title: Left Ventricular Assist Device Design Reduces von Willebrand Factor Degradation: A Comparative Study Between the HeartMate II and the EVAHEART Left Ventricular Assist System.
abstract: BACKGROUND
  Supraphysiologic shear stress from continuous-flow left ventricular assist devices (LVADs) accelerates von Willebrand factor (vWF) degradation and predisposes patients to nonsurgical bleeding. It is unknown whether unique design characteristics of LVADs differentially affect vWF degradation. We tested the hypothesis that the centrifugal-flow EVAHEART (Evaheart, Houston, TX) left ventricular assist system (LVAS), which was designed to minimize shear stress (low operational revolutions per minute [rpm], larger flow gaps, low shear stress, flat H-Q curve), reduced vWF degradation versus the axial-flow HeartMate II (Thoratec, Pleasanton, CA) LVAD.
  
  
  METHODS
  Whole human blood was obtained from volunteer donors (n = 22). Blood was circulated for 12 hours in mock circulatory loops through a HeartMate II (n = 10; 11,400 rpm, 6.3 ± 0.8 L/min, 76 ± 2 mm Hg) or an EVAHEART LVAS (n = 12; 2,300 rpm, 5.7 ± 0.1 L/min, 80 ± 1 mm Hg). vWF degradation was characterized with electrophoresis and immunoblotting for large vWF multimers and 11 vWF degradation fragments.
  
  
  RESULTS
  The HeartMate II eliminated large vWF multimers and significantly (p < 0.05) increased 10 of 11 vWF degradation fragments at 6 and 12 hours. The increase was approximately 2.0-fold at 6 hours and 2.2-fold at 12 hours. In contrast, the EVAHEART LVAS modestly reduced large vWF multimers and significantly increased 5 of 11 and 8 of 11 vWF degradation fragments at 6 and 12 hours, respectively. The increase was approximately 1.5-fold at 6 hours and 1.7-fold at 12 hours. The EVAHEART LVAS caused significantly less degradation (p < 0.01) than the HeartMate II of the 140 kDa vWF fragment (cleavage product of ADAMTS-13, the vWF protease).
  
  
  CONCLUSIONS
  The EVAHEART LVAS caused significantly less vWF degradation than the HeartMate II in a mock circulatory loop with whole human blood. LVAD design features may minimize vWF degradation. These data may inform the design and operation of next-generation LVADs to minimize blood trauma.
authors.affiliation: Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: carlo.bartoli@uphs.upenn.edu.
authors.forename: Carlo R
authors.initials: CR
authors.lastname: Bartoli
authors.affiliation: Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Jooeun
authors.initials: J
authors.lastname: Kang
authors.affiliation: Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: David
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Jessica
authors.initials: J
authors.lastname: Howard
authors.affiliation: Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Michael
authors.initials: M
authors.lastname: Acker
authors.affiliation: Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Pavan
authors.initials: P
authors.lastname: Atluri
authors.affiliation: Evaheart Inc, Houston, Texas.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Motomura
mesh_terms: D004867:Equipment Design / Q000009:adverse effects*; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006801:Humans; D008955:Models, Cardiovascular; D014842:von Willebrand Diseases / Q000208:ethnology*; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D014841:von Willebrand Factor