Atheroma Vascular Disease Flashcards
What is arteriosclerosis?
Thickening and hardening of wall of an artery
Arteriolosclrosis
Thickening and hardening of the wall of an arteriole
Atheroma
Important disease of large and medium arteries
Initially disease of tunica intima, later affects tunica media
Atherosclerosis
Arteriosclerosis due to atheroma
What is the most common cause of thickening and hardening of the Walls in large and medium arteries
Atheroma
What is the most common cause of thickening and hardening of the walls of small arteries and arteriolar
High blood pressure
Changes in small arteries due to hypertensive arteriosclerosis
Hypertrophy of media
Fibroelastic thickening of intima
Elastic lamina reduplication
Changes in arterioles due to hypertensive arteriosclerosis
Replacement of wall structures by amorphous hyaline material
Consequences of hypertensive vascular changes
Reduction of vessel lumen - reduced flow - ischaemia in supplied tissue
Increased rigidity of vessel wall - loss of elasticity and contractility - unresponsive to normal vessel control agents eg. vasodilators
Do atheromas occur in high or low pressure systems?
High
Systemic arterial system, not venous
Characteristic of atheroma
Ubiquitous
Very mild in young people
Worsening with age
Visually, how does atheroma develop?
Fatty streak
Lipid plaque
Fibrolipid plaque
Complicated atheroma
Stages of atheroma development?
LDL enter through damaged endothelium
Lipids are phagocytosed by macrophages in intima to make raised fatty streak - accumulation of the macrophages
Some lipid is released by macrophages - lipid plaque
Macrophages secrete cytokines which stimulate myofibroblasts to secrete collagen
Early damage of elastic lamina and media
Collagen covers plaque surface - fibrolipid plaque
Media thins with replacement of muscle fibres by collagen
Lipids in intima become calcified
Surface of fibrolipid plaque ulcerates
Thinning of media leads to weakness and inelasticity - complicated atheroma
What will eventually occur to the lipids?
Degenerate and calcium deposited
Calcified
Increase rigidity of blood vessel
Risk factors of atherosclerosis
Smoking
Fast food
High BMI
Low activity
Complications of atheroma
Expansion of intima -> reduction of size of lumen -> reduced blood flow & hence oxygenation of tissue
Ulceration of atheromatous intima -> predisposition to thrombus formation -> vessel occlusion
Plaque fissure formation & haemorrhage
Replacement of muscle & elastic fibres in media -> loss of elasticity -> thinning and stretching (ANEURYSM)
What will reduction of lumen lead to?
Reduced blood flow, reduced oxygenation of tissues, therefore Ischaemic damage to tissues
Atheroma in coronary arteries
Angina - chest pain
Atheroma in leg arteries
Intermittent claudication
Atheroma in mesenteric arteries
Ischaemic colitis - can cause extensive bleeding of bowel
Or haemorrhage
Atheroma in cerebral and vertebral arteries
Cerebral ischaemic events (stroke)
What may occur is reduction in flow is severe enough?
Tissue may die due to hypoxia - infarction
How can an atheroma cause thrombosis
Damaged and ulcerated endothelium may lead to formation of thrombus
May complete occlusion of vessel lumen
How can an atheroma cause plaque fissures
Blood sleeps into atheromatous plaque and expands it
Or blood seeps into plaque and undergoes thrombosis
What is an aneurysm
Abnormal permanent focal dilatation of an artery
Types of aneurysm
Syophilitic
Development in cerebral vessels
Dissecting aneurysms of thoracic aorta
Mycotic aneurysms
Main types of aneurysms
Saccular
Fusiform
Dissecting
How can damage to media lead to aneurysm?
Enlarging intimal atheroma plaque leads to atrophy of media
Muscle and elastic fibres in media replaced by collagen
Collagen strong but neither contractile or can do elastic recoil, therefore:
Each systolic pulse, wall of artery stretches and thins
Common aneurysms
Atheromatous aortic
Aortic dissecting
Cerebral ‘berry’
Cause of uncommon mycotic aneurysm
Endocarditis (infection of heart valve) Bacterial septicaemia Infection of arterial wall Weakening and dilatation Risk of bleed
