Coronary Artery Disease & Acute Coronary Syndrome
ST Segment depression= Ischemia
T wave inversion = Ischemia
Coronary Artery Disease
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An abnormal
condition that may
affect the heart’s arteries and produce various pathological effects,
especially reduction in flow of oxygen and nutrients to the
myocardium
Atherosclerosis is a major cause of CAD
o Begins as soft deposits of fat that harden with age
o Referred to as “hardening of arteries”
o Can occur in any artery in the body
o Atheromas (fatty deposits): Preference for the coronary arteries
A, Damaged endothelium.
B, Diagram of fatty streak
and lipid core formation.
C, Diagram of fibrous
plaque. Raised plaques are
visible: Some are yellow,
others are white.
D, Diagram of complicated
lesion: Thrombus is red,
collagen is blue. Plaque is
complicated by red thrombus
deposition.
Vessel Occlusion with Collateral Circulation
A, Open, functioning coronary artery.
B, Partial coronary artery closure with collateral
circulation being established.
C, Total coronary artery occlusion with collateral
circulation bypassing the occlusion to supply blood to
the myocardium.
Risk Factors for CAD
Nonmodifiable Risk Factors
Modifiable Risk Factors
- Serum lipids (Cholesterol greater
- Increasing age
- Gender: Men greater than
than 5.0 mmol/L or a fasting
women until 65 years of
triglyceride level greater than 3.7
age
mmol/L)
- *Hypertension (a BP > 140/90 mm Hg
- Ethnicity: whites’
greater risk than blacks
or >130/80 mm Hg if the patient has
- Family history of heart
diabetes or chronic kidney disease)
- Diabetes
disease
- Tobacco use (2-6x higher)
- Genetic predisposition
- Physical inactivity
- Obesity [(BMI) of >30 kg/m2 and a
waist circumference ≥102 cm (40
inches) for men and ≥88 cm (35
inches) for women]
Serum Lipids
• Healthy serum lipid panel includes:
o ↓ Total cholesterol
o ↓ LDL
o ↑ HDL
o ↓ Triglycerides
Improving Serum Lipids
• Total cholesterol and LDL
o ↓ Total fat intake and saturated fats
• HDL
o ↑ Physical activity and exercise
• Triglycerides
o ↓ or eliminate alcohol and simple sugars
Management of CAD: Lipid-lowering drug therapy
• Include drug classes that:
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o Restrict lipoprotein production: Ex. Statins, niacin
o Increase lipoprotein removal: Ex. Bile acid sequestrants
o Decrease Cholesterol absorption: Ex. Ezetimibe (Ezetrol)
Antiplatelet therapy
o Low dose Aspirin or Clopidogrel (Plavix)
Chronic Stable Angina
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Pain
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usually lasts 3-5 mins
Subsides when the precipitating factor is relieved
Pain at rest is unusual
ECG reveals ST-segment depression and/or T-wave inversion
Location of Pain During Angina & MI
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Although most of the pain experienced
by people with angina appears
substernally, the sensation may occur
in the neck or may radiate to various
locations, including the jaw and
shoulders, and down the arms.
Often people will complain of pain
between the shoulder blades and will
dismiss it as not being heart
related.
Chronic Stable Angina Management (ONAM: Oxygen, Nitrates, Aspirin,
Morphine)
• Acute interventions for anginal attack
o Have client rest or sit immediately
o Administer Oxygen
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o Assess vitals, pulse oximetry
o 12-lead ECG
o Prompt pain relief with a nitrate first followed by an opioid
analgesic, if needed
o Auscultation of heart sounds
Ask the patient to describe the pain and to rate it on a scale of 0
to 10 before and after treatment to evaluate the effectiveness of the
interventions.
Diagnostic Studies
o Health history/physical examination
o Laboratory studies
o 12-lead ECH
o Chest x-ray
o Echocardiogram
o Exercise stress test
o Cardia catheterization/coronary angiography (Diagnostic)
o Coronary revascularization: percutaneous coronary intervention
(PCI)
 Balloon angioplasty
 Stent
Acute Coronary Syndrome (ACS)
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When
ischemia is
prolonged and is not immediately reversible, acute coronary syndrome
(ACS) develops.
Clinical Manifestations of ACS
• Unstable angina
o Changes in usual pattern
o New in onset
o Occurs at rest
o Has a worsening pattern
• UA is unpredictable and represents a medical emergency
Unstable Angina & MI
Diagnostic Studies
• Detailed health history and physical
• 12-lead ECG: changes in QRS complex, ST segment elevation
• Serum cardiac markers
• Coronary angiography
• Others: exercise stress testing, echocardiogram
Elevated ST segment during an MI is referred to as an ST-segment elevation
MI (STEMI).
Serum Cardiac Markers After MI
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CK-MB begins to rise about 6 hours after symptoms onset, peaks in
about 18 hours, and returns to baseline within 24-36 hours after MI
Troponin is detectable within hours (average 4-6hours), peaks at 1024 hours, and can be detected for up to 10-14 days
Myoglobin begins to rise within 2 hours and peaks in 3-15 hours
Serum Cardiac Marker After MI
• Troponin- cardiac-specific
o Detectable within one hour of myocardial injury, high
specificity at 3 to 6 hours, peak at 24 to 48 hours and return
to baseline over 5 to 14 days
• CK-MB- cardiac-specific
o Levels rise 4 to 6 hours after symptoms onset, peak in 18 to 24
hours, and return to baseline within 3 days after MI
• Myoglobin- cardiac and skeletal muscle specific
o Rise within 30 to 60 min after cardiac injury but return to
baseline within 24 hours of an MI
Acute Coronary Syndrome
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Result:
o Partial occlusion of coronary artery: UA or NSTEMI
o Total occlusion of coronary artery: STEMI
Myocardial Infarction (MI)
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Result of
sustained ischemia
(>20mins), causing irreversible myocardial cell death (necrosis)
Necrosis of entire thickness of myocardium takes 4-6 hours
Infarctions are usually describing according to the location of
damage (ex. Anterior, inferior, lateral, posterior wall infarction)
Myocardial Infarction from Occlusion
• Occlusion of the left anterior descending coronary artery, resulting
in a myocardial infarction.
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Termed the ‘widow maker’ MI because it affects the left ventricle
which is responsible for pumping the blood into the systemic
circulation.
Acute myocardial infarction in the
posterolateral wall of the left
ventricle. This is demonstrated by
the absence of staining in the
areas of necrosis (white arrow).
Note the scarring from a previous
anterior wall myocardial
infarction (black arrow).
Full-Thickness MI
• Myocardial infarction involving the full thickness of the left
ventricular wall.
Myocardial Infarction
• The degree of altered function depends on the area of the heart
involved and the size of the infarct
• Contractile function of the heart is disrupted in areas of myocardial
necrosis
• Most Mis involve the left ventricle (LV)
• The severity of an MI is determined by the location, if it is a
partial or total occlusion (NSTEMI or STEMI) and how many layers of
the myocardium is damaged.
• Pain
o Total occlusion  anerobic metabolism and lactic acid
accumulation  severe, immobilizing chest pain not relieved by
rest, position change, or nitrate administration
o Described as heaviness, constriction, tightness, burning,
pressure, or crushing
o Common locations: substernal, retrosternal, or epigastric areas;
pain may radiate to neck, jaw, arms
• Stimulation of Sympathetic NS results in
o Release of glycogen
o Diaphoresis
o Vasocontraction of peripheral blood vessels
o Skin: ashen, clammy, and/or cool to touch
• Cardiovascular
o Initially, ↑ HR and BP, then ↓ BP (secondary to ↓ in CO)
o Crackles
o Jugular venous distension
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o Abnormal heart sounds: S3 or S4 or New murmur
Nausea and vomiting
o Can result from reflex stimulation of the vomiting center by
severe pain
Fever
o Systemic manifestation of the inflammatory process caused by
cell death
Acute Coronary Syndrome Collaborative Care
• Emergency management
o Initial interventions (ONAM)
 Establish an IV, oxygen, sublingual NTG, Aspirin, Morphine
sulphate
o Ongoing monitoring of VS, lung and heart sounds
• Emergency PCI (ideally within 90 mins)
o PCI= percutaneous coronary intervention
o Treatment of choice for confirmed MI
o Balloon angioplasty + drug-eluting stents
• Fibrinolytic therapy (within 6 hours)
o IV Alteplase/Activas recombinant or tissue plasminogen activator
(t-PA)
o Best marker of reperfusion: return of ST segment to baseline
o Rescue PCI if thrombolysis fails
o Major Complication: BLEEDING
• Coronary surgical revascularization
o Failed medical management
o Presence of left main coronary artery or three-vessel disease
o Not a candidate for PCI (Ex. Lesions are long or difficult to
acess)
o Failed PCI with. Ongoing chest pain
o History of diabetes
o Coronary revascularization with CABG surgery is recommended for
these patients
o Coronary artery bypass graft (CABG) surgery
 Requires sternotomy and cardiopulmonary bypass (CPB)
 Uses arteries and veins for grafts
CABG Surgery
The distal end of the left internal
mammary artery is grafted below the
area of blockage in the left
anterior descending artery. The
proximal end of the saphenous vein
is grafted to the aorta, and the
distal end is grafted below the
area of blockage in the right
coronary artery.
Myocardial Infarction Healing Process
• Within 24 hours, leukocytes infiltrate the area of cell death
• Enzymes are released from the dead cardiac cells (important indictors
of MI)
• Proteolytic enzymes of neutrophils and macrophages remove all
necrotic tissue by second or third day
• Development of collateral circulation improves areas of poor
perfusion
• Necrotic zone identifiable by ECG changes an nuclear scanning
• 10-14 days after MI, scar tissue is still weak and vulnerable to
stress
• By 6 weeks after MI, scar tissue has replaced necrotic tissue
o Area is said to be healed, but less compliant
• Ventricular remodelling
o Normal myocardium will hypertrophy and dilate in an attempt to
compensate for the infracted muscle
Complications of MI
• Dysrhythmias
o Most common complication
o Present in 80% of MI patients
o Most common cause of death in the prehospital period
o Life-threatening dysrhythmias seen most often with anterior MI,
HF, or shock
• Heart Failure
o A complication that occurs when the pumping power of the heart
has diminished
• Cardiogenic Shock
o Occurs when inadequate oxygen and nutrients are supplied to the
tissues because of severe LV failure
o Requires aggressive management
ACS Collaborative Care
• Nutritional therapy
o Initially NPO
o Progress to: Low salt, Low saturated fat, Low cholesterol
• Rest and comfort
o Balance rest and activity
o Begin cardiac rehabilitation
• Drug Therapy
o Drug therapy
o IV nitroglycerin
o Morphine sulphate
o β-Adrenergic blockers
o Angiotensin-converting enzyme inhibitors
o Antidysrhythmia drugs
o Cholesterol-lowering drugs
o Stool softeners
ACS Nursing Management
• Anxiety
• Emotional and behavioural reaction
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Maximize patient’s social support systems.
Consider open visitation.
Ambulatory and home care
Patient and caregiver teaching
Physical exercise
Resumption of sexual activity
Evaluation
o Relief of pain
o Preservation of myocardium
o Immediate and appropriate treatment
o Effective coping with illness-associated anxiety
o Participation in a rehabilitation plan
o Reduction of risk factors
Questions
• Which type of MI causes more damage to the myocardium?
o STEMI
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How many minutes of sustained ischemia does it take to cause
irreversible myocardial cell death (necrosis)?
o Approx. 20 mins
o “Time is muscle” for MI’s
o “Time is brain” for strokes
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How many hours does it take for necrosis of the entire thickness of
the myocardium?
o 4-6 hours
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After an MI, how many weeks does it take for scar tissue to replace
the necrotic tissue?
o 6 weeks
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The patient receives IV morphine for chest pain. Which of the
following results are the intended effects of morphine? Select all
that apply.
o A. Reduce myocardial oxygen consumption
o B. Promotes reduction in respiratory rate
o C. Reduces blood pressure and heart rate
o D. Reduces anxiety and fear
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A patient presents to the emergency department with an MI that
damages the full thickness of the myocardium. What would the ECG
changes reflect for this patient?
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2nd one
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After a coronary angiogram through the right femoral artery, the
nurse is not able to palpate the right pedal pulse. What is the
nurse’s first action?
o A. Elevate the legs
o B. Change the IV rate
o C. Use a doppler to assess the pulse
o D. Call the doctor
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Which of the following medications would a patient have to take for
at least a year following an angioplasty to the RCA?
o A. Warfarin and ASA
o B. Heparin and ASA
o C. Clopidogrel and ASA
o D. ASA only