Types of Infant Heart Murmurs

Julie Kirk
Contributor: Susie McGee
Reviewed by Terri Forehand RN
Doctor examining baby

If your doctor diagnoses your child with a heart murmur, how concerned should you be? It may depend on the type of heart murmur your baby has as well as its severity.

What Is an Infant Heart Murmur?

Most of the time, murmurs are detected by simply listening through a stethoscope. A murmur is typically a sound that is detected between the beats of the heart. Heart murmurs are very common in infants and children, occurring in as many as 70 percent of kids. In most cases, there is nothing to worry about. In some cases, infants may be diagnosed with a heart murmur in the first few months after birth. In the instance of a child so young, typically a pediatric cardiologist will be consulted to rule out any abnormalities or other possible concerning issues.

Testing a Baby's Heart Murmur

Doctors may perform a variety of tests on your baby if she has a suspected heart murmur to rule out any serious conditions. These tests include:

  • Electrocardiogram (ECG or EKG) - this test uses electrodes that are placed on the chest, arms, and legs that will measure the electrical beats of the heart.
  • Echocardiogram - this test uses ultrasound to image the heart. It checks the structure, anatomy, and function of the heart as-well-as blood flow.
  • Chest X-ray - this test uses a small amount of radiation to image the structure of the heart.

Hospital staff will also monitor your baby's breathing and observe his skin color, noting any changes, such as a blue skin tone. If the testing and observations are normal, then the infant is usually given the diagnosis of an innocent heart murmur. Periodic check-ups are usually all that is necessary.

Innocent Heart Murmurs in Babies and Children

Most of the time, this murmur occurs simply because of the way the blood flows through the baby's heart. Young children usually grow out of their heart murmurs without any special precautions or care, thus creating the term "innocent murmurs." In many cases, a child's innocent heart murmur may not be detected until he has reached his first birthday and may continue to go unnoticed until he reaches school age. Usually, the diagnosis is made during a routine doctor's visit. In the majority of cases, your doctor will simply monitor the murmur with each visit. However, if your pediatrician has any concerns, he or she may refer your child to a pediatric cardiologist for further testing.

More Serious Problems Indicated by a Baby's Heart Murmur

Doctor listening to chest of baby

Heart murmurs in infants can indicate a more serious problem, however. The most common cause of these abnormalities is a congenital heart defect. The term congenital heart defect is used to describe many types of abnormalities of the heart, valves or associated blood vessels. This defect typically occurs when the heart and its surrounding valves and blood vessels fail to develop normally during fetal development. In the U.S., about 1 in 100 babies (approximately 40,000 babies) are born with a heart defect each year. Approximately 4,800 babies are born each year with a critical congenital heart defect.

Congenital Septal Defects

Congenital septal defects are basically defined as holes in the heart. The two most common congenital heart defects are a ventricular septal defect (VSD) which is a hole in the wall (septum) between the ventricles (lower heart chambers) and an atrial septal defect (ASD) which is a hole between the atria (upper chambers) of the heart. About 4 to 10 percent of babies born in the U.S. each year have septal defects.

Congenital Heart Defects and Their Prognosis

Many congenital heart defects can be treated easily or don't even need treatment. However, some babies that have a critical congenital heart defect can have serious health problems or it may even lead to death. The general prognosis for babies with any type of congenital heart defect greatly depends on when it was diagnosed, how severe the defect is and how it is to be treated. Most infant deaths from congenital heart defects occur when the baby is less than 28 days old. About 95% of babies survive non-critical congenital heart defects and about 69% of babies survive critical congenital heart defects. Overall, babies born with congenital heart defects are surviving, thriving and living longer and healthier lives.

Congenital Valve Abnormalities

Congenital valve defects generally involve heart valves that may be missing, malformed or too narrow to allow adequate blood flow. The valves also may not close properly which allows leaks to occur. In general, if the heart valves are not opening and closing appropriately, blood will not flow as it should.

Heart Damage From Other Conditions

Heart murmurs may occur due to a damaged heart and heart valves because of infections, such as rheumatic fever or endocarditis, which is an inflammation of the heart's inner lining, often caused from a bacterial infection.

Other Causes of a Baby's Heart Murmur

Other possible causes of a heart murmur include:

  • Fever
  • Infection
  • Anemia
  • Hyperthyroidism

Treating Your Baby's Heart Murmur

While innocent heart murmurs typically require no treatment whatsoever, heart murmurs that occur through either a congenital abnormality or because of an infection often need some type of treatment. A pediatric cardiologist will determine the treatment after assessing the type of problem and severity of the heart defect which has led to the murmur. In some cases, treatment can be conducted entirely through a regimen of medications. In others, surgery is needed.

Understanding Your Baby's Heart Murmur

If your baby has been diagnosed with an infant heart murmur, talk extensively with your pediatrician. Once you understand the cause of the murmur, you and your doctor can discuss the best course of action. As always, if you have any further questions about your baby's health, contact your doctor.

Types of Infant Heart Murmurs