Myocardial Infarction: Acute MI
-- irreversible myocardial necrosis that results from an abrupt decrease or total cessation of coronary
blood flow to a specific area of the myocardium.
-- ST elevation on 12 lead ECG
~ STEMI (Normally a clot)
~ NSTEMI (normally a plaque)
-- Mechanism of action:
1. Plaque rupture
2. New Coronary Artery thrombosis
3. Coronary artery spasm
~ Give BB/CCB to relax and reduce spasms. Should not need electricity!
-- Clinical Manifestations:
~ tachycardia with or without ectopy
~ bradycardia (due to SA node injury)
~ Normotension or hypotension (depending on how much damage)
~ Tachypnea (due to hypoxia of heart)
~ Diminished Heart sounds (especially S1)
~ Systolic murmur
~ Crackles ( if in LV failure)
~ Pulmonary edema (frothy sputum)
~ Air hunger/orthopnea
~ Decreased CO, Decreased UO, Decreased peripheral pulses, Slow cap refill
~ Restlessness, confusion, anxiety, agitation, denial, anger
*~ Females and diabetics may have atypical symptoms.
*~ Tx for CP: MONA but not necessarily in that order.
< Put on oxygen immediately.
Myocardial Infarction Cont.
< Determine how many aspirin, if any, they have already used or were given in
ambulance
< Nitroglycerin Second
< Morphine last for pain control and to decrease oxygen demand
TIP: Heart Fail/ure (3 syllables)=== S3
Hy/per/ten/sion (4 syllables) === S4
-- Pathophysiology:
, 1. Zone of Ischemia
~ outer region of infracted myocardium
~ Has viable cells that you want to save!
~ Repolarization of these cells show as an inverted T Wave
< It’s hard to get cells repolarized.
< Inverted T wave can last from a few months to forever.
1. Zone of Injury
~ Injured but still potentially viable tissue
~ Do not fully repolarize because of the deficient blood supply.
~ Have elevation of ST segment.
Example:
2. Zone of Infarction
~ Actual dead muscle. Will never heal. Replaced with scar tissue.
~ Cannot perform any of normal actions of the heart (Cannot conduct electricity,
contract correctly)
~ Pathologic Q Waves (big dip for Q wave)
~ Lack of depolarization from the cardiac surface involved in the MI
Transmural MI
-- Involves all 3 layers of the heart (endocardium, myocardium, & epicardium)== Full thickness MI!
-- Significant ECG changes/ “Q-Wave” MI
-- Categorized by how many layers it damaged and where it happened
12 Lead ECG Changes
-- Alteration in depolarization (QRS complex changes)
-- Alteration in repolarization (ST segment or Q waves change)
-- Location determined by matching changes to leads!
4 major coronary arteries. See picture on slides!
1. Right coronary artery
2. Left main coronary artery
3. Circumflex artery
4. L. anterior descending artery
5.
Know leads of each for TEST!!
-- irreversible myocardial necrosis that results from an abrupt decrease or total cessation of coronary
blood flow to a specific area of the myocardium.
-- ST elevation on 12 lead ECG
~ STEMI (Normally a clot)
~ NSTEMI (normally a plaque)
-- Mechanism of action:
1. Plaque rupture
2. New Coronary Artery thrombosis
3. Coronary artery spasm
~ Give BB/CCB to relax and reduce spasms. Should not need electricity!
-- Clinical Manifestations:
~ tachycardia with or without ectopy
~ bradycardia (due to SA node injury)
~ Normotension or hypotension (depending on how much damage)
~ Tachypnea (due to hypoxia of heart)
~ Diminished Heart sounds (especially S1)
~ Systolic murmur
~ Crackles ( if in LV failure)
~ Pulmonary edema (frothy sputum)
~ Air hunger/orthopnea
~ Decreased CO, Decreased UO, Decreased peripheral pulses, Slow cap refill
~ Restlessness, confusion, anxiety, agitation, denial, anger
*~ Females and diabetics may have atypical symptoms.
*~ Tx for CP: MONA but not necessarily in that order.
< Put on oxygen immediately.
Myocardial Infarction Cont.
< Determine how many aspirin, if any, they have already used or were given in
ambulance
< Nitroglycerin Second
< Morphine last for pain control and to decrease oxygen demand
TIP: Heart Fail/ure (3 syllables)=== S3
Hy/per/ten/sion (4 syllables) === S4
-- Pathophysiology:
, 1. Zone of Ischemia
~ outer region of infracted myocardium
~ Has viable cells that you want to save!
~ Repolarization of these cells show as an inverted T Wave
< It’s hard to get cells repolarized.
< Inverted T wave can last from a few months to forever.
1. Zone of Injury
~ Injured but still potentially viable tissue
~ Do not fully repolarize because of the deficient blood supply.
~ Have elevation of ST segment.
Example:
2. Zone of Infarction
~ Actual dead muscle. Will never heal. Replaced with scar tissue.
~ Cannot perform any of normal actions of the heart (Cannot conduct electricity,
contract correctly)
~ Pathologic Q Waves (big dip for Q wave)
~ Lack of depolarization from the cardiac surface involved in the MI
Transmural MI
-- Involves all 3 layers of the heart (endocardium, myocardium, & epicardium)== Full thickness MI!
-- Significant ECG changes/ “Q-Wave” MI
-- Categorized by how many layers it damaged and where it happened
12 Lead ECG Changes
-- Alteration in depolarization (QRS complex changes)
-- Alteration in repolarization (ST segment or Q waves change)
-- Location determined by matching changes to leads!
4 major coronary arteries. See picture on slides!
1. Right coronary artery
2. Left main coronary artery
3. Circumflex artery
4. L. anterior descending artery
5.
Know leads of each for TEST!!
