Axis%20Deviation

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Axis Deviation

• Chapter 5

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Limb leads

• Frontal plane

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LIMB LEADS
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LIMB LEADS
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Limb leads
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Definition

• Electrical axis...
• ...the mean direction of the QRS complex
• the general direction in the frontal plane
  towards which the QRS complex is predominately
  pointed

Left
Right
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Mean QRS Axis Calculation

• The general direction or toward which lead axis
  the the QRS complex is predominately oriented
• Frontal axis
• Only involves the 6 limb leads

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Mean QRS Axis Calculation
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Mean QRS Axis Calculation

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

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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
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Axis Deviation
Left
Right
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Axis deviation
?
?
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Axis deviation
?
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Axis deviation
?
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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