Issues With The AV Node - Heart Blocks Flashcards
Impulse begins in SA node but is delayed on way to AV node OR AV conduction time is prolonged Prolonged PRI (time from SA to AV) Possible slow HR bc impulse takes a long time for ventricular contraction to occur
1st degree heart block
1st degree heart block
Impulse begins in SA node but is delayed on way to AV node OR AV conduction time is prolonged
Prolonged PRI (time from SA to AV)
Regular R-R
Possible slow HR
Why can a 1st degree heart block have a possible slow HR?
Bc the impulse takes a long time for ventricular contraction to occur
What are possible causes for a 1st degree heart block?
CAD
MI
BBs (can slow impulse too much)
Can a 1st degree heart block be asymptomatic?
Yes unless there is significant bradycardia - it can progress to a worsening block
Main telemetry of 1st degree heart block?
Increased PRI
A 2nd degree AV block, Type I is also known as…
Wenkebach or Mobitz I heart block
Progressive prolongation of PRI until one impulse doesn’t get through
P wave before every QRS until a P wave stands alone (conduction blocked ==> no QRS)
R-R interval irregular (bc of dropped QRS)
2nd degree AV block, Type I (Wenkebach or Mobitz I heart block)
2nd degree AV block, Type I (Wenkebach or Mobitz heart block)
Progressive increase in PRI until an impulse is dropped and there is no QRS
R-R interval irregular (bc of dropped QRS)
2nd degree AV block, Type I (Wenkebach or Mobitz I heart block) possible causes…
RCA disease/infarction
BBs
Does a 2nd degree AV block Type I (Wenkebach or Mobitz I heart block) usually progress?
No - usually asymptomatic and rarely progresses - need to monitor it ==> QRS dropping can cause CO sx if occur frequently enough
2nd degree AV block, Type II (Mobitz II)
No change in PRI
Blocked conduction of ONE IMPULSE to ventricles
R-R interval varies (bc QRS drones)
P:QRS > 1:1
No change in PRI
Blocked conduction of ONE IMPULSE to ventricles
R-R interval varies (bc QRS drops)
P:QRS > 1:1
2nd degree AV block, Type II (Mobitz II)
Telemetry characteristics of 2nd degree AV block, Type II (Mobitz II)…
PRI stays the same
The dropped QRS does not always occur every other
2nd degree AV block, Type II (Mobitz II) possible causes…
MI (LAD) AV node infarction (RCA) Digoxin toxicity Drop in CO if dropped QRS happen more frequently/min that's Type I (bc lose ventricular complex c dropped QRS) Pacemaker Atropine
Which type of heart block can progress to a complete heart block, an emergent situation?
2nd degree AV block, Type II (Mobitz II)
A 3rd degree AV block is AKA…
Complete heart block
Complete heart block
No impulses from above the ventricles are conducted through the AV node
No communication between A/Vs
2 syncythiums act independently
Regular P waves
P waves have no relation to QRS, but QRS is regular
R-R interval regular
WIDE QRS (bc impulse to Vs coming from BELOW AV node)
HR 30-50bpm
3rd degree heart block
3rd degree heart block HR…
30-50bpm
3rd degree heart block
Complete heart block
No impulses from above ventricles conducted through AV node
No communication between A/Vs
2 syncythiums act independently
Regular P waves
P waves have no relation to QRS, but QRS regular
R-R interval regular
WIDE QRS (bc impulse to Vs coming from BELOW AV node)
What is a characteristic of a 3rd degree heart block?
The atria and ventricles contract @ their own paces and don’t communicate - they are not in sync (act independently of e/o)
3rd degree heart block telemetry characteristics…
AV valves closing during systole when atria contract, so there is a decrease in atrial kick and a decrease in CO bc of decreased ventricular filling ==> P waves not related to QRS
No PRI
N/A QRS duration calculation
3rd degree heart block possible causes…
MI Digoxin toxicity Drop in CO (dizziness, SOB, angina, diaphoresis) Permanent pacemaker Atropine
COMPLETE HEART BLOCK =
MEDICAL EMERGENCY
