If you are super concerned, talk to your doctor, but it seems like you should run as far as you can comfortably run, ignoring your heart rate while you are doing it. It should only help in the long run, since your heart will get used to the increased activity and come up with a lower resting heart rate as a result.
I don't know what you Resting Heart Rate is , but mine is around 50 and I'm very fit for my age of 64.
Here are your Training zones based on your age and assumed RHR of 50
Fat Burning: From 115 to 128 beats per minute
Aerobic: From 128 to 141 beats per minute
Steady State: From 141 to 154 beats per minute
Anaerobic: From 154 to 167 beats per minute
Maximal: From 167 to 180 beats per minute
You are in the Maximal which is clearly around the danger zone!
Something does not dd up here, but if your numbers are correct
check with your doctor to make sure it's OK to train in that range.