Cerebral Infarction Flashcards
What is a stroke?
Rapid loss of brain function due to a disturbance in the blood supply to the brain
What are the two types of stroke?
Ischemic - blockage caused by a thrombus and embolus
Haemorrhagic
Difference between thrombus and embolus
thrombus is in a vein due to small moving blood
embolus can be anything in any vessel that blocks blood flow (thromboembolism is a thrombus that has travelled)
Which arteries to the brain can be effected?
internal and external carotid
vertebral
Why is atrial fibrillation associated with stroke?
Dilated atria means blood is slow moving and allows clots to form
Define ischaemia
Reduced blood/oxygen supply to tissue
Define necrosis
Death of cells
What will happen to intracranial pressure during stroke and what is the danger of this?
Pressure will increase because of brain swelling which can damage nerve cells further
What % of strokes are ischaemic?
80%
In which patients are embolic strokes most common?
AF
Heart attack
After heart surgery
Which type of stroke is more dangerous and why?
Haemorrhagic
Can only be prevented by controlling high blood pressure and only helped by surgery
Risk factors for stroke
Age Hypertension Previous stroke/TIA Diabetes High cholesterol Smoking AF
What is digoxin used for?
AF
What is a TIA?
The result of temporary disruption of the circulation to part of the brain due to embolism or thrombosis to brain arteries.
recovery within 24 hours
Symptoms
Weakness of arm or leg on one side of body
Slurred speech (dysarthria)
Drooping of corner of mouth
Dysphagia
Inability to find the right words to speak (expressive dysphasia)
Inability to understand others (expressive dysphasia)
What is expressive dysphasia?
Unable to understand speech/ find the right words to speak
Signs
FAST
Evidence of AF (irregular pulse)
Hypertension
Bruit (noise of turbulent blood flow hear over carotid artery in neck)
Abnormal test results
Brain CT or MRI showing ischaemia, swelling, infaction
Ultrasound of carotid artery showing narrowing due to atherosclerosis
Echocardiagram showing blood clot
ECG showing evidence of AF (irregular, absent P waves)
How does digoxin work?
Reduces conductivity of AV node to control heart rate, and increase force of contraction
Inhibits Na+/K+ ATPase which increases intracellular sodium which is exchanged for calcium = stronger contraction
How could wafarin help prevent stroke?
Prevent left atrial thrombus
What factors does warfarin stop and how?
10
9
7
2
interferes with vitamin k metabolism
What type of drug is lisinopril?
ACE inhibitor
How do ACE inhibitors work?
Block angiotensin converting enzyme (ACE) which turns angiotensin I into angiotensin II
angiotensin II acts on blood vessels to cause vasconstriction
so ACE inhibitors (e.g. lisinopril) lower blood pressure
What are some types of antihypertensives?
angiotensin converting enzyme inhibitors (ACEi) angiotensin II receptor blockers Beta blockers Calcium channel blockers Thiazides
How do beta blockers reduce blood pressure?
Block adrenaline to lower heart rate and lower bp
How do calcium channel blockers reduce blood pressure?
revent calcium from entering cells of the heart and blood vessel walls to slow contractions, resulting in lower blood pressure
relax and widen blood vessels by affecting the muscle cells in the arterial walls
How do Thiazides reduce bp?
increasing the amount of salt and water that is excreted through urine
How can stroke be prevented?
Anticoagulants (warfarin) for AF
Antiplatelets (aspirin) for carotid atherosclerosis
Antihypertensives
