title: Numerical washout study of a pulsatile total artificial heart.
abstract: OBJECTIVE
  For blood pumps with long term indication, blood stagnation can result in excessive thromboembolic risks for patients. This study numerically investigates the washout performance of the left pump chamber of a pulsatile total artificial heart (TAH) as well as the sensitivity of the rotational orientation of the inlet bileaflet mechanical heart valve (MHV) on blood stagnation.
  
  
  METHODS
  To quantitatively evaluate the washout efficiency, a fluid-structure interaction (FSI) simulation of the artificial heart pumping process was combined with a blood washout model. Four geometries with different orientations (0°, 45°, 90° and 135°) of the inlet valve were compared with respect to washout performance.
  
  
  RESULTS
  The calculated flow field showed a high level of agreement with particle image velocimetry (PIV) measurements. Almost complete washout was achievable after three ejection phases. Remains of old blood in relation to the chamber volume was below 0.6% for all configurations and were mainly detected opposite to the inlet and outlet port at the square edge where the membrane and the pump chamber are connected. Only a small variation in the washout efficiency and the general flow field was observed. An orientation of 0° showed minor advantages with respect to blood stagnation and recirculation.
  
  
  CONCLUSIONS
  Bileaflet MHVs were demonstrated to be only slightly sensitive to rotation regarding the washout performance of the TAH. The proposed numerical washout model proved to be an adequate tool to quantitatively compare different configurations and designs of the artificial organ regarding the potential for blood stagnation where experimental measurements are limited.
authors.affiliation: Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University and University Hospital Aachen, Aachen - Germany.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Sonntag
authors.forename: Tim A S
authors.initials: TA
authors.lastname: Kaufmann
authors.forename: Martin R
authors.initials: MR
authors.lastname: Büsen
authors.forename: Marco
authors.initials: M
authors.lastname: Laumen
authors.forename: Felix
authors.initials: F
authors.lastname: Gräf
authors.forename: Torsten
authors.initials: T
authors.lastname: Linde
authors.forename: Ulrich
authors.initials: U
authors.lastname: Steinseifer
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D006354:Heart, Artificial; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011673:Pulsatile Flow / Q000502:physiology*