Vascular disease: Atheroma and its complications Flashcards
What is arteriosclerosis
Thickening and hardening of the wall of an artery
What is arteriolosclerosis
Thickening and hardening of the wall of an arteriole
What is an atheroma
AN important disease of large and medium arteries
What is atherosclerosis
Arteriosclerosis due to atheroma
What is the most common cause of arteriosclerosis in large and medium arteries
Atheroma
What is the most common cause of thickening and hardening of the walls of small arteries and arterioles
High blood pressure
What are the three changes that occur in hypertensive arteriosclerosis
- HYpertropy of media
- FIbroelastic thickening of intima
- Elastic lamina reduplication
In hypertensive arteriosclerosis, what are the wall structures replaced by
Amorphous hyaline material
What is the consequence of a reduction of vessel lumen because of hypertensive vascular changes
Reduced flow which means there is ischaemia in supplied tissue
What is the consequence of increased rigidity of vessel wall because of hypertensive vascular changes
Loss of elasticity and contractility. Means it is unresponsive to normal vessels; control agents like vasodilators
Where does an atheroma occur in
High pressure systems
Where does an atheroma not occur in
Venous system because it is not high pressure
What is an atheroma initially a disease of
-What does it later affect
Tunica intima
-Tunica media
What are the four recognisable stages of the development of an atheroma
- Fatty streak
- Lipid plaque
- Fibrolipid plaque
- Complicated atheroma
Stages of development of an atheroma
1) Blood lipids enter intimate through damaged endothelium
2) Lipids are phagocytosed by macrophages in intimate to make raised fatty streak
3) Lipid plaque is released by macrophages
4) Macrophages secrete cytokines which stimulate my-fibroblasts to secrete collagen
5) Early damage to elastic lamina and media
6) COllagen cover plaque surface (fibrilipid plaque)
7) Media thins, with replacement of muscle fibres by collagen
8) Lipids in intimate become calcified
9) Surface of fibro-lipid plaque ulcerates
10) Thinning of media leads to weakness and inelasticity (complicated atheroma)
What is the complication of an expansion of intima
Reduction in the size of the lumen so there is less blood flow and hence oxygenation of tissue
What is the complication of an ulceration of atheromatous intima
Predisposition to thrombus formation
Vessel gets occluded
what is the complication of replacement of muscle and elastic fibres in media
There is loss of elasticity so there is thinning and stretching (leads to an aneurysm)
What does an atheroma in a leg artery cause
Intermittent claudication (pain when walking and exercising in calves, but is relieved by resting)
What does an atheroma in the mesenteric arteries cause
Ischaemic colitis (inflammation of large intestine because of inadequate blood supply)
How does damage to media lead to an aneurysm
- Enlarging intimal atheroma plaque leads to atrophy of the media
- MUScle and elastic fibres in media are replaced by collagen
- Collagen is strong but is neither contractile nor capable of elastic recoil
- Therefore with each systolic pulse, the wall of an artery stretches and thins, particularly when blood pressure is elevated
What is an aneurysm
Abnormal permanent focal dilatation of an artery
What is the most common type of aneurysm
In abdominal aorta
Three type of aneurysms
- Saccular
- Fusiform
- Dissecting
What is a mycotic aneurysm mostly caused by
Endocarditis (infection of heart valve)
Bacterial septicaemia
Infection of arterial wall
Weakening and dilatation is an aneurysm
