Lecture 4: AV blocks Flashcards

1
Q

Which EKG finding defines a first degree AV block?

A

PR interval >0.2 sec that is uniform

*0.2 sec = 5 small boxes or 1 large box

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Presence of what 4 underlying conditions enhances the chances of a 1st degree AV block?

A
  • Atherosclerosis
  • HTN
  • Diabetes
  • Degeneration of conduction system/fibrosis CHD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What’s the cause of this rhythm?

A

1st degree AV block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What’s the definition of a sinus rhythm?

A

Upright ‘P’ waves preceding QRS in lead II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Epigastric pain, GERD, and other upper GI sx’s can be a clue for that cardiac abnormality?

A

Inferior wall MI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the EKG characteristics of a 2nd degree AV block, Mobitz I (Wenckebach)?

i.e., intervals, QRS morphology…

A
  • Narrow QRS
  • Progressive PR-interval prolongation until ventricular beat is dropped, sequence is then repeated
  • “Grouped beats”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The progressive lengthening of the PR-interval in Mobitz I (Wenckebach) results from what?

Level of the block is where?

A
  • Earlier arrival in relative refractory period of A-V conduction
  • Block is at level of AV node
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

List 4 etiologies which can lead to a 2nd degree AV block, Mobitz I (Wenckebach)?

A
  • All things that cause 1st degree AV block
  • Digitalis toxicity
  • INFERIOR acute MI
  • Myocarditis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Whenever you see “grouped beating” on an EKG strip you should immediately think what?

A

2nd degree AV block - Mobitz I (Wenckebach)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

A 2nd degree AV block, Mobitz Type II may be due to what 3 underlying etiologies?

A
  • Ischemic heart disease
  • May be seen with acute ANTERIOR MI
  • Degeneration of conduction system (i.e., aging)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What type of acute MI is associated with a 2nd degree AV block, Mobitz Type I and Type 2?

A
  • Type 1 (Wenckebach)= acuteINFERIORMI (sinceRCA supplies at or above AV node)
  • Type 2 = acute ANTERIOR MI (since LAD supplies distal conduction system)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the characteristic EKG findings of a 2nd degree AV block, Mobitz Type II?

Intervals, QRS…

A
  • Fixed/uniform PR interval
  • Occasional dropped beats (QRS) in 2:1, 3:1, or 4:1 pattern
  • QRS usually wide (due to block being distal)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

A 2nd degree AV block, Mobitz Type II may occur at which 3 levels?

A
  • Bundle of His
  • Both bundle branches
  • Fascicular branches
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the progression and tx like for a 2nd degree AV block, Mobitz Type II?

A
  • Progressive/irreversible
  • Permanent pacemaker indicated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the ECG interpretation?

A

2nd degree AV block, Mobitz Type II and LBBB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the EKG findings associated with a third degree heart block (aka complete block)?

A
  • P waves NEVER related to QRS complexes
  • 2 indpendent rhythms (A-V dissociation)
17
Q

A 3rd degree heart block can occur above or below the AV node and what serves as the escape rhythm for each type and QRS findings?

Ventricular rate?

A
  • Above –> junctional rhythm/ w/ NARROW QRS (rate 40-55)
  • Below –> ventricular pacemaker w/ WIDE QRS (rate 20-40)
18
Q

What are 3 of the major etiologies associated with 3rd degree heart block (aka complete AV block)?

A
  • Ischemic
  • Infiltrative diseases
  • Cardiac surgery: by-pass/valve replacement, myocarditis, degenerative
19
Q

How do you treat a 3rd degree AV block?

A

Permanent pacemaker

20
Q

How do you interpret this rhythm and how do you treat?

A
  • 1st degree AV block
  • Tx: do nothing
21
Q

When looking at a strip showing a 2:1 AV block which can be caused by either a Mobitz type I or II, what general rule of thumb should be used to distinguish the cause?

A
  • If PR interval is prolonged and QRS is narrow it is likely a type I (Wenckebach)
  • If PR interval is normal and QRS is wide it is likely a type II, and pacemaker is warranted
22
Q

Which technique can be employed at the bedside to get a better look at the root cause of a 2:1 AV block?

A

Vagal maneuver

23
Q

How would you interpret this EKG finding?

A

3rd degree AV block

24
Q

Interpret this EKG

A

LBBB w/ 2nd degree AV block, type II