Understanding Cardiovascular Diagnostic Tests

Oct 13, 2024

Lecture Notes: Diagnostic Tests in Cardiovascular System

Introduction

  • Presented by Cathy from Level Up RN
  • Focus on diagnostic tests related to the cardiovascular system
  • Includes a quiz at the end to test knowledge
  • Reference: Medical Surgical Nursing Second Edition Flashcard Deck and Lab Values Deck

Cardiac Enzymes

  • Released in response to heart ischemia (e.g., myocardial infarction)
  • Four key labs: CKMB, myoglobin, troponin T, and troponin I

CKMB

  • Enzyme in cardiac muscle
  • Normal: 0%
  • Elevated 3-6 hours post-heart damage, stays elevated for 2-3 days

Myoglobin

  • Protein found in heart and skeletal muscle
  • Normal: under 90
  • Elevated 2-3 hours after damage, remains for 24 hours
  • Not specific to heart

Troponin T and I

  • Found in heart muscle fibers
  • Most specific for diagnosing myocardial infarction
  • Normal Troponin T: under 0.1
  • Normal Troponin I: under 0.03
  • Elevated 2-3 hours post-damage
  • Troponin T elevated for 2 weeks (T for Two weeks)
  • Troponin I elevated for 1 week (I for One week)

Cholesterol

  • Total cholesterol should be <200

LDL (Low-Density Lipoprotein)

  • "Bad" cholesterol
  • Normal: <130
  • High-risk patients should have LDL <100

HDL (High-Density Lipoprotein)

  • "Good" cholesterol
  • Normal: >55 for females, >45 for males

Triglycerides

  • Normal: 35-135 for females, 40-160 for males

Blood Pressure

  • Expected: Systolic <120, Diastolic <80

Hypertension Ranges

  • Varies across sources
  • Check with textbooks/professors for specific ranges

Other Lab Values

  • Ranges may vary slightly across sources
  • Focus on clearly out-of-range values for exams

Red Blood Cells

  • Females: 4.2-5.4
  • Males: 4.7-6.1

Platelets

  • Normal: 150,000-400,000

Hemoglobin

  • Females: 12-16
  • Males: 14-18

Hematocrit

  • Females: 37%-47%
  • Males: 42%-52%
  • Hematocrit is approx. 3x hemoglobin

APTT (Activated Partial Thromboplastin Time)

  • Normal: 30-40 seconds
  • Extended when on heparin: 45-80 seconds

PT (Prothrombin Time) and INR

  • PT normal: 11-13 seconds
  • On warfarin: PT 17-26 seconds
  • INR: normal ~1, on warfarin 2-3

D-dimer

  • Normal: under 0.4
  • Elevated with clots (e.g., DVT, PE)

HBNP

  • Released by heart ventricles due to fluid overload
  • Normal: under 100
  • Elevation indicates heart failure

Quiz Questions

  1. Most specific cardiac enzyme for ischemia? Troponin
  2. Normal range for platelets? 150,000-400,000
  3. What lab is elevated in presence of a clot? D-dimer

Conclusion

  • More diagnostic tests will be covered in future videos
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