A heart murmur is an extra or unusual sound heard during your heartbeat. Murmurs range from very faint to very loud and sometimes sound like a whooshing or swishing noise. Most heart murmurs are harmless (innocent). Sometimes a heart murmur indicates a heart problem, especially if other signs or symptoms of a heart problem are present.
Innocent, harmless murmurs are common in healthy children. A child or adult with an innocent murmur has a normal heart. Doctors can listen carefully to the heart with a stethoscope to help decide if a murmur is innocent or abnormal. They listen to the loudness, location and timing of the murmur in order to classify and describe the sound. Abnormal murmurs in children may be due to congenital heart defects—heart defects present at birth. In adults, abnormal murmurs are often due to heart valve problems caused by infection, disease or aging.