Circulatory disorders Flashcards
What are the specific problems of plaque formation?
- Myocarical and cerebral infarcts
- Aortic aneurysms
- Peripheral vascular disease
What is pulmonary embolism?
From venous emboli that pass through the right side of the heart into the pulmonary artery
What 3 alteration to blood constituents cause a thrombus?
1) Increase in cells/platelets and plasma proteins (solid)
2) Decrease in fluid (eg. after severe burns)
3) Blood becomes hypercoagulable (more likely to clot)
What makes up a thrombus?
- Endothelial cells
- Platelets (fragments of cells)
- Coagulation cascade, leading to the production of fimbrin
How does damage to endothelial lining cause a thrombus?
- Damage exposes highly thrombogenic sub epithelial tissue (due to physical, chemical or inflammatory disturbances)
- Balance between release of thrombogenic and anti-thrombogenic stimuli is shifted
What is CHD also known as?
Ischaemic heart disease
In a consecutive clot, what can stabilize the thrombus?
- The blood incoming from the end of a tributary
- Platelets and fibrin
- Can reattach the clot to the vessel wall, permitting further propagation
What are the disadvantages of drug-eluting stents?
- Antiproliferative drugs which are released from the stent prevent the proliferation of endothelial cells
- Not smooth surface
- Platelet aggrucation
- Thrombus formation
(Endothelial cells needed to grow over stent to produce smooth surface for blood flow)
How does turbulence cause a thrombus and where does it occur?
- Occurs around the branches of arteries etc, where different blood flows are hitting each other
- Alteration to the normal, lamellar flow pattern
- Can damage the endothelium
What is a thrombus?
- A solid mass of BLOOD formed within the cardiovascular system
- A ‘clot’
What is restenosis?
The recurrence of abnormal narrowing of an artery or valve after corrective surgery (stenting)
- Smooth muscle cells grow over the stent
What is ATHEROsclerosis?
- Fatty deposits (lipid and cellular debry)
- Disease of the tunica INTIMA
Damage to the endothelial lining which may lead to:
- Narrowing of the vessels
- Obstruction
- THROMBOSIS
What is ‘thrombosis’ and how is it different to a ‘thrombus’?
- Thrombosis is the presence of a clot within a blood vessel
- The clot itself is called the thrombus
What is ARTERIOsclerosis?
Disease of the tunica MEDIA which may lead to:
- Increased wall thickness
- Decreased wall elasticity
- Leads to hypertension (smaller lumen)
What 3 things do the consequences of vascular occlusion depend upon?
- Type of tissue involved (artery or vein)
- How quickly the occlusion occurs (sudden or gradual)
- The availability of collateral circulation (alternative circulation)
What is percutaneous coronary inverventions?
A combination of:
- Angioplasty (balloon opening a blocked vessel
- Stenting (wire mesh)
Maintains lumen size
What causes an arterial thrombus?
- Middle age, elderly
- May have underlying circulatory disorders
- Increase risk by diabetes smoking
What are the MODIFIABLE risk factors of CHD?
Strong association
- Smoking
- Diabetes mellitus
- Obesity
- Hypertension
- Hyperlipidaemia
Weak association:
- Lack of excersice
- High alcohol
- Type A personality (more prone to stress)
- Soft water
What attaches a blood clot to the endothelial wall?
Fimbrin and platlets
What is embolisation?
Carrying of fragments of thrombus into the general circulation, when there is no tributary to able a consecutive clot to be reattached to the blood vessel wall
Normally, where does the fastest blood flow?
In the middle of the bulk of blood
What can 4 things can vascular occlusion be a result of?
- Thrombosis (blood clot)
- Embolism (detached blood clot, can move)
- Atherosclerosis (fatty deposits)
- External compression (eg during an accident)
What is angina?
The pain of CHD, caused by narrowing of the arteries
What are the major components of an atheromatous plaque?
1) Fibrous cap
- Smooth muscle cells
- Collagen
- Elastin
(New cell layer)
2) Cellular layer
- Macrophages, T cells
- Smooth muscle cells
3) Necrotic core
- Lipid and cellular debry
- Cholesterol clefts
- Foam cells
4) Calcification
- Deposition of calcium rich material
What are the generalised consequences of plaque formation?
- Narrowing and occlusion
- Rupture
- Emboli
- Calcification
What causes CHD?
1) Blockage in coronary artery
2) Decrease in oxygenated blood flow
- CO poisoning
- Anemia
- Hypotension
3) Increased demand
- Hypertrophy
What are foam cells?
- Fat-laden M2 macrophages that serve as the hallmark of early stage atherosclerotic lesion formation
- Uptake lipids and undergo cell death
What happens in a heart attack?
Lack of nutrients and oxygen to the cardiac muscle, leading to cardiac muscle cell death
What causes CHD?
- Narrowing of the CORONARY ARTERIES
- Can lead to a myocardial infarction if a complete blokage
Why does vascular occlusion have a higher consequence in arteries than veins?
Arteries have less alternative routes than veins
How can thrombus formation be described?
By Vircholu’s triad
1) Alteration to blood constituents
2) Damage to endothelial lining
3) Altered blood flow
What is arteriogenesis?
- Collateral vessel formation (birth of a new artery)
How can you overcome restenosis?
Drug-eluting stents
- Given with anti-platelet therapy to prevent aggrucation
What causes an atheromatous plaque?
Aysymptomatic small fatty streak –> atheromatous lesion –> plaque
What is the process of atheromatous plaque formation?
1) Endothelial cell activation and dysfunction, promoting lipid accumulation
2) Inflammatory response and immune cell recruitment
- Foam cells
3) Recruitment and proliferation of smooth muscle cells and extracellular matrix synthesis
What are the FIXED rick factors of CHD?
- Age
- Male
- Family history
What causes a venous thrombus?
- May be any age
- Due to prolonged periods of immobility
What are ‘lines of Zahn’?
- Banding of a venous thrombus
- Formed by alternating red and white cell and platelet deposits
- Orientated along axis of blood flow
- Light = platelets and fibrin
- Dark = red and white blood cells
What are ‘consecutive clots’?
- Unstable clot
- Formed when the lumen is occluded
- Slow flow
- No lines of Zahn and no new platelets
- Weakly attached to the wall and can easily be dislodged
How does stasis cause a thrombus and where does it occur?
- Occurs in venous thrombus
- Speed of flow is reduced
- Results in a change of thrombogenic and anti-thrombogenic stimuli
- Thrombus occurs in the VALVE POCKET, where the platelets adhere to the surface
What is systemic embolism?
From the arterial system to a variety of organs
