Chapter 8 Stroke Flashcards
What is cerebral circulation?
Blood supply to the brain
What are the two main arteries that supply blood to brain?
1) internal Carotid arteries
2) Vertebral arteries
whats the other name for internal carotid arteries?
Anterior circulation
What is the other name for vertebral arteries?
Posterior circulation
where does the major artery systems ( anterior and posterior) connected?
Circle of Willis
what is circle of willis?
Interconnects both major artery systems ICA ( anterior) and VA (posterior)
what does brain requires?
Brain requires continuous flow of blood for glucose and oxygen
without blood flow, how long til metabolic disruption occurs?
- 30 seconds
without blood flow, how long till metabolism stops?
2 minutes
How long does cellular death occur without blood flow?
5 minutes :(
Blood flow to the brain is affected by? (3)
- Systemic BP
- Cardiac output ( how much blood the heart pumps per minute)
- Blood viscosity ( thickness of blood )
What is collateral circulation
- May develop in situations of low cerebral blood flow if the blood supply is cut off to one area of the brain due to blockage it can sometimes receive blood from different blood vessels
- Varies depending on individual patient and they develop to sustain perfusion when primary route are blocked.
What is Stroke?
Occurs when there is inadequate blood flow to the brain (ischemia) or hemorrhage into the brain
Stroke results in what?
results in death of brain cells
What area will be impaired or loss due to stroke? (3)
Functions such as movement, language, sensation that were controlled by the area of damage will be impaired or loss.
What is the leading cause of disability in Canada for adults
Stroke
Stroke is the __ leading cause of death in Canada
3rd
what is the major cause of stroke?
Atherosclerosis
What is Atherosclerosis
- Hardening and thickening of artery
Atherosclerosis is characterized by
- Characterized by deposits of lipids within intima of artery
- Soft deposits that hardens as we get older
What is the steps of Atherosclerosis?
1) Chronic endothelial Injury ( Damage endothelium)
2) Fatty streak
3) Fibrous Plaque
4) Complicated lesion
What causes endothelial Injury (Damaged endothelium) (7)
- Hypertension
- Tobacco use
- Hyperlipidemia
- Hyperhomocysteinemia
- Diabetes
- Infections
- Toxins
Explain what happens in fatty streak
- Lipids accumulate and migrate into smooth muscle cells
- Lipids comes and oxidize
- Ingested by macrophages becoming foam cells
- Foam cells creates fatty streaks
Fibrous Plaque
- Lipids and platelets stimulate arterial wall thickening
- Collagen covers fatty streak called fibrous plaque
- Vessels diameter becomes narrower
- Risk for plague rupture
Complicated lesions
- If plaque ruptures, the platelets aggregates to site leading to clot.
- Thrombus formation
- It can also break off and travel
Stroke Risk Factors
See Notes theres too much :(((
Which gender have more higher risk?
Men
How is age a risk factor?
Increase in age means higher risk for stroke due to effect of arteries. Over 65 years but can happen at any age.
How is genetics a risk factor?
- High cholesterol can be genetics
- Stroke family history have higher risk factor
How is ethnicity a risk factor?
- African, south asian, hispanic, Indigenous population
How is hypertention a risk factor?
- Highest risk factors
- increase pressure against intima of artery causes sheering stress leading to injury. Weakens artery which can cause clotting and bleeding.
What BP is high
BP of 140/90
How is dyslipidemia a risk factor?
- If its genetic then it is not modifiable
- increase LDL cholesterol causes more foam cells to develop and more fatty streaks
How is tobacco use a risk factor?
- Nicotine causes catecholamine release leading to increase HR and vasoconstriction which increase stress on arteries
- Carbon monoxide is a chemical irritant that causes further injury to endothelium.
How is diabetes a risk factor?
Lipid metabolism is affected with diabetes which increases cholesterol, endothelial dysfunction that leads to plaque formation.
How is obesity a risk factor?
- Associated with HTN, diabetes, increase cholesterol will predispose stroke because often times with high BMI comes those things hence why it would be helpful to engage in weight loss.
How is Elevated stress a risk factor?
Increase in stress results in increase SNS stimulation which increases BP
How is substance abuse a risk factor?
- Cocaine and meth can cause anterior spasm or cerebral vasospasm and can cause constriction of blood vessels
- oxygen demand can increase
why is vasospasm more dangerous in younger people who do meth and cocaine?
Young people does not have collaterals so if they get vasospasm brain cannot get blood flow.
How is alcohol a risk factor?
- Affects the liver causing low clotting factors and vitamin k
- If person cannot clot then theres a risk for hemorragic stroke
- Alcohol also increase in BP and contributes to weight gain
What is arteriovenous malformations?
Congenital abnormalities, Arteriovenous malformations (AVMs) happen when a group of blood vessels in your body forms incorrectly. In these malformations, arteries and veins are unusually tangled and form direct connections, bypassing normal tissues.
- Sometimes they are asymptomatic
How is arteriovenous malformation a risk factor?
- Stress or blood thinners can rupture the abnormal blood vessel which can cause hemorrhagic stroke
what kind of medications are risk factors for stroke?
- anticoagulant
- antiplatelets
How can Medications be a risk factor?
Increase risk for bleeding = hemorrhagic stroke
How can atrial fibrillation be a risk factor?
- clots can form due to atrial fibrillation ( heart shaking) which can lodge in the cerebral arteries and cause embolic stroke
How can sedentary be a risk factor?
- Lack of mobility and being sedentary can cause hypercuagulation (clots) state which can go to the brain and cause stroke
- higher risk for obesity and weight gain which can cause increase in BP and increase risk for stroke
How can birth control pills/ Hormone replacement therapy/pregnancy be a risk factor?
Increase in estrogen and progesterone can increase clotting factors, increase activity of clotting factors, enhance platelet aggregations, and hypercuagulable state.
- Dose dependent
How can TIA (transient ischemic attack) be a risk factor?
- It is a warning sign before full blown stroke
- High risk for stroke
- “mini stroke”
what are “modifiable” risk factors?
those factors that can potentially be altered through lifestyle changes and medical treatments, thus reducing the risk for stroke.
examples of modifiable risk factors?
- Hypertension
- Heart disease; Arterial fibrillation
- Diabetes
- ETC.. Look at notes
What does “non-modifiable” risk factor means? What does it include?
- Risk factors that we cannot change
- Age, race & ethnicity, gender, family history, heredity, and low birth weight.