heart rate at 6weeks what's normal?

Had to go the er last night for some bleeding after running many test they said that my baby's heart rate was at 117 but that it was tonlow for 6 weeks and there is a chance I will miscarry because I was bleeding and the heart rate was low? But my hcg levels measured at 42,000? Anyone experienced this before any advice? I'm so worried Have an appointment with my primary care physician tomorrow hopefully she can tell me more and put me at ease!