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You're looking at two 12-lead ECG's taken on the same day. It is the same patient with no change in medical therapy, but the configuration of the QRS is different. Maybe one of the leads that was positive in the morning is negative now, or maybe it is just less positive than before.

One of the first things to check is the electrical axis of the heart.

Because each lead views the heart's electrical activity from a different perspective, the 12-lead electrocardiogram provides important documentation of changes in the propagation of depolarization of the heart. Changes in the electrical axis, which can be determined from the 12-lead ECG, often have clinical significance.

This program discusses one mechanism to determine the electrical axis of the heart. Topics that will be discussed are the six frontal plane leads and charges, the direction of a vector based on the QRS deflection, the hexaxial reference frame, the range of normal axis, the net deflection of a vector, how to determine the mean QRS vector and the causes of axis deviation.

To complete this course, you must do the following:

  • Read the Overview and Course Objectives.
  • Study the Terminology.
  • Read the course material.
  • Complete the Learning Activity.
  • Complete the Post Test with a score of 80% or more.

    The material is organized around the following categories:

  • Introduction
  • The Six Frontal Plane Leads and Charges
  • Direction of a Vector Based on the QRS Deflection
  • The Hexaxial Reference Frame
  • Range of Normal Axis
  • Net Deflection of a Vector
  • Determining the Mean QRS Vector
  • Causes of Axis Deviation
  • Conclusion

    The purpose of this program is to provide nurses an understanding of how to determine changes in the heart's electrical axis in performing cardiac monitoring for acute care, and the nursing implications of these changes.

    After completing this course, the learner should be able to:

  • Review the six frontal plane lead positions and charges.
  • Identify the direction of a vector based on the QRS deflection in relation to the electrodes of a given lead.
  • Synthesize the hexaxial reference frame for determination of axis.
  • Define the range of normal axis.
  • Calculate the net deflection (algebraic sum) of a vector. Utilize the limb leads to determine the mean QRS vector (axis).
  • Identify causes of axis deviation.
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    Determining Electrical Axis Online course
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