One of the most common reasons a child is referred to see a Pediatric Cardiology specialist is because a heart murmur is heard at the time of a routine physical exam. Normally, the heart just makes a thumping sound as the valves close in a steady rhythm. A murmur is an additional "whoosh" or swishing sound that is heard between the regular "thump-thump." Most of the time, heart murmurs are not related to any underlying heart disease at all, and they are simply extra sounds made as blood flows through a normal heart. Some of the time, murmurs are caused by holes or defects in the normal heart tissues. Murmurs can also be produced when there is a problem with one of the heart valves (i.e. a valve that is too small or a valve that is leaking). Heart murmurs are often subtle and it can be difficult for physicians to tell the difference between innocent murmurs and pathologic murmurs by simply listening. Murmurs that sound abnormal are often evaluated with an echocardiogram. This is a type of ultrasound that creates pictures of the heart's chambers and evaluates blood flow across the heart valves.