Lab 2 - Electrocardiography Flashcards
What does an EKG record?
recording of the electrical activity of the heart
What do the wave forms represent?
polarization and depolarization of the cardiac tissue
What 4 things does an EKG measure? (4)
- Rate and regularity of the heartbeat
- Size and position of the chambers
- Effects of medications
- Effects of pacemakers or other devices.
Why is a 12 Lead EKG only have 10 leads?
The final two are a little bit redundant so are left off.
Which leads are the limb leads?
Leads I, II, III
Which leads are the Chest/Precordial/Transverse Leads and what do they view?
V1 - Views Right Atria
V2 - Views Left Atria
V3 and V4 - View the Intraventricular Septum
V5 and V6 - View the lateral wall of the left ventrical
What are the Augmented Leads?
aVR, aVL, aVF
Which leads are the Anterior Chest Leads?
V1, V2, V3, V4
Which leads are the Lateral Wall of the Left Ventricle?
aVL, Lead I, V5 and V6
Which leads are the Inferior Chest?
Lead II, Lead III, and Lead aVF
Which leads are No Man’s Land?
aVR
Which lead is used in a single 6 second EKG strip?
Lead II
Which 6 leads record electrical signal in the frontal plane?
- Lead I
- Lead II
- Lead III
- aVR (right arm)
- aVL (left arm)
- aVF (left leg)
Which 6 leads record electrical signals in the transverse plane?
- V1
- V2
- V3
- V4
- V5
- V6
Where does the RA lead go?
Right Arm
Where do the hip leads often get placed in the hospital?
legs
Where does the LA lead go?
Left Arm
Where does the RL lead go?
Right Leg
Where does the LL lead go?
Left Leg
Where does the V1 lead go?
4th intercostal space to the right of the sternum
Where does the V2 lead go?
4th intercostal space to the left of the sternum
Where does the V3 lead go?
between electrodes 2 and 4
Where does the V4 lead go?
5th intercostal space in the mid-clavicular line
Where does the V5 lead go?
horizontally even with V4 in the left anterior axilla road
Where does the V6 lead go?
horizontally even with V4 and 5 in the mid axillary line
How many electrodes are there typically in a 12 lead ECG?
10 electrodes
Where is the normal conduction pathway in the heart? (4)
- SA node through atria
- AV Node (slowed here)
- Bundle of HIS
- Purkinje Fibers (travel through intraventricular septum to lateral wall of right and left ventricle.)
Is the right lateral wall ventricular wall or left lateral ventricular wall reached first during conduction?
Right is reached slightly faster than the left.
Is the SA or AV node the primary pacemaker?
SA Node, AV node is backup pacer
What is the BPM range of the SA node?
60-100 beats per minute
What is the BPM range of the AV node?
40-60 beats per minute
T/F: all myocardial cells can act as a pacemaker.
TRUE: all myocardial cells can act as a pacemaker in the absence of other pacers and as a result of pathology. Pacer location directly affects cardiac function.
What is the horizontal axis in ECG tracing?
time
What is vertical axis in ECG tracing?
amplitude
How many seconds is an EKG strip by convention?
6 seconds
What do the small blocks in an ECG strip represent?
0.04 seconds
What do the large blocks in an ECG strip represent?
0.20 seconds and 0.5mV amplitude
Where is the P wave and what does it represent?
- P wave is first wave and is normally an upward wave
- Represents atrial depolarization
What does the QRS complex begin with and what is the Q, R, and S? What does the QRS represent?
Q - downward deflection (polarization)
R - upward deflection (depolarization)
S - downward deflection (polarization)
Represents ventricular depolarization and contraction (also atrial repolarization but not seen)
What is the T wave and what does it represent?
- Normally upward wave.
- Represents ventricular repolarization
What is the U wave?
Usually not observable upward wave.
Represents recovery of perkinje fibers.
What is the 8 step procedure for reading a EKG strip?
- Rhythm
- Rate
- P Wave
- PR Interval
- QRS complex
- T wave
- QT interval
- ST segment
Where is the PR interval?
Start of P wave to start of QRS complex
Where is the PR segment?
End of P wave to start of QRS complex
Where is the QT interval?
Start of QRS complex to end of T wave
Where is the ST segment?
End of QRS complex to start of T Wave.
What do you look at and for when checking Ventricular Rhythm?
Look at R to R interval for ventricular rhythm (spikes)
-Are they regularly spaced? (equidistant from one another, 10% variance is acceptable.)
What do you look at and for when checking Atrial Rhythm?
Look at the P to P intervals
-Same regularly spacing
What can cause minor variations in the Atrial Rhythm?
breathing
How do you identify what you see on a strip?
- Regularly / Irregularly - is is spaced out the same and repeated
- Regular / Irregular - is the wave form regular or irregular
How do you calculate rate?
Method 1 - Count the QRS complexes over a 6 second period and multiply by 10
Method 2 and 3 are more complicated
What does the P wave represent?
Atrial Depolarization
How many P waves should there be and where should it be located?
Should be one per QRS and should precede the QRS
What is the normal amplitude of the P wave?
0.05 to 0.25
What is the normal duration of the P wave?
0.06 to 0.11
What should the P wave look like?
Smooth and rounded
What 3 things should you look for when looking at a P wave?
- Present?
- Regular?
- Same shape?
When you have right atrial enlargement, what will you see?
P wave greater than 2.5mm high ( = P Pulmonale)
When you have left atrial enlargement, what will you see?
P wave greater than 120ms (=P Mitrale)
What does the PR interval represent?
Conduction time (remember that the AV node slows conduction to give atria time to fire and ventricles time to fill)
How do you measure the PR interval?
Measure from where the P wave beings to the beginning of the QRS complex
How long should the PR interval be?
.12 to .20 second in adults?
How will the PR interval change in older adults?
It will be longer
How will the PR interval change with increased heart rate?
it will be shorter
What should you look for in a PR interval?
Are they constant.
What does the QRS complex represent?
Ventricular Depolarization
Is the QRS complex or P wave larger?
QRS complex
Where do you measure the QRS complex from?
end of PR interval to the end of the S wave
How long should the QRP complex be?
.08-12 seconds
What should you look for in a QRS complex?
should look similar to each other
Where in the conduction pathway is a Ventricular Dysrhythmia?
Below the AV node so outside of that pathway in the bundle of HIS in the left and right pathway of the purkinji fibers.
With a Ventricular Dysrhythmia, what are you looking for on the strip?
“Wide and Weird” with QRS duration > .12s
What is a Ventricular Dysrhythmia?
Leads to uncoordinated ventricular contraction and decreased ventricular ejection and low blood pressure wave and possible poor perfusion.
What is the most common type of Ventricular Dysrhythmia?
Premature Ventricular Contraction (PVC)
What does a PVC strip look like and what might the patient feel?
-QRS is early and followed by a pause, then back to normal rhythm.
