EKG Interpretation Lecture Notes

Introduction

• Speaker: Nicole Weaver, nurse with 10 years experience in ICU and emergency departments.
• Objective: Teach how to interpret EKGs by identifying normal rhythms and common abnormalities.
• Focus: Recognize rhythms that are too fast, too slow, or deadly.

EKG Basics

• EKG Graph Paper:
  • Dark lines and lighter lines create large boxes and small boxes.
  • Vertical Axis (Amplitude):
    • 1 small box = 1 millivolt.
  • Horizontal Axis (Time):
    • 1 small box = 0.04 seconds.
    • 5 small boxes (1 large box) = 0.20 seconds.
    • 5 large boxes = 1 second.

Electrical Activity of the Heart

• SA Node: Located in the right atrium, starts electrical activity, beats 60-100 bpm.
• Pathway:
  • Signal from SA node ➔ Atria ➔ AV Node (pause) ➔ Bundle of His ➔ Bundle branches ➔ Purkinje fibers ➔ Ventricles.
• Depolarization: Electrical stimulus causes contraction.
• Repolarization: Relaxation phase.

EKG Waveforms

• P Wave:
  • Small positive deflection.
  • Represents atrial depolarization (atrial contraction).
• QRS Complex:
  • Represents ventricular depolarization (ventricular contraction).
  • Larger due to more electricity in ventricles.
• T Wave:
  • Represents ventricular repolarization (ventricular relaxation).
  • Atrial repolarization not visible.

Important Intervals

• PR Interval:
  • From start of P wave to start of QRS complex.
  • Indicates time for SA node signal to reach and be processed by the AV node.
  • Should be < 0.20 seconds (5 small boxes).
• QRS Interval:
  • From start of Q to end of S.
  • Should be < 0.12 seconds (3 small boxes) for efficient ventricular contraction.
• QT Interval:
  • From start of Q to end of T.
  • Indicates full cycle of ventricular contraction and relaxation.
  • Should not be prolonged to avoid inefficiency.

Important Segments

• ST Segment:
  • Line between S wave and T wave.
  • Should be at baseline (isoelectric line).
  • ST elevation (>2 small boxes) can indicate infarction or ischemia.
• PR Segment:
  • Pause between SA and AV node.
  • Not usually the focus.

Normal Sinus Rhythm

• Should see a P, QRS, and T sequence for each heartbeat.
• Any deviation from this order indicates a problem.

Conclusion

• Goal: Recognize EKG patterns quickly to provide effective patient care.
• Encouragement to continue learning and growing in skills.
• "Happy nursing!"