13. AV Blocks

Question 1

What is a Type I 2° AV block? Nature of prob? ECG characteristics?

Answer 1

• Nature: progressive delay in AV conduction leads to a dropped P wave, then resets
• ECG:
  
  • Progressive delay in PR over ~3-4 beats (PR interval gets longer until P wave is dropped, then resets)
  • 2P:1QRS
  • Group beating QRSs

Question 2

What is a Type II 2° AV block? Nature of prob? ECG characteristics?

Answer 2

• Nature: AV conduction fails intermittently
• ECG:
  
  • Constant PR intervals
  • Intermittently dropped P waves
  • > (or equal to) 2P:QRS
  • Group beating QRSs

Question 3

What is a 3° AV block? Nature of prob? ECG characteristics?

Answer 3

• Nature: complete AV dissociation
• ECG:
  
  • Independent, but regular P-P and R-R rates (have diff rates)
  • Often > 2 P:QRS
  • QRSs regular, slow, and wide