The dr. wrote in my chart that i have a grade 2 blowing murmur. didn't mention it to me. ekg was nl and no dr seems to have heard it before or since. can murmurs come and go? should i be concerned?

Can come and go: Heart murmurs are just sounds that the doctor hears as blood flows through the valves in the heart. Sometimes stress or infection / fever can cause a heart murmur to be heard where none was heard before. Sometimes there is a condition of a heart valve developing. Usually with a grade2 blowing murmur there is no concern but it should be rechecked in 6 months.

Murmurs canbe tricky: It does seem odd that he would not have mentioned it to you, especially to ask if anyone had told you you have a murmur before, but your ECG came out normal which is reassuring. You could consider having an echocardiogram done to see if there are any structural problems with the valves or how the heart contracts that could cause what he heard. Most likely it is a benign murmur.