Electrocardiography (ECG) (Nursing)

by Jasmine Clark

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    00:01 The way we measure this is by electrocardiography.

    00:06 An electrocardiograph can detect the electrical currents that are generated by the heart.

    00:14 An electrocardiogram is the graphing record of that electrical activity.

    00:21 It's important to note or understand that the peaks and the electrocardiogram, the peaks and valleys do not correspond to actual membrane potentials because it's going to be a culmination of all of the action potentials that are happening over the entire heart.

    00:42 In this process, electrodes are placed at various points on the body in order to measure the voltage differences.

    00:51 So how does this work? The main features of an electrocardiogram include a P wave which is going to correspond to the depolarization of the SA node and the atria.

    01:06 From there, we have the P to R interval which is the beginning of atrial excitation all the way to the beginning of ventricular excitation.

    01:18 We also have the QRS complex.

    01:22 This is going to correspond to ventricular depolarization as well as atrial repolarization.

    01:32 Also, we have the QT interval which is the beginning of ventricular depolarization through the ventricular repolarization.

    01:44 the ST segment of the electrocardiogram is going to be the entire ventricular myocardium being depolarized.

    01:53 And finally, we have our T waves which corresponds to ventricular repolarization.

    02:03 In a normal ECG trace, when we have sinus rhythm, you notice that for about a second, you have a P wave followed by your to QRS peak followed by the T wave and in a second you usually can get about two of these occurring.

    02:24 Sometimes when you do a trace you'll notice that there is some abnormalities.

    02:29 For example if the AV node fails to conduct some SA node impulses, what you'll find is that you have multiple P waves per QRS wave.

    02:43 This lets you know that there's some type of blockage and usually in this circumstance, you see two P waves per QRS wave instead of one P wave per QRS wave.

    02:58 Sometimes in ventricular fibrillation, we can see just a disorganized tracing where are the electrical activity is just kind of all over the place.

    03:09 This is because action potentials are occurring randomly throughout the ventricle.

    03:14 This is a grossly abnormal ECG deflection and this is what you can see sometimes in acute heart attacks or after an electrical shock.

    About the Lecture

    The lecture Electrocardiography (ECG) (Nursing) by Jasmine Clark is from the course Cardiovascular System: Heart – Physiology (Nursing).

    Included Quiz Questions

    1. P wave
    2. QRS complex
    3. T wave
    4. P-R interval
    1. P-R interval
    2. P wave
    3. QRS complex
    4. Q-T interval
    1. QRS complex
    2. P wave
    3. P-R interval
    4. T wave
    1. Q-T interval
    2. QRS complex
    3. S-T segment
    4. T wave
    1. S-T segment
    2. Q-T interval
    3. P wave
    4. P-R interval
    1. T wave
    2. P wave
    3. S-T segment
    4. P-R interval

    Author of lecture Electrocardiography (ECG) (Nursing)

     Jasmine Clark

    Jasmine Clark

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