Thrombosis

Question 1

describe normal blood circulation

Answer 1

• tightly regulated process
• maintains blood in a fluid, clot-free state in normal vessels
• allows HAEMOSTATIC CLOT formation at local site of VASCULAR INJURY

Question 2

what are the 3 components involved in haemostasis

Answer 2

1) vascular wall
2) platelets
3) coagulation cascade

Question 3

what is thrombosis

Answer 3

• solid mass of blood constituents formed within VASCULAR SYSTEM due to inappropriate ACTIVATION OF HAEMOSTATIC PROCESSES
• poorly attached to vessel wall and prone to fragmentation

Question 4

is haemostasis pathological

Answer 4

yes

Question 5

what are the 3 predisposing factors of thrombosis

Answer 5

1) endothelial injury
2) stasis or turbulence of blood flow
3) blood hypercoagulability

Question 6

describe the 3 predisposing factors of thrombosis

Answer 6

1) endothelial injury:
- exposure of underneath ECM
- adhesion of platelet
- release of TISSUE FACTOR
2) stasis or turbulence of blood flow:
- TURBULENCE contributes to ARTERIAL and CARDIAC thrombosis
- STASIS contributes to venous thrombosis
3) blood hypercoagulability

Question 7

what are the steps of arterial thrombosis

Answer 7

ATHEROMA (turbulence, lipid-filled cells)–> ULCERATION (loss of endothelial cells and collagen exposure)–> PLATELET ADHERENCE (platelets adhere and are activated)–> THROMBOSIS (thrombus formed of alternating layers of PT, fibrin, RBC)–> partial or complete occlusion

Question 8

what are risk factors for thrombosis

Answer 8

• prolonged bed-rest/immobilization
• myocardial infarction
• atrial fibrillation
• prosthetic cardiac valves
• tissue injury, surgery, fracture, burn
• cancer
• inc age

Question 9

what are the major forms of thrombosis

Answer 9

arterial thrombosis

venous thrombosis

Question 10

describe arterial thrombosis

where does it usually start

Answer 10

• usually begin at sites of TURBULENCE or ENDOTHELIAL INJURY
• often superimposed on ATHEROSCLEROSIS
• often OCCLUSIVE
• common sites: coronary, cerebral and femoral arteries

Question 11

describe venous thrombosis
where does it usually occur
can cause what

Answer 11

• mostly commonly in SUPERFICIAL or DEEP VEINS of the leg
• can cause PULMONARY INFARCTION
• most commonly due to STASIS
• can be rapidly offset by COLLATERAL BYPASS CHANNELS (when channels form around the blockage) (O 50% asymptomatic)
• can cause local pain and oedema

Question 12

where do most venous thrombi begin

Answer 12

at valves

Question 13

what are the major fates of a thrombus

Answer 13

• PROPAGATION (growing bigger)
• EMBOLISATION (dislodging and travelling to other sites of vasculature)
• DISSOLUTION (result of fibrinolysis)
• ORGANISATION and RECANALISATION ( for older thrombus)

Question 14

what are clinical complications of thrombosis (both arterial and venous)

Answer 14

ARTERIAL - DISTAL tissue infarction
VENOUS- CONGESTION and OEDEMA due to impaired drainage
- embolism