Electrical axis

  is the sum of the currents that are formed during ventricular depolarization (electrical axis of the QRS).

  Similar to measurement of the QRS complex axis, P and T waves axis can also be measured.

      In daily practice, measurement of QRS axis is usually sufficient.

      Unless stated otherwise, the electrical axis mentioned in this website will refer to QRS axis.

  Two factors determine the electrical axis of QRS complex:

            1- The position of heart in the chest

            2- Direction of the electrical activation in ventricular myocardium.

Horizontal heart refers to horizontal QRS axis (as in obese subjects).

Vertical heart refers vertical QRS axis (as in asthenic people or patients with emphysema).

  Determination of electrical axis is useful only in a few cardiac conditions.