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Review of Normal ECG

by Joseph Alpert, MD

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    Learning Material 3
    • PDF
      Slides ECG of Myocardial Infarction.pdf
    • PDF
      Reference List Electrocardiogram (ECG) Interpretation.pdf
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    Transcript

    00:01 Hello, I'm Joseph Alpert.

    00:03 And in this talk, we are going to go over the EKG changes that occur with myocardial infarction.

    00:10 This is one of the most important uses for the electrocardiogram.

    00:13 Early recognition of myocardial infarction enables effective therapy for example; reopening a blocked coronary artery to occur which markedly improves the survivability of the patient.

    00:26 So again, let's just have a little review.

    00:29 Remember that the electrocardiogram shows the electrical depolarization of the heart.

    00:35 It's a simple, cheap, easy task often done in offices and hospitals everywhere.

    00:40 It's almost always the first cardiac test that's done.

    00:44 It's accurate for ischemia and acute myocardial infarction; that is a heart attack.

    00:49 It's also quite accurate on ventricular hypertrophy; that is enlargement of the ventricle muscle and also for arrhythmias.

    00:57 And remember, there are many nonspecific and non-diagnostic patterns which is why one has to practice a lot to recognize when something on the electrocardiogram doesn't mean anything.

    01:07 An acute myocardial infarction is a heart attack.

    01:10 It causes changes on the electrocardiogram in the T waves, in the ST segment and with the development of Q waves.

    01:19 Q waves that were not present in the normal ECG that developed during a myocardial infarct represent literally holes in the heart.

    01:27 That is electrical holes where there's no viable myocardial cells left. Remember this diagram? This is the normal electrocardiographic complex.

    01:38 Notice in yellow, the P wave, usually three little boxes are less in duration and then a - then a short segment between the P wave and the QRS.

    01:47 The entire yellow and orange section is referred to as the PR segment on the electrocardiogram.

    01:53 In gray, the QRS complex; that's ventricular depolarization.

    01:58 Then we have an ST segment that's usually flat, followed by a T wave which is the repolarization wave of the heart as it resets itself for the next beat.

    02:07 And the U wave sometimes occurs very often in patients with low blood potassium.

    02:13 Here is a normal sinus rhythm. Notice, we've talked about this in earlier slides and in earlier lectures.

    02:21 The P wave comes just before the QRS and it is less than five little boxes from the beginning of the P wave to the beginning of the QRS.

    02:31 And these are normal ECG complexes, nice narrow QRS.

    02:35 And you've seen this normal ECG before.

    02:40 This is somebody with nice, normal progression of the R waves across the precordium from almost a tiny R wave in lead V1 to a dominant R wave in V4, 5 and 6 as it goes over the left ventricle.

    02:55 And also, the axis is normal with the maximum R wave in lead II.

    03:00 And the T waves are all up right, it's a nice, normal ECG.


    About the Lecture

    The lecture Review of Normal ECG by Joseph Alpert, MD is from the course Electrocardiogram (ECG) Interpretation.


    Included Quiz Questions

    1. T wave
    2. U wave
    3. QRS complex
    4. ST segment
    5. Q wave
    1. P wave → PR segment → QRS complex → ST segment → T wave
    2. QRS complex → P wave → PR segment → ST segment → T wave
    3. T wave → TR segment → QRS complex → SP segment → U wave
    4. P wave → PR segment → QRS complex → U wave → T wave
    5. P wave → PR segment → T wave → U wave → QRS segment

    Author of lecture Review of Normal ECG

     Joseph Alpert, MD

    Joseph Alpert, MD


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