The following video demonstrates using an Olimex SHIELD-EKG with an Arduino UNO and a 2.8" TFT Touch Shield by Adafruit. The EKG shield has jumper settings as follows: AIN_SEL to A5 (pins 11,12) and voltage to 5V. EKG electrodes were Olimex passive electrodes. The display uses Adafruit libraries and a simple Arduino sketch.
http://youtu.be/pbVGKQprBjM (http://youtu.be/pbVGKQprBjM)