title: High flow velocity through congenital cardiac lesions predicts preoperative platelet dysfunction.
abstract: BACKGROUND
  Platelet dysfunction resulting from abnormal fluid shear stress has been reported in adults with aortic stenosis. Blood flowing through a congenital heart defect at greater than normal velocity is subjected to increased shear stress. The primary aim was to determine whether peak flow velocity through congenital cardiac lesions predicts preoperative platelet dysfunction.
  
  
  METHODS
  The charts of 402 patients who underwent cardiopulmonary bypass and had preoperative platelet function analysis were evaluated. Platelet dysfunction was measured as a prolonged closure time (CT) in seconds with a platelet function analyzer. Echocardiography was used to determine peak velocity. The relationship between peak velocity and CT was analyzed using linear regression and Kaplan-Meier estimation.
  
  
  RESULTS
  The distribution of peak velocity was bimodal. The mean velocity of the lower group was 1.9 m/second and the higher group was 4.2 m/second. Univariate analysis showed age, weight, peak velocity, hematocrit, and Risk Adjustment for Congenital Heart Surgery score to be associated with prolonged CT. Using multivariable analysis, prolonged CT was significantly associated with peak velocity (p < 0.001). For each 1m/second increase in peak velocity the CT increased by over 9 seconds (p < 0.001). In addition, a median CT increase of more than 6 seconds was also associated with a 5 percentage point drop in hematocrit (p = 0.04).
  
  
  CONCLUSIONS
  Platelet dysfunction is associated with high blood flow velocity through congenital cardiac lesions. Lower preoperative hematocrit was associated with prolonged CT, which may suggest subclinical bleeding secondary to platelet dysfunction.
authors: Department of Surgery, Division of Pediatric Cardiac Surgery, Oregon Health & Science University.
authors: M Mujeeb
authors: MM
authors: Zubair
authors: Department of Obstetrics, Perinatal Division, Oregon Health & Science University. Electronic address: rogerhohimer@gmail.com.
authors: Alan Roger
authors: AR
authors: Hohimer
authors: Department of Pediatrics, Division of Pediatric Cardiology, Oregon Health & Science University.
authors: David K
authors: DK
authors: Bailly
authors: Department of Surgery, Division of Pediatric Cardiac Surgery, Oregon Health & Science University.
authors: Ashok
authors: A
authors: Muralidaran
authors: Department of Pediatrics, Division of Pediatric Cardiology, Oregon Health & Science University.
authors: Erin J
authors: EJ
authors: Madriago
authors: Department of Surgery, Division of Pediatric Cardiac Surgery, Oregon Health & Science University.
authors: M Haseeb
authors: MH
authors: Zubair
authors: Oregon Institute of Occupational Health Sciences, Oregon Health & Science University.
authors: Michael R
authors: MR
authors: Lasarev
authors: Department of Surgery, Division of Pediatric Cardiac Surgery, Oregon Health & Science University.
authors: Stephen M
authors: SM
authors: Langley
mesh_terms: D000704:Analysis of Variance; D001783:Blood Flow Velocity; D001791:Blood Platelet Disorders / Q000175:diagnosis* / Q000401:mortality; D006348:Cardiac Surgical Procedures / Q000379:methods / Q000401:mortality*; D002315:Cardiopulmonary Bypass / Q000379:methods / Q000401:mortality; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D016001:Confidence Intervals; D015150:Echocardiography, Doppler; D005260:Female; D005500:Follow-Up Studies; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging / Q000401:mortality / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053208:Kaplan-Meier Estimate; D008297:Male; D010979:Platelet Function Tests; D011237:Predictive Value of Tests; D057234:Preoperative Period; D012189:Retrospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D016896:Treatment Outcome