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Myocardial infarction is the leading cause of death in the United States.
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Americans have more than 1.2 million heart attacks annually and up to 40% of patients die from it.
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Stroke is the third leading cause of death in the United States
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More than 600,000 Americans each year will have a stroke.
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approx 50,000 will have a ministroke (transient ischemic attack)
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Nearly 25% of patients will have a second stroke within 5 years of the first stroke.
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Cardiovascular disease is the number one cause of death in Canada.
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The primary causes of death due to all cardiovascular disease in Canada are
- Acute myocardial infarction (27%)
- Cerebral vascular disease (20%)
- Ischemic heart disease (27%)
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strokes occur when brain cells are deprived of oxygen and are damaged by sudden bleedin in the brain. types of strokes:
- ischemic strokes
- anoxia
- thrombotic stroke
- embolic stroke
- hemorrhage stroke
- transient ischemic attacks
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ischemic strokes account for 80% of all strokes and are caused by sudden oxygen deprivation
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anoxia (absence of oxygen) occurs when arteries are obstructed and is the cause of brain infarcts
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thrombotic stroke is caused by an enlarged thrombus or blood clot
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embolic stroke is caused by an embolus (travelling clot) or plaque that has been dislodged
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blood clots (thrombi, emboli) are the most common cause of strokes
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hemorrhage strokes account for the remaining 20% of all strokes that are caused by bleeding in the brain
it may be the result of an aneurysm, (a weakened spot of the artery wall that has stretched or burst filling the area with blood and causing damage)
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transient ischemic attacks (TIAs) are also known as mini-strokes.
they typically last only a few minutes and symptoms usually resolve within an hour
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myocardial infarctions produces symptoms that are similar to angina, prompt treatment is essential to persons experiencing symptoms
if symptoms last losnger than 15 mins, emergency assisance should be sought
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stroke and mycardial infarction occur when the blood supply to the brain (stoke) or heart (myocardial infarction) is interrupted
cells become damaged or die when they are deprived of oxygen and nutrients
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chronic inflammation of arteries that supply the heart and brain can also lead to stroke and MI because vascular inflammation is a cause of athersclerosis
artherosclerosis can block bloodflow through arteries
atherothrombosis can also cause clogged arteries
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the risk for chronic vascular inflammation increases with age
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risk factors for stroke and MI are categorized as modifiable and nonmodifiable
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nonmodifiable risk factors:
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modifiable risk factors:
- smoking
- heavy alcohol consumption
- diet high in cholesterol
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diseases that can increase risk for stroke and myocardial infarction
- diabetes
- hyperthyperlipidemia
- atrial fibrillation
- infection
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drugs administered to prevent stroke and myocardial infarction control the buildup of lipids and plaques to reduce the formation of blood clots
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drugs that control hemostasis (the process of stoppping the flow of blood) can prevent artherothrombosis and complications associated with the formation of blood clots in arteries
if clots form in an artery and obstruct the supple of blood and oxygen to the brain and heart, stroke and mycardial infarction may occur
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drugs that control the rate of clot formation and clot dissolution are classified as antithrombotics and can prevent stroke and myocardial infarction
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antithrombotic drugs include:
- agents that inhibit platelets
- anticoagulants, which lessen coagulation
- fibrinolytic agents, which dissolve clots
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role of platelets in clot formation
- cluster at the site of injury
- stick to damaged cell wall (adhesion)
- activated by natural substances in the blood such as thromoxane A2 (TXA2), thrombin, and collagen
- activated platelets attract more platelets to region (aggregation)
- fibrin combines with the platelets to strengthen the clot
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antiplatelet drugs interfere with steps in the clot formation process
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although aspirin is a nonprescription drug it is effective for the treatment of post-myocardial infarction and stroke.
- acts as antiplatelet
- blocks the enzyme COX, reducing plaque formation
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abciximab is a glycoprotein IIb/IIIa inhibitor
- blocks the pathwayof platelet aggregation
- only parenteral antiplatelet drug
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ticloidine and clopidogrel
- interferes with platelet adhesion and aggregation
- decreases the concentration of fibrinogen
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dipyradamole
- inhibits platelet aggregation
- is a coronary vasodilator
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antiplatelets should not be combined with anticoagulants without medical supervision
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nonprescription drugs such as NSAIDS (e.g., ibuprofen), vitamin supplements (fish oil), and herbs (feverfew, garlic, ginger) can also cause interactions
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heparin is an anticoagulant that is derived from pig intestines and cow lungs
LMWH are produced by separating the heparin fragments
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heparin and low-molecular-weight-heparins (LMWH) prevent formation of clot
- treat deep vein thrombosis (DVT)
- early treatment of acute myocardial infarction and unstable angina
- prevention of pulmonary embolism
- prevention of secondary myocardial infarction
- prevent clotting in indwelling catheters
- prevent clotting is devices used in surgery
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warfarin is an orally administered anticoagulant
- used to prevent pulmonary embolism
- throbic and embolic stroke
- acute myocardial infarction
- atrial fibrillatin
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tech note!
warfarin is the active ingredient in rodent poisons!
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the effectiveness of warfarin may be decreased by consumption of foods rich in vitamin K and nutritional supplements containing vitamin K
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