heart rhythm guide
heart rhythm guide

Heart Rhythm Conduction Defects

Right Bundle Branch Block


  • Heart Rate: Before each QRS, identical
  • P Wave: 120 to 200ms
  • PR Interval: Greater then 120ms
  • QRS Interval: Regular Sinus Rhythm (RSR) in V1
Right Bundle Branch Block




Left Bundle Branch Block


  • Heart Rate: Before each QRS, identical
  • P Wave: 120 to 200ms
  • PR Interval: Greater then 120ms
  • QRS Interval: Regular Sinus Rhythm (RSR) in V5
Left Bundle Branch Block




Preexcitation Syndrome


  • Heart Rate: Before each QRS, identical
  • P Wave: Less then 120ms
  • PR Interval: Greater then 100ms
  • QRS Interval: Delta wave distorts QRS
Preexcitation Syndrome




First Degree AV Block


  • Heart Rate: Before each QRS, identical
  • P Wave: 120 to 200ms
  • PR Interval: Greater then 200ms
  • QRS Interval: Regular Sinus Rhythm (RSR)
First Degree AV Block




Second Degree AV Block Mobitz I


  • Heart Rate: Conduction Intermittent
  • P Wave: Increasingly Prolonged
  • PR Interval: Less then 120ms
  • QRS Interval: QRS dropped in repeating pattern
Second Degree AV Block Mobitz I




Second Degree AV Block Mobitz II


  • Heart Rate: Conduction intermittent
  • P Wave: Interval is constant
  • PR Interval: Less then 120ms
  • QRS Interval: Fixed ratio of conduction P:QRS
Second Degree AV Block Mobitz II




Third Degree AV Block Complete


  • Heart Rate: Normal but not related to QRS
  • P Wave: None
  • PR Interval: None
  • QRS Interval: No relationship between P and QRS
Third Degree AV Block Complete




Next Section: Supraventricular Defects