title: Acquired Von Willebrand syndrome is an early-onset problem in ventricular assist device patients.
abstract: OBJECTIVE
  Acquired Von Willebrand syndrome (AVWS) can contribute to bleeding complications in patients with ventricular assist devices (VADs). AVWS results from shear stress, which causes unfolding of the high-molecular-weight (HMW) multimers of Von Willebrand factor (VWF) with subsequent cleavage. Loss of the HMW multimers of VWF is the leading finding in AVWS. In consequence, binding of VWF to collagen and to platelets is impaired. The onset of AVWS after VAD implantation is not yet determined. We examined VAD patients for presence of an AVWS in the early, intermediate, and late phase after VAD implantation.
  
  
  METHODS
  Patients with a biventricular Thoratec-PVAD(®) (BVAD, n = 6) or a left-ventricular HeartMateII(®) (HMII, n = 11) were analyzed prior to VAD implantation and after 1, 3, 14, 30, and 60 days. Diagnosis of AVWS based on VWF:ristocetin cofactor activity/VWF:VWF antigen (VWF:RCo/VWF:Ag), collagen-binding capacity:VWF antigen (VWF:CB/VWF:Ag), and multimeric analysis. In addition, we analyzed the number of bleeding episodes, which required surgical intervention.
  
  
  RESULTS
  No patient had an AVWS prior to VAD implantation. An AVWS was identified already in the very early postoperative period, that is, in almost all patients on the first day and in all patients on the third day. The AVWS was also detected in the majority of patients in the further course. Nine of all 17 patients suffered bleeding complications and required a total of 25 interventions due to hemorrhages. Forty percent of re-interventions were carried out within the first 10 days after implantation; five of these were necessary within the first 24h.
  
  
  CONCLUSIONS
  The AVWS is present already in the early postoperative phase after VAD implantation. Therefore, reduced shear stress has to be an important feature of newly developed assist devices in the future.
authors.affiliation: Department of Cardiovascular Surgery, University Heart Center Freiburg - Bad Krozingen, Hugstetter Str 55, 79194 Freiburg, Germany. claudia.heilmann@uniklinik-freiburg.de
authors.forename: Claudia
authors.initials: C
authors.lastname: Heilmann
authors.forename: Ulrich
authors.initials: U
authors.lastname: Geisen
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Beyersdorf
authors.forename: Lea
authors.initials: L
authors.lastname: Nakamura
authors.forename: Georg
authors.initials: G
authors.lastname: Trummer
authors.forename: Michael
authors.initials: M
authors.lastname: Berchtold-Herz
authors.forename: Christian
authors.initials: C
authors.lastname: Schlensak
authors.forename: Barbara
authors.initials: B
authors.lastname: Zieger
mesh_terms: D015415:Biomarkers / Q000097:blood; D024042:Collagen Type I / Q000097:blood; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006801:Humans; D019106:Postoperative Hemorrhage / Q000097:blood / Q000209:etiology* / Q000601:surgery; D011184:Postoperative Period; D011474:Prosthesis Design; D012189:Retrospective Studies; D014842:von Willebrand Diseases / Q000097:blood / Q000209:etiology*; D014841:von Willebrand Factor / Q000276:immunology / Q000378:metabolism
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; C029417:Von Willebrand antigen; D014841:von Willebrand Factor