Firstly, although your son was diagnosed with a heart murmur, it isn't really a diagnosis in the usual sense. Rather, it is a finding on the physical exam that may or may not be associated with an actual problem. Murmurs occur because the blood flows with turbulence and that turbulence makes sounds (murmurs) which can be heard. The presence of turbulence does NOT necessarily mean that anything is wrong and murmurs are EXTREMELY common in pediatrics patients. Secondly, the evaluation of a murmur should be initiated at the time that it is found and may consist of nothing more complicated than obtaining a history and performing a thorough physical exam to determine the actual cause of the murmur. Most childhood murmurs are "innocent", meaning they are not caused by any abnormality, but are simply due to turbulent flow without abnormal anatomy. While there are murmurs that are associated with abnormalities, it's important to realize the most childhood murmurs are NOT. Ask your physician what is causing the murmur and how he or she has determined that it is an innocent murmur and that should reassure you that there isn't a problem (or lead you to ask more questions). There's a brief review attached.