AV blocks Flashcards
what are AV blocks?
delays (prolongation) or interruptions in electrical conduction from the atria to the ventricles
what are the causes of AV blocks/
ischemia, MI, inc vagal tone (MI), lesions that occur w inc age (fibrosis and calcium) and dig tox
blocks within the bundle branches are reversible and not progressive? T or F
F they are progressive and irreversible
whats the diff between blocks in the bundle branches and AV node or HIS bundle in re: how they look o ECG?
QRS wide in bundle branches and normal in AV node and HIS bundle
are blocks in the AV node or HIS bundle reversible and not progressive?
yes they are reversible
AV node is the usual site for what kind of block?
first-degree AV block and type 1 second degree block
Bundle branches are the usual site for what ind of block?
type 2 second degree block
complete AV block occurs where?
at any level but is most common in the bundle of HIS and bundle branches
what is a first degree AV block?
occurs when there is prolongation of conduction in the AV node.
clues on ECG for first degree AV block?
reg p waves
PR interval >.20 and is usually constant but may vary
QRS is usually normal width
reg QRS
is each sinus beat conducted to the ventricles? (first degree AV block)
yes although delayed, it is still 1:1 conduction
possibly causes for first degree AV block?
ischemia, MI (inferior), inc vagal tone, AV node lesion, digoxin
what are some hemodynamic effects of first degree AV block?
usually asymptomatic but if brady can be symp (dec SV, CO, BP),
can deteriorate to higher degree block
treatment for first degree AV block?
usually none treat underlying cause
atropine if symp
what is second degree AV block? - type 1 (wenckebach)
occurs almost always at the AV node level and is usually transient. progressive prolongation of conduction (P-R interval gradually lengthens eg. .24-.30 -.32) delays in conduction progress until an impulse is completed blocked (no QRS following a P wave)
usaually one QRS is blocked and the pattern repeats itself, resulting in “group” beating