title: Impairment of platelet retention rate in patients with severe aortic valve stenosis.
abstract: BACKGROUND
  Recent reports revealed the presence of acquired von Willebrand syndrome type 2A in patients with aortic valve stenosis (AS). von Willebrand factor (vWF) has been shown to play a vital role in platelet adhesion. Therefore, we measured the platelet retention rates, which reflect platelet adhesion, in patients with severe AS.
  
  
  METHODS
  In addition to echocardiography, routine blood screening tests were performed and the platelet retention rates were measured using collagen-coated bead columns in 21 patients with severe AS and in 21 control subjects.
  
  
  RESULTS
  Patients with severe AS showed the maximum aortic valve pressure gradients of 110.9±22.7 mmHg, and effective orifice areas of 0.59±0.20 cm2. The results of routine blood tests in patients with severe AS were comparable to those of control subjects; however, the platelet retention rates in the AS patients (7.3±5.0%) were significantly lower than those in control subjects (30.5±11.8%, p<0.001). A significant negative correlation was observed between maximum aortic valve pressure gradients and platelet retention rates (r = -0.81, p<0.001). In 8 patients with severe AS, the platelet retention rates increased from 5.8±3.6% to 16.0±2.4% after aortic valve replacement (p<0.001).
  
  
  CONCLUSIONS
  These findings suggest that impairment of platelet retention rate is seen in almost all patients with severe AS. Clinicians should be aware of the possibilities of vWF-mediated platelet dysfunction and bleeding tendency in patients with severe AS.
authors.affiliation: Fourth Department of Internal Medicine, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo City, Shimane 693-8501, Japan. Electronic address: yukihiro@med.shimane-u.ac.jp.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Tanabe
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshitomi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Adachi
authors.forename: Saki
authors.initials: S
authors.lastname: Ito
authors.forename: Takashi
authors.initials: T
authors.lastname: Sugamori
authors.forename: Akihiro
authors.initials: A
authors.lastname: Endo
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: Teiji
authors.initials: T
authors.lastname: Oda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000097:blood* / Q000150:complications* / Q000503:physiopathology / Q000601:surgery; D001696:Biomechanical Phenomena; D001791:Blood Platelet Disorders / Q000097:blood* / Q000209:etiology*; D001794:Blood Pressure; D005260:Female; D019918:Heart Valve Prosthesis Implantation; D006470:Hemorrhage / Q000097:blood / Q000209:etiology; D006801:Humans; D008297:Male; D010973:Platelet Adhesiveness; D012720:Severity of Illness Index; D033081:Shear Strength; D013314:Stress, Mechanical; D056728:von Willebrand Disease, Type 2 / Q000097:blood* / Q000150:complications*; D014841:von Willebrand Factor / Q000502:physiology*
chemical_list: D014841:von Willebrand Factor
keywords: Aortic valve stenosis; Platelet retention rate; von Willebrand factor