[thedoc (OP)]

Paul Anderson asked the Naked Scientists:
   
A Samoan workmate told me her grandmother needed a pacemaker but they I'd not work in the islands because of the heat. I wonder if a pouch woven of nano fibers could enclose the pacemaker in the body. The next question is what goes through the nanotubes to keep the pacemaker cool. We need some sort of heat exchanger and any liquid obviously cannot be toxic in case it leaks.

I was thinking that if it was just water then with some plumbing

It could be hooked up to the urinary tract. However if it is going to be self contained then the liquid (whatever it might be) would just continue being recycled. Another thought is having a loop of the urinary tract pass by it to cool it, but I don't know the temperature of urine in the tropics compared with more temperate climes.  I suppose this all comes under biomechanics or something.


What do you think?

[alancalverd]

Not a problem, surely. The inside of every human body is at 37°C or thereabouts - you die if it exceeds 40 for an extended period. Any decent bit of electronics will work perfectly well up to 50°C. Interestingly, the reason cheap wristwatches keep good time is because the body is a good thermostat!

[evan_au]

I don't think the problem is the temperature once it's implanted - the main problems will be keeping it cool during transport before implantation.

Having the right tools & training to program its settings and read back its performance log are also a challenge.

Plus, you need an economy that can afford to spend tens of thousands of dollars/pounds on one patient, for what is effectively an electronic device with a non-replaceable battery.

It is at least a decade away from clinical availability, but some promising results have been seen recently in pigs, transforming existing heart cells into pacemaker cells. These don't need their batteries changed every few years.

[alancalverd]

It doesn't need to be kept particularly cool in transportation - anything less than 50°C (too hot to touch) won't hurt the device. Pacemakers are fitted in India and Australia where it's a lot hotter than Samoa. The cost of a pacemaker is in the region of £2000 - say $3500, and the cost of insertion is about the same - it's a pretty routine operation. Postop sterility and rehabilitation are a bigger problem but not beyond the means of an educated nursing service.

[syhprum]

I do not see why there should be any problem recharging the batteries of a pacemaker via an induction loop, mobile phones can be charged by this method and they have a much larger power consumption

[alancalverd]

I did some work on this a few years ago in connection with a heart assist pump. That needs daily recharging because it has a significant power consumption, and transcutaneous induction is the best way to avoid infection. However a pacemaker is quite likely to need reworking because of broken, corroded or displaced wiring before  the battery has failed, and the operation is relatively simple, so induction recharging is less of a big deal and just one more thing to go wrong.