The Normal ECG

1
The Normal ECG
2
Normal P Wave

• Negative in aVR
• Positive in II
• 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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(No Transcript)
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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
12
Normal QRS

• Septal r wave

• Septal q wave

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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 Transition

• Figure 4-7

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Delayed Transition

• Figure 4-7

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Limb Leads

• aVR
• predominately negative QRS and T
• rS, QS, or Qr pattern (Fig. 4-9)

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Limb Leads Electrical Position

• Electrical Position Mean QRS Axis
• horizontal QRS axis
• vertical QRS axis
• intermediate QRS axis

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Horizontal Axis

• I and aVL show qR
• II, III and aVF show rS or RS

• Figure 4-10

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Vertical Axis

• aVL (and sometimes I) show rS or RS
• II, III and aVF show qR

• Figure 4-11

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Intermediate Axis

• I, aVL, II, III and aVF can be predominately
  positive

• Figure 4-12