Critical Care Medicine-Neurologic Disorders>>>>>Imaging (Ultrasound)
Question 4#

A 54-year-old man is admitted to the ICU following Impella placement for cardiogenic shock. Routine screening ultrasound for Impella position shows the following parasternal long axis image. The distance between the calipers is 2 cm

Which of the following is the best next step in management?

A. Advance the Impella 1.5 cm
B. Advance the Impella 3 cm
C. Remeasure from the end of the pigtail to the aortic annulus
D. Leave the Impella in its current position

Correct Answer is A

Comment:

Correct Answer: A

The image in this case demonstrates the utility of cardiac ultrasound in assessing placement of percutaneous left ventricular assist devices. The devices are frequently placed under fluoroscopy in the cardiac catheterization laboratory, but fluoroscopy is rarely available in the ICU. A parasternal long axis view shows the Impella crossing the aortic valve and entering the LV. The device draws blood from the LV inflow port and pumps it into the aortic root via the outflow port. The inflow port should be positioned 3.5 to 4 cm beyond the aortic valve. Thus, in this case, the device should be advanced by 1.5 cm. It is important that the pigtail portion of the device is not included in the measurement.

If the device is pulled back into the aorta too far, both the inflow and outflow ports will be on the same side of the aortic valve and the device will not provide hemodynamic support. Additionally, turbulence from the aortic valve interfering with blood inflow can lead to hemolysis. If the device is advanced too far into the LV, the papillary muscles and aortic valve can interfere with inflow and outflow, respectively, leading to hemolysis. The pigtail can tangle with the mitral apparatus, leading to worsening mitral regurgitation. 

Reference:

  1. Stainback RF, Estep JD, Agler DA, et al. Echocardiography in the management of patients with left ventricular assist devices: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2015;28(8):853-909.