Hemodynamics, Impella Education
How is Impella CP® with SmartAssist® different from Impella CP®?
1. How is Impella CP with SmartAssist different from Impella CP?
The Impella CP with SmartAssist is more technically advanced than the Impella CP to improve ease-of use and patient management. Advancements include1:
- Faster, simplified Impella CP console set up takes less than 90 seconds
- New optical placement sensor allows for precise positioning of the pump in the aorta and left ventricle and repositioning in the ICU often without the need for catheterization lab or ultrasound imaging
- Simplified patient management with real-time displays of critical hemodynamic metrics on the Impella console including left ventricular end-diastolic pressure (LVEDP), mean arterial pressure (MAP), and cardiac power output (CPO)
- The ability to track relative change in hemodynamic metrics over time to assist in weaning and escalation of therapy
- Higher sustained flows up to 4.3 L/min
2. How is Impella CP with SmartAssist the same as Impella CP?
Both Impella CP and Impella CP with Smart Assist are axial flow transaortic cardiac support devices mounted on a 9Fr catheter with a 14Fr pump cannula that provide hemodynamic support with sustained peak flows of up to 4.3 L/min.
3. What is left ventricular end-diastolic pressure (LVEDP)?
Left ventricular end-diastolic pressure (LVEDP) refers to the pressure in the left ventricle (LV) at the end of diastolic filling and immediately before ventricular contraction.2 The normal value for LVEDP is < 12 mmHg and is elevated in patients with acute and chronic LV failure. Thus, relative changes in LVEDP provide a useful measurement to monitor the changing clinical status of a patient.
4. How is LVEDP calculated using Impella CP with SmartAssist?
LVEDP is calculated using the pressure assessed in the aorta from the optical sensor and the pressure derived from the motor. The Impella CP with SmartAssist is designed to run at a constant motor speed in response to the real-time changes in pressures in the aorta and left ventricle. The Impella system varies the amount of current supplied to the motor to maintain a constant motor speed and that variation correlates with the differential pressure (AoP – LVP) across the pump. The reliable measurement of motor current and aortic pressure provides continuous, real-time, and precise determination of the LVEDP.
5. What is cardiac power output (CPO)?
Cardiac power output (CPO) is the product of mean arterial pressure (MAP) and cardiac output (CO), CPO = MAP x CO/451, measured in watts (W) and is a measure of tissue perfusion.3 The pumping ability of the heart can be determined using CPO, an objective measure incorporating metrics of both pressure and flow. The CPO of a normal adult with CO of 5 L/min and MAP of 90 mmHg is 1 W.3 Klasnja et al. showed that CPO increased to up to 6 W in response to exercise in athletes.4 Likewise, since most of the cardiac pumping potential is harnessed during acute heart failure, measurement of CPO serves as an indicator of severity of acute heart failure and changes in CPO serves as a useful prognostic indicator.3,5
Analysis of patients enrolled in the SHOCK trial registry demonstrated a CPO of 0.53W to be the strongest predictor of in-hospital mortality. A recent report based on the National Cardiogenic Shock Initiative (NCSI) study suggested that CPO measurements along with lactate levels at 12-24 hours post-Impella® implantation predicted the overall outcomes and helped guide clinical decisions such as escalation of support early in the course of the disease.6
6. How is CPO calculated using Impella CP with SmartAssist?
CPO is the combination of two measurements: cardiac output (CO) and mean aortic pressure (MAP). The CO is entered from a reference device such as a Swan-Ganz catheter and the MAP is measured based on the location of the fiber-optic sensor on the Impella® heart pump within the aorta.7 It is recommended to enter a new CO from a reference device every 8 hours during Impella support.
7. What are the hemodynamic metrics displayed on the Impella console used for?
The hemodynamic metrics, such as left ventricular end-diastolic pressure (LVEDP), mean arterial pressure (MAP), and cardiac power output (CPO), displayed on the Impella console are used to assist in managing suction, identifying right heart failure, and weaning the Impella® heart pump.
The LVEDP screen on the Impella console displays time trends for MAP, LVEDP, and Impella flow. These trends provide information regarding the functioning of the Impella heart pump and the change in the hemodynamic status of the patient. However, these trends are to be used for informational purposes only and not as diagnostics.7
These hemodynamic metrics are useful for monitoring changes in Impella pump performance and patient status, especially during weaning and escalation of therapy. Metrics are for informational purposes and should be verified by another approved diagnostic device.
- Abiomed Press Releases. Impella SmartAssist Platform Launches at SCAI, Designed to Further Improve Patient Outcomes. http://investors.abiomed.com/news-releases/news-release-details/impella-smartassist-platform-launches-scai-designed-further.
- Chang, B.Y., et al. (2018). Sci Transl Med, 10(430), eaao2980.
- Fincke, R., et al. (2004). J Am Coll Cardiol, 44(2), 340-348.
- Klasnja, A.V., et al. (2013). Clin Physiol Funct Imaging, 33(3), 201-205.
- Cotter, G., et al. (2003). Curr Opin Cardiol, 18(3), 215-222.
- Basir, M.B., et al. (2019). Catheter Cardiovasc Interv, 93(7), 1173-1183.
- Abiomed Product Manual for Impella CP with SmartAssist. June 2019.