Atherosclerosis Flashcards
What is the definition for atherosclerosis?
The accumulation of intracellular and extracellular lipid in the intima and media of large and medium sized arteries
What is the definition of an arteriosclerosis?
The thickening of the walls of arteries and arterioles usually as a result of hypertension or diabetes mellitus
What are the risk factors for the development of atherosclerosis?
Age Gender Genetics Hyperlipidaemia Cigarettes smoking Hypertension Diabetes mellitus Alcohol Infection
What might atherosclerosis of the coronary artery cause? And why?
Angina or heart failure due to reduced blood flow to myocardium.
Coronary thrombosis commonly occur over atheromatous plaques and leads to an MI
What is atherosclerosis of the carotid arteries often associated with?
Stroke due to the initial formation of thrombus over the plaque which later embolisms to the cerebral arteries
Name the cells types that are involved in atherogenesis
Endothelial cells Platelets Smooth muscle cells Macrophages Lymphocytes Neutrophils
What types of plaques (macroscopic features) that you can get with atherosclerosis?
- Fatty streak
- Simple plaque
- Complicated plaque
What is a fatty streak? How does it appear?
Lipid deposits in intima
Yellow and slightly raised
*the relationship to atherosclerosis somewhat debatable
What does a simple plaque look like?
Raised yellow/white appearance
Irregular outline
Widely distributed
Enlarged and coalesce
- fairly discrete but becomes larger and colourless
Once a plaque has formed there are complications that can occur, what are these?
- A thrombosis
- Haemorrhage into plaque (causing expansion and potentially compromising the lumen)
- Calcification (leads to crunchy artery)
- Aneurysm formation
What are the common sites for atheroma to form?
- Aorta (especially abdominal)
- Coronary arteries
- Carotid arteries
- Cerebral arteries
- Leg arteries
What is the normal arterial structure (listed inside to out)?
Endothelium Sub-endothelial connective tissue Internal elastic lamina Muscular media External elastic lamina Adventitia
What are the early microscopic changes that occur during the formation of an atherosclerosis?
- Proliferation of smooth muscle cells
- Accumulation of foam cells
- Extracellular lipid
What are the later microscopic changes that occur during the formation of an atheroma?
- Fibrosis (fibroblasts move in and proliferate)
- Necrosis
- Cholesterol clefts (extracellular lipid is dissolved away during preparation of microscopic slide so we see empty clefts)
- +/- inflammatory cells
- Disruption of internal elastic lamina
- Damage extends into media (elastin)
- In growth of blood vessels
- Plaque fissuring (allows blood into plaque- expansion and exposes the plaque to substances that will form thrombosis)
What are the clinical effects of atherosclerosis?
Ischaemic heart disease:
- sudden death
- myocardial infarction
- angina pectoris
- arrhythmias
- cardiac failure
Cerebral ischaemia:
- transient ischaemic attack (mini stroke, will resolve symptoms within 24 hrs)
- cerebral infarction (actual stroke, uni lateral symptoms)
- multi-infarct dementia
Mesenteric ischaemia (Gut):
- ischaemic colitis
- malabsorption (small bowel)
- intestinal infarction
Peripheral vascular disease:
- intermittent claudication (pain in calves)
- Leriche syndrome (pain in buttocks)
- ischaemia rest pain
- gangrene
What role does gender play in atherosclerosis?
-women protected relatively before menopause, presumed hormonal basis
What role does hyperlipidaemia play in atherosclerosis?
- high plasma cholesterol associated with atherosclerosis
- LDL most significant
- HDL protective (removes lipids in blood)
What role can genetics play in atherosclerosis?
There are genetic variations in ApoE
Polymorphisms of genes involved can lead to at least 6 Apo E phenotypes which can be used a risk markers.
Certain types of Apo E can increase one’s likelihood of getting atheromas
You might also have familial hyperlipidaemia
What are the physical signs of hyperlipidaemia?
- Arcus (ring around cornea)
- Tendon xanthomas (nodules on tendons)
- Xanthelasma (yellowish collection of cholesterol underneath the skin-usually on or around the eyelids)
What role does hypertension play in atherosclerosis?
Strong link between IHD and high systolic/diastolic blood pressure
*assumed that the high pressure damages the endothelial- which allows the formation of an atheroma
What role does diabetes mellitus play in atherosclerosis?
Increases risk of ischaemic heart disease, can also cause cerebrovascular and peripheral vascular diseases which lead to atheroma formation
The protective effect in premenopausal women is lost somewhat if they are diabetic
Name some organisms that have been associated with the formation of atheromas
Chlamydia pneumoniae
Helicobacter pylori
Cytomegalovirus
List the 4 theories that could explain how atherosclerosis comes about
- Thrombogenic theory
- Insulation theory
- Monoclonal hypothesis
- Reaction to injury hypothesis
Describe the cellular events leading to the formation of atherosclerotic lesions
- Chronic endothelial injury
- Endothelial dysfunction with platelet adhesion and monocytes accumulation with release of growth factors and cytokines
- Smooth muscle emigration from media into intima
- Macrophages and smooth muscle cells engulf lipid to form foam cells
- Smooth muscle proliferation, collagen and matrix deposition, extracellular lipid deposition, neovascularisation
