Graham Hemostasis 2012 / Exam 2 / 3rd deck / Platelet Inhibition

Question 1

3 Choices to Inhibit Thrombin ?

Answer 1

• Unfractionated Heparin
• Low Molecular Weight
  Heparins
• Direct Antithrombins

Question 2

Unfractionated-Heparin inhibits what factors?

Answer 2

Factor IIa

Factor Xa

Question 3

Test of choice to monitor Heparin ?

Answer 3

PTT

Question 4

Low molecular weight heparin (LMW)-inhibits what factor?

Answer 4

Xa

Question 5

How many units are required to Inhibit factor IIa ?

Answer 5

13 + Units

Question 6

How many units are required to Inhibit factor Xa ?

Answer 6

5 units

Question 7

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

Answer 7

Unfractionated Heparin

Question 8

Heparin Risks

Answer 8

• Hemorrhage
• Heparin-induced
  thrombocytopenia
• Osteoporosis associated with long term therapy

Question 9

Anticoagulation and clearance are influenced by ?

Answer 9

Chain Length

Question 10

Activated Clotting Time normal range ?

Threshold determined for optimal heparinization ?

Answer 10

100 - 150 sec

> 400 sec

Question 11

Celite times are artificially prolonged by

Answer 11

Aprotinin

Question 12

Low Molecular Weight Heparins have a longer biologic half-life. Name 6 LMW heparins?

Answer 12

Nadroparin calcium - Fraxiparin
Enoxaparin sodium - Lovenox
Dalteparin - Fragmin
Ardeparin - Normiflo
Tinzaparin - Innohep
Revipatin - Clivarine

Question 13

Direct Antithrombins

Answer 13

Inhibit thrombin without requiring antithrombin

Question 14

Approved medications for anticoagulation in patients with HIT ?

Answer 14

Hirudin and argatroban

Question 15

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.

Answer 15

hirudin

Question 16

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.

Answer 16

Ecarin

Question 17

Argatroban (ACOVA)

Answer 17

• A direct thrombin inhibitor that reversibly binds to the thrombin active site
• Metabolized by the liver
• Monitored by ACT or APTT

Question 18

Used to prevent clotting in patients with atrial fibrillation without heart valve disease
Oral thrombin inhibitor

Answer 18

Pradaxa

Question 19

How long does it take for patients to become HIT antibody negative ?

Answer 19

Approximately 3 months

Question 20

Treatment Options for HIT in CPB

Answer 20

• 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

Question 21

alternative anticoagulants throughout CPB for patients with HIT ?

Answer 21

Bivalirudin

Question 22

• 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.

Answer 22

Xarelto (rivaroxaban)

Question 23

Direct Xa inhibitor Cleared for prevention of stroke in non-valvular atrial fibrillation

Answer 23

Eliquis (apixaban)

Question 24

Polybrene

Answer 24

added to counteract heparin (up to 1 U/mL) in our reagents does NOT NEUTRALIZE hirudin, r-hirudin, or argatroban

Question 25

Vitamin K dependent factors ?

Answer 25

II
VII
IX
X
Protein C & S

Question 26

Coumadin

Answer 26

• Inhibits vitamin K dependent factors.

- Monitor with PT test.

Question 27

Warfarin or Coumadin mechanism of action ?

Answer 27

Antagonizes Vitamin K which in turn synthesizes Non-Functional coagulation factors II, VII, IX, X,

Question 28

International Normalized Ratio (INR)

Answer 28

International effort to standardize reporting of prothrombin times.

INR = Patients PTT^ISI/Normal PTT

Question 29

Recommended Therapeutic INR Range for Pulmonary Embolus, DVT, A-Fib, and Prophylaxis ?

Answer 29

2.0 - 3.0

Question 30

Recommended Therapeutic INR Range for prosthetic heart valves and recurrent systemic embolisms?

Answer 30

3.0 - 4.5

Question 31

3 medications for Anti-platelet Therapy ?

Answer 31

Aspirin
Plavix
Effient

Question 32

Plavix (clopidogrel)

Answer 32

• Inhibits ADP receptor on platelets (P2Y12)

- Some monitor with “aspirin tolerance testing” aka mini-aggregation studies

Question 33

Effient (prasugrel)

Answer 33

• Inhibits ADP receptor on platelets (P2Y12)
• Claims to have more rapid inhibition of platelet activity than Plavix.
• Often used in conjunction with aspirin

Question 34

Thrombolytic Therapy

Answer 34

Drugs or enzymes that act on pre-existing thrombi.
- Streptokinase
- Pro-urokinase
- Tissue plasminogen  
   activator (tPA)
   greater specificity for fibrin

Question 35

Anti-Fibrinolytic Therapy

Answer 35

Inhibit fibrinolysis by blocking the binding sites of plasminogen to prevent formation of plasmin.

• Epsilon amino caproic acid
  (EACA)
• Tranexemic acid

Question 36

Epsilon Amino Caproic Acid (EACA, Amicar)

Answer 36

Synthetic anti-fibrinolytic forms an irreversible complex with plasminogen or plasmin

Question 37

Tranexemic Acid

Answer 37

Synthetic anti-fibrinolytic forms an irreversible complex with plasminogen or plasmin

10X as potent