What causes a Normal (Innocent) Heart Murmur?
Many conditions, all within normal limits, may cause the blood to flow with turbulence leading to a heart murmur on auscultation. All these conditions do not indicate any abnormality and cause no ill effect on ones health. Some of the conditions causing an innocent heart murmur are: Small blood vessels to the lungs (pulmonary arteries) in newborn children (Peripheral Pulmonary Stenosis or PPS): Newborn babies have small blood vessels to the lungs, this is because while they were in their mothers’ uterus, there was very little blood flow to the lungs since babies do not breath prior to birth. This will cause the blood vessels to the lungs to be small (since blood flow causes blood vessels to grow). Once the child is born, blood flow increases tremendously to the lungs, this will cause blood to be turbulent as it crosses these relatively small blood vessels, this turbulence will produce a heart murmur. This disappears at about 2 months of age.
