HEPARIN-INDUCED THROMBOCYTOPENIA：heparin-induced血小板减少症

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1、HEPARIN-INDUCEDTHROMBOCYTOPENIAJeffreyM.Miller,MDAssistantClinicalProfessorofMedicineOliveView-UCLAMedicalCenterHeparin-InducedThrombocytopeniaHeparin-inducedthrombocytopenia(HIT)isatransientprothromboticdisorderinitiatedbyheparinMainfeatures:Thrombocytopeniaresultingfro

2、mIgG–mediatedplateletactivationInvivothrombingenerationandincreasedriskofvenousandarterialthrombosisWarkentinTE.Hematology.2003;503-509.HIT:ClinicalFindingsThrombocytopeniawithorwithoutnewthrombosis1,2Skinlesionsatheparininjectionsites1,2Acutesystemicreactions(chills,car

3、dio-respiratorydistress)afterIVheparinbolusadministration2Strongassociationwithvenousandarterialthrombosis2Absolutethrombosisrisk2:30%–75%Dependsonthepatientpopulation1.WarkentinTE,GreinacherA.Chest.2004;126:311S-337S.2.WarkentinTE.Hematology.2003;503-509.HIT:SerologicFi

4、ndingsPositivetestforHITantibodiesDiagnosticspecificitycanbeincreasedbyuseofasensitivewashedplateletactivationassayMorespecificthanapositiveantigenassayWarkentinTE,GreinacherA.Chest.2004;126:311S-337S.FrequencyofHITRiskofHITwithrespecttotypeofheparinBovinelungunfractiona

5、tedheparin(UFH)PorcinemucosalUFHLow–molecularweightheparin(LMWH)RiskofHITincreaseseachdaythatheparincontinuesbeyondday4Immunizationriskdeclinesafterday10WarkentinTE.Hematology.2003;503-509.FrequencyofHIT(cont)RiskofHITwithrespecttopatientpopulationSurgicalMedicalObstetri

6、calHighestfrequencyofHIT,5%,hasbeenreportedinpost-orthopedicsurgerypatientsreceivingupto2weeksofUFHHIToccurredinabout0.5%ofpost-orthopedicsurgerypatientsreceivingLMWHforupto2weeksWarkentinTE.Hematology.2003;503-509.PathophysiologyofHITPF4isaplatelet-specificC-X-Cchemokin

7、eReleasedinhighconcentrationsatsitesofplateletactivationHeparinbindstoPF4toformheparin-PF4complexesBindingofPF4toheparinappearstoexposenewantigenicepitopesonthesurfaceofcomplexthatleadtoantibodyformationAntibodiesaremainlyIgGIgG/heparin-PF4complexesactivateplateletsthrou

8、ghtheplateletFcreceptor,resultinginfurtherPF4releaseandamplificationofthisprocessWarkentinTE.Hematology