Chapter 6 (Exam 2) Flashcards
What happens in a Sinus Block
SA node misfires and misses a cycle, resumes with previous rhythm
What is Sick Sinus Syndrome and how does it differ vs Sinus Block?
There is SA node dysfunction so it misses consistent cycles whereas an SA block is usually once
How many degree of blocks?
3
What happens in 1st degree block?
AV node conduction is prolonged
How to identify 1st degree heart block?
PR interval longer than 0.2 seconds
How long should a NORMAL PR interval be?
Only one big box (less than 0.2 seconds)
What are the two types of 2nd degree heart blocks?
Wenckebach / Mobitz
What is a type I 2nd degree heart block/Wenckebach
A block of the AV node where the PR interval gets progressively longer and then a drop QRS occurs
What is a Mobitz? What occurs?
A block of the Purkinje fibers / PR interval remains constant but a drop QRS still occurs
What is a 3rd degree heart block
A total block of atrial depolarization conduction to the ventricles/ atria and ventricles fire at random
In 3rd degree blocks, how does the QRS complex look?
Wide
In 3rd degree blocks the QRS complexes look similar to PVCs, why are they not considered PVCs?
The ventricular rhythm is not happening Prematurely
Describe how the PR interval looks in 3rd degree heart blocks
It is all over the place/changing
After the 3 degrees of heart blocks, what other kind of blocks are discussed in chapter 6?
Bundle Branch Blocks
What is a bundle branch block?
A block of conduction in either the left or right bundle
A bundle branch block delays ____ of the ____
Depolarization // ventricles
In a bundle branch block, how do the ventricles contract? How should they normally contract?
They contract at different times // they should normally contract simultaneously
Bundle branch block has a QRS that is wider than
0.12 s (3 little boxes)
Bundle branch block has varying ___ waves
R waves (R’)
For a BBB (bundle branch block) you would look at which leads?
Chest leads
For RBBB which chest leads would you look at?
V1 & V2
In RBBB what do you see?
“Bunny ears” - QRS goes up and down, then back up a 2nd time and down. (Can also be a negative deflection)
What leads do you look at for LBBB?
V5 and V6
What do you see in a LBBB?
QRS goes up, then at the peak it flattens out in and upward or downward slope, then finally comes back down
