A heart murmur is a sound associated with turbulent blood flow in the heart. That turbulence can be normal or abnormal. Certainly, it is common to have normal/innocent heart murmurs be a bit more worrisome sounding to primary care providers, and they can easily be wrong. However, I will also say that patients who have multicystic dysplastic kidneys are also at greater risk for congenital cardiac defects. That said, your daughter is 5 years old, which means that the likelihood of a truly serious problem is low. I do think that in her case, even without seeing her, that having a pediatric cardiologist evaluate her to ensure that there is no structural cardiac defects would be important.