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Flashcards in Thrombosis And Embolism Deck (41)
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1
Q

What is thrombosis

A

Process leading to formation of thrombus

2
Q

What is a thrombus

A

Blood clot

Solid mass made of blood constituents which have aggregated together in flowing blood of the lumen of a blood vessel

3
Q

What are the main constituents of a thrombus

A

Platelets and fibrin

4
Q

What types of thrombosis are there?

A

Physiological and pathological

5
Q

When is thrombosis a normal mechanism?

A

Preventing bleeding when a vessel wall is breached

6
Q

When does thrombosis become pathological

A

When it is not controlled by fibrinolysis

7
Q

Describe normal thrombosis

A

Vessel wall breached
Circulating platelets aggregate to plug gap
Platelets release factors which trigger cascade
Cascade converts fibrinogen to fibrin
Fibrin bind together platelets and entrap WBCs and RBCs

8
Q

What is fibrinolysis

A

Breaking down of fibrin so the thrombus dissolves
Plasmin is the enzyme
Broken down products are the fibrin degradation products

9
Q

What occurs to control the side of the thrombus

A

Plasminogen converted to plasmin by plasminogen activator (tissue plasminogen activator)
Plasminogen and t-PA bund to fibrin
t-PA converts nearby plasminogen to plasmin which begins to degrade the fibrin

10
Q

Describe pathological thrombosis

A

Occurs when thrombus enlarges beyond vessel healing requirements and continues to grow
Beyond certain thrombus size and rate of development, intrinsic fibrinolytic system is incapable of controlling size of thrombus

11
Q

How does the thrombus grow in pathological thrombus?

A

Accretion of layer upon layer

If it continues unrestrained, reddish-brown mass is produced in vessel

12
Q

What are D-dimers?

A

Breakdown product of a fibrin mesh, stabilised by factor XIII

13
Q

What factors predispose thrombus formation?

A
  1. Damage to vessel wall (endothelium)
  2. Stasis (slow or turbulent)
  3. Change in character of blood (increased platelets, RBCs)
14
Q

Where does pathological thrombosis occur?

A

Arteries
Veins
Heart

15
Q

Most prominent predisposition factor of arteries?

A

Vessel wall damage

16
Q

Most prominent predisposition factor of veins?

A

Stasis

17
Q

Most prominent predisposition factor of the heart?

A

Ventricles - chamber wall damage
Atrium - stasis
Heart valves - valve surface damage

18
Q

What effect will a thrombus forming an atheroma in a coronary artery?

A

Tissue will become ischaemic

Tissue death due to reduced blood flow - infarction

19
Q

What effect will a thrombus formed in a vein in a leg cause?

A

Stays there - swollen leg

Moves - pulmonary embolism

20
Q

What effect will a thrombus formed in a heart chamber cause?

A

Inflammation, sticky, thrombus forms

Stroke (left ventricle)

21
Q

What woukd white markings be in a heart?

A

Scarring from MI

22
Q

What effect would a thrombus on mitral valve cause?

A

Same as having thrombus in left ventricle

23
Q

What happens to thrombus?

A
Lysed by intrinsic fibrinolysis - rare
Completely block lumen - occlusion
Undergo organisation and recanalisation 
Extend locally - propagation
Fragment or detach and travel elsewhere- thromboembolism
24
Q

What happens when a thrombus occludes a vessel?

A

Artery - stops flow of blood, cuts off oxygen to issue - infarction
Vein - prevents venous drainage of tissues, blood pools - congestion and infarction (often haemorrhagic)

25
Q

What occurs if the thrombus organises and recanalises?

A

New vessels grow into thrombus
Vascular granulation tissue develops
Fibroblasts invade and deposit collagen
Fibrovascular granulation tissue develops

26
Q

Embolism

A

Transference is abnormal material by blood stream with eventual impact action of the material in a vessel distal to origin

27
Q

Most important materials to embolise

A

Thrombus

Cancer cells

28
Q

Where does a thrombus in an artery or left side of the heart embolise to?

A

Systemic arterial system

29
Q

What will a blockage of brain arteries cause?

A

Stroke

30
Q

What will blockage of lower limb arteries cause?

A

Gangrene of legs

31
Q

What will blockage of mesenterric arteries cause?

A

Bowel necrosis

32
Q

What will blockage of renal arteries cause

A

Kidney infarct

33
Q

What will blockage of splenic artery cause

A

Splenic infarct

34
Q

Where will a thrombus in a systemic vein embolise to?

A

Pulmonary artery branch - pulmonary embolus

35
Q

Impact of pulmonary embolus on patient

A

Small - small peripheral lung infarct

Large - sudden death

36
Q

Examples of systemic emboli

A

Thrombus in mitral valve - tissue necrosis in kidney
Left ventricular wall - brain, secondary haemorrhage
Calf - pulmonary embolism

37
Q

What is a VTE risk assessment ?

A

Risk assessment for venous thromboembolism

38
Q

How does VTE RA work?

A
Active cancer treatment/cancer
Age >60
Dehydration 
Known 
Obesity
One or more significant medical 
Personal or first degree relative
Hormone replacement therapy 
Oestrogen containing contraceptive
Varicose veins with phlebitis
Pregnancy
39
Q

Other materials that are embolised

A

Fat and marrow
Air
Nitrogen
Amniotic fluid

40
Q

D-dimer test

A

Diagnose thrombus presence

If negative for D-dimer, unlikely to have serious venous blood clot

41
Q

What is infarction

A

Special kind of necrosis due to reduced blood flow