Sense ECG on ankle

[LauraBF]

Hi all, random q but has anyone successfully managed to get the ECG to work on their ankle? Mine is continually saying inconclusive. 

[TommyIzzo]

It's not designed to be worn on your ankle?

[LauraBF]

Hi Tommy, I know it's not designed to be but have always used it on my ankle without problem. It's just the ECG that I'm struggling with and not sure if it's just never going to work, or I'm doing something wrong 😊

[SunsetRunner]

@LauraBF - The ECG feature was specifically designed to be used when the device is on the wrist. I’ve worn my Sense on my ankle when using recumbent exercise machines. It captures steps well but I have noticed that it skews the heart rate readings. I would imagine that is why your readings are inconclusive. You need to use it in the way it was designed to be used. 

[SunsetRunner]

Honest question: when you measure your ECG I understand you need to use two fingers ah the opposite sides of the watch to make the measurement. I'm not sure if the optical sensor is in use during this measurement. So why should I wear the Sense on my ankle and use a very innaturale position to perform the measurement?

[LauraBF]

Thanks all. I don't have wrists (or arms) so the option of wearing it as intended isn't really one I can take. I've always had oxygen sats etc taken from my feet which is why I thought the sense would also work. I use my toes like people use fingers so put them on the corners of the device, I'm just not certain what it is that is stopping it from working (mechanically/physically rather than that it's not designed to work that way) 😊

[SunsetRunner]

Thanks @LauraBF for the details. Yes, it makes a lot of sense. Maybe some of Fitbit mods can explain better the technicalities. Have a good day!

[t.parker]

@LauraBF that's interesting. I don't think Fitbit ever tested such a use-case. In theory, electrical impulses should be detectable from almost anywhere on your body, however, the technology used in the smartwatches is very simplified and it may not account for any distortion due to placement.

You may try to see whether any other watch can handle ECG measured from toes but I kind of doubt any brand ever tested such case. For standard 12-lead ECG it's necessary to document any displacement of leads as signal may get distorted and it has to be taken into account during analysis (you can't attach electrodes just anywhere). My bet is that this is the case with Sense ECG. The signal isn't what it expects and is unable to interpret it correctly due to capturing from different location on your body.

[LauraBF]

Thanks so much for this, that's really useful. I don't imagine Fitbit would have tested in this way (totally understandably) so really helpful to have some context on how it works. I'll see if I can get hold of any others and see if they work. It's no biggie, everything else works fine if I use my own stats as a baseline, this would just have been interesting. Thanks again 

[t.parker]

You may check new Withings smartscale (not released yet) as it comes with 6-lead ECG feature. FDA and CE approvals are pending so they expect to release it in second half of 2022. I don't think it can take ECG just by standing on it though. It has retractable handle that person should grab during measurement (if I understand the marketing materials correctly). You may try to reach Withings and ask whether it would work for person with no arms (maybe they would scratch their head and get their developers to account for such use case). There are portable ECG devices which work with feet OR hands so the scale should be more on feet side, right? 🙂

[LauraBF]

Great tip, I'll check it out - thanks so much

[SunsetRunner]

Hi @LauraBF - In addition to my Fitbit devices, I also have an Apple Watch. (I just love gadgets!). I placed my Apple Watch at my ankle and started the ECG but could not get a reading. The message was - “Your ECG couldn’t be checked for A-Fib due to the quality of the recording.” I was hoping to have better news for you. .

[LauraBF · Accepted solution]

Ah thanks Carol, that's really kind of you. I suspect this is one I'm not going to get success with but everything else about the sense is good, so no complaints from me!! 

[Avendesora]

https://ecgwaves.com/topic/ekg-ecg-leads-electrodes-systems-limb-chest-precordial/   has a good explanation when you scroll down to Anatomical Planes.  The short of it is, ECGs, even normal, non-watch ones, use the arms and the left leg to create an electrical triangle in order to look at the path of electricity through the heart. With a normal ECG, they usually attach the limb electrodes to the torso to minimize the interference of other muscles in the reading (artifact). (Fancy 12-leads done in hospitals & ambulances will use the limbs, but you have to hold very still, and the right leg is "ground") I would imagine that the more significant mass of muscle from ankle to ankle would have enough muscle that you would have to be actively using in order to get your toes onto the bevel of the watch, that there would be significant artifact from all of that, and the heart is not in the direct path between your legs and would not capture well as the electricity passed between legs, so this won't work for you.  The watch is designed to read "Lead I" which is arm-to-arm across the heart.  I know this was asked 7 months ago, so hopefully you have found a chest band ecg that will work.