Pediatric Cardiology • Parent Guide
Heart Murmur in Children
One of the most common reasons children are referred to a paediatric cardiologist — and in the vast majority of cases, completely reassuring news.
📚 Moss & Adams, 10th Ed. | Rudolph’s Congenital Diseases of the Heart, 3rd Ed. | ACC/AHA Guidelines
👨⚕️ Pediatric Cardiology
KEY STATS
| ~80% | 1 in 3 | 0 | ♥ Normal |
|---|---|---|---|
| Of childhood murmurs are innocent (harmless) | Children will have an innocent murmur heard at some point | Extra risk from innocent murmurs | Innocent murmurs require no treatment or restriction |
🫀 What Is a Heart Murmur?
A heart murmur is simply a sound made by blood flowing through or near the heart. It is heard with a stethoscope as a “whooshing,” “swishing,” or blowing sound — in addition to or between the normal “lub-dub” heartbeats.
A murmur is not a diagnosis. It is a physical finding — like a blood pressure reading or a breathing rate. The critical question is: what is causing it?
The cause is almost always one of two things:
- Normal blood flow through a normal heart — an innocent murmur
- Abnormal blood flow through a structural heart defect — a pathological murmur
💡 Why Do Innocent Murmurs Exist?
Children have faster heart rates, thinner chest walls, and higher cardiac output (more blood pumped per minute relative to body size) than adults. All of this means normal blood flow through a normal heart can create audible turbulence — a sound. This is completely harmless. It is a sound, not a structural problem. The heart is working exactly as it should — it just happens to be noisy about it in this child, at this time.
Innocent vs. Pathological Murmurs — Key Differences
| Feature | Innocent Murmur | Pathological Murmur |
|---|---|---|
| Loudness | Usually soft (grade 1–2/6) | Often louder (grade 3/6 or with thrill) |
| Quality | Musical, vibratory, soft | Harsh, blowing, high-pitched |
| Timing | Systolic only (between heartbeats) | Can be systolic, diastolic, or continuous |
| Location | Left sternal border, variable | Specific location based on defect |
| Changes with position | Decreases or disappears when lying flat | Usually unchanged |
| Radiation | Minimal | May radiate to axilla, back, neck |
| Other sounds | S1 and S2 normal; no clicks or extra sounds | May have abnormal S2, clicks, or extra sounds |
| Child’s growth | Normal | May be poor |
| Exercise tolerance | Normal | May be reduced |
| ECG/Echo | Normal | May be abnormal |
The Common Innocent Murmurs in Children
1. Still’s Murmur (Most Common — 3–7 years)
A low-pitched, musical, vibratory systolic murmur heard best at the lower left sternal border. Often described as sounding like a “twanging string.” Decreases or disappears when the child sits up or lies down. Almost always disappears by adolescence. Named after Sir George Frederick Still. No treatment, no restriction, no follow-up needed once confirmed.
2. Pulmonary Flow Murmur
A soft systolic ejection murmur heard at the upper left sternal border. Common in active children, anaemia, fever, or anxiety — any state of high cardiac output. Disappears with the underlying cause. Very common in teenagers, especially girls.
3. Venous Hum
A continuous murmur heard below the clavicles (collarbone) on both sides. Caused by blood flowing in the large veins of the neck returning to the heart. Disappears completely when the child lies flat or when gentle pressure is applied to the neck veins. This is the only innocent murmur that is continuous (not just systolic).
4. Peripheral Pulmonary Stenosis (Newborns)
A soft systolic murmur heard in the axillae and back of a newborn — caused by the relative narrowness of the branch pulmonary arteries in the first weeks of life. Resolves spontaneously by 6–8 weeks as the vessels grow. Very commonly causes parental anxiety and unnecessary referrals when the natural history is known.
⚠️ Warning Signs That a Murmur Needs Further Evaluation
Refer urgently if the murmur is accompanied by:
– Bluish lips or tongue (cyanosis)
– Rapid or laboured breathing
– Poor weight gain or feeding difficulty
– Exercise intolerance — tiring much faster than peers
– Chest pain or syncope (fainting)
– Abnormal ECG or X-ray
– A diastolic component (all diastolic murmurs in children should be evaluated)
– A palpable thrill (vibration felt with the hand on the chest)
– A loud murmur, grade 3/6 or more, with a harsh quality
🔧 Do All Murmurs Need an Echocardiogram?
Not all — but it depends on the clinical picture.
An experienced paediatric cardiologist can diagnose an innocent murmur by examination alone with very high accuracy. If the clinical history, examination, and ECG are all normal and the murmur has typical innocent features — an echocardiogram may not be necessary.
However, an echocardiogram is appropriate when:
- The murmur has any atypical features (diastolic, continuous, loud, harsh)
- The child has symptoms
- The examining doctor is uncertain
- There is parental anxiety that warrants clear reassurance with imaging
- The child is about to participate in competitive sports
- There is a family history of CHD
An echocardiogram is completely safe (ultrasound, no radiation) and provides definitive structural information. When in doubt — it is always the right test to request.
Grading of Murmurs (Levine Scale)
| Grade | Description |
|---|---|
| 1/6 | Very soft — heard only in a quiet room by an experienced listener |
| 2/6 | Soft but readily audible |
| 3/6 | Moderately loud — no thrill |
| 4/6 | Loud — thrill present |
| 5/6 | Very loud — heard with stethoscope barely touching chest |
| 6/6 | Heard without stethoscope |
Innocent murmurs are nearly always grade 1–2. A grade 3 or above always warrants further evaluation.
❓ Frequently Asked Questions
Q: The doctor said my child has an innocent murmur — can I truly relax?
Yes. An innocent murmur confirmed by an experienced clinician (and an echo if done) means the heart is structurally and functionally completely normal. There is nothing wrong. The murmur is a sound, not a disease. Your child needs no treatment, no restrictions, no special diet, and no follow-up specifically for the murmur. They can play sport, run, swim, and live entirely normally.
Q: Will the murmur go away?
Many innocent murmurs — particularly Still’s murmur — become softer or disappear entirely as the child grows into adolescence. This is because the chest wall thickens, heart rate slows, and relative cardiac output decreases. However, some innocent murmurs persist into adulthood without ever causing any problem. Whether it stays or goes doesn’t change anything — an innocent murmur is harmless regardless.
Q: My child’s school asked for a “cardiac fitness certificate” — what do I do?
If an echocardiogram has confirmed a structurally normal heart, your cardiologist can issue a fitness certificate confirming there is no cardiac reason to restrict sports participation. This is routine and straightforward. If the murmur has not yet been evaluated by echo, the evaluation should be done before clearance is given.
Q: What if it’s not innocent — what then?
If the echo shows a structural defect (like a small VSD or bicuspid aortic valve), your cardiologist will explain exactly what was found, what it means, and whether any treatment or monitoring is needed. Many structural defects found incidentally are minor and require only periodic echo follow-up. The fact that it was found early is always better than finding it later.
Q: Can a murmur develop later in childhood even if it wasn’t there at birth?
Yes. Some structural defects (like bicuspid aortic valve or small VSDs) may not produce audible murmurs until the child is older. Innocent murmurs also commonly appear for the first time during childhood or during illness (fever, anaemia), because high cardiac output states make murmurs louder. A new murmur heard at age 5 that wasn’t present at birth is not necessarily alarming — but it should be evaluated.
Q: Could my child have a murmur and still have a serious undetected condition?
This is rare but possible — which is why paediatric cardiologists take murmur evaluation seriously rather than dismissing every murmur as innocent without examination. A careful clinical assessment by a trained paediatric cardiologist, with an echocardiogram when indicated, reliably identifies those that need attention. If you have residual concern after evaluation, it is always acceptable to ask for the echo.
🎯 Key Takeaways
- A heart murmur is a sound, not a diagnosis — it means blood flow is audible, not necessarily that something is wrong.
- Approximately 80% of childhood murmurs are innocent — the heart is completely normal.
- Innocent murmurs are soft, musical, systolic, and change with position. They require no treatment and no restriction.
- Red flags that need evaluation: loud or harsh murmur, diastolic murmur, palpable thrill, cyanosis, poor weight gain, exercise intolerance.
- A paediatric cardiologist can diagnose innocent murmurs clinically; an echocardiogram confirms when there is doubt.
- A confirmed innocent murmur means your child is fine — no follow-up for the murmur is needed.
📚 References & Sources
Rudolph AM. Congenital Diseases of the Heart, 3rd Edition. Wiley-Blackwell, 2009.
Allen HD et al. Moss & Adams’ Heart Disease in Infants, Children, and Adolescents, 10th Ed. Wolters Kluwer, 2022.
Advani N, Menahem S, Wilkinson JL. The diagnosis of innocent murmurs in childhood. Cardiol Young 2000;10(4):340–342.
© PedHeartIndia | www.pedheartindia.com — Educational purposes only.
A note from Dr. Sunil: This article is general educational information and is not a substitute for personal medical advice. For any concern about your child’s heart, please see a qualified doctor in person.
