Cardiovascular Physiology Concepts Richard E. Klabunde, PhD

# Guided Learning: Electrocardiogram

Guided learning questions provide a systematic approach to learning by using a sequencing of the questions similar to how a topic would unfold in a traditional textbook. The student is encouraged to go not only to the initial link associated with each tutorial question, but also to use embedded hyperlinks to expand upon the physiological concepts associated with the question.

At the end of the guided learning questions, there is a link to an external website (testmoz.com) that has multiple choice and true/false questions that are associated with the topic. When the quiz results are given to the user after taking the quiz, links are provided back to specific cvphysiology.com pages to assist learning. Users need to register (free) on the testmoz.com site to access the quiz questions for the tutorial. No personal information is available to cvphysiology.com apart from the user provided login name and analysis of user performance on the quiz questions. This feedback is used to improve cvphysiology.com content and quiz questions.

## Guided Learning

1. What does an electrocardiogram measure, and what do its component waveforms represent?
2. What do each of the following intervals represent, and what is their normal range in seconds?
1. PR interval
2. QRS duration
3. QT and QTc intervals
3. How is the heart rate determined from a rhythm strip?
4. Where are the electrodes placed on the body for a 12-lead ECG?
5. What is the difference between bipolar and unipolar leads?
6. Where is the location of the positive electrode in each of the following limb leads: I, II, III, aVR, aVL, and aVF?
7. Which regions of the left ventricle are represented by the following pairs of chest leads: V1-V2, V3-V4, and V5-V6?
8. What is the axial reference system, and what is the axis (in degrees) for each of the bipolar and unipolar limb leads?
9. What are the rules for determining the direction of a vector of depolarization and repolarization relative to a given ECG lead?
10. Describe, in terms of vectors, how the QRS complex is generated and why the QRS appears differently when viewed by different leads.
11. What is the normal mean electrical axis of the heart? What is a left and right axis deviation?
12. How can the mean electrical axis be approximated by examining the relative amplitudes of limb leads?

## Link to Quiz Questions: testmoz.com/2479835

Revised 10/06/2023