Lecture 4: AV blocks Flashcards
Which EKG finding defines a first degree AV block?
PR interval >0.2 sec that is uniform
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/049/a_image_thumb.png?1541913834)
*0.2 sec = 5 small boxes or 1 large box
Presence of what 4 underlying conditions enhances the chances of a 1st degree AV block?
- Atherosclerosis
- HTN
- Diabetes
- Degeneration of conduction system/fibrosis CHD
What’s the cause of this rhythm?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/074/q_image_thumb.png?1541914319)
1st degree AV block
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/074/a_image_thumb.png?1541914344)
What’s the definition of a sinus rhythm?
Upright ‘P’ waves preceding QRS in lead II
Epigastric pain, GERD, and other upper GI sx’s can be a clue for that cardiac abnormality?
Inferior wall MI
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/097/a_image_thumb.png?1541915160)
What are the EKG characteristics of a 2nd degree AV block, Mobitz I (Wenckebach)?
i.e., intervals, QRS morphology…
- Narrow QRS
- Progressive PR-interval prolongation until ventricular beat is dropped, sequence is then repeated
- “Grouped beats”
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/128/a_image_thumb.png?1541915312)
The progressive lengthening of the PR-interval in Mobitz I (Wenckebach) results from what?
Level of the block is where?
- Earlier arrival in relative refractory period of A-V conduction
- Block is at level of AV node
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/141/a_image_thumb.png?1541915665)
List 4 etiologies which can lead to a 2nd degree AV block, Mobitz I (Wenckebach)?
- All things that cause 1st degree AV block
- Digitalis toxicity
- INFERIOR acute MI
- Myocarditis
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/153/a_image_thumb.png?1541916462)
Whenever you see “grouped beating” on an EKG strip you should immediately think what?
2nd degree AV block - Mobitz I (Wenckebach)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/165/a_image_thumb.png?1541916417)
A 2nd degree AV block, Mobitz Type II may be due to what 3 underlying etiologies?
- Ischemic heart disease
- May be seen with acute ANTERIOR MI
- Degeneration of conduction system (i.e., aging)
What type of acute MI is associated with a 2nd degree AV block, Mobitz Type I and Type 2?
- Type 1 (Wenckebach)= acuteINFERIORMI (sinceRCA supplies at or above AV node)
- Type 2 = acute ANTERIOR MI (since LAD supplies distal conduction system)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/179/a_image_thumb.png?1541917836)
What are the characteristic EKG findings of a 2nd degree AV block, Mobitz Type II?
Intervals, QRS…
- 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)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/194/a_image_thumb.png?1541917438)
A 2nd degree AV block, Mobitz Type II may occur at which 3 levels?
- Bundle of His
- Both bundle branches
- Fascicular branches
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/208/a_image_thumb.png?1541917565)
What is the progression and tx like for a 2nd degree AV block, Mobitz Type II?
- Progressive/irreversible
- Permanent pacemaker indicated
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/218/a_image_thumb.png?1541917670)
What is the ECG interpretation?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/227/q_image_thumb.png?1541918183)
2nd degree AV block, Mobitz Type II and LBBB
![](https://s3.amazonaws.com/brainscape-prod/system/cm/286/204/227/a_image_thumb.png?1541918224)