MoD Session 6 Flashcards
What is atherosclerosis?
Thickening and hardening of arterial walls as a consequence of atheroma
What is atheroma?
Accumulation of intracellular and extracellular lipid in the intima and media of large and medium sized arteries
What is arteriosclerosis?
Thickening of the walls of arteries and arterioles usually from hypertension or DM
Is atherosclerosis or arteriosclerosis the same as atheroma?
Atherosclerosis
What is the normal arterial structure?
Endothelium Subendothelial connective tissue Internal elastic lamina Muscular media External elastic lamina Adventitia
How does the muscular media change as you move to arteries closer to the heart?
More elastin and less smooth muscle
What is the fatty streak in atheroma?
Lipid deposits in the intima which give rise to a yellow, slightly raised tissue
Why is the relationship of the fatty streak not direct to the atheroma?
Location of lesions in intima is not identical to the most severe atherosclerosis
What is the simple plaque in atheroma formation?
Individual lesions enlarge and coalesce to form widely distributed, irregularly outlined, raised yellow/white tissue
What is the complicated plaque in atheroma formation?
Haemorrhage into the thrombotic plaque by invading BV from the adventitia can cause it to rupture
Calcification of the plaque can further stiffen arterial walls
Aneurysm forms if there is a loss of elastic tissue
Where are common sites of atheroma?
Leg arteries Aorta - below superior mesenteric and above renal arteries Coronary arteries Carotid arteries Cerebral arteries
What does the severity of atheroma depend on?
Anatomical site
What are the three early microscopic features of atheroma?
Proliferation of smooth muscle cells
Accumulation of foam cells
Extracellular lipid
What are the later microscopic features of atheroma?
Fibrosis Necrosis Cholesterol clefts from crystals \+/- inflammatory cells Disruption of internal elastic lamina Damage through to media Ingrowth of BV Plaque fissuring
What leads to haemorrhage of plaque and subsequent occlusion of the artery?
Ingrowth of BV
How do cholesterol clefts appear histiologically?
As gaps as cholesterol dissolves during fixation
What is the structure of atheroma?
Endothelium
Smooth muscle cell
Lipid
Matrix
What is present in variable amounts in different atheromas?
Lipid - some hardly have any
What happens over time to an atheroma?
Matures by fibrosis
Replaces smooth muscle
What are the possible clinical effects of atheroma?
Ischaemic heart disease Cerebral ischaemia Mesenteric ischaemia Peripheral vascular disease Abdominal aortic aneurysm
Name some consequences of ischaemic heart disease.
Sudden death Myocardial infarction Angina pectoris Arrhythmias Cardiac failure
How is an old MI seen in the heart?
Pale tissue in heart wall
How does atheroma cause cerebral ischaemia?
Atheroma in carotid arteries causes turbulent flow –> thrombus –> embolism –> trapped in cerebral arteries
What are the sequelae of cerebral ischaemia?
Transient ischaemic attack
Cerebral infarction
Multi infarct dementia
What can be a further complication of cerebral infarction?
Can haemorrhage causing extra damage to tissues which is visible
Which artery is mesenteric ischaemia particularly seen in?
Superior mesenteric
What can mesenteric ischaemia cause?
Ischaemic colitis
Malabsorption
Intestinal infarction
Why is mesenteric ischaemia hard to recover in the elderly which is where it is most commonly seen?
Due to loss of GI function
Can the superior mesenteric artery be removed if it has become ischaemic?
Yes if BP is normal, no if BP is high
What is intermittent claudication?
Pain in calf upon exercise due to relative ischaemia which is relieved by rest but has a decreased claudication distance after
What is intermittent claudication a type of?
Peripheral vascular disease
What develops after intermittent claudication in the peripheral vascular disease pathway?
Ischaemic rest pain
What I s the final stage in the pathway of peripheral vascular disease?
Gangrene
What is Leriche syndrome?
Relative ischaemia in the iliac artery
What are the S/S of Leriche syndrome?
Pain in buttock
Impotence
Decreased/absent femoral pulse
What happens to the collateral vessels in Leriche syndrome?
They increase in number to maintain oxygen supply
How does atheroma lead to abdominal aortic aneurysm?
Atheroma causes loss of elastic tissue –> abnormal BV wall and flow –> thrombus
When does an abdominal aortic aneurysm rupture?
When the wall stretches and is not thick enough to support the increased diameter of the aorta
What can increase the risk of atheroma formation?
Oral contraceptives Age Gender Infection Hyperlipidaemia Cigarette smoking Hypertension DM Obesity Alcohol Stress and personality type Lack of exercise Soft water
Which gender has the higher risk of atheroma formation?
Male up until menopause
Which three pathogens have been linked with an increase in risk of atheroma formation?
Chlamydia pneumoniae
Helicobacter pylori
Cytomegalovirus
Which lipid is most significant in the risk of atheroma formation?
LDL
What is the suggested method by which cigarette smoking increases risk of atheroma formation?
Decreases prostaglandin 2 levels
Increases platelet aggregation
Causes hypercoaguable blood
What is a powerful risk factor for IHD?
Cigarette smoking
How may hypertension increase risk of atheroma formation?
Causes endothelial damage from high pressure
By how much does having DM increase the risk of IHD?
2x
What is lost in premenopausal women with DMD?
Protective effect against atheroma formation
Why are all sizes of BV compromised in DM?
Small vessels are compromised by arteriosclerosis
Other than IHD, what else does DM increase the risk of?
Cerebro-vascular disease
Peripheral vascular disease
How many units of alcohol per day increases IHD risk?
> 5 units per day
What effect can small amounts of alcohol have on the pathogenesis of atheroma formation?
May be protective
How is lipid transported in the blood?
On lipoproteins
What do lipoproteins carry?
Cholesterol
TAGs
What is the structure of a lipoprotein?
Hydrophilic outer phospholipid layer and apolipoprotein (A-E) layer