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Coronary Artery Disease | 마이메르시 MyMerci
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Coronary Artery Disease

NCLEX Review Guide: Coronary Artery Disease

Pathophysiology of Coronary Artery Disease

Atherosclerosis Development

  • Coronary Artery Disease (CAD) develops when atherosclerotic plaque accumulates in the coronary arteries, causing narrowing of the vessel lumen and decreased blood flow to the myocardium. The process begins with endothelial damage, followed by lipid accumulation, inflammatory cell infiltration, and smooth muscle cell proliferation.
  • Plaque formation progresses through several stages from fatty streaks (early lesions) to complex atheromas with fibrous caps that may rupture and cause acute coronary syndromes.

Key Points

  • Atherosclerosis is a progressive inflammatory process, not simply fat deposition.
  • Plaque rupture is the primary mechanism for acute coronary syndromes.

Myocardial Oxygen Supply and Demand

  • CAD creates an imbalance between myocardial oxygen supply and demand. When coronary blood flow is restricted by atherosclerotic lesions, the heart cannot receive adequate oxygen during increased workload, resulting in myocardial ischemia.
  • Factors increasing myocardial oxygen demand include increased heart rate, contractility, afterload (blood pressure), and ventricular wall tension, while oxygen supply depends on coronary blood flow, hemoglobin concentration, and arterial oxygen saturation.

Key Points

  • Angina occurs when oxygen demand exceeds supply to the myocardium.
  • Treatment aims to either increase oxygen supply or decrease demand.

Risk Factors and Prevention

Modifiable vs. Non-modifiable Risk Factors

Modifiable Risk Factors Non-modifiable Risk Factors
Hypertension Age (men >45, women >55)
Dyslipidemia (↑LDL, ↓HDL) Male gender
Diabetes mellitus Family history of premature CAD
Tobacco use Genetic predisposition
Obesity Post-menopausal status
Sedentary lifestyle
Poor diet/high saturated fat intake
Stress

Key Points

  • NCLEX questions often focus on identifying modifiable risk factors for patient education.
  • Multiple risk factors have a synergistic, not just additive, effect on CAD risk.

Primary and Secondary Prevention Strategies

  • Primary prevention focuses on preventing CAD development through lifestyle modifications and risk factor management in individuals without established disease. This includes regular exercise (minimum 150 minutes of moderate-intensity activity weekly), heart-healthy diet, smoking cessation, and management of hypertension, diabetes, and dyslipidemia.
  • Secondary prevention aims to prevent disease progression and complications in patients with established CAD through aggressive risk factor modification, medication therapy (antiplatelet agents, statins, beta-blockers, ACE inhibitors), and cardiac rehabilitation programs.

Key Points

  • Lifestyle modifications are fundamental to both primary and secondary prevention.
  • Secondary prevention requires more aggressive pharmacological intervention.

Clinical Manifestations and Assessment

Types of Angina

Type of Angina Characteristics Pathophysiology Clinical Significance
Stable Angina Predictable, occurs with exertion, relieved by rest or nitroglycerin within 5 minutes Fixed atherosclerotic lesion causing temporary ischemia Indicates CAD but stable plaque
Unstable Angina Increasing frequency, severity, duration; occurs at rest; poor response to nitroglycerin Partially disrupted plaque with non-occlusive thrombus Medical emergency; risk of MI
Prinzmetal's (Variant) Angina Occurs at rest, often at night, cyclic pattern Coronary artery spasm ST elevation during episodes
Microvascular Angina Chest pain with normal coronary arteries Dysfunction of small coronary vessels More common in women

Key Points

  • Unstable angina is part of the acute coronary syndrome spectrum and requires immediate intervention.
  • The pattern and characteristics of angina help determine the underlying pathology and treatment approach.

Clinical Assessment of CAD

  • Assessment begins with a thorough history focusing on chest pain characteristics using the PQRST method (Provocation/Palliation, Quality, Region/Radiation, Severity, Timing). Classic angina presents as substernal pressure or squeezing that radiates to the left arm, jaw, or back, is provoked by exertion, and relieved by rest or nitroglycerin.
  • Physical examination may be normal in stable CAD but should assess for signs of heart failure, arrhythmias, or other cardiac abnormalities. Key assessments include vital signs (particularly blood pressure and heart rate), heart and lung sounds, peripheral pulses, and signs of hypoperfusion.

Clinical Scenario:

A 62-year-old male with hypertension and hyperlipidemia reports experiencing substernal chest pressure that radiates to his left jaw when walking uphill. The discomfort resolves within 5 minutes after resting. He rates the pain as 5/10 and describes it as "heavy pressure." This presentation is most consistent with stable angina and warrants further cardiac evaluation.

Key Points

  • Atypical presentations are common in women, elderly, and patients with diabetes (may present with dyspnea, fatigue, or epigastric discomfort).
  • New onset, crescendo, or rest angina requires urgent evaluation for acute coronary syndrome.

Diagnostic Tests for CAD

  • Non-invasive testing includes electrocardiogram (ECG), which may show ST-segment depression or T-wave inversion during ischemic episodes; stress testing (exercise or pharmacological) to provoke ischemia; and imaging studies such as echocardiography, nuclear perfusion scans, or cardiac CT to assess myocardial function and perfusion.
  • Invasive testing primarily involves coronary angiography, the gold standard for diagnosing CAD, which visualizes coronary anatomy and identifies location and severity of stenosis. Laboratory tests include cardiac biomarkers (troponin, CK-MB) to rule out myocardial infarction, and lipid profiles to assess cardiovascular risk.

Key Points

  • A normal resting ECG does not exclude significant CAD.
  • Elevated cardiac biomarkers differentiate unstable angina from myocardial infarction.

Pharmacological Management

Antiplatelet and Anticoagulant Therapy

  • Antiplatelet agents prevent platelet aggregation and thrombus formation. Aspirin (81-325 mg daily) is first-line therapy for all CAD patients without contraindications. P2Y12 inhibitors (clopidogrel, ticagrelor, prasugrel) are added for acute coronary syndromes and post-percutaneous coronary intervention (PCI).
  • Anticoagulants such as unfractionated heparin, low-molecular-weight heparin, or direct oral anticoagulants may be used in specific scenarios like acute coronary syndromes, atrial fibrillation with CAD, or mechanical heart valves. These medications prevent thrombin formation and fibrin clot development.

Important Alert: Monitor for bleeding complications with antiplatelet and anticoagulant therapy. Teach patients to report any unusual bleeding, bruising, black stools, or hemoptysis immediately. Dual antiplatelet therapy significantly increases bleeding risk.

Key Points

  • Low-dose aspirin is recommended for most CAD patients for secondary prevention.
  • Duration of dual antiplatelet therapy depends on stent type and bleeding risk.

Anti-ischemic Medications

  • Nitrates (nitroglycerin, isosorbide) cause venous and arterial vasodilation, reducing preload and afterload, thereby decreasing myocardial oxygen demand and increasing coronary blood flow. Short-acting forms treat acute angina, while long-acting preparations prevent anginal episodes.
  • Beta-blockers (metoprolol, carvedilol, atenolol) reduce heart rate, contractility, and blood pressure, decreasing myocardial oxygen demand. They improve symptoms and reduce mortality post-MI. Calcium channel blockers (amlodipine, diltiazem, verapamil) cause vasodilation and reduce myocardial contractility, particularly useful when beta-blockers are contraindicated.

Medication Memory Aid: Anti-ischemic Medications

"N-B-C" therapy for CAD:

  • Nitrates: Dilate vessels, reduce preload/afterload
  • Beta-blockers: Reduce heart rate and contractility
  • Calcium channel blockers: Vasodilate and reduce contractility

Key Points

  • Nitrates are contraindicated with phosphodiesterase inhibitors (sildenafil, tadalafil) due to severe hypotension risk.
  • Beta-blockers should not be abruptly discontinued as this may precipitate rebound angina or MI.

Lipid-Lowering Therapy

  • Statins (atorvastatin, rosuvastatin, simvastatin) inhibit HMG-CoA reductase, reducing cholesterol synthesis and LDL levels. They have pleiotropic effects including plaque stabilization, improved endothelial function, and anti-inflammatory properties, reducing cardiovascular events and mortality in CAD patients.
  • Additional lipid-lowering agents include ezetimibe (blocks intestinal cholesterol absorption), PCSK9 inhibitors (evolocumab, alirocumab) for refractory hyperlipidemia, bile acid sequestrants, and fibrates for hypertriglyceridemia. Combination therapy may be necessary to reach target lipid levels in high-risk patients.

Important Alert: Monitor for statin side effects including myalgias, elevated liver enzymes, and rarely rhabdomyolysis. Patients should report unexplained muscle pain, tenderness, or weakness, especially if accompanied by fever or malaise.

Key Points

  • High-intensity statins are recommended for secondary prevention in CAD patients.
  • Target LDL levels for CAD patients are typically <70 mg/dL for very high-risk patients.

Interventional and Surgical Management

Percutaneous Coronary Intervention (PCI)

  • PCI involves catheter-based techniques to restore coronary blood flow, typically including balloon angioplasty followed by stent placement. Drug-eluting stents release antiproliferative medications to prevent restenosis, while bare-metal stents provide structural support without medication.
  • Indications include acute coronary syndromes (primary PCI for STEMI), stable angina unresponsive to medical therapy, or significant coronary stenosis with evidence of ischemia. Complications include bleeding, vascular access complications, contrast nephropathy, stent thrombosis, and restenosis.

    PCI Procedure Steps:

  1. Vascular access obtained (femoral or radial artery)
  2. Coronary angiography performed to identify lesions
  3. Guidewire passed across stenosis
  4. Balloon catheter advanced and inflated to dilate narrowing
  5. Stent deployed to maintain vessel patency
  6. Final angiography confirms results
  7. Hemostasis achieved at access site

Key Points

  • Primary PCI is preferred for STEMI when available within 90 minutes of first medical contact.
  • Post-PCI care includes dual antiplatelet therapy, monitoring for complications, and cardiac rehabilitation.

Coronary Artery Bypass Grafting (CABG)

  • CABG involves creating alternative conduits for coronary blood flow using autologous vessels (internal mammary arteries, saphenous veins, radial arteries) to bypass coronary stenoses. The internal mammary artery has superior long-term patency compared to venous grafts.
  • Indications include left main coronary artery disease, three-vessel disease (especially with reduced ejection fraction or diabetes), complex lesions unsuitable for PCI, or failed PCI. CABG may provide more complete revascularization and better long-term outcomes in complex CAD.

Clinical Scenario:

A 68-year-old diabetic male with three-vessel coronary disease including 90% stenosis of the left main coronary artery and an ejection fraction of 40% is evaluated for revascularization. The heart team recommends CABG over PCI due to the anatomical complexity, diabetes, and reduced ejection fraction. This approach is supported by evidence showing improved long-term outcomes with surgical revascularization in this high-risk population.

Key Points

  • Postoperative nursing care focuses on hemodynamic stability, pain management, respiratory care, and preventing complications.
  • Sternal precautions are essential post-CABG to prevent dehiscence (no pushing, pulling, or lifting >10 pounds for 6-8 weeks).

Comparing Revascularization Options

Aspect Percutaneous Coronary Intervention Coronary Artery Bypass Grafting
Invasiveness Minimally invasive, catheter-based Major open surgery (or minimally invasive techniques)
Recovery time Short (1-2 days hospitalization) Longer (5-7 days hospitalization, 6-12 weeks recovery)
Best suited for 1-2 vessel disease, discrete lesions Left main disease, 3-vessel disease, complex anatomy
Durability May require repeat procedures Better long-term patency, especially with arterial grafts
Diabetes impact Less favorable outcomes Preferred in diabetic patients with multivessel disease
Complications Stent thrombosis, restenosis, access site complications Stroke, infection, bleeding, respiratory complications

Key Points

  • The heart team approach (cardiologist, cardiac surgeon, and other specialists) is recommended for revascularization decisions.
  • Patient factors (age, comorbidities, preferences) and coronary anatomy both influence the choice between PCI and CABG.

Nursing Management and Patient Education

Acute Care Nursing Interventions

  • Nursing care for acute coronary syndromes includes continuous cardiac monitoring, oxygen administration if saturation <94%, establishing IV access, administering prescribed medications (aspirin, anticoagulants, antiplatelet agents, nitrates, beta-blockers), and frequent assessment of vital signs, chest pain, and hemodynamic status.
  • Pain management is crucial using nitroglycerin and morphine as appropriate. Nurses should monitor for complications including arrhythmias, heart failure, cardiogenic shock, and mechanical complications. Serial ECGs and cardiac biomarkers help evaluate treatment effectiveness and disease progression.

Important Alert: In acute coronary syndromes, the "5 Rights" of immediate care include: Right position (semi-Fowler's), Right assessment (vital signs, pain, ECG), Right oxygen (to maintain SpO2 >94%), Right medications (aspirin, nitroglycerin, etc.), and Right monitoring (continuous cardiac monitoring).

Key Points

  • Rapid recognition and intervention are essential in acute coronary syndromes.
  • Document pain characteristics, interventions, and response to treatment thoroughly.

Patient Education for CAD Management

  • Comprehensive patient education includes medication management (names, purposes, dosages, administration times, side effects), symptom recognition (when to use nitroglycerin vs. when to call 911), and risk factor modification (smoking cessation, diet, exercise, stress management).
  • Dietary education should emphasize a heart-healthy diet (Mediterranean or DASH diet) low in saturated fat, trans fat, and sodium, while rich in fruits, vegetables, whole grains, and lean proteins. Physical activity recommendations include gradually increasing to 150 minutes of moderate-intensity exercise weekly, with cardiac rehabilitation for structured exercise and education.

Patient Education Memory Aid: The "ABCDES" of CAD Management

  • Aspirin and Antiplatelet therapy adherence
  • Blood pressure control
  • Cholesterol management
  • Diet modification and Diabetes control
  • Exercise regularly
  • Smoking cessation

Key Points

  • Use teach-back method to confirm patient understanding of complex medication regimens.
  • Involve family members in education sessions to improve adherence and support.

Cardiac Rehabilitation

  • Cardiac rehabilitation is a comprehensive, multidisciplinary program that includes supervised exercise training, risk factor modification, psychosocial support, and education. It's indicated for patients after MI, coronary revascularization (PCI or CABG), stable angina, or heart failure.
  • The program typically consists of three phases: inpatient (Phase I), early outpatient (Phase II), and maintenance (Phase III). Benefits include improved functional capacity, reduced symptoms, improved lipid profiles, enhanced psychological well-being, and reduced morbidity and mortality.

Key Points

  • Despite proven benefits, cardiac rehabilitation remains underutilized, particularly in women and minorities.
  • Nurses play a crucial role in referring eligible patients and encouraging participation.

Commonly Confused Points

Angina vs. Myocardial Infarction

Feature Angina Myocardial Infarction
Pathophysiology Temporary myocardial ischemia without cell death Prolonged ischemia leading to myocardial necrosis
Pain duration Usually <15 minutes, relieved by rest/NTG Usually >30 minutes, unrelieved by rest/NTG
Associated symptoms May have mild diaphoresis, dyspnea Often severe diaphoresis, nausea, vomiting, extreme fatigue
Cardiac biomarkers Normal Elevated (troponin, CK-MB)
ECG changes May show ST depression during pain, normalizes after May show ST elevation or depression, Q waves, persistent changes
Treatment urgency Urgent evaluation Medical emergency requiring immediate intervention

Key Points

  • The key distinction is reversible ischemia (angina) versus myocardial necrosis (MI).
  • Unstable angina and NSTEMI may present similarly but differ in biomarker elevation.

Differentiating Types of Acute Coronary Syndromes

Feature Unstable Angina NSTEMI STEMI
Definition Unstable anginal symptoms without myocardial necrosis Myocardial necrosis without ST-segment elevation Myocardial necrosis with ST-segment elevation
Biomarkers Normal troponin Elevated troponin Elevated troponin
ECG findings ST depression, T-wave inversion, or normal ST depression, T-wave inversion, or normal ST elevation in contiguous leads
Pathophysiology Non-occlusive thrombus or severe stenosis Partial coronary occlusion Complete coronary occlusion
Initial treatment Antiplatelet, anticoagulant, anti-ischemic therapy Antiplatelet, anticoagulant, anti-ischemic therapy Immediate reperfusion (PCI or fibrinolysis)
Timing of intervention Early invasive strategy for high-risk features Early invasive strategy for high-risk features Emergency reperfusion (door-to-balloon <90 min)

Key Points

  • Unstable angina and NSTEMI are managed similarly initially, differentiated by biomarker results.
  • STEMI requires the most urgent intervention to restore coronary flow.

Nitroglycerin Administration vs. Other Medications

Feature Sublingual Nitroglycerin Beta-Blockers Calcium Channel Blockers
Onset of action 1-3 minutes Variable (30 min to hours) Variable (30 min to hours)
Use in acute angina First-line treatment Not for acute relief Not for acute relief
Administration Sublingual or spray, can repeat q5min x3 Oral (or IV in certain settings) Oral
Major side effect Hypotension, headache Bradycardia, bronchospasm Peripheral edema, constipation
Contraindications Recent PDE5 inhibitor use, severe hypotension Severe bradycardia, heart block, asthma Heart failure (verapamil, diltiazem)
Patient instructions Sit/lie down when taking, call 911 if no relief after 3 doses Take regularly, do not abruptly discontinue Take regularly, monitor for edema

Key Points

  • Only nitroglycerin is appropriate for immediate angina relief; other medications are for prevention.
  • Patients should call emergency services if chest pain is unrelieved after 3 nitroglycerin doses 5 minutes apart.

Study Tips and NCLEX Strategies

Priority Setting in CAD Questions

  • NCLEX questions about CAD often test your ability to prioritize care. Remember to apply Maslow's hierarchy and the ABCs (Airway, Breathing, Circulation). For a patient with chest pain, addressing oxygenation and pain relief takes priority over patient education or laboratory tests.
  • When presented with multiple patients, prioritize based on stability and acuity. A patient with new-onset chest pain and diaphoresis requires immediate attention compared to a stable patient with chronic angina who needs medication teaching.

Priority Setting Framework for CAD

  1. Life-threatening conditions (acute chest pain, hemodynamic instability)
  2. Potential for deterioration (new-onset symptoms, changing patterns)
  3. Symptom management (stable angina, medication side effects)
  4. Education and prevention (risk factor modification, medication adherence)

Key Points

  • In CAD scenarios, circulation issues (chest pain, hypotension) often take priority.
  • Differentiate between emergency situations requiring immediate intervention and stable conditions where education is appropriate.

Medication-Related Questions

  • NCLEX frequently tests knowledge of cardiovascular medications, particularly antiplatelet agents, anticoagulants, statins, beta-blockers, and nitrates. Focus on understanding mechanism of action, major side effects, contraindications, and nursing implications rather than memorizing every detail.
  • For drug interaction questions, remember key high-risk combinations: nitrates with PDE5 inhibitors (severe hypotension), NSAIDs with anticoagulants (bleeding risk), and certain statins with medications metabolized by CYP3A4 (increased statin levels and myopathy risk).

Common Pitfall: Don't confuse the timing of medication administration. Sublingual nitroglycerin is for acute angina relief, while oral nitrates, beta-blockers, and calcium channel blockers are for prevention. NCLEX often tests this distinction in questions about patient education.

Key Points

  • Focus on patient teaching points and safety monitoring for each medication class.
  • Know the contraindications for common CAD medications, especially for emergency situations.

Diagnostic Test Interpretation

  • NCLEX questions may ask about appropriate nursing actions based on diagnostic test results. For cardiac biomarkers, know that troponin is the most specific marker for myocardial injury, typically rising within 3-4 hours of injury, peaking at 24-48 hours, and remaining elevated for 7-14 days.
  • For ECG interpretation questions, focus on recognizing basic patterns rather than detailed analysis. Key patterns include ST-segment elevation (STEMI), ST-segment depression or T-wave inversion (ischemia), and Q waves (prior infarction). Understand appropriate nursing actions based on these findings.

ECG Changes in Ischemia/Infarction

  • ST elevation: Transmural ischemia or infarction (STEMI)
  • ST depression: Subendocardial ischemia
  • T-wave inversion: Ischemia
  • Q waves: Necrosis/infarction (may be permanent)
  • Location clues:
    • Leads II, III, aVF: Inferior wall
    • Leads V1-V4: Anterior wall
    • Leads I, aVL, V5-V6: Lateral wall

Key Points

  • Focus on nursing implications of test results rather than detailed interpretation.
  • Understand which findings require immediate notification of the provider.

Summary of Key Points

  • Pathophysiology: CAD results from atherosclerotic plaque formation in coronary arteries, creating an imbalance between myocardial oxygen supply and demand. Plaque rupture and thrombosis lead to acute coronary syndromes.
  • Clinical Presentation: Angina manifests as substernal chest discomfort often radiating to the arm, jaw, or back, triggered by exertion and relieved by rest or nitroglycerin. Unstable patterns or symptoms at rest require urgent evaluation.
  • Diagnostic Approach: Assessment includes thorough history, ECG, cardiac biomarkers, and stress testing with imaging as appropriate. Coronary angiography remains the gold standard for defining coronary anatomy.
  • Pharmacological Management: Includes antiplatelet therapy, anticoagulants, nitrates, beta-blockers, calcium channel blockers

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