EKG Interpretation Lecture Notes

Introduction

• Presenter: Don
• Focus: Easiest way to interpret EKG for nursing students and new nurses.

Key Concepts

Conduction System of the Heart

• SA Node: Natural pacemaker found in the right atrium; initiates conduction.
• AV Node: Located between the right atrium and right ventricle; decides whether impulses from SA Node are passed on (gatekeeper).
• Bundle of His: Connects AV node to bundle branches.
• Bundle Branches: Left and right branches from the bundle of His extending towards the apex.
• Purkinje Fibers: Terminal fibers that spread impulses throughout the ventricles.

Heart Rate Generation

• SA Node: 60-100 beats per minute (bpm).
• AV Node: 40-60 bpm (if SA Node fails).
• Bundle of His and Purkinje Fibers: 20-40 bpm (if both SA and AV nodes fail).

EKG Components

• P Wave: Represents atrial depolarization (atria contracting).
• QRS Complex: Represents ventricular depolarization (ventricles contracting).
  • QRS visually resembles an inverted V (V for ventricles).
• T Wave: Represents ventricular repolarization (ventricles relaxing).

Atrial Repolarization

• Atrial repolarization occurs within the QRS complex and is not visible due to the stronger ventricular contraction.

EKG Segments and Intervals

• Focus on: PR Interval and QRS Complex.
• PR Interval: Distance from the start of P wave to the start of QRS; normal range is 0.12 to 0.20 seconds.
• QRS Complex Duration: Normal range is 0.06 to 0.12 seconds.

The Six-Step EKG Interpretation

1. Identify and Examine P Waves

   • Normal P waves are present and upright. Inversions/absences indicate dysrhythmias (e.g., junctional rhythm).

2. Measure PR Interval

   • Count small boxes between P wave and QRS; multiply by 0.04 seconds.
   • Magic number: 0.12 to 0.20 seconds.

3. Measure QRS Complex

   • Count small boxes in QRS; magic number is 0.06 to 0.12 seconds.

4. Identify Rhythm

   • Measure distance between R waves (R-R interval) to determine if rhythm is regular or irregular.
   • Tools: Calipers or index card for marking R waves.

5. Determine Heart Rate

   • Identify if EKG strip is a six-second strip (look for three lines).
   • Use Six Second Method: Count R waves in six seconds, multiply by 10 (best for irregular rhythms).
   • Use Big Box Method: 300 divided by the number of big boxes between R waves (best for regular rhythms).

6. Interpret the Strip

   • Analyze findings for diagnosis and understanding.

Conclusion

• Importance of verifying the EKG strip, especially for the six-second method.
• Encouragement to like and subscribe, and to suggest topics for future videos (e.g., dysrhythmias).
• Presenter: Don from Mint.