The purpose of this experiment was to become familiar with the electrocardiograph to help us determine the electrical activity of the heart. As well as, to observe how exercise and different body positions(conditions) can affect the activity of the heart.
Introduction Trained professionals can look at the EKG tracing and determine if the heart is normal or if the heart is abnormal. “An ECG records the electrical activity of the heart. The heart produces tiny electrical impulses which spread through the heart muscle to make the heart contract” (Kenny, 2015). There are two different types of cells. Autorhythmic (electrical) cell begins electrical activity and triggers contractile fiber, and contractile (myocardial) generates force to pump blood.
With each heartbeat the cardiac system starts with the pacemaker (called the SA node) that conducts electricity. The electrical current travels from the SA node and signals the atria to contract. Then into the Antrioventucular node, which signals the ventricles. Eventually, into bundle of his, left and right bundle branches, and lastly Purkinje fibers. Purkinje fibers then stimulate the contractile fibers.
In addition, the EKG (electrocardiogram) illustrates series of waves and flat lines (isoelectric) usually seen on computer monitors. Waves represent electrical activity through the heart and the physical events that take place in the heart, systole (contaction occurs and blood pumps into arteries) and diastole (blood pumps into heart). In addition, a normal heart has three waves illustrated on the EKG. One, P Wave represents atrial depolarization. Second, QRS Complex represents rapid ventricular depolarization. Lastly, T Wave represents ventricular repolarization.
Intervals and segments can be seen too in the EKG. Intervals include a wave and a flat line and the segment are just flat lines. After all the EKG is essential to determine if our heart is healthy. Materials • BIOPAC Electrode Lead set (SS2L) • BIOPAC Disposable electrodes (EL503) 3 electrodes per subject • BIOPAC Electrode Gel (GEL1) and Abrasive Pad (ELPAD) • Skin cleanser or alcohol prep • Mat, cot or lab table and pillow for Supine position • BIOPAC Student Lab System: BSL 4 software or MP36
Methods First, all equipment was plug in correctly, for instance electrode lead Set (SS2L) plugged in CH1. Second, the Biopac unit was turn on. Thirdly, Skin was cleaned and abrade. Fourth, three electrodes were attached on the subject. Two were placed in the medial surface of each leg, and the last electrode was places on the right anterior forearm at the wrist. Fifth, the Electrode Lead Set was clipped to the electrodes depending on the color code.
For example, the right forearm was clipped with white lead, right leg to black led, and left leg to red lead. Sixth, the subject got in a supine position and relaxes. Seven, BIOPAC Student Lab program was started. Eight, “L05- Electrocardiography (ECG) was chosen. Ten, calibration was made to make sure everything was working properly. Eleven, the subject was laying down (supine position) and we recorded for 20 seconds. Twelve, the subject got up quickly into seated position and data was recorder.
Thirteen, subject inhale and exhale slowly. F4 was pressed at the beginning of every inhale and F5 for every exhale. Fourteen, the subject removed the electrodes wires and began to exercise for 5 minutes. Then the subject placed electrodes wire on the electrode pads and data was recorded. Lastly, the done button was clicked. Results The graphs below show how a conditions can affect the heart activity. The graphs represent heart rate, ventricular systole and diastole, components of the EKG that was determined by the Electrocardiogram. A: Heart Rate Conditions
Heart Rate (BPM)
Mean (calculations) 1 2 3 1. Supine 60.12 59.35 59.70 59.72 2. Seated 75.38 77.62 75.66 76.22 3. Start of inhale 20.44 22.33 26.77 23.18 4. Start of exhale 17.09 15.67 14.86 15.87 5. After exercise 139.21 135.74 140.19 138.40 Graph A represent how heart rate changes due to the different conditions a subject had to perform. The graph shows that the more physical activity the subject performs, the higher the heart rate will be.
B: Ventricular Systole and Diastole Condition Duration in seconds (Delta T) 1.Supine
4. After Exercise Ventricular Systole .29500 sec .18400 sec Ventricular Diastole .69400 sec .24600 sec Graph B compares the duration in seconds (Delta T) of the Ventricular Systole and Diastole. The Graph shows that after exercise the duration in seconds decrease in both conditions.
C: Components of the ECG ECG Component Normative Values Duration (Seconds) Delta T Recording Supine
Rec Supine Mean (Calc.)
Rec After Excercies One Cycle P .07 – .18 .093 .090 .091 .09 .105 QRS Complex .06 – .12 .065 .062 .054 .06 .060 T .10 – .25 .244 .241 .229 .22 .258 Intervals Duration (seconds)
P-R .12 – .20 .187 .199 .195 .19 .182 Q-T .32 – .36 .393 .402 .388 .39 .298 Segments Duration (seconds)
P-R .02 – .10 .066 .060 .082 .07 .034 Graph C compares the duration in seconds (Delta T) in the components of the ECG (intervals, segments) during supine and after exercise. The graph shows that Delta T for the supine and exercise averages where in the normative values.
Analysis and Discussion As showed from the tables above, mechanical movements impact the activity of the heart. For instance, graph A compares the heart rate at a supine position, when the subject seated, during inhalation and exhalation, and after exercise. A heart rate represents how many times a contraction is being made in the ventricles (heart beat). The average gathered from a supine body position was 59.72. Then the heart rate barely increased to 76.22 when the subject seated, and lastly after the subject exercise the heart rate increased dramatically from 138.40.
This indicates that the heart is pumping less during a supine position because the “effect of gravity on your body is reduced, allowing more blood to flow back to your heart through your veins” (Hughes, 2013). Then when the subjects seated up the heart rate didn’t increase much, because the body was still at rest. However, when subject exercise the heart rate increase, because the muscles need more oxygen to produce energy. In the other hand, inhalation (23.18) increased heart rate than exhalation (15.87).
This can be concluded, because blood going to the heart increased (increase in heart rate. As a result, the heart rate increase when the body is in intense movements or during inhalation. At the same time, Graph B show how the cardiac cycle has an influence during supine and after exercising. The cardiac cycle “is the sequence of events that occurs when the heart beats” (Baily, 2016). The cardiac cycle includes the ventricular systole and diastole. The graph indicates that diastole decreased duration from supine to post exercise – from .69400 seconds to .24600 seconds. However, the duration of systole decreased more during exercise.
There is less time between systole than diastole. Up to present time, Graph B showed us that when the body is exercising the systole and diastole will decrease duration making the cardiac cycle shorter. Equally important, Graph C shows the components of the EKG. So, the duration of intervals and segments during resting and excursive decrease. Intervals P-R decreased .193 (supine) to .182 (after exercise), and Q-T decrease from .394 to .298. This shows that after exercising, interval P-R decreases duration of ventricular depolarization. Somewhat similar as to interval Q-T, decreasing ventricular repolarization. In addition, segment P-R decreased too after exercise.
During supine position the duration was .064, and after exercise it was .034. This indicates that duration decreases after exercise making the heart beat faster. However, our subject had normal durations over all. For example, during QRS complex normative values where .06- .12, and our subject duration where .060 during supine and after exercise. We can conclude that our subject regularly exercise. This is not the same for everyone, because it depends on age, and if they exercise regularly.
As seen above, the tables indicate that the different conditions or body movement change the heart activity. For instance, after exercise the heart rate increased, systole and diastole decrease, and intervals and segment decreased. Based on the results different condition changes heart activity, but in the future we can experiment if emotions changes or affects heart activity. We can accomplish this by having a subject wired to the EKG and making them feel angry, sad, and happy. However, the EKG help us determine heart activity during the different conditions and concluded that the different conditions have an effect on the heart activity.