Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs.
BACKGROUND
Implantation of a rotary blood pump (RBP) can cause non-physiological flow fields in the left ventricle (LV) which may trigger thrombosis. Different inflow cannula geometry can affect LV flow fields. The aim of this study was to determine the effect of inflow cannula geometry on intraventricular flow under full LV support in a patient specific model.


METHODS
Computed tomography angiography imaging of the LV was performed on a RBP candidate to develop a patient-specific model. Five inflow cannulae were evaluated, which were modelled on those used clinically or under development. The inflow cannulae are described as a crown like tip, thin walled tubular tip, large filleted tip, trumpet like tip and an inferiorly flared cannula. Placement of the inflow cannula was at the LV apex with the central axis intersecting the centre of the mitral valve. Full support was simulated by prescribing 5 l/min across the mitral valve. Thrombus risk was evaluated by identifying regions of stagnation. Rate of LV washout was assessed using a volume of fluid model. Relative haemolysis index and blood residence time was calculated using an Eulerian approach.


RESULTS
The inferiorly flared inflow cannula had the lowest thrombus risk due to low stagnation volumes. All cannulae had similar rates of LV washout and blood residence time. The crown like tip and thin walled tubular tip resulted in relatively higher blood damage indices within the LV.


CONCLUSIONS
Changes in intraventricular flow due to variances in cannula geometry resulted in different stagnation volumes. Cannula geometry does not appreciably affect LV washout rates and blood residence time. The patient specific, full support computational fluid dynamic model provided a repeatable platform to investigate the effects of inflow cannula geometry on intraventricular flow.
Innovative Cardiovascular Engineering and Technology Laboratory (ICETLAB), Critical Care Research Group, The Prince Charles Hospital, Chermside, QLD, 4032, Australia.|Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), Kelvin Grove, QLD, 4059, Australia.
Sam
S
Liao
School of Engineering, Griffith University, Southport, QLD, 4215, Australia.
Benjamin
B
Simpson
Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany.
Michael
M
Neidlin
Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany.
Tim A S
TA
Kaufmann
Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), Kelvin Grove, QLD, 4059, Australia. zhiyong.li@qut.edu.au.
Zhiyong
Z
Li
Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), Kelvin Grove, QLD, 4059, Australia.
Maria A
MA
Woodruff
Innovative Cardiovascular Engineering and Technology Laboratory (ICETLAB), Critical Care Research Group, The Prince Charles Hospital, Chermside, QLD, 4032, Australia.|School of Engineering, Griffith University, Southport, QLD, 4215, Australia.
Shaun D
SD
Gregory
D000072601:Cannula; D003198:Computer Simulation; D006333:Heart Failure / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology*; D006461:Hemolysis; D006801:Humans; D008943:Mitral Valve / Q000000981:diagnostic imaging; D008955:Models, Cardiovascular; D012306:Risk; D033081:Shear Strength; D013314:Stress, Mechanical; D013927:Thrombosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed
Heart failure; Left ventricular assist device; Multiphase modelling; Patient-specific