title: Thromboelastographic changes following nonionic contrast medium injection during transfemoral angiography in patients with peripheral arterial occlusive disease.
abstract: OBJECTIVE
  Patients with peripheral arterial occlusive disease (PAOD) are known to be systemically hypercoagulable and there is concern that exposing them to contrast media during angiography may exacerbate that thrombotic tendency. Many in vitro studies in which blood is exposed to contrast media suggest that nonionic contrast medium (NICM) has a weaker anticoagulant effect than ionic contrast medium (ICM) and some studies suggest that NICM can lead to activation of coagulation thus increasing the risk of thrombotic events where it is employed. We have looked at the changes in coagulation adjacent to the site of contrast injection/potential angioplasty to determine the magnitude of change locally.
  
  
  METHODS
  We measured changes in the coagulability of aortic blood samples immediately before and within 2 min after injection of the last bolus of iohexol (NICM) prior to any intervention procedure in 30 patients with PAOD. Samples were analyzed using thromboelastography (TEG) to identify changes in the coagulability of the aortic blood samples.
  
  
  RESULTS
  TEG tracings of samples taken from the aorta after injection of NICM showed a significant increase in R time (time to fibrin formation) (p = 0.036) and in k time (dynamics of clot formation) (p = 0.028) and a reduction in Angle (decreased acceleration of fibrin build-up) (p = 0.013), Maximal amplitude (MA) (reduced ultimate clot strength) (p = 0.018) and Coagulation Index (CI) (p = 0.032).
  
  
  CONCLUSIONS
  These changes in TEG parameters show that the local effect of NICM is a reduction in coagulation activity rather than the activation suggested by some previous studies.
authors.affiliation: Nuffield Department of Surgery, John Radcliffe Hospital, University of Oxford, Headley Way, Headington, Oxford, OX3 7JE, UK. vkshankar@ukgateway.net
authors.forename: V K
authors.initials: VK
authors.lastname: Shankar
authors.forename: A
authors.initials: A
authors.lastname: Handa
authors.forename: J
authors.initials: J
authors.lastname: Philips-Hughes
authors.forename: P
authors.initials: P
authors.lastname: Boardman
authors.forename: R
authors.initials: R
authors.lastname: Uberoi
authors.forename: L J
authors.initials: LJ
authors.lastname: Hands
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001011:Aorta; D001157:Arterial Occlusive Diseases / Q000097:blood* / Q000000981:diagnostic imaging; D015415:Biomarkers / Q000097:blood; D001777:Blood Coagulation / Q000187:drug effects*; D001792:Blood Platelets / Q000187:drug effects; D016022:Case-Control Studies; D003287:Contrast Media / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005263:Femoral Artery; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000494:pharmacology*; D007511:Ischemia / Q000097:blood; D035002:Lower Extremity / Q000098:blood supply / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D016491:Peripheral Vascular Diseases / Q000097:blood* / Q000000981:diagnostic imaging; D011859:Radiography; D013916:Thrombelastography; D014914:Whole Blood Coagulation Time
chemical_list: D015415:Biomarkers; D003287:Contrast Media; D007472:Iohexol