If your doctor says your heart and cardiovascular system are healthy, you can run your HR as fast as it can get. If you are healthy, then your body regulates your HR to what your body is demanding from it.
Just learn to use it to judge how much effort you are putting into your ride at any one particular moment. You'll learn that you can only maintain a certain HR level for so long. And that will tell you if you need to back off for a while to rest up for another part of the ride where you'll have to exert yourself again.
What should trouble you about HR is when it doesn't go down soon after you reduce your effort. Or worse, IMO, it doesn't increase soon after you increase your effort.
P.S. Don't over look the drugs you might take regularly. They can affect your HR during hard exertion too and you need to read all the side effects and make certain your doctor understands how seriously you do or don't exert yourself while riding. I get the idea that many doctors that don't cycle, think of just casual bike riding in a very leisurely manner when I tell them I ride. But I don't do leisurely rides. For some of my short rides I stay anaerobic for a large percentage of that ride.
Last edited by Iride01; 05-20-19 at 10:13 AM.