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Any medical students keen to learn detailed interpretation of the ECG?

Good evening ("Hi" in modern lingo!), With all of us tied in at home with CoV-SARS2, I felt that I could help students with getting v good at reading ECGs - I won the cardiology prize as a medical student. If people show an interest, I can put up some ECGs and go through them with you! Any "punters" ?

Reply 1

Socrates08

Original post by macpatgh-Sheldon

I’m not a medical student yet as I start in September (hopefully) but we had to learn ECG traces for a level biology so I’d deffo be up for gaining some more knowledge

Reply 2

macpatgh-Sheldon

Ok @Socrates08, you are a midnight oil burner looks like - thank you for showing an interest. I am an "early to bed, early to rise" guy, but just to whet your appetite, let me put up something before bed to whet your appetite!

Since you are just starting off with ECGs, let us take a simple example:-

You know that the QRS complex is generated by ventricular depolarization, and maybe you know that electrical activity travelling towards the relevant electrode shows a positive deflection and activity going away from the electrode produces a negative deflection.

You also know that the left ventricle has a much thicker muscular wall than the right ventricle. Now, I have to give you some info and then ask you to use that info and simple logic [to an extent] to work out answers.

When a patient suffers an MI (myocardial infarction - death of part of the cardiac muscle tissue due to sudden lack of oxygen following the formation of a clot in a coronary artery), he/she is likely to show some ECG changes [though not always].

Why might you get [actually a few days after the initial episode] deep Q waves [in some leads] in MI? [clue: the Q wave is the first negative deflexion before the positive one, which is the R wave].

Have a shot: other nocturnal creatures are also welcome to try - I shall be giving tips when my eyelids are not drooping.

M

Reply 3

macpatgh-Sheldon

Clue no. 1 for the early birds: Will there be any electrical activity originating from the infarcted (dead) myocardium?

Clue no. 2 in the morning!

Reply 4

Socrates08

Original post by macpatgh-Sheldon

Clue no. 1 for the early birds: Will there be any electrical activity originating from the infarcted (dead) myocardium?

Clue no. 2 in the morning!

Okay let me think here I’ve actually got to use my brain whilst schools are closed 😂
I believe it’s called a pathological Q wave which is abnormality in the amplitude or length of time taken
I believe I’m right in saying there would be no
electrical activity from that point in the heart
Taking a stab in the dark here - if the area of affected heart had no electrical activity the surrounding areas would need a greater electrical activity to keep the heart functioning successfully thus a greater amplitude?? This may take longer than standard ventricular systole due to having to find a way around the scar tissue causing a wider Q wave?
I am really not knowledgable on this haha

Reply 5

macpatgh-Sheldon

Ok no probs - good attempt though not quite right (I would not expect an A level student to know this, but then after all you are a Greek scholar! :colondollar:

[related to Archimedes?]).

What actually happens is that, as you correctly say, the infarcted myocardium, which in normality [prior to the "heart attack"] was sending electrical activity towards a facing electrode, now has no electrical activity, constituting what is referred to as an "electrical window". So now any electrode "facing" the infarct will "see" electrical activity from the opposite wall of the relevant ventricle, which is oc moving away from the electrode, and therefore produces a negative deflection, namely the Q wave.

Good attempt and your explanation for the duration of the Q wave is just about right.

I will try to put up another Q soon as this has got you thinking, although a little more interest would be useful from others, particularly as a number of students are doing exams soon, albeit online from home.

M

(edited 4 years ago)

Reply 6

Socrates08

Original post by macpatgh-Sheldon

Ok no probs - good attempt though not quite right (I would not expect an A level student to know this, but then after all you are a Greek scholar! :colondollar:

[related to Archimedes?]).

What actually happens is that, as you correctly say, the infarcted myocardium, which in normality [prior to the "heart attack"] was sending electrical activity towards a facing electrode, now has no electrical activity. So now any electrode "facing" the infarct will "see" electrical activity from the opposite wall of the relevant ventricle, which is oc moving away from the electrode, and therefore produces a negative deflection, namely the Q wave.

Good attempt and your explanation for the duration of the Q wave is just about right.

I will try to put up another Q soon as this has got you thinking, although a little more interest would be useful from others, particularly as a number of students are doing exams soon, albeit online from home.

M

Ahhh that was my next guess :wink:

Many thanks for the explanation it’s really nice of you to help up and coming medical students by passing along your knowledge :smile:

Cheers! And be safe!

Original post by macpatgh-Sheldon

Ok no probs - good attempt though not quite right (I would not expect an A level student to know this, but then after all you are a Greek scholar! :colondollar:

[related to Archimedes?]).

What actually happens is that, as you correctly say, the infarcted myocardium, which in normality [prior to the "heart attack"] was sending electrical activity towards a facing electrode, now has no electrical activity. So now any electrode "facing" the infarct will "see" electrical activity from the opposite wall of the relevant ventricle, which is oc moving away from the electrode, and therefore produces a negative deflection, namely the Q wave.

Good attempt and your explanation for the duration of the Q wave is just about right.

I will try to put up another Q soon as this has got you thinking, although a little more interest would be useful from others, particularly as a number of students are doing exams soon, albeit online from home.

M

Feel like you could have let someone else have a guess here :wink:

The other thread about clinical questions generated a fair few contributors.

Are we going to be getting the high resolution electrodes out for the next one? :wink:

Reply 9

macpatgh-Sheldon

@nexttime

You have a point there, sir! I am hoping to put up a [just slightly] more challenging one as the follow-up [maybe some medics will respond instead of just A level students], AND WILL DEFINITELY wait for more responses as per your suggestion. As for the other thread, actually that was what gave me this idea (thank you, HumblyBumbly [this was the OP on that one I think])!.

It is apparent from your numerous posts that you are a practising doctor - you must be inundated with the COVID-19 issue rn. Be safe!

M

Reply 10

macpatgh-Sheldon

Any takers to discuss [electrophysiological] "matters of the heart" further? Including @Socrates08 :

Hi boys & girls,

Please look a this electrocardiogram from a 62 year old woman who presented with a short history of palpitations and
a) outline three abnormal findings on it together with your explanation/logic.
b) what Q you might ask her?

(Sorry, there is no rhythm strip on this ECG).