If you hear a heart murmur in a young child...
...make sure to auscultate while they are both lying down and sitting/standing up in order to differentiate between Still's murmur and a venous hum. If you hear a low, "twangy" murmur while the child is "lying still," then it is probably a Still's murmur. If you hear a higher-pitched murmur while the child is sitting up, then it is likely a venous hum. You can test this hypothesis by having child tilt her head to look up at the ceiling (venous hum gets louder) or look at the floor (venous hum gets softer).
Pediatric Heart Specialists represent a group of physicians dedicated to the treatment of heart disease in children.
Pro-Tip: For a sports physical, it is also a good idea to have the athlete squat and stand to listen for the non-valvular murmur of hypertrophic cardiomyopathy.