cardiovascular stroke
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Ischemia - inadequate blood flow
Stroke occurs when there is ischemia to a part of
the brain that results in death of brain cells
◦ BRAIN ATTACK
Functions are lost or impaired
◦ Such as movement, sensation, or emotions that were
controlled by the affected area of the brain
Severity varies according to the location & extent
of the brain involved
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3rd most common cause of death in the US &
Canada
Leading cause of serious, long-term disability
Approx. 25% of those who have an initial stroke
die within 1 year
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Age
◦ Doubles each decade after 55; can occur at any age
Gender
◦ More common in men; women more likely to die
Race
◦ Incidence almost 2x higher in Afr. Americans than whites
◦ Twice as likely to die
Heredity/family history Hispanics, Native Americans, and Asian Americans
have higher incidence of strokes than whites
Family hx, prior TIA or stroke also increase risk
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Hypertension Metabolic syndrome
Heart disease
Heavy alcoholconsumption
Poor diet
Drug abuse
Sleep apnea Obesity
Physical inactivity
Smoking “Hypertension is
most importantmodifiable risk
factor Still oftenundetected andinadequatelytreated”
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Blood is supplied to the brain by two major pairs of
arteries
◦ Internal carotid arteries
◦ Vertebral arteries
Carotid arteries branch to supply most of the
◦ Frontal, parietal, and temporal lobes
◦ Basal ganglia
◦ Part of the diencephalon
Thalamus
Hypothalamus
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Vertebral arteries join to form the basilar
artery, which supplies◦ Middle and lower temporal lobes
◦ Occipital lobes◦ Cerebellum
◦ Brainstem
◦ Part of the diencephalon
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Fig. 58-1
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Brain requires a continuous supply of blood to
provide the oxygen and glucose neurons need to
function
If blood flow to brain is totally interrupted
◦ Neurologic metabolism is altered in 30 seconds
◦ Metabolism stops in 2 minutes
◦
Cellular death occurs in 5 minutes
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Brain is normally well protected from changes inmean systemic arterial BP
◦ Cerebral autoregulation
Cerebral autoregulation involves
◦ Changes in diameter of cerebral blood vessels in
response to changes in pressure
Blood flow to the brain stays constant
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Factors affecting blood flow to brain◦ Systemic blood pressure
◦ Cardiac output
◦ Blood viscosity
Collateral circulation may develop
◦ Compensates for decreased cerebral blood flow
◦ An area can potentially receive blood from another blood
vessel if original blood supply is cut off
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Atherosclerosis - hardening and thickening of arteries & is a major cause of stroke
Can lead to thrombus formation and contribute toemboli
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Fig. 58-2
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In response to ischemia, a series of metabolicevents (ischemic cascade) occur
◦ Inadequate adenosine triphosphate (ATP) production
◦Loss of ion homeostasis
◦ Release of excitatory amino acids
◦ Free radical formation
◦ Cell death
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Around the core area of ischemia is a border zoneof ↓ blood flow
Ischemia is potentially reversible
If adequate blood flow can be restored early (<3
hours) & the ischemic cascade can be interrupted
◦ Less brain damage and less neurologic function lost
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Transient ischemic attack (TIA) is a temporaryfocal loss of neurologic function caused by
ischemia
Most TIAs resolve within 3 hours
TIAs may be due to microemboli that temporarily
block the blood flow
TIAs are a warning sign of progressivecerebrovascular disease
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Computed tomography (CT) of the brain w/ocontrast is the most important initial diagnostic
study
Cardiac monitoring & tests may reveal underlying
cardiac condition that is responsible for clot
formation
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Ischemic stroke◦ Inadequate blood flow to the brain from partial or
complete occlusion of an artery
80% of all strokes are ischemic
◦ Thrombotic stroke
Most common; 2/3 associated with hypertension & diabetes;often preceded by TIA
Thrombotic – clot forms due to narrowing of artery from fatty
deposits
◦
Embolic stroke 2nd most common; clot usually forms inside heart; sudden
onset of severe symptoms; may be conscious with c/o
severe HA; recurrence common
Clot forms somewhere else and gets lodged in cerebral
artery
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Fig. 58-3
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Hemorrhagic stroke◦ Result from bleeding into the brain tissue itself or into the
subarachnoid space or ventricles◦ 15% of all strokes
◦ Intracerebral hemorrhage Ruptured vessel in brain caused by hypertension; associated
with activity; sudden onset of SX
◦ Subarachnoid hemorrhage Bleeding into cerebrospinal fluid –filled space between the
arachnoid and pia mater Common cause is rupture of a cerebral aneurysmSubarachnoid hemorrhage of aneurysm - “Worst headache of one’s
life”
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Intracerebral hemorrhage◦ Manifestations
Neurologic deficits
Headache Nausea and/or vomiting
Decreased levels of consciousness
Hypertension
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Fig. 58-5
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Most obvious effect of stroke
Include impairment of
◦ Mobility
◦ Respiratory function
◦ Swallowing and speech
◦ Gag reflex
◦ Self-care abilities
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An initial period of flaccidity◦ May last from days to several weeks
◦ Related to nerve damage
Spasticity of the muscles follows the flaccid stage
◦ Related to interruptions of upper motor neuron influence
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Patient may experience aphasia when a strokedamages dominant hemisphere of the brain
◦ Aphasia is a total loss of comprehension and use of
language
◦ Dysphasia refers to difficulty related to the
comprehension or use of language and is due to
partial disruption or loss
◦ Dysphasia can be classified as nonfluent or fluent
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Many patients experience dysarthria◦ Disturbance in the muscular control of speech
Impairments may involve◦ Pronunciation
◦ Articulation
◦ Phonation
Dysarthria does not affect the meaning of
communications or the comprehension of language
It does affect the mechanics of speech
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Patients who suffer a stroke may have difficultycontrolling their emotions
Emotional responses may be exaggerated or
unpredictable
Depression and feelings associated with changes
in body image and loss of function can make this
worse
Patients may also be frustrated by mobility and
communication problems
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Both memory and judgment may be impaired as a
result of stroke
A left-brain stroke is more likely to result inmemory problems related to language
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Stroke on the right side of the brain is more likely
to cause problems in spatial-perceptual orientation
However, this may occur with
left-brain stroke
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Spatial-perceptual problems may be divided into 4
categories1. Incorrect perception of self and illness
2. Erroneous perception of self in space3. Inability to recognize an object by sight, touch, or
hearing
4. Inability to carry out learned sequential movements on
command
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Most problems with urinary and bowel elimination
occur initially and are temporary
When a stroke affects one hemisphere of thebrain, the prognosis for normal bladder function is
excellent
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CT is the primary diagnostic test used after a
stroke◦ Should be obtained within 25 min; read within 45 min
of arrival at ER◦ Will indicate size & location of lesion
◦ Differentiate between ischemic and hemorrhagic
stroke
When sx of stroke occur, studies are done to◦ Confirm that it is a stroke & identify the likely cause
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Other studies to diagnose a stroke, includingextent of involvement◦ CTA
◦ MRI,MRA
◦ SPECT
◦ PET
◦ MRS
◦ Others to measure cerebral flow
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Cardiac assessment◦ EKG
◦ Chest X-Ray
◦ Cardiac enzymes
◦ Echocardiogram
◦ Holter monitor
Additional studies- CBC, PLT,PT/PTT,
electrolytes, glucose; BUN/CREAT, LFT, lipid
profile
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Patients with known risk factors require close
management◦ Diabetes mellitus
◦ Hypertension
◦ Obesity
◦ High serum lipids
◦ Cardiac dysfunction
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Smoking should be discontinued
Limited alcohol intake
Healthy diet
Weight control
Regular exercise
Routine health examinations
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Antiplatelet drugs are usually the chosen
treatment to prevent further stroke in patients who
have had a TIA
Aspirin is the most frequently used antiplatelet
agent
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Surgical interventions for the patient with TIAs
from carotid disease include◦ Carotid endarterectomy
◦
Transluminal angioplasty◦ Stenting
◦ Extracranial-intracranial bypass
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Fig. 58-6
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Fig. 58-7
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Goals for collaborative care during the acute
phase are
◦ Preserving life
◦ Preventing further brain damage◦ Reducing disability
Treatment differs according to type of stroke and
as patient changes
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Begins with managing the ABCs
◦ Airway
◦ Breathing
◦ Circulation
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Assessment findings◦ Altered level of consciousness
◦ Weakness, numbness, or paralysis
◦
Speech or visual disturbances◦ Severe headache
◦ ↑ or ↓ heart rate
◦ Respiratory distress
◦ Unequal pupils
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Assessment findings◦ Hypertension
◦ Facial drooping on affected side
◦ Difficulty swallowing
◦ Seizures
◦ Bladder or bowel incontinence
◦ Nausea and vomiting
◦ Vertigo
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Interventions: Initial◦ Ensure patient airway
◦ Call stroke code or stroke team
◦ Remove dentures
◦ Perform pulse oximetry◦ Maintain adequate oxygenation
◦ IV access with normal saline
◦ Maintain BP according to guidelines
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Interventions: Initial
◦ Remove clothing
◦ Obtain CT scan immediately
◦ Perform baseline laboratory tests
◦ Position head midline
◦ Elevate head of bed 30 degrees if no symptoms of
shock or injury
◦ Institute seizure precautions
◦ Anticipate thrombolytic therapy for ischemic stroke
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Hypertension is common immediately after stroke◦ Drugs to lower BP are used only if BP is markedly
increased
Fluid and electrolyte balance must be controlledcarefully◦ Adequate hydration promotes perfusion and
decreases further brain injury
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Interventions: Ongoing◦ Monitor vital signs and neurologic status
Level of consciousness
Monitor and sensory function
Pupil size and reactivity
O2 saturation
Cardiac rhythm
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Recombinant tissue plasminogen activator (tPA)
◦ Used to reestablish blood flow through a blocked artery
to prevent cell death to patients with acute onset of
ischemic stroke symptoms
◦ Must be administered within 3 hours of onset of clinical
signs of ischemic stroke
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Aspirin is used within 48 hours of stroke
Platelet inhibitors and anticoagulants may be usedin thrombus and embolus stroke patients after
stabilization
◦ Contraindicated for patients with hemorrhagic stroke
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Approximately 5% to 7% of patients who
experience a stroke will have seizures, usually
within 24 hours
◦ Phenytoin is given if seizures occur
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Surgical interventions for stroke
◦ Immediate evacuation of
Aneurysm-induced hematomas
Cerebellar hematomas (>3 cm)
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Fig. 58-8
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Fig. 58-10
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After stabilized for 12-24 hours, care shifts from
preserving life to lessening disability & attaining
optimal functioning
May be transferred to rehab unit, outpatient
therapy, or home care –based rehabilitation
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Ineffective tissue perfusion
Ineffective airway clearance
Impaired physical mobility
Impaired verbal communication
Unilateral neglect
Impaired urinary elimination
Impaired swallowing Situational low self-esteem
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Goals are that the patient will◦ Maintain stable or improved level of consciousness
◦ Attain maximum physical functioning
◦
Maximize self-care abilities and skills◦ Maintain stable body functions
◦ Maximize communication abilities
◦ Avoid complications of stroke
◦
Maintain effective personal and family coping