Term
| Heparin-Induced Thrombocytopenia (HIT) |
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Definition
| antibody-mediated adverse effect of heparin that substantially increases thrombotic risk; |
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Term
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Definition
| platelets are activated & release PF-4; heparin binds to PF-4 & forms a complex; heparin/PF-4 complex is highly antigenic & stimulates production of IgG antibodies; Complex then binds to Fc receptor on platelets causing further platelet activation & release of PF-4 and procagulant microparticles and induces clotting cascade |
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Term
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Definition
longer duration of heparin use;
recent previous heparin use (<100 days);
high doses of heparin;
UFH greater risk than LMWH;
females > males;
post-surgical pts > medical pts; |
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Term
| Heparin-Associated Thrombocytopenia (HAT) |
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Definition
platelets are "hiding", sequestered, or aggregated;
transient fall in Plt count by day 2-4 of therapy;
mild - >100,000 Plt;
No specific management required |
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Term
| Heparin-Induced Thrombocytopenia (HIT) |
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Definition
severe, immune-mediated IgG rxn;
suspect this problem if Plt count <150,000 or <50% of baseline;
Occurs 5-10 days after exposure;
Results in hypercoagulable state: DO NOT administer warfarin until Plt count >150,000; |
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Term
| Diagnosis & Lab Testing of HIT |
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Definition
NOT diagnosed based on thrombocytopenia or presence of heparin-dependent Abs alone;
Confirm with HIT Immunoassay (ELISA) - presence of Abs to heparin-PF4 complex; |
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Term
| Heparin-Associated Thrombocytopenia (HAT) |
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Definition
caused by platelet sequestration;
Occurs in about 30% of pts;
Onset: on days 2-4 of therapy;
Platelets: >100,000;
Reversible?: YES |
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Term
| Heparin-Induced Thrombocytopenia (HIT) |
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Definition
Cause: Immune mediated (IgG);
Incidence: 3%;
Onset: 1st exposure - 5-10 days, Recent exposure - may occur within 24 hrs;
Platelets: <100,000;
Reversible?: NO |
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Term
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Definition
D/C heparin & use alternative anticoagulants (lepirudin [Refludan], argatroban [Novastan], bivalirudin [Angiomax]);
DO NOT rechallenge w/ heparin;
DO NOT use heparin for line flushes - use normal saline (NS);
DO NOT use LMWH - cross-reactivity = 95%;
Future use of heparins should be AVOIDED (for at least 3-6 months); |
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Term
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Definition
direct irreversible thrombin inhibitor;
Administered as IV infusion;
Dose-adjust in RENAL impairment;
Start w/ lower dose than FDA has approved, and recommend bolus doses ONLY in life-threatening or limb-threatening cases;
Monitoring Parameters:
Baseline - PT, aPTT, CBC, SCr;
Goal aPTT 1.5-2 x pt's baseline or mean lab normal;
Check aPTT 4 hrs after initiation |
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Term
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Definition
direct REVERSIBLE thrombin inhibitor;
Administered as IV infusion;
Dose-adjusted in HEPATIC failure;
Monitoring Parameters:
Baseline - PT, aPTT, CBC, LFTs if liver dx is suspected;
Goal aPTT is 1.5-3;
Check aPTT 2 hrs after initiation |
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Term
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Definition
direct PARTIALLY REVERSIBLE thrombin inhibitor;
Administed as IV infusion;
Dose-adjust in RENAL impairment;
NOT USED for DVT/PE & NOT FDA-approved for prevention/treatment of thrombosis in HIT;
Monitoring Parameters:
Baseline - PT, aPTT, CBC, SCr |
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