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I have a question about the Apple Watch's EKG/ECG feature, maybe someone can answer: I had a routine EKG last week for a pilot medical certificate. Before the

I have a question about the Apple Watch's EKG/ECG feature, maybe someone can answer: I had a routine EKG last week for a pilot medical certificate. Before the EKG, the nurse rubbed a cold gel on my skin, at the places where she then placed the EKG contacts. I'm assuming this gel was to ensure good contact. If doctors have to rub this gel before an EKG, why doesn't the Apple Watch need this, to ensure good contact?

MBCook 8y ago
I’m guessing it just relies on pressure. The watch is held against your skin by the band, your finger is held against the crown by your muscles. I guess they’ve tested it and it seems to be good enough. As EKGs go it’s a relatively basic test, is the equivalent of having a single wire. I’m very curious to see what doctors/etc. make of it once the feature is released.
monkmartinez 8y ago
You probably had a either a 12 lead or 3 lead EKG... the Watch is only a single lead. Therefore, much less is needed in terms of conductivity for the sensors to measure.
harshreality 8y ago
If you're measuring (or applying) voltage on skin, you get cleaner data if you use conductive gel, since you have less chance of a poor electrical contact between sensor and skin. If you can't use it though, you can't use it. The data may have glitches, anomalous readings, but most of it will be pretty good most of the time, or they wouldn't bother with the feature. I'm also not sure what the apple watch's sensing mechanism is. Is it reading voltage or is it measuring something else that's correlated?
- ip26 8y ago
  Also worth thinking about- the EKG is your "golden reference". You do it once, you want it to come out clean, you want it to come out right, and you may make treatment decisions based upon it. The watch is always running, can throw out large quantities of glitches & anomalous readings, and only produces an alert to seek followup.
mtw 8y ago
In the same manner that in a conventional ECG, 10 electrodes are used while this only requires you to put your finger on the crown. The data is less accurate but apparently good enough to detect 98% of AFib cases.
- GeekyBear 8y ago
  The 12 lead ECG is used for a different diagnostic purpose. The Apple Watch is positioned as a cardiac event monitor. Those are intended for extended wear and only need to take measurements between a single pair of electrodes to function. For instance, a Zio Patch is a modern version designed to be compact and unobtrusive. Here's a comparison between a Zio Patch and the old school tech of a Holter Monitor. https://www.medgadget.com/2014/01/zio-wireless-patch-may-be-better-option-than-holter-monitors-for-cardiac-arrhythmia-diagnosis.html https://www.medgadget.com/2014/01/zio-wireless-patch-may-be-... One of the tech journalists at Ziff Davis who took part in Apple's heart study ended up being dignosed with Afib by his cardiologist. He wrote about the process he went through. TLDR: The watch flagged that there was a potential problem, he was given a traditional tape on cardiac event monitor to wear for an extended period to confirm the watch data, and was then diagnosed and treated. https://www.zdnet.com/article/how-apple-watch-saved-my-life/ https://www.zdnet.com/article/how-apple-watch-saved-my-life/ For me, this was the money quote: "I've had EKGs a number of times, and there was never any indication anything was wrong."
- JshWright 8y ago
  It's not necessarily "less accurate" data (it may or may not be), there is just less of it. A conventional ECG uses those 10 electrodes to view the heart from 12 different "directions", which allows you to understand how impulses are moving throughout the heart as a whole. A watch only gets you one of those leads (Lead 1, specifically).
mikestew 8y ago
If doctors have to rub this gel before an EKG, why doesn't the Apple Watch need this, to ensure good contact? It probably varies by person, but heart monitor chest straps such as those that come with higher-end exercise watches, can benefit from the gel. However, most folks (including myself) either just slap 'em on dry, or with a little spit, and they usually work fine. But at the doctor's office "usually" probably doesn't cut it. If a little gel changes "usually" to "always", then they probably apply as a matter of course. That's my long-winded way of saying that a little gel on your wrist and finger would help (I guess; I've not seen the watch yet, nor am I a medical professional). But for the not-a-lab-or-medical-office setting, it's good enough.

MBCook 8y ago

I’m guessing it just relies on pressure. The watch is held against your skin by the band, your finger is held against the crown by your muscles. I guess they’ve tested it and it seems to be good enough. As EKGs go it’s a relatively basic test, is the equivalent of having a single wire. I’m very curious to see what doctors/etc. make of it once the feature is released.

monkmartinez 8y ago

You probably had a either a 12 lead or 3 lead EKG... the Watch is only a single lead. Therefore, much less is needed in terms of conductivity for the sensors to measure.

harshreality 8y ago

If you're measuring (or applying) voltage on skin, you get cleaner data if you use conductive gel, since you have less chance of a poor electrical contact between sensor and skin. If you can't use it though, you can't use it. The data may have glitches, anomalous readings, but most of it will be pretty good most of the time, or they wouldn't bother with the feature. I'm also not sure what the apple watch's sensing mechanism is. Is it reading voltage or is it measuring something else that's correlated?

ip26 8y ago
Also worth thinking about- the EKG is your "golden reference". You do it once, you want it to come out clean, you want it to come out right, and you may make treatment decisions based upon it. The watch is always running, can throw out large quantities of glitches & anomalous readings, and only produces an alert to seek followup.

mtw 8y ago

In the same manner that in a conventional ECG, 10 electrodes are used while this only requires you to put your finger on the crown. The data is less accurate but apparently good enough to detect 98% of AFib cases.

GeekyBear 8y ago
The 12 lead ECG is used for a different diagnostic purpose. The Apple Watch is positioned as a cardiac event monitor. Those are intended for extended wear and only need to take measurements between a single pair of electrodes to function. For instance, a Zio Patch is a modern version designed to be compact and unobtrusive. Here's a comparison between a Zio Patch and the old school tech of a Holter Monitor. https://www.medgadget.com/2014/01/zio-wireless-patch-may-be-better-option-than-holter-monitors-for-cardiac-arrhythmia-diagnosis.html https://www.medgadget.com/2014/01/zio-wireless-patch-may-be-... One of the tech journalists at Ziff Davis who took part in Apple's heart study ended up being dignosed with Afib by his cardiologist. He wrote about the process he went through. TLDR: The watch flagged that there was a potential problem, he was given a traditional tape on cardiac event monitor to wear for an extended period to confirm the watch data, and was then diagnosed and treated. https://www.zdnet.com/article/how-apple-watch-saved-my-life/ https://www.zdnet.com/article/how-apple-watch-saved-my-life/ For me, this was the money quote: "I've had EKGs a number of times, and there was never any indication anything was wrong."
JshWright 8y ago
It's not necessarily "less accurate" data (it may or may not be), there is just less of it. A conventional ECG uses those 10 electrodes to view the heart from 12 different "directions", which allows you to understand how impulses are moving throughout the heart as a whole. A watch only gets you one of those leads (Lead 1, specifically).

mikestew 8y ago

If doctors have to rub this gel before an EKG, why doesn't the Apple Watch need this, to ensure good contact? It probably varies by person, but heart monitor chest straps such as those that come with higher-end exercise watches, can benefit from the gel. However, most folks (including myself) either just slap 'em on dry, or with a little spit, and they usually work fine. But at the doctor's office "usually" probably doesn't cut it. If a little gel changes "usually" to "always", then they probably apply as a matter of course. That's my long-winded way of saying that a little gel on your wrist and finger would help (I guess; I've not seen the watch yet, nor am I a medical professional). But for the not-a-lab-or-medical-office setting, it's good enough.