Exam 22 - Coronary Artery Disease (CAD)

Coronary Artery Disease (CAD) Overview

• CAD includes conditions that impede blood flow in the coronary arteries
• Atherosclerosis, marked by changes in the artery's intimal lining, is the main cause of artery lumen narrowing
• CAD's severity depends on the obstruction level and number of affected vessels
• Myocardial oxygen demand exceeding supply causes symptoms, where obstructions over 75% in coronary arteries raise death risk

Risk Factors for CAD

• Risk factors are predisposing conditions increasing the chance of cardiovascular disease
• Multiple risk factors compound the overall risk

Non-Modifiable Risk Factors

• Family history is a risk factor, especially with heart issues before age 50
• Age-related physiological changes also elevate risk

Modifiable Risk Factors

• High VLDL and LDL lipid levels, along with low HDL levels are risk factors
• Smoking decreases oxygen supply
• Hypertension, with blood pressure above 140/90 mmHg, increases oxygen consumption
• Physical inactivity reduces heart efficiency
• Obesity increases the heart's workload
• Diabetes damages the arterial intima
• Stress causes catecholamine release and vasoconstriction, thus increasing oxygen consumption
• Type D personality is a psychosocial risk factor

Angina Pectoris

• Angina is a spasmodic, choking chest feeling indicating myocardial ischemia or heart muscle death

Angina Etiology

• Reduced blood flow from vasospasm, stenosis, thrombosis, or atherosclerosis reduces oxygen supply
• Increased heart rate, contractility, afterload, or preload cause greater oxygen consumption/demand
• Hypertension, stress, strenuous activity, and smoking trigger increased cardiac workload

Types of Angina

• Unstable angina features unpredictable, severe discomfort, possibly signaling an impending MI

Angina Clinical Manifestations

• Chest pain is described as heaviness or tightness
• Pain may spread to the left shoulder and arm
• Women could feel pain on the chest's left side, abdomen, mid-back, or scapular region
• Other symptoms include dyspnea, pallor, diaphoresis, faintness, palpitations, and dizziness

Myocardial Infarction (MI)

• MI involves heart muscle cell death, often from a coronary artery obstruction due to plaque or an embolus
• MI Definition: Death of myocardium from inadequate oxygen and arterial blood flow, usually with thrombus (80-90%)
• MI Pathophysiology: Supply-demand problem where cardiac muscle lacks oxygen supply despite ongoing demand; ischemia for 35-45 minutes causes cell damage, impairing heart contraction

MI Clinical Manifestations

• Chest pain is severe, lasts 30+ minutes, and isn't relieved by nitroglycerin
• Men may describe "crushing" pain in the heart region, radiating down the left arm, jaw, or teeth
• Early signs in women include fatigue, sleep issues, shortness of breath, weakness, anxiety, and indigestion
• Patients may express impending death
• Objective signs include rubbing the left arm or pressing a fist against the sternum
• Other signs: hypotension, gray skin, clammy skin, diaphoresis, weak pulse, and dysrhythmias

Diagnostic Tests for Angina Pectoris

• EKG detects transient ischemic changes, indicated by ST segment depression
• Exercise Stress ECG monitors heart function under stress
• Coronary Angiography visualizes coronary arteries for defects or occlusions

Diagnostic Tests for MI

• Cardiac markers are proteins released into circulation due to cardiac cell damage
  • CK-MB rises within 2-3 hours, peaks at 24 hours, and normalizes in 24-40 hours
  • Myoglobin increases within hours, but isn't specific to cardiac tissue
  • Troponin I rises in 3 hours, peaks at 14-18 hours, and remains elevated for 1-2 weeks
• Elevated WBCs usually indicate early inflammatory results in tissue necrosis
• EKG changes include ST elevation and Q waves
• Chest Radiograph notes heart size and configuration
• Radioisotope Studies (Thallium Scan) identifies infarcted or ischemic areas
• Echocardiogram assesses heart size, motion, and defects
• Positron Emission Tomography assesses metabolic activity and CABG suitability
• Multiple Gated Acquisition Scan (MUGA) assesses left ventricular function and impairment

Medical Management for Angina Pectoris

• Controlling symptoms by reducing cardiac ischemia by helping to promote rest and provision of oxygen is important
• Correcting modifiable cardiovascular risk factors is important
• Medication classes
  • Anti-platelet therapy prevents clot formation with aspirin as choice drug
  • Vasodilators (nitroglycerin) dilates coronary arteries
  • Beta-blockers slow heart rate and work load
  • Calcium channel blockers promote vasodilation

Medical Management for MI

• Supplemental oxygen is useful for high-risk patients
• Injury can be limited via reperfusion of the occluded artery
• Medications are similar to angina (ASA, Nitro, BB, CC)
  • Fibrinolytic agents (Streptokinase, tPA) are given within 3 hours; contraindicated with bleeding, aortic dissection, head trauma, hemorrhagic stroke, or surgery
• Coronary Artery Bypass Graft (CABG) uses the saphenous vein to bypass coronary occlusions to help treat chronic stable angina, significant left main CAD, and unstable angina
• Percutaneous Transluminal Coronary Angioplasty (PTCA) widens artery narrowing without open-heart surgery
  • Stent placement maintains vessel patency

Nursing Interventions

• Assess and manage pain, anxiety, and fatigue
• Instruct patient to avoid overexertion, stopping activity if chest pain, dyspnea, syncope, or vertigo occurs
• Encourage balanced activity with rest periods
• Educate patient on medications, triggers for angina, exercise benefits, smoking cessation, and medical follow-up
• Administer oxygen and prescribed nitroglycerin, monitor vitals, administer stool softeners
• Assess precipitating factors and pain along with monitoring vital signs and heart rhythm

Nursing Interventions for MI

• Focus on oxygen supply and demand with 2L/min O2 if pain, hypotension, dyspnea, or dysrhythmias occur
• Administer medications to decrease demand or increase supply with morphine, nitroglycerin, beta blockers, calcium channel blockers
• Instruct patients to rest and prevent complications with anti-embolic stockings
• Recommended daily intake is 2 G sodium, 1500 calories, low cholesterol and fluids

Cardiac Rehabilitation

• Cardiac rehabilitation helps patients after MI
• Components:
  • Exercise training teaches safe exercise to improve stamina
  • Education helps manage the condition and reduce future risks
• Cardiac rehabilitation may last 6 weeks-6 months for lasting effects