Electrocardiogram (ECG) Basics [Micro Lecture]

In today’s micro lecture, APC Hon. Snr. Lecturer Sam Willis talks about the basics of the electrocardiogram (ECG), which is a medical test that detects heart problems by measuring the electrical activity generated by the heart as it contracts.

In today’s micro lecture we’re going to talk about the basics of ECG

Now you are all reading your different things, you’re all learning ECG’s at a different pace and you’re all pick things up slightly differently to each other and that’s fantastic. So, we’re just going to go over the basics for those of you who may be struggling with the basics.

If you don’t have a basic understanding of of an ECG and what the different lines mean, you’re going to struggle to scaffold on top of it.

Okay? So, let’s start by going through this wave form.

Now, for those of you who have never seen this image before, it looks a bit complex. It’s like a different language altogether, but start by familiarizing yourself with it. Try not to be overwhelmed by all the different things that are on here, and what you notice is there’s two axes.

There is a time axes and there’s a voltage axes. So what this means is every time you have you see a dig, this thing here is called a baseline, or the ISO electric line. Every time you see a movement away from it. Now, anything that goes above the isoelectric line is a positive way form, anything below it is a negative way form.

So, the bigger this positive deflection is, the more voltage there is. The bigger the P wave is, for example, the more energy there is in that P wave.

So, let’s go through the basics P, Q, R, S and T. So, they just the letters of the alphabet. Think back to the physiology of the heart. When the atria contracts that will show you on the ECG a P wave. So when I look at this, I see there’s an atria contract and so if this is the top part of the heart, this is the bottom part, atria ventricles, atria ventricles, atria ventricles. So when the atria contracts, you’ve got a P wave on the ECG. Likewise, when the ventricles contract at the bottom, you get the Q, A and the S. So the P and the QRS, PQRS, PQRS.

Then of course you get this T wave. So when the heart is relaxing, you’re getting these T wave on here.

So let’s go through that again. Atria contracts, you get a P wave. QRS contracts, QRS ventricles, atria ventricles, atria ventricles.

Now, it is a bit more technical than that because there’s times involved and it might not be in the right order, but what I’m trying to get you guys to understand is on an ECG like this, whenever you see a P wave like that, it means that the ventricles are contracting. It actually means atrial depolarization.

But I don’t want to put too many words in here to confuse you. Likewise, the QRS means ventriculating polarization, and T wave means complete ventricular re-polarization.

That’s all we’re going to talk about for now. I hope you’ve enjoyed this session, my name is Sam Willis (APC Hon. Snr. Lecturer) and I look forward to talking to you again soon.

Electrocardiogram – ECG Basics

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