6. Stroke Flashcards by Alexis Elliott

What is the FAST acronym?

F: face drooping
A: arm weakness
S: slurred speech
T: time - call 911 immediately

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What is the most significant risk factor for stroke?

HTN

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Uncontrolled HTN poses a __x greater risk of stroke than those without HTN.

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Why does HTN increase the risk for stroke?

↑ atherosclerosis

- weakens blood vessels in brain

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What are the risk factors for stroke?

HTN
heart disease
DM
↑ cholesterol
smoking
cocaine

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What 2 heart conditions especially increase risk of stroke?

atrial fibrillation

- myocardial infarction

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Diabetics have __x the risk of stroke.

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Why does ↑ cholesterol increase chance of stroke?

plaques can block blood vessels and contribute to the formation of blood clots

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Smoking _____ the risk of ischemic stroke.

doubles

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Why does cocaine use increase the risk of stroke?

causes cerebrovascular constriction and arrhythmias

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What are the types of stroke?

ischemic
hemorrhagic
transiet ischemic attack

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Define ischemic stroke

Ischemic stroke occurs when an artery supplying the brain becomes obstructed.

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What is the most common cause of ischemic stroke?

thrombi

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What type of stroke is most common?

Ischemic (85%)

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Ischemic stroke ultimately causes brain ________.

infarction

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What are the 2 ways an ischemic stroke may occur?

thrombotic stroke

- embolic stroke

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What is a thrombotic stroke?

Thrombus forms on atherosclerotic plaque and blocks blood flow in an artery suppling part of the brain.

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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.

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What is a hemorrhagic stroke?

artery in the brain ruptures

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Why does a hemorrhagic stroke cause ischemia?

disrupts blood supply downstream of hemorrhage

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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

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In a healthy functioning brain, neurons never come in contact with whole blood. (T/F)

True

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How do neurons receive oxygen and nutrients?

blood-brain barrier

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In what ways can a hemorrhagic stroke occur?

bleeding aneurysm

- plaque-induced rupture

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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?

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