PATH 12 – ATHEROSCLEROSIS

Question 1

What is atherosclerosis

Answer 1

Atherosclerosis and atheroma are used interchangeably
‘Hardening of the arteries’
atherosclerosis as a chronic inflammatory response in response to endothelial injury.
Deposition of atheroma occurs on larger elastic or muscular arteries (not veins)
Note that ;
Atheroma is a fibrolipid plaque
Atherosclerosis is hardening of arteries due to plaque.

Question 2

What is the normal vasculature

Answer 2

• Arteries (elastic, muscular,distributing, small)
• Arterioles
• Capillaries
• Venules
• Veins

Question 3

What are the functions of vascular Endothelial Cells?

Answer 3

Serve as semipermeable membrane.
Maintain blood tissue interface.
Modulate vascular tone and blood flow.
Regulate immune and inflammatory reactions
Alter flow and leakage permeability
Modify lipoproteins in arterial wall → atheroma.

Question 4

What are the common common clinical consequences of Atherosclerosis?

Answer 4

Myocardial infarction / ischaemic heart disease.
Cerebral infarction (stroke).
Peripheral vascular disease.
Aortic aneurysms.
Mesenteric occlusion – ischaemic bowel.
Ischaemia/Infarction can occur from plaque occluding artery or from an embolus from the plaque.

Question 5

Explain Atherosclerosis pathogenesis

Answer 5

1Chronic endothelial injury → thrombotic potential. Endothelila dysfunction increases permeability and leukocyte adhesion.

2. Accumulation of lipoprotein (LDL with high cholesterol) in vessel wall lipid sleak into intima
3. Monocytes and leukocytes intima of blood vessel → transform to macrophages lipids are oxidised and consumed by macrophages via scavenger receptors, resulting in foam cells
4. Factors from platelets and macrophages cause migration of smooth muscle cells from media of artery to intima.
5. Smooth muscle cells collagen accumulation giving a fibrolipid plaque i.e. atheroma

Question 6

How often does Atheroma occur in Veins and why?

Answer 6

Rarely
Why not? The main factor to the endothelial damage is high pressure, which is not usual in the venous system (elastic wall is compliant)

Question 7

Differentiate Atheroma and Atherosclerosis

Answer 7

Atheroma is a fibrolipid plaque while Atherosclerosis is the thickening of the wall due to atheroma.

Question 8

Give the risk factors of atherosclerosis.

Answer 8

Age
Gender
Genetics
-Familial predisposition to atherosclerosis is most likely polygenic.
Hyperlipidaemia, failure to clearance of low density lipoproteins.
Hypertension around branches.
Cigarette smoking.
Smoking one or more packs of cigarettes per day for several years increases the death rate from IHD by up to 200%.
Diabetes mellitus.

Question 9

State the distribution of atheroma in the human body.

Answer 9

Abdominal aorta, esp around ostia of its major branches. Why around ostia? Turbulent blood flow
Coronary arteries.
Popliteal arteries.
Descending thoracic aorta.
Internal carotid and arteries of Circle of Willis.
Often widespread within an individual.
“Atheropath”

Question 10

What is Aneurysm

Answer 10

A localised abnormal dilation of a blood vessel.

Question 11

When aneurysm involves intact attenuated arterial wall eg. atherosclerotic aneurysm/ syphilitic aneurysm
TRUE/FALSE

Answer 11

True - bounded by arterial wall components or the attenuated wall of the heart.

Question 12

When aneurysm involves intact attenuated arterial wall eg. atherosclerotic aneurysm/ syphilitic aneurysm
TRUE/FALSE

Answer 12

True - bounded by arterial wall components or the attenuated wall of the heart.

Question 13

Pseudo-aneurysm defect in the vascular wall leading to an extravascular hematoma that freely communicates with intravascular space “pulsating hematoma”.

TRUE /FALSE

Answer 13

False - a breach in the vascular wall leading to an extravascular hematoma that freely communicates with the intravascular space e.g. Following trauma

Question 14

What are the types of Aneurysm

Answer 14

1.Saccular
Spherical outpouchings (involving only a portion of the vessel wall)
- often contains thrombus

2.Fusiform
Diffuse, circumferential dilation of a long vascular segment

3. Dissection aneurysm
4. False aneurysm

Question 15

What weakens wall and causes aneurysms?

Answer 15

>Atherosclerosis
>Congenital defects – berry aneurysm in Circle of Willis
>Infections (mycotic aneurysm) 
>Trauma
>Cystic medial degeneration
>Systemic diseases, e.g. vasculitis
>Syphilitic (luetic)

Question 16

Describe Atherosclerotic Aneurysms

Answer 16

Most frequently in the abdominal aorta (AAA). [saccular or fusiform]
Common in iliac arteries, the arch, and descending parts of the thoracic aorta can be involved.

Question 17

What is Abdominal Aortic Aneurysm

Answer 17

Usually positioned below the renal arteries and above the bifurcation of the aorta.
Types: saccular or fusiform.
Can be up to 15 cm in greatest diameter and of variable length.
The risk of rupture is directly related to the size of the aneurysm > 5 cms.
Important clinical factor affecting aneurysm growth is blood pressure.

Question 18

What are the two most important disorders that predispose to aortic aneurysm?

Answer 18

1. Atherosclerosis e.g Abdominal Aortic Aneurysm.

2. Hypertension e.g aneurysm of ascending aorta.

Question 19

What are the clinical Consequences of Abdominal Aortic Aneurysms?

Answer 19

> Rupture into the peritoneal cavity or retroperitoneal tissues with massive, potentially fatal, haemorrhage.
Obstruction of an artery (iliac, renal, mesenteric, or vertebral branches that supply the spinal cord) leading to ischemic tissue injury or infarction
Embolism from atheroma or mural thrombus
Impingement on an adjacent structure, such as compression of a ureter or erosion of vertebrae
Presentation as an abdominal mass (often palpably pulsating) that simulates a tumour.

Question 20

How do we manage atheroma?

Answer 20

>Control hypertension, hyperglycaemia in diabetic, stop smoking
>Reduce obesity
>Exercise
>Checking on diet
>Hyperlipidaemia (statins)

Question 21

Thoracic Aortic dissection is related to Atheroma? TRUE /FALSE

Answer 21

False.

Question 22

What is Thoracic Aortic dissection

Answer 22

Tear in the intima allows dissection of blood between and along the laminar planes of the media, resulting in the formation of a blood-filled channel within the aortic wall.
Can rupture outward, causing massive haemorrhage.
May or may not be associated with dilatation/aneurysm of the aorta (Avoid term dissecting aneurysm).

Question 23

What are the causes of Thoracic Aortic dissection?

Answer 23

More than 90% of dissections occur in men between the ages of 40 and 60 with antecedent hypertension.
Systemic or localised abnormality of connective tissue that affects the aorta (eg. Marfan syndrome).
Iatrogenic, as a complication of arterial cannulation

Question 24

What are the clinical symptoms of Aortic dissection?

Answer 24

Sudden onset of excruciating pain, usually beginning in the anterior chest, radiating to the back, and moving downward as the dissection progresses
Complications depend on the level of the aorta affected
Most serious complications occurring from the aortic valve to the arch haemopericardium
Main cause of death is rupture of the dissection outward.

Question 25

What is arterial dissection?

Answer 25

Condition that comes by when blood enters the arterial wall itself as a hematoma dissecting between its layers.

Question 26

Define aortitis

Answer 26

inflammation of the aorta

Question 27

What are the cause of Aortitis

Answer 27

Giant cell arteritis
Other arteritis
Rheumatoid arthritis
Syphilis

Question 28

What is the difference between atheroma, atherosclerosis and arteriolosclerosis?

Answer 28

> Atheroma is a Fibrolipid plaque
Atherosclerosis is Atheroma of larger arteries with fibrosis/narrowing
Arteriolosclerosis is the narrowing of small arterioles due to hypertension

Question 29

How does age increase the chances of suffering from atherosclerosis?

Answer 29

Death rates from IHD rise with each decade

Between ages 40 and 60 the incidence of myocardial infarction increases fivefold

Question 30

How does gender increase / decrease the chances of one suffering from atherosclerosis?

Answer 30

Other factors being equal, males are more prone to atherosclerosis
After menopause, the incidence of atherosclerosis-related diseases increases in women probably owing to a decrease in natural oestrogen levels.

Question 31

Explain how Hyperlipidaemia affects atherosclerosis

Answer 31

Hyperlipidaemia, failure to clearance of low density lipoproteins.
Low-density lipoprotein (LDL) delivers cholesterol to peripheral tissues.
High-density lipoprotein (HDL) mobilizes cholesterol, transporting it to the liver for excretion in the bile.
High dietary intake of cholesterol and saturated fats, (egg yolk & animal fats) raises the plasma cholesterol level.

Question 32

Explain how diabetes mellitus increases the risk of suffering from atherosclerosis.

Answer 32

Induces hypercholesterolemia and a markedly increased predisposition to atherosclerosis.
Incidence of myocardial infarction is twice as high in diabetics as in non-diabetics.
100-fold increased risk of atherosclerosis-induced gangrene of the lower extremities.