Cardiovascular Physiology Concepts
                                    Richard E. Klabunde, Ph.D.

Electrocardiogram Tutorial

1. What does an electrocardiogram measure and what do its component waveforms represent?  click here

2. What do each of the following intervals represent, and what is their normal range in seconds?  click here
   a.    PR interval
   b.    QRS duration
   c.    QT and QTc intervals

3. Where are the electrodes placed on the body for a 12-lead ECG?  click here

4. What is the difference between bipolar and unipolar leads?  click here

5. Where is the location of the positive electrode in each of the following limb leads: I, II, II, aV_R, aV_L, and aV_F?  click here

6. What is the axial reference system and what is the axis (in degrees) for each of the bipolar and unipolar limb leads?  click here

7. What are the rules for determining the direction of a vector of depolarization and repolarization relative to a given ECG lead?  click here

8. Describe, in terms of vectors, how the QRS complex is generated and why the QRS appears differently when viewed by different leads.   click here

9. What is the normal mean electrical axis for the heart?  What is a left and right axis deviation?  click here

10. How can the mean electrical axis be approximated by examining the relative amplitudes of limb leads?  click here

DISCLAIMER: These materials are for educational purposes only, and are not a source of medical decision-making advice.

© 1999-2008 Richard E. Klabunde, all rights reserved.