I had recently been to a cardiologist to get a series of test for shortness of breath, tightness in chest, soreness in shoulders, etc.. during exertion. On the basic stress test, it came back 'positive' - I reached my max HR of 180 in just over 5 minutes (I'm 40). So I did a echocardiogram, and a nuclear stress test. Both results showed 'normal', however, there was a trace amount of leakage in both valves, but was told that it was just a trace, and nothing serious. This thing is really nothing new for me - I've had this fast HR during exercise ever since I was a kid. Just the discomfort is increasing a bit now, and as I age a bit, it is more concerning to me. So, the question is: If, as the test shows, I am 'normal', why would my HR go up so fast and I am experiencing these discomforts? For instance, when I am backpacking on fairly level ground, moving along at about 2- 2.5 mph, my sustained HR is about 172 - 176 bpm. Start pulling hills, and it is easily up to, or over, 200 bpm. They did also perform a PFT test and that came back normal. Should I seek a second opinion, or is this truly normal? While I don't think I'll get to the point where I'll feel I'll have a heart attack or something like that, I am concerned that my heart working this hard all these years will eventually 'wear out'. Any advice?