What normal and abnormal heart rhythms look like on an Apple watch
blog.cardiogr.am
blog.cardiogr.am
Many of you have helped out with the mRhythm Study we launched a couple of months ago:
https://itunes.apple.com/us/app/cardiogram/id1000017994?ls=1...
We're planning to start publishing some of the insights we're learning from the study, and we thought we'd kick off with a post on the foundations:
* How normal rhythm varies and why an "irregular pulse" is actually normal
* What optical heart rate sensors measure, and how they're different from the ECGs commonly used in hospitals.
* An example of an "irregularly irregular" abnormal heart rhythm.
* An example of a regular abnormal heart rhythm (atrial flutter)
* An answer to one of the most common questions we hear, "Could Apple Watch detect heart attacks?" (Short answer: not yet.)
If you have questions or things you're curious about for the next few posts... we'd love to hear your thoughts!
A funny aside: many of my classmates own Apple watches/Fitbit HRs. I've heard of at least one student looking back at her heart rate data from finals week and saw spike to 120 bps that was maintained throughout one of our more stressful 8-hour exams. Her fitness tracker registered it as "exercise."
Health monitoring is going to be incredibly helpful. Beyond just pulse monitoring, I'm looking forward to analyzing trace materials in sweat and the like to notice deficiencies or issues.
It's possible to have permanent A-Fib and survive - if not thrive - just fine.
The three things that can kill you indirectly are clots created by blood pooling in the heart, heart exhaustion from tachycardia, and a heart attack from possible ventricular arrhythmia.
I occasionally get A-Fib and it's consistently caused by stress - often lack of sleep (no more all-nighters...) or any situation where I have too much to do and not enough time to do it.
(That thing where people say "Hard work never killed anyone?" 100% wrong.)
Having researched it, the causes are complicated, and stress is only one predictor. There are physiological and genetic predispositions and other possible contributing factors.
So yes - GO TO A DOCTOR. You probably won't die - but you might, and it's very easily avoided.
I'm a Garmin Edge user of many years, always interested in HRM during activities. But that's not something I wear all the time. Hopefully when my Pebble Time 2 arrives something similar can be done on that platform.
I'm intrigued to see what sort of details may be captured from such a seemingly simple device.
I would also like to be able to up the number of measurements it takes. I often only use about 50% battery a day so would happily utilise the remaining charge for more regular monitoring.
One tip I've found: if you wear the watch slightly higher up your forearm, it often gets a better reading than if you wear it directly on your wrist.
It was interesting in her case to see that her heart rate jumped well before she thought it did, and that the actual "trigger" to her attack may not have been what she thought it was.
Agoraphobia? Best wishes for working through that, it certainly takes a lot of time but you can get there (or at least to a state where it doesn't happen as often).
Chest ECGs done at the hospital are often 12-lead, and those give different "angles" through the heart, which gives cardiologists more clues on exactly which parts of cardiac tissue are causing a problem.
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).
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).
To be clear, by "lead" here, I mean a pair of electrodes. A single electrode (like you might put on a watch) is useless.
(I used to be an EEG tech, and for us, the ECG was the primary thing we wanted to get rid of...)
Most clinical EEGs are related to epilepsy or similar, which usually has a particular pattern with spikes in it, but sometimes that pattern is subtle in the EEG. The spiky nature of ECG 'bleeding through' can make it a bit harder to determine the true EEG spikes from the artifact ECG patterns. Usually you will record a single-lead ECG along with the EEG, so you can see where the ECG spikes occurred and account for them in diagnosing the EEG.
This link has some clear spike-and-wave epileptic waveforms in it, but it's not always so clear-cut: https://en.wikipedia.org/wiki/Spike-and-wave
Finally, there's not a lot of overlap between neurological and cardiac patients - there's rarely any need for an EEG tech to do a full ECG (we never did, and we did approx 3200 patients/year), and full ECGs are pretty commonly done in most other places in a hospital anyway.