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Comment on Body Hacking: Thoughts Regarding My Magnet Implant

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Body modification? Pacemaker here.

Every six months I have to go in for a tuneup, a wireless data dump & service testing. Having having one's heart slowed to sub-40bpm via a few taps on a screen is...odd. Printed report tells assorted stories of daily activity periods, odd events, heart rate hitting programmed thresholds, etc. There have been some confluence of proximity & programming causing twitching under some circumstances (couldn't sleep on my left side for a year due to a lead pressing on & convulsing diaphragm) which were fixed completely thru software settings. Have a minimum threshold programmed in, and if it's set too high (say, 60bpm) and I relax deeply can feel it kicking in with "go faster!"

Proved quite useful a couple weeks back. Suffered a random onset of aortic flutter (can happen to anyone, just sorta happens), where a natural short-circuit in the beat-signal nerves sent the heart rate up to 349bpm (neatly documented on the printed data dump). For most people, this means a very scary and tense race to the emergency room, with AED paddles & drugs to bring it down until the problem can be surgically eliminated. My pacemaker hit the brakes at 150bpm, leaving me functional to wander in to the ER at my convenience; there, a tech was brought in to set up a more aggressive flutter-control program (70-100bpm more aware of actual physical needs). That kept things manageable until the drive-thru heart surgery to fix the problem (1 hour to send a probe up a vein to find & burn out the short, 3 hours rest, then discharged). Wasn't what the pacer was installed to handle (ventricular resynchronization), but the "while we're installing this, let's add a wire and program in some other someday-useful stuff" has indeed proven useful.

Other body modification is a mechanical heart valve. I tick. I've been confused with clocks.

Yes, MRIs are completely out of the question now. Work near a small one and get nervous walking by the door.

OK, so these weren't exactly voluntary. Choice aside, being a cyborg does make for interesting experiences & conversations.

ETA: BTW, not looking forward to replacing the battery. At least the device has been saying the battery will last another four years - for the last four years.

That's a fascinating read.

This kind of control and capability makes me wonder if they won't someday become common in a preventative/health monitoring role instead of only for cardiac defects. The risk during installation and problems with MRI seem pretty serious, so I doubt it could happen soon, but it's not impossible.

I wonder what some sort of self-assembing/modular device that can be fed in chunks through a vein catheter or keyhole surgery, and built in-situ could be plausible.

Not sure what to do about the MRI issue though. They're only going to get more common as we figure out superconductors, and they have none of the radiation downsides of CT. Maybe non-metallic construction, or perhaps when milli-Tesla MRI becomes a reasonable alternative?

Is the battery in yours single use, or recharged via induction loop?

Pacemaker installation is now an arthroscopic outpatient process. (Mine was in conjunction with open-heart valve replacement - not so much an outpatient process, but they're starting to do 'em that way too now.)

Battery is single-use. I wouldn't want a rechargeable, because that would require far more frequent charging - to wit, much more room for error. Missing a charge would mean a dead...me. I'll take the ~5-8 year hard-way replacement.

Pity they don't use nukes anymore; they worked great, until people started cremating them.

According to http://www.orau.org/ptp/collection/Miscellaneous/pacemaker.h... they're titanium cased and designed to withstand cremation, although I have no idea if that's true in practice.

What surprised me was that the total expected exposure was much higher for the patients spouse that the patient themselves. It's got twice the thickness of partner in which to be absorbed, but there's only close exposure for maybe 8-10 hours a day, and the inverse square to deal with.

Maybe some were. I'm basing it off a comment from a professor regarding nuclear power in small electronics. Quote (from memory, thus unreliable) below:

"So, they tested these things for all the possible stresses they would encounter -- high G maneuver and impact if they were in a car wreck, crushing force, electrical damage (from a lightening strike, etc), anything that they were likely to encounter whilst inside a human body. However, they were never thermally tested -- after all, why would the human body ever experience >1000 degrees F?

Ends up the answer is cremation. So, for a while, a major hazard around funeral homes was radioactive crematoriums."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1279940/

Also apparently a mercury hazard.

"The whole body exposure is estimated to be approximately 0.1 rem per year to the patient and approximately 7.5 mrem per year to the patient's spouse." In the same units, 100mrem (patient) to 7.5mrem (spouse). Using the xkcd[1] radiation chart, that's the equivalent of a head CT scan every two years for the patient, and 2 plane flights a year for the partner.

1. http://xkcd.com/radiation/

Argh, I've looked at that page several times, and each time I've managed to misread a 'm' on that 0.1 rem figure.

Thanks for clearing it up!

Before we start using them in those roles (and massively expand "install base"), we're going to have to solve the security issues http://www.schneier.com/blog/archives/2008/03/hacking_medica....

Apologies in advance for not actually commenting on body hacking, but did you serve in the military? I'm trying to decide whether the writing style where you omit subjects and occasionally verbs comes from the military only, or whether it's more pervasive.

Nope, no military service. I do make a point of refining my writing style, with an underlying avoidance of repeating words leading to a reliance on implied words. Comes in part from frequent blogging, where reader attention spans are short and criticism for imperfection & incompleteness abound - to wit, high density content pays off. I've also always been of few words, to the point where one friend dubbed me "Noun Verb" because I tended to talk that way. My software is similar, concentrating on terse clarity, heavy on references and semantic implications. I'll spend a lot of time minimizing what's published, be it English or C++. Music of Philip Glass & other minimalists was rather influential and formative.

Upshot: it's just me.

I know this is getting really tangential, but prolongued exposure to the Japanese language (where they usually drop the leading I/he/she/we on a sentence) has made me start doing this myself fairly often in written communication, ala "sounds good, arriving soon."

I must admit, I rarely read comments the length of your original one (in a rush / short attention span; like you said). Once I started reading the first few lines, however, I found myself unable to stop and I ended up reading the whole thing.

So, I guess it works.

About that wireless connection to the device connected to your heart, and such things as security and bugs, here's a really excellent talk by Karen Sandler. https://www.youtube.com/watch?v=5XDTQLa3NjE

Having having one's heart slowed to sub-40bpm via a few taps on a screen is...odd.

Could you describe in detail what that experience was like? That's incredible.

Imagine being dropped from a great height with no sense of acceleration, just a sense of "oh my" brought on by rising innards.

One tech told more about the test. They really want to just shut the pacer off to see what the heart does without it. Problem is, a lot of people fall into a deep depression for several days. Even with it still beating, albeit slow, I felt rather...off...for the rest of the day.

Presumably a period of faster-than-normal beating would be similar to being dosed with adrenaline? It's intriguing how blood flow rates affect mood.

Really fascinating. Thanks for sharing!

Thanks for that it was really a much better story than a magnetic implant which comes off as silly to me.

If you ever write up more I sure would be interested.

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