HeartWorks

HeartWorks is an application for the iPhone that monitors your heart rate. It works with heart chest strap monitors that use the Bluetooth Smart or the ANT+ technology .

It is designed to work for many hours and save all your heart rate data into a zoomable graph. You may have many sessions, keep them and view their statistics and graphs later.
It works in the background and the heart rate is even displayed as a number in the app icon.

--> Bluetooth Smart: for this to work you need the BLUE HR monitor from Wahoo. This only works on the iPhone 4S and the new iPad (and probably anything newer)

--> ANT+ : To work with an ANT+ heart monitor (chest strap) you need a "Wahoo Key" (dongle) which is an ANT+ receiver. This app does NOT work with the Digifit or Garmin ANT+ dongles though it does work with the Garmin and other ANT+ chest straps.

HeartWorks does not claim to be, nor intends to be, a medical or clinical application.

Basically, HeartWorks monitors your heart rate and saves the data. The iPhone needs to be connected to a heart rate monitor (such as a Garmin or Wahoo). For ANT+ it also needs a dongle (the "Wahoo Key" receiver that is purchased separately from Wahoo Fitness and is attached to the iOS device.
See http://www.wahoofitness.com/?affID=5209) for the Wahoo products.

For BLUE HR watch a video on http://youtu.be/egMi2gZmZv4
For ANT+ watch a video on http://youtu.be/JyYY53UvEN8