S6: atherosclerosis

Question 1

Define arteriosclerosis, atherosclerosis, and atheroma

Answer 1

Arteriosclerosis = hardening of the arterioles (especially those in the kidney & secondary to severe hypertension/diabetes mellitus)
Atherosclerosis = a disease of large and medium sized arteries that begins in the intima; plaques are formed in the arterial wall
Atheroma = is the necrotic core of the atherosclerotic plaque, it consists of dead cells, debris and cholesterol crystals

Question 2

Describe the cellular events that lead to formation of atherosclerotic plaques

Answer 2

1) Chronic endothelial insult
2) Lipid droplets & monocytes accumulate in the intima, lipids are oxidised & digested by macrophages (become foam cells)
3) Crowded foam cells cause the endothelium to bulge, smooth muscle cells migrate into the lesion & start to proliferate (fatty streak)
4) Plaque grows due to increasing number of foam & smooth muscle cells, some smooth muscle cells will lie over the plaque -> reinforced by collagen, elastin which results in a fibrous cap
5) Plaque gaps appear between the endothelial cells & platelets adhere to the gaps
6) Cells in the centre of the plaque and necrosis happens -> dead cells release cholesterol & cholesterol crystals form

Question 3

List the proposed theories that lead to plaque formation

Answer 3

1) Response to injury hypothesis = atherosclerosis is a chronic inflammatory response of the arterial wall initiated by injury to the endothelium
2) Encrustation hypothesis = plaques are formed by repeated thrombi overlying thrombi
3) Monoclonal hypothesis = the finding that some plaques are monoclonal or oligoclonal (hasn’t gained widespread popularity because some areas of normal arteries are clonal)

Question 4

List the macroscopic appearances of atherosclerosis

Answer 4

Fatty streak
Simple plaque
Complicated plaque

Question 5

List the microscopic appearances of atherosclerosis

Answer 5

Accumulation of foam cells
Cholesterol clefts
Disruption of internal elastic lamina

Question 6

List ways that a plaque can become complicated

Answer 6

Ulceration 
Thrombosis on the plaque
Spasm at the site of the plaque
Embolisation 
Calcification 
Haemorrhage 
Aneurysm formation
Rupture of the atherosclerotic artery

Question 7

What are aneurysms? What are the different types?

Answer 7

Aneurysms = local dilatations of an artery due to weakening of the arterial wall
Saccular aneurysm = one shaped like a sac, commonly occur in the abdominal aorta
Fusiform aneurysm = one shaped like a spindle

Question 8

What conditions can atherosclerosis cause in different areas of the body?

Answer 8

Heart = MI, chronic ischaemic heart disease, arrhythmias, cardiac failure & sudden cardiac death
Brain = transient ischaemic attacks (TIAs), cerebral infarction & multi-infarct dementia
Kidneys = hypertension & renal failure
Legs = peripheral vascular disease & gangrene
Bowel = ischaemic colitis, malabsorption & bowel infarction

Question 9

Identify modifiable and non-modifiable risk factors for the development of atherosclerosis

Answer 9

Non-modifiable: age, gender, genetic predisposition

Modifiable: hyperlipidaemia, hypertension, cigarette smoking, geography, obesity, infection

Question 10

List ways to prevent atherosclerosis

Answer 10

Decreasing total & LDL cholesterol, increasing HDL cholesterol 
Stopping smoking
Controlling hypertension
Controlling weight and regular exercise 
Sensible alcohol intake 
Treating diabetes mellitus 
Antioxidants

Question 11

List intervention strategies for atherosclerosis

Answer 11

Lipid-lowering drugs eg. statins

Thrombolysis, angioplasty, stents & coronary artery bypass grafts (CABG)