Recording a heartbeat?

["Heather Perkins" landonewts]

Hello, all -

Maybe this is not technically a question about nature recording, but  
it does involve the preservation of an interior soundscape, and I'd  
love to tap into the wisdom of this list...

I need to record a heartbeat. A friend of mine is having open-heart  
surgery to repair a faulty valve, and she wants a recording of her  
murmuring heart before the surgery changes it.

I can't throw money at the problem, so ingenuity will be key. I have  
a cheap lavalier, some home-made contact mics, an SM-58, some cheap  
dynamics, and a couple of nice condenser mics. I can probably lay my  
hands on a stethoscope.

Any ideas?

Let me know - and thanks!

Heather Perkins
Sound Designer - Composer - Mad Scientist
WaterDog Studio & Land-O-Newts! Records