title: Effect of rotary blood pump pulsatility on potential parameters of blood compatibility and thrombosis in inflow cannula tips.
abstract: OBJECTIVE
  Rotary Blood Pump (RBP) pulsatile strategies relative to the native cardiac cycle have been widely studied because of their benefits to hemodynamics. However, the effects that inducing pulses has on the blood compatibility of ventricular assist device (VAD) support have not yet been understood. Inflow cannulae have been found to be associated with thrombosis under conventional constant speed support of RBPs. To prevent further risks to blood compatibility, it is necessary to understand the relationship between cannula tip design and the induced pulsatility. The purpose of this study was to evaluate the flow field of 5 different tip geometries under RBP pulsatile support using stereo-particle image velocimetry (PIV).
  
  
  METHODS
  Inflow cannulae with conventional tip geometries (blunt, blunt with 4 side ports, beveled with 3 side ports, and cage) and a custom designed crown tip were studied. All cannulae were interposed between a mixed-flow RBP and a silicone left ventricle. The contractile function and hemodynamics were reproduced in a mock circulation loop (MCL). The RBP was configured to induce synchronous and counter-synchronous pulses relative to cardiac cycles while supporting the failing ventricle.
  
  
  RESULTS
  Between both pulsing strategies, low shear volume (γ̇≤100/s, potential parameter of thrombus formation) showed no significant difference. However, counter-synchronous pulsatile mode induced less increase of both high shear volume (γ̇≥2778/s, potential parameter of platelet activation) and recirculation volume (V(z)>0, potential parameter of thrombus formation).
  
  
  CONCLUSIONS
  Although the clinical relationship cannot be inferred from this measurement, when considering the inflow tips only, a necessary trade-off should be made between adverse effects on blood compatibility and benefits for hemodynamics during RBP pulsatile mode.
authors.affiliation: Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen - Germany.
authors.forename: Kai Chun
authors.initials: KC
authors.lastname: Wong
authors.forename: Martin
authors.initials: M
authors.lastname: Büsen
authors.forename: Carrie
authors.initials: C
authors.lastname: Benzinger
authors.forename: René
authors.initials: R
authors.lastname: Gäng
authors.forename: Mirko
authors.initials: M
authors.lastname: Bezema
authors.forename: Nicholas
authors.initials: N
authors.lastname: Greatrex
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmitz-Rode
authors.forename: Ulrich
authors.initials: U
authors.lastname: Steinseifer
mesh_terms: D001783:Blood Flow Velocity; D062906:Cardiac Catheters / Q000009:adverse effects*; D061807:Catheter Obstruction / Q000209:etiology*; D004867:Equipment Design; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006353:Heart-Assist Devices / Q000009:adverse effects*; D008422:Materials Testing; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D011673:Pulsatile Flow; D012212:Rheology; D012307:Risk Factors; D013314:Stress, Mechanical; D013318:Stroke Volume; D013927:Thrombosis / Q000209:etiology* / Q000503:physiopathology; D013997:Time Factors; D016277:Ventricular Function, Left