Flashcards in ConductionBlocks Deck (33)
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1
define conduction block
delay or disruption in transmission of an impulse from atria to ventricle
2
What are the types of AV conduction blocks and describe them?
- 1st degree: AV synchrony is maintained (every p goes with a QRS)
- 2nd degree: intermittent loss of AV conduction (not every p has a QRS)
- 3rd degree: complete AV dissociation
3
etiology of AV conduction blocks
- MC = progressive heart conduction disease
- incr. vagal tone
- ischemic heart dz
- infiltrative process (amyloid/sarcoid)
- myocarditis
- congenitl heart dz
- familial dz
- malignancies
- drugs
- heart surgery
4
define 1st degree AV conduction block
- prolonged PR interval (greater than 0.2s)
- every p goes with every QRS
- not likly to progress to 2nd degree
5
etiology of 1st degree AV conduction block
- structural abnormalities
- increased vagal tone
- drugs that impair/slow AV conduction
6
epidemiology of 1st degree AV conduction block
increased in trained athletes
7
clinical presentation of 1st degree AV conduction block
ususally asx
8
management of 1st degree AV conduction block
- if PRI under 300ms ==> no intervention
- if wide QRS ==> refer
- tx underlying cause
- avoid AV nodal blocking meds
9
define 2nd degree AV conduction block (generally speaking)
- not every QRS has a p
- two types
10
epidemiology of 2nd degree AV conduction block
increased in trained athletes
11
etiology of 2nd degree AV conduction block
- heart drugs
- lithium
- inflammatory dz
- infiltrative dz
- malignancies
- collagen vascular dz
12
diagnostics for 2nd degree AV conduction block
- EKG
- electrolytes
- digoxin
- biomarkers
- Lyme titers
- echo
13
define type I 2nd degree AV conduction block
- progressive slowing of subsequent AV node impulses until node fails to conduct
- cycle repeats
- Wenchback Walk
14
clinical presentation of type I 2nd degree AV conduction block
- asx
- decr CO = fatigue, lightheadedness, syncope, angina, heart failure
15
treatment of type I 2nd degree AV conduction block
- tx underlying cause
- no specific tx when asx
- monitor EKG
- refer when sxatic
16
define type II 2nd degree AV conduction block
- PR interval remains equal until dropped beat
- no change in PR interval
- frequently progresses to 3rd degree
17
clinical presentation of type II 2nd degree AV conduction block
- ranges from asx to many
- if decr HR or many dropped beats = decr. CO ==> fatigue, lightheadedness, syncope
18
treatment of type II 2nd degree AV conduction block
- tx underlying cause
- avoid AV blocking drugs
- pacemaker
19
define 3rd degree AV conduction block
- complete failure of AV node to conduct any impulse from atria to ventricles
- variable PR interval
- with escape rhythm
20
possible sites of 3rd degree AV conduction block
- AV node = narrow QRS
- Bundle of His = narrow QRS
- Proximal (B) Bundle Branches = wide QRS
- R bundle w/ L fasicles = wide QRS
21
clinical presentation of 3rd degree AV conduction block
- more distal block = decr. rate
- distal blocks = syncope
- chest pain (in MI)
- lightheadedness
- DOE
- bradycardia
- vtach/fib/ventricular brady
- asystole
22
diagnostics for 3rd degree AV conduction block
same as 2nd degree
- EKG
- electrolytes
- digoxin
- cardiac biomarkers
- Lyme titers
- echo
-*CBC & blood cx to r/o endocarditis*
23
treatment of 3rd degree AV conduction block
- temporary then pacemaker
- refer
- treat underlying cause
- avoid rx that block AV node
24
define LBBB
- wide QRS (greater than 0.12s)
- broad R waves in V1-6 & broad S waves in AVR
25
LBBB is difficult to ddx with _____ d/t _____.
- myocardial ischemia & infarction
- ST-T abnormalities
26
New LBBB is _____ until proven otherwise.
MI
27
diagnostics for LBBB
- echo
- stress testing (CAD)
28
treatment for LBBB
- if young + asx w/o CAD ==> no tx
- tx underlying condition
- reduce risks
- consider pacemaker
29
clinical presentation of RBBB
asx
30
