The Function of Electrocardiogram: a Laboratory Report

Abstract

The purpose of these lab exercises is to understand the function and importance of an electrocardiogram. This lab will demonstrate how stress levels or different elevations can affect human heart rate. Furthermore, the equipment used in the experiment will show the functions in the right and left arm; as well as, in the right and left ankles. Finally, the lab will serve a purpose as a way to know how to read an electrocardiogram and calculate the heart rate.

Introduction

An electrocardiogram can be used to record activity during the cardiac process of pumping and returning blood to the body and heart because of the electric current that spreads through the tissue of the heart and to the surface of the body.

By using four electrodes, one on your left and right wrist and one on the upper left and right foot. From that information a person is able to record the electrical potentials produced by the heart.

Beginning of the lab involved a reading from the electrocardiogram and then calculating the heart rate by comparing the waves to what the electrocardiogram reading said.

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The electrocardiogram is divided into five main parts. The first small peak is the P wave; it represents atrial depolarization (Eric, 2011). Next is the QRS complex; the QRS consist of the Q, R and S. The complex will occur because of the electrical events produced as the ventricles depolarize (Eric, 2011). Lastly, there is the T wave; it represents the ventricular repolarization (Eric, 2011).

The voltages recorded on an electrocardiogram can be compared to on table 28.

1 in the Ninth Edition Seeley’s laboratory manual. In the lab experiment, there will be a comparison of the bpm, PR interval, QRS complex, and the QT interval. All in which you have an average that you can see if you are in the “normal” range of. If someone has a bpm above a hundred; it is called Tachycardia (Eric, 2011). If someone has a bpm below sixty; it is called Bradycardia (Eric, 2011). Following bpm, you have the PR interval the normal for that range is 0.16-0.18 seconds (Eric, 2011). Continuing with the next one is QRS complex the normal for the complex is 0.08 seconds (Eric, 2011). In contrast, the QT interval normal is between 0.3-0.4 seconds (Eric, 2011). Each one of the tests can express something different in relation to your heart rate.

Purpose of the lab was to teach someone how to read an electrocardiogram but as well to know how to calculate heart rate. If there was vibration of the table or the position in which someone was standing/laying then it can affect the reading of the electrocardiogram.

Materials and Methods

The protocol for this lab experiment involved a few things. First off gather the machine that will be used to test the heart rate. Connect the MP30 unit to an electrical outlet with the power supply (Eric, 2011). Do not turn the MP30 quiet yet though. Plug in the SS2L lead cables, into the CBLSERA cable (Eric, 2011). From that point, all jewelry should be taken off and the electrodes should be placed above your inner wrist on both left and right arm also one electrode above your ankle on the left and right foot.

After putting the electrodes on, plug in the information that is asked: age and sex. Now connect the right arm lead to the right arm, the left arm lead to the left arm, the right ankle lead to the right ankle, and the left ankle lead to the left leg. At that point have a partner make sure blood pressure is not too high, then press okay. The reading will take ten seconds. Stand straight up and look straight ahead. Try not to move while the test is being run. The electrocardiogram will then print a reading. From there calculate and compare the findings to table 28.1, page 376 in the laboratory manual.

In the lab experiment, there were four things to find from the electrocardiogram. Before starting to calculate the test decide which lead you will be using: I or II. The first test being Beats per minute. The way to find the beats per minute was to calculate the resting heart rate by counting how many millimeters occur between two peaks (such as R to R) (Eric, 2011). After calculating the resting heart rate, then times that by 0.04 seconds/mm. This will give a calculation of second/beats. From that take sixty seconds/minutes and divide by seconds/beats. This will give the calculations of beats/minutes.

The next interval to be found was PR interval the way to calculate that is to begin at the P wave and end at the beginning of the QRS wave. Count how many boxes were in between those two and multiply by 0.04 again. After that calculation there was the QRS complex here start at the first deflection of the Q wave and ends when the S wave returns to the baseline. Again count the boxes because they represent millimeters and times by 0.04. Last you will calculate the QT interval. This interval is determined with the beginning of the Q wave to the end of the T wave (Eric, 2011). Same as the above, count the boxes that your intervals lie in and times by 0.04. After all calculations are done compare the numbers given on page 376 table 28.1.

Results

In the chart above, there are five rows each row concerning different tests. The first row talks about Beats per minute; in that row, it asks what my beats per minute was, gives if it is over a hundred, then it's Tachycardia, and if it is below sixty it is bradycardia, and then asks if it was normal or not. My beats per minute were a hundred and fifty, so it is considered Tachycardia.

The next row shows PR interval; mine was .12 but the normal is 0.16-0.18 sec so no, my PR interval is not in the norm.

Following that is the QRS complex it consisted of mine being .08 which was normal for a QRS complex.

The last test was the QT interval; again my numbers fell short. Mine was 0.2 which is lower than the norm.

The table above can also be found in Seeley’s Anatomy and Physiology laboratory manual on page 376.

Discussion

Now that the experiment has been tested, the results are in there comes the analysis part of the process. After I had determined my calculation I saw where my beats per minute were over a hundred; this consider me to be Tachycardia. Tachycardia refers to an abnormally fast resting heart rate. When examining what Tachycardia was and how it can be affected made me see that different scenarios will affect the beats per minute. Anxiety, caffeine, stress can all cause someone to have such a rapid heartbeat. I remember from when taking the echocardiogram that I was stressed about school, had a red bull that morning which led me to believe that it had an effect on the way my results were.

The next test was PR interval. Again, I was not in the norm, mine was .12 meaning it was lower than the normal. This could mean I have a partial AV heart block. With that said I am not too worried about it because of what was stated earlier. I was stressed, had more caffeine than on a normal day.

QRS complex was next. I was in the norm for that test with 0.08 seconds.

The last test was the QT interval where again I was lower than the normal, coming out with a 0.2 second rate. As I did research on the QT interval I saw where studies have shown QT interval can be passed along through the genes (). This would make sense in my cause because my father had serious heart issues. I passed one out of the four test which could mean that I have blockage in different places but it can also mean there were minor interferences with the test. For example; the science building at Reinhardt University is under construction so the table could have vibrated during the test or because I was standing up I moved. All the little things can and will have an effect on the test.

To make the test more efficient, I think you should take the test lying down. Also have more leads placed around the body. It could make the test more accurate. From my observation of my hypothesis; if there was different confliction from outside sources then it can affect the reading of the electrocardiogram; I show the hypothesis to be true. Reason why I find it to be true because out of the four test different outside source such as: caffeine, stress, and construction all affected the readings.

Overall the test did its purpose it should how to read an electrocardiogram and calculate the heart rate.

Conclusion

In conclusion, this laboratory experiment aimed to demonstrate the function of an electrocardiogram and the calculation of heart rate. The results showed that external factors such as stress, caffeine intake, and environmental vibrations can influence the readings of the electrocardiogram and the associated parameters.

Despite not falling within the normal range for some of the parameters, it is essential to consider individual variability and potential interferences when interpreting the results. Tachycardia, observed in the beats per minute, can be attributed to factors like stress and caffeine consumption. The PR interval being lower than the normal range may indicate a partial AV heart block, but this should be further investigated with clinical assessments.

The QRS complex was within the normal range, suggesting normal ventricular depolarization. However, the QT interval was shorter than the normal range, which could be influenced by genetic factors. It is essential to understand that these findings provide valuable insights but should be considered alongside a comprehensive clinical evaluation.

To enhance the accuracy of future electrocardiogram tests, conducting the test in a lying down position and using additional leads placed around the body may yield more precise results. Overall, this experiment successfully demonstrated how to read an electrocardiogram and calculate heart rate while highlighting the potential impact of external variables on the readings.

Recommendations

Based on the findings and observations in this experiment, the following recommendations are suggested:

1. Conduct electrocardiogram tests in a lying down position to minimize the influence of body movements.
2. Consider using additional leads placed around the body to improve the accuracy of the readings.
3. Be mindful of external factors such as stress, caffeine consumption, and environmental vibrations that can affect heart rate measurements and ECG parameters.
4. Further investigate any abnormal ECG findings with comprehensive clinical assessments to ensure accurate diagnosis and interpretation.

Works Cited

• Eric , Wise. "Electrical Conductivity of the Heart." 9. New York: McGraw-Hill, 2011. 376-377. Print.
• Goldenberg, L. (2006, ). Medscape Today . QT Interval: How to Measure It and What Is "Normal". Retrieved February 18, 2013, from http://www.medscape.com/viewarticle/525633