Thanks again you all nice people!
Structure is fine so it looks like the problem is on the control-system side of the heart just like doc suspected in beginning. I've got now beta-blockers for calm down heart. I'm just finding out the right dozing, if I take too much, heart rate will go too low and it won't raise enough when training.
Anyway, doctor said that becouse the heart structure is fine, these arrhytmias shouldn't thread my life at the moment. He said that these could be handled also by surgical operation, but there are always risks when doing that. So it's better to try first something else in this case, becouse these arrhytmias aren't so dangerous right now.
Sometimes they can even get away when getting older. All pathways usually will get worse then and the wrong ones can just fade away.
I talked with my dad about these things, he said that he had also same kind of a problems in my age, but they just got better without any treatment. Doc's kept him even in a hospital for some days but there wasn't nothing really bad to be found.
So just have to look what happens! Maybe the shooting would be right kind of a sport for me becouse of beta-blockers? -- Hell no!