title: Variable influence of heparin and contrast agents on platelet function as assessed by the in vitro bleeding time.
abstract: Both heparin and contrast agents have anticoagulant effects which are well-documented but their effects on platelets are not well-characterized. The purpose of the present study was to evaluate the sequential effects of heparin and then a contrast agent on platelet function during an angiographic procedure. Blood samples from 54 patients were obtained at baseline, after a 5000 unit bolus of heparin and after administration of a contrast agent (iohexol, n = 30: diatrizoate, n = 24) during angiography. The in vitro bleeding time (IVBT) was determined on nonanticoagulated whole blood using a hollow fiber device under physiological flow conditions. Mean IVBT at baseline was 3.6 +/- 2.7 minutes and increased to 17.0 +/- 12.3 minutes after heparin (p < 0.01). After heparin, 44.5% of the patients still had a normal IVBT (< 9.0 minutes), 11% of the patients had a moderately increased IVBT and the remaining patients had a large increase in their IVBT. When contrast was given (167 +/- 52 mls) following heparin, mean IVBT was higher in those who received diatrizoate (23.3 +/- 9.4 minutes) compared with iohexol (15.0 +/- 10.9 minutes, p < 0.05). However, 15 patients (28%) continued to have a normal IVBT after contrast and of these 80% had received iohexol.
authors.affiliation: Department of Medicine (Hematology and Cardiology Divisions), University of North Carolina School of Medicine, Chapel Hill 27599, USA.
authors.forename: L G
authors.initials: LG
authors.lastname: Melton
authors.forename: G J
authors.initials: GJ
authors.lastname: Dehmer
authors.forename: D A
authors.initials: DA
authors.lastname: Tate
authors.forename: K M
authors.initials: KM
authors.lastname: Muga
authors.forename: A
authors.initials: A
authors.lastname: Meehan
authors.forename: D A
authors.initials: DA
authors.lastname: Gabriel
mesh_terms: D000368:Aged; D001760:Bleeding Time; D003287:Contrast Media / Q000008:administration & dosage*; D017023:Coronary Angiography; D003973:Diatrizoate / Q000008:administration & dosage; D005260:Female; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D066298:In Vitro Techniques; D007472:Iohexol / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000187:drug effects*
chemical_list: D003287:Contrast Media; D003973:Diatrizoate; D007472:Iohexol; D006493:Heparin