IEC 60601-2-25 ECG 4 electrodes and derived leads

[Standardize]

In principle,
We can use 4 electrodes LA, RA, LL, RL and conjure up 6 waveforms or LEADS.
2 LEADS would be actually measured and the remaining 4 LEADS would be derived from the 2 measured leads.
My question is does the standard explicitly mention that all LEADS need to be acquired in analog domain?
I mean is it valid to acquired just Lead I and Lead II in analog domain and derive the remaining in digital domain and still pass the standard?

 

[eldercosta]

Hello.

Do you want to have six leads from I and II? I'm affraid not. If you want only III, than it is OK as it is "embedded" in I and II but not aVR/aVL/aVF.

About the second part, I have no access to the standard so I cannot answer. What exactly do you want to achieve?

 

[Standardize]

Hi,
Thanks for your reply, AFAIK,

The Lead calculations are as under

LEAD III = LL - RA - LA = LEAD II - LEAD I
aVR = RA - (LA + LL) / 2 = - (LEAD I + LEAD II) / 2
aVL = LA - (RA +LL) / 2 = LEAD I - LEAD II / 2
aVF = LL - (RA + LA) / 2 = LEAD II - LEAD I /2

Correct me if I'm wrong.

 

[eldercosta]

Hello, you're right. I misinterpreted your first post. That along with fatigue (note to myself, do not post when tired) made me miss the simple math you are posted above (and that I have used in the past).

So, I agree with you, I see no reason why you could not derive lead III from I and II. I have used the same strategy aaeons ago for a 12-lead electrocardiograph, a 7-lead monitor. I have also seen it in some other products.

That said, is is advisable to sample at the highest resolution you can, preferably 2.5uV/ADU or better if you want to keep the quantization error low by design (assuming the standard requires 5uV quantization).

And, of course, as many other things, take advices in forums with a grain of salt.

 

[shrikanth]

Pass select clauses of the standard, yes, but why attempt to pass all of it if is not a diagnostic device?

IEC 60601-2-25 covers several aspects of diagnostic ECG requirements and with 2-51 being merged into it, ECG measurements become a part of it.

With just 4 electrodes, several clinical requirements of diagnostic ECGs are met.. say for example, anterior myocardial infarction could simply not be detected without pre-cordial lead information. Likewise, detection of left bundle branch block in the absence of chest leads would be less sensitive.

So it may be important to position such devices correctly, from a regulatory standpoint as 'non-diagnostic', but for "triaging" use!