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Identifying Type I Second-Degree AV Block

This rhythm strip illustrates type I second-degree AV block. Look for these distinguishing characteristics:

  • Rhythm: Atrial—regular; ventricular—irregular
  • Rate: Atrial—80 beats/min; ventricular—50 beats/min
  • P wave: Normal
  • PR interval: Progressively prolonged
  • QRS complex: 0.08 second
  • T wave: Inverted
  • QT interval: 0.46 second
  • Other: Wenckebach pattern of grouped beats; PR interval appearing progressively longer until QRS complex drops