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
clues for 2nd degree Av block? type 1
reg p wabes
PR interval gets longer until a QRS is dropped
normal QRS but irregular
variable conduction bc not all p waves are conducted
group beating “pattern”
possible causes for 2nd degree AV block? type 1
ischemia, MI, inc vagal tone, AV node lesion, dig, calcium channel blockers, beta blockers
hemodynamic effects of 2nd degree AV block? type 1
usually asymptomatic but if brady can be symp (dec SV, CO, BP),
can deteriorate to higher degree block
treatments for 2nd degree AV block? type 1
usually none, continue to monitor
treat cause
atropine if symp
what is 2nd degree AV block - type II?
block occurs within the bundle of HIS (uncommon) or the bundle branches (common) often there is a complete block in one bundle (right bundle, resulting in wide QRS) and intermittent block in the other causing dropped QRS complexes. i
if the block is at the level of the HIS bundle for 2nd degree VA block type 2 is the QRS normal or wide? bundle branches?
hisbundle- normal
bundle branches- wide
PR interval for 2nd degree type 2 AV block?
may be normal or prolonged but it is will be constant or fixed.
what is the hallmark of he 2nd degree av block type 2?
constant PR interval
clues for 2nd degree type 2 AV block?
p waves are normal and will be followed by QRS except when blcoekd
blocked ps can vary 2:1 3:1 4:1
printerval remains constant or fixed
QRS may be normal (block in HIS bundle)
QRS may be wide (block in bundle branches)