Normal ECG:
Rate and Rhythm
Read chapters 4 and 22
ECG Interpretation*
Standardization
Rate
1. RR interval
2. Heart rate
Rhythm
3. PP interval
4. P wave
width, height, shape, etc.
5. PR interval
6. QRS
width (and height)
*See Chapter 22
ECG Interpretation
Univ. of Wisconsin Medical School
•
http://www.fammed.wisc.edu/pcc/ecg/
The Normal ECG
Normal = normal sinus rhythm
Rate
1. R-R interval
Is it regular?
2. What is the heart rate?
300, 150, 100, 75, 60, 50
300 / (# of large boxes)
1500 / (# of small boxes)
Count the number of cardiac cycles in 10 seconds
and multiple by 6.
Rate
Bradycardia
less than 60 bpm
Tachycardia
greater than 100 bpm
Rate
3. P-P interval
Rhythm
4. P wave
5. PR interval
6. QRS
4. P Wave
Lead II and aVR
Positive in II
Negative in aVR
< 2.5 mm in amplitude
< 0.12 sec. in width
Normal P Wave
Normal direction of atrial
depolarization
aVR?
II?
Figures 4-2 and 4-3
Abnormal P Wave
Direction of atrial depolarization
with junction rhythm
This is an example of
a retrograde
conduction
aVR?
II?
P wave
The same direction as QRS
Only one P wave in front of QRS
Do all the P waves look alike?
5. PR interval
0.12 - 0.20 seconds
6. QRS Complex
What is the width? (less than 0.10 seconds)
Do all the QRS waves in the same lead look alike?
R wave progression
Axis
Abnormal Q waves (infarction)
QRS Complex
Q waves
Normal QRS
Two phases
brief phase; depolarization of ventricular septum
longer phase; depolarization of both ventricles but
the left is larger
First Phase
Depolarization of
ventricular septum
Second Phase
Depolarization of both
ventricles but the left is
larger
Precordial Leads
V6
V1
Normal QRS
V6?
V6?
V1?
Fig. 4-6
V1?
Normal QRS
V1
V6
Normal QRS
• Septal r wave
• Septal q wave
6. QRS Complex
R wave progression
Normal R Wave Progression
Transition Zone?
R Wave Progression
Transition Zone?
Transition Zone
Figure 4-7
Early & Delayed Transition
V1
V2
V3
V4
• Figure 4-7
V5
V6
6. QRS Complex
What is the electrical axis?
normal
left axis deviation
right axis deviation
extreme axis deviation
7. St Segment
ST segment elevation or depression
(see chapters 8 & 9)
8. T Wave
Normally positive where QRS wave is positive
V3- V6 and II, but negative in aVR
Abnormally tall T waves
Practice
ECG Library
http://www.ecglibrary.com/ecghome.html
ECG: The Art of Interpretation
http://www.12leadecg.com/full/
Normal
Not normal PR interval Mobitz Type II block
Not normal
LAD, R wave progression
RBB w/inferior MI
Not normal First degree block, left atrial enlargement, left bundle branch
block, & inferior MI
Not normal
Atrial fibrillation
Normal
Not normal
Junctional rhythm
Not normal
LAD, late R wave progression
Acute MI
Not normal
Premature ventricular contractions
Not normal
Ventricular tachycardia: note fast rate and wide bizarre QRS.
Normal
Not normal
Second degree AV block - type II
Not normal
RAD, R wave progression
Not normal
Third degree AV block
Not normal
Right bundle branch block. Note the wide QRS waves
Normal
Not normal
Left bundle branch block. Note the wide QRS waves
a. yes
b. vertical
c. V3
d. yes
e. yes
f. yes
2. No. Although there are P waves, they are negative.
negative P waves indicate a retrograde conduction likely
coming from the AV junction.