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QRS axis: Difference between revisions
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→Abnormal heartaxis
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==Abnormal heartaxis== | ==Abnormal heartaxis== | ||
The direction of the vector can changes under different circumstances: | The direction of the vector can changes under different circumstances: | ||
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#Infarcted tissue is electrically dead. No electrical activity is registered and the QRS vector turns away from the infarcted tissue | #Infarcted tissue is electrically dead. No electrical activity is registered and the QRS vector turns away from the infarcted tissue | ||
#In conduction problems, the axis deviates too. When the right ventricle depolarizes later than the left ventricle, the axis will turn to the right (RBBB). This is because the right ventricle will begin the contraction later and therefore will also finish later. In a normal situation the vector is influenced by the left ventricle but now only by the right ventricle. | #In conduction problems, the axis deviates too. When the right ventricle depolarizes later than the left ventricle, the axis will turn to the right (RBBB). This is because the right ventricle will begin the contraction later and therefore will also finish later. In a normal situation the vector is influenced by the left ventricle but now only by the right ventricle. | ||
[[Image:left_axis_dev.jpg|thumb|left| Heartaxis deviation to the left in case of an inferior infarct. Left anterior hemi Block is a common cause. A left axis is between -30 and -90 degrees. The axis is -30 degrees.]] | |||
[[Image:right_axis_dev.jpg|thumb|none| Heartaxis deviation to the right in right ventricular load, as in COPD or pulmonary embolism. A right axis is between +90 and +180 degrees. In this case the axis is +135 degrees]] | |||
==Left axis deviation== | ==Left axis deviation== | ||