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Cardiovascular System Disease > Stroke Lecture > Flashcards

Stroke Lecture Flashcards

1
Q

STROKE: Defined

A

Destruction of a portion of brain tissue as a result of circulatory failure in the distribution of a specific arterial vessel

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2
Q

Ischemic Stroke (84%) - Thrombotic (53%): Cause, Onset, Risk factors

A

Thrombotic (53%)

 Cause: Platelet Aggregation/Vessel Occlusion

 Onset: During Sleep when BP is lowest

 Risk Factors:
- Large Vessel Disease
- Atherosclerosis
- Dissection
- Arteritis
 Small Vessel Disease
- Chronic Hypertension
- Lacunar : small subcortical infarcts
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3
Q

Hemorrhagic Strokes (16%)

A

Bleeding around brain
SAH (Subarachnoid Hemorrhage) (6%)
 Ruptured Aneurysm

Bleeding inside brain (10%)
 ICH (Intracerebral Hemorrhage)
 Hypertension
 Cocaine
 Many other
 IVH (Intraventricular Hemorrhage)
 Usually an extension of ICH
 Rarely isolated
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4
Q

Stroke Symptoms

A 
 Sudden onset of weakness / numbness of face, arm, leg
 Sudden decrease in level of consciousness
 Facial droop
 Confusion
 Aphasia
 Dysarthria
 Visual field deficit (difficulty seeing with one or both eyes)
 Hemisensory deficits
 Ataxia
 Difficult walking
 Dizziness
 Severe headache and vertigo
 Nausea or vomiting
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5
Q

Acute Management of

Ischaemic Stroke

A 
Accurate diagnosis of stroke
Definition of stroke type
Acute general medical care
Re-perfusion
Neuroprotection
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6
Q

Pathology

A

Ischemia  energy deficit
Na+/K+ channel failure in the cell
Cause cytotoxic edema: shift of water into intracellular compartment
Leads to a narrowing of the extracellular matrix
Restricted diffusion of water within the cell
Increase signal which can be measured with DWI

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7
Q

Core and Penumbra

A

• In the absence of blood flow, available energy can maintain neuronal viability for 2-3 minutes
• In the brain, ischemia is incomplete, with collateral supply
• Cerebral ischemia = central irreversibly infarcted tissue core surrounded by peripheral region of stunned cells, the ‘penumbra’
• The penumbra is potentially salvageable with early
recannalization

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8
Q

Penumbra

A

 When a cerebral artery is occluded, a core of brain tissue dies rapidly (irreversible)
 Surrounding this infarct core is an area of brain that is hypoperfused but does not die quickly, because of collateral blood flow,
 This surrounding area is penumbra (salvageable)
 Its fate depend on the reperfusion of the ischemic brain
 Will also die unless early recanalization is present
 Thrombolysis via tPA, thrombus removal, etc.

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9
Q

Coagulation

A

Coagulation Factors
Fibrinogen
Fibrin

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10
Q

Fibrinolysis

A

Tissue Plasminogen Activator
Plasminogen
Plasmin
Fibrinolysis

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11
Q

Recombinant Tissue Plasminogen Activator (rt-PA)

A
  1. Structure. Naturally occurring plasminogen activator present in most normal and neoplastic cells, Mr = 68,000 daltons. Preferentially activates plasminogen bound to fibrin.
  2. Mechanism of action. Converts plasminogen to plasmin, which lyses fibrin clots.
  3. NIND study (1995); European Cooperative Acute Stroke Study (ECASS I, ECASS III); Alteplase Thrombolysis for Acute Noninterventional Therapy in Ischemic Stroke (ATLANTIS trial)
  4. Approved in US in 1996; Approval in Canada in 1999
  5. Indications. Alteplase is FDA approved for MI and acute ischemic stroke
  6. Method of administration. I.V. or I.A. injection
  7. Major side effects. Bleeding.
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12
Q

Thrombolysis

A

Alteplase (0.9mg/kg) - Within 4.5 hours of the stroke.

The efficacy of thrombolytic drugs depends on the age of the clot. Older clots have more fibrin cross-linking and are more compacted or in plain English older clots are more difficult to dissolve.

Beyond that time, the efficacy diminishes and higher doses are generally required to achieve desired lysis and the great the risk of unwanted complications.

10% of total dose bolus 2-3 mins
90% of total dose infuse over 60 mins

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13
Q

Risks: Hemorrhagic Transformation

A

Occurs in ~ 3% patients with ischemic stroke ~ 4% patients who received tPA (within 36 hrs of infusion)

Cause:
 Ischemic brain and damaged blood vessels
 Injured blood vessels become “leaky”
 Restored blood flow results in hemorrhage

Occurrence influenced by:
Size and location of infarct; Degree collateral circulation;
Use of anticoagulants and interventions;
Increased thrombolytic dose; Treatment initiated > 3h;
Elevated blood pressure; NIHSS > 20;
Acute hypodensity or mass effect.

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14
Q

Hemorrhagic Transformation - symptoms

A

 Neurological worsening
 Increased BP
 Respiratory changes

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15
Q

Hemorrhagic Transformation - management

A

CT
Control BP
Avoid use of anticoagulants
Possible surgery

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16
Q

Administration of rtPA (Protocol Guidelines)

Inclusion criteria

A

Age 18 years or older
Signs of a measurable neurologic deficit from an ischemic stroke on examination
Time of onset < 4.5 hours

17
Q

Neuroprotection

A

• Neuroprotective therapies aim to block the molecular cascade of injury following ischaemic stroke.
– to minimize size of injury
– to extend therapeutic window

18
Q

Carotid Endarterectomy

A

If TIA due to ≥ 50% stenosis in extracranial internalcarotid artery consider CEA
Greatest benefit if surgery within 2 weeks
Surgical procedures may have serious risks and
may not favorably alter the outcome of the patient.

19
Q

Risk Factors - MODIFIABLE

A
  • Hypertension
  • Diabetes
  • High cholesterol
  • Cigarette smoking
  • Atrial Fibrillation
  • Cardiac disease
  • Hypercoagulative states
  • Obesity
  • Excessive Alcohol Intake
  • Physical Activity
  • Stress
  • Hormone replacement therapy
20
Q

Risk Factors - NONMODIFIABLE

A
  • Age
  • Gender
  • Race
  • Prior stroke/TIA
  • Heredity
21
Q

Initiate Medications: Antithrombotic Therapy

A

Aspirin (50-325 mg/day) is first line treatment
If aspirin naïve- load with 160mg then 81 mg OD
May administer aspirin only if CT not available
and symptoms resolved
If symptoms not resolved must have CT to exclude hemorrhage

22
Q

Stroke Prevention Guidelines

A
  1. Know your blood pressure.
  2. Find out if you have atrial fibrillation (AF)
  3. If you smoke, stop.
  4. If you drink alcohol, do so in moderation
  5. Know your cholesterol number
  6. If you are diabetic, follow your doctor’s advice;
  7. Exercise
  8. Low sodium and low fat diet
  9. Any stroke symptoms, call 999
23
Q

Continuum of Stroke Care

A
  • Prevention of stroke, Public awareness andpatient education
  • Hyperacute stroke management
  • Acute inpatient stroke care
  • Stroke rehabilitation andcommunity reintegration
24
Q

Ischemic Stroke (84%) - Embolic (31%): Cause, Onset, Risk factors

A 
 Cause: Fragments formed outside the brain break off
and travel to a vessel in the brain
 Onset: Abrupt, may occur during exercise
 Risk Factors
- Afib
- Endocarditis
- Valve Disease
- Patent Foramen Ovale (PFO)
25
Q

Define ischemic stoke

A

A clot block blood flow to an area of the brain

26
Q

Define hemorrhagic stoke

A

Bleeding occurs inside or around brain tissue

27
Q

Stroke diagnosis

A

Imaging –> CT or MRI

28
Q

Events in ischaemic stroke

A

Damage:

Excitotoxicity (minutes)

  • Glutamate
  • Ca2+
  • ORF

Inflammation and apoptosis (hours)

  • IL-1
  • COX-2
  • MMPs
  • Caspases

Protect:

Anti-Excitotoxicity (minutes)

  • GABA
  • Adenosine
  • kATP activation

Anti-Inflammation and Anti-apoptosis (hours)

  • IL-10
  • BCL proteins
  • EPO

Repair and regeneration (weeks)

  • Scar formation
  • Vasculogenesis
  • Neurogenesis
  • Increase of BM-derived cells

Cardiovascular System Disease (6 decks)

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