Evaluation of the HeartWare ventricular assist device Lavare cycle in a particle image velocimetry model and in clinical practice.
OBJECTIVE
Ventricular blood stasis is a concern for continuous flow mechanical support devices and might contribute to the formation of thromboembolic events. The HeartWare® Ventricular Assist System (HVAD®) is equipped with the Lavare™ cycle that is a periodic speed modulation feature designed to alter flow patterns within the left ventricle and reduce areas of potential blood stasis. Here, we report in vitro and clinical findings on the effects of the Lavare cycle.


METHODS
The effect of pump speed changes on the intraventricular flow field was examined with an in vitro particle image velocimetry model. The clinical impact of the Lavare cycle was evaluated through a retrospective review of the ReVOLVE study which includes 248 patients implanted with the HVAD following Conformité Européenne Mark in nine centres in Europe and Australia. Baseline characteristics, adverse event profiles and Kaplan-Meier survival estimates were stratified by patients using/not using the Lavare cycle.


RESULTS
Particle image velocimetry showed increased ventricular washout with an active Lavare cycle as measured by the fluid velocities and angular dispersion parameters. With the Lavare cycle on, there was also a 22% decrease in the stagnation index compared with when the Lavare cycle was off. In the ReVOLVE registry, patients with the Lavare cycle turned on (n = 215) were supported for 497 patient-years, whereas patients who did not use the speed modulation (n = 33) were supported for 39.3 patient-years. The Lavare cycle did not significantly affect patient survival as both groups had approximately an 80% survival after 1 year. Patients using the Lavare cycle had significantly fewer rates of stroke [0.06 vs 0.20 events per patient-year (EPPY), P = 0.0008], sepsis (0.03 vs 0.15 EPPY, P = 0.0003) and right heart failure (0.03 vs 0.18 EPPY, P < 0.0001) with no difference in the transplant or recovery rates among the two cohorts.


CONCLUSIONS
The Lavare cycle effectively generates ventricular washout and the adverse event profiles of ReVOLVE patients with the Lavare cycle on were better than those with the Lavare cycle off. Larger studies are warranted to verify the positive effect of the Lavare cycle and to optimize speed modulation settings, so additional clinically relevant improvements can be realized.
Department of Surgery, Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria daniel.zimpfer@meduniwien.ac.at.
Daniel
D
Zimpfer
Spectrum Health, Grand Rapids, MI, USA.
Martin
M
Strueber
Ludwig Boltzmann Cluster for Cardiovascular Research and Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
Philipp
P
Aigner
Hannover Medical School, Hannover, Germany.
Jan D
JD
Schmitto
Oslo University Hospital, Oslo, Norway.
Arnt E
AE
Fiane
Royal Perth Hospital, Perth, Australia.
Robert
R
Larbalestier
Papworth Hospital NHS Foundation Trust, Cambridge, UK.
Steven
S
Tsui
St Vincent's Clinic, Sydney, Australia.
Paul
P
Jansz
Royal Brompton and Harefield Hospital, London, UK.
Andre
A
Simon
Freeman Hospital, Newcastle upon Tyne, UK.
Stephan
S
Schueler
Ludwig Boltzmann Cluster for Cardiovascular Research and Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
Francesco
F
Moscato
Department of Surgery, Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria.|Ludwig Boltzmann Cluster for Cardiovascular Research and Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
Heinrich
H
Schima
D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D001783:Blood Flow Velocity / Q000502:physiology; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000503:physiopathology; D005060:Europe / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D006353:Heart-Assist Devices / Q000009:adverse effects; D018056:Hemorheology / Q000502:physiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D012042:Registries; D012189:Retrospective Studies; D018805:Sepsis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D020521:Stroke / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D016276:Ventricular Function / Q000502:physiology
HVAD; Lavare cycle; Left ventricular assist device; Particle image velocimetry