Newborn Heart Health: S3 Murmur Normal?

An S3 murmur is a type of heart murmur, which is the name for abnormal sounds caused by irregular blood flow. Murmurs can be caused by something as simple as blood moving too fast, or by a structural issue with the heart. Heart murmurs in newborns are common, and many are harmless, but they can also be a sign of a dangerous disorder. An S3 murmur in a newborn is a normal occurrence and is not necessarily indicative of a heart defect. However, it is important to follow up with a paediatrician to ensure the murmur is thoroughly evaluated.

What is an S3 murmur?

An S3 murmur, also known as a "ventricular gallop", is a low-frequency sound that occurs just after the second heart sound, or "dub", (S2) in early diastole. It sounds like "Lub du bub S1S3S2" and is similar to the word "Kentucky".

An S3 murmur is caused by a large amount of blood striking a very compliant left ventricle (LV). It is a normal physiological finding in patients under 40 and is often a sign of systolic heart failure. It can also be caused by increased atrial pressure leading to increased flow rates, as seen in congestive heart failure, which is the most common cause of an S3 murmur.

Dilated cardiomyopathy with dilated ventricles can also contribute to the sound. Less commonly, valvular regurgitation and left-to-right shunts may also result in an S3 murmur due to increased flow.

An S3 murmur is graded as a 5 or 6 on the heart murmur grading scale, meaning it can be felt by putting a hand on the chest over the heart.

How common are heart murmurs in newborns?

Heart murmurs in newborns are extremely common and often harmless. Two-thirds of children and about three-quarters of newborns have a heart murmur. A 2022 study found that up to 8.6% of infants and 80% of children have a heart murmur.

Heart murmurs are abnormal sounds (like whooshing, rasping, or swishing) caused by irregular blood flow. They can be heard between regular beats or as changes in the beats themselves. Murmurs can occur when blood moves too fast or when there is a structural issue with the heart.

Newborns often have heart murmurs, but congenital heart diseases are a concern at this age. While most newborn murmurs are innocent, it is important to follow up with a pediatrician to ensure the murmur is thoroughly evaluated. If a heart murmur persists, a referral to a pediatric cardiologist may be necessary.

There are two main types of heart murmurs: innocent heart murmurs and abnormal heart murmurs. Innocent heart murmurs are very common in healthy infants, children, and teens. They are typically caused by quick and rapid blood flow combined with smaller-than-normal blood vessels. As the baby grows, these blood vessels also grow, and the murmurs usually disappear without treatment. Abnormal heart murmurs, on the other hand, are caused by structural issues within the heart, such as stenosis, regurgitation, or vessel outflow/tract narrowing.

In summary, heart murmurs in newborns are very common, with up to 80% of newborns exhibiting this condition. Most of these murmurs are innocent and disappear without treatment. However, it is important to monitor them and seek medical advice to rule out any underlying heart conditions.

What are the symptoms of a newborn heart murmur?

It's important to note that most newborn heart murmurs are innocent and often harmless. However, some heart murmurs may indicate underlying conditions that require monitoring or treatment. Here are the symptoms of a newborn heart murmur:

• Slow or delayed growth
• Cyanosis, which is a blue colouration of the extremities or lips
• Respiratory distress
• Sweating during feedings
• Poor appetite and lack of growth
• Bluish skin, especially on the lips and fingertips
• Swelling or sudden weight gain
• Frequent chest infections
• Difficulty breastfeeding or eating
• A blue tint to the lips and skin (cyanosis)

If you notice any of these symptoms in your newborn, it is important to consult a paediatrician or a paediatric cardiologist for further evaluation and appropriate treatment.

How are newborn heart murmurs diagnosed?

Heart murmurs in newborns are usually diagnosed by a doctor using a stethoscope to listen to the heart. The doctor will be listening for the typical "lub-dub" sound of the heart valves closing, as well as any abnormal sounds such as whooshing, rasping, or swishing, which could indicate a heart murmur. Murmurs can be graded from 1 to 6 depending on how loud they are; the quieter ones can be harder to detect, so it is helpful for the child to be quiet during the examination.

If a murmur is detected, the doctor may refer the child to a pediatric cardiologist for further assessment. The cardiologist may order diagnostic tests such as an echocardiogram (a specialised ultrasound of the heart), an electrocardiogram (which measures the heart's electrical activity), or a chest X-ray to visualise the heart and surrounding organs.

Heart murmurs are very common in newborns, with up to 8.6% of infants and 80% of children having one, and they are often harmless. However, it is important to follow up with a doctor to ensure the murmur is not a sign of an underlying condition.

What is the treatment for a newborn heart murmur?

Heart murmurs in newborns are extremely common and often harmless. Murmurs are graded on a scale of 1 to 6, based on how loud they are. One means a very faint murmur, while six means a very loud murmur that can be felt by putting a hand on the chest over the heart.

The treatment for a newborn heart murmur depends on the type of murmur. Innocent murmurs, which are not related to structural issues in the heart, often resolve on their own as the child grows and blood vessels and organs get bigger, allowing for smoother blood flow. Pediatricians and pediatric cardiologists will continue to monitor the murmur during the child's annual checkups.

The treatment of abnormal heart murmurs can be more complex and depends on the type and severity of the murmur. In some cases, structural heart issues can resolve on their own, so doctors may recommend monitoring the situation before taking steps to treat the murmur. However, if the murmur poses a risk to the child's health, surgery may be necessary to treat the underlying heart disease or condition causing the murmur.

If there are signs of a pathological murmur, such as frequent chest infections, difficulty breastfeeding or eating, sweating while eating, or a blue tint to the lips and skin (cyanosis), it is important to consult a pediatric cardiologist for further evaluation and treatment.

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