Impella Waveforms, Positioning, and Repositioning
Best Practices for Patients Supported with Impella® (Part 2)
“Position assessment is very important every day,” Dr. Behnam Tehrani emphasizes in this discussion of Impella waveforms, positioning, and repositioning best practices. When Impella is correctly positioned, the inlet area of the device is about 3.5 centimeters below the aortic valve and the outlet area is in the aorta.
Dr. Tehrani explains that a key element of ensuring proper Impella positioning is having 3 people at the bedside in the CCU: 2 people for patient care and hygiene and 1 person dedicated to watching the waveforms on the Impella console and ensuring that the centimeter position on the catheter doesn’t change as the patient is moved.
Waveforms. “Understanding the waveforms is really important,” states Dr. Tehrani. He explains that the red placement signal waveform on the Impella console “displays a pressure measurement that is very useful and helpful in determining the location of the open pressure area of the catheter with respect to the aortic valve” and that the green motor current waveform “is essentially a measure of the energy intake of the Impella catheter and so it varies with speed and the pressure difference between the inlet and outlet areas of the cannula.”
What do the waveforms look like for different Impella positions?
- Correctly positioned Impella: Aortic placement signal waveform and pulsatile motor current waveform
- Impella too far into the ventricle: Ventricular placement signal waveform and dampened motor current waveform
- Impella too far out of the ventricle: Aortic placement signal waveform and dampened motor current waveform
The Impella console also displays alarms at the top of the display if Impella is not correctly positioned.
Position Assessment. Dr. Tehrani emphasizes the need for assessing Impella position daily and documenting position to prevent device migration and potential problems. If, for example, Impella is sitting on the anterior mitral valve leaflet, it may cause functional mitral stenosis, mitral regurgitation, or hemolysis. It may also lead to problems if it is abutting the posterior medial papillary muscle or entangled under subvalvular apparatus.
Repositioning. Dr. Tehrani offers the following best practices for repositioning Impella:
- “Always do it under imaging guidance.” Use fluoroscopic guidance when repositioning in the cath lab and echo guidance (parasternal long axis TTE or long axis TEE) in the CCU
- Reduce P-level to P2 when repositioning Impella
- Ensure that the inlet is ~3.5 cm below aortic valve
- Ensure that the catheter is not abutting the anterior mitral valve leaflet, subvalvular apparatus, or papillary muscles
- Remove all slack to prevent inward migration
- Lock down the Tuohy to help prevent device migration
- After repositioning, resume prior P-level setting and reassess final position with imaging
Dr. Tehrani also emphasizes the importance of PA catheter placement. “Never have a patient come upstairs from the cath lab without at PA catheter,” he states. “It’s really important as part of your weaning or escalation strategies to make sure a PA catheter is in place.”
Videos in this series:
- Part 1: Overview and Initial Management Tips
- Part 2: Impella Waveforms, Positioning, and Repositioning (current page)
- Part 3: Dr. Behnam Tehrani Discusses Hemolysis
- Part 4: Addressing Impella Alarms
- Part 5: Impella Groin Management
- Part 6: Impella Weaning and Escalation
- Understanding and Navigating the AIC Placement Screen
- Questions to Ask When Caring for an Impella Patient
- Assessing Impella Position with Echocardiography
To learn more about the Impella® platform of heart pumps, including important risk and safety information associated with the use of the devices, please visit: abiomed.com/important-safety-information