title: Thrombogenic evaluation of two mechanical heart valve prostheses using a new in-vitro test system.
abstract: OBJECTIVE
  The continued risk of thrombus formation and subsequent thromboembolism remains a major problem with prosthetic mechanical heart valves, and patients must undergo lifelong anticoagulation therapy. Thus, it is necessary to localize and analyze critical thrombogenic regions in heart valves for their optimal design. The study aim was to verify the application of a new in-vitro test system for thrombogenic investigation, and to assess two different types of prosthetic mechanical heart valves for the detection of thrombus formation and regions of thrombogenic potential in prosthetic valves.
  
  
  METHODS
  The test system was specifically designed and manufactured at the Helmholtz Institute Aachen for the in-vitro determination of thrombogenic effects in mechanical heart valves. Porcine whole blood was used as a test fluid. In order to examine the state of the blood and function of the valves, the activated clotting time (ACT) and pressure differences across the valves were measured during testing.
  
  
  RESULTS
  The local thrombogenic areas within the tested valves, and consequent thrombus formation caused by the valves, were detected using the test system. The in-vitro test results correlated well to reported in-vivo animal test results with these valves.
  
  
  CONCLUSIONS
  Correlation of the present in-vitro results with previously reported in-vivo results confirmed the reliability of the new system to detect local thrombogenic areas in mechanical heart valves. The new system represents a cost-effective method for optimizing the design and development of new prosthetic mechanical heart valves.
authors.affiliation: Helmholtz Institute for Biomedical Engineering, Chair of Applied Medical Engineering, RWTH Aachen University, Aachen, Germany. kim@hia.rwth-aachen.de
authors.forename: Chong-Hyon
authors.initials: CH
authors.lastname: Kim
authors.forename: Ulrich
authors.initials: U
authors.lastname: Steinseifer
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmitz-Rode
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology; D006350:Heart Valve Prosthesis; D006493:Heparin / Q000494:pharmacology; D066298:In Vitro Techniques; D008422:Materials Testing / Q000295:instrumentation* / Q000379:methods; D011474:Prosthesis Design; D013552:Swine; D013927:Thrombosis / Q000209:etiology*; D014914:Whole Blood Coagulation Time
chemical_list: D000925:Anticoagulants; D006493:Heparin