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EKG Review
Graph Paper
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P wave represents atrial depolarization
QRS represents ventricular depolarization and contraction.
T wave represents ventricular repolarization
U wave indicates the recovery of the Purkinje conduction fibers. This wave component may not be observable
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EKG interpretation should be performed using a standard five step procedure:
Rhythm
Rate
P Wave
PR Interval
QRS Interval
1.
2.
3.
4.
5.
Step 1. Is the Rhythm Regular or Irregular
Small variations of up to 10% are considered equal.
Step 2. What is the rate
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Count the number of QRS complexes over a 6 second interval. Multiply by 10 to determine heart rate.
The second method uses small boxes. Count the number of small boxes for a typical R-R interval.
Divide this number into 1500 to determine heart rate.
Step 3. P-wave
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Are they present?
Do they occur regularly?
Is there one P-wave for each QRS complex?
Are the P-Waves smooth, rounded, and upright?
Do all P-Waves have similar shapes?
Step 4. PR Interval
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Measure the interval from where the P wave begins until the beginning of the QRS complex
Normal 0.12 to 0.20 seconds (3 to 5 small boxes)
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Step 5. QRS Complex
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Measure the QRS complex from the end of the PR interval to the end of the S wave
Normally this interval is 0.10 seconds or less
1. Regular vs Irregular Rhythms
Regular Rhythms
1. NSR
2. SB
3. ST
4. 1st Degree
5. 2nd Degree Type II
6. 3rd Degree
7. Junctional
8. Idioventricular
9. Aflutter
Irregular Rhythms
1. Afib
2. Aflutter (can be both)
3. SA
4. WAP
5. 2nd Degree Type 1
2. Rate
Slow <60
Normal 60-100
Fast >100
1. SB
2. Junctional
3. Idioventricular
4. Afib (atypical)
5. 3rd Degree
1. NSR
2. Acc. Junctional
3. Acc. Idioventricular
4. SA
5. WAP
6. Afib
7. Aflutter
8. 2nd Degree Type 1
1. ST
2. Junc Tachycardia
3. SVT
4. Afib with RVR
5. PAT
3. P-wave
Present, Upright, Before QRS
1. NSR
2. SB
3. ST
4. Aflutter (lots of them)
5. 1st Degree AVB
6. 2nd Degree Type I
7. 2nd Degree Type II
Absent, Inverted, Varies
1. Idioventricular
2. 3rd Degree
3. Afib
4. Junctional
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8. Sinus Arrhythmia
9. Wandering Atrial Pacemaker
4. PR Interval
PR <.20
(Immeasurable)
1. NSR
2. SB
3. ST
4. SA
5. WAP
PR>.20
1. Afib
2. Aflutter
3. 2nd Degree Type II
4. 3rd Degree
5. Junctional/Idioventricular
1. 1st Degree
2. 2nd Degree Type I
5. QRS
Less than .12
1. NSR
2. SB
3. ST
Greater than .12
4. SA
5. WAP
6. Junc. Rhythms
1. Idioventricular
2. Left Bundle Branch Block
3. Right Bundle Branch Block
Lethal Arrthythmias
1. Ventricular Tachycardia
2. Ventricular Fibrillation
3. Torsades De Pointes
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Individual Cardiac Rhythms Components
SB
Regular
Rate 40-60
P wave normal
PR normal
QRS normal
SVT
Regular
Rate >150
P wave normal
PR interval normal
QRS normal
NSR
Regular
Rate 60-100
P normal
PR interval normal
QRS normal
Afib
Irregular
Rate: Atrial >400, Ventricular
variable
P wave absent or irractic
PR interval not measurable
QRS normal
Sinus Arrhythmia
Irregular
Rate 60-100 (may increase)
P wave normal
PR interval normal
QRS normal
Wandering Atrial Pacemaker
Irregular
Rate Normal
P wave changes shape (small)
PR interval varies due to
shape of P wave
QRS normal
Junctional Tachycardia
Regular
Rate 100-150
P wave hidden, inverted, or
after QRS
PR absent or short
QRS Normal
Accelerated Junctional
Regular
Rate 60-100
P wave hidden, inverted, or
after QRS
PR not measurable
QRS Normal
Accelerated Idioventricular
Regular
Rate 50-100
P wave absent
PR not measureable
QRS wide >.12 (looks like a
PVC)
First Degree Heart Block
Regular
Rate 60-100
P normal
PR >.20
QRS normal
2nd Degree Type II
Surprisingly Regular
Rate Have to count atrial and
Ventricular
P wave normal, but too many
before a QRS, not next to each
other
PR interval not measureable
QRS Normal
3rd Degree
Regular
Rate Count Separately (Slow)
P wave Normal shape and
size, may appear within QRS
complexes
PR absent
QRS normal or wide
ST
Regular
Rate 100-150
P normal
PR interval normal
QRS normal
Aflutter
Regular or Irregular
Rate: Atrial >350 Ventricular
60-100
P wave sawtooth, close
together
PR interval not measurable
QRS normal
Junctional
Regular
Rate 40-60
P wave hidden, inverted, or
after QRS
PR not measurable
QRS Normal
Idioventricular
Regular
Rate 30-40
P wave absent
PR not measureable
QRS wide >.12 (looks like a
PVC)
2nd Degree Type I
Irregular
Rate typically 60-100
P wave normal
PR interval progressively
longer until QRS drops
QRS normal