Atherosclerosis Flashcards
(28 cards)
Define ischaemia
Ischaemia:
* Inadequate blood supply to an organ or part of the body.
* Starves the cells of oxygen
What are the recommended levels of cholesterol?
Recommended levels of cholesterol
Total cholesterol: <200mg/dl
HDL: > 40mg/dl
Triglycerides: < 150mg/dl
LDL: <100mg/dl
Where is the intima found?
The intima is found just below the endothelial cells
What is the LDL target for someone with Coronary Artery Disease and Diabetes?
The LDL target for someone with Coronary Artery Disease and Diabetes: <70 mg/dl
Define atherosclerosis
Atherosclerosi:
* Chronic inflammation of the intima of large blood vessels
* Characterized by fibrofatty plaque formation (atheroma)
Define arteriosclerosis
Arteriosclerosis:
* Hardening/stiffening of the arteries
* Thickening of the arterial walls
* Loss of elasticity of the arterial walls
What are the key processes that cause atheroma development?
Key processes that cause atheroma development:
1. Lipid accumulation (LDL)
2. Inflammation
3. Damage by free radicals
What can atherosclerosis lead to?
Atherosclerosis can eventually lead to blockage of the coronary arteries and a heart attack.
What triggers the development of atherosclerosis?
Atherosclerosis development is triggered by endothelial dysfunction which starts as a response to chronic endothelial injury.
Atherosclerosis process in 5 stages
Atherosclerosis process in 5 stages
1. Chronic endothelial injury
2. Endothelial dysfunction
3. Initiation of fatty streak: smooth muscle emigration from the media to the intima. Macrophages activated
4. Fatty streak development: macrophages and smooth muscle cells engulf oxidized LDL (lipid)
5. Fibro-fatty atheroma: Smooth muscle proliferation, collagen and other extracellular matrix deposition, extracellular lipid
Which treatments are available for atherosclerosis?
Atherosclerosis treatments:
1. Stenting
2. Angioplasty
3. Bypass surgery
4. Statins
Which things can prevent atherosclerosis?
Atherosclerosis prevention:
1. Regular medical check ups
2. Good blood pressure control
3. Good cholesterol control
4. Stop smoking
5. Regular exercise (30 minutes most days of the week)
6. Maintain a healthy weight
7. Eat a heart-healthy diet, low in saturated fats
8. Manage stress
Uncontrollable atherosclerosis risk factors
Uncontrollable atherosclerosis risk factors:
* Sex
* Hereditary/ genetics
* Race
* Age: Older age
* Post-menopausal state: Hormonal changes
What do the conditions in the intimal layer of the arteries favour?
The conditions within the intimal layer of the arteries favours oxidation of LDL-cholesterol by reactive oxygen species.
What does endothelial inflammation attract?
Endothelial inflammation attracts monocytes
Describe a normal arterial wall
A normal arterial wall:
* Single layer of endothelial cells: tightly packed, forms a barrier
* Intima/ intimal layer: inner most layer
* Media: Smooth muscle cells, elastin fibres and collagen
* Aventitia: Outside layer composed of connective tissues, nerves. Keeps blood vessels in place.
* Basement membrane
What can cause endothelial injury?
Things that can cause endothelial injury:
* Hyperlipidaemia
* Hypertension
* Smoking
* Homocysteine
* Hemodynamic factors
* Toxins
* Viruses
* Immune reactions
Summarise the development of atherosclerosis
- Damage is caused to the endothelium: smoking, hyperlipidaemia, hypertension, viruses
- Theres increased permeability
- Monocytes, LDL, platelets are recruited to the damaged area/ up regulation of endothelial and leukocyte adhesion
- Monocytes differentiate into Macrophage diapedesis: blood cells (WBC) move through capillary walls
- LDL enters and is oxidized
- Macrophages engulf LDL and foam cells are formed
- Smooth muscle cells are recruited and proliferate
- Formation and organization of arterial thrombi
Explain the complications of atherosclerosis
Generalised
Narrowing/Occlusion
Rupture
Thromboembolism
Leading to specific problems:
Heart attack (myocardial infarction) and stroke (cerebral infarction)
Aortic aneurysms
Peripheral vascular disease
Gangrene – tissue infarction.
Kidney failure – Kidney infarction.
Explain the management and treatment for atherosclerosis
Stenting, bypass surgery, lifestyle modifications, angioplasty, statins
Stenting
Stenting
Temporary measure
* a stent is introduced into a blood vessel on a balloon catheter and advanced into the blocked area of the artery
* the balloon is then inflated and causes the stent to expand until it fits the inner wall of the vessel, conforming to contours as needed
* the balloon is then deflated and drawn back
* The stent stays in place permanently, holding the vessel open and improving the flow of blood.
Angioplasty
Angioplasty:
* Compresses plaque against artery wall
* a balloon catheter is passed through the guiding catheter to the area near the narrowing.
* A guide wire inside the balloon catheter is then advanced through the artery until the tip is beyond the narrowing.
* the angioplasty catheter is moved over the guide wire until the balloon is within the narrowed segment.
* balloon is inflated, compressing the plaque against the artery wall
* once plaque has been compressed and the artery has been sufficiently opened, the balloon catheter will be deflated and removed.
Bypass surgery
Bypass surgery:
* healthy blood vessel is removed from leg, arm or chest
* blood vessel is used to create new blood flow path in the heart. The “bypass graft” enables blood to reach the heart by flowing around (bypassing) the blocked portion of the diseased artery. The increased blood flow reduces angina and the risk of heart attack.
Statins
Statins: reduces cholesterol production
* Statins inhibit HMG CoA reductase* in the hepatocytes A key enzyme in the pathway that synthesises cholesterol
* Inhibiting HMG CoA reductase reduces cholesterol production
* Low levels of cholesterol increase the expression of LDL receptors
* This increases the uptake of LDL into the hepatocytes
* Cholesterol levels in the blood fall
- 3-hydroxy-3-methylglutaryl coenzyme-A reductase
- 30 minutes of exercise would be recommended first to increase blood flow
- Examples: atorvastatin, fluvastatin, pravastatin, rosuvastatin and simvastatin.
- Side effects: myostitis (muscle inflammation), headache, GI disturbance
- bedtime administration as most cholesterol synthesized at night
- Conta-indicated: liver disease, pregnancy, breast feeding
