3 ms·

Well the 12 lead is more finnessed than that - essentially without a 12 lead your ability to definitively rule out an acute heart attack is completely impaired.

by robbiep 10y ago

Well the 12 lead is more finnessed than that - essentially without a 12 lead your ability to definitively rule out an acute heart attack is completely impaired. 5 lead ECGs will still miss (some high percentage, above 10% and below 50%) of heart attacks. A one (two?) lead ecg as you describe is not going to tell anyone what is going on with ST segments, particularly as you would be only looking at your aVR or aVL(depending on which way you sum the currents).

rosser 10y ago
Yeah, but anyone who's trying to dx (or, worse, rule out) an AMI on the basis of what their Apple Watch can report is ... yeah, I don't even know what they are. Not the sharpest pencil in the box, for a start.
JshWright 10y ago
The augmented leads (aVR, aVL, and aVF) require a minimum of three electrodes (multiple electrodes are connected to ground). An electrode on each arm gives you Lead I. Lead I is not as useful as Lead II, but it's still plenty useful for diagnosing all sorts of cardiac issues (there's a lot more that can go wrong with your heart than just an MI).
- forgotpwagain 10y ago
  Presumably a single lead would still be able to detect certain arrhythmias? I.e. if there are no QRS complexes, then there may be something wrong with the person wearing the device. There are benign explanations for why the signal might be weak but also lethal causes like Vfib -- with a few additional, I don't think it's implausible for a device to be able to make the decision to ask the user "hey, are you okay?" and then potentially seek help if the user doesn't confirm that they are OK within some set period.
  - JshWright 10y ago
    Absolutely. Consider the fact that an AED only has one lead to work with, and it is able to recognize a couple different lethal arrhythmias in order to deliver a shock (and more importantly, _not_ deliver a shock at any other time). To be clear, by "lead" here, I mean a pair of electrodes. A single electrode (like you might put on a watch) is useless.

by robbiep 10y ago

rosser 10y ago

Yeah, but anyone who's trying to dx (or, worse, rule out) an AMI on the basis of what their Apple Watch can report is ... yeah, I don't even know what they are. Not the sharpest pencil in the box, for a start.

JshWright 10y ago

The augmented leads (aVR, aVL, and aVF) require a minimum of three electrodes (multiple electrodes are connected to ground). An electrode on each arm gives you Lead I. Lead I is not as useful as Lead II, but it's still plenty useful for diagnosing all sorts of cardiac issues (there's a lot more that can go wrong with your heart than just an MI).

forgotpwagain 10y ago
Presumably a single lead would still be able to detect certain arrhythmias? I.e. if there are no QRS complexes, then there may be something wrong with the person wearing the device. There are benign explanations for why the signal might be weak but also lethal causes like Vfib -- with a few additional, I don't think it's implausible for a device to be able to make the decision to ask the user "hey, are you okay?" and then potentially seek help if the user doesn't confirm that they are OK within some set period.
- JshWright 10y ago
  Absolutely. Consider the fact that an AED only has one lead to work with, and it is able to recognize a couple different lethal arrhythmias in order to deliver a shock (and more importantly, _not_ deliver a shock at any other time). To be clear, by "lead" here, I mean a pair of electrodes. A single electrode (like you might put on a watch) is useless.