Axis Deviation

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Axis Deviation

• Chapter 5

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Definition

• Electrical axis...
• The general direction in the frontal plane or
  toward which lead the QRS complex is
  predominately oriented
• ...the mean direction of depolarization through
  the frontal plane of the heart

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Mean QRS Axis Calculation
Lead II
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Mean QRS Axis Calculation

• General rules
• the mean QRS axis points midway between any two
  leads that show tall R waves of equal height
• the mean QRS axis is oriented at right angles
  (90) to any lead showing a bi-phasic complex

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Mean QRS Axis Calculation
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Mean QRS Axis Calculation
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Mean QRS Axis Calculation
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Mean QRS Axis Calculation
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Mean QRS Axis Calculation
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Normal versus Deviation
Left
3 ?
1 ?
2 ?
Right
90
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Axis Deviation
Left
Right
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Axis Deviation Criteria
LEAD I LEAD II (or Lead aVF or III)
Normal Positive Positive
LAD Positive Negative
RAD Negative Positive
Intermediate axis Negative Negative
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Axis Deviation

• RAD If R wave in III gt R wave in II
• LAD If R wave in aVL gt I and deep S wave in III

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Axis deviation
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Axis deviation
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Axis deviation
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What is the axis?
Right
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What is the axis?
Left
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What is the axis?
Normal
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What is the axis?
Left
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What is the axis?
Normal
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What is the axis?
Right
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Causes of Left Axis Deviation
FYI
left anterior hemiblock Q waves of inferior
myocardial infarction artificial cardiac
pacing emphysema hyperkalaemia Wolff-Park
inson-White syndrome - right sided accessory
pathway tricuspid atresia ostium primum
ASD injection of contrast into left coronary
artery note left ventricular hypertrophy is not
a cause left axis deviation
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Causes of Right Axis Deviation
FYI
normal finding in children and tall thin
adults right ventricular hypertrophy chronic
lung disease even without pulmonary
hypertension anterolateral myocardial
infarction left posterior hemiblock pulmonar
y embolus Wolff-Parkinson-White syndrome -
left sided accessory pathway atrial septal
defect ventricular septal defect