AV Blocks

Question 1

what is an atrioventricular conduction block?

Answer 1

a disruption in the electrical pathway between atria and ventricles, leading to varying degrees of heart block

Question 2

what are the types of AV blocks?

Answer 2

1st degree
2nd degree (Mobitz I/Wenckebach, Mobitz II)
3rd degree (complete block)

Question 3

where can AV blocks occur within the heart?

Answer 3

supranodal
infranodal

Question 4

supranodal location of AV block and associated signs?

Answer 4

above bundle of His
associated with narrow QRS complex
less symptomatic

Question 5

infranodal location of AV block and associated signs?

Answer 5

below bundle of His
associated with wide QRS complex
increased risk for progression to complete block

Question 6

what location of AV block is above the bundle of His, associated with narrow QRS complex and typically results in less symptoms?

Answer 6

supranodal AV block

Question 7

what location of AV block is below the bundle of His, associated with wide QRS complexes and increased risk for progression to complete heart block?

Answer 7

infranodal AV block

Question 8

1st degree AV block

Answer 8

delay in conduction through AV node
pronged PR interval (> 0.2 s) w/o dropped beats (QRS complexes)

Question 9

1st degree AV block ECG findings?

Answer 9

prolonged PR interval (>0.2 s)
each P wave followed by QRS complex
regular rhythm

Question 10

1st degree AV block clinical significance?

Answer 10

typically asymptomatic/no change in cardiac function
typically does not progress to higher degree blocks
rarely requires tx

Question 11

why might PR intervals progressively become longer in the case of 1st degree heart block?

Answer 11

medications that suppress AV conduction

Question 12

what degree AV block results from a delay in conduction of the AV node an prolonged PR intervals (> 0.2 s) w/o dropped beats?

Answer 12

1st

Question 13

what degree AV block ECG findings are typically as followed:
prolonged PR interval (> 0.2 s)
each P wave followed by QRS complex
reg rhythm

Answer 13

1st

Question 14

2nd degee AV block (Mobitz I/Wenckebach, Mobitz II)

Answer 14

AV conduction disturbance in which impulses between atria and ventricles intermittently fail

Question 15

2nd degree AV block- Mobitz I/Wenckebach

Answer 15

progressive lengthening of the PR interval until one impulse is not conducted and a beat (QRS complex) is dropped

Question 16

what degree AV block results in progressive lengthening of the PR interval until one impulse is not conducted and a beat (QRS complex) is dropped?

Answer 16

2nd degree- type I/Mobitz I

Question 17

2nd degree AV block Mobitz I/Wenckebach ECG findings

Answer 17

progressive lengthening of the PR interval until a beat (QRS complex is dropped) after a certain number of P waves
irregular rhythm
narrow QRS complex

Question 18

2nd degree AV block Mobitz I/Wenckebach clinical significance?

Answer 18

often asymptomatic
typically does not progress to higher degree heart block
rarely requires tx

Question 19

what degree AV blocks are often asymptomatic, typically do not progress to higher degree heart block and rarely require treatment?

Answer 19

1st degree
2nd degree-Mobitz I/Wenckebach

Question 20

2nd degree AV block-Mobitz II

Answer 20

consistent PR intervals with intermittent dropped beats (QRS complex)
non-conduction of one or more impulses

Question 21

2nd degree AV block-Mobitz II ECG findings

Answer 21

consecutive PR intervals are the same and normal followed by nonconduction of one or more impulses (P wave)- occurs in fixed interval (2:1, 3:1 etc)
QRS complex can be narrow or wide depending on location of block
irregular rhythm

Question 22

2nd degree AV block-Mobitz II clinical significance?

Answer 22

more serious condition that has higher risk for progression to complete block
may require a pace maker
dizziness
syncope

Question 23

what degree AV block results in consistent PR intervals with intermittent dropped beats (QRS) due to nonconduction of one or more impulses (P waves) occurring in a fixed ratio

Answer 23

2nd degree AV block-Mobitz II

Question 24

what degree AV block is a more serious condition with higher risk for progression to complete block, may require a pacemaker and may result in dizziness and syncope?

Answer 24

2nd degree AV block-Mobitz II

Question 25

what happens if HR is slow in combination with the presence of a 2nd degree AV block-Mobitz II?

Answer 25

cardiac output will decrease with the blocked impulse

Question 26

3rd degree AV block-complete block

Answer 26

all impulses are blocked at the AV node and none are transmitted to the ventricles complete dissociation between P waves and QRS complexes/ between atrial and ventricular activity no impulses conducted

Question 27

what degree AV block results in no impulse conduction as all impulses are blocked at the AV node, with none transmitted to the ventricles as well as complete dissociation between P waves and QRS complexes/atrial ventricular activity?

Answer 27

3rd

Question 28

3rd degree AV block- complete block ECG findings

Answer 28

P waves and QRS complexes are independent of one another/have no relationship atrial rate faster than ventricular rate wide QRS complex if there is ventricular involvement

Question 29

3rd degree AV block- complete block clinical significance?

Answer 29

medical emergency requires immediate medical intervention may require pacemaker bradycardia hypotension syncope

Question 30

what degree AV block is considered a medical emergency requiring immediate intervention and potentially a pacemaker and is often accompanied by bradycardia, hypotension and syncope?

Answer 30

3rd degree-complete