Lecture on Myocardial Infarction (MI)

Introduction

• Speaker: Nurse Mike from SimpleNursing.com
• Topic: Heart attack, also known as Myocardial Infarction (MI)
• Access free quizzes and study guides available on SimpleNursing.com

Pathophysiology of MI

• Definition: Blockage in coronary arteries leading to heart muscle death due to lack of oxygen
• Necrosis: Occurs if blockage persists over 45 minutes

Causes of Arterial Narrowing

• Plaque Formation: Fatty deposits develop on artery walls
• Factors Contributing to Plaque:
  • Stress - Causes temporary narrowing (anxiety, cold, exercise, stimulants)
  • Smoking - Scars arteries
  • Obesity - BMI over 25
  • Diabetes and Hypertension - Damage coronary arteries
  • Diet High in Cholesterol - Animal fats contribute to fatty buildup
• Atherosclerosis: Hardening of arteries due to plaque

Risk Factors

• More common in African-American males
• Increased risk with age over 50, more common in men

Pathogenesis

• Plaque Rupture: Leads to blood clot formation
• Lack of Oxygen: Heart cells die within minutes, releasing proteins called troponin
• Troponin: Key indicator of MI

Types of Ischemic Heart Disease

1. Coronary Artery Disease (CAD) - Small
2. Stable Angina - Medium
3. Acute Coronary Syndrome (ACS) - Large
   • Unstable Angina
   • Myocardial Infarction (MI)

Symptoms of MI

• Chest Pain: Left substernal pain, crushing, heavy pressure
• Radiating Pain: Jaw, left arm, mid-back, shoulder
• Other Signs: SOB, nausea, vomiting, diaphoresis, anxiety
• Silent MI: Common in diabetics and women

Diagnostics

• EKG First: St elevation or depression
• Troponin Labs: Confirms MI (Troponin > 0.5)
• Other Labs: CK, CKMB, CRP (less important)

Treatment

1. Immediate:
   • Oxygen, Aspirin, Nitro, Morphine
   • Goal: Unclog artery within 45 minutes
2. Surgical Interventions:
   • Angioplasty (PCI) or Bypass (CABG)
   • Thrombolytics if no surgery available
3. Stress Test: To diagnose narrowing
   • Exercise or Nuclear Stress Tests

Drug Therapy

• Mona Protocol:
  • Oxygen, Aspirin, Nitro, Morphine
• Nitroglycerin: Avoid with Viagra, sublingual, headache, hypotension
• Morphine: Chest pain after morphine indicates MI

Complications and Management

• Cardiogenic Shock: Low BP, agitation, confusion, cool skin
• V-fib and V-tach: Defibrillation required
• Heart Failure: Fluid overload, push IV diuretics
• Pericarditis: Monitor Beck's Triad
• Mitral Valve Prolapse: Heart murmur, a-fib risk

Post-MI Education

• Lifestyle Changes:
  • Low sodium, low fluid intake, exercise
  • Smoking cessation
• Diet: Avoid high sodium, animal fats
• Medications: Anti-platelets, Statins (avoid with liver issues, avoid grapefruit juice)

Conclusion

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