Reading ECGs – Cardiac Dysrhythmia

by Joseph Alpert, MD

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    00:00 So, again, let’s talk a little bit about the diagnosis by the electrocardiogram. Remember the first thing is, you get a Gestalt, you get an image, you then do a very very careful analysis of the various intervals - Are they appropriate? Is the heart rate appropriate? Is the electrical activity and the heart moving in the right direction? Do you see any abnormality such as ST elevation, we talked about the ST elevation, myocardial infarction? Are there abnormalities in the T wave? You can also diagnose increased heart volume because the QRS has become very large. There's a whole variety of diagnoses and they help the clinician.

    00:43 The electrocardiogram is most helpful when you know something about the patient. You can then have taken the patient’s history, the physical exam and you look at the electrocardiogram and you bring those together in making a diagnosis. Again, remember, that the computer diagnosis is correct about 80% of the time, but wrong 20% of the time and particularly wrong when it comes to diagnosing arrhythmias. Very briefly, let’s talk a little bit about treatment. Treatment is very complex. There are a variety of medications, so called anti-arrhythmic drugs which help to control all arrhythmias. You can control atrial arrhythmias, you can control ventricular arrhythmias. However, these are medications that are associated with the most side effects, the most adverse side effects of any of the cardiac medications we use. Remember, I mentioned Statin drugs - very well tolerated, very few adverse events.

    01:38 Anti-arrhythmic drugs are the opposite, there's a lot of side effects in part because they affect electrical activity. When they affect the electrical activity in the heart, they can also affect the electrical activity in the brain and in the peripheral nervous system.

    01:51 So, you may have side effects relating to the fact that they are blocking electrical activity in areas where you would prefer that they not. Of course, pacemakers, I already mentioned a number of times, that’s when the heartbeat is missing in a particular area either atria of the ventricle or both and we put in a wire and a little box under the skin that stimulates the heart so that there's a normal rate. And actually, there's newer pacemakers that actually can tell when you start to exercise and they increase the heart rate. Sometimes we use pacemakers to help control arrhythmias and then of course, there is the so called ablation where the cardiac electrophysiologist go in with catheters and they burn out areas that are causing arrhythmias and sometimes they take several of these treatments and often in combination with drugs, we can obliterate and knock out the arrhythmia so that the patient doesn’t have repeated visits to the emergency room because of that.

    02:52 So, in summary, I think I've made this point a number of times, we have to overread the computer reading very carefully, we have to look at the Gestalt, the overall picture, the pattern recognition and we have to look carefully that each of the leads has been done appropriately, that the direction of the electrical impulse in the heart, that the rate, that all of the waves are in the normal position and if they're not, we need to interpret how they're abnormal. Remember that an experienced person needs to overread the electrocardiogram and we need to interpret the electrocardiogram often in the setting of the clinical situation that the patient is having. So, the patient with chest pain, we’re going to be looking for changes that suggest ischemia in the heart. In a patient who has shortness of breath, we're going to be looking for patterns that suggest hypertrophy of the heart and so forth. The more clinical information you have, the more intelligently you will read the electrocardiogram. Even minor changes on the electrocardiogram can be important, particularly, for example, in a patient with chest pain. Small changes in the… the space between the QRS and the T wave can suggest ischemia in the heart and that’s what we look for, by the way, on a stress test when we exercise the patient.

    04:14 And finally, to reiterate one more time for you, the computer EKG reading is helpful, but it’s only accurate about 80% of the time. And again, how do you learn to read a cardiogram? The same way you learn to play a musical instrument or play tennis - practice, practice, practice. So, with this final view of New York city from the Empire State Building, we'll leave cardiac arrhythmias. It’s an area that’s very interesting, very common in clinical practice, requiring a lot of experience to deal with and its something, again, that’s become so complex that we actually have special cardiologists that do nothing else, but deal with arrhythmias every day.

    About the Lecture

    The lecture Reading ECGs – Cardiac Dysrhythmia by Joseph Alpert, MD is from the course Cardiac Diseases.

    Included Quiz Questions

    1. A 67-year-old woman with sinus tachycardia
    2. A 58-year-old man with a heart transplant
    3. Siamese twins
    4. An individual who is having an ECG recorded while holding hands with another person
    5. A 78-year-old man with cardioembolic stroke
    1. Left and right atria
    2. Left ventricle
    3. Right ventricle
    4. Left and right ventricles
    5. Right atrium and ventricle
    1. Left and right ventricles
    2. Left and right atria
    3. Right atrium and ventricle
    4. Left atrium and ventricle
    5. All four chambers of the heart
    1. Pacemaker
    2. Beta blockers
    3. Potassium-sparing diuretics
    4. Alcohol septal ablation
    5. Heart transplantation
    1. Myocardial infarction
    2. Sinus arrest
    3. Sinus pause
    4. Premature atrial contraction
    5. Sinus tachycardia
    1. Interference with neural electrical activity
    2. Altered electrolyte balance and osmotic misbalance
    3. Poor tolerance by gastrointestinal tract
    4. Poor resistance to stomach acid
    5. First pass effect

    Author of lecture Reading ECGs – Cardiac Dysrhythmia

     Joseph Alpert, MD

    Joseph Alpert, MD

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    more pathology with treatments.
    By jaime a. on 28. February 2023 for Reading ECGs – Cardiac Dysrhythmia

    this lectures are too basic, too much "we should do this and and we should do that" basically is what i keep hearing in these lectures. I not in high school anymore !! I need substance and more pathology and treatment not 1+1= ?