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Comment by coob | Hacker News Reader

Could a smart watch detect a heart attack?

To take an ECG tracing you need at least 3 points of contact with skin around the body (a hospital ECG has 9 leads attached to the body from which the machine calculates 12 waveforms of electrical activity). A watch based mechanism would not have the capacity to do this and even a 3 lead ECG would not be considered sufficient as it would miss too many changes.

I therefore believe that a smart watch would not with any current technology be capable of detecting a heart attack.. Pulse and heart rate are simply not useful (neither sensitive or specific) criteria for detecting MI's

For further reading on the physics of an ECG hit up

http://en.m.wikipedia.org/wiki/Einthoven's_triangle

Edit: my ECG knowledge is a bit rusty- 2 points of contact is enough to produce a single waveform reading...

How, about detecting one of the side effects of a heart attack? You can then evaluate if you have a problem by any of the other symptoms. If I'm experiencing chest pain and my smart watches is indicating that my heart rate is irregular, for example, maybe I shouldn't be ignoring this.

A heart attack isn't likely to cause an irregular heartbeat (at least not until well after the damage has been done). It's common for heart attacks to cause cardiac conduction anomalies called 'blocks', but these generally don't result in any irregularity of the pulse.

Yeah, I'm simply throwing out a strawman. I have no idea what's possible or important.

http://en.m.wikipedia.org/wiki/Straw_man

The important idea is that I'm not asking the wearable to tell someone that they're having a heart attack but simply indicate some one "test" is not within range.

Unfortunately, there aren't any tests that could be run at the wrist that would be even remotely specific for an MI.

Really the only thing I can think of is some sort of transcutaneous monitoring of troponin levels in the blood, but that's hard to do (without needles) and a late indicator... troponin levels don't start rising for a few hours after the damage has started.

While I was waiting to go into the angiogram, I was feeling my pulse... it was weird, there was three beats, then a gap, or three regular beats and a fourth straight after the third... was fascinating to listen to...

Apparently I'm weird because I wanted to watch the angio. They kept telling me that they "didn't need my help" :)

I was saying "how often do you get to see your insides?"

Cool. That sounds like a pretty classic 2nd Degree Type 1 Atrioventricular Block (also know as a Wenckebach block).

If the area of infarct impacts a part of the heart responsible for electrical conduction, stuff like that can absolutely happen, but it's not especially common.

> Edit: my ECG knowledge is a bit rusty- 2 points of contact is enough to produce a single waveform reading...

Any just to clarify further... you'd need two points of contact that complete an electrical circuit. You couldn't just wear another watch.

You _could_ wear two watches and have a small wire that you use to connect them together when you want to check, but that's only going to give you Lead I, which is one of the less useful leads (and it's completely useless in isolation).

If you really wanted to get crazy, a watch on your right wrist connected to an anklet on your left ankle would give you Lead II, which could at least get you a look at the inferior aspect of the heart (and therefore the RCA).

But I'm just getting silly now... If you think you're having a heart attack, call an ambulance. They'll do a full 12 (or 15) lead ECG right in your bedroom.

It would be neat if someday this could be built into clothing. Maybe not for the mainstream, but for people who are at high risk. Just a thought.

"Pulse and heart rate are simply not useful (neither sensitive or specific) criteria for detecting MI's"

I have a statistical medical question. Is the problem that they're completely unrelated, or that interpersonal variation is larger than the typical impact?

Very long term data analysis with a sudden change might be much different than the experience of a ER doc seeing someone for the first time.

I guess the relevant data source would be someone hooked up to monitoring gear in the hospital when they have a second heart attack while onsite... it might not even be visually obvious but perhaps a detailed statistical analysis would show something before/after.

If it can accurately monitor your heart beats, then I believe it should be able to identify patterns that signal an impending heart attack. I'm not a doctor tho, so don't take me too seriously.

Edit: Apparently I'm wrong, I know nothing about ECG.

Honestly I'd go ahead and just strikethrough your entire comment. This is terrible advice.

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