A heart murmur is a whooshing sound a physician hears with a stethoscope, representing turbulent blood flow within the heart or major blood vessels. While hearing this sound in an infant can be alarming for parents, it is common in newborns and children. The murmur itself is not a disease, but a sign requiring investigation to determine if the blood flow is normal or if it suggests an underlying structural issue.
The Two Categories of Infant Heart Murmurs
Heart murmurs are classified into two types: innocent and pathological. Innocent murmurs, also known as functional or physiologic murmurs, are harmless and do not indicate underlying heart disease or structural defect. These sounds are created by the rapid, normal flow of blood through a healthy heart, sometimes intensified by high cardiac output, such as during a fever or excitement.
Innocent murmurs are common, with most children experiencing one early in life. They often resolve on their own as the infant grows and heart structures mature, frequently disappearing by adolescence. No treatment or restriction on activity is required, and they do not affect the child’s long-term health.
A pathological murmur is caused by an abnormality in the heart’s structure, such as a congenital heart defect. These defects can include holes in the heart walls (septal defects) or issues with the heart valves, which may be narrowed, leaky, or too small. Pathological murmurs are rare, occurring in less than one percent of children. They require careful evaluation as they may indicate a condition needing medical or procedural intervention.
Distinct Signs That Require Immediate Medical Attention
The most important factor in distinguishing a harmless murmur from a serious one is the presence of accompanying symptoms. A baby with an innocent murmur is typically asymptomatic, appearing healthy and developing normally. If a heart murmur is heard alongside other physical signs, it suggests the murmur is pathological and requires urgent medical review.
One concerning sign is cyanosis, which is a bluish tint to the skin, particularly visible around the lips, tongue, or fingertips. This discoloration indicates poor oxygen circulation, a direct sign of a potentially severe heart or lung issue. Difficulty with feeding, such as becoming excessively sweaty or short of breath during a session, also points toward cardiac stress.
Poor weight gain or a failure to thrive can also signal that the heart is working too hard. Rapid breathing (tachypnea) or increased respiratory effort unrelated to a respiratory illness are other red flags. These symptoms suggest the baby’s circulatory system is struggling to meet the body’s demands, warranting immediate consultation.
Diagnostic Tools Used to Evaluate Murmurs
When a physician suspects a murmur is pathological, they rely on non-invasive tests to confirm the diagnosis and visualize the heart’s inner workings. The primary tool used by pediatric cardiologists is the echocardiogram (echo), which uses sound waves to create a moving image of the heart, similar to an ultrasound.
The echocardiogram allows the specialist to assess the heart’s structure, checking for defects like holes in the septum or abnormal valve function. It also provides information on the direction and speed of blood flow, helping determine the severity of any detected abnormality.
An electrocardiogram (EKG or ECG) may also be performed to record the electrical activity of the heart. While the EKG is not a highly sensitive screening tool for all structural heart defects, it can reveal abnormal heart rhythms or signs of chamber enlargement that support a pathological diagnosis.
Understanding the Outlook for Serious Murmurs
For the vast majority of infants, a heart murmur is determined to be innocent, meaning the outlook is excellent with no need for future follow-up or treatment. These innocent sounds may be monitored during routine check-ups but do not require specialized care. The heart is structurally normal, and the child can lead a completely unrestricted life.
If a pathological murmur is confirmed, the course of action depends entirely on the specific structural defect and its severity. Some minor congenital heart defects, such as a small ventricular septal defect (a small hole), may close on their own over months or years, requiring only a period of close monitoring.
For more significant defects, treatment may involve medication to help the heart function more efficiently or, in some cases, surgical intervention to repair the structural problem. Advances in pediatric cardiology and cardiac surgery mean that the outcomes for most congenital heart defects are highly positive, allowing children to lead full and healthy lives.