Transcript ecg and heart functi..
ECG AND HEART FUNCTION ECG AND EXERCISE
Instructor Terry Wiseth
What Do I Need To Hand In For This Lab?
1) ECG Tracing Data Table At Rest 2) ECG Tracing Data Table After Exercise 3) Labeled Sketch of ECG Tracing At Rest 4) Labeled Sketch of ECG Tracing After Exercise 5) Answers to Questions 1-8
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You can use the links below to print off the data tables, graphs and questions you will need to hand in with this lab.
ECG Data Table At Rest After Exercise ECG Tracing Graph Paper
(You will want 2 copies of this)
Questions 1-8
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Click on the
g ram (ECG) can be monitored in the laboratory and gives information on the electrical activity of the mV atria and ventricles during the cardiac cycle. sec sec Time DATA ACQUISITION UNIT Stimulator Outputs + Recording Inputs 1 Start Recording Stop Recording Power 2 sec Monitor ECG Sensor
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The cardiac cycle consists of a contraction of the atria and then the ventricles, followed by a period of rest. An impulse from the sinoatrial node produces a contraction of the atria and then excites the ventricles via the atrioventricular node.
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The currents produced by these impulses are recorded as the e lectro c ardio g ram or ECG, and the various waves can be correlated with the contractions of the atria and ventricles. An ECG is also called an EKG or e lectro k ardio g ram.
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We can summarize an ECG tracing in the image below. Each of the waves or spikes on the tracing can be represented with letters to indicate changes in electrical actions within the heart.
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It is easy to monitor a subjects electrocardiogram (ECG) in the lab and determine any changes provoked by exercise. In this lab the intervals between the various components of the ECG are measured from a volunteer at REST and immediately after EXERCISE , when the heart rate is elevated. The results will help to see how changes in physical activity affect heart function.
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Exercise increases the cardiac output by increasing 1) stroke volume and 2) heart rate. This lab compares the ECG from a volunteer at rest and during recovery from exercise. This is achieved by measuring the P-Q , Q-T and R-R time intervals and the QRS Complex amplitude to see which are affected by exercise . Study the image below to identify the various parts of the ECG tracing.
R P Ventricular Contraction PQ Q Atrial Contraction S QT QRS Complex Amplitude T Click on the Image or here to view a printable image
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The PQ Interval represents the atrial contraction. The length in time of the PQ interval can infer the strength of the atrial contraction. The QT Interval represents the contraction and relaxation of the ventricles. The length in time of the QT Interval can infer the strength of the ventricular contraciton.
P R Ventricular Contraction PQ Q Atrial Contraction S QRS Complex Amplitude T Click on the Image or here to view a printable image QT
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During exercise there is an increase in the amount of blood circulating around the body. Activation of the sympathetic nervous system increases cardiac output by modifying heart function in two ways:
1) The Stroke Volume Increases 2) The Heart Rate Increases
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1) The Stroke Volume Increases
The volume of blood in the heart before contraction increases and the volume of the blood in the heart after contraction decreases. Thus the Stroke Volume amount of blood ejected from either (the ventricle during each cardiac cycle) increases because there is more blood in the ventricles before contraction and less remaining in the ventricles after contraction.
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Comparisons of Stroke Volumes can be inferred by the relative amplitude of the QRS complex of an ECG tracing at rest and after exercise.
Amplitude is measured in millivolts (mV) and can be found on the vertical axis of the ECG tracing. A larger amplitude (mV) reading would indicate a more forceful ventricular contraction. A more forceful ventricular contraction causes more blood to be ejected during a cardiac cycle and thus an increased Stroke Volume .
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A measure of Stroke Volume can be inferred by the amplitude of the QRS complex of an ECG tracing.
Amplitude mV sec Time sec sec
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2) The Heart Rate Increases
The number of cardiac cycles (contractions) per minute increases. The heart rate increase is a result of the excess CO 2 produced by exercising muscles. mV AT REST One contraction each second would represent a heart rate of 60 beats per minute sec Time sec sec
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mV
ECG
Spikes sec Time sec sec The image to the left is a tracing of an ECG reading. The spikes can be thought to represent one heart beat. From the tracing given here we can see that there is a spike every second.
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mV
ECG
Spikes sec Time sec sec A spike each second would represent a heart rate of 60 beats per minute. As well, a spike every 0.5 seconds would represent a heart rate of 120 beats per minute.
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ECG Sensor DATA ACQUISITION UNIT Stimulator Outputs + Power Recording Inputs 1 2
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mV sec Time sec Start Recording Stop Recording ZOOM PRINT sec Monitor During this experiment you will display an ECG from a volunteer at rest and during recovery from exercise. To Start click the Red power control button to turn on the Data Acquisition Unit.
ECG Sensor DATA ACQUISITION UNIT Stimulator Outputs + Power Recording Inputs 1 2
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mV sec Time sec Start Recording Stop Recording ZOOM PRINT sec Monitor Click on the Blue lead from the ECG Sensor to plug it into Recording Input #1. The Red , Green and Black sensors on the table are radio telemetry sensors and will relay signals to the ECG Sensor.
ECG Sensor DATA ACQUISITION UNIT Stimulator Outputs + Power Recording Inputs 1 2
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mV sec Time sec Start Recording Stop Recording ZOOM PRINT sec Monitor Click on the Green Red electrode to connect it to the left wrist of the volunteer. Next click on the and Black electrodes to place them on the right foot and the right wrist respectively.
You should click on the STOP RECORDING button at this time ECG Sensor DATA ACQUISITION UNIT Stimulator Outputs + Power Recording Inputs 1 2 At Rest mV sec Time sec Start Recording
ZOOM PRINT sec Monitor Start Recording the ECG waves by clicking on the Green button on the monitor. The ECG tracings will continue for about 40 seconds and will then stop. You should click on the Red button to stop recording.
P R Ventricular Contraction QRS Complex Amplitude T PQ Q Atrial Contraction S QT mV ECG Sensor DATA ACQUISITION UNIT Stimulator Outputs + Power Recording Inputs 1 2
sec Time sec Start Recording Stop Recording
PRINT sec Monitor Click on the blue ZOOM button above to see a larger view of the ECG. Click on the yellow PRINT button view a printable version. Enter your data in the Data Table for At Rest.
mV DATA ACQUISITION UNIT Stimulator Outputs + Power Recording Inputs 1 2 ECG Sensor
You will be notified what to do next, The exercise is now complete.
when the subject has exercised the Click Here to go to the prescribed time. Please be patient.
sec Time sec Start Recording Stop Recording ZOOM PRINT sec Monitor We will now have the subject exercise by running in place for a prescribed period of time. Click on the subject above to begin exercising. When the exercise is completed we will monitor the ECG once again.
P R Ventricular Contraction QRS Complex Amplitude T PQ Atrial Q Contraction S QT ECG Sensor DATA ACQUISITION UNIT Stimulator Outputs + Power Recording Inputs 1 2 After Exercise mV sec Time sec Start Recording
ZOOM PRINT sec Monitor Start Recording the ECG waves by clicking on the Green button on the monitor. The ECG tracings will continue for about 40 seconds and will then stop. You should click on the Red button to stop recording.
PERFORM THE FOLLOWING SKETCHES
1) Sketch an image of the ECG tracing taken from the subject at Rest. Include at least three cycles in your sketch. Label the PQRST landmarks of one of the cycles.
ECG TRACING PAPER 2) Sketch an image of the ECG tracing taken from the subject after Exercise. Include at least three cycles in your sketch. Label the PQRST landmarks of one of the cycles
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ECG TRACING PAPER Click Here to View a Printable ECG Graph Paper
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Answer The Following Questions 1) Which component of the ECG coincides with contraction of the ventricles?
2) Which component of the ECG coincides with contraction of the atria?
3) What is the heart rate of the subject at rest?
4) What is the heart rate of the subject after exercise?
5) Describe at least two differences between the ECG tracings of the subject at rest and after exercise.
6) Why is the amplitude of the ECG tracing of the subject after exercise higher than when measured at rest?
7) Tachycardia is a term used to indicate a rapid heart rate. Which of the two ECG tracings performed indicate tachycardia?
8) Sinus rhythm is a term used to describe normal heart rate. Which of the two ECG tracings performed indicate sinus rhythm?
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You have now collected the data you need to finish the lab. Be sure that you include the following in your lab report. You can click on each of the following to link to them.
1) ECG Tracing Data Table At Rest 2) ECG Tracing Data Table After Exercise 3) Labeled Sketch of ECG Tracing At Rest 4) Labeled Sketch of ECG Tracing After Exercise 5) Answers to Questions 1-8 Click Here to End the Lab
1.5
Click to View a Printable Version of blank ECG Tracing Paper 1.0
mV 0.5
Click to View a Printable Version of this Image 0 Click to View ECG Data Table at Rest sec Time sec sec
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Monitor Sketch the ECG tracing above. You can use the red link shown above to print out a blank ECG tracing graph. Using the time measuring bars and the mV scale on the left, find the time intervals for the following: R-R Interval, P-Q Interval, Q-T Interval, Amplitude of QRS Complex.
RR Interval PQ Interval QT Interval QRS Amplitude ECG Tracings Data Table at REST Time seconds Amplitude mV Heart Rate HR = 60 / RR Interval Click to View a Printable Version of the ECG Data Table at Rest
After entering the data from the ECG tracing calculate the Heart Rate at REST by using the formula given in the table.
1.5
Click to View a Printable Version of ECG Tracing Paper 1.0
mV 0.5
Click to View a Printable Version of this Image 0 Click to View ECG Data Table After Exercise sec Time sec sec Monitor
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Sketch the ECG tracing above. You can use the link shown above to print out a blank ECG tracing graph. Using the time measuring bars and the mV scale on the left, find the time intervals for the following: R-R Interval, P-Q Interval, Q-T Interval, Amplitude of QRS Complex.
RR Interval PQ Interval QT Interval QRS Amplitude ECG Tracings Data Table After Exercise Time seconds Amplitude mV Heart Rate HR = 60 / RR Interval Click to View a Printable Version of the ECG Data Table After Exercise
After entering the data from the ECG tracing calculate the Heart Rate after EXERCISE by using the formula given in the table.