Heart murmur causes are divided into two types: "innocent" and "abnormal." Common innocent heart murmur causes include physical exhaustion, fever, and hormonal imbalances. Abnormal heart murmur causes, on the other hand, are significantly more serious and should be given medical attention. Congenital heart defects, infections, and thickening of heart valves are among the most common abnormal causes.
If the cause is innocent, heart murmurs do not pose any health threats and tend to go away with time. In innocent heart murmurs, the resulting noise is the sound of blood passing through a healthy heart, with no accompanying symptoms or signs that indicate heart disease. The extra sounds are a natural consequence of physical activity or fever. In some cases, anemia and hyperthyroidism can cause heart murmurs. Pregnancy can also trigger turbulent blood flow as the body creates more blood to nourish the fetus.
An innocent heart murmur causes no distress on an individual's overall well-being and usually disappears with time. In healthy children, heart murmurs are easily detected because there is less physical tissue between the heart and the stethoscope, which might cause uninformed parents some alarm. As children grow older, the noises become harder to hear.
Abnormal heart murmur causes include acquired heart valve disease and congenital heart disease. Heart valve disease is among the most commonly reported heart murmur causes in adults. This is usually the result of a related condition that destroys the valves, such as scar tissue from cardiac damage, advanced high blood pressure or atherosclerosis. Rheumatic fever from an untreated streptococcus infection can also damage the heart valve. Adults who have previously developed heart valve disease are vulnerable to a bacterial infection called infective endocarditis, which forms blood clots on the valve’s surface and makes heart murmurs more apparent.
In children, the most common abnormal heart murmur causes are congenital heart defects, deformities in the heart's structure resulting from errors in prenatal development. These structural defects often involve the heart’s interior walls, valves, and the arteries and veins that pump blood throughout the body. Many congenital defects are simple and pose no serious threats; many children born with this problem continue to live healthy, productive lives. Some cases, however, can pose serious risks to the patient's health and require medical attention soon after birth. Depending on the severity of the damage, many babies who suffer complex congenital heart problems will need special care for the rest of their lives.