Re: left axis deviation
|Why does left ventricular hypertrophy does not a cause left axis deviation??
When the left ventricle hypertrophies, it may rotate to the horizontal position , this is due to the increase in muscule mass on the left side. This would cause an increase in the voltage as measured by electrodes on the left lateral part of the precordium and may cause a greater voltage of the left arm electrode as well.
If the heart is originally horizontal and develops hypertrophy, there will be a considerable increase in voltage of the left arm lead, Lead I, and the left precordial leads and the axis is not shifted beyond - 30°. However, if the heart is originally vertrical in location, then there will be an increase in voltage of the left leg lead, and in Leads II and III, and also an increase in the voltage of the left precordial leads, but little shift in the axis is associated.
Left axis deviation which is more superior than - 30°, this is rare unless accompanied by left anterior hemiblock.
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