hrm with a heart condition?

So I am looking to get a hrm, but not sure what to get. I have a heart problem, which required corrective surgery as a kid, and will require a valve replacement when I am older. While working out, I am supposed to stay at the lower end of the heart rate scale and would like to get a hrm.

Here is my concern. I know the better models have a chest strap, like the polar f7. When my heart beats, it has a click, which is like a murmur, only much stronger. So when my heart rate is elevated, and you feel my heart beating in my chest, it is difficult to take my pulse from the chest or carotid, because it almost feels like my heart is beating double time. This is much less defined in my wrist pulse. I am concerned that if I invest in a good hrm, I won't get an accurate reading with the chest strap.

So what is a good quality hrm that doesn't have a chest strap? I am also considering a bodymedia fit instead, as I would love something that calculates tdee. But, how good is that at calculating calories burned running, or using an elliptical? I can't afford both.

(To qualify this, yes I have consulted a dr about working out and everything I am doing is dr approved. Just looking for advice on hrms.)

Thank you everyone#