Electrocardiography, Dr. D. Penney
Table 18. ANALYSIS OF ELECTROCARDIOGRAMS (continued......)
5) Axis - right / left axis deviation (ie. of the QRS complex); various methods can be used:
Find the lead with highest voltage; (+) deflection will point to the axis, (-) negative deflection will be 180 degrees to it.
Find a lead with equal voltages in the R and S waves; axis is 90 degrees to it.
Find two leads in which the QRS voltages are equal, both positive, both negative, or one positive & one negative - the axis is midway between.
(+) QRS in leads I & II means normal axis.
Note: Effect on the positive electrode is determined by:
Amount of mass being depolarized.
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