Laboratory 2

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Laboratory 2

• The conduction system of the heart and
  electrocardiography

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Lab 2 Activities

• Anatomy of the internal conduction pathway of the
  heart.
• Biopac Exercise L05-ECG-1  Normal
  electrocardiogram (including the names of all
  waves, intervals, and segments, what they mean,
  and how they correlate to the parts of the
  cardiac cycle).

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Conduction System and Pacemakers

• Autorhythmic cells
• cardiac cells repeatedly fire spontaneous action
  potentials
• Autorhythmic cells the conduction system
• pacemakers
• SA node
• origin of cardiac excitation
• fires 60-100/min
• AV node
• conduction system
• AV bundle of His
• R and L bundle branches
• Purkinje fibers

Its as if the heart had only two motor units
the atria and the ventricles!
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The ECG
Below are illustrated the waves (deflections) of
a typical cardiac cycle.
R
P
T
Q
S
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The ECG
Waves, intervals and segments of one cardiac
cycle are illustrated below.
QRS complex
R
P
T
Q
PR PQ Interval
S
ST segment
QT interval
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BIOPAC NOTES

• During calibration
• If the beginning of the baseline is decreasing,
  redo the calibration.
• The baseline should be more or less constant
  (horizontal) during calibration.

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BIOPAC NOTES

• During data collection
• Treatment 1 Lying on the bench top or three
  chairs or at least with feet elevated in a second
  chair arms folded breathing normally
• Treatment 2 Sitting in a chair with arms folded
  and breathing normally
• Treatment 3 Sitting in a chair doing deep
  breathing record for 20 seconds after the first
  minute of deep breathing
• Treatment 4 record until resting rate returns
  after one minute of running in place

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BIOPAC NOTES

• During analysis
• Step 12. Make sure that box 2 reads none. The
  BPM data is useless as you are only looking at
  one wave.
• Be sure that you adjust the x-axis to show only
  2-3 cardiac cycles when analyzing your data.

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BIOPAC NOTES

• During analysis
• Be sure that you analyze 2 cardiac cycles for
  each segment. Calculate the average of the
  cycles!
• Do not select cardiac cycles that are right next
  to each other choose cycles from the middle of
  each half of the treatment segment.
• The PR interval (PQ interval) is really between
  the start of the P wave and the start of the Q
  wave.
• Do your best to identify wave transitions (Figure
  31.11). Be consistent!

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BIOPAC NOTES

• First procedure
• Relaxed, lying down.
• PR ( PQ) Interval
• 1 deltaT(2) 0.17000 sec
• 2 deltaT(2) 0.18500 sec
• AVG 0.18 sec
• QRS Complex
• 1 deltaT(2) 0.09600 sec
• 2 deltaT(2) 0.08400 sec
• AVG 0.09 sec
• QT Interval
• 1 deltaT(2) 0.40100 sec
• 2 deltaT(2) 0.39900 sec
• AVG 0.40 sec
• ST Segment
• 1 deltaT(2) 0.10100 sec

• Your journal output for each procedure should
  look like this.
• (1) You must calculate the averages.
• You must reset CH2 to bpm and highlight one
  cardiac cycle (R to R) to record the beats per
  minute rate for each treatment.
• Set Journal font to 8.

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BIOPAC NOTES
Your graph should look like this. Print a graph
for the first treatment (2 or 3 cycles). Make
sure you label the waves, intervals and segments
on each graph.
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Your Assignment

• Print a representative section of your ECG for
  one set of treatment data (lying down).
• Label the waves, intervals, and segments of a
  typical cardiac cycle on the ECG you print.
• Write the mean duration (delta T value) and bpm
  values that you recorded in your data journal
  next to the corresponding label on the ECG
  treatment graph (lying down) you printed.

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Important Biopac Note

• We have been experiencing several cases where
  Biopac crashes/locks up during data analysis.
• If this happens to you
• Switch to the task manager (ctl-alt-del).
• Go to the applications tab, select biopac and
  click on end task.
• Restart Biopac.
• Do not start a specific lesson!!!!
• If you click on a lesson, your previous data will
  be lost and you will have to redo the entire
  lesson!
• Click on review saved data to load the data
  file you were using.
• Please ask your instructor for help if you have
  any problems with the computer!

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End Lab 2