MoD 6 Thrombosis and Embolism

Question 0

What do blood vessels do upon injury?

Answer 0

Constrict to limit blood loss

Question 1

What 4 things does successful haemostasis depend on?

Answer 1

Vessel wall
Platelets
Coagulation system
Fibrinolytic system

Question 2

What do platelets do upon injury?

Answer 2

Adhere to damaged vessel wall and each other

Form platelet plug

Question 3

What clotting factor do both the extrinsic and intrinsic pathway activate?

Answer 3

Factor 10

Question 4

What does factor 10 activate and what does the product do?

Answer 4

Cleaves prothrombin to thrombin which converts fibrinogen to fibrin and activates factor 13 which cross links the fibrin

Question 5

Which factors does thrombin exert positive feedback on?

Answer 5

Five, eight and eleven

Question 6

What are some thrombin inhibitors?

Answer 6

Anti-thrombin iii
Alpha 1 antitrypsin
Alpha 2 macroglobulin
Protein C/S

Question 7

Inherited deficiencies in which thrombin inhibitors cause thrombophilia and thrombosis?

Answer 7

Anti thrombin iii

Protein C/S

Question 8

What is fibrinolysis?

Answer 8

Breakdown of fibrin by plasmin

Question 9

What is fibrinolytic therapy and when is it used?

Answer 9

Clot/ thrombus busters e.g streptokinase which activates plasminogen.
Very drastic only used in serious situations e.g coronary artery occlusion or thrombus cutting off circulation to a limb

Question 10

What is thrombosis?

Answer 10

Formation of a solid mass of blood within the circulatory system during life

Question 11

What is Virchow’s triad?

Answer 11

Changes in blood flow- stagnation, turbulence
Changes in vessel wall- atheroma, injury, inflammation
Changes in blood components- smokers, pregnancy
These are what causes thrombus to form

Question 12

What are the differences between arterial thrombi and venous thrombi?

Answer 12

Arterial- pale, granular, lines of zahn, lower cell content

Venous- deep red, soft, gelatinous, higher cell content

Question 13

What are the effects of arterial thrombosis?

Answer 13

Ischaemia, infarction

Depends on site and collateral circulation

Question 14

What are the effects of venous thrombosis?

Answer 14

Congestion, oedema, ischaemia ( if tissue pressure die to oedema> arterial pressure), infarction

Question 15

What are the outcomes of thrombosis?

Answer 15

Lysis- complete dissolution of thrombus. Fibrinolytic system active, blood flow re-established. Most likely with small thrombus
Propagation- progressive spread of thrombus (distally in arteries, proximally in veins)
Organisation- reparative process with in growth of fibroblasts and capillaries. Lumen remains obstructed
Recanalisation- blood flow re-established usually incompletely as a channel formed by organising thrombus
Embolism- part of thrombus breaks off, travels through blood stream and lodges at distant site e.g coronary artery causing MI

Question 16

What is an embolism?

Answer 16

Blockage of blood vessel by a solid, liquid or gas at a site distant from its origin

Question 17

Most emboli are thrombo-emboli, what are some other types?

Answer 17

Air
Amniotic fluid
Nitrogen (bends)
Medical equipment
Tumour cells

Question 18

Where will thrombi from systemic veins cause embolism?

Answer 18

Will cause pulmonary embolism in lungs as won’t get stick in large veins near heart, next place where small artery where can get stuck is, is lungs

Question 19

Where will thrombi from heart cause embolism?

Answer 19

Renal, mesenteric and other arteries

Question 20

Where will thrombi from atheromatous carotid arteries cause embolism?

Answer 20

Brain (stroke)

Question 21

Where will thrombi from atheromatous abdominal aorta cause embolism?

Answer 21

Arteries of legs

Question 22

What are the consequences of pulmonary embolisms?

Answer 22

Massive- over 60% reduction in blood flow. Rapidly fatal
Major- medium sized vessels blocked. Shortness of breath, cough, blood stained sputum
Minor- small peripheral pulmonary arteries. Asymptomatic or minor shortness of breath
Recurrent PEs cause pulmonary hypertension

Question 23

What can cause deep vein thrombosis?

Answer 23

Immobility/ bed rest
Post-operative
Pregnancy and post partum
Oral contraceptives 
Severe burns 
Cardiac failure
Disseminated cancer

Question 24

How is DVT treated?

Answer 24

Intravenous heparin- anticoagulant, co factor for anti thrombin 3
Oral warfarin- interferes with synthesis of Vit K dependent clotting factors, slow effect

Question 25

What causes fat embolism?

Answer 25

Fractures of long bones
Lacerations of adipose tissue
Gives rash, shortness of breath, confusion

Question 26

How do cerebral embolisms occur?

Answer 26

Atrial fibrillation causes stasis which causes thrombus

In left heart can go to brain and cause stroke or TIA

Question 27

What is an iatrogenic embolism?

Answer 27

Embolism due to medical treatment e.g air embolism from an injection

Question 28

What is a nitrogen embolism?

Answer 28

Nitrogen bubbles form in blood with rapid decompression

The bends

Question 29

What is disseminated intravascular coagulation (DIC)?

Answer 29

Pathological activation of coagulation mechanisms that occurs in response to a variety of diseases
Small clots form throughout body, disrupting normal coagulation as they use up all the clotting factors causing abnormal bleeding from the skin
Triggers: infection, trauma, liver disease, obstetric complications

Question 30

What is haemophilia?

Answer 30

Type A- factor 8 deficiency
Type B-factor 9 deficiency
X linked recessive so more common in boys
Varying severity, due to nonsense point mutation
Haemorrhage into major joints, synovial hypertrophy, pain
Muscle bleeding causes pressure and necrosis of nerves (painful)
Can haemorrhage into retroperitoneum or urinary tract
Treated with self administer factor replacement therapy

Question 31

What is thrombocytopenia?

Answer 31

Platelet count way below reference range
Due to: failure of platelet production
Increase in platelet destruction
Sequestering of platelets 
Usually accompanied by bone marrow disfunction e.g anaemia, leukaemia 
If due to sequestering could be DIC