Flashcards in Graham Hemostasis 2012 / Exam 2 / 3rd deck / Platelet Inhibition Deck (37)
3 Choices to Inhibit Thrombin ?
- Unfractionated Heparin
- Low Molecular Weight
- Direct Antithrombins
Unfractionated-Heparin inhibits what factors?
Test of choice to monitor Heparin ?
Low molecular weight heparin (LMW)-inhibits what factor?
How many units are required to Inhibit factor IIa ?
13 + Units
How many units are required to Inhibit factor Xa ?
Heterogeneous mixture of many different size molecules that acts by enhancing the effect of antithrombin and has an Immediate action when it enters the bloodstream
- Osteoporosis associated with long term therapy
Anticoagulation and clearance are influenced by ?
Activated Clotting Time normal range ?
Threshold determined for optimal heparinization ?
100 - 150 sec
Celite times are artificially prolonged by
Low Molecular Weight Heparins have a longer biologic half-life. Name 6 LMW heparins?
Nadroparin calcium - Fraxiparin
Enoxaparin sodium - Lovenox
Dalteparin - Fragmin
Ardeparin - Normiflo
Tinzaparin - Innohep
Revipatin - Clivarine
Inhibit thrombin without requiring antithrombin
Approved medications for anticoagulation in patients with HIT ?
Hirudin and argatroban
While heparin can catalyze multiple reactions, ______ irreversibly binds to thrombin and may potentially be used up. It does however have a greater ability to inhibit thrombin activity.
snake venom which causes the calcium-independent activation of prothrombin by cleaving the 323Arg-324Ile bond, producing meizothrombin. This active form of thrombin is inhibited by hirudin (and r-hirudin), but not the heparin-AT complex.
- A direct thrombin inhibitor that reversibly binds to the thrombin active site
- Metabolized by the liver
- Monitored by ACT or APTT
Used to prevent clotting in patients with atrial fibrillation without heart valve disease
Oral thrombin inhibitor
How long does it take for patients to become HIT antibody negative ?
Approximately 3 months
Treatment Options for HIT in CPB
- Ideally, delay elective surgery until patients are antibody negative.
- Use heparin with protamine reversal during surgery
- Use alternative anticoagulants in pre and post op period
alternative anticoagulants throughout CPB for patients with HIT ?
- Oral direct Xa inhibitor, use expanded to include treatment or DVT and PE.
- No antidote available.
- Not dialyzable do to its high plasma protein binding.
Direct Xa inhibitor Cleared for prevention of stroke in non-valvular atrial fibrillation
added to counteract heparin (up to 1 U/mL) in our reagents does NOT NEUTRALIZE hirudin, r-hirudin, or argatroban
Vitamin K dependent factors ?
Protein C & S
- Inhibits vitamin K dependent factors.
- Monitor with PT test.
Warfarin or Coumadin mechanism of action ?
Antagonizes Vitamin K which in turn synthesizes Non-Functional coagulation factors II, VII, IX, X,
International Normalized Ratio (INR)
International effort to standardize reporting of prothrombin times.
INR = Patients PTT^ISI/Normal PTT
Recommended Therapeutic INR Range for Pulmonary Embolus, DVT, A-Fib, and Prophylaxis ?
2.0 - 3.0