had gastric bypass 14 months ago, am reading that a low heart rate is fairly normal for us.........mine was down to 40-50 in hospital during an overnight stay, has stayed in the upper 50 s- lower 60 s for 2 weeks now, scheduled for stress test and CHF test.........dr. upped my potassium , lowered my lasix and put me on magnesium oxide , is there anything else that could be causing this, I have always had normal heart rate. I have INCREASED my exercise regiment in that 14 months, of course, and have read that can cause a lower heart rate, does my cardiologist need to know about this gastric bypass commonality with the low heart rate?