MD & DO 12-lead EKG

[1stYearGunner]

I'm trying to understand the time frame of a regular 12-lead ECG.
Please look at the image I posted.

Does I, II, III, aVR, aVF, aVL, V1 to V6 represent the same "heart beats"?

I was told in class that all vertically aligned QRS complexes represent the same heart beats.

If that is true, then since we have a longer V1 on the bottom, does that mean all the leads were not taken simultaneously?

I'm lost please ELI5 this to me.

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[Gurby]

Leads were all taken simultaneously, just sometimes getting a longer snapshot of the same lead can help figure out a tricky rhythm or whatever. Maybe this image will make it clearer. Notice the irregularity, but QRS's all align vertically:

 

[Rekt]

I'm trying to understand the time frame of a regular 12-lead ECG.
Please look at the image I posted.

Does I, II, III, aVR, aVF, aVL, V1 to V6 represent the same "heart beats"?

I was told in class that all vertically aligned QRS complexes represent the same heart beats.

If that is true, then since we have a longer V1 on the bottom, does that mean all the leads were not taken simultaneously?

I'm lost please ELI5 this to me.

Yes, they all represent the same "heart beat". There's two V1s in this particular picture because the V1 at the bottom is what we call the rhythm strip, it lets us get a better look to see if there are any arrhythmias. I recommend reading Dubin, it's a very easy read and will set you up nicely with EKGs and you can move on to more advanced books. It can be read in a couple of days.

 

[AnatomyGrey12]

The bottom is a full 10 second strip, while the top is each individual lead for 2.5 seconds I believe. I found the website Geeky Medics to be very helpful for ECGs, Dubin is also a good resource.

 

[1stYearGunner]

So the machine does this:
For 2.5 seconds: reads I, II, III
Immediately after, it records for 2.5 sec : aVR, L, F
Immediately after, it records for 2.5 sec: V1 2 3
Immediately after, it records for 2.5 sec : V4 5 6
And you can also tell the machine to record any other lead for 10 seconds simultaneously.
So, at any time, the machine is recording only recording 4 leads.

 

[AnatomyGrey12]

No all leads are recorded simultaneously.... you get a different wave for each lead based on the electronegativity. It will also spit out a full 10 second strip to get a clear picture of heart rhythm.

 

[FiremedicMike]

It depends on the machine.

 

[frosted2]

No. The "longer" strip showing V1 is a variation that you can program into the EKG machine. Something that threw me off when I first started interpreting EKGs (going to a thousand different clinical sites...) is that the format can change from hospital to hospital... always double check! For example, in the original EKG you posted, not only does it show I, II, III, aVR, aVL, aVF, V1-V6, but it also shows a full 10 seconds of V1, II and V5. OTOH, in the ambulance, ours only prints off a strip similar to what I posted below.

Are you simply looking for the timing? If so, a 12 lead (the screen shot of the 12 lead you posted I put below with exactly what you need to look for) is a 10 second strip. That is the activity of the heart that is recorded in 10 seconds from 12 different angles.

I hope that helped!!

 

[1stYearGunner]

I don't see how all 12 leads record the same 4 heartbeats. That would not make sense with the fact that the long strip still aligns with all QRS. Each lead only records for 2.5 seconds except for the long strips that record for 10 seconds.

If we all agree with the fact that, in my original picture, V1 in its long form records 14 different heartbeats, then I, aVR, v1 and v4 should each record about 3.5 (14 heart beats/4leads) different heart beats.

 

[Gurby]

I don't see how all 12 leads record the same 4 heartbeats.

That's because they don't...

If we all agree with the fact that, in my original picture, V1 in its long form records 14 different heartbeats, then I, aVR, v1 and v4 should each record about 3.5 (14 heart beats/4leads) different heart beats.

That's correct...

 

[1stYearGunner]

That's because they don't...



That's correct...

Ok! Glad we cleared that up. Thanks