Risky BusinessIschemia Stroke who’s

at risk?Shaunta Ford-Pierce RN, BSN

April 4th , 2012

Alverno College

MSN 621

Tutorial Objectives

• Define Ischemic Stroke.

• Identify modifiable and non-modifiable risk factors, and explain how risk factors can cause stroke to occur.

• Discuss five main mechanisms of Ischemic Stroke.

• Describe the development of atherosclerosis and its relation to ischemic stroke.

• Explore teaching strategies and role in prevention of stroke.

Case study

• Mr. T is a 52 year-old, African American teacher who was brought to the school nurse’s office by another staff member. The staff member states that Mr. T was complaining of a headache and dizziness. After sitting down at his desk she states “it became hard to understand him and he just didn’t look right.” When the school nurse assessed Mr. T’s awareness he appeared confused and was unable to identify his birthdate and current location. Mr. T becomes weak and begins to slur his speech.

What is Ischemic Stroke?

According to the American Stroke Association, Ischemic stroke accounts for about 87% of all stroke cases. (American Stroke Association, 2012)

It occurs when there is an “interruption of blood flow in a cerebral vessel” causing damage to parts of the brain tissue and possibly leaving a “neurological deficit”. (Porth & Matfin, 2009)

Test your knowledgeMr. T appears to be having a stroke. What would most likely cause an interruption in blood flow in Ischemic Stroke?

Head Injury

Nice try! However a head injury that leads to a stroke

would most likely cause bleeding which would be a

hemorrhagic stroke

Migraine

Nice try! Although migraines have been linked to stroke it

is far less common than other causes of blood flow

obstruction.

Thrombi

Correct! “Ischemic strokes are caused by

cerebrovascular obstruction by thrombosis or emboli.”

(Porth & Matfin, 2009)

Causes of Ischemic Stroke

Blood Vessel

Blockage

Embolism: The traveling of a

clot from another part of the body to the

brain.

Stenosis: Narrowing of

artery or arteries

leading to the brain. Thrombosis:

Formation of a clot inside of

the blood vessel.

Ischemic stroke occurs due to blockage of a bloodvessel. There are three conditions that contribute to vessel blockage.

(Porth & Matfin, 2009)

Etiology of Stroke

There are five main mechanisms of ischemic stroke.

1. Large artery disease

2. Small vessel or penetrating artery disease

3. Cardiogenic embolism

4. Cryptogenic stroke

5. Other unusual causes such as migraine or vessel dissection.

(Porth & Matfin, 2009)

EtiologyLarge vessel Stroke

• The Large vessels that are usually involved in ischemic stroke found in the cerebral circulation are the arterial bifurcations. (Porth & Matfin, 2009)

• Common sites of origin include, “internal carotid, vertebral arteries and junctions of the basilar and vertebral arteries.” (Porth & Matfin, 2009)

Image taken from Wikepedia with permission under Creative Commons Attribution/Share-Alike License 3.0

Small Vessel Stroke (Lacunar Infarct)

• Small vessel stroke as known as Lacunar infarcts occur in the deeper, noncortical part of the brain or brain stem (Porth & Matfin, 2009).

• Unlike Large Vessel Thrombotic stroke two common causes of Lacunar infarct are microatheroma and lipohylinosis (Porth & Matfin,2009). Lipohylinosis is a small vessel disease “characterized by thickening on he arterial wall” (Wikipedia, 2011). Microatheroma is a build up of plaque on the innermost layer of the wall of an arterty (Miffin, 2007) .

• “They result from occlusion of smaller penetrating branches of large arteries” (Porth & Matfin, 2009).

• Manifestations of a Lacunar infarct include “ pure motor hemiplegia, pure sensory hemiplegia and dysarthria”(Porth & Matfin, 2009). Because Lacunar infarcts occur in the noncortical part of the brain these manifestations are unique to Lacunar infarct.

Cardiogenic Embolism Stroke

• This occurs when a clot or atherosclerotic plaque breaks off a vessel and travels from its origin to the brain, lodging at bifurcations. “Although most cerebral emboli originate from a thrombus in the left heart, they also may originate in an atherosclerotic plaque in the carotid arteries”(Porth &Matfin, 2009)

• Conditions that can cause cardiogenic embolism include: rheumatic heart disease, atrial fibrillation, recent heart attack, and bacterial endocarditis. (Porth &Matifin, 2009)

• Rheumatic heart disease and bacterial endocarditis can result in valvular disease such as mitral valve stenosis or mitral valve regurgitation. Valvular disease can disrupt the normal flow of blood throughout the heart causing changes in both the atrium and ventricle (Porth & Matfin, 2009). This leads to alterations in the hemodynamic functions which can cause pooling of blood in the chambers. When blood is stagnant in the heart it increases risk of clot formation which can lead to embolic stroke (Mayo Clinic, 2011).

Cardiogenic Embolism Stroke

• “In atrial fibrillation the upper chambers of the heart contract in a very fast and irregular way. As a result, some blood pools in the heart. The pooling increases the risk of blood clots forming in the heart chambers”( National Heart Lung and Blood Institute Explore Stroke, 2011 ). Similar to rheumatic heart disease a blood clot could break off and travel to the brain putting a person with this disorder at greater risk for stroke.

• Recent heart attack indicates a predisposition to clotting or atherosclerosis, of which is a causative factor for heart attack. Therefore the client is at a higher risk for recurrence of embolism of blood clot or plaque traveling to the brain causing stroke.

• “Embolic stroke usually has a sudden onset with immediate maximum deficit” (Porth & Matfin, 2009).

Cryptogenic stroke

• Cryptogenic stroke is when the etiology of stroke cannot be identified. “The classic risk factors for stroke are usually absent and yet cerebral angiography and transesophageal echocardiography do not reveal large-artery occlusive disease or an unequivocal cardioembolic source.” (Catalina et al., 2005)

Test your knowledge!

Name two main mechanisms of

ischemic stroke?

Hemorrhage

Sorry that is not correct. Hemorrhage would most likely

result in Hemorrhagic Stroke which is caused by a “weakened vessel that ruptures and bleeds into the

surrounding brain.” (American Stroke Association, 2012)

Large artery Atherosclerotic

disease

Yes that’s one! Atherosclerosis of the blood

vessels causing ischemic stroke is most commonly

found in the large vessels i.e.: arterial bifurcations. (Albers,

Amarencon, Easton, Sacco, & Teal, 2008)

Cardiogenic Embolism

Yes That’s right! Remember certain cardiac conditions can

predispose a patient to irregular clot formation likely to produce embolic stroke.

(Porth & Matfin, 2009)

Test your knowledge

What health conditions are likely to cause cardiogenic embolism leading to an ischemic stroke?

Atrial fibrillation

Yes! “The risk of arterial embolization, particularly

stroke, is significantly increased in persons with atrial fibrillation” (Porth &

Matfin, 2009).

Thrombocytopenia

Sorry that is not correct, thrombocytopenia or low

platelets can put patients at risk for bleeding therefore it is

far more likely that thrombocytopenia could put a patient at risk for hemorrhagic

stroke.

Rheumatic Heart disease

Good job! Mitral valve stenosis is commonly seen in

RHD, which can lead to formation of embolism due to

impaired filling of left ventricle and atrial distention.

As well as irregular heart rhythm (Porth & Matfin,

2009).

Case Study

After calling Emergency Medical Services (EMS) to the scene the School Nurse contacts Mr. T’s wife to get a history of any medication or medical conditions that Mr. T may have so that she can inform the EMS team when they arrived. She is told that Mr. T only takes an antihypertensive medication daily with his multivitamin. Mr. T is also a smoker and has a history of a “mini stroke” eight months prior to today.

Risk factors

• What factors from Mr. T’s history increase his risk for ischemic stroke?

History of Stroke

Yes, “The risk of stroke for someone who has already had

one is many times that of a person who has not”

(American Stroke Association, 2012).

Smoker

Yes, The nicotine and carbon monoxide in cigarette smoke damage the cardiovascular

system such as the endothelium of the blood vessels causing an initial injury to the blood vessel.

(American Stroke Association, 2012)

Antihypertensive Medication

Yes, this is an indication that Mr. T has hypertension which is a risk factor for stroke because of the damage it causes to the blood vessels leading to plaque or

atherosclerosis thus increasing risk for stroke. (Porth & Matfin, 2009)

Antihypertensive

Medication

Yes, this is an indication that Mr. T has hypertension which

is a risk factor for stroke because of the damage it

causes to the blood vessels leading to plaque or atherosclerosis thus

increasing risk for stroke. (Porth & Matfin, 2009)

Risk factors

• “A risk factor is a condition or behavior that occurs more frequently in those who have, or are at greater risk of getting, a disease than in those who don’t.” (National Institute of Neurological Disorders and Stroke, 2012).

• Risk factors for stroke can be divided into two groups modifiable and non-modifiable risk (National Institute of Neurological Disorders and Stroke, 2012).

• Modifiable risk factors are things that can be changed or treated (National Institute of Neurological Disorders and Stroke, 2012).

• Non-modifiable risk factors are things that cannot be changed (National Institute of Neurological Disorders and Stroke, 2012).

Modifiable vs. Non-Modifiable

Modifiable Risk factors

• High blood pressure

• Cigarette smoking

• Heart disease

• Diabetes

• Cholesterol imbalance

• Sickle Cell Disease

Non-Modifiable Risk factors

• Age

• Race

• Gender

• Family History

(National Institute of Neurological Disorders and Stroke, 2012)

Modifiable Risk Factors

• Sickle cell disease is characterized by sickled blood cells which can cause narrowing of arteries and disrupt blood flow (Porth &Matfin, 2009).

• Heart conditions such as “valve defects, irregular heart beat and enlargement of one of the heart’s chambers can result in blood clots” that can travel to the brain. (Porth & Matfin, 2009).

Modifiable Risk factors continued

• Atherosclerosis of large and small arteries that supply the brain is the most common cause of ischemic stroke. (Albers, Amarencon, Easton, Sacco, & Teal, 2008)

• High blood pressure, smoking, diabetes and cholesterol imbalance (specifically high LDL levels) can all contribute to the development of atherosclerosis. (Porth & Matfin, 2009)

Development of Atherosclerosis

• Endothelial Cell injury ; Agents such as smoking, high LDL, and mechanical stress (hypertension) can cause endothelial injury with adhesions of monocytes and platelets. (Porth & Matfin, 2009 )

• Migration of inflammatory cells; inflammatory cells such as monocytes initiate atherosclerotic lesions (Porth & Matfin, 2009 ).

• Smooth muscle cell proliferation and lipid deposition (Porth & Matfin, 2009 ).

• Development of plaque with lipid core (Porth & Matfin, 2009 ).

• Development of atherosclerosis can cause narrowing of the blood vessel which could lead to ischemia. Also plaque hemorrhage or rupture (of plaque) can migrate and lodge in other blood vessels in the brain causing stroke (Porth & Matfin, 2009 ).

(Porth & Matfin, 2009)

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Non-Modifiable Risk Factors

• Individual risk doubles for each decade between 55-85 years of age.

• “The incidence of stroke increases with age, with men’s stroke incidence rates being greater than women’s at younger ages, but not at older ages” (Porth &Matfin, 2009).

• African-Americans are more at risk than any other ethnicity or race.

• Family history could be an inherited disposition or “ a common lifestyle among family members”(National Institute of Neurological Disorders and Stroke, 2012).

(Porth & Matfin, 2009)

Test your Knowledge

True or False: Hypertension, high cholesterol, and cigarette can aid in the development of atherosclerotic vessels.

True

Correct! These condition can cause initial injury to

endothelial walls, initiating several inflammatory

responses ultimately causing plaque formation in blood vessels (Porth & Matfin,

2009).

False

Sorry that is not correct

Test your knowledge!

Identify which risk factors are modifiable and non-modifiable.

65 year-old Male

Non-modifiable

High Fat diet

ModifiableSickle Cell Anemia

Modifiable, although sickle cell anemia is an inherited

disease it can be treated and managed to lower the risk of

stroke.

High Fat diet

Modifiable, because diet modification can lower

cholesterol and improve blood pressure which can decrease risk for stroke.

65 year-old Male

Non-modifiable, because gender and age cannot be

changed.

Raising awareness

• Nurses play a crucial role in the prevention of stroke and raising awareness of risk factors for stroke.

• Nurse can influence client lifestyle choices by assessing their belief system which is “essential to the adoption and maintenance of self care before and after stroke.” (Mayo Clinic, 2001-2012)

• Empower patients to know their risk for stroke as well as knowing signs and symptoms of stroke to improve the likelihood of seeking medical attention promptly.

(Mayo Clinic, 2001-2012)

Summary

• Ischemic stroke is an interruption in blood flow to cerebral vessel or vessels subsequently causing damage to brain tissue and neurological deficit (Porth & Matfin, 2009).

• Modifiable risk factors for stroke include smoking, heart disease, high blood pressure, cholesterol imbalance and sickle cell disease (National Institute of Neurological Disorders and Stroke, 2012).

• Three common mechanisms of ischemic stroke are large artery disease, small vessel disease and cardiogenic embolism(Porth & Matfin, 2009).

• Atherosclerosis of a large and small vessels is a common precursor to ischemic stroke (Porth & Matfin, 2009).

• Health education and raising awareness about stroke risk is a key component in the prevention of ischemic stroke (Mayo Clinic, 2001-2012).

Literature Cited

• Albers, G. W., Amarencon, P., Easton, D. J., Sacco, R. L., & Teal, P. (2008). Antithrombotic and Thrombolytic Therapy for Ischemic Stroke : American College of of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest Journal , 630S-669S.

• American Stroke Association. (2012). Ischemic Strokes. Retrieved March 15th, 2012, from www.strokeassociation.org: http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/IschemicClots/Ischemic-Strokes-Clots_UCM_310939_Article.jsp#.T3j1dvBSSSp

• Catalina C. Ionita, MD; 1 Andrew R. Xavier, MD; 2 Jawad F. Kirmani, MD; Subasini Dash, MD; 3 Afshin A. Divani, PhD; 2 Adnan I. Qureshi, MD 2. (2005, April 5th). What Proportion of Stroke Is Not Explained by Classic Risk Factors? Retrieved April 3rd, 2012, from Medscape Nurses News: http://www.medscape.com/viewarticle/499978

• Mayo Clinic. Stroke.(2001-2012). Retrieved March 30, 2012, from http://www.mayoclinic.org/medicalprofs/stroke-prevention.html

• Miffin, H. (2007). The American Heritage Medical Dictionary. Boston, MA: Houghton Mifflin Company.

• National Institutes of Neurological Disorders and Stroke. (2012, January 9th). Brain Basics:Preventing Stroke. Retrieved March 15th, 2012, from National Institutes of Neurological Disorders and Stroke: http://www.ninds.nih.gov/disorders/stroke/preventing_stroke.htm

• National Heart Lung and Blood Institute Explore Stroke. (2011, August). What is a Stroke? Retrieved April 22th, 2012, from National Heart Lung and Blood Institute: http://www.nhlbi.nih.gov/health/health-topics/topics/stroke/causes/html 

• Porth, C. M., & Matfin, G. (2009). Pathophysiology Concepts of Altered Health States 8th Edition. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins.

• Wikipedia. (2011, August 21). Retrieved April 22, 2011, from Lipohyalinosis: http://en.wikipedia.org/wiki/Lipohyalinosis