cardiovascular stroke

7/28/2019 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

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

◦ Doubles each decade after 55; can occur at any age

Gender

◦ More common in men; women more likely to die

◦ 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

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”

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

Vertebral arteries join to form the basilar

artery, which supplies◦ Middle and lower temporal lobes

◦ Occipital lobes◦ Cerebellum

◦ Brainstem

◦ Part of the diencephalon

Fig. 58-1

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

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

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

Atherosclerosis - hardening and thickening of arteries & is a major cause of stroke

Can lead to thrombus formation and contribute toemboli

Fig. 58-2

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

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

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

Computed tomography (CT) of the brain w/ocontrast is the most important initial diagnostic

Cardiac monitoring & tests may reveal underlying

cardiac condition that is responsible for clot

formation

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

Fig. 58-3

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”

Intracerebral hemorrhage◦ Manifestations

Neurologic deficits

Headache Nausea and/or vomiting

Decreased levels of consciousness

Hypertension

Fig. 58-5

Most obvious effect of stroke

Include impairment of

◦ Mobility

◦ Respiratory function

◦ Swallowing and speech

◦ Gag reflex

◦ Self-care abilities

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

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

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

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

Patients may also be frustrated by mobility and

communication problems

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

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

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

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

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

Other studies to diagnose a stroke, includingextent of involvement◦ CTA

◦ MRI,MRA

◦ SPECT

◦ PET

◦ MRS

◦ Others to measure cerebral flow

Cardiac assessment◦ EKG

◦ Chest X-Ray

◦ Cardiac enzymes

◦ Echocardiogram

◦ Holter monitor

Additional studies- CBC, PLT,PT/PTT,

electrolytes, glucose; BUN/CREAT, LFT, lipid

profile

Patients with known risk factors require close

management◦ Diabetes mellitus

◦ Hypertension

◦ Obesity

◦ High serum lipids

◦ Cardiac dysfunction

Smoking should be discontinued

Limited alcohol intake

Healthy diet

Weight control

Regular exercise

Routine health examinations

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

Surgical interventions for the patient with TIAs

from carotid disease include◦ Carotid endarterectomy

Transluminal angioplasty◦ Stenting

◦ Extracranial-intracranial bypass

Fig. 58-6

Fig. 58-7

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

Begins with managing the ABCs

◦ Airway

◦ Breathing

◦ Circulation

Assessment findings◦ Altered level of consciousness

◦ Weakness, numbness, or paralysis

Speech or visual disturbances◦ Severe headache

◦ ↑ or ↓ heart rate

◦ Respiratory distress

◦ Unequal pupils

Assessment findings◦ Hypertension

◦ Facial drooping on affected side

◦ Difficulty swallowing

◦ Seizures

◦ Bladder or bowel incontinence

◦ Nausea and vomiting

◦ Vertigo

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

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

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

Interventions: Ongoing◦ Monitor vital signs and neurologic status

Level of consciousness

Monitor and sensory function

Pupil size and reactivity

O2 saturation

Cardiac rhythm

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

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

Approximately 5% to 7% of patients who

experience a stroke will have seizures, usually

within 24 hours

◦ Phenytoin is given if seizures occur

Surgical interventions for stroke

◦ Immediate evacuation of

Aneurysm-induced hematomas

Cerebellar hematomas (>3 cm)

Fig. 58-8

Fig. 58-10

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

Ineffective tissue perfusion

Ineffective airway clearance

Impaired physical mobility

Impaired verbal communication

Unilateral neglect

Impaired urinary elimination

Impaired swallowing Situational low self-esteem

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

cardiovascular stroke

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