Tuesday, July 22, 2014

Using the AliveCor Heart Monitor

Every few months, I feel a slight flutter in my chest, almost like a cough but coming not from the lungs or throat but from something deeper inside. It seems to come and go randomly, though I’ve noticed it is often triggered if I’ve had wine to drink or if I haven’t had enough sleep. No big deal, just something I observe about myself. Long ago, by coincidence, one of these episodes happened while I was at the doctor’s office having an annual physical, and the doctor too shrugged it off: a heart arrhythmia, perfectly normal. He told me the technical term for the exact type of arrhythmia, but that was long ago and I’ve forgotten. Now, maybe I’ve found a way to know for sure.

For the past week I’ve been using the new AliveCor Heart Monitor, a $200 iPhone case that gives me a high-fidelity Lead I ECG any time, any where I carry my smartphone. Here’s the sample I took this morning, right after waking up:
ECG 20140722052227 pdf 1 page
The device is just a normal iPhone case — with a funny two-part metal bulge on the back that acts as a two-lead electrode. You hold it with your fingers and it measures your ECG. Just like that! With FDA 510(k) clearance and scientifically validated for "excellent sensitivity (0.962), specificity (0.975), and accuracy (0.968) for beat-to-beat discrimination of an irregular pulse during AF from sinus rhythm”, it’s got serious medical chops too. The first time you use it, you send your results to trained technicians, who send you back a report (in my case, summarized as “normal sinus rhythm”). Each time after that, you’re given the option to send the results again as an in-app purchase:  $12 to a US Board Certified cardiologist, $5 for a 30-min turnaround by a certified technician, or $2 for 24-hour turnaround.

Unfortunately, there’s apparently no API, so although you can send each result (PDF) by email, there’s no automatic way to upload to Zenobase, for example, so you can easily compare with other self-tracking results.

The technology was invented by cardiologist David Albert using hardware that communicates with the phone via a clever, patented process that uses low-frequency, inaudible sound waves picked up by the phone’s microphone. No need to pair bluetooth with the device, no need for any physical connection to the phone at all.

Satish Misra is a medical doctor who wrote a balanced and thorough review, pointing out the wonderful breakthroughs possible with such a device, but also noting that because it doesn’t detect some important heart ailments as well as a full-scale ECG, it can provide false security. He notes, incidentally, that the US Preventative Services Task Force rates ECG screening generally (not just for this device) a “D” as a medical test:   “recommends against routinely providing to asymptomatic patients”. (They say that about exercise treadmill tests and coronary calcium scanning too, for what that’s worth.)

We’ll see what happens in my case. I really want to know more about my arrhythmia and it’s nice to know that, the next time it happens it’ll be easy for me to log it accurately.

By the way, whether you have an AliveCor or not, I wish everyone would join the Health eHeart study at the University of California San Francisco. You fill out a medical survey, give them your email address, and agree to be a long-term participant in their study. They especially want people who like to use gadgets — like the AliveCor — so they can collect as much data as possible. (Obviously, they have top-notch privacy standards to ensure your data remains confidential). If everyone did this, science would have a big head start in finding how to prevent heart disease.