Heart Block Flashcards
What is heart block?
HB = bradyarrhythmia caused by delay / interruption in electrical conduction between Atria + Ventricles
What are the Cardiac causes of HB? (5 things)
- Post MI
- AV block
- SA node dysf
- Inf End
- Fibrosis w age
What are the Non-Cardiac causes of HB? (4 things)
- Vasovagal
- Hypothermia
- Hypothyroidism
- Raised ICP (bc HTN)
What are the Meds causes of HB? (4 things)
- Amiodarone
- Beta blockers
- Calcium Ch blockers
- Digoxin
(All HF meds)
How can a MI cause Heart Block?
AV node supplied by RCA
What is 1st Degree HB in simple terms?
Delayed conduction thru AV node
What is 2nd Degree HB in simple terms?
Progressive delayed conduction / intermittently blocked conduction
What is 3rd Degree HB in simple terms?
TOTAL interruption of conduction between Atria + Ventricles –> complete AV dissociation
What is seen on an ECG for 1st Degree HB?
CONSTANT PR prolongation (200+ ms)
What more srs conditions can 1st Degree HB be a sign of? (3 things)
- Inf End
- BBB
- Aortic Root Abscess
What are the 2 types of 2nd Degree HB?
- Mobitz Type 1 (Wenckebach)
- Mobitz Type 2
What is seen on an ECG of Mobitz Type 1 (Wenckebach)? (4 steps)
- Progressive lengthening of PR interval
- Followed by dropped beat (Wencke Wencke Wencke BACH)
- Followed by a normal conducted beat w shorter PR interval
- Cycle continues
What is seen on an ECG of Mobitz Type 2? (2 things)
- Constant PR interval
- Occasional missing QRS complex after P wave (naked P wave lol)
Why are there occasional missing QRS complexes after P waves in Mobitz Type 2?
Occasionally atrial conduction NOT transmitted to ventricles
What is a Fixed Ratio Block in Mobitz Type 2?
Fixed number of P waves each time before you get a QRS complex