[3] Hemostasis and Bleeding Disorders Flashcards Preview

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Flashcards in [3] Hemostasis and Bleeding Disorders Deck (66):
1

What is the goal of Primary Hemostasis?

Formation of a platelet plug

2

What is the goal of Secondary Hemostasis?

Stabilization of the platelet plug

3

What is the first reaction of a vessel to injury?

Vasoconstriction

4

What mediates the initial vasoconstriction of the damaged vessel?

Release of endothelin from damaged vessels

5

Platelets bind to VWF using?

GP1b Receptor

6

Where does Von Willebrand Factor come from?

Platelets
Weibel-Palade Bodies of Endothelial Cells (Vast majority)

7

Function of ADP

Promotes exposure of GpIIb/IIIa receptor on platelets

8

Function of GPIIb/IIIa

Allows platelet aggregation

9

Platelet degranulation releases these two mediators that are important for platelet aggregation

ADP
TXA2

10

Function of TXA2

Platelet aggregation

11

What is the linking molecule of GpIIb/IIIa for platelet aggregation?

Fibrinogen

12

Disorders of primary hemostasis are usually due to?

Platelet Abnormalities

13

Define: Purpura

~3mm size of skin bleeding

14

Define: Ecchymoses

>1cm size of skin bleeding

15

Having a platelet count less than this amount is associated with appearance of symptoms

<50,000/uL

16

This disease is an autoimmune production of IgG against platelet antigens

Idiopathic Thrombocytic Purpura

17

This disease is the most common cause of Thrombocytopenia in Children and Adults

Idiopathic Thrombocytic Purpura

18

[Pathophysiology]

Acute Idiopathic Thrombocytic Purpura

Autoantibodies (IgG) made in the spleen bind platelets, which are then consumed by macrophages in the spleen

19

[Treatment]

Acute Idiopathic Thrombocytic Purpura

Supportive

The disease is self-limiting and should resolve within weeks

20

What could you give a patient to raise platelet count with symptomatic bleeding in ITP?

IVIG

Short-lived effect as the spleen targets the exogenous Igs, leaving the platelet bound Igs free

21

What is the final treatment resort in cases of refractory ITP?

Splenectomy

22

[Pathophysiology]

Microangiopathic Hemolytic Anemia

Pathologic formation of platelet microthrombi in small vessels

23

Under microscopy, what is the characteristic RBC morphology when a patient has microangiopathic hemolytic anemia?

Schistocytes

24

Thrombotic Thrombocytopenic Purpura is caused by a decrease of what enzyme?

ADAMTS13

(Cleaves vWF multimers into smaller monomers for degradation)

25

Most common cause of TTP

Acquired autoantibody to ADAMTS13

(Classically seen in adult females)

26

Cause of Hemolytic Uremic Syndrome

Endothelial damage from drugs or infections

27

HUS is classically seen in which patients?

Children with E. coli O157:H7 Dysentery

28

What does E. coli release to damage endothelial cells in HUS?

E. coli verotoxin

29

Is the PT/PTT value elevated, unchanged, or decreased in patients with TTP/HUS?

Normal

30

These cells undergo hyperplasia in bone marrow in patients with TTP/HUS

Megakaryocytes

(To produce more platelets)

31

[Treatment]

TTP/HUS

Plasmapheresis and Corticosteroids

32

This disease is characterized by a Genetic GP1b deficiency

What is impaired?

Bernard-Soulier Syndrome

Platelet adhesion is impaired

33

This disease is characterized by a Genetic GIIb/IIIa deficiency

What is impaired?

Glanzmann Thrombasthenia

Platelet aggregation is impaired

34

This drug irreversibly inactivates cyclooxygenase

Acetylsalicylic Acid

35

End product of the coagulation cascade

Thrombin

36

Activation of Factors of the Coagulation Cascade require?

1. Exposure to activation factors
2. Phospholipid surface of proteins
3. Calcium

37

What does PT measure?

Extrinsic and Common Pathways

38

What does PTT measure?

Intrinsic and Common Pathways

39

What activates Factor XII?

Subendothelial Collagen

40

What activates Factor VII?

Tissue Thromboplastin

41

This disease is characterized by a Genetic Factor VIII deficiency

Hemophilia A

42

This disease is characterized by a Genetic Factor IX deficiency

Hemophilia B

43

What is the PT/PTT findings in a patient with Hemophilia A

What is the platelet count and bleeding time?

Elevated PTT
Normal PT
Normal Platelet
Normal Bleeding Time

44

[Treatment]

Hemophilia A

Recombinant Factor VIII

45

Hemophilia B is also called?

Christmas Disease

46

The most common coagulation factor inhibitor

Anti-FVIII

47

How can you differentiate an Anti-FVIII from Hemophilia A?

Perform a mixing study

PTT does not correct with patient's with Anti-FVIII

Patient's with Hemophilia A will have PTT Correction

48

This disease is the most common inherited coagulation disorder

Von Willebrand's Disease

49

Why do patients with Von Willebrands Disease present with increased PTT?

vWF stabilizes Factor VIII

50

[Treatment]

Von Willebrands Disease

Desmopressin

Increases vWF release from Weibel-Palade bodies of endothelial cells

51

Vitamin K is activated by?

Epoxide Reductase

52

How do you test the effect of liver failure on coagulation?

PT

53

[Mechanism of Action]

Heparin

Forms a Heparin-PF4 complex with platelets, allowing antibodies to be made against it leading to subsequent destruction

54

What is a feared complication of Heparin-induced Thrombocytopenia?

Thrombosis

Results from activation of fragments of destroyed platelets

55

[Pathophysiology]

Disseminated Intravascular Coagulopathy

Pathologic activation of the coagulation cascade causing consumption of platelets and factors as well as widespread microthrombi formation resulting in ischemia and infarction

56

Common Causes of DIC

1. Obstetric Complications
2. Sepsis
3. Adenocarcinoma
4. Acute Promyelocytic Leukemia
5. Rattlesnake Bite

57

[Laboratory Findings]

Effect of DIC on:
1. Platelet Count
2. PT
3. PTT
4. Fibrinogen
5. Name the elevated fibrin split product

1. Decreased Platelet
2. Elevated PT
3. Elevated PTT
4. Decreased Fibrinogen
5. D-Dimer

58

Best screening test for DIC

D-Dimer Test

59

[Treatment]

Disseminated Intravascular Coagulopathy

Transfuse blood products and cryoprecipitate as needed

60

What is responsible for cleavage of Fibrin

Plasmin

61

What enzyme is responsible for conversion of plasminogen to plasmin

tPA

62

[Function]

Plasmin

1. Cleaves serum fibrinogen
2. Inhibits coagulation factors
3. Inhibits platelet aggregation

63

Define: Thrombosis

Pathologic formation of an intravascular blood clot

64

Most common location of thrombosis

Deep Vein of the leg below the knee

65

Histologic presentation that can differentiate post from pre-mortem clots

Lines of Zahn

66

Three Major Risk Factors for Thrombosis

1. Disruption in blood flow
2. Endothelial cell damage
3. Hypercoagulable state