When interpreting rhythms, always do these three things:
1. Find out what the atrium is doing
2. Find out what the ventricle is doing
3. Figure out the relationship between the atrium and ventricle (PR-interval)
The answer usually lies in the PR-interval !
- 1st Degree AV Block = “delay” > 200ms at AV node or His bundle.
When the P:QRS>1, consider 2nd and 3rd degree AV Blocks
- 2nd Degree AV Block = Not every atrial impulse goes through to the ventrcles. (ie P:QRS >1)
Mobitz Type I (Wenckebach) -Each atrial impulse has longer and longer delay until it fails to conduct to the ventricle. Progressive PR-interval lengthening before a non condected beat
Mobitz Type II - typically due to block below AV node in His bundle. Some but not all impulses are transmitted to the ventricles WITHOUT progressive PR lengthening