46 Impella

Impella microaxial flow pumps are placed fluoroscopically in retrograde fashion through the femoral artery, axillary artery, or ascending aorta
Blood 🩸 is suctioned from an inlet (located just superior to the catheter’s pigtail in the LV cavity) and then delivered through the Impella outlet, which is seated just above the aortic valve.
The distal portion of the Impella is a pigtail configuration that is meant to reside in the mid LV approximately ==3.5 cm below the aortic annulus==.
Uses: high-risk PCI, post-MI shock, ADHF, post-cardiotomy shock, etc.
Complications
- hemolysis
- pigment-induced nephropathy
- vascular access complications, e.g. limb ischemia, major bleeding
- pericardial tamponade
- MV impingement w/ mitral regurgitation
- thrombosis → device failure
Two main ways it helps:
- unloading (↓ EDV and EDV) and
- outflow (↑ flow)
Unloads the LV by continuously drawing blood from LV
- ↓ LV work and myocardial O₂ demand
- ↑ MAP and CO
- Improved systemic perfusion and coronary blood flow
- ↓ PCWP
- Reduction in RV afterload
5.5 is bigger and runs at lower rpm; less hemolysis than 3.5 or CP

Note

“BiPELLA”: combination of LV and RV Impella support devices

CP - Catheter diameter is 9 Fr, 14 Fr pump motor
- 14 Fr sheath
- Peak flows up to 4.3 L/min
- Advantages
  - Quick Percutaneous placement
  - Axillary or femoral
- Disadvantages
  - Expensive ($25k)
  - Higher vascular complications
  - Can move with femoral placement
  - More hemolysis and thrombocytopenia
  - Difficulty mobilizing
5.5 - catheter diameter is 9 Fr, 19 Fr pump motor
- 21 Fr cannula in 10mm Hemashield graft
- Peak flows up to 6.0 L/min (even though its called “5.5”)
- Advantages
  - Stable positioning
  - Good flows
  - No pigtail
  - Patient can mobilize
- Disadvantages
  - Expensive ($45k)
    - Surgical placement and removal
Purge solution is used through the impella catheter
- One or the other - NOT used together
  - D5W with 25 or 50 IU/ml Heparin
  - D5W with 25 or 50 mEq/L Sodium Bicarbonate
    - especially if indication not to use heparin
Inlet should be approximately 5cm into the LV

46.1 Indications

Goals
- MAP 60-80
- CVP 8-15
- PCWP ≥ 10
- Cardiac Power Output > 0.6
Distance from aortic valve to Impella inlet
- Impella CP: 3.5 cm from valve to inlet
- Impella 5.5: 5 cm from valve to inlet
Calculate PAPI if CVP > 16

Check to make sure that the Tuohy-Borst valves are locked
Record the centimeter mark on the cather (record at the mark closest to the Tuohy-Borst valve)
Check volume status and ensure adequate
Obtain a baseline echo upon arrival to the ICU (or if suspected catheter movement)
Check Foley bag for urine color (signs of hemolysis?) and amount

Ensure slack was removed after positioning the inlet area - 3.5 cm for Impella CP and 5 cm for Impella 5.5 - below the aortic valve annulus.
Ensure the Tuohy-Borst is tight and note the centimeter mark on the cather.
Immobilize the leg if the patient is overactive or uncooperative
Obtain a baseline echo upon arrival to the ICU (or if suspected catheter movement)
Address positioning alarms
If you do have to move the catheter to reposition, turn down to P-2

Impella in Ventricle
- Appearance on monitor: flat motor current + ventricular placement signal
Impella in Atrium
- Appearance on monitor: flat motor current + atrial placement signal

Reduce to P2
Under echo guidance, reposition to 3.5 cm below the AV.
If fails, then will need to go to the cath lab for repositioning under fluoro guidance

	CVP ≤ 12	CVP > 12
Persistent Suction Alarm	Low volume status	Strongly consider Right ❤️ Support
No Persistent Suction Alarm	No action	High volume status

In both scenarious (continuous or diastolic suction alarms), check RV function using PAPI (PA pulsatility index) or Echo.

\[ \text{PAPI} = \frac{\text{PA}_{\text{systolic}} - \text{PA}_{\text{diastolic}}}{\text{RA pressure}} \]

Important

Check right heart function if persistent suction alarms despite good volume status and correct Impella position.

The systolic LV numbers (in white) are uncoupled from the aortic numbers (shown in red). You will see low systolic pressures and negative diastolic pressures that don’t recover (unlike with diastolic suction problems).
- The entire LV waveform shifts downward
The diastolic LV numbers are also quite negative
Max and Min Impella flows are lower than expected

The LV waveform (in white) will have normal systolic pressures, but negative diastolic pressures that recover by the end of diastole
There will be low diastolic Impella Flow

High purge pressure?
- Look for kinks in tubing
- Can ↓ dextrose in purge solution
Low purge pressure?
- Check for leaks
- Can ↑ dextrose in purge solution

Warning

If butterfly is flat against the skin, use 4x4s to angle match and reduce lift on vessel (See Figure 46.1)

Dr. Hart also mentioned that the following figure 8 suturing technique may be useful to help with access site bleeding (oozing) (n.d.)

Warning

You should suspect hemolysis if the urine color is red!

Potential obstruction at different levels
- Inflow obstruction
- Cannula obstruction
- Outflow obstruction
Rule out blood in urine
- Check a UA (fastest)
- Check plasma free Hemoglobin
- Check spun plasma color if plasma free Hemoglobin is unavailable
- Check LDH
Consider giving volume if hemolysis + CVP or PCWP < 10 mmHg
Assess the position of the Impella using Echo
- Unobstructed inflow
- Approx. 3.5 cm distal to the aortic valve
- Free from anterior mitral leaflet
- Free from sub-annular structures
- Outflow well above the aortic valve
- Stable position that does not migrate
- Reduce flow as tolerated
- Pump removal if needed