

in these cases?

I mean, my personal opinion is that white cell scans in general

are trash, but I think, um, you know, CTs can have limited specificity for

ruling out deep drive line infections.

And white cell tag scans have poor sensitivity and positive predictive

values, but a PET scan on the other hand has good sensitivity

and positive predictive value.

The problem is, is that it can be very difficult to get one while a

patient's hospitalized due to the financial hurdles associated with it.

I think it can be very helpful if you're very worried that the pump or the

cannula itself is truly infected, but you have to be prepared to fight for it.

So, so bringing it back to the case, how would you

classify this patient according to the new 2024 definitions, and how would

you go about treating their infection?

So, even though what this is being described

as it's a superficial infection.

It does have the presence of MDR Pseudomonas, which would

cause this infection to actually be considered complicated.

Most simply, they'd receive two weeks, likely longer of

IV meropenem for treatment.

So, let's say this patient had a deeper

infection of the drive line.

How would you approach

management in that case?

At that point, management would involve a longer

duration of antibiotics, so like six to eight weeks or longer.

I think the other important thing is talking with your surgical

colleagues about whether or not debridement is possible.

Because he has a HeartMate three, the drive line is a modality that

is replaceable, you don't have to remove the whole device itself.

You can exchange the drive line.

So, talking to them, especially for somebody like this who's an older

gentleman, he's living by himself.

Putting him on long-term meropenem would be difficult for him to

have to administer to himself three times a day for a long time.

Makes sense and, let's say that, it was actually

susceptible to ciprofloxacin.

Would you give him chronic suppression given the high rates

of resistance for Pseudomonas.

resistance for Pseudomonas?

With Pseudomonas, essentially the fluoroquinolones

are only oral option.

Mutations and resistance are common with Pseudomonas, but I think

taking all of it together, this is somebody who I would consider giving

long-term suppressive therapy to.

How do you think about chronic suppressive antibiotics in general

for patients with these deeper infections?

What are, what are some antibiotics that you might choose?

so the data's pretty sparse and mixed with regards to

the choice of chronic suppressive antibiotic therapy for LVAD infections.

And the guidelines actually don't specifically make any

specific recommendations.

I think as long as you keep in mind that there's really not much data, and

that the two larger studies looking at LVAD infections have shown that there's

like a roughly 30% rate of relapse.

I think when you keep that in mind, you can counsel your patient and

make sure that they're aware that this is likely to still reoccur.

And then for something like Staph I'd use something like doxy or bactrim.

You could also use Keflex as well.

And then coming back to the definitions, broadly

speaking, what are the implications for management of LVAD infections

with these new definitions coming out?

In the

short term, it may cause you to think about the duration of antibiotics.

For previously defined superficial driveline infections that are actually

more complicated like the MDROs.

I think that in the long term though, it's gonna help with unified

research of devices, especially across the acute and durable mechanical

circulatory support devices.

Is there anything else coming along the horizon that

might alter the infection risk of M CS and LVAD specifically?

There's a lot of interest in transcutaneous electronic transfer

systems, which are basically not having a drive line in place, and I think

that because infections predominantly occur because of the drive line, this

would essentially reduce the risk of infections in our LVAD patients.

Thanks so much for Alok and Rebecca for joining

this update on VAD infections.

Don't forget to check out the website, febrilepodcast.com, where you'll find

the Consult Notes, our library of ID infographics, a link to that info about

the editorial board applications, as well as a link to our merch store.

Febrile is produced with support from the Infectious Diseases Society of America.

Please reach out if you have any suggestions for future shows or want

to be more involved with Febrile.

Thanks for listening.

Stay safe, and I'll see you next time.