Heart murmur in children: innocent murmurs, the heart scan and when to worry

A heart murmur in children is an extra whooshing sound the doctor hears through the stethoscope. Most of the time it comes from a normal heart. NUHS says about three in every ten children will have a heart murmur from time to time, and most of these are innocent murmurs. The American Academy of Pediatrics (AAP) says innocent murmurs need no treatment. Your doctor will tell you if a heart scan is needed to be sure.

What to do when the doctor hears a heart murmur, step by step

1. Ask the doctor if the murmur sounds innocent, and write down what they say. NUHS says other murmurs make a different sound and are usually easy to tell apart.
2. Mention any fever or recent illness. NUHS says innocent murmurs get louder with a fever, so ask if the doctor wants to listen again once your child is well.
3. Tell the doctor about feeding and weight, and bring the Child Health Booklet along. Johns Hopkins says a child with an innocent murmur has no symptoms besides the sound itself.
4. Ask for a referral letter if the doctor wants a specialist to check. KKH gives Singapore Citizens and PRs subsidised rates when a polyclinic or a CHAS GP refers them. Walk-in patients pay non-subsidised rates.
5. Book the paediatric cardiology clinic at KKH or NUH with that letter. NUH's heart team sees children for murmurs, palpitations, chest pain and fainting.
6. Get your child ready for the heart scan. NUH says young children may be given sedation if they need help keeping still. Our guide to preparing your child for hospital has ways to explain it.
7. Ask what the result means for sport and dental visits. For an innocent murmur, NUHS says your child can take part in all activities and sports, with no more check-ups needed.
8. Share the doctor's answer with your helper and the grandparents, and show them the warning signs below.
9. Act on the red flags. Breathlessness, poor feeding, poor weight gain, fainting, chest pain or blue lips need a doctor, and some need 995 (see the list below).

Innocent heart murmur or a sign of a heart problem?

Blood moving through the heart makes small vibrations, and a murmur is the sound of them. NUHS compares it to the noise water makes as it comes out of a tap. With an innocent murmur, the heart is completely normal. Doctors also call it a vibratory, functional or Still's murmur, or a venous hum. They all mean the same thing.

Other murmurs come from a hole in the heart or a narrowed or leaky valve, NUHS says. The AAP puts these at under 1% of people. KKH says about 8 in every 1,000 babies are born with a heart defect, and that 95% of the time a murmur is just blood flowing through a normal heart.

A murmur can come and go. NUHS says it's louder with a fever because the heart beats faster and blood moves quicker. The AAP says excitement or stress can do it too. Mayo Clinic lists phases of fast growth, such as the teenage years, and exercise. That's why a murmur is often first noticed when your child sees the doctor for a fever. Johns Hopkins says doctors grade loudness from 1 (very faint) to 6 (very loud).

Only a doctor can tell which kind your child has. This table shows how the two usually differ.

Heart murmur in babies

Your baby's heart gets its first check before you leave hospital. KKH says all babies in Singapore are screened by doctors soon after birth for congenital problems, heart defects included. Some murmurs only become clear after 3 to 6 weeks, KKH adds. Because babies see a doctor for jabs and developmental checks in the first year, KKH says serious heart defects are rarely missed here. Our child health screening guide lists every check and when it's due.

A referral is more common in young babies. The AAP says paediatricians are more likely to refer a baby whose murmur shows up in the first 6 months. It also says a referral doesn't mean the murmur is abnormal.

At home, the signs worth watching are in feeding and growth. KKH says a baby with a significant defect may be breathless, blue or not feeding well. If you're unsure your baby is taking enough, a few days in our newborn feed and nappy log plus a weight check on the baby growth percentile calculator gives the doctor something concrete to look at.

What happens at the KKH or NUH heart clinic

KKH and NUH both run paediatric cardiology clinics. At NUH's first appointment, a paediatric cardiologist takes your child's history and does an examination. A heart scan may follow. KKH says the cardiologist can often tell from the exam alone whether a murmur matters. The simple tests are a chest X-ray and an ECG, which records the heart's electrical activity. If those are normal, KKH stops there and reassures you.

An echocardiogram, or echo, is the heart scan. Johns Hopkins says it uses ultrasound to look at the heart's structure and how it works, and calls it the most important test for murmurs. NUH says young children may get sedation to help them lie still. A favourite toy or video can help a small child through the wait.

If your child is having heart checks after Kawasaki disease, our Kawasaki disease guide covers that follow-up.

Prefer a private paediatrician? Our paediatrician map lists clinics across Singapore. KKH's subsidised rates need the polyclinic or CHAS GP referral, so ask for one first if cost matters.

Sport, school and daily life with an innocent murmur

An innocent murmur leaves your child's routine as it was. NUHS says these children don't have a heart problem, can take part in all activities and sports, and need no further check-ups. They don't need antibiotics before a dental visit either. The AAP says the same, and adds that no sports limits are needed.

The sound usually fades. NUHS says innocent murmurs get harder to hear as children grow, though they're often still heard in adults. So the school health team or a new doctor may hear it again later. KKH says most children the school health team picks up for a murmur have normal hearts. Keep the cardiologist's letter or report, and show it when asked.

If the murmur comes from a heart problem, the activity plan is the cardiologist's call. NUHS notes there are no published guidelines for children's activity levels, and it names CCA sport and NAPFA training as more intense. Ask the doctor what's safe before your child starts them.

When to see a doctor

See your GP, polyclinic or paediatrician soon if your child has a murmur and any of these:

• Shortness of breath (Johns Hopkins, KKH)
• Trouble feeding, or sweating while feeding (AAP)
• Poor weight gain (KKH)
• Tiring easily or trouble keeping up with exercise (Johns Hopkins)
• Dizziness or fainting (Johns Hopkins, NUH)

Call 995, or go straight to KKH Children's Emergency or NUH Children's Emergency, if your child has:

• Blue lips or bluish skin (Johns Hopkins, AAP)
• Rapid or irregular breathing (Johns Hopkins)
• Chest pain (Johns Hopkins)
• Passed out, or can't be woken (Johns Hopkins)

Johns Hopkins lists these as reasons to call an ambulance. KKH's advice is to call 995 in a medical emergency.

Frequently asked questions

What is an innocent heart murmur?

It's the sound of blood flowing through a normal heart. NUHS says the heart is completely normal and the murmur isn't a sign of heart disease, so there's nothing to treat and your child can join in all activities and sports.

Is a heart murmur in babies serious?

Usually not. KKH says 95% of the time a murmur is blood flowing through a normal heart. If the doctor suspects a defect, KKH refers the baby to a paediatric cardiologist. Breathlessness, poor feeding or poor weight gain need a doctor, and blue lips need 995.

When to worry about a heart murmur?

Look at how your child is, more than at the sound. Johns Hopkins says innocent murmurs come with no other symptoms. A doctor should see a child who feeds poorly, gets short of breath or sweats at feeds, or who has fainted. For chest pain, blue lips or passing out, call 995.

Can a heart murmur go away on its own?

Innocent murmurs often do. The AAP says many go away as a child grows, though some last into adulthood. Some small holes close too: KKH says small holes between the lower heart chambers close by themselves in 30% to 50% of cases, mostly in the first year.

Does my child need an echocardiogram for a heart murmur?

Not always. NUHS says a heart scan settles it when there's any doubt about whether a murmur is innocent. KKH says a cardiologist can often tell from the exam and stops at simple tests if they're normal. Your doctor decides.

Can my child do sports with a heart murmur?

Yes, with an innocent murmur. NUHS says these children can take part in all activities and sports. If the murmur comes from a heart problem, ask the cardiologist what's safe before PE, CCA or NAPFA training.