1 Bio212 Laboratory 3 The Electrocardiogram

2 Objectives for Today’s Lab Acquire a better understanding of the theory behind the ECG Record and analyze an ECG Computers set up in lab You will conduct the ECG on a lab partner Identify the components of a normal ECG Describe the phases of the cardiac cycle represented by each wave form on the ECG

3 A GREAT Book on ECGs This is you after reading the book…confident and no longer intimidated by ECGs!!

4 Electrocardiogram Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Time Millivolts PR Interval: 0.12 – 0.20 sec QT Interval: 0.20 – 0.40 sec QRS Interval: < 0.10 sec

5 The Bipolar Limb Leads We will be using only Lead II today, so the right arm will be negative, and the foot will be considered positive

6 The Electrocardiogram A wave of the ECG will be positive (up) when the positive wave is moving toward the positive electrode

7 Electrocardiogram and Heart Events Recall that the left foot electrode is POSITIVE, so when the wave of depolarization is moving toward the left foot, we get a positive (up) deflection on the ECG Right Arm (-) Left Foot (+)

8 Electrocardiogram and Heart Events Right Arm (-) Left Foot (+) Remember that the T-wave represents repolarization of the ventricles.

9 ECG Animation… NYU ECG tutorial siteNYU ECG tutorial site… This is available on Links to Explore for Lab 3

10 The Paper Chart ECG 0.2 sec 0.04 sec Small boxes are usually 1 mm on each side Ten mm high represents 1 mV

11 The Paper ECG Chart How long is the PR interval on this strip? The QT interval?

12 Calculating the Heart Rate

13 ECG Parameters What you will be doing in lab today… NOTE: This page is reproduced in your Laboratory Study Guide

14 What you should do in lab today… Read the Background and Introduction in your PowerLab Teaching Experiment handout See the “Directions for Use of Laptop Computer” at your station if you laptop is not already turned on Set up as described in the demonstration –Use the chart at each ECG station for electrode placement –Refer to Subject Preparation Steps 4-6 on page 3, if necessary for skin preparation and use of electrode gel Run the ECGs for each member of your group by following the Procedure in Exercise 1: ECG in a resting volunteer (page 5)

15 What you should do in lab today… After EACH member of your group has an ECG recorded, be sure to SAVE the ECG into a file!!! –Select File | Save As (to prevent overwriting someone else’s file with your data) –Enter a file name using your first and last name with no spaces as the file name, e.g., SueCidal). –File is saved to the Desktop, so when you retrieve it later to analyze the data, LOOK ON THE DESKTOP!

16 What you should do in lab today… After all members of your group have had an ECG recorded… –Analyze your own ECG (use the laptop software) Determine the heart rate for your ECG Examine the PR interval, QRS interval, and QT interval in your ECG and determine if these are within the normal range –Complete Part A, C, and D #3-6 and the Critical Thinking Application of your Laboratory Report and hand in with your ECG. Be sure your name is on all the sheets you hand in. Before you leave, please delete your ECG file from the Desktop