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Clin Med - Cardio Exam #2 > ConductionBlocks > Flashcards

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

associated conditions of LBBB

- HTN
- CAD
- valve dz
- cardiomyopathies