Some babies who seem to have normal growth and development are found to have a heart murmur on auscultation when they have child care, vaccinations, kindergarten checkups or cold visits, and young parents are very anxious that their baby has a heart attack. Let’s see what a heart murmur is all about! How does a heart murmur form? Heart murmurs are related to heart valve activity, acceleration and deceleration of blood flow, and myocardial contraction. Normal blood flow is laminar and does not produce sound. When the blood flow speed changes, abnormal blood flow channels or abnormal blood flow diameter and blood viscosity changes, the laminar flow can turn into turbulence or vortex and impact the heart wall, large vessel wall, valves and tendons, etc., causing them to vibrate and produce a murmur in the corresponding area. Is a heart murmur the same as heart disease? Heart murmurs are classified into two categories: physiological murmurs and pathological murmurs, depending on the presence or absence of abnormal heart anatomy. A heart murmur heard when the anatomy of the heart is normal is a physiologic murmur. About half of healthy children have physiological murmurs. Physiological murmur is generally softer, wind-like, 1-2 levels of loudness, short duration, time frame accounts for the first half of the systole, late systole can not be heard, loudness from loud to light, not conductive, no tremor, fever, anemia, emotional excitement can make it tend to loud, repeated examination murmur can also be sometimes absent, sometimes with the change of position and change, no impact on human health. Most of the physiological murmurs will disappear naturally with age. In people with normal cardiac anatomy, if there is fever, anemia or hyperthyroidism, the basal metabolic rate increases and the blood flow speed increases, a soft wind-like murmur can be heard in the precordial region, which is a functional murmur. The functional murmur usually disappears after the primary disease is cured because there is no structural abnormality in the heart. The persistence of the primary disease may have irreversible effects on cardiac function over time, resulting in secondary changes such as cardiac enlargement, arrhythmias, and cardiac insufficiency. The pathological murmur is often coarse, high in pitch, often greater than 3 in loudness, may be tremulous and conductive, and the murmur is of long duration and may cover the entire systolic and/or diastolic period. Blood flow is accelerated and turbulent through pathological stenoses such as valve stenosis or incomplete closure, endocardial septal defects, and vascular stenosis, producing a heart murmur. Common pediatric congenital heart diseases include atrial septal defect, ventricular septal defect, patent ductus arteriosus, and pulmonary artery stenosis.