PATH 12 – ATHEROSCLEROSIS Flashcards
What is atherosclerosis
Atherosclerosis and atheroma are used interchangeably
‘Hardening of the arteries’
atherosclerosis as a chronic inflammatory response in response to endothelial injury.
Deposition of atheroma occurs on larger elastic or muscular arteries (not veins)
Note that ;
Atheroma is a fibrolipid plaque
Atherosclerosis is hardening of arteries due to plaque.
What is the normal vasculature
- Arteries (elastic, muscular,distributing, small)
- Arterioles
- Capillaries
- Venules
- Veins
What are the functions of vascular Endothelial Cells?
Serve as semipermeable membrane.
Maintain blood tissue interface.
Modulate vascular tone and blood flow.
Regulate immune and inflammatory reactions
Alter flow and leakage permeability
Modify lipoproteins in arterial wall → atheroma.
What are the common common clinical consequences of Atherosclerosis?
Myocardial infarction / ischaemic heart disease.
Cerebral infarction (stroke).
Peripheral vascular disease.
Aortic aneurysms.
Mesenteric occlusion – ischaemic bowel.
Ischaemia/Infarction can occur from plaque occluding artery or from an embolus from the plaque.
Explain Atherosclerosis pathogenesis
1Chronic endothelial injury → thrombotic potential. Endothelila dysfunction increases permeability and leukocyte adhesion.
- Accumulation of lipoprotein (LDL with high cholesterol) in vessel wall lipid sleak into intima
- Monocytes and leukocytes intima of blood vessel → transform to macrophages lipids are oxidised and consumed by macrophages via scavenger receptors, resulting in foam cells
- Factors from platelets and macrophages cause migration of smooth muscle cells from media of artery to intima.
- Smooth muscle cells collagen accumulation giving a fibrolipid plaque i.e. atheroma
How often does Atheroma occur in Veins and why?
Rarely
Why not? The main factor to the endothelial damage is high pressure, which is not usual in the venous system (elastic wall is compliant)
Differentiate Atheroma and Atherosclerosis
Atheroma is a fibrolipid plaque while Atherosclerosis is the thickening of the wall due to atheroma.
Give the risk factors of atherosclerosis.
Age
Gender
Genetics
-Familial predisposition to atherosclerosis is most likely polygenic.
Hyperlipidaemia, failure to clearance of low density lipoproteins.
Hypertension around branches.
Cigarette smoking.
Smoking one or more packs of cigarettes per day for several years increases the death rate from IHD by up to 200%.
Diabetes mellitus.
State the distribution of atheroma in the human body.
Abdominal aorta, esp around ostia of its major branches. Why around ostia? Turbulent blood flow
Coronary arteries.
Popliteal arteries.
Descending thoracic aorta.
Internal carotid and arteries of Circle of Willis.
Often widespread within an individual.
“Atheropath”
What is Aneurysm
A localised abnormal dilation of a blood vessel.
When aneurysm involves intact attenuated arterial wall eg. atherosclerotic aneurysm/ syphilitic aneurysm
TRUE/FALSE
True - bounded by arterial wall components or the attenuated wall of the heart.
When aneurysm involves intact attenuated arterial wall eg. atherosclerotic aneurysm/ syphilitic aneurysm
TRUE/FALSE
True - bounded by arterial wall components or the attenuated wall of the heart.
Pseudo-aneurysm defect in the vascular wall leading to an extravascular hematoma that freely communicates with intravascular space “pulsating hematoma”.
TRUE /FALSE
False - a breach in the vascular wall leading to an extravascular hematoma that freely communicates with the intravascular space e.g. Following trauma
What are the types of Aneurysm
1.Saccular
Spherical outpouchings (involving only a portion of the vessel wall)
- often contains thrombus
2.Fusiform
Diffuse, circumferential dilation of a long vascular segment
- Dissection aneurysm
- False aneurysm
What weakens wall and causes aneurysms?
>Atherosclerosis >Congenital defects – berry aneurysm in Circle of Willis >Infections (mycotic aneurysm) >Trauma >Cystic medial degeneration >Systemic diseases, e.g. vasculitis >Syphilitic (luetic)
Describe Atherosclerotic Aneurysms
Most frequently in the abdominal aorta (AAA). [saccular or fusiform]
Common in iliac arteries, the arch, and descending parts of the thoracic aorta can be involved.
What is Abdominal Aortic Aneurysm
Usually positioned below the renal arteries and above the bifurcation of the aorta.
Types: saccular or fusiform.
Can be up to 15 cm in greatest diameter and of variable length.
The risk of rupture is directly related to the size of the aneurysm > 5 cms.
Important clinical factor affecting aneurysm growth is blood pressure.
What are the two most important disorders that predispose to aortic aneurysm?
- Atherosclerosis e.g Abdominal Aortic Aneurysm.
2. Hypertension e.g aneurysm of ascending aorta.
What are the clinical Consequences of Abdominal Aortic Aneurysms?
> Rupture into the peritoneal cavity or retroperitoneal tissues with massive, potentially fatal, haemorrhage.
Obstruction of an artery (iliac, renal, mesenteric, or vertebral branches that supply the spinal cord) leading to ischemic tissue injury or infarction
Embolism from atheroma or mural thrombus
Impingement on an adjacent structure, such as compression of a ureter or erosion of vertebrae
Presentation as an abdominal mass (often palpably pulsating) that simulates a tumour.
How do we manage atheroma?
>Control hypertension, hyperglycaemia in diabetic, stop smoking >Reduce obesity >Exercise >Checking on diet >Hyperlipidaemia (statins)
Thoracic Aortic dissection is related to Atheroma? TRUE /FALSE
False.
What is Thoracic Aortic dissection
Tear in the intima allows dissection of blood between and along the laminar planes of the media, resulting in the formation of a blood-filled channel within the aortic wall.
Can rupture outward, causing massive haemorrhage.
May or may not be associated with dilatation/aneurysm of the aorta (Avoid term dissecting aneurysm).
What are the causes of Thoracic Aortic dissection?
More than 90% of dissections occur in men between the ages of 40 and 60 with antecedent hypertension.
Systemic or localised abnormality of connective tissue that affects the aorta (eg. Marfan syndrome).
Iatrogenic, as a complication of arterial cannulation
What are the clinical symptoms of Aortic dissection?
Sudden onset of excruciating pain, usually beginning in the anterior chest, radiating to the back, and moving downward as the dissection progresses
Complications depend on the level of the aorta affected
Most serious complications occurring from the aortic valve to the arch haemopericardium
Main cause of death is rupture of the dissection outward.
What is arterial dissection?
Condition that comes by when blood enters the arterial wall itself as a hematoma dissecting between its layers.
Define aortitis
inflammation of the aorta
What are the cause of Aortitis
Giant cell arteritis
Other arteritis
Rheumatoid arthritis
Syphilis
What is the difference between atheroma, atherosclerosis and arteriolosclerosis?
> Atheroma is a Fibrolipid plaque
Atherosclerosis is Atheroma of larger arteries with fibrosis/narrowing
Arteriolosclerosis is the narrowing of small arterioles due to hypertension
How does age increase the chances of suffering from atherosclerosis?
Death rates from IHD rise with each decade
Between ages 40 and 60 the incidence of myocardial infarction increases fivefold
How does gender increase / decrease the chances of one suffering from atherosclerosis?
Other factors being equal, males are more prone to atherosclerosis
After menopause, the incidence of atherosclerosis-related diseases increases in women probably owing to a decrease in natural oestrogen levels.
Explain how Hyperlipidaemia affects atherosclerosis
Hyperlipidaemia, failure to clearance of low density lipoproteins.
Low-density lipoprotein (LDL) delivers cholesterol to peripheral tissues.
High-density lipoprotein (HDL) mobilizes cholesterol, transporting it to the liver for excretion in the bile.
High dietary intake of cholesterol and saturated fats, (egg yolk & animal fats) raises the plasma cholesterol level.
Explain how diabetes mellitus increases the risk of suffering from atherosclerosis.
Induces hypercholesterolemia and a markedly increased predisposition to atherosclerosis.
Incidence of myocardial infarction is twice as high in diabetics as in non-diabetics.
100-fold increased risk of atherosclerosis-induced gangrene of the lower extremities.
