Presentation on theme: "Robert J. Huszar, MD Instructor Patricia L. Thomas, MBA, RCIS"— Presentation transcript:
1 Robert J. Huszar, MD Instructor Patricia L. Thomas, MBA, RCIS The 12-Lead EKG Chapter 12Robert J. Huszar, MDInstructorPatricia L. Thomas, MBA, RCIS
2 Outline Electrical Axes and Vectors The electrical current, vectors, and the lead axisThe hexaxial reference figureThe QRS axisDetermination of Axis
3 Electrical Axes & Vectors Instantaneous cardiac vector-the electrical current generated by the depolarization or repolarization of the atria or ventricles at any given momentGraphically as an arrow that has magnitude, direction, and polarityLength of the shaft of the arrow represents the magnitude of the electrical currentOrientation or position of the arrow indicates the direction of flow of the electrical currentThe tip of the arrow represents the positive pole of the electrical currentThe tail is the negative pole
8 The Hexaxial Reference Figure Composite of the two triaxial reference figures (limb leads+ augmented leads)Purpose is to determine the direction of the QRS axisEach +& - pole is assigned a degree number 00 to 1800The top are given – numbersThe bottom are given + numbersNOT TO BE CONFUSED WITH the - & + poles of the lead axes
12 Calculate the Axis1. Calculate the algebraic sum of QRS in Leads I & III2. Plot the vector results on a triaxial reference system3. Draw the perpendicular until Lead I & III cross.4. Draw a separate line from the center to the intersection of the two perpendiculars gives the electrical axis.5. Determine location (normal, RAD or LAD)
15 THE END OF CHAPTER 12Hauszar Robert, Basic Dysrhythmias, Interpretation & Management, Third Edition, Mosby, Inc. 2002, ppScheidt, Stephen M.D., Basic Electrocardiography,CIBA-GEIGY Pharmaceuticals, 1986pp. 3,18,19
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