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Ventricular Assist Device Management In The ICU
16 Plays6 years ago
In this episode of Critical Matters, we explore the role of the intensivist in the management of patients with ventricular assist devices. Our guest is Dr. John Greenwood, a practicing intensivist who splits his clinical time between the Cardiac & Vascular ICU and the ED-ICU at the Hospital of the University of Pennsylvania.
Additional Resources:
Summary of information presented during the episode kindly provided by Dr. John Greenwood: https://bit.ly/2MJdfSa
HeartWare Waveforms App for iPad: https://apple.co/2NpyQEr
Articles Mentioned In This Episode:
Pratt AK, Shah NS, Boyce SW. Left ventricular assist device management in the ICU. Crit Care Med. 2014;42(1):158-68: https://bit.ly/2MKr3M6
Sen A, Larson JS, Kashani KB, et al. Mechanical circulatory assist devices: a primer for critical care and emergency physicians. Crit Care. 2016;20(1):153: https://bit.ly/2NoreC4
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Transcript
Introduction to the Podcast
00:00:09
Speaker
Welcome to Critical Matters, a sound critical care podcast covering a broad range of topics related to the practice of intensive care medicine.
00:00:17
Speaker
And now, your host, Dr. Sergio Zanotti.
Ventricular Assist Devices (VADs) Overview
00:00:22
Speaker
Over the last decade, the use of ventricular assist devices has increased exponentially.
00:00:27
Speaker
There are a number of devices used today for a growing list of indications.
00:00:31
Speaker
Patients with ventricular assist devices may come to the ICU in the postoperative period, but may also present from the outpatient setting with complications related to long-term use of a ventricular assist device.
00:00:42
Speaker
It is very important for the intensivist to understand ventricular assist device equipment, patient physiology, and appropriate recognition and management of complications.
00:00:52
Speaker
Today's episode on the podcast
00:00:54
Speaker
is a follow-up on our initial discussion on critical care of the cardiac surgery patient with a focus on ventricular assist devices.
00:01:01
Speaker
It's a pleasure to welcome back again John C. Greenwood, who's an assistant professor of clinical emergency medicine and assistant professor of anesthesiology and critical care medicine and medical director
00:01:12
Speaker
the Resuscitation and Critical Care Unit at the Hospital of University of Pennsylvania, Department of Emergency Medicine.
00:01:18
Speaker
Dr. Greenwood divides his time between critical care and emergency medicine.
00:01:23
Speaker
Half of his clinical time is spent working in Penn's heart and vascular ICU and the other half in a relatively new EDICU space at HUP,
00:01:31
Speaker
He is the editor-in-chief of the EMRA Presser Dex and has a particular interest in the resuscitation of cardiovascular emergencies, mechanical circulatory support, and time-sensitive critical illness.
Meet Dr. John C. Greenwood
00:01:44
Speaker
Dr. Greenwood is also an administrator and contributor to Critical Care Perspectives in Emergency Medicine, a monthly CME podcast on resuscitation and critical care-related issues that can present to the ED, and
00:01:56
Speaker
and of Critical Care Project, or CCP, a multi-institutional website designed to be a multidisciplinary educational resource on topics in critical care.
00:02:05
Speaker
John, welcome back to Critical Matters.
00:02:09
Speaker
Well, thank you, Sergio.
00:02:10
Speaker
That's a kind introduction, but I really just think of myself as an intensivist that has an interest in heart stuff.
00:02:18
Speaker
So this is exciting to talk about this today.
Why Intensivists Need VAD Knowledge
00:02:20
Speaker
And as we were saying in the introduction, hard stuff seems to be growing in numbers, so even intensivists who are not working at very specialized units like yours will be exposed to these devices and need to have a basic understanding of how to manage certain complications.
00:02:35
Speaker
Wouldn't you agree?
00:02:38
Speaker
No, absolutely.
00:02:39
Speaker
I think you hit the nail on the head over the past 10 to 15 years.
00:02:43
Speaker
The number of VADs that are not only at the academic hospitals but are presenting to community hospitals because of the reasons that they're being put in is also growing in a really large volume.
00:02:58
Speaker
having one of these patients drop into your lap can be sometimes really anxiety provoking.
00:03:03
Speaker
But if you understand a few basic concepts as well as are able to recognize some common complications and initial interventions that can kind of get yourself out of the weeds, you can really turn a tough ice to unite or day into a really rewarding
00:03:22
Speaker
a word in clinical experience.
00:03:25
Speaker
So yeah, this is a great topic.
00:03:27
Speaker
I'm glad you're kind of bringing it to your audience.
VADs: Recovery, Transplant, or Decision
00:03:29
Speaker
Absolutely.
00:03:30
Speaker
So before we dive into specifics, I think it'd be important to outline the general situations in which VADs are considered today.
00:03:38
Speaker
And I think that most people will hear, oh, it's a bridge to something, but what?
00:03:43
Speaker
Maybe you can expand on that, but also this concept of destination therapy, which is a little bit foreign for most of us community ICU practitioners.
00:03:52
Speaker
Absolutely.
00:03:53
Speaker
So the concept of a bridge two is really that most VADs are designed to provide the patient with time until they reach some sort of definitive state.
00:04:07
Speaker
And that state may be recovery.
00:04:09
Speaker
So you think of the patient who's had a viral myocarditis and has basically acute heart failure.
00:04:16
Speaker
they may have a VAD placed temporarily until their heart's able to recover and the consequence of that myocarditis go away.
VADs as Destination Therapy
00:04:23
Speaker
There's also this concept of bridge to transplant.
00:04:27
Speaker
So these are patients who are young, usually have non-ischemic cardiomyopathy of some sort, sometimes familial, sometimes from other causes, who are trying to get optimized in order to be able to receive a transplant, a heart transplant.
00:04:42
Speaker
The last group largely is destination therapy.
00:04:46
Speaker
So destination therapy is usually the older individual who may not be eligible for a heart transplant, but
00:04:55
Speaker
They still are relatively well, and the concept or the goal is to allow them to achieve something.
00:05:02
Speaker
Usually it's a life event.
00:05:04
Speaker
So, you know, I like to think of these patients as, you know, the 68-year-old, 70-year-old patient who, you know, doesn't have any really comorbidities other than
00:05:18
Speaker
just one or two end organ dysfunctions, but wants to see their kids graduate college or wants to get to a point where they can go on a family trip or something like that.
00:05:31
Speaker
And these things are all taken into consideration when we look at destination therapy.
00:05:35
Speaker
So, you know, these patients do have goals in place and we'd like to try to help them achieve
Durable VADs: Life Beyond the Hospital
00:05:43
Speaker
them.
00:05:43
Speaker
And I think it's important for the intensivist to understand that
00:05:48
Speaker
With durable VADs, we'll talk a little bit about more later, these destination therapies, people can actually leave the hospital and have a meaningful extension of their life, which I think for most of us, in given circumstances, would be a big positive.
00:06:04
Speaker
No, absolutely.
00:06:05
Speaker
Quality life is something I think all of us are more in tune with.
00:06:09
Speaker
So, you know, taking into consideration what the patient wants to do and helping them get there is an important part of the intensivist job, particularly with a lot of these VAD patients.
00:06:19
Speaker
And I guess the last comment on this, and then we'll move on to more specifics, is that the bridge might also be a bridge to a decision based on uncertainty at the moment.
00:06:27
Speaker
We're not sure they're a destination therapy patient or a transplant patient or a recovery patient.
00:06:33
Speaker
and perhaps we need time to figure out what's the next step.
00:06:36
Speaker
Is that correct?
00:06:39
Speaker
That's correct, yeah.
00:06:39
Speaker
The bridge to decision is a growing group of patients receiving VADs, and this sometimes falls into the bridge to transplant or maybe a bridge that they're not going to get transplanted, but we just need more information.
00:06:54
Speaker
So we're kind of at a โ sometimes these conditions can degrade very rapidly, and we have to make a decision about how we're going to temporize the patient.
00:07:03
Speaker
And a durable VAD might provide us that time to get enough information to make a well-thought-out clinical decision.
00:07:11
Speaker
Well, let's start talking
VAD Mechanisms: Axial vs. Centrifugal
00:07:12
Speaker
more about the VADs.
00:07:12
Speaker
And I always say that there's two things that I've learned, I mean, from doing this podcast is one is that my guests are always much smarter than me.
00:07:21
Speaker
And two is that my audience is much smarter than me.
00:07:24
Speaker
So this might be a little bit over my head, but I'm sure of interest for everybody else in terms of understanding the basic physics of flow.
00:07:31
Speaker
Could we start by maybe explaining the different types of mechanism of flow, John?
00:07:37
Speaker
Yeah, absolutely.
00:07:37
Speaker
So when VADs first started being developed, they were mostly pulsatile, pneumatically driven devices that, if you think of the development of computers, they start these massive mainframes and have now gone into literally my pocket in terms of an iPhone.
00:07:52
Speaker
So they've gotten a lot smaller over time, and that's through the way the technology has advanced.
00:07:56
Speaker
So for the most part, we don't see any pulsatile VADs anymore in the community.
00:08:02
Speaker
They've moved on to two separate mechanisms.
00:08:04
Speaker
So one is axial flow and classically these would be kind of your HeartMate II devices where they're designed as the pump is basically has a central propeller that's located within the motor itself that spins around creating a vacuum on one side so that the blood is actually pushed to the other side.
00:08:24
Speaker
If you think of like a submarine propeller that's kind of how it works.
00:08:28
Speaker
Now, these types of flow devices, the axial flow devices, have to spin at a really high RPM rate that sometimes can cause friction, heat, and particularly blood damage, which can cause thrombosis, hemolysis, and is a lot less efficient than the newer generation, which are often referred to as the third generation VADs.
00:08:50
Speaker
And so the VAD market in general has moved towards what's called a centrifugal flow device.
00:08:56
Speaker
So these are a lot smaller and they're located really just in the pericardium, directly adjacent to the pericardium.
00:09:06
Speaker
And
00:09:07
Speaker
this mechanism, the flow is actually thrown out of the VAD.
00:09:11
Speaker
So the blood enters into the inlet cannula and there's a basically a fan on the inside that spins around and throws the blood towards the outer walls.
00:09:20
Speaker
And then that is then returned to the proximal aorta.
00:09:23
Speaker
Now these new generation 3 centrifugal devices you may hear of as the HeartWear device or the HeartMate 3,
00:09:32
Speaker
are much more durable.
00:09:34
Speaker
They're much more efficient.
00:09:35
Speaker
They cause a lot less blood damage.
00:09:37
Speaker
And the thought is that this is the next best step in terms of where we should go in the VAD technology market.
00:09:45
Speaker
And is there a difference?
00:09:47
Speaker
I mean, so clearly it's a progression, like you said, from pneumatic to the centrifugal kind of being the different versions, 1.0, 2.0, 3.0.
00:09:55
Speaker
But is there a preponderance of one over the other where it's durable or a temporary VAD?
00:10:02
Speaker
Right, so in, I believe it was 1994 when HeartMate 2 was FDA approved, that one was the first VAD approved for basically destination therapy.
00:10:12
Speaker
So in the community, there's a lot more of the HeartMate 2s that are out there compared to the newer generation devices.
00:10:21
Speaker
Now,
00:10:22
Speaker
They also had their own set of complications, which we'll discuss a little bit later, but I think what most academic or transplant centers are doing in terms of VADs, they've moved to this third generation centrifugal flow device because they're a lot smaller.
00:10:36
Speaker
The HeartMate 3 is still under investigation, but for bridge to transplant.
00:10:45
Speaker
But HeartWear has been FDA approved for bridge to transplant.
00:10:47
Speaker
So most, I think, insertions now have gone to centrifugal
Classifying VADs: Temporary vs. Durable
00:10:53
Speaker
flow.
00:10:53
Speaker
So you will still see HeartMate II's out there.
00:10:55
Speaker
There's plenty of them.
00:10:57
Speaker
But I think over the next five years, you'll be seeing a lot more of the newer generation devices.
00:11:02
Speaker
Okay.
00:11:03
Speaker
Why don't we talk a little bit about what are the different types of devices?
00:11:06
Speaker
Just walk us through that so that our audience can visualize all the options and the possibilities these days.
00:11:13
Speaker
Yeah, absolutely.
00:11:13
Speaker
So I think VADs come in two separate flavors for the intensivist.
00:11:18
Speaker
They're the temporary ones, and then there's the durable ones.
00:11:20
Speaker
And by temporary, I mean these are ones usually inserted by a cardiac surgeon or an interventional cardiologist or maybe even an interventional radiologist at some places or cardiology designed to provide temporary support for a patient who's had an acute cardiovascular collapse or insufficiency, might be in a cardiogenic shock.
00:11:39
Speaker
So from a cardiac surgery standpoint, the
00:11:43
Speaker
One of the more common devices would be the Centromag device, and that's basically an external VAD that's surgically implanted into the patient.
00:11:52
Speaker
It's a centrifugal pump.
00:11:54
Speaker
It can be run for a long period of time, even though it's only FDA-approved for about six hours.
00:11:59
Speaker
This can run for days to weeks to maybe even longer.
00:12:02
Speaker
It can provide 10 liters of flow at any given time, and it's usually implanted at this point for acute RV failure after an LVAD or after cardiac surgery.
00:12:15
Speaker
It's a large basically inflow-outflow cannula system, so it usually utilizes a 22 French outflow, and whenever the directions always can be kind of confusing, but
00:12:28
Speaker
It's always kind of centered on the device rather than the patient.
00:12:32
Speaker
So an outflow is going from the patient to the device.
00:12:35
Speaker
So it's a 22 French outflow cannula to the VAD itself and then a 32 French, sorry, to the patient.
00:12:44
Speaker
So if you have a classic configuration would be something like left atrium to the aorta or the right atrium to the PA depending on which ventricle has failed.
00:12:55
Speaker
Now, there's a couple other devices that are temporary that may be seen.
00:13:00
Speaker
So the Tandem Heart, particularly in the community, the cardiologists are particularly utilizing these more and more with the complicated PCIs.
00:13:11
Speaker
So a patient comes in with a STEMI.
00:13:13
Speaker
They go to put a stent in, and they crash.
00:13:17
Speaker
This is a common device used particularly for transferring the patient to an academic clinic.
00:13:24
Speaker
institution who may have more resources.
00:13:27
Speaker
These are temporary centrifugal VADs.
00:13:30
Speaker
They're inserted percutaneously and the blood is basically taken out of a 21 French femoral vein that is basically inserted so it's transseptal into the left atrium and then it's returned to the femoral artery.
00:13:44
Speaker
So it's almost like a VA ECMO type system
00:13:47
Speaker
But it's a little bit more durable, and that can provide support for up to about four liters a minute.
00:13:53
Speaker
So if your patient's in cardiogenic shock, that may be just enough to get them through their transfer.
00:14:03
Speaker
And we were talking a little bit prior to the podcast about something that you're seeing more frequently, which is the impella.
00:14:11
Speaker
And I think this is an exciting kind of technology that it also is being used more frequently.
00:14:18
Speaker
This is a temporary axial flow device that's inserted percutaneously again.
00:14:24
Speaker
And there's a couple of different types.
00:14:27
Speaker
So there's an assist device.
00:14:28
Speaker
impella that provides about two and a half liters of flow.
00:14:31
Speaker
There's a full support that provides about five liters of flow.
00:14:36
Speaker
And then just introduced, I think over the past six months, is a right ventricular impella called RP impella that can be inserted for RV failure.
00:14:46
Speaker
So these are a little bit different.
00:14:49
Speaker
in that the device actually sits within the ventricular cavity and through an axial flow mechanism sucks blood out of one compartment, usually the ventricle, and then is basically spun around and ejected out into either the aorta or the PA to provide supportive flow.
00:15:09
Speaker
And these also, like you said, might be a bridge to recovery, which means that they're used for a short amount of period of time with the intention of being removed once the patient's heart function improves, correct?
00:15:23
Speaker
That's absolutely correct.
00:15:24
Speaker
Okay.
00:15:28
Speaker
So tell us a little bit about the durable VADs, John.
00:15:30
Speaker
Those, I think, that are more in the realm of the specialized units.
00:15:33
Speaker
But like we mentioned earlier, somebody who has a durable VAD might end up in any hospital emergently.
00:15:40
Speaker
And I think that understanding that is probably important for all our intensivists.
00:15:46
Speaker
Sure, absolutely, Sergio.
00:15:47
Speaker
So I think it's probably, depending on where you work, you may see these right out of the OR, or they could land in the emergency department for a short period of time while awaiting transfer.
00:16:01
Speaker
But I think it's important.
00:16:04
Speaker
We already kind of went over the indications, but just knowing some of the basics about which devices are out there, what they're trying to accomplish within the patient,
00:16:15
Speaker
and then also kind of some of the potential complications that you could be dealing with for a few hours while you're waiting for transport to arrive.
00:16:24
Speaker
So I think that one of the
00:16:27
Speaker
most important concepts of any VAD itself, particularly an LVAD, is that VADs are preload dependent and afterload sensitive.
00:16:37
Speaker
So VADs are not smart devices at all.
00:16:40
Speaker
Like they are not like pacemakers that can change the number of impulses per minute or anything.
00:16:46
Speaker
They are set and whatever's going on with the patient will impact the ability of that VAD to work.
00:16:53
Speaker
So it will suck blood out of one
00:16:56
Speaker
basically box, which is usually the ventricle, and move it to another box, which is bypassing that ventricle to usually the aorta.
Key VAD Parameters
00:17:03
Speaker
So if there's no blood in the left ventricle, then the VAD won't work.
00:17:08
Speaker
So that's what I mean by saying they're preload dependent.
00:17:11
Speaker
Now, if I took a set of pliers or a clamp and added pressure to clamp the aorta, obviously the VAD wouldn't work all that well.
00:17:20
Speaker
because it would be up against a very high afterload.
00:17:23
Speaker
So the efficiency or ability of that VAD to work is dependent upon the patient's afterload or blood pressure to be within a certain range, but that doesn't make it impossible to work.
00:17:36
Speaker
So preload dependence, afterload sensitivity is an important concept.
00:17:41
Speaker
And then
00:17:42
Speaker
We're going to touch briefly upon the different variables that you might see on the bedside console or the patient controller, but the only thing that actually can be prescribed by a physician or a VAT engineer or whatever is the speed.
00:17:58
Speaker
So you can control how fast that impeller is spinning around.
00:18:03
Speaker
But the rest of the stuff is basically feedback you're getting from the patient in terms of how that FAD is actually working.
00:18:11
Speaker
So if we want to go ahead.
00:18:13
Speaker
No, so I was going to say that I think in terms of understanding this is very important.
00:18:17
Speaker
And like you mentioned, John, a.
00:18:21
Speaker
flow or our output is going to be directly proportional to the speed that we can set, the only thing we can set, and inversely proportional to the difference in pressures between the
HeartMate 2 vs. Centrifugal Devices
00:18:33
Speaker
inflow and the outflow, which is basically governed by our preload and our afterload, correct?
00:18:40
Speaker
That's absolutely correct.
00:18:42
Speaker
So if we had to look at some of the current devices, we talked specifically about one axial flow and then a couple centrifugal flows.
00:18:51
Speaker
So the axial flow device, the HeartMate 2, is the flow that it can provide is usually anywhere between 3 and 10 liters a minute.
00:19:01
Speaker
Now, one thing about flow is that when you look at the bedside console, it tells you the flow on the VAD.
00:19:07
Speaker
That's not the actual flow.
00:19:09
Speaker
It's not exactly like what a patient's cardiac output is.
00:19:14
Speaker
It's a calculated number that's based on the power as well as the set speed of the device.
00:19:19
Speaker
So it's an estimate, but it's not perfect.
00:19:22
Speaker
And the other reason for that is because the patient may also be ejecting blood out of the aortic valve.
00:19:27
Speaker
So there's only a fraction that's actually going through the VAD itself.
00:19:31
Speaker
So whenever I see a flow number, I'm always kind of like taking that with a grain of salt.
00:19:36
Speaker
Obviously, we want it to be within a certain range, but you have to take it into clinical context.
00:19:41
Speaker
Now, remember, I said axial flow devices are a lot less efficient.
00:19:45
Speaker
So the speed of the VAD, particularly HeartMate 2s, is a lot faster.
00:19:50
Speaker
So it spins at about 8,000 to 10,000 RPMs.
00:19:55
Speaker
Now there's this other term called pulsatility that you'll see, and the way I like to think about that, that's the sort of the native contribution of the heart.
00:20:03
Speaker
So remember, our hearts are pulsatile, they're not continuous flow.
00:20:06
Speaker
We have a pulse pressure on the monitor.
00:20:09
Speaker
So the higher the pulsatility, I try to explain that to my fellows and residents as that's kind of how much native contribution your heart is providing to the patient's cardiac function at the moment.
00:20:23
Speaker
And that can fluctuate up and down.
00:20:25
Speaker
And normal for HeartMate 2 is usually between a number of like four and five.
00:20:30
Speaker
There's also an estimate of power.
00:20:32
Speaker
So the power is termed in watts.
00:20:34
Speaker
And again, the HeartMate 2 is the axial flow devices.
00:20:39
Speaker
So I put all this information in the handout and so I'll try not to get too much into the specific normal ranges just because you can refer to the handout and take a look at it.
00:20:49
Speaker
Now, so again, we're talking about the variables of the VADs.
00:20:52
Speaker
That's flow, speed, pulsatility, and power.
00:20:56
Speaker
Those are the four main things that if you call a VAD engineer or coordinator in the middle of the night, they're going to want to know about that patient.
00:21:05
Speaker
So if we move to the centrifugal devices, those are the heartwares, the HeartMate 3s, and in general they provide a similar rate of flow, so usually above three liters, three to eight, three to six liters a minute.
00:21:15
Speaker
But the one thing you'll notice is that the speed's a lot less.
00:21:18
Speaker
The RPMs are usually set much, much lower, about 25% of what the HeartMate IIs are.
00:21:23
Speaker
So they're about 3,000 RPMs, give or take 1,000 RPMs in general.
00:21:29
Speaker
The cool thing about the HeartWares is that their patient console actually provides some waveform data.
00:21:37
Speaker
So you can actually see how pulsatile the patient is through the waveforms that are on the screen, as well as some of the numbers that you get.
00:21:44
Speaker
So I encourage everyone to, if you have an iPad, definitely check out the Heartware Waveforms app on iPad.
00:21:52
Speaker
You can go to the App Store and search for Medtronic or Heartware and it'll come up, but this is a really cool educational tool that you can actually go through and you can change certain settings on the simulated VAD and see how it responds and see how the patient would respond.
00:22:09
Speaker
So it's a great little
00:22:11
Speaker
educational tool to go through and kind of get more comfortable with the settings of the VAT and certain clinical conditions, like if a patient has a GI bleed or hypovolemic or hypertensive, you can kind of see how the VAT will respond in those clinical scenarios.
00:22:25
Speaker
So definitely worth a little bit of time.
00:22:28
Speaker
And we'll put those in the show links.
00:22:30
Speaker
There'll be a link, I mean, to that app alongside some references that John has provided and the summary that he referred to.
00:22:37
Speaker
So I think that an important concept here with understanding...
00:22:42
Speaker
these settings, the flow speed, the PI, the power, is really that if we have a call to a VAD rep, which is an important part of troubleshooting, that information we need to know and be able to translate.
00:22:55
Speaker
But also, as we'll talk a little bit more, I guess, when we talk about hemodynamics, is that
00:23:00
Speaker
changes in these parameters are probably more valuable than the absolute number, like you said, and these changes, depending on which direction and which combinations, might point us down different differential diagnosis, right?
00:23:14
Speaker
Absolutely, yep, that's correct.
00:23:16
Speaker
And one thing I forgot to mention too, HeartMate 2 also, if you go to their website, you can literally play with HeartMate 2 controller and it'll walk you through how to see the alarms and stuff like that.
00:23:27
Speaker
So it's another sort of teaching tool there.
00:23:30
Speaker
But absolutely, your VAD engineers or your VAD nursing coordinators, they're going to want to know those basic settings.
00:23:40
Speaker
And if I could
00:23:43
Speaker
get one thing across to the audience.
00:23:46
Speaker
Talking to a family member, the family members of these patients literally know everything about their patient's VAD.
00:23:55
Speaker
They go through extensive training on how to kind of work with it, know what the alarms mean.
00:24:00
Speaker
So if you have any questions whatsoever, don't feel embarrassed about asking patients' family, hey, have you had any alarms?
00:24:06
Speaker
Can you show me, you know,
00:24:09
Speaker
Go through with the family member, have they had any complications in the past?
00:24:13
Speaker
They are a wealth of information, particularly related to the patient's history
Postoperative Care and Handoff for VAD Patients
00:24:18
Speaker
with that VAD.
00:24:18
Speaker
So utilize family liberally if they show up to your ICU.
00:24:24
Speaker
Excellent.
00:24:24
Speaker
And I think that, like we mentioned at the beginning, there's two situations in which most intensivists get exposed to these.
00:24:30
Speaker
But we believe that in a lot of community settings, it might be an immediate post-operative period of somebody who is being bridged to either a destination therapy transplant or being moved to another hospital.
00:24:44
Speaker
So why don't we start talking about that transition from the OR into the ICU?
00:24:49
Speaker
In our last podcast that we did together, John, we did talk about
00:24:53
Speaker
importance of appropriate handoff and I presume like in any other situation there are particular aspects of the handoff in this patient population that are important.
00:25:02
Speaker
Do you want to start with those?
00:25:05
Speaker
Absolutely.
00:25:06
Speaker
So in terms of important things on this handoff in addition to kind of the usual operative course why the device was implanted is going to be critical.
00:25:15
Speaker
Was this a planned or an unplanned
00:25:18
Speaker
initiation of VAD therapy.
00:25:20
Speaker
Now again, usually common things being common, over the years the most common cause for a temporary VAD is postcardiotomy shock.
00:25:30
Speaker
So we did a CABG, the patient couldn't come off bypass, and so we put in a temporary VAD to bridge him to recovery or to some other surgical plan.
00:25:41
Speaker
that's going to happen the next 24 to 48 hours.
00:25:44
Speaker
Now, hopefully for the patient, this was a planned intervention and maybe this was advanced heart failure bridge to recovery or destination, and we're going to walk through kind of what the goals are in that immediate post-operative period.
00:26:00
Speaker
So at the end of their OR course, sort of after the VAD's implanted, your post-operative TEE is going to have a lot of really important information that you're going to want to get from your cardiac anesthetist.
00:26:14
Speaker
And the important parts of that TEE are going to be the evaluation of the LV cavity and size.
00:26:21
Speaker
So oftentimes, after the VAD
00:26:25
Speaker
is implanted.
00:26:26
Speaker
They'll titrate the speed so that the LV's end diastolic diameter is less than 10 millimeters or whatever number they decide to go to, but that the cavity is decompressed.
00:26:39
Speaker
And they're also going to want to make sure that the septum is in the midline and it's not bowed towards the RV or bowed towards the VAT itself.
00:26:48
Speaker
So these VADs are actually positioned so that the inflow to the VAD itself is right in the apex and pointing towards the mitral valve.
00:26:56
Speaker
So you want to ask, hey, was the VAD positioning okay after insertion?
00:27:01
Speaker
You're also going to want to know about what the aortic valve was doing after the VAD was implanted.
00:27:07
Speaker
So was it opening or was it not and did the surgeon decide there was some degree of aortic insufficiency so they electively stitched closed the aortic valve?
00:27:18
Speaker
That's going to be an important piece of information as it's going to obviously impact kind of what you're seeing on the monitor and also kind of the flows that are going through the VAD itself.
00:27:29
Speaker
You're also going to want to know a little bit about the outflow cannula.
00:27:32
Speaker
So all these VADs, so blood goes into the VAD, it goes out of outflow cannula and is returned to 99% of them returned to the proximal aorta.
00:27:41
Speaker
So how did the outflow cannula look?
00:27:43
Speaker
Was it compressed at all?
00:27:44
Speaker
Was it kinked on closure?
00:27:46
Speaker
Was there good flow going through it?
00:27:48
Speaker
And then lastly, what the right ventricle look like.
00:27:51
Speaker
So all of a sudden you're in this clinical condition where this patient might have been getting by with, if there were an elective placement, with a cardiac index of about 1.5 for the past year, and now all of a sudden you're flowing four liters a minute.
00:28:08
Speaker
that right ventricle is now left with dealing with a lot more venous return.
00:28:12
Speaker
So you want to know, was the right ventricle functioning okay?
00:28:15
Speaker
Was it dilated at all coming out of the OR?
00:28:18
Speaker
And then obviously, what are the vasoactives that are on at the moment?
00:28:22
Speaker
So as you move from your cardiac anesthetist to your cardiac surgeon,
00:28:28
Speaker
you're going to want to say, hey, what are your hemodynamic goals here?
00:28:31
Speaker
Like, what do you want your blood pressure to be?
00:28:32
Speaker
What's the goal flow?
00:28:34
Speaker
And then what's the current speed?
00:28:37
Speaker
And were you happy with it coming out of the OR?
00:28:40
Speaker
And likely they'll have some specific requests related to those types of titratable things.
00:28:48
Speaker
So I think in the immediate post-operative, like you mentioned, one of the biggest challenges probably in the first hours, like any of our cardiac surgery patients, is the hemodynamic management.
Managing Hemodynamics Post-Surgery
00:28:57
Speaker
Can we dive into a little bit of that, John?
00:29:02
Speaker
Sure.
00:29:02
Speaker
So blood pressure management usually coming out of the OR is by arterial line, usually a femoral radial arterial line.
00:29:11
Speaker
And the patients themselves usually don't have that much intrinsic heart function to begin with.
00:29:16
Speaker
So they can't generate a meaningful pulse pressure.
00:29:19
Speaker
So what that means is when you look, obviously, when you're looking up the monitor, you'll often see a relatively flat A-line tracing.
00:29:25
Speaker
You may see little blips here and there in between with each beat, and that's your aortic valve opening, and that's a good thing.
00:29:32
Speaker
But you might not see all that much activity.
00:29:35
Speaker
Now the other trouble with that is that sometimes that can make it really challenging to get a pulse ox because there's not that much variation in flow so the pulse ox sensors can get really confused as to what's going on.
00:29:46
Speaker
So you may be left with doing some frequent blood gases right off the bat to make sure your oxygenation's at target.
00:29:54
Speaker
And so I've mentioned for aortic insufficiency, the surgeon may have elected to place what's called a park stitch.
00:30:01
Speaker
They may come out and be like, yeah, we put a park stitch in because of moderate to severe aortic insufficiency.
00:30:08
Speaker
And what that is, is they basically take a suture and they suture through the aortic valve leaflet so it stays closed to prevent excessive aortic regurgitation.
00:30:20
Speaker
So if you hear someone say park stitch, that's just what they mean by that.
00:30:23
Speaker
Now, in general, I think most would agree that the MAP goal after NALVAD placement is somewhere between 70 and 90 milligrams of mercury.
00:30:33
Speaker
And that's a pretty consistent number because most of the VADs, when they're designed, they're designed using these pressure flow curves, using the afterload of the patient and a normal filling pressure.
00:30:46
Speaker
So they operate most efficiently, usually within that range of 70 to 90.
00:30:49
Speaker
Now,
00:30:51
Speaker
Over time, you may relax that goal and allow a little bit of a lower MAP goal, but in the initial, in the first few hours after they come out of the OR, I really try to keep it within that range so that I can try to keep as much constant as I can.
00:31:06
Speaker
And remember, like we were talking about, and Sergio, like you nicely pointed out, that the VAD performance and flow is directly related to the afterload, or what some people call the pressure head.
00:31:16
Speaker
So keeping good control of the MAP after surgery is important.
00:31:22
Speaker
Because what can happen is if the patient starts waking up and maybe you weren't ready for them to be excibated quite yet, they can get hypertensive, that can really drop your VAD flows down and has been implicated in an increased incidence of acute ischemic stroke, excessive bleeding, and in some cases, pulmonary congestion, heart failure type symptoms.
00:31:47
Speaker
In addition to your arterial line, you're also going to take a look.
00:31:49
Speaker
Most of these patients will come out with a PA catheter that you can use to titrate your inotropes.
00:31:54
Speaker
Usually a patient will be on some form of inotrope, whether that's epinephrine or milrinone, vasopressors, and that's also still really helpful in identifying things like postoperative tamponade, loss of domain, as well as RV dysfunction or failure.
00:32:11
Speaker
Now,
00:32:13
Speaker
If you do find yourself in a situation where the patient's getting more hypotensive or you go to the nurse and check in, like, hey, I'm going up on my norepinephrine, my vasopressin, my pressor requirement's going up,
00:32:24
Speaker
and you take a look at your VAD bedside controller and you notice that the VAD flows are dropping, things you want to start thinking about is, hey, am I losing volume?
00:32:34
Speaker
Is my patient bleeding?
00:32:36
Speaker
Or is the flow dropping because the left ventricle is underfilled and maybe the right ventricle is dilating?
00:32:44
Speaker
And so you might want to get a quick echo or TEE.
00:32:47
Speaker
And then lastly, sometimes, particularly in these bridge-to-decision patients, they may be overweight or in some cases morbidly obese.
00:32:57
Speaker
And the reason they're bridge-to-decision is because they need to lose weight before heart transplant.
00:33:01
Speaker
They can have a really stiff chest wall.
00:33:03
Speaker
And after closure, that can sometimes impact the
00:33:07
Speaker
patency of the outflow cannula or what's often referred to as loss of domain.
00:33:12
Speaker
So they have this new device that's occupying real estate within the mediastinum and when you closed up that sternum things get compressed somewhat unintentionally or they may swell over the first few hours out of the OR and if that swelling causes compression of the ventricle or the right ventricle can create a tamponade like phenomenon that's called loss of domain.
00:33:35
Speaker
They may not have
00:33:36
Speaker
traditional tamponade with fluid around the heart, it may just be an extrinsic compression from the chest wall itself.
00:33:43
Speaker
And with any of these devices in the cardiac surgery, I think that anticoagulation and potential bleeding are always also a fine line that we need to manage.
00:33:52
Speaker
And I'm sure that it's very important in the immediate post-operative situation.
00:33:56
Speaker
Can you comment a little bit on that,
Anticoagulation and Bleeding Risks
00:33:58
Speaker
John?
00:33:58
Speaker
Yeah, so in
00:34:01
Speaker
In the early post-operative phase, usually anticoagulation will be started somewhere between the first six to 24 hours after you're sure that the patient's not actively hemorrhaging after they come out of the OR.
00:34:13
Speaker
Anticoagulation strategies really vary depending on the institution.
00:34:18
Speaker
Most places will start the patient on some form of antiplatelet, and usually that's aspirin.
00:34:23
Speaker
Some places even use platelet function tests to
00:34:27
Speaker
determine whether or not they need to be on some other antiplatelet as well.
00:34:31
Speaker
And then the other side of that is the work on therapeutic heparin with a bridge to Coumadin therapy.
00:34:39
Speaker
Now, the usual outpatient target INR, somewhere between one and a half to two and a half,
00:34:44
Speaker
But depending on the device, maybe higher or maybe of the previous complications, an INR of three.
00:34:51
Speaker
So it would be important to talk to your cardiac surgeon about what their goals are for anticoagulation, whether that's initial PTT goals, and then obviously bridging to more longer-term anticoagulation with Coumadin, what their target INR is.
00:35:06
Speaker
So bleeding in general though, whether or not it's in the acute postoperative phase or as an outpatient, is the most common VAD-related complication.
00:35:16
Speaker
In fact, about a quarter of VAD patients will need some sort of surgical intervention as a result of either postoperative bleeding or outpatient bleeding.
00:35:24
Speaker
And the most common locations are largely mediastinal, the thoracic pleural spaces, as with most post-cardiac surgery or post-cardiotomy patients.
00:35:35
Speaker
But the longer the patients are on VADS, the higher risk they're at for mucosal bleeding, particularly GI bleeds, whether it's upper or lower mucosal bleeds, such as epistaxis.
00:35:48
Speaker
And so those are going to be the ones that usually present coming in through your emergency department
00:35:55
Speaker
And so there's some reasons for that.
00:35:57
Speaker
Now, this may be due to super therapeutic anticoagulation, and that's possible.
00:36:02
Speaker
These patients often can fluctuate, and you want to keep relatively tight control of what their anticoagulation targets are.
00:36:11
Speaker
But VAD patients also develop a secondary coagulopathy from kind of the mechanism of the VAD itself.
00:36:16
Speaker
So if you think about
00:36:20
Speaker
how blood is handled as it goes through the vat, it's going through a spinning device that can cause a lot of shear forces on your platelets as well as other blood products.
00:36:29
Speaker
So it can basically create what's considered an acquired von Willebrand syndrome that can cause platelet dysfunction.
00:36:38
Speaker
that makes them at higher risk for not being able to form a clot properly.
00:36:43
Speaker
And so they're at higher risk of bleeding.
00:36:44
Speaker
So something that considers you're trying to maybe provide, if your patient's bleeding, how you're going to address that clinically might be due to more platelet transfusions, fibrinogen transfusions, something like that.
00:36:57
Speaker
I mentioned as an outpatient, patients have more increased incidence of GI bleeds.
00:37:02
Speaker
And the reason for that is so when you move to like this pulsatile flow state, which is a normal heart, to a continuous flow state with a VAD,
00:37:12
Speaker
there's pretty much an equilibration of pressures between the arterial and the venous side, particularly at the capillary level.
00:37:20
Speaker
So these patients are really high risk of developing AVMs, and it seems to happen most frequently in the GI tract.
00:37:27
Speaker
And so it's not uncommon that we'll have patients who are now anticoagulated and come in with these massive GI bleeds, and it's found that they have AVMs in their colon or even in their upper GI tract, which can be a little bit more challenging.
00:37:40
Speaker
So, definitely something to think about in the hypotensive patient who comes in from the outpatient setting and maybe has a bleed or has a concern for bleed.
00:37:49
Speaker
This may be due to an AVM.
00:37:51
Speaker
So, how you might want to start or address that may be something to be discussed before if your patient's ramping up to become a VAD center.
00:38:00
Speaker
Now, in terms of general goals, I think hemoglobin targets are kind of the usual range.
00:38:07
Speaker
around 8 to 10 milligrams per deciliter for most VAD patients.
00:38:12
Speaker
And like we mentioned at the beginning, a lot of these patients might be potential candidates for transplant.
00:38:18
Speaker
Are there any important considerations in terms of transfusions and selection of type of blood?
00:38:24
Speaker
I think that's something that a lot of times people who are not exposed to these patients is something that we don't consider as well.
00:38:31
Speaker
It's a great question, Sergio, and this is a really important point.
00:38:34
Speaker
So when the patient comes in, if you're talking to family members or the patient trying to figure out why they have the VAD placed, if they are a bridge to transplant, it's important if you're going to transfuse them with anything that they get leuker-reduced radiated blood products because obviously you don't want to increase their PRA risk or their ability to receive a transplanted organ.
00:38:56
Speaker
every transfusion, I'm sure we've all heard, every transfusion is like a mini transplant.
00:39:01
Speaker
So the amount of antibodies they're exposed to goes up exponentially with each transplant.
00:39:05
Speaker
So we really try to avoid red blood cell transfusions if at all possible.
00:39:11
Speaker
However, the caveat to that is if the patient's in front of you and is exsanguinating, you have to keep the patient's best interest in mind, and that may require blood product transfusion.
00:39:23
Speaker
Now there's a lot of people that are uncomfortable with this anticoagulant patient because they're like, oh well can I reverse them because I don't want the VAD to clot off.
00:39:32
Speaker
And that's probably a perpetuated myth.
00:39:34
Speaker
So there are one or two small studies that actually looked at VAD thrombosis with reversal of anticoagulation and a number of these in this case series were result of GI bleeds.
00:39:46
Speaker
And
00:39:47
Speaker
In none of them did the patient have an acute thrombosis of their VAD with reversal of the anticoagulation.
00:39:55
Speaker
So how I approach this is I'm not using PCC to reverse their Coumadin because of the increased thrombosis risk of that.
00:40:03
Speaker
But using something like FFP and vitamin K, stuff like that to temporarily reverse their anticoagulation is perfectly safe.
00:40:11
Speaker
And obviously, this is all done in conjunction with the VAD team.
00:40:15
Speaker
But certainly, don't feel like your back's against the wall.
00:40:19
Speaker
You can reverse them if they're bleeding excessively and unstable in front of you.
00:40:23
Speaker
And I think that a point that maybe be the opposite extreme of the situation, but I think is important for our audience, is that you can have acute thrombosis of your VAD, even in the presence of a therapeutic or super therapeutic INR.
00:40:39
Speaker
So that should not lead you to the conclusion, oh, it's probably not thrombosis because the INR is four.
00:40:45
Speaker
Correct?
00:40:46
Speaker
Correct.
00:40:48
Speaker
Yeah, that's a great point.
00:40:49
Speaker
So about five years ago now, in New England Journal, there was a report of increased risk of or increased incidence of thrombosis, particularly with the HeartMate 2 devices.
00:40:59
Speaker
And this created quite a scare in the VAD community.
00:41:02
Speaker
And since it maybe changed some of the practice strategies for anticoagulation and particularly around HeartMate 2s.
00:41:09
Speaker
So if you're concerned about thrombosis being like you have low flow alarms, high power,
00:41:15
Speaker
Some things that you can do, look for things like hemolysis, so if the patient has new hematuria, you can send an LDH or even a plasma-free hemoglobin and get a quick echo because oftentimes you'll see a distended left ventricle if there is in fact a VAD thrombosis.
00:41:33
Speaker
But these patients can certainly be therapeutic on their anticoagulation.
00:41:37
Speaker
We do know that any coagulation, the coagulation cascade in all these patients is all thrown off, so it's certainly a risk even if they are therapeutic.
00:41:50
Speaker
So why don't we dive into some of the common complications that occur with these
Right Ventricular Failure: Early and Delayed Risks
00:41:54
Speaker
patients?
00:41:54
Speaker
And I think for our audience, it's important to recognize that these complications can occur in the immediate postoperative period, but also can occur in patients who have the VAD for a longer period of time.
00:42:05
Speaker
Want to start with right ventricular failure, John?
00:42:09
Speaker
Sure, that sounds like a great spot.
00:42:12
Speaker
So RV failure is an important one to keep an eye out for, particularly in the early perioperative period, and sometimes even up through the first month after patients had a VAD in place.
00:42:24
Speaker
And this is from a number of different reasons that are a number of different causes can actually lead to a patient developing right ventricular failure after a VAD.
00:42:33
Speaker
So after the LVAD is put in, there's often a change in geometry of the right ventricle.
00:42:38
Speaker
So you're now mechanically unloading what used to be a dilated left ventricle and causing the septum to kind of shift over more towards the free wall, the LV.
00:42:49
Speaker
And what this will do is essentially it expands the size or dilates the right ventricle sometimes, which allows for increased venous return due to the VAD now contributing to the patient's cardiac output.
00:43:02
Speaker
Now these patients also often have underlying secondary pulmonary hypertension from chronic heart failure or maybe even their underlying disease.
00:43:12
Speaker
So it kind of is a double whammy on the right ventricle.
00:43:15
Speaker
So you have increased RV afterload that's at the baseline or maybe even worsened temporarily in the postoperative phase from hypoxemia or maybe some pulmonary edema.
00:43:27
Speaker
And now you've also given it a new increased flow load to deal with.
00:43:32
Speaker
And in a tenuous patient, this can be a really challenging physiologic scenario for the right ventricle to deal with.
00:43:39
Speaker
So things that might cue you in and maybe a patient who's having a slight increase in vasopressor inotrope requirement when you get called to the bedside, take a look at the VAD console itself.
00:43:49
Speaker
If the flows have dropped, if there's minimal pulsatility, that can give you a sign that the left ventricle is empty.
00:43:56
Speaker
And sure, this may be due from under-resuscitation,
00:43:59
Speaker
But if you take a look and you see that CVP climbing, you have to be concerned about RV failure and even tamponade.
00:44:09
Speaker
So if you look at the hardware, let's say it's a hardware device and you can actually see the waveforms on the device itself, you'll notice that the waveform will often be flat.
00:44:18
Speaker
And if you have a flat waveform on your VAD bedside console, that's a concerning sign that the LV is empty.
00:44:28
Speaker
And oftentimes, the analogy I put is, so when your heart's doing more of the work, you're more pulsatile, but when the VAD's doing all the work, you're less pulsatile, and that waveform might even be flat.
00:44:40
Speaker
So that flow waveform is going to be a nice little bedside tool or bedside sign to look for in terms of how much is the VAD contributing versus how much is the patient's native left ventricle contributing to cardiac output.
00:44:54
Speaker
So if you are concerned about early right ventricular failure, some standard interventions that you can do to kind of help improve the physiologic scenario for the right ventricular to perform and maybe even recover.
00:45:09
Speaker
So oftentimes, if they're not already on, inhaled pulmonary vasodilator like epiproxenol or in some cases nitric oxide, we'll get that started.
00:45:19
Speaker
Assuming they still have a reasonable blood pressure with minimal vasopressor requirements, an inodilator like milrinone is often started relatively quickly.
00:45:28
Speaker
And if you don't have enough blood pressure to start milrinone, ramping up your epinephrine as your inopressor, if you will, is an important initial step to kind of support that right ventricle.
00:45:43
Speaker
if it's struggling.
00:45:45
Speaker
You may even need to paralyze the patient to minimize your intrathoracic pressure if things start really getting out of hand.
00:45:52
Speaker
And obviously early surgical consultation, getting your cardiac started, hey I'm really concerned about this right ventricle, because it's not uncommon that they'll put in a temporary RVAD so you're not maxing out on your vasopressors
00:46:04
Speaker
and really flogging the patient early on.
00:46:07
Speaker
You know, a right ventricle with new liver congestion, liver failure, those VAD patients never do well.
00:46:14
Speaker
So it's something to really stay on top of.
00:46:18
Speaker
Now, one other small point that's worth touching upon is, let's just say the patient's doing great, and the surgeon comes by, and this happens every now and then, and they're like, I want the vasopressors off, they look great, turn off the epi, let's get them extubated, looks great.
00:46:37
Speaker
Sometimes with rapid de-escalations, and particularly after extubation, that's a high risk time for the right ventricle, and you can have delayed right ventricular failure.
00:46:47
Speaker
So moving away from a positive pressure, positive intrathoracic pressure environment with intubation mechanical ventilation to a negative inspiratory pressure system can also hit the RV with increased preload and lead to progressive overload and failure.
00:47:04
Speaker
And we've had a couple of these at Penn where everything looks great, they get extubated, they even get downgraded to the floor, and day four, day five, they come back not looking well, and it's just that they're
00:47:16
Speaker
right ventricle pumped out.
00:47:17
Speaker
So definitely something that you're not out of the woods at even after the patient's extubated and transitioning out of the ICU.
00:47:24
Speaker
So I think something to always keep in mind and obviously the ultimate treatment I think for RV failure, we're unable to really get it better with the interventions you mentioned, would be to go to a right ventricular assist device, right?
00:47:37
Speaker
Yeah, that's correct.
00:47:38
Speaker
And that's our preferable sort of route or exit strategy, if you will.
00:47:47
Speaker
Okay.
00:47:48
Speaker
So why don't we talk a little bit about this suction episodes or suck down, which I think is something very particular to the VAD world that a lot of us might not be as familiar with.
00:48:00
Speaker
Yeah.
00:48:00
Speaker
So there's a...
00:48:03
Speaker
This is fairly common.
00:48:04
Speaker
You can get into this situation.
00:48:06
Speaker
So suck down is just a generic term used for if, like I said, these VADs aren't very smart.
00:48:12
Speaker
So the VAD knows to suck things into it.
00:48:15
Speaker
And if the left ventricle is underfilled, well, it's going to just suck in myocardium.
00:48:20
Speaker
So suction events can occur when the LV is too underfilled and the VAD starts pulling in the septum or
00:48:30
Speaker
usually the septum, into the VAD itself and the VAD can't flow.
00:48:34
Speaker
So what does that mean?
00:48:35
Speaker
Well, it means you're usually going to get either a low flow alarm with the VAD itself and you may see power spikes along with it because it can't suck anything in, or can't suck a fluid in like blood.
00:48:47
Speaker
Or if it's a temporary VAD, you may notice that the cannula is coming out of the patient into the Centromag or chattering.
00:48:55
Speaker
And this is something very similar or analogous to chattering of an ECMO circuit.
00:49:00
Speaker
that's a pretty much a suction event and that means your left ventricle is under filled.
00:49:04
Speaker
So VAD flows in particular can change
00:49:11
Speaker
increase if the patient gets hypotensive though.
00:49:14
Speaker
So your vasopressor titration can affect the performance of your VAD in the sense that if the patient's afterload goes down, well all of a sudden the VAD's like, wow this is really easy, I can flow a lot more and empty out your LV.
00:49:28
Speaker
So again, highlights the importance of keeping that map range pretty tight.
00:49:34
Speaker
And then obviously other reasons that your LV can become small, whether or not it's tamponade, excessive chest wall swelling for loss of domain, RV failure.
00:49:43
Speaker
These can lead to an underfilled LV and suction events.
00:49:46
Speaker
So these should be taken quite seriously.
00:49:49
Speaker
I think most of the time your initial intervention for a suction event or a low flow related to a suction event is going to be a small fluid bolus to see if you can increase that preload and distend the LV a little bit more.
00:50:01
Speaker
But you may also decide to increase your MAP target and in some cases, let's just say you just need a little bit of time, you can even turn down the speed of the VAT itself.
00:50:13
Speaker
So the way I kind of approach these suction events is I bring my ultrasound to the bedside and if you're savvy with bedside ultrasound, it's a great tool to look at the left ventricle.
00:50:24
Speaker
It's not impossible to see the heart after cardiac surgery with a surface echocardiogram.
00:50:29
Speaker
So looking at the LV cavity size, if the cavity size is a one-to-one ratio with the size of that inflow cannula, that's a high-risk patient for suck-down.
00:50:42
Speaker
And then obviously you're going to do a couple other diagnostic tests to figure out why the LV is empty.
00:50:48
Speaker
So looking for low flow alarms with high power spikes, even things... Sorry, Sergio.
00:51:01
Speaker
Even a suckdown event can even cause tachydysrhythmias, particularly wide-complex tachycardias, VTAC, when the septum gets sucked into the VAD.
00:51:10
Speaker
Those are all complications of an underfilled LV in the setting of a fixed-speed VAD.
00:51:15
Speaker
And I think that, like you said from the beginning, it seems like a lot of our differential diagnosis really ultimately will pan out to what do I need to act on, my preload or my afterload, right?
00:51:28
Speaker
And the underfilled LV, like you said, could be because we need to increase the preload, or it could be because we need to decrease the afterload of the LV, or it might be a problem with the right ventricle.
00:51:38
Speaker
And all these things are going to come in recurrent.
00:51:41
Speaker
So I think that we need to be really always thinking about this as we intervene on these patients.
00:51:48
Speaker
No, totally.
00:51:49
Speaker
So suck down is a symptom.
00:51:51
Speaker
It is not a diagnosis.
00:51:53
Speaker
So suck down or a suction event is going to lead you to try and figure out what else is going on.
00:51:59
Speaker
Excellent.
00:51:59
Speaker
And you mentioned arrhythmias, which I presume are obviously very common in this population, but also something that can be exacerbated by all these foreign devices into the heart.
00:52:13
Speaker
Can you talk a little bit in general terms of what we should be concerned about with arrhythmias in the immediate post-operative period, John?
00:52:20
Speaker
Yeah, so common things being common.
00:52:22
Speaker
So atrial fibrillation, post-cardiac surgery, or post-VAD placement is common.
00:52:28
Speaker
I usually, and I think most, will consider early intervention on post-operative AFib in durable VAD patients, largely because they may be highly dependent on the atrial kick for forward flow.
00:52:41
Speaker
So we'll often initiate, start with a bolus dose of amiodarone to try and help
00:52:49
Speaker
get the patient back in the sinus rhythm, even a couple of boluses of amiodarine 150 milligrams IV, because obviously the loading dose is about five grams.
00:52:58
Speaker
It'll take you forever to get there.
00:53:01
Speaker
But if you're weaned off of your vasopressors and your inotropes, early institution of a beta blocker is also a common intervention in these patients.
00:53:10
Speaker
And a lot of times the atrial fibrillation goes away, but sometimes it doesn't.
00:53:15
Speaker
It can cause some hemodynamic or flow issues.
00:53:19
Speaker
Now ventricular arrhythmias are also fairly common and these can be caused by a number of different issues.
00:53:27
Speaker
So we mentioned kind of suck down itself and in the immediate post-operative phase it may be caused by the inflow cannula malposition.
00:53:35
Speaker
So again getting back to
00:53:37
Speaker
your post-operative echo.
00:53:39
Speaker
Suction events can cause irritation of the septum causing VTAC and the intervention for that is a simple fluid bolus.
00:53:45
Speaker
But also these patients are oftentimes have dilated cardiomyopathies so they're at high risk for VT just by the nature of their end-stage heart disease.
00:53:53
Speaker
So
00:53:55
Speaker
You know, if the one thing that's important, I would say that remember, if their ICD is still in place after they had their VAD placed, put a magnet on it so that they'd stop getting shocked.
00:54:07
Speaker
This is one thing that you can fix and address as you're starting your antiarrhythmics.
00:54:12
Speaker
The VAD is generally supported or the left ventricle is supported now with a mechanical device.
Arrhythmias and Emergency Protocols
00:54:17
Speaker
So it's not like a native heart VTAC.
00:54:19
Speaker
You have a little bit of time.
00:54:21
Speaker
A little bit of time.
00:54:23
Speaker
Now, if the patient remains in VT for a long period of time, this can cause you some hemodynamic issues.
00:54:29
Speaker
But as you're giving some medicines, it's okay to turn off or put a magnet on that ICD for a short period of time while you're trying to make some interventions.
00:54:38
Speaker
And as I mentioned, similar to the AFib,
00:54:41
Speaker
Beta blockers, amiodarone, and lidocaine are usually considered first-line medications in these acute postoperative and even some of the long-term durable VAD patients.
00:54:55
Speaker
So we talked about a whole set of common complications.
00:54:59
Speaker
Like we were talking before we started recording the podcast, the list of complications is very long and a lot of that will be referred to in some of the links in the show notes.
00:55:08
Speaker
But what I wanted to go next, John, is to
00:55:12
Speaker
To think about from the standpoint of addressing a patient who's unstable or let's call it a crashing bad patient, there's clearly two tools that I think are very useful in the immediate assessment.
00:55:25
Speaker
And one of them is understanding the control box alarms or what's changed.
00:55:30
Speaker
And the other one is the use of echo.
00:55:32
Speaker
Can you walk us through those two in the setting of somebody who has changed a status or is, quote unquote, unstable or crashing?
00:55:40
Speaker
Yeah.
00:55:42
Speaker
Yeah, so bedside ultrasound is absolutely your best friend.
00:55:47
Speaker
And so if there's a patient who's really doing unwell, the ultrasound is the first thing I'm bringing to the bedside.
00:55:54
Speaker
And in the immediate post-operative setting, so we're talking about within the first 12 to 24 or even 48 hours, if a patient is crashing in front of me, I'm looking for a tamponade, looking for all the complications we mentioned before.
00:56:06
Speaker
But if
00:56:08
Speaker
If their map starts to drop and we're maxed out on pressers and we're still at a map of less than 40 and I'm concerned that they're not perfusing, I'm calling cardiac surgery to bedside to do basically a bedside sternotomy so to open the patient back up.
00:56:25
Speaker
Oftentimes this is not a time to continue to provide excess amount of vasopressors.
00:56:31
Speaker
It's usually a surgical issue and that needs to be addressed either in the OR or even in some cases at the bedside, not a medical management point.
00:56:40
Speaker
So taking a look to see if there's any fluid around the heart or if the RV is bowing out are things that are going to be really helpful on bedside ultrasound.
00:56:50
Speaker
And I think in general, you know, one of the sort of algorithms that we follow is using that MAPA-40 as kind of your threshold to start thinking about is the patient perfusing anything at all?
00:57:04
Speaker
So post-operative stroke is a, I mean, it's just a killer for these patients who have a VAD.
00:57:11
Speaker
And particularly if they're destination, what's the point if they don't have a neurostatus or if they end up coming out with a stroke?
00:57:19
Speaker
You've just put a $100,000 device in someone who's not going to be able to use it to its full effect.
00:57:24
Speaker
So really staying on top of this and in the crashing patient, you know, thinking about early reopening is really, really important.
00:57:33
Speaker
But let's just say that, you know, it's not in the immediate postoperative phase.
00:57:39
Speaker
Maybe this person came in through the emergency department.
00:57:42
Speaker
I think one question often is, is it okay to do CPR on these patients?
00:57:46
Speaker
And so, you know, what I usually say, or at least how I educate my emergency physicians about this is, okay, you treat this patient almost like a tracheotomy patient, a tracheostomy patient, right?
00:57:59
Speaker
So, you know, in the tracheostomy patient, they come in respiratory failure.
00:58:04
Speaker
They still have a set of lungs.
00:58:06
Speaker
And they still have a trachea.
00:58:07
Speaker
So if the trach's not working, intubate them.
00:58:09
Speaker
Use their native lungs.
00:58:10
Speaker
Well, in the case of a VAD patient, if the VAD patient's crashing and hemodynamically unstable, they still have a native
CPR and VAD Patients: Myths and Facts
00:58:17
Speaker
heart.
00:58:17
Speaker
So use it.
00:58:18
Speaker
Early initiation of inotropes, epinephrine to try and maximize their native cardiac performance is going to be what you're going to try to do right off the bat.
00:58:27
Speaker
And oftentimes this just involves a small fluid challenge followed by vasopressors and inotropes.
00:58:34
Speaker
And while you're waiting to get in contact with the VAD team,
00:58:37
Speaker
Now if you do that, and even after about one minute, if there's still minimal flow, and this can be assessed by Doppler if you don't have an A-line in place, so a bedside Doppler in the brachial artery is the usual recommended place to listen for actual flow.
00:58:55
Speaker
If there's minimal flow and the patient's MAP is less than 40, go ahead and start CPR.
00:59:02
Speaker
There used to be a large myth that was put out that you cannot perform CPR on patients with a VAD, and that's just not true.
00:59:13
Speaker
There are a few small case series that looked at post-mortem patients who died after who also had a VAD.
00:59:21
Speaker
and who received CPR, and not a single one of them had a VAD dislodgement.
00:59:26
Speaker
Now, certainly, it's going to be something you're going to worry about if you have to do CPR, but it's not a contraindication.
00:59:34
Speaker
So for your ER providers, it is absolutely okay to do CPR.
00:59:39
Speaker
We do it in our ICU as well.
00:59:41
Speaker
You want to protect the brain if you're trying to get this patient out of this acute event.
00:59:45
Speaker
So establishing some form of flow is better than no flow at all.
00:59:50
Speaker
And what about understanding what changes like in flow and power or in the PI might mean in terms of potential diagnosis?
00:59:59
Speaker
Can you talk a little bit about that, John?
01:00:02
Speaker
Yeah, sure.
01:00:03
Speaker
So I do have my own like internal algorithm on how to approach this differential diagnosis.
01:00:09
Speaker
And in the show notes, there'll be a little, a fairly simple algorithm on different alarms that you might get at the bedside.
01:00:17
Speaker
So yeah,
01:00:19
Speaker
To go through particularly, I think probably flow alarms are the most common and most important.
01:00:25
Speaker
So with low flow alarms, you're going to think of a couple of different things.
01:00:29
Speaker
So low flow can be caused by obviously hypovolemia, which we talked about a little bit with LV size.
01:00:36
Speaker
Don't forget, hypovolemia may also include hemorrhage as well.
01:00:41
Speaker
So an unrecognized GI bleed is something that I've gotten fooled on before, will also cause a hypovolemic state, obviously, and low flow alarms.
01:00:52
Speaker
Arrhythmias and inflow-outflow cannula obstruction will also often cause low flow alarms.
01:00:59
Speaker
And then obviously your right ventricular failure and tamponade in the immediate postoperative phase is something you're always going to be concerned about.
01:01:06
Speaker
Now, the flip side of that are your high flow alarms.
01:01:09
Speaker
So this means all of a sudden the VAD is still at the same set speed, but the flows are going up.
01:01:15
Speaker
And you may see this like it.
01:01:17
Speaker
So, for example, on your HeartMate 2s, oftentimes a high flow is it won't even show the leader's permit anymore.
01:01:24
Speaker
The monitor will actually have three plus signs, which means it's
01:01:28
Speaker
it thinks it's flowing a lot.
01:01:31
Speaker
It may not be, but it thinks it is.
01:01:32
Speaker
And if you see this, you're going to want to be concerned of a vasoplegic state.
01:01:37
Speaker
So that might be from something like sepsis or
01:01:41
Speaker
something even more insidious and concerning, which would be a rotor thrombus or a VAD thrombus.
01:01:48
Speaker
And the reason why you get high flow alarms here is largely because, remember what I said in terms of the VAD flows are not actual flows.
01:01:58
Speaker
It's not like it's doing a thermodilution like a PA catheter or something like that.
01:02:03
Speaker
It's estimated or calculated based on the power and the speed in which it's set.
01:02:08
Speaker
So if all of a sudden the VAD feels like it's working really, really hard to achieve that speed that it's set for, and that could be because there's a big clot jammed in the rotor, that'll give you high flow alarms.
01:02:22
Speaker
So high flow alarms or low flow alarms could mean a VAD thrombus and worth further investigation.
01:02:30
Speaker
Now if you want to move over just quickly to pulsatility, so remember it's like kind of the contribution of the native heart, the contractility of the blood moving through the VAD as opposed to whether or not it's just straight continuous flow.
01:02:43
Speaker
Things that can give you high pulsatility, I think the most common thing we see is hypertension.
01:02:48
Speaker
So if all of a sudden the afterload on that VAD is really high, it's going to make the LV distend a little bit more because less blood's going through the VAD.
01:02:56
Speaker
So the heart's going to become more contractile.
01:02:59
Speaker
You're going to have a high pulsatility as a result of that.
01:03:03
Speaker
In the outpatient world, you may see as a patient who's a bridge to recovery as their heart gets better, well, that means it's going to contract more.
01:03:10
Speaker
So you're going to see high pulsatility, and sometimes some electrical malfunctions can cause high pulsatility alarms.
01:03:18
Speaker
And then to the opposite side, low pulsatility.
01:03:22
Speaker
Getting back to kind of your low flow, so hypovolemia, poor LV function, recent changes in speed.
01:03:28
Speaker
So they might have been at their outpatient and got their speed changed recently.
01:03:32
Speaker
That's now overflowed their left ventricle, so now it's more empty.
01:03:39
Speaker
That can cause low pulsatility.
01:03:42
Speaker
And then, again, your inflow-outflow obstructions as well.
01:03:46
Speaker
Well, John, this has been a fascinating conversation.
01:03:49
Speaker
I think that, like we mentioned at the beginning, a growing population in our healthcare, something that I think more frequently our intensivists are being exposed, especially, I mean, in places that are doing a lot of heart transplant and heart failure, but also in ICUs that might use these as temporary bridges for transfer to a higher acuity setting or for recovery.
01:04:13
Speaker
In previous episodes, you're a seasoned guest.
01:04:17
Speaker
We usually close with some questions unrelated to the topic.
01:04:21
Speaker
You've been through those.
01:04:22
Speaker
So today I'm going to ask you a couple of questions that are similar but are more related to the topic that we spoke today.
01:04:27
Speaker
Is that okay?
01:04:29
Speaker
That sounds great.
01:04:30
Speaker
These are the hardest ones.
01:04:31
Speaker
So my first question is, could you tell us about your most instructive failure with dealing with these patients?
01:04:38
Speaker
I think that one of the things that we don't value as much as we should is
01:04:43
Speaker
the ability to learn from failure and embrace failure as an opportunity.
01:04:47
Speaker
So could you tell me your biggest fail with these patients?
01:04:51
Speaker
Yeah, so the biggest one's tough because I've definitely had my fair share of learning lessons, if you will, from taking care of these the VAD patients.
01:05:03
Speaker
You know, I think starting out as a fellow
01:05:07
Speaker
There was one patient in particular that always stuck with me.
01:05:12
Speaker
And, you know, I think the immediate post-operative patients, oftentimes you kind of know what to look out for.
01:05:17
Speaker
But in the outpatient world, you know, all bets are off.
01:05:21
Speaker
They could come in with sepsis or anything.
01:05:24
Speaker
And oftentimes people freak out just because there's a VAD patient in the emergency department or in the hospital and they don't take care of VAD patients.
01:05:33
Speaker
So, yeah.
01:05:35
Speaker
there was an elderly gentleman, his name was Frank.
01:05:38
Speaker
He was in his late 60s and was a destination therapy patient.
01:05:44
Speaker
And he was destination because his grandkids, one of his grandkids was graduating college and he really wanted to make it to the graduation.
01:05:55
Speaker
And, you know, we're very familiar with that patients getting, you know,
01:05:59
Speaker
dehydrated, nausea, vomiting, diarrhea, causing some problems with the flow alarms.
01:06:05
Speaker
And he came in kind of with a very nondescript syndrome of, like his wife said, he was just feeling weak and he was having some nausea, vomiting, and some GI symptoms, which was probably more related to poor flow.
01:06:20
Speaker
But I started just kind of treating him with, he was a little bit hypotensive, so we gave him some fluids.
01:06:25
Speaker
And then all of a sudden, his hemodynamics just crashed.
01:06:30
Speaker
it wasn't until about 30 minutes later that he finally had his first bowel movement and it was just a massive GI bleed.
01:06:37
Speaker
And I really was kicking myself and I knew you know AVMs are a common complication with VAD patients but it didn't hit me right off the bat that that's probably what was going on.
01:06:48
Speaker
He was getting fluid and he should have been getting blood and I should have reversed his anticoagulation and unfortunately you know he ended up doing okay but had a rocky course.
01:06:57
Speaker
So you know
01:06:59
Speaker
Sometimes out of sight, out of mind, we're not thinking about things like GI bleeds with patients who hasn't had a frank hematemesis or bloody bowel movement.
01:07:08
Speaker
So that's one thing that stuck with me.
01:07:10
Speaker
Always never forget about these bleeding complications.
01:07:13
Speaker
They're the most common and sometimes the hardest to diagnose.
01:07:17
Speaker
I think that's a great point.
01:07:18
Speaker
Like you mentioned earlier, a quarter of these patients will have bleeding complications.
01:07:23
Speaker
And just think of common things as possible causes.
01:07:27
Speaker
The second question I have, John, relates to something that now that you have so much experience with these patients that you know to be true, yet most intensivists who don't deal with these patients on a regular basis get wrong about this patient population.
01:07:45
Speaker
So it's a great question.
01:07:48
Speaker
And I think that sometimes when we deal with patients that are so sick all the time, we develop this, not nihilism, but this kind of thought of, yeah, this patient's not going to get better.
01:08:00
Speaker
They need a freaking machine to keep their heart going.
01:08:05
Speaker
In some cases, I think the cardiac surgery intensivist stretches into the realm of the oncologist intensivist that deal with end-stage disease, and we think they're not going to get better.
01:08:20
Speaker
But I definitely want to press the audience here that that's not true.
01:08:27
Speaker
these patients in particular went through a lot to become eligible to get their VAD.
01:08:32
Speaker
And there is such a rigorous screening process that goes from social to physiologic to optimizing them, leading them in.
01:08:42
Speaker
They, in some cases, wait for years to get their VAD on home infusions.
01:08:47
Speaker
So they put a lot of work into getting to this point where they can get off their continuous medications at home, infusions, that sort of thing.
01:08:56
Speaker
And these patients can turn around.
01:08:58
Speaker
And I think it's worth at least a time-limited trial to try and get these patients better and out of the ICU.
01:09:06
Speaker
Now, certainly, we're going to be realistic and optimistic with the family with destination patients.
01:09:11
Speaker
But for those bridge-to-transplant patients and bridge-to-recovery patients,
01:09:16
Speaker
there is opportunity to salvage these patients, so don't give up on them.
01:09:20
Speaker
Definitely work within the multidisciplinary culture in your ICU.
01:09:25
Speaker
Get everyone on board, and if that means transfer, get them to transfer.
01:09:29
Speaker
And in some cases, if it is available to you and the patient is crashing, it's not unreasonable to put the patient on a temporary ECMO support to get them to
01:09:40
Speaker
to another institution, there have been a couple of bad thrombosis patients that have recovered amazingly after getting a VAD explant implant that might have just been due to some unintended complication
Encouragement and Recovery Potential for VAD Patients
01:09:56
Speaker
as an outpatient.
01:09:56
Speaker
But these patients can recover, so I don't want you to give up on them early on.
01:10:00
Speaker
These are definitely salvageable patients.
01:10:02
Speaker
And I think that along those lines, an area that I think in my own practice, I'm trying to be more positive
01:10:10
Speaker
open-minded and objective about is those patients who crash and are bridges to decision because it might not be clear, but we don't know for a fact that they won't be able to recover, that they wouldn't be a good candidate for destination therapy or a transplant.
01:10:25
Speaker
And I think that really, like you said, understanding that a lot of these patients do have meaningful recovery.
01:10:32
Speaker
and can have a prolonged quality of life afterwards, it's something that we need to really understand in the ICU.
01:10:39
Speaker
And I think it's difficult when we don't see these patients long term.
01:10:45
Speaker
Yeah, 100% agree.
01:10:47
Speaker
The VAD teams kind of grow with these patients, and they're much more familiar with them.
01:10:52
Speaker
then we might be in just this episodic care of this patient.
01:10:55
Speaker
But it's such a great point, Sergio, is that, you know, keeping a frame of reference in terms of what the patient's goals are and where we work within the trajectory of the patient care.
01:11:07
Speaker
Absolutely.
01:11:08
Speaker
And the final question to close, John, is what do you want every listener to our podcast to know specifically about this topic, the single most important take-home message?
01:11:21
Speaker
Yeah, this is a tough one.
01:11:23
Speaker
Yeah, the single most important topic, you know,
01:11:29
Speaker
I think that you have options, that this isn't an end game.
01:11:33
Speaker
The VAD itself isn't an end game.
01:11:36
Speaker
We kind of touched on not giving up, but I think keeping your eyes wide open in terms of what the goal is for the patient, I think we've all moved towards keeping
01:11:51
Speaker
patient goals in mind and trying to honor those patient wishes as much as we possibly can.
01:11:58
Speaker
So I think the last question brought up, don't giving up on these patients.
01:12:01
Speaker
I think that's probably the most important thing.
01:12:04
Speaker
And just be thoughtful about the things you're trying to accomplish.
01:12:07
Speaker
Be honest with the families, engage them early, and then obviously
01:12:12
Speaker
keeping their heart failure cardiologist and VAD coordinating team together, creating a multidisciplinary approach to manage these really complex patients is probably the most important thing when it comes to taking care of the VAD patient.
01:12:29
Speaker
Well, I want to be respectful of your time, but again, John, thank you, thank you for your time, generosity with all your knowledge, for preparing an excellent handout for our listeners, and for really a fascinating discussion on a topic that I think we're going to see more and more.
01:12:44
Speaker
So I hope to have you back on the show soon, and thank you very much.
01:12:49
Speaker
Oh, absolutely, Sergio.
01:12:50
Speaker
This is an honor.
01:12:51
Speaker
You have developed quite a following so far, so this is exciting to be a part of.
01:12:58
Speaker
Thanks again for listening to Critical Matters.
01:13:00
Speaker
Make sure to subscribe to this podcast on iTunes or Google Play.