My 16 year old son was just diagnosed with a heart murmur and his EKG showed RBBB. His symptoms that lead us to be checked were, dyspnea after exercise, cough, nausea or emesis after racing, low energy and tightness in chest like he can t expand his lungs. He is a runner and runs about 30-40 miles a week and is in track. He is to have an echo, how serious is this?