I have been on a snri for fifteen years. i use to have a low pulse -70s . the norepinephrine has caused my pulse to be in the 90s . could a pulse in the 90s cause a heart problem? i need my antidepressant and dont want to discontinue?

I believe that a continuous resting heart rate in the 90's is harmful in the long run. Is your blood pressure also elevated? I understand your reluctance in stopping your antidepressant. Although beta blocker treatment combined with SNRI can be problematic, I wonder if your MD would be willing to try you on a tiny dose of a beta blocker, with careful monitoring, ,to lower your heart rate.

You say your pulse used to be in the 70's (this pulse rate is not low, but average, low if less than 60). Norepinephrine is a adrenergic hormone which sometimes causes tachycardia but it does not mean a serotonin-norepinephrine reuptake inhibitor such as the one you take has that effect just because it has norepinephrine in its name. If you think it does, you can request a different SNRI.