Flashcards in AV Blocks And Hemiblocks (Johnston) Deck (15):
What are some etiologies of 1st degree AV block?
This type of AV block has a progressive PR interval prolongation prior to dropped QRS and has "grouped beats". Progressive lengthening results from earlier arrival in relative refractory period of AV conduction and implies impairment of AV conduction. It is transient.
Secondary AV block-Wenckebach (Type I mobitz)
What are etiologies of Wenckebach secondary AV blocks?
All those that cause primary AV block
ISCHEMIC EVENTS (MI-INFERIOR)
This type of AV block may be seen with an inferior AMI, the level of block is at the level of the AV node, and has a narrow QRS complex
2nd degree AV block-Wenckebach (Mobitz I)
What are etiologies of 2nd degree AV block-Mobitz type II?
Ischemic heart disease
May be seen with acute ANTERIOR MI
Degeneration of conduction system
This type of AV block has a uniform PR interval, a dropped beat (QRS) and the block occurs at the level of Bundle of his, both bundle branches, and fascicular branches. It is progressive/irreversible
These may be seen with ANTERIOR AMI because block is distal to AV node; worse prognosis
2nd degree AV block, Mobitz type II
In this type of AV block, the P waves are never related to QRS complexes
Third degree AV block (complete heart block)
Describe the QRS and ventricular rate in 3rd degree heart block at the junctional focus:
Ventricular rate 40-60/min
Describe the QRS and ventricular rate in 3rd degree AV block at the ventricular focus:
Wide QRS (PVC-like QRS's)
Ventricular rate: 20-40/min
What are some etiologies of third degree AV block?
Cardiac surgery --> BY-PASS, valve replacement, myocarditis, degenerative
How do you treat a 3rd degree AV block?
Describe the PR interval in 1st degree AV block:
Describe the PR interval in Wenckebach (2nd degree type 1)
In which AV blocks do you have P waves without a QRS response?
Wenckebach and Mobitz type 2
3rd degree AV block