Hi there. My son is going to be six next month. Last year he was showing symptoms that led us to have an ultrasound of the heart done, as well as a 24 hour holter monitor . Both came back fine. His pediatrician , which is also the pediatric cardiologist in our area, did say that his heart beat was fast for his age at a resting rate. The symptoms he was having, that have subsided over the past 3 months or so, were: grab his chest and say how hard his heart was pounding and how fast (it was visible from across the room), coughing after very minimal play (5 minutes in bounce house), tire out sooner than everyone else (literally drop to the ground and lay there for a while). Now, over the past three days, I have noticed a blue vein across his left upper chest/ shoulder region, that is about 5 or so inches long. I am going to call his pediatrician as soon as they open, but would really appreciate a second opinion. I am not sure if this is normal for a young boy, or not. I freak, because my brother-in-law past away from an enlarged heart, and heart problems run heavily on my husband s side of the family. I have high blood pressure, high cholesterol , and a large network of blue veins all over my body. Thank you for any insight you may have. I really appreciate your time!!!!