Funds 3, EKG/ECG Preparation Flashcards
What does an EKG assess?
The Conductive System of the Heart
How is a resting heart cell charged?
It is negatively charged on the inside (It’s Polarized)
A resting heart cell has a membrane that is-
Impermeable
A resting heart cell has a lot of what on the outside of its membrane?
Sodium
What happens whenever a resting heart cell receives a jolt of electricity?
It becomes a Depolarized (Less Negative) heart cell
What happens to a resting heart cell’s membrane whenever it receives a jolt of electricity?
It becomes Permeable
Whenever a heart cell becomes permeable, what does the sodium outside of the heart cell do?
It enters the heart cell
(Sodium is positive, so the cell becomes less negative)
Depolarized heart cells cause the heart to do what?
Contract
When a depolarized cell starts becoming relaxed again, it is-
Repolarized (Going back to a negative state)
Depolarization leads to-
Contraction
Repolarization leads to -
Relaxation
Conductive system order?
SA Node —> Bachmann’s Bundle —> AV Node —> Bundle of HIS —> Left & Right Bundle Branches —> Purkinje Fibers
Where is the SA Node located?
The Upper Part of the Right Atrium
The Pacemaker of the heart =
The SA Node
This node keeps your heart beating at a normal rate (60-100 BPM) =
SA Node
What is the SA node responsible for?
Making both of the Atria contract
(Atrial Depolarization)
What does the Bachmann’s Bundle do?
It allows the SA Node to reach the Left Atrium to make it contract
This node is called the Gatekeeper =
AV Node
What does the AV Node do?
It helps delay or slow impulses a little bit so that the atria can fully empty themselves into the ventricles
What are the Bundle of HIS and the Purkinje Fibers responsible for?
Ventricular Contractions
(Ventricle Depolarization)
When should the AV Node fire?
Whenever the Atria are empty
Each box of an EKG strip represents-
A measurement of time
The tiny boxes in an EKG strip represent-
0.04 Seconds
The big boxes in an EKG strip represent-
0.20 Seconds
What does the P Wave represent?
Atrial Depolarization
What does the PR Segment demonstrate?
The delay created by the AV Node
This can be used to determine if the pt has a heart block =
The PR Interval
Where does the PR Interval begin and end?
Starts at the beginning of the P Wave, ends at the beginning of the QRS Interval
Where does the PR Segment start and end?
Begins after the P wave, ends when the QRS Interval begins
This interval demonstrates the time it takes for an electrical signal to go from the atria to reach the AV Node =
PR Interval
What does the QRS Complex represent?
Ventricular Depolarization
(This leads to the contraction of the ventricles)
(Atrial Repolarization also occurs here)
What is the J Point?
The point where the QRS Complex meets the ST Segment
What does the ST Segment represent?
Completion of Ventricular Depolarization and the beginning of Ventricular Repolarization
The ST Segment should look-
Flat (Isoelectric)
The ST Segment represents-
The resting of the heart cells
What does the T Wave represent?
The beginning of Ventricular Repolarization
What is the T Wave caused by?
The large size of the ventricles as they relax
When is Ventricular Repolarization complete?
The Isoelectric Line after the T Wave
Sometimes after the T Wave, there may be a U Wave, which can be caused by-
Hypokalemia
When does the QT Interval start and end?
Starts at the beginning of the QRS Complex, ends after the T Wave
What does the QT Interval represent?
The amount of time it takes for electrical signals to cause the ventricles to contract and then relax
So what’s the normal order of the waves/segments in an EKG?
P Wave —> PR Segment —> QRS Complex —> ST Segment —> T Wave —> Isoelectric Line
A P Wave should measure less than-
0.12 Seconds (3 Tiny Boxes)
The PR Interval should fall into the measurement range of-
0.12 Seconds to 0.20 Seconds
(3-5 Tiny Boxes)
If the PR Interval is over 0.20 seconds, it may indicate-
Heart Blockage
Where should the QRS Complex always be?
Always behind every P Wave
The QRS Complex shouldn’t measure anymore than-
0.12 Seconds (3 Tiny Boxes)
The ST Segment shouldn’t be elevated or depressed more than-
1 mm
What should the T Wave be like?
It should only appear after the QRS Complex
It should be round, and in the upright position in most leads
The QT Interval should be measured at a range of-
0.35 Seconds - 0.44 Seconds
(8 and 3 quarters of a tiny box to 11 tiny boxes long)
A prolonged QT Interval can increase the risk of-
Ventricular Dysrhythmias
(Such as Torsade De Pointes)
An EKG Strip should be how long?
6 Seconds (30 Tiny Boxes)
When assessing the PQRST, what should you assess?
Regularity
Rate
Resemblance
How would you assess the regularity of P Waves?
Is the length between each P Wave consistent?
How would you assess the rate of P Waves?
Count all of the P Waves in the six second strip, multiply the number by 10
What should a normal atrial rate be?
Between 60-100 BPM for sinus rhythm
Can there be more than one P Wave before every QRS Complex?
Yes, but if there’s more than one then that’s not good
When assessing the resemblance, rate, and regularity of a QRS Complex you are going to-
Treat it pretty much the same way you would if you were to assess a P Wave’s resemblance, regularity, and rate.
It should also be 60-100 bpm (this is your ventricular rate)
Do men and women have the same QT Interval? If not, how do they differ?
Men typically have shorter intervals than women
