Normal ECG: Rate and Rhythm

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Normal ECG Rate and Rhythm

• Read chapters 4 and 22

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ECG Interpretation

• Standardization
• Rate
• RR interval
• Heart rate
• Rhythm
• PP interval
• P wave
• width, height, shape, etc.
• PR interval
• QRS
• width (and height)
• axis
• R wave progression
• abnormal Q waves
• ST segment
• T waves
• QT interval
• U waves

See Chapter 22
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ECG Interpretation

• Univ. of Wisconsin Medical School
• http//www.fammed.wisc.edu/pcc/ecg/

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The Normal ECG

• Normal normal sinus rhythm

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Rate

• R-R interval
• Is it regular?
• 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.

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Rate

• Bradycardia
• less than 60 bpm
• Tachycardia
• greater than 100 bpm

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Rate

1. P-P interval

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Rhythm

1. P wave
2. PR interval
3. QRS

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4. P Wave

• Lead II and aVR
• Positive in II
• Negative in aVR
• lt 2.5 mm in amplitude
• lt 0.12 sec. in width

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Normal P Wave
Normal direction of atrial depolarization
aVR?
II?
Figures 4-2 and 4-3
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Abnormal P Wave
Direction of atrial depolarization with junction
rhythm
aVR?
II?
This is an example of a retrograde conduction
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P wave

• The same direction as QRS
• Only one P wave in front of QRS
• Do all the P waves look alike?

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5. PR interval

• 0.12 - 0.20 seconds

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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)

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QRS Complex
Q waves
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Normal QRS

• Two phases
• brief phase depolarization of ventricular septum
• longer phase depolarization of both ventricles
  but the left is larger

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First Phase

• Depolarization of ventricular septum

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Second Phase

• Depolarization of both ventricles but the left is
  larger

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Precordial Leads
V6
V1
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Normal QRS
V6?
V6?
V1?
V1?
Fig. 4-6
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Normal QRS
V1
V6
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Normal QRS

• Septal r wave

• Septal q wave

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6. QRS Complex

• R wave progression

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Normal R Wave Progression
Transition Zone?
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R Wave Progression
Transition Zone?
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Transition Zone

• Figure 4-7

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Early Delayed Transition
V1 V2 V3 V4
V5 V6

• Figure 4-7

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6. QRS Complex

• What is the electrical axis?
• normal
• left axis deviation
• right axis deviation
• extreme axis deviation

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7. St Segment

• ST segment elevation or depression
• (see chapters 8 9)

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8. T Wave

• Normally positive where QRS wave is positive
• V3- V6 and II, but negative in aVR
• Abnormally tall T waves

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Practice

• ECG Library
• http//www.ecglibrary.com/ecghome.html
• ECG The Art of Interpretation
• http//www.12leadecg.com/full/

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Normal
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Not normal PR interval - Mobitz Type II block
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Not normal LAD, R wave progression RBB w/inferior
MI
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Not normal - First degree block, left atrial
enlargement, left bundle branch block, inferior
MI
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Not normal Atrial fibrillation
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Normal
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Not normal Junctional rhythm
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Not normal LAD, late R wave progression Acute MI
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Not normal Premature ventricular contractions
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Not normal Ventricular tachycardia note fast
rate and wide bizarre QRS.
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Normal
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Not normal Second degree AV block - type II
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Not normal RAD, R wave progression
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Not normal Third degree AV block
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Not normal Right bundle branch block. Note the
wide QRS waves
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Normal
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Not normal Left bundle branch block. Note the
wide QRS waves
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a. yes b. vertical c. V3 d. yes e. yes f. yes
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2. No. Although there are P waves, they are
negative. negative P waves indicate a retrograde
conduction likely coming from the AV junction.