Hearing a doctor say your baby has a “heart murmur” can be alarming. While it sounds serious, a heart murmur is simply an extra sound heard when listening to the heart. It’s a “whooshing” or “swishing” noise made by blood flowing through the heart’s chambers and valves.
The most important thing for parents to know is that the vast majority of heart murmurs in babies and children are completely harmless. This guide will help you understand the different types of murmurs, what causes them, and what to expect next.
In this article, you will learn:
- What a heart murmur is and what it sounds like
- The difference between a harmless (innocent) and a problematic (pathological) murmur
- The signs that might suggest a more serious issue
- How doctors evaluate a heart murmur
- What the next steps are for diagnosis and treatment
The Two Main Types of Heart Murmurs
Heart murmurs fall into two main categories. Understanding the difference is key to easing your worries.
1. Innocent (or Functional) Murmurs
This is by far the most common type. Up to 75% of children may have an innocent murmur at some point during their childhood.
An innocent murmur is simply the sound of normal blood flow moving through a normal, healthy heart. It does not mean there is anything wrong with the baby’s heart structure. These murmurs are common in newborns and young children because their hearts are growing rapidly.
An innocent murmur might be heard when:
- A baby is growing quickly.
- A child has a fever or is anemic, causing blood to flow faster.
- A child is excited or has just been very active.
Key takeaway: Innocent murmurs are harmless. They don’t require any treatment, diet changes, or restrictions on activity. Many disappear on their own as the child gets older.
2. Pathological (or Problematic) Murmurs
This type of murmur is much less common and indicates that there might be an underlying structural difference or problem with the heart. The extra sound is caused by abnormal blood flow due to this issue.
Common causes of pathological murmurs in babies include:
- A Hole in the Heart: A small opening in the wall separating the heart’s chambers. The most common types are an Atrial Septal Defect (ASD) or a Ventricular Septal Defect (VSD). The murmur is the sound of blood moving through this hole.
- Heart Valve Problems: A valve might be too narrow (stenosis), making it hard for blood to pass through, or it might not close properly and leak (regurgitation).
- Complex Congenital Heart Defects: In some cases, the murmur is a sign of a more complex combination of heart issues that the baby was born with.
Signs That May Accompany a Problematic Murmur
An innocent murmur usually has no other symptoms. However, if a murmur is pathological, you might notice other signs that the heart is working too hard.
Look out for these symptoms, especially in a newborn or infant:
- Poor feeding or getting tired during feedings
- Poor weight gain (failure to thrive)
- Rapid breathing or shortness of breath, especially while eating or sleeping
- Sweating during feeding
- A bluish tint to the skin, lips, or fingernails (called cyanosis)
- Swelling in the legs, abdomen, or around the eyes
If you notice any of these symptoms along with a known murmur, contact your doctor.
How Doctors Evaluate a Heart Murmur
If your pediatrician hears a murmur, they will start an evaluation to determine if it’s innocent or requires further investigation.
- Listening Carefully: An experienced doctor can often tell a lot about a murmur just by its sound. They listen for its loudness, timing (when it happens in the heartbeat cycle), and location in the chest. Many innocent murmurs have a distinct sound that doctors recognize.
- Referral to a Pediatric Cardiologist: If the doctor is unsure or if the murmur has characteristics that could be problematic, they will refer you to a pediatric cardiologist—a doctor who specializes in children’s heart conditions.
- Diagnostic Tests: The cardiologist will perform a painless, detailed evaluation, which usually includes:
- Echocardiogram (Echo): This is the most important test. It’s an ultrasound of the heart that uses sound waves to create moving pictures. It allows the doctor to see the heart’s structure, valves, and blood flow in detail. An echo can definitively confirm if the heart is normal (an innocent murmur) or if there is a problem.
- Electrocardiogram (ECG or EKG): This test records the heart’s electrical activity and can help detect rhythm problems or signs of stress on the heart muscle.
- Chest X-ray: This shows the size and shape of the heart and can reveal signs of fluid in the lungs.
What Happens Next?
The results of the evaluation will determine the next steps.
- If the murmur is innocent: The cardiologist will reassure you that your baby’s heart is healthy. No further action or follow-up is needed.
- If the murmur is pathological: The cardiologist will explain the specific cause and create a management plan. This can range from simply monitoring the condition (as many small holes close on their own) to prescribing medication or, in some cases, recommending a procedure or surgery to correct the problem.