Source code below demonstrates how to display an electrocardiogram on the Mac using the 'Processing' app with an Arduino UNO and Olimex EKG/EMG Shield. Images and reference are included. Processing also runs on Windows and Linux, but was not tested on these platforms.
https://github.com/vsquared/ECG_UNO_Processing (https://github.com/vsquared/ECG_UNO_Processing)
Thank you for sharing your experience! Much needed post - we never had a Mac machine here.
Best regards,
Lub/OLIMEX