I've found a place
http://www.pdadumedecin.com/progmedlogiciels.html (it's in french , but you can easely find the 2 devices )where there are 2 devices that unable you to use pda/PPC in order to make EKG , they seem quite expensive :see for Pocketview EKG at :
http://www.emssupply.com/pocketview.htm ; the other link seems unefficient (midmarkdiagnostic.com).I hope it will help you .