Screening for Outflow Cannula Malfunction of Left Ventricular Assist Devices (LVADs) With the Use of Doppler Echocardiography: New LVAD-Specific Reference Values for Contemporary Devices.
BACKGROUND
Echocardiographic assessment of left ventricular assist devices (LVADs) is used as a screening tool to evaluate the integrity and mechanics of the pump and circuit. We aimed to 1) establish the normal range and upper reference limit of peak velocity of the outflow cannula for the modern era of LVADs and 2) assess the clinical performance of the currently cited and newly proposed reference limits in patients with continuous-flow LVADs as a screening tool for cannula malfunction.


METHODS
LVAD outflow peak CW velocities were measured with the use of Doppler transthoracic echocardiography (TTE) in 57 patients with LVADs (44 with Heartmate II (HM2), 13 with Heartware (HW)). The average velocity and the upper and lower normal reference limits (defined as ±2 standard deviations from the mean) for each LVAD type was calculated. The upper reference limit was then used as a screening threshold for cannula malfunction.


RESULTS
The average outflow cannula peak velocity for the normal HM2 cohort was 1.86 ± 0.44 m/s with upper and lower reference limits of 2.73 m/s and 0.98 m/s, respectively. The average outflow cannula peak velocity for the normal HW cohort was 2.36 ± 0.53 m/s with upper and lower reference limits of 3.42 m/s and 1.3 m/s, respectively, which was significantly higher than the HM2 cohort (P = .004).


CONCLUSIONS
In both HM2 and HW LVADs, the average peak outflow velocity and reference limit for the normal population, as measured by Doppler TTE, was markedly higher than the currently used LVAD reference limits of 2 m/s and are significantly different between devices. Patients with peak outflow velocities above our upper reference limits should be evaluated for LVAD outflow cannula malfunction.
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois.
Jonathan
J
Grinstein
University of Chicago Medical Center, Chicago, Illinois.
Eric
E
Kruse
University of Chicago Medical Center, Chicago, Illinois.
Keith
K
Collins
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois.
Gabriel
G
Sayer
Baylor College of Medicine, Center for Medical Ethics and Health Policy, Houston, TX.
Savitri
S
Fedson
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois.
Gene H
GH
Kim
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois.
Nitasha
N
Sarswat
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois.
Sirtaz
S
Adatya
University of Chicago Medical Center, Chicago, Illinois; Department of Surgery, University of Chicago Medical Center, Chicago, Illinois.
Takeyoshi
T
Ota
University of Chicago Medical Center, Chicago, Illinois; Department of Surgery, University of Chicago Medical Center, Chicago, Illinois.
Valluvan
V
Jeevanandam
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois.
Victor
V
Mor-Avi
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois. Electronic address: nuriel@medicine.bsd.uchicago.edu.
Nir
N
Uriel
University of Chicago Medical Center, Chicago, Illinois; Department of Medicine, University of Chicago Medical Center, Chicago, Illinois.
Roberto M
RM
Lang
D000328:Adult; D000368:Aged; D000072601:Cannula / Q000009:adverse effects; D002423:Cause of Death; D015331:Cohort Studies; D015150:Echocardiography, Doppler / Q000379:methods*; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000401:mortality* / Q000601:surgery*; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D011475:Prosthesis Failure; D012016:Reference Values; D018570:Risk Assessment; D015996:Survival Rate; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*
LVAD; device malfunction; outflow cannula