Download Exercise 33 ECG_PulseWave

NU – AP 2
iworx ECG & Pulse Wave
Exercise 33A (modified)
Electrocardiogram (ECG) and Pulse Wave Measurements
1. PURPOSE




Record an ECG on a human subject simultaneously with a pulse-wave measurement.
Calculate ECG and pulse parameters such as P-R, Q-T, and T-P intervals, as well as R-pulse interval and Pulse
wave Amplitude.
Correlate the electrical and circulatory events
Compare the ECG and pulse wave recordings during rest and after hand and leg exercise.
2. INTRODUCTION
The arterial system functions as a pressure reservoir. Blood enters the arterial system from the ventricles of
the heart in a pulsatile manner. However, when blood is leaving the arterial system through the capillaries, it
flows in a continuous manner. Between contractions, when the heart is relaxed and blood is not being pumped
into the arterial system, there is still enough pressure in the arterial system to move blood along the arteries.
The pressure in the arterial system exists because the elasticity of the arteries allows them to distend and recoil
and function as a pressure reservoir.
Signals from the autonomic nervous system control the tone of smooth muscle sphincters around the
arterioles. In this way, the autonomic nervous system can control the distribution of blood to the various organs
in the body. The distribution of blood that flows to a particular organ is influenced by local conditions. If there
are cells that require arterial blood, due to a decline in pH or oxygen levels or an increase in carbon dioxide
levels, smooth muscle sphincters open to permit blood into particular capillary beds.
When the ventricles contract, the ventricular pressure increases. That forces the atrioventricular valves to
close. Further contraction increases the ventricular pressure until it exceeds the arterial pressure. At this point,
when the arterial pressure is at its lowest point during the cardiac cycle (called diastolic pressure) the semilunar
valves are forced open, and blood flows into the artery. Blood entering the arterial system inflates the arteries a
little and increases blood pressure to a maximum, which is the systolic pressure.
At rest, the distribution of blood to a particular organ may be very different from that seen during exercise.
For example, the blood flow to the gut decreases during exercise, while blood flow to the skeletal muscles
increases dramatically. Furthermore, the amount of blood flowing around the circulatory system may be
increased several fold.
In the first part of this lab activity you will simultaneously record the electrocardiogram (ECG) and finger
pulse from a group member. In the second part, you will record EKG and finger pulse after arm exercise, and in
the third part, recordings will be performed after leg exercise.
3. EXPERIMENT SET-UP
1. Double-Click iWorx/LabScribe Software on Desktop to start the program
2. Click “Settings -> Select “AP_2 EKG Exercises”
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3. Open “ECG_ Circulation.”
4. Remove all jewelry, watches, etc. from wrists.
5. Use alcohol swabs to clean and scrub the 3 regions on the inside of the subject’s dominant forearm
where the electrodes will be placed.
6. Remove the plastic disk from a disposable electrode and snap lead wires onto the disposable electrodes
(Figure 1).
7. Attach the disposable electrodes on the regions describes below (Figure 2).
 RED (+1) LEAD is attached to the right wrist.
 BLACK (-1) LEAD is attached to the electrode connected to the left wrist.
 GREEN (C) LEAD (the ground) is attached to the electrode on the right wrist.
8. Place the plethysmograph on the volar surface (where the fingerprints are located) of the distal segment
of the subject’s middle finger, and wrap the Velcro™ strap (Figure 2).
Figure
a)
b)
c)
d)
1 – Sensors/instruments used in exercises 31 and 33
Stethoscope
Event Marker
Pulse Plethysmograph
EKG cable & Electrode lead wires
Figure 2 –Electrodes attached to the specified regions and
Plethysmograph is attached to the volar surface of the
middle finger
black
black
a
b
c
d
Green (ground)
4. PROCEDURES
1. PART 1 - Recording of Data while the Subject is Sitting Still (at Rest)
1. Your group member (Subject) should sit quietly with both hands on their laps in supine position.
***If you group member moves, the ECG trace will move off the top or bottom of the screen. If he or she
moves any muscles in the arms or upper body, electromyograms (EMGs) from the muscles will appear on the
ECG recording as noise
2. When the Subject is ready, Operator will start the recoding clicking on the Record button.
3. Click on the AutoScale button at the upper margin of the ECG, Pulse, and Pulse Integral channels. Your
recording should look like Figure 3.
• If the signal on either the ECG or the Pulse channel is upside down when compared to trace in Figure HH1-5 on page HH-1-3, click on the downward arrow to the left of the channel title and select the Invert
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function. The trace should now look similar to the one in the figure
• If a larger ECG signal is required, the electrodes should be moved from the wrists to the skin immediately
below each clavicle.
• If the pulse signal is small or noisy, adjust the tension on the strap holding the pulse plethysmograph to
the finger. When you have a suitable trace, type <Subject’s Name> Resting ECG/Pulse in the Mark box to the
right of theMark button. Press the Enter key on the keyboard to attach the comment to the data. Record for
a minute or two. Note the average resting heart rate (V2 –V1 = ….bpm) on Heat Rate channel
8. When the recording is completed Operator will;
 click on Stop to halt the recording.
 Save the file as “GroupName_ekgResting” on the Desktop of your computer. Make sure to
designate the file type as *.iwxdata.
Figure 3 – Recorder using the Stethoscope on one hand and
event marker on the other hand.
Figure 4 – A example of a good recording with minimal
amount of noise.
2. PART 2 - Recording of Data After the Subject Performed Hand Exercise
1. The subject will rhythmically squeeze the hand dynamometer until he or she can feel the fatigue on
forearm. By the meantime, the Operator should minimize the Heart Sounds channel.
2. Recording will be performed as described in Part 1, from #1 through #7, but excluding the heart
sounds.
3. Operator will record immediately after the Subject stops squeezing the hand dynamometer.
4. Operator will continue recording for 3 minutes or until the Subject’s pulse wave remains in a constant
level for 1 minute.
5. Operator will also type and enter the followings next to the Mark box to the right of Mark button;
 Type 0 second and press Enter key on keyboard when begin to record.
 Type 60 seconds and press Enter key on keyboard when 1 minute is passed while recording.
 Type 120 seconds and press Enter key on keyboard when 2 minutes is passed while recording.
6. When the recording is completed Operator will;
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

click on Stop to halt the recording.
Save the file as “GroupName_ekgHandExercise” on the Desktop of your computer. Make sure
to designate the file type as *.iwxdata.
3. PART 3 - Recording of Data After the Subject Performed Leg Exercise

First, the EMG wires will be unplugged from the electrodes, but electrodes will be left intact on Subject’s
skin.
 Then, the subject will perform some leg exercises such as running or jogging in the hallway outside the
classroom or around the parking lot for 3 to 5 minutes. By the meantime, the Operator should minimize
the Heart Sounds channel.
 Again, the recorder will be off duty and will NOT listen for heart sounds. Recording will be performed as
described in Part 1, from #1 through #7, but excluding the heart sounds.
 When the Subject comes back from exercise, the wires will be attached, and the Operator immediately
will begin recording.
*** While recording operator should check the Subject’s real time Heart Rate, (V2 –V1 = ….bpm) on
Heart Rate channel and make sure it was elevated after exercise. ***
 Operator will continue recording for 3 minutes or until the Subject’s heart rate returns to normal, as it
was recorded during the resting period.
 Operator will also type and enter the followings next to the Mark box to the right of Mark button;
 Type 0 second and press Enter key on keyboard when begin to record.
 Type 60 seconds and press Enter key on keyboard when 1 minute is passed while recording.
 Type 120 seconds and press Enter key on keyboard when 2 minutes is passed while recording.
2. When the recording is completed Operator will;
 click on Stop to halt the recording.
 Save the file as “GroupName_ekgLegExercise” on the Desktop of your computer. Make sure to
designate the file type as *.iwxdata.
Figure 5 – Shortcut buttons on LabScribe software
5. DATA ANALYSIS
I.
PART 1 – Analysis of Recorded Data while the Subject is Sitting Still (at Rest)
1. Scroll through the recording and find a section of data with four to six good ECG cycles in succession.
2. Four complete ECG cycles can be selected by;
i. Placing the cursors on either side of a group of four complete ECG cycles
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ii. Clicking the Zoom between Cursors button (Figure 5) on the toolbar to expand that segment to
the width of Main window.
3. Click on the Analysis window icon in the toolbar (Figure 5). You will see the mathematical functions
above the uppermost channel. Values for V2-V1 (y-axis, vertical), T2-T1 (x-axis, time), and Mean
(average between two cursors) from each channel can be seen across the top margin of each channel.
4. Using the Table 1 on the next page as a guide, place the two cursors on specified positions to determine
the values on data tables. When the cursors are in correct positions, the data can be obtained from the
numbers below V2-V1, T2-T1, and the Mean functions for the channel desired.
*** Data can be input on Excel file, AP2_HeartSounds_EKG_Tables_v1.xls or can be written down on the
printed data tables. ***
5. Analyze the data at or around 0 sec, 60 sec, and 120 sec. at the marked portions of your recording.
6. For each component record and fill out the data table 1, “Resting EKG Measurements and Heart Sounds”
for three times (for three different EKG cycles).
II.
PART 2 – Analysis of Recorded Data after the Subject Performed Hand Exercise
1. Perform the analysis as described above in Part 1. Refer to Table 1, but do not analyze R wave to “lub”
and R wave to “dub” intervals.
2. Analyze the data at or around 0 sec, 60 sec, and 120 sec. at the marked portions of your recording.
3. For each component record and fill out the data table 2, “EKG Measurements after ARM Exercise” for
three times (for three different EKG cycles).
III.
PART 3 – Analysis of Recorded Data after the Subject Performed Leg Exercise
4. Perform the analysis as described above in Part 1. Refer to Table 1, but do not analyze R wave to “lub”
and R wave to “dub” intervals.
5. Analyze the data at 0 sec, 60 sec, and 120 sec. at the marked portions of your recording.
6. For each component record and fill out the data table 3, “EKG Measurements after LEG Exercise” for
three times (for three different EKG cycles).
Table 1 – Guide to Measurements of EKG Components
Component
(Value to be
Measured)
How to Measure
Value to be Recorded
R wave to
“lub” interval
Place one cursor on the peak of R wave on ECG channel. Place the
second cursor on the onset (top of first vertical line) of event
marker on Heart Sounds channel.
T2 - T1 on either ECG or
Heart Sounds channel
R wave to
“dub” interval
Place one cursor on the peak of R wave on ECG channel. Place
the second cursor on the offset (top of second vertical line) of
event marker on Heart Sounds channel.
T2 - T1 on either ECG or
Heart Sounds channel
R wave
Amplitude
P – R Interval
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Place one cursor on the peak of Q wave before R wave and the
second cursor on the peak of the R wave on ECG channel.
Place one cursor at the beginning of P wave and the second
cursor at the beginning of QRS complex on ECG channel.
V2 - V1 on ECG channel
only
T2 - T1 on ECG channel only
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Q - T Interval
Place one cursor at the beginning of QRS complex and the
second cursor at the end T wave on ECG channel.
T2 - T1 on ECG channel only
T - P Interval
Place one cursor at the end of the T wave and place the second
cursor at the beginning of the following P wave on ECG channel.
T2 - T1 on ECG channel only
R wave to
Pulse Interval
Place one cursor on the peak of R wave on ECG channel. Place the
second cursor at the peak of the Pulse wave to its right on the
Pulse channel.
T2 - T1 on either ECG or
Pulse channel
Pulse wave
Amplitude
Place one cursor on the baseline before the Pulse wave and the
second cursor at the peak of the Pulse wave to its right on the
Pulse channel.
V2 - V1 on Pulse channel
only
Place one cursor on the peak of R wave and the second cursor on
the peak of adjacent R wave to its right on the EKG channel.
T2 - T1 on ECG channel only
Beat Period
(R – R Interval)
6. QUESTIONS
Fill in the table to answer the questions;
 If Increased compared to Resting value, write down “INC”
 If decreased compared to Resting value, write down “DEC”
 If stayed the same compared to Resting value, write down “SAME”
Measured After Arm Exercise
Mean Values
At 0 sec
At 60 sec
At 120 sec
Measured After Leg Exercise
At 0 sec
At 60 sec
At 120 sec
R wave Amp
P – R Interval
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Q – T Interval
T – P Interval
R – Pulse
Interval
Pulse Wave
Amp
Beat Period (T
to T Interval)
1. Using the formula below, calculate the average heart rate of the subject and write down on the table
below.
Heart Rate (beats/min) =
60 𝑠𝑒𝑐𝑜𝑛𝑑𝑠 𝑝𝑒𝑟 𝑚𝑖𝑛𝑢𝑡𝑒
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑠𝑒𝑐𝑜𝑛𝑑𝑠 𝑝𝑒𝑟 𝑏𝑒𝑎𝑡 (𝑀𝑒𝑎𝑛 𝐵𝑒𝑎𝑡 𝑃𝑒𝑟𝑖𝑜𝑑)
At Rest
At 0 sec.
Measured After ARM Exercise
At 60 sec
At 120 sec.
Measured After LEG Exercise
At 0 sec
At 60 sec.
At 120 sec
Mean Heart
Rate
a) After which exercise the Subject’s Heart Rate (HR) elevated the most?
b) Physiologically what are the factors involved in this kind of exercise that would cause HR to increase
more than the other one?
2. In your recordings, “lub” sound was expected to have occurred around the peak of R wave and the “dub”
sound around the peak of T wave.
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a) Can you correlate the mechanical event that signifies these sounds to electrical event (EKG waves) in
your recordings on the table below?
Heart Sound (Signifies a Mechanical Event)
Electrical Event (depolarization or repolarization of
cells)
“Lub” sound
“Dub” sound
b) Why do you think the first sound was expected to be heard around or just after the appearance of R
wave ?
3. By looking at your mean R wave Amplitude (the height of R wave, demonstrated the amount of
depolarization of the ventricles);
a) What are the differences between Rest, After Arm and After Leg Exercises?
b) Why do you think the mean R wave Amplitude decreased right after the Leg Exercise (expected to
return to rest value after 2 minutes or recovery period)
4. Mean Pulse wave Amplitude (Pulse wave height) is expected to decrease right after Leg Exercise and
increase after Arm Exercise ?
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a) How did your data reflect these changes?
b) What are the underlying physiological factors might have caused these changes? (Pulse wave amplitude
reflects the intensity of pulse which is directly related to the blood flow)
5. Q – T Interval reflects the total time during the depolarization and repolarization of ventricles.
a) In your data what happened to the Mean Q – T immediately after the Leg Exercise?
b) How do you relate Mean Q – T Interval to the mean Heart Rate (HR)? Did it increase or decrease with
increase or decrease in HR?
6. How the Mean T –P Interval changed after Arm and Leg Exercises? (Can you relate it to the changes in HR,
such as faster heart beat caused the heart to relax less than resting condtion just before the atrial
depolarization…etc)
7. Recovery Heart Rate refers to the heart’s ability to return to normal values after physical (aerobic) activity.
It is measured two minutes after exercise and is the most common measurement in determining
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cardiovascular fitness. It is calculated by subtracting the two min (120 sec) HR from the HR at 0 sec. The
bigger the value (quicker the HR returns the resting value) indicates a healthier heart and the smaller the
value indicates a less healthy heart.
Assume that two healthy subjects with similar physical conditions (age, gender, height, weight, etc)
performed Leg Exercises (under same conditions and time frame) and their mean HRs are determined from
EKG recordings on the table below;
Subject A
HR (at Rest)
72
HR (0 sec after Leg Exercise)
115
HR (120 sec after Leg Exercise)
80
Subject B
80
125
115
a) Which subject has the highest recovery HR and a healthier heart?
b) Why do you think this Subject would have a better recovery HR?
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