Bradycardia and Bradyarrhythmias

Bradycardia and Bradyarrhythmias

David Ray Velez, MD

Table of Contents

Classification
EKG Patterns

See Also:

*See Sinus Bradycardia
*See First Degree AV Block
*See Second Degree AV Block, Mobitz Type I (Wenkebach)
*See Second Degree AV Block, Mobitz Type II
*See Third Degree AV Block (Complete Heart Block)

Classification

Bradycardia: Heart Rate < 60 Beats per Minute

Narrow Complex Bradycardia

  • Regular Rhythm
    • Sinus Bradycardia
    • Third Degree (Complete) AV Block – with Junctional Escape
  • Irregular Rhythm
    • Atrial Fibrillation with Slowed Ventricular Response
    • Second Degree AV Block, Type I (Wenkebach)
    • Second Degree AV Block, Type II

Wide Complex Bradycardia

  • Regular Rhythm
    • Third Degree (Complete) AV Block – with Ventricular Escape
  • Irregular Rhythm
    • Second Degree AV Block, Type I (Wenkebach)
    • Second Degree AV Block, Type II

EKG Patterns

Sinus Bradycardia

  • HR < 50-60 bpm
  • Normal P Waves

Sinus Bradycardia

First Degree AV Block

  • Prolonged PR Interval > 200 ms
  • No Interruption in AV Conduction

First Degree AV Block

Second Degree AV Block, Mobitz Type I (Wenkebach)

  • Progressive PR Interval Prolongation Followed by Dropped Beats
  • The Largest Absolute PR Interval Increase is Most Often Between the First and Second Beats of the Cycle
  • The P-P Interval Remains Relatively Constant Throughout the Cycle
  • The R-R Interval Progressively Decreases Throughout the Cycle
  • Often Cycles in a Repeated P:QRS Ratio (3:2, etc.)

Second Degree AV Block, Mobitz Type I (Wenkebach)

Second Degree AV Block, Mobitz Type II

  • Normal PR Interval (120-200 ms)
  • Sudden Dropped Beats
  • P Waves “March” Through at a Constant Rate

Second Degree AV Block, Mobitz Type II

Third Degree AV Block (Complete Heart Block)

  • P Wave and QRS Complex are Completely Independent
  • The P-P Interval Remains Relatively Constant

Third Degree AV Block