EKG Blocks

Question 1

Sinus Block

Answer 1

The SA Node fails to produce an impulse so the EKG fails to show a P wave:QRS (should be 1:1)
The timing returns after the missed cycle.

Question 2

AV block

Answer 2

AV blocks slow or eliminate the conduction from the atria to the ventricles
1st degree: Lengthens the delay between atrial and ventricular depolarization
2nd degree: Some get through , some don’t
3rd degree: Completely blocks atrial to ventricles

Question 3

1st degree AV block shows on EKG …

Answer 3

regular length of PR interval - just long

longer than 0.2 seconds

Question 4

2nd degree AV block shows on EKG …two types

Answer 4

AV node: wenkelbach and bundle of his : mobitz

Think of old man wenkelbach carrying boxes and “millenial” mobitz texting and randomly things

Question 5

Wenkelbach 2nd degree AV block

Answer 5

1. if block in AV node (Wenkelbach) - progressive lengthening of PR interval till QRS drops. consistenting dropped so short, longer, longerrrr drop, short, longer, longerrr, drop …) Always will be one less QRS than P for the ratio

Question 6

Mobitz 2nd degree AV block

Answer 6

2. if block in conduction system (really in bundle of His not AV) (Mobitz): PR interval normal, just drops one QRS every so often

Question 7

3rd degree AV node block

Answer 7

Complete block of pacing by the SA node: highest automaticity foci below the block will be the pacer.

• If block is in the top of the AV node the Junctional foci (between AV and bundle of his) will pace at its inherent rate
• If total AV node block it will be a ventricular foci that will pace.

SA node is still pacing with so P Waves will still be present they will just NOT pass through to the ventricle.
AV Disassociation Ps and QRS independent of each other.

Question 8

paced above the ventricles will have narrow or wide QRS complex? paced from ventricles will have narrow or wide QRS complex?

Answer 8

above ventricles: narrow, ventricle: wide

Question 9

bundle branch blocks (aka ventricle blocks)

Answer 9

delays conduction to whichever ventricle it supplies, QRS is a combo of the two ventricles depolarizing - two R waves: R and R’
- widened QRS

Question 10

what leads do you look at for BBB?

Answer 10

chest leads:
V1 and V2 : right chest
V5 and V6: left chest
right BBB: show V1or V2 w/ QRS-R’ , V5 orV6 w/ wider QRS
left BBB: shows V1 or V2 wider QRS, V5orV6 w/ QRS-R’