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Electrophysiology Axis Deviation

Electrophysiology Axis Deviation. EXSC 531 Clinical Exercise Physiology J. Larry Durstine, PhD Professor and Chair Exercise Science Department School of Public Health University of South Carolina. Learning Objective.

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Electrophysiology Axis Deviation

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  1. ElectrophysiologyAxis Deviation EXSC 531 Clinical Exercise Physiology J. Larry Durstine, PhD Professor and Chair Exercise Science Department School of Public Health University of South Carolina

  2. Learning Objective • At the end of this lecture, students will be able to understand the concept of axis deviation and determine axis deviation with special considerations.

  3. Lecture Outline • Determine axis deviation • Understand normal physiologic reasons for deviation. • Understand pathologic reasons for deviation. • Steps for determination • Special consideration

  4. Axis Deviation Determination If we add up all the small vectors of ventricular depolarization (considering both direction and magnitude), we have one large “Mean QRS Vector” which represents the general direction of ventricular depolarization.

  5. Axis Deviation Determination In myocardial infarction there is a necrotic (dead) area of the heart that has lost its blood and does not depolarize. The unopposed vectors from the other side Draw the Mean QRS vector away from the infarct.

  6. Axis Deviation Determination Axis is the Mean QRS vector when give in degrees, and the normal axis range is 0 to +90o in the frontal plane.

  7. Axis Deviation Determination In the frontal plane, there are 4 possible axis quadrants where the Mean QRS Vector may point. Visualize this large circle on the patient’s chest in the frontal plane.

  8. Determination of Axis Deviation Now, by looking at the QRS complex in I and AVF, you can locate the Mean QRS Vector in an Axis quadrant (in the frontal plane as it relates to the patient)

  9. Degrees of Deviation

  10. Axis Deviation Determination • For this method we will use only the limb and augmented leads • Step 1 Determine quadrant • Check leads I and AVF • Step 2 Determine the isoelectric lead • Where the QRS has “nearly” equal positive and negative deflections • Step 3 Move into the determined quadrant (from step 1) at a 90 degree angle • Special consideration • If the isoelectric lead is I, what is the quadrant? • If the isoelectric lead is AVF, what is the quadrant?

  11. Determine Quadrant • Check leads I and AVF

  12. Determine the Isoelectric Lead

  13. Move at a Right Angle • Move into the determined quadrant (from step 1) at a 90 degree angle

  14. I II III R L F Determination R L of Axis I III II F • Determine Quadrant. • Determine Isoelectric lead. • Move at right angle toward quadrant.

  15. I II III R L F Determination R L of Axis I III II F • Determine Quadrant • Determine Isoelectric lead • Move at right angle toward quadrant

  16. I II III R L F 1. Determine Quadrant 3. Move at right angle toward quadrant Determination R L of Axis I III II F 2. Determine Isoelectric lead

  17. I II III R L F Determination R L of Axis I III II F • Determine Quadrant • Determine Isoelectric lead • Move at right angle toward quadrant

  18. I II III R L F Determination R L of Axis I III II F • Determine Quadrant • Determine Isoelectric lead • Move at right angle toward quadrant

  19. Lecture Outline • Determine axis deviation • Understand normal physiologic reasons for deviation. • Understand pathologic reasons for deviation. • Steps for determination • Special consideration

  20. Lead AVF Lead I R L I III II F Lead AVF Lead I Lead I Lead II Lead III avR avL avF F 1. Determine Quadrant 2. Determine Isoelectric lead 3. Move at right angle toward quadrant

  21. R L Lead I Lead I I AVF AVF II III F Lead I Lead II Lead III avR avL avF G 1. Determine Quadrant 2. Determine Isoelectric lead 3. Move at right angle toward quadrant

  22. Lecture Outline • Determine axis deviation • Understand normal physiologic reasons for deviation. • Understand pathologic reasons for deviation. • Steps for determination • Special consideration

  23. Thank you

  24. Determination of Axis Deviation • Mean vector • Physiologic reasons for deviation • Pathogenic reasons for deviation • Steps for determination • Determine quadrant • Check leads I and AVF • Determine the isoelectric lead • Move into the determined quadrant at a 90 degree angle • Special consideration • If the isoelectric lead is I, what is the quadrant? • If the isoelectric lead is AVF, what is the quadrant? Counting heart rates • R to R • Count off • Small box counting (1 and 5 contraction methods) • Three and six second • Know reasons for using each

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