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Heart Axis calculation
Heart axis detection is one of the most important parts of calculating electrocardiography system. This
parameter provides the helpful information for medical diagnosis. Heart axis is average of all electrical
signals of the heart, in the other word it indicates the consequence vector of heart electrical activities.
The electrical axis can be calculated for P, QRS and T waves. among above axes, QRS axis is used
clinically more and can be calculated simply. Leads I, II, and III or aVF, aVL and aVR can be used to
calculate QRS axis. Each of these leads indicates electrical activity of heart in the specific direction.
Axes corresponding with each lead are indicated in figure 2-13. The relevant diseases according to
heart axis are indicated in figure 2-14. Normal heart axis (as shown) is between -30 and +90 degree.
Figure 2-13
Angles of different leads for the heart axis diagnose
Figure 2-14
Heart axis and the relevant diseases according to heart axis direction