Heart Arythmia and cycling

I haven't yet been diagnosed, but I'm going to the doctor sometime soon and kind of expecting it from the information I got on Mayoclinic's site online.

I've had a sort of arythmia/fluttering in my chest on and off sporadically for years... I'm just now really getting into biking so I want to make sure that the strain I put on my out-of-shape heart doesn't kill me. (probably a good move)
I've read that it's very very rarely a life-threatening problem...
I'm wondering if anyone here has been diagnosed, what treatment they have and how riding with arythmia has been ...

Please get to the DR to get an offical check-up!

Long story short, my mother was diagnosed with a ventrical arythmia (completely mispelled, but I'm feeling to lazy to look up the correct spelling).

She's now on meds to help control the problem.

She's never been a cyclist, but both before diagnosis/treatment and after diagnosis, she's remained active in doing some sort of cardiovascular activity multiple times a week.

Her DR's encourage activity - it will only help her. When her blood pressure increased, they did suggest that she stop weight lifting untill it was back under control.

But nothing can subsitute for talking to your DR about all of this!

I'm not going to let this slip... I'm making the appt. soon, don't worry. =)