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Cardiovascular > Atheroma, thrombosis, embolism and infarction > Flashcards

Atheroma, thrombosis, embolism and infarction Flashcards

1
Q

What is an atheroma?

A

Fibro-fatty plaques
(porridge-like tumour)
Refers to plaques found particularly in elastic and medium-to-large muscular arteries

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2
Q

What is atherosclerosis?

A

Porridge-like hardness

The consequence of atheroma

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3
Q

What is arteriosclerosis?

A

Hardening of the arteries
Atheroma is one cause
Other causes include age-related sclerosis an calcification

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4
Q

Risk factors of atheroma

A 
Age
Male sex
Genetics
Hyperlipidaemia
Hypertension
Smoking
Diabetes mellitus
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5
Q

Describe the pathogenesis of atheroma

A

Chronic endothelial injury/dysfunction
Accumulation of intimal lipid and foamy macrophages
Smooth muscle proliferation
Fibrosis forming a fibro-lipid plaque
Plaque injury- thrombosis and haemorrhage

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6
Q

What is the difference between a complicated and uncomplicated plaque?

A 
Uncomplicated= thin fibrous cap
Complicated= superimposed thrombi due to ulceration of thin cap= haemorrhage
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7
Q

Where do atheroma’s occur?

A

Elastic and medium-to-large muscular arteries

  • Abdominal aorta
  • Coronary arteries
  • Popliteal arteries
  • Descending thoracic aorta
  • Internal carotid arteries
  • Vessels of the circle of Willis (base of the brain)
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8
Q

What are the complications of atheroma?

A 
Calcification
Ulceration
Plaque rupture
Haemorrhage
Thrombosis
Aneurysmal dilation
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9
Q

What do the complications of atheroma lead to?

A

Vessel obstruction and downstream ischaemia

External vessel rupture may also occur, particularly with abdominal aortic aneurysms

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10
Q

What are the clinical implications of atheroma?

A

Cerebral infarction
Emboli in carotid arteries= TIA/ cerebral infarction
Myocardial infarction, cardiac failure
Aneurysm rupture causes sudden death
Peripheral vascular disease with intermittent claudication- thigh (impairment of walking)
Gangrene

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11
Q

What is a thrombus?

A

Solidification of blood constituents that forms within the vascular system during life

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12
Q

What is the difference between thrombus and blood clot?

A

Pathological process- denotes formation of thrombus within uninterrupted vascular system
Solidification of blood constituents outside the vascular system or after death is termed blood clot or haematoma (particularly if formed within tissues)

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13
Q

What are the risk factors for thrombosis?

A

Endothelial injury
Abnormal blood flow
Hypercoagulability
(Virchow’s Triad)

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14
Q

Describe endothelial injury

A

Ulcerated atheromatous plaques (aorta, carotid arteries, iliac and femoral arteries, coronary arteries)
Left ventricular endocardium after myocardial infarction
Abnormal cardiac valves (rheumatic fever, infective endocarditis, prosthetic valves)

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15
Q

Describe abnormal blood flow

A

Disrupts laminar flow
Prevents dilution of clotting factors
Retards the inflow of inhibitors of clotting factors
Promotes endothelial cell activation

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16
Q

What is turbulence?

A

Contributes to the development of arterial and cardiac thrombi

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17
Q

What is stasis?

A

Important in the formation of venous thrombi

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18
Q

Describe hypercoagulability

A

Alteration of the blood coagulation mechanism (particularly platelets and the clotting cascade) that in some way predisposes to thrombosis
May be a genetic predisposition (protein S/C deficiency)
May be acquired (after surgical procedures)

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19
Q

What are the types of thrombi?

A

Mural
Arterial
Venous

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20
Q

Describe a mural thrombi

A

Applied to one wall of the underlying structure

Occur in the capacious cavities of the cardiac chambers and the aorta

21
Q

Describe arterial thrombi

A

Usually occlusive
May be mural
Frequent in coronary, carotid, cerebral and femoral arteries

22
Q

Describe venous thrombosis

A

Also termed phlebothrombosis (not to be confused with thrombophlebitis)
Occurs typically in pelvic and leg veins in association with stasis

23
Q

Describe the morphology of thrombi

A

Histological appearance typically shows alternating pale (band of fibrin and platelets) and dark (red band of red blood cells) ‘lines of Zahn’

24
Q

What direct complications occur due to thrombosis in artery or vein?

A

Occlusion
Embolism- arterial= distal, venous= proximal
Arterial occlusion

25
Q

What is arterial occlusion?

A

loss of pulses distal to thrombosis, area becomes cold, pale, painful, eventually tissue dies and gangrene results

26
Q

What are the types of venous thrombosis?

A

Superficial (saphenous system)

Deep

27
Q

Symptoms of superficial venous thrombosis

A 
Congestion
Swelling
Pain
Tenderness
Rarely embolise
28
Q

Symptoms of deep venous thrombosis

A

Foot and ankle oedema

May be asymptomatic and recognised only when they have embolised (to the lung)

29
Q

What are the outcomes of venous thrombosis?

A

Resolution
Embolization to the lungs
Organised and incorporated into wall
Organised and recanalized

30
Q

What is an embolus?

A

Detached intravascular solid, liquid or gaseous mass that is carried by the blood to a site distant from its point of origin
99% all emboli arise from thrombi (thromboembolism)
Implied unless otherwise qualified

31
Q

What are the less common. rare forma of emboli fragments?

A 
Bone or bone marrow
Atheromatous debris
Droplets of fat
Tumour cells
Foreign bodies (such as bullets)
Bubbles of air or nitrogen
32
Q

What are the types of embolism?

A 
Pulmonary
Systemic
Amniotic fluid
Air 
Fat
33
Q

Describe pulmonary embolism

A

Embolism to pulmonary arteries
Occlusion of large or medium-sized pulmonary artery is embolic in origin until proved otherwise
Most arise in thrombi within the large deep veins of the lower leg
The next most common origin is pelvic veins, in association with pelvic masses

34
Q

What is a ‘saddle’ pulmonary embolism?

A

Large emboli may impact in the main pulmonary artery or lodge at the bifurcation as a saddle embolus
Associated with collapse and sudden death- circulatory obstruction

35
Q

What happens to smaller pulmonary emboli?

A

Travel out into the more periphery pulmonary arteries
If of intermediate size- cause pulmonary infarction (especially with cardiac failure)
If very small and recurrent- pulmonary hypertension

36
Q

What is a paradoxical embolism?

A

In the presence of an interatrial or interventricular defect, they may gain access to the systemic circulation

37
Q

Describe a pulmonary infarction

A

Typically haemorrhagic
The base of the infract faces the pleural surface
Patients present with haemoptysis- coughing up blood and/or pleuritic chest pain (pain on inspiration)

38
Q

What is systemic embolism?

A

Emboli that travel through the systemic arterial circulation

80-85% arise through thrombi within the heart

39
Q

What are the less common sources of thrombi developing from in systemic embolism?

A

Ulcerated atherosclerotic plaques
Aortic aneurysms
Infective endocarditis
Artificial heart valves and aortic grafts

40
Q

What are the major sites for systemic emboli to lodge at?

A

Lower extremities (commonest)
Brain
Viscera (mesenteric, renal, splenic arteries)
Upper limbs (much less common)

41
Q

What is an infarct?

A

Area of ischaemic necrosis caused by occlusion of arterial supply or venous drainage in a particular tissue

42
Q

What is necrosis?

A

Refers to spectrum of morphological changes that follow cell death in living tissue largely resulting from the progressive action of enzymes on the lethally injured cells

43
Q

Causes of infarction

A 
Thrombosis/ thromboembolism
Vasospasm
Expansion of atheroma
Compression of a vessel
Twisting of the vessels through torsion
Traumatic rupture
44
Q

What are the factors that influence the development of an infarct?

A
  • Nature of the vascular supply (single= spleen, dual= lung, small bowel)
  • Rate of development of occlusion (rapid more likely to cause infarction)
  • Vulnerability of affect tissue to hypoxia (more metabolically active tissues more vulnerable= heart)
  • Oxygen content of blood (hypoxia increases risk)
45
Q

What are the types of infarct?

A
  • Red (haemorrhagic)= venous occlusion (torsion)/ loose tissues/ tissues with a dual circulation (lung)
  • White (anaemic)= arterial occlusions/ solid organs (heart/ spleen)
  • Septic (infected infarcts)
46
Q

Describe a haemorrhagic infarct

A

Ovarian infarct
Venous occlusion as a result of torsion
Dark blue and haemorrhagic

47
Q

Describe the types of anaemic infracts

A
  • Splenic= wedge-shaped, white

- Renal infarct= wedge-shaped, white, rim of hyperaemia (an excess of blood in the vessels supplying an organ)

48
Q

Describe the histopathology of infarction

A
  • Ischaemic coagulative necrosis (mins-days)= CNS
  • Inflammatory response (hrs- 7 days)
  • Reparative response (1-2 wees)
  • Scarring (2 weeks- 2 months)

Cardiovascular (51 decks)

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