title: Platelet-function analyzer closure times indicate shear stress-induced hemostatic abnormalities in patients with aortic valve stenosis and correlate with perioperative transfusion requirements.
abstract: BACKGROUND
  Shear stress-induced hemostatic abnormalities are highly prevalent in patients with aortic valve stenosis. In this study, we determined closure times with a platelet-function analyzer (PFA-100, Dade Behring, Marburg, Germany) in patients admitted for aortic valve replacement to assess the correlation with the severity of aortic valve stenosis, blood loss, perioperative transfusion requirements, and need for re-thoracotomy.
  
  
  METHODS
  Fifty consecutive patients (mean age [+/- SD] 68 +/- 9 years) were enrolled. Closure times of epinephrin/collagen and adenosine diphosphate (ADP)/collagen cartridges were determined at least ten days after discontinuation of antiplatelet medication and compared to those of healthy control subjects without medication.
  
  
  RESULTS
  Closure times of epinephrin/collagen (210 +/- 69 sec vs. 140 +/- 50 sec, p < 0.0001) and ADP/collagen (145 +/- 58 sec vs. 108 +/- 45 sec, p < 0.0001) cartridges were prolonged in patients with aortic valve stenosis. Intraoperative transfusion of red blood cell units was associated with the closure times of epinephrin/collagen (r = 0.28, p = 0.04) and ADP/ collagen cartridges (r = 0.28, p = 0.04). Total transfusion of red blood cell units was associated with ADP/ collagen closure times (r = 0.31, p = 0.02), but not epinephrin/collagen closure times (r = 0.26, p = 0.07). No significant association of closure times with intraoperative, postoperative and total transfusion of fresh frozen plasma units was observed.
  
  
  CONCLUSIONS
  Prolongation of closure times determined with a platelet-function analyzer is highly prevalent in patients with aortic valve stenosis and appears to reflect shear stress-induced hemostatic abnormalities. Since prolonged closure times are associated with increased perioperative transfusion of red blood cell units, the assay could significantly contribute to the identification of individuals at risk.
authors.affiliation: Department of Hemostasis and Transfusion Medicine, Heinrich Heine University Medical Center, Duesseldorf, Germany, Labomed Coagulation Centre Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Sucker
authors.forename: R B
authors.initials: RB
authors.lastname: Zotz
authors.forename: M
authors.initials: M
authors.lastname: Kurt
authors.forename: P
authors.initials: P
authors.lastname: Feindt
authors.forename: J
authors.initials: J
authors.lastname: Litmathe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000601:surgery*; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019990:Perioperative Care / Q000706:statistics & numerical data*; D010979:Platelet Function Tests / Q000009:adverse effects / Q000295:instrumentation; D011379:Prognosis; D013997:Time Factors