This project synchronizes Lissajous waves with the information from a heartbeat. I was experimenting with brain waves from this open source eeg project http://openeeg.sourceforge.net/doc/index.html , but there was to much interference for accurate readings. I did find an interesting way of getting the pulse data through the serial ports using earplugs soaked in salt water and amplifiers to amplify the weak signal. video here: http://kennyjsmith.com/otprojects/pulse.html
Nice work ;)
Have you any more details about the transducer?
Many years ago I used an IR emitter and sensor and reflected the beam off the bone in the finger. The blood pulsing modulated the signal that was reflected back and I could measure my pulse rate.