title: Effects of combined therapy of clopidogrel and aspirin in preventing thrombus formation on mechanical heart valves in an ex vivo rabbit model.
abstract: BACKGROUND
  The aim of our study was to investigate the efficacy of the combination of clopidogrel and aspirin in the prevention of thrombus formation on artificial heart valves in an experimental rabbit model as compared to anticoagulation with warfarin.
  
  
  METHODS
  Studies were performed after oral administration of clopidogrel and aspirin in group I (n=9) for 5 days, after 5+/-2 days treatment with warfarin in group II (n=9) and without medication in group III (n=9). Leaflets from Sulzer Carbomedics bileaflet valves were placed in a flow chamber. The flow chamber was filled with blood in a continuous circulation between the carotid artery and the jugular vein.
  
  
  RESULTS
  In group III, the flow chamber was clotted after a median of 15 min of circulation. Weight analysis before and after 1 h of perfusion showed that the median thrombus weight was 9.1 mg in group I, 14.4 mg in group II and 33.7 mg in group III. Further analysis by electron microscopy showed fewer platelets and erythrocytes on leaflets in group I than on leaflet surfaces in group II.
  
  
  CONCLUSIONS
  Clopidogrel and aspirin were more effective than warfarin in preventing thrombus formation on artificial heart valve leaflets in our investigation. This rabbit model with a high dosage of clopidogrel and aspirin, and a short-time exposure of the heart valve leaflets to rabbit blood under laminar flow, should be further evaluated with respect to whether it can give information about antithrombotic regimens in patients after mechanical heart valve replacement.
authors.affiliation: II Medical Department, Johannes Gutenberg-University Mainz, 55101, Mainz, Germany. xelschlitt@gmx.net
authors.forename: A
authors.initials: A
authors.lastname: Schlitt
authors.forename: B
authors.initials: B
authors.lastname: Hauroeder
authors.forename: M
authors.initials: M
authors.lastname: Buerke
authors.forename: D
authors.initials: D
authors.lastname: Peetz
authors.forename: A
authors.initials: A
authors.lastname: Victor
authors.forename: F
authors.initials: F
authors.lastname: Hundt
authors.forename: C
authors.initials: C
authors.lastname: Bickel
authors.forename: J
authors.initials: J
authors.lastname: Meyer
authors.forename: H J
authors.initials: HJ
authors.lastname: Rupprecht
mesh_terms: D000818:Animals; D001241:Aspirin / Q000008:administration & dosage / Q000494:pharmacology*; D000077144:Clopidogrel; D004353:Drug Evaluation, Preclinical; D004359:Drug Therapy, Combination; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D066298:In Vitro Techniques; D008297:Male; D008854:Microscopy, Electron; D011817:Rabbits; D013927:Thrombosis / Q000188:drug therapy / Q000473:pathology / Q000517:prevention & control*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology*; D014859:Warfarin / Q000494:pharmacology
chemical_list: D014859:Warfarin; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin