6. Stroke Flashcards
What is the FAST acronym?
F: face drooping
A: arm weakness
S: slurred speech
T: time - call 911 immediately
What is the most significant risk factor for stroke?
HTN
Uncontrolled HTN poses a __x greater risk of stroke than those without HTN.
5
Why does HTN increase the risk for stroke?
- ↑ atherosclerosis
- weakens blood vessels in brain
What are the risk factors for stroke?
- HTN
- heart disease
- DM
- ↑ cholesterol
- smoking
- cocaine
What 2 heart conditions especially increase risk of stroke?
- atrial fibrillation
- myocardial infarction
Diabetics have __x the risk of stroke.
3
Why does ↑ cholesterol increase chance of stroke?
plaques can block blood vessels and contribute to the formation of blood clots
Smoking _____ the risk of ischemic stroke.
doubles
Why does cocaine use increase the risk of stroke?
causes cerebrovascular constriction and arrhythmias
What are the types of stroke?
- ischemic
- hemorrhagic
- transiet ischemic attack
Define ischemic stroke
Ischemic stroke occurs when an artery supplying the brain becomes obstructed.
What is the most common cause of ischemic stroke?
thrombi
What type of stroke is most common?
Ischemic (85%)
Ischemic stroke ultimately causes brain ________.
infarction
What are the 2 ways an ischemic stroke may occur?
- thrombotic stroke
- embolic stroke
What is a thrombotic stroke?
Thrombus forms on atherosclerotic plaque and blocks blood flow in an artery suppling part of the brain.
What is an embolic stroke?
A clot forms in another part of the body (often heart) and migrates until it lodges in a brain artery.
What is a hemorrhagic stroke?
artery in the brain ruptures
Why does a hemorrhagic stroke cause ischemia?
disrupts blood supply downstream of hemorrhage
Aside from ischemia, what damage can a hemorrhagic stroke cause?
- blood disrupts the chemical balance needed by neurons to function
- vascular blood loss may increase pressure on surrounding brain tissue
In a healthy functioning brain, neurons never come in contact with whole blood. (T/F)
True
How do neurons receive oxygen and nutrients?
blood-brain barrier
In what ways can a hemorrhagic stroke occur?
- bleeding aneurysm
- plaque-induced rupture
What is an aneurysm?
a weakened segment of an artery that can stretch or balloon out under high pressure
What often causes aneurysms?
HTN
What is a plaque-induced rupture?
Artery walls that have lost elasticity and become brittle and thin can rupture.
What is the common term for a TIA?
mini-stroke
What causes TIA?
emboli that are then spontaneously dissolved by the fibrinolytic system, allowing re-established blood flow
What is the average duration of a TIA?
a few minutes
How are strokes diagnosed?
CT or MRI
What is the most widely used imaging method for diagnosing stroke?
CT
What is the unique diagnostic benefit of CT?
rule out hemorrhage
MRI is sensitive to detection of _______.
ischemia
What are the disadvantages of using MRI over CT?
- takes longer to perform
- less widely available
What is primary stroke prevention?
- reducing risk factors
- ASA for those with evident atherosclerosis
What is secondary stroke prevention after TIA?
Inhibiting platelet aggregation
- ASA
- Aggrenox
ADP receptor antagonists are ineffective in preventing stroke. (T/F)
False: effective but $$$
What ADP receptor antagonists are useful in preventing stroke?
- clopidogrel
- prasugrel
- ticagrelor
What is the treatment for acute ischemic stroke?
IV recombinant tissue-type plasminogen activator: alteplase (Activase)
What is the only FDA approved thrombolytic agent for ischemic stroke?
alteplase
When can alteplase be used to treat acute ischemic stroke?
within 3 hours of symptom onset
What is the dose of alteplase when treating ischemic stroke?
0.9 mg/kg with 10% of dose given as bolus followed by 60 minute infusion
What are contraindications of alteplase?
- hemorrhagic stroke or head injury within 3 months
- major surgery within 2 weeks
- seizures at stroke onset
When are anticoagulants indicated in ischemic stroke?
worsening symptoms
What is the dose for heparin in ischemic stroke?
- loading dose 50 - 100 U/kg
- continuous IV infusion to maintain aPTT 1.5-2.5 x normal
In what patients would warfarin be used for stroke prophylaxis?
patients with a.fib or prosthetic heart valve
What is the most common cause of cardioembolic stroke?
atrial fibrillation
A recent study found aspirin to be superior to warfarin for stroke prevention in patients with atrial fibrillation and recent TIA. (T/F)
False: warfarin is superior to aspirin
What agents can be used for secondary stroke prevention?
- Aggrenox
- Aspirin
- ADP receptor antagonists
- Direct thrombin/Xa inhibitors
What is the dose of dabigatran for stroke prevention (non-valvular a.fib)?
150 mg BID
What is the dose frequency for rivaroxaban for stroke prevention (non-valvular a.fib)?
single daily dose
What is the dose frequency for apixaban for stroke prevention (non-valvular a.fib)?
BID
What are the treatments for ischemic stroke that are currently under investigation?
Desmoteplase: thrombolytic agent
Ancrod: heparin alternative
What is desmoteplase?
recombinant desmodus (vampire bat) salivary plasminogen activator
How does desmoteplase compare to alteplase?
- greater selectivity for fibrin bound plasminogen
- prolonged half-life
What is ancrod (Viprinex) derived from?
venom of Malayan pit vipers
What is the MOA of ancrod?
- degrades fibrinogen in circulation
- decreases blood viscosity
- induces the release of endogenous t-PA from the vessel wall
Why was ancrod development terminated?
increased risk of intracranial bleeding
What is the only pharmacological treatment of hemorrhagic stroke?
nimodipine (Nimotop)
What is nimodipine?
a CCB
What is the route of administration of nimodipine?
oral
Where does nimodipine have the greatest effect?
vascular smooth muscle of cerebral arteries as compared to peripheral arteries
What chemical feature of nimodipine allows it to have good activity in brain?
highly lipophilic
Why is nimodipine beneficial in strokes?
- ↑ blood flow in ischemic brain areas
- ↓ neurological deficits caused by cerebral vasospasm following subarachnoid hemorrhage
