Atheroma Flashcards
What is an atheroma?
An accumulation of intracellular and extracellular lipid in the intima and media or large and medium sized arteries
Where do atheromas happen?
On the inside of the arteries, and spreads through the wall
Where is the fat deposited in an atheroma?
Can be on outside and inside wall
What is atherosclerosis?
The thickening and hardening of arterial walls as a consequence of atheoma
What is arteriosclerosis?
The thickening of walls of arteries and arterioles, usually as a result of hypertension or diabetes mellitus
What are the three macroscopic stages of an atheroma?
The fatty streak
The simple plaque
The complicated plaque
What causes the fatty streak?
Lipid deposits in the intima
How does the fatty streak appear macroscopically?
Yellow and slightly raised
What is the relationship between the fatty streak and atheroma?
Somewhat debatable- generally regarded as the precursor, but some people disagree
Why do some people dispute that the fatty streak is the precursor to atheroma?
Fatty streak may be seen in populations that don’t progress to atherosclerosis.
Some discussion about anatomical position of fatty streak compared to atherosclerosis
How does the simple plaque appear macroscopically?
Raised yellow/white, with an irregular outline
What happens as simple plaques develop?
They enlarge and coalesce, eventually becoming complicated
What occurs when a complicated plaque has formed?
Thrombosis
Why do complicated plaques lead to thrombosis?
Because the plaque has an irregular surface, which disrupts flow
What can happen to a complicated plaque?
It may rupture
Can be haemorrhage into plaque
Calcification
Aneurysm formation
What happens when a complicated plaque ruptures?
It releases substances that cause thrombosis
What are the common sites of atheroma?
Aorta, especially abdominal Coronary arteries Carotid arteries Cerebral arteries Leg arteries
What do early changes in atheroma include?
Proliferation of smooth muscle cells
Accumulation of foam cells and extracellular lipid, either in or between cells
The matrix of the cell may be substantially changed from normal
What do later changes in atheroma include?
Fibrosis
Necrosis
May be inflammatory cells
Cholesterol clefts
What are cholesterol clefts?
Where cholesterol crystals are laid down, there are needle shaped crystals of cholesterol that are soluble, so when solvents are used they are dissolved, leaving clefts
What is the eventual result of atheroma?
Disruption of the internal elastic lamina, with damage that extends into the media.
Ingrowth of blood vessels
Plaque fissuring
Why is there an ingrowth of blood vessels in atheroma?
Because whenever there is damage/inflammation, there is always a vascular response
What is plaque fissuring?
When the inside can move relative to the outside
What is the problem with plaque fissuring?
It allows for the release of materials that cause thrombosis
What are the clinical effects of atheroma?
Ischaemic heart disease
Cerebral ischaemia
Mesenteric ischaemia
Peripheral vascular disease
What is ischaemic heart disease?
The process of atheroma reducing flow of blood with or without thrombotic occlusion of arteries
What can ischaemic heart disease lead to?
Sudden death Myocardial infarction Angina pectoris Arrhythmias Cardiac failure
Why does ischaemic heart disease cause cardiac failure?
Causes scarring of the heart so it can’t function properly
What may be seen in cardiac failure caused by ischaemic heart disease?
Swollen arteries, scarring
What is cerebral ischaemia a result of?
Atherosclerosis in cerebral or carotid vessels
What can cerebral ischaemia lead to?
Transient ischaemic attack Cerebral infarction (stroke) Multi-infarct dementia Can undergo secondary haemorrhages Abdominal aortic aneurysm
When may someone undergo secondary cerebral haemorrhages?
Where dying tissues start to degenerate
How does mesenteric ischaemia often present?
Rectal bleeding
Maybe abdominal pain
What can mesenteric ischaemia lead to?
Ischaemic colitis
Malabsorption
Intestinal infarction
What is an acute intestinal infarction more likely to be caused by?
Thrombus or embolus
Where are intenstinal infarctions most common?
In superior mesenteric artery
What is peripheral vascular disease?
Atherosclerosis affecting vessels supplying the legs
What can peripheral vascular disease lead to?
Intermittent claudication
Leriche syndrome
Ischaemic rest pain
Gangrene
What is intermittent claudication?
Pain in legs because of reduced blood supply