Introduction to the Physiology of ECG

  1. What is an electric dipole?
    Charge separation (pos and neg)
  2. How do dipoles generated by the heart produce the waves on ECG?
    • Depolarizing current that begins near negative electrode creates an upward deflection
    • Repolarizing current that begins near positive electrode creates a downward deflection
  3. If you have a negative electrode where the depolarization begins, what kind of deflection will you get on ECG?
    Upward
  4. If you have a positive electrode where the depolarization begins, what kind of deflection will you get on ECG?
    Downward
  5. What is the placement of the negative and positive electrodes for lead I?
    • Negative electrode on right arm
    • Positive electrode on left arm
  6. What is the placement of the negative and positive electrodes for lead II?
    • Negative electrode on right arm
    • Positive electrode on left leg
  7. What is the placement of the negative and positive electrodes for lead III?
    • Negative electrode on left arm
    • Positive electrode on left leg
  8. What is the mean electrical vector?
    The average of all the individual wave fronts (average direction of the wave)
  9. ECG uses 6 limb leads, some are unipolar and some bipolar. Which ones?
    • Leads I, II, III are bipolar
    • aVF, aVL, aVR are unipolar
  10. What is Einthenhoven’s Law?
    Lead I potential + lead III potential = lead II potential
  11. The magnitude of deflection is greatest when the mean vector of the current is ___________________ to the lead
    Parallel
  12. What does P wave represent?
    Atrial depolarization
  13. What does QRS complex represent?
    Ventricular depolarization
  14. What does T wave represent?
    Ventricular repolarization
  15. What does PR interval represent?
    Time between atrial and ventricular depolarization
  16. What does QT interval represent?
    Time between start of ventricular depolarization and end of ventricular repolarization
  17. What does ST segment represent?
    Time between end of ventricular depolarization and beginning of ventricular repolarization
  18. In what direction is the depolarization traveling in the heart during Q wave?
    From left ventricle to right, slight upwards left axis
  19. In what direction is the depolarization traveling in the heart during R wave?
    Down towards apex, parallel to lead II
  20. In what direction is the depolarization traveling in the heart during S wave?
    Upwards toward lead I
  21. The unipolar limb leads are all positive/negative, meaning any depolarization traveling toward the electrode will show a upward/downward wave
    • Positive
    • Upward
  22. What is the normal mean electrical vector (axis) for ventricular depolarization?
    -30 to 90 degrees
Author
stepha998
ID
344718
Card Set
Introduction to the Physiology of ECG
Description
ATSU
Updated