What is a baby heart murmur? (Should you worry?)

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Want to learn more about babies and heart murmurs?

You're in the right place 🙂

In this edition of Baby Schooling, you can expect to learn:

  • What are heart murmurs and what causes them?
  • What types of murmurs exist?
  • When should a you worry about a heart murmur in your baby?
  • What medications exist to treat murmurs?
  • And is any of this preventable?
what is a baby heart murmur

Our babies are so precious and fragile that often the mere thought of discovering anything out of the ordinary during a medical examination is enough to send most parents into a flat spin of panic and fear.

Finding out that your baby has a heart murmur can be a frightening experience.

What most parents might not know is that many babies experience a heart murmur at some point and, more often than not, it's nothing to worry about.

Before you let your imagination run away with you, let's take a closer look at heart murmurs.

What are heart murmurs really?

A heart murmur is essentially an “extra” sound made by the heart and is caused by turbulence in blood flow.

To better understand what a heart murmur is, let's take a look at the heart and how it works.

The heart has four separate chambers. The two upper chambers are called ventricles and the two lower chambers are known as the atria (singular: atrium). These four chambers are connected by four valves. The valves open and shut with each heartbeat, working like one way doors to control the amount of blood that is pumped into each chamber.

The sound we hear when listening to the heart, is actually the sound of the valves closing as they control the amount of blood flowing through the heart. As the valves close they make a “lub dub” sound.

What most of us think of as a literal, pulsing “heartbeat” is, in fact, the sound of these valves snapping shut as they regulate blood flow.

A heart murmur is an additional or unusual sound (often a whooshing or swishing) that occurs between heartbeats and is due to turbulent blood flow.

Here's a great video by Dr. Nita breaking down some heart murmur myths!

What causes heart murmurs?

Turbulent blood flow within the heart, and the resulting murmur, may be caused by a wide variety of reasons - ranging from harmless (increased activity levels) to severe (valve problems).

To better understand what causes a heart murmur, let's take a look at the two different types of heart murmurs.

Types of heart murmurs

Innocent heart murmur

It's estimated that a whopping 75% of all newborns experience innocent heart murmurs - so you're definitely not alone!

Innocent (or harmless) heart murmurs do not require any treatment. This type of heart murmur may be present in hearts without any structural defects and, as the name suggests, is usually nothing to worry about. Innocent heart murmurs usually resolve themselves and are eventually outgrown or, in some cases, are present throughout life without causing any additional health problems/risks.

Innocent heart murmurs are often brought on by conditions that “get the heart pumping”, so to speak, by causing increased or rapid blood flow through the heart. Common causes of harmless heart murmurs are:

  • Pregnancy

  • Exercise

  • Anemia

  • Overactive thyroid (hyperthyroidism)

  • Growth spurts

While there is no treatment necessary for this type of heart murmur, underlying causes which may lead to ill health (anemia, hyperthyroidism) should still be treated.

Abnormal heart murmur

This type of heart murmur is more serious and requires special considerations and treatment. Abnormal heart murmurs are caused by congenital heart defects (structural abnormalities) within the heart and may come with symptoms that are at times severe and debilitated.

Congenital heart defects that cause abnormal heart murmurs:

  • Holes in the heart

These may or may not be serious depending on size and position.

  • Abnormalities in the heart valves

The most common valve defects are: Stenosis (narrowing of the valves) - a condition in which blood has difficulty passing through the valves.

heart murmurs in newborn stats

Regurgitation - here, the valves fail to close properly, causing leaks.

Other types of abnormal heart murmurs are more common in older children and adults. These are often caused by infections or other health complications that lead to structural damage of the heart.

Some common structural heart abnormalities brought on by illness or ageing are:

Endocarditis

When bacteria from other body parts (commonly from the mouth or throat) enter the bloodstream and are delivered to the heart, infection of the valves and inner lining of the heart may result. Left untreated, endocarditis leads to damage and, eventually, destruction of the heart valves.

This condition most often occurs in people who have existing valve abnormalities.

Valve calcification

This commonly occurs with aging. In this condition, the valves may harden, thicken and become narrow. Depending on the severity of this condition, it may become considerably harder for blood to pass through the valves and flow into the heart, leading to blood flow turbulence and heart murmurs.

Rheumatic fever

A serious condition, which is typically caused by an untreated strep throat infection. Rheumatic fever is known to cause permanent valve damage, leading to interference with normal blood flow into the heart. Luckily, this condition is rarely seen in developed western countries today.

Heart murmur related symptoms

Innocent heart murmurs often don't have any symptoms as there are usually no risks or complications involved.

Similarly, and depending on the severity of the underlying heart or valve condition, abnormal heart murmurs might not have any symptoms other than the sound heard by a doctor during an examination.

When should you worry about heart murmurs? 

The following symptoms could be related to a heart condition and should be checked by your doctor:

  • Blue tinged skin, usually seen in the extremities and especially around the lips and fingertips

  • Sudden, unexplained weight gain or swelling

  • Shortness of breath

  • Poor appetite

  • Poor growth in babies and failure to thrive

  • Unexplained heavy sweating

  • A cough that doesn't go away

  • Pronounced and enlarged neck veins

  • Chest pain

  • Lethargy (low energy levels)

  • Dizziness

  • Fainting

How are heart murmurs diagnosed?

When a heart murmur is detected in your baby, the doctor will listen carefully to try to determine whether it's an innocent heart murmur or an abnormal heart murmur. If your doctor is unsure or suspects that the murmur may be abnormal due to accompanying symptoms, they will refer you to a pediatric cardiologist.

The pediatric cardiologist will again examine your baby and will likely order an electrocardiogram (also known as an ECG or EKG). This is a quick and painless procedure that will help to identify and assess any abnormalities within in the heart.

There are no risks associated with this procedure, although some people may experience a slight allergic reaction the adhesive agents used to stick the electrodes to various parts of the body (chest, shoulders and each leg).

How are heart murmurs treated?

Innocent heart murmurs don't usually warrant treatment. This is because there there is nothing wrong with the heart itself. Harmless heart murmurs caused by medical conditions (hyperthyroidism, fever, high blood pressure, etc) will go away all by themselves once the underlying cause is treated and rectified.

Abnormal heart murmurs sometimes do not require treatment either. When an abnormal heart murmur is not severe or is present without a severe or deteriorating cause, your doctor may choose to monitor the condition over time, watching closely for signs of complications.

Should treatment be required, the nature of the heart’s defects will determine the course of action necessary. Often, medication or surgery is needed and sometimes both.

Medications used to treat abnormal heart murmurs 

  • Anticoagulants/blood thinners

These help to thin the blood and work by preventing blood clots in heart and improving blood flow.

  • Diuretics/water pills

Water pills work by removing excess fluid from the body and are often used to treat conditions like high blood pressure, that are known to exacerbate heart murmurs.

  • Angiotensin-converting enzyme (ACE) inhibitors

These also help to lower blood pressure.

  • Statins

These lower cholesterol. This is important for types of heart murmurs affected by high cholesterol.

  • Beta blockers

Beta blockers lower heart rate and blood pressure, reducing the risk of complications associated with these factors.

Surgery for heart murmurs caused by damaged valves

Damaged or leaky valves often won't benefit from medication alone and your doctor may recommend one of the following surgeries.

  • Balloon valvuloplasty

Narrow valves may be treated by the insertion of a tiny balloon within the valve, which is then expanded to widen the valve.

  • Annuloplasty

When leaky valves are caused by abnormal openings, an artificial ring is inserted to ensure proper closure of valve flaps.

  • Valve flap/leaflet repair

In defective valves where the leak or blockage is caused by the flap itself, doctors will surgically separate, cut or pleat the valve.

  • Structural support repair

In order to prevent leaks and aid blood flow to the heart, it's important that the valves have the correct structural support. In cases where heart murmurs are caused by structural defects, surgeons are able to shorten or even replace the cords that support the valves, helping to ensure that the edges of the valve flaps meet.

Can you prevent heart murmurs?

While heart murmurs themselves cannot be prevented, innocent heart murmurs are common and usually resolve themselves. The causes of more serious abnormal heart murmurs can be treated by the methods mentioned above which will result in the reduction (and sometimes, elimination) of the heart murmur itself. 

We hope that reading this article has brought you a little closer to understanding the nature of a heart murmur.

With so much negativity surrounding heart murmurs, it's easy to become fearful and anxious at the mention of them - especially when it concerns your baby. It's important to remember that most babies and children naturally experience heart murmurs at some point and this doesn’t necessarily mean that there's anything wrong with your child. Even if your child does have an abnormal heart murmur, chances are that with the right care they will still be able to lead a happy and healthy life.

Take a deep breath, mama. Now let it out and do it again! Being responsible for the life of another is the scariest job in the world and is full of unexpected twists and turns.Just know that you'll get through it, no matter what - you're a mother,afterall!

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