Impella

[VFlutter]

We have been seeing an increase in Impella transfers lately so I figured I would throw something together and share some info on them. Just like how IABPs have proliferated Impella’s are now becoming more popular due to their relative ease of insertion and ability to stabilize patients in extremis. However many facilities that have the ability to place Imeplla’s in the Cath Lab do not have the necessary ICU/CCU support to manage them or the CT surgery to bride to another device which necessitates transfer to tertiary facilities.



First thing I would recommend is to download the Impella app by Abiomed. Tons of great info.



Impella is an Axial Flow Percutaneous Left Ventricular Assist Device (PLVAD) and more recently a Percutaneous Right Ventricular Assist Device (PRVAD). The LVAD comes in a few different models with varying range of flow rates and sheath sizes. The 2.5 (2.5L Flow) and CP (3.5L Flow) are the most common as they only require 6-9fr sheaths which can be placed peripherally in the femoral artery. The 5.0 (5.0L flow) and LD (5.0+L flow) are inserted via 21fr sheaths and are usually inserted via an Axillary Artery Cutdown or centrally via a sternotomy. Transport of a 5.0/CP should be rare since most hospital which placed them are tertiary facilities however if they need to transplant they may be transported to a transplant center.



The Imeplla RP is inserted via the Femoral Vein and provides up to 4.5L of flow.

It is possible to have both an Impella RVAD and LVAD simultaneously for biventricular support.


Indications:

1) Cardiogenic Shock (Temporary or Bridge to LVAD/ECMO)

2) Cardiac support during high risk PCI

3) Adjunct to VA ECMO to vent the LV and prevent LV distention/Thrombus

Contradictions:

1) Aortic disease

2) Aortic Valve disease

3) LA/LV thrombus

4) Severe bleeding or sepsis

Complications:

1) Limb ischemia

2) Aortic valve damage

3) Hemolysis/bleeding

4) Vessel damage



Impella vs IABP. Impella is true mechanical circulatory support but does not increase coronary perfusion where as an IABP increases coronary perfusion but does relatively little for circulatory support. Studies show little difference in mortality in Acute MI. Impella is better suited for cardiogenic shock without current ischemia (Post PCI, Non-ischemic CHF, etc) however for patients whom still have ischemia (Still need CABG, Poor flow after PCI) an IABP may be better.



If you are transporting these patients I am assuming you have done the Impella training online so I will not go into the various placement and motor current signals however just remember that the 2.5/CP and 5.0/LD have different ways of detecting placement, Open pressure port vs differential pressure. Again, reference the Impella App for examples.



Patient management:



Same as any other device make sure you document insertion depth and assessment of insertion site. Make sure there are no hematomas or active bleed. Make sure the catheter is secured. Assess peripheral pulses as limb ischemia is a big concern. Keep head of bed the same since flexion/extension of the upper body may cause the catheter to dislodge. The device should have a pressure bag for the arterial line and a bag of purge fluid that is Dextrose (D5-D20) with Heparin.



Like any other LVAD the Impella relies on preload so make sure fluid status is adequate. If patient is in RV failure you may need to aggressively treat with Inotropes or pacing if fluid bolus are not enough to maintain preload. If they have a Swan I would have a NS drip with pressure bag placed to the Cordis or RV/Pacer port (Orange) so you can bolus if needed. Titrate pressor to maintain perfusion however remember SBP = SVR so don’t go crazy.



Patients who have poor native heart function may go non-pulsatile at times. Assess placement signals, Flow, and motor current and make sure the Impella is not out of position. The motor current and flow should stay normal. Assess for shock, get a MAP. Remember that normal Cardiac Output is 4-8L whereas the Impella is only providing 2.5L without native function. Treat ventricular arrhythmias if needed.



If Impella alarms suction event then reduce power level and give fluid. If it alarms placement signal then reduce power level to P2 and treat patient medically. They actually dislodge fairly easily (out of the ventricle, not the patient) Call receiving and let them know they will need to reposition on arrival. If it alarms about purge flow make sure the purge line is not kinked or has air bubbles. Re-prime if needed.


That is pretty much the basics. Feel free to add your experiences or ask questions.

 

[BMedic]

About 3 months ago some local hospitals asked our agency to go over impella training for all crew members.

 

[VFlutter]

Scenario. You respond for a patient s/p STEMI and cardiac arrest with an Impella CP.

You arrive in your patient's room and see this..... And go

 

[E tank]

OK, I'll bite...guy's unconscious, right? Not breathing? Doesn't look like the heart is beating from your screen shot so....lemme think....CPR! I think you're supposed to turn the flow on the device down, but depending on the flow capacity on the device, not sure how much that matters. I don't take care of these patients if I can avoid it...

 

[VFlutter]

OK, I'll bite...guy's unconscious, right? Not breathing? Doesn't look like the heart is beating from your screen shot so....lemme think....CPR! I think you're supposed to turn the flow on the device down, but depending on the flow capacity on the device, not sure how much that matters. I don't take care of these patients if I can avoid it...

Patient is intubated and on the ventilator. The patient does not have a palpable pulse and his Arterial Line (The impella placement signal is not a true arterial waveform) is showing a similar non-pusatile waveform.

You are correct that his heart is not producing cardiac output. He happens to be in sustained VT after multiple Defibrillations.

Is CPR indicated? Is there any perfusion? What type of device is an Impella.

 

[Summit]

I was trained on Impella several years ago but never actually saw an impella patient so I don't remember very much and the following might be WAY off base... but I've never been shy about guessing and being wrong in a learning environment... so here's a try.

Axial flow pumps won't generate pulsatile waveforms even though they provide forward flow (up to 4.5L CO in this CP case).

So you might have enough perfusion to temporize especially if you manage your SVR with vasoactives. And let's either go to BVM or set the vent to the lowest PEEP setting to promote venous return and pulmonary circuit perfusion.

Temporizing to allow you to solve the VT... but I don't think you can temporize long (and multipel defib cycles might mean you are at the end of that short window, but it depends on the patient). So if you don't have a good reason as to why there is VT resistant to defib (eg electrolyte problem is it torsades?) that you can't rapidly address (like with a mag push) then you will need to do CPR because this guy doesn't have an impella on the right side either (VT is providing the only forward flow in the pulmonary circuit). So you are looking at CPR to cath lab it was an a thromboembolic STEMI (which you shouldn't have because they are systemically anticoagulated for Impella) or a planned trip to EP lab for ablation... then you are in a bad place... also CPR is known to displace Impella so better have echo ready to check... but I think this case could have a crap prognosis. Is the CT surgeon on the way so you can cannulate for ECMO.

Curious how far off I am...

 

[E tank]

Patient is intubated and on the ventilator. The patient does not have a palpable pulse and his Arterial Line (The impella placement signal is not a true arterial waveform) is showing a similar non-pusatile waveform.

You are correct that his heart is not producing cardiac output. He happens to be in sustained VT after multiple Defibrillations.

Is CPR indicated? Is there any perfusion? What type of device is an Impella.

No personal experience here with the Impella, and I won't insult you with google-ing answers for a contrived internet conversation, so you truly are educating me here... Depending on the device, as I understand, different flows are possible. So while your screen shot shows what I assume is a mean arterial pressure in the mid 70's, which is pretty good, that does not imply that there is an adequate CO. And where is that pressure being measured? The LV? Ascending aorta? Radial artery? Makes a big difference.

Further, it isn't ecmo, but the ventilator is seeing to oxygenation/ventilation, assuming that there is sufficient cardiac output, to say nothing of the brain or kidneys...

 

[VFlutter]

I was trained on Impella several years ago but never actually saw an impella patient so I don't remember very much and the following might be WAY off base... but I've never been shy about guessing and being wrong in a learning environment... so here's a try.

Axial flow pumps won't generate pulsatile waveforms even though they provide forward flow (up to 4.5L CO in this CP case).

So you might have enough perfusion to temporize especially if you manage your SVR with vasoactives. And let's either go to BVM or set the vent to the lowest PEEP setting to promote venous return and pulmonary circuit perfusion.

Temporizing to allow you to solve the VT... but I don't think you can temporize long (and multipel defib cycles might mean you are at the end of that short window, but it depends on the patient). So if you don't have a good reason as to why there is VT resistant to defib (eg electrolyte problem is it torsades?) that you can't rapidly address (like with a mag push) then you will need to do CPR because this guy doesn't have an impella on the right side either (VT is providing the only forward flow in the pulmonary circuit). So you are looking at CPR to cath lab it was an a thromboembolic STEMI (which you shouldn't have because they are systemically anticoagulated for Impella) or a planned trip to EP lab for ablation... then you are in a bad place... also CPR is known to displace Impella so better have echo ready to check... but I think this case could have a crap prognosis. Is the CT surgeon on the way so you can cannulate for ECMO.

Curious how far off I am...

Pretty much got it. It is an axial flow device with continuous non-pulsatile flow however is designed to function with some intrinsic cardiac function as opposed to a complete support device like ECMO. Without any intrinsic cardiac output the CP will flow 3.0-3.5 Lpm. So enough flow for some perfusion but inadequate long term. non-pulsatile flow also isn't ideal for certain organ perfusion and oxygenation.

As you pointed out the big problem with sustained VT is RV dysfunction and loss of preload to the LV and Impella. All VADs are very much preload dependent and without lead to low flow, suck down, and possible thrombus.

Patient's Left Main was ballooned in the CCL but no stent. Refractory VT was probably due to reoccluson. of his LM.

No personal experience here with the Impella, and I won't insult you with google-ing answers for a contrived internet conversation, so you truly are educating me here... Depending on the device, as I understand, different flows are possible. So while your screen shot shows what I assume is a mean arterial pressure in the mid 70's, which is pretty good, that does not imply that there is an adequate CO. And where is that pressure being measured? The LV? Ascending aorta? Radial artery? Makes a big difference.

Further, it isn't ecmo, but the ventilator is seeing to oxygenation/ventilation, assuming that there is sufficient cardiac output, to say nothing of the brain or kidneys...

å

The Impella placement signal is a differential pressure from the outlet in the proximal Ascending Aorta and is usually pretty close to a true arterial pressure. Radial Arterial line was reading MAPs in the mid/low 60s.

Correct. Oxygenation was a huge issues. 3L of flow isn't much for tissues oxygenation. From my understanding there is a significant drop in efficiency of oxygenation in the lungs and cerebral oxygenation with non-pulsatile vs pulsatile flow. Not a huge issue with ECMO since gas exchange occurs externally in the oxygenator. Also why you sometimes see CT surgeons place IABP with ECMO to produce pulsation.

 

[TXmed]

Also why you sometimes see CT surgeons place IABP with ECMO to produce pulsation.

This makes alot of sense, thank you for clerifying this. I was told that they place the IABP in ECMO to reduce the instance of cardiac stunning. And i always wondered why they went with a balloon instead of an impella, but now i know.

 

[VFlutter]

This makes alot of sense, thank you for clerifying this. I was told that they place the IABP in ECMO to reduce the instance of cardiac stunning. And i always wondered why they went with a balloon instead of an impella, but now i know.

Peripheral VA ECMO can actually worsen or stun intrinsic cardiac function due to the increase in afterload caused by retrograde flow. The Arterial cannula in the Femoral Artery flows backward to the Aorta and Heart and can cause the LV to distended and worsens cardiac function (Starling). Also can lead to LV thrombus. Some Surgeons prefer an Impella to "vent" the LV. Others will use an IABP. The thought being the addition of pulsation limits the negative effects of VA ECMO and improves coronary perfusion.This isn't a problem with centrally cannulated ECMO.