Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
60 Cards in this Set
- Front
- Back
If the direction of the lead is in parallele with the direction of the dipole, what type of deflection will be seen?
|
A positive deflection
|
|
What are 3 factors that affect the amplitude of electrical vectors?
|
1. Mass of muscle generating signal (hypertrophy = big vectors)
2. Conduction Velocity (fast = big) 3. Degree of cancellation of electrical forces |
|
What are the 6 frontal plane leads and what is their orientaiton?
|
I: 0
II: 60 III: 120 aVL: -30 aVR: -150 aVF: 90 |
|
What is the central terminal of wilson?
|
The "virtual" negative pole created in the back of the chest for the chest leads, created by combining the limb leads to create negative lead
|
|
What are the orientation of the 6 chest leads?
|
V1: out/slight right from chest
V2: slight left V3/4/5: Progressively more left V6: 90 to the left |
|
What are the 3 main waveforms seen in a normal EKG?
|
1. P wave
2. QRS complex 3. T wave |
|
The P wave represents what?
|
Atrial depolarization
|
|
The QRS complex represents what?
|
Ventricular Depolarization
|
|
The ST segment represents what?
|
Ventricular plateua
|
|
The T wave represents what?
|
Ventricular repolarization
|
|
Why is the SA node depolarization and AV node depolarization not seen on an EKG?
|
Too small volume of tissue
|
|
Why is atrial repolarization not seen?
|
Too slow of a process
|
|
What is a Q wave?
|
The first downward deflection of the QRS compelx
|
|
What is the R wave?
|
The first upward deflection of the QRS complex
|
|
What is the S wave?
|
The downward deflection after the R wave in the QRS complex
|
|
What is R'?
|
A second upright deflection in a QRS compelx
|
|
What is the 5 step process to analyzing an EKG?
|
1. Rate
2. Rhythm 3. Intervals (PR/QRS/QT) 4. QRS axis 5. Configuration (P wave/QRS/ST segment, T wave) |
|
Each large box in the EKG is how many seconds?
Small box? |
Big: .2 (200ms)
Small: .04 (40ms) |
|
How is HR calculated?
|
300 / # of big boxes
|
|
What items are looked at to determine rhythm?
|
1. Upright P waves in I, II, III, (and aVF)
2. Rate between 60-100 3. P wave precedes each QRS (when HR is <120) 4. Are QRS normal or wide? 5. Is ventricular rhythm regular? 6. Do p waves come from sinus node? |
|
The initial portion of the QRS wave represents what?
|
Depolarization of intraventricular septum
|
|
The mid/late portions of QRS complex represent what?
|
Right and left ventricular depolarization
|
|
Describe the direction of depolarization in the ventricles?
|
Depolarization spreads from left bundle, through the septum from the LV to RV
The creates vectors pointing to the right and anterior |
|
The orientation of ventricular depolarization gives what reading on V1 and V6?
|
V1: R wave
V6: Q wave |
|
In the middle/late parts of ventricular depol, where is the net vector pointing?
|
Toward the left ventricular apex
|
|
Normal rhythm is called what?
|
Normal Sinus Rhythm
|
|
Sinus rhythm with HR >100 is what?
<60? |
>100: Sinus tachycardia
<60: Sinus bradycardia |
|
What is the first step in determining the nature of an abnormal rhythm?
|
Determine whether it is supraventriucular or ventriuclar in nature
|
|
What does a supraventriuclar rhythm look like?
|
Have P wave before every QRS
QRS duration is normal (unless there is a conduction block in one of the bundle branches) |
|
What does ventricular rhythm look like?
|
Always associated with wide QRS (because activation of the rest of the ventricles doesn't utilized the rapid conduction His Purkinje system)
|
|
What are the 3 intervals that are measured?
|
PR, QRS, QT
|
|
What is the PR interval?
What does it represent? What is normal? |
From beginning of P wave to beginning of QRS complex
Represents delay between atrial and ventricular depolarization Normal: 0.12 - 0.20 sec |
|
What is QRS?
What does it represent? What is normal? |
Beginning to end of QRS
Represents time to depolarize entire ventricle Normal: <0.10 sec |
|
A long QRS indicates what?
|
Indicates either that there is either a conduction block in one of the bundle branches or that the beat is arising in ventricular muscle
|
|
What is QT?
|
ME haha
Beginning of QRS complex to end of T wave |
|
In a bundle branch block, will there be a P wave before the QRS?
|
YES
|
|
Will there be a P wave in front of the QRS in ventricular beats?
|
NO
|
|
What is the biggest factor to cause a change in the QT interval?
|
Change in the ventricular AP duration
|
|
What is normal for QT?
|
Should be about 0.40 seconds when HR is 60
|
|
What is the QRS axis?
|
The mean vector orientation of the QRS axis in the frontal plane
|
|
QRS axis is calculated using which leads?
|
Frontal leads
|
|
What is normal QRS?
|
-30 to +90
|
|
What is configuration?
|
The shape, morphology of the different waves (to be discussed in more detail in further lectures)
|
|
What is the first part of the ventricle to be activated during the beginning of the QRS?
What is the orientation vector |
Intraventricular septum
vector: LV to RV which is anteriorly and to the R |
|
How does septal depolariation appear in the V leads?
|
As small R wave in V1 and small Q wave in V6
|
|
During the middle of the QRS, where is the orientaion vector?
|
Points leftward, toward the ventricular apex
|
|
How should the QRS look on the V leads?
|
Should have characteristic progression of R wave size from V1 to V6
Should be negative in V1, positive in V6, I and II |
|
In which direction should a normal T wave point?
|
Same direction as QRS
|
|
If the T wave represents repolarization, why is it in the same direcition as QRS?
|
Because it has opposite orientation.
Depolarization: Endocardium to epicardium Repolarization: Epicardium to endocardium bc epicardial AP's are shorter |
|
What is AV block?
|
Delay or conduction failure in the conduction pathway between the atria and ventricles
|
|
What is first degree AV block?
|
One to one AV conduction with conduction delay
|
|
What is seen on the EKG is first degree AV block?
|
every p wave is followed by a QRS, but PR interval is greater than 0.20 seconds (one large box)
|
|
What is second degree AV block?
|
Intermittent conduction block between atria and ventricles
|
|
What is seen on the EKG is second degree AV block?
|
some P waves are followed by QRS complexes and some are not
|
|
What is third degree AV block?
|
Complete conduction block between Atria and Ventricles
|
|
What is seen on the EKG on third degree block?
|
P wave and QRS are regular, but are independent of each other. Sometimes might see P wave before, sometimes after
|
|
What is bundle branch block?
|
Block in his-purkinje bundles going to the ventricles
|
|
What are the best leads for diagnosing bundle branch block?
|
I, V1, and V6
|
|
What is seen on the EKG in R bundle branch block?
|
Left ventricular activation is normal, so first part of QRS is normal (R wave in I and V6)
Broad S wave in QRS in I and V6, and a broad R' in V1 - because RV is activated late Overall: "M" shaped pattern in V1: RSR' |
|
What is seen on the EKG in L bundle branch block?
|
Wide R wave in leads I, V6
Wide S wave in V1 Because RV is activated normally, but LV is activated late by slow conduction through ventricular muscle from RV |