I had to get a cardiac release (I had recently had an exam at my cardiologist for a minor ongoing issue) prior to getting radiation. I believe it is because there is a minor chance that there can be damage done to your heart and/or lungs during the radiation process so they want to know if there is a problem to begin with. I believe that this is "normal" to get an EKG or some type of cardiac exam prior to radiation of the breast.

My breast cancer was on the left side but very close to my armpit so I did not have to do any special breathing during radiation treatments. I had 16 radiation sessions, and have had no heart problems result.

Best of luck to you!