Lecture 4.2 - Atherosclerosis

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Questions and Answers

What is the mechanism of endothelial damage caused by hypertension in atherosclerosis?

Stimulation of proliferation and migration of smooth muscle cells

Uncertain mechanism (correct)

Direct pressure-induced damage

Increased permeability to lipoproteins

Which of the following is a risk factor for atherosclerosis that is also associated with high risk of cerebrovascular and peripheral vascular disease?

Hypertension

Lack of exercise

Diabetes mellitus (correct)

Oral contraceptives

What is the role of macrophages in atherosclerosis?

Produce intercellular matrix

Stimulate proliferation and migration of smooth muscle cells

Oxidise LDL and take up lipids to become foam cells (correct)

Synthesise collagen and proteoglycans

Which of the following is a microscopic feature of atherosclerosis?

Foam cell formation Signup and view all the answers

What is the role of platelets in atherosclerosis?

Key role in haemostasis Signup and view all the answers

Which of the following infections is a risk factor for atherosclerosis?

All of the above Signup and view all the answers

What is the role of endothelial cells in atherosclerosis?

All of the above Signup and view all the answers

Which of the following is a clinical complication of atherosclerosis?

Both A and B Signup and view all the answers

What is the characteristic feature of a fatty streak in atherosclerosis?

Yellow discolouration with no bulging Signup and view all the answers

Which of the following is a non-modifiable risk factor for atherosclerosis?

Genetic predisposition Signup and view all the answers

What is the primary component of fibro-fatty plaques in atherosclerosis?

Lipid containing macrophages Signup and view all the answers

What is a clinical complication of atherosclerosis?

Ruptured abdominal atherosclerotic aneurysm Signup and view all the answers

What is an early microscopic feature of atherosclerosis?

Proliferation of smooth muscle cells Signup and view all the answers

What is the primary mechanism of the response to injury hypothesis in atherosclerosis?

Endothelial dysfunction leading to platelet adhesion Signup and view all the answers

Which of the following is a modifiable risk factor for atherosclerosis?

Cigarette smoking Signup and view all the answers

What is the term used to describe the formation of atherosclerotic plaques?

Intimal lesions Signup and view all the answers

What is the complication of atherosclerosis that can lead to myocardial infarction?

Acute atherothrombotic occlusion Signup and view all the answers

What is the characteristic feature of a complicated plaque in atherosclerosis?

Calcification and hemorrhage Signup and view all the answers

Study Notes

Atherosclerosis

Atherosclerosis is a type of arteriosclerosis, characterized by the accumulation of intracellular and extracellular lipid in the intima and media of large and medium-sized arteries.
Does not affect veins or capillaries.
Slowly progressive, build-up of fat (cholesterol) within the artery wall, characterized by intimal lesions called atheroma, atheromatous, or fibro-fatty plaques.

Pathogenesis of Atherosclerosis

Response to injury hypothesis:
- Initiated by endothelial dysfunction
- Chronic inflammatory response - presence of macrophages
- Migration of smooth muscle cells (SMC) from media to intima
- Proliferation of SMC in intima
- Excess production of extracellular matrix (collagen and elastin)
- Enhanced lipid accumulation
Two most important causes of endothelial dysfunction are:
- Hemodynamic disturbances (hypertension)
- Hypercholesterolemia
Inflammation is also an important contributor

Macroscopic Features

Fatty streak: yellow discoloration with no bulging (small accumulation of macrophages with fat inside)
Simple plaque: raised yellow legion with irregular outline, large plaque present
Complicated plaque: can end up with calcification and hemorrhage

Microscopic Features

Early changes:
- Proliferation of smooth muscle cells
- Accumulation of foam cells
- Extracellular lipid
Later changes:
- Fibrosis
- Necrosis
- Cholesterol clefts
- +/- inflammatory cells
- Disruption of internal elastic lamina
- Damage extends into media
- Ingrowth of blood vessels
- Plaque fissuring

Clinical Complications

Progressive lumen narrowing due to high-grade plaque stenosis
Acute atherothrombotic occlusion - due to the activation of the coagulation cascade
Thrombus embolisation into the distal arterial bed
Ruptured abdominal atherosclerotic aneurysm
Myocardial infarction (heart attack), ischaemic heart disease (IHD)
Cerebral infarction (stroke)
Aortic aneurysms
Mesenteric occlusion
Peripheral vascular disease (gangrene of the legs)

Risk Factors

Non-modifiable risk factors:
- Age
- Gender (women protected relatively before menopause)
- Genetic predisposition
Modifiable risk factors:
- Hyperlipidaemia (high plasma cholesterol, LDL most significant, HDL protective)
- Cigarette smoking
- Alcohol (>5 units/day associated with increased risk of IHD)
- Infection (Chlamydia pneumoniae, Helicobacter pylori, Cytomegalovirus)
- Hypertension (mechanism uncertain, endothelial damage caused by raised pressure)
Diabetes mellitus: associated with high risk of cerebrovascular and peripheral vascular disease
Other risk factors:
- Lack of exercise
- Obesity
- Oral contraceptives
- Stress and personality type?

Prevention and Intervention

Prevention:
- No smoking
- Reduce fat intake
- Treat hypertension
- Not too much alcohol
- Regular exercise/weight control
Intervention:
- Stop smoking
- Modify diet
- Treat hypertension
- Treat diabetes
- Lipid-lowering drugs

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Description

This quiz covers the definitions and characteristics of arteriosclerosis, atherosclerosis, and related diseases affecting blood vessels. Learn about the differences and symptoms of these conditions.