Heart Murmurs in Children

Why is this topic important?

Heart murmurs are one of the commonest reasons for referral to paediatric clinics and paediatric cardiology services.

MRCPCH candidates are frequently expected to:

Recognise innocent and pathological murmurs
Understand murmur characteristics
Identify red flag features
Recognise common congenital heart lesions
Decide which children require urgent referral

A systematic approach to heart murmurs is essential for both examinations and clinical practice.

Definition

A heart murmur is an additional sound produced by turbulent blood flow within the heart or great vessels.

Murmurs may be:

Innocent (physiological)
Pathological (associated with structural heart disease)

The majority of childhood murmurs are innocent.

Key MRCPCH Facts

Most childhood murmurs are innocent.
An asymptomatic child with a soft murmur is more likely to have an innocent murmur.
Diastolic murmurs are always abnormal until proven otherwise.
Loud murmurs are more likely to be pathological.
Cyanosis, heart failure or abnormal pulses suggest structural heart disease.
A normal cardiovascular examination does not completely exclude congenital heart disease.
Murmurs should always be interpreted alongside the clinical picture.

Pathophysiology

Why Do Murmurs Occur?

Blood flow is normally smooth (laminar).

Murmurs occur when blood flow becomes turbulent.

Causes include:

Increased flow across a normal valve
Narrowed valves or vessels
Abnormal communications between chambers
Regurgitant valves

Classification of Murmurs

Innocent Murmurs

Occur in structurally normal hearts.

Caused by normal blood flow.

Pathological Murmurs

Result from structural heart disease.

Examples:

Ventricular Septal Defect (VSD)
Aortic Stenosis
Pulmonary Stenosis
Patent Ductus Arteriosus (PDA)
Tetralogy of Fallot (TOF)

Characteristics of Innocent Murmurs

A useful MRCPCH concept is:

The Seven S's

Innocent murmurs are usually:

Soft
Systolic
Short
Single
Small area
Sweet sounding
Sensitive to posture

Common Innocent Murmurs

Still's Murmur

Most common innocent murmur.

Characteristics:

Vibratory or musical
Low frequency
Left lower sternal edge
Usually age 2–7 years

Pulmonary Flow Murmur

Characteristics:

Soft ejection systolic murmur
Upper left sternal edge
Common in older children

Venous Hum

Characteristics:

Continuous murmur
Changes with neck position
Disappears when lying down

Characteristics Suggesting a Pathological Murmur

Murmur Features

Loud murmur (Grade 3 or more)
Diastolic murmur
Continuous murmur (except venous hum)
Harsh quality
Thrill present
Radiation to back or neck

Associated Clinical Features

Cyanosis
Poor feeding
Failure to thrive
Tachypnoea
Hepatomegaly
Abnormal pulses
Low oxygen saturation

These features require urgent assessment.

Clinical Assessment

History

Ask about:

Neonates

Feeding difficulties
Sweating during feeds
Tachypnoea
Cyanosis

Older Children

Exercise intolerance
Chest pain
Syncope
Palpitations

Family History

Important conditions include:

Congenital heart disease
Sudden cardiac death
Cardiomyopathy

Examination

General Inspection

Look for:

Cyanosis
Respiratory distress
Failure to thrive

Pulse Assessment

Assess:

Rate
Rhythm
Volume
Radiofemoral delay

Blood Pressure

Measure if coarctation suspected.

Precordium

Assess for:

Heaves
Thrills
Displaced apex beat

Auscultation

Determine:

Timing
Intensity
Location
Radiation
Additional heart sounds

Murmur Grading

Grade 1

Very soft.

Grade 2

Soft but easily heard.

Grade 3

Moderately loud.

Grade 4

Loud with palpable thrill.

Grade 5

Very loud.

Grade 6

Audible without stethoscope fully touching chest.

MRCPCH candidates should know that thrills usually indicate significant pathology.

Common Murmurs in Congenital Heart Disease

Ventricular Septal Defect

Pansystolic murmur
Left lower sternal edge

Patent Ductus Arteriosus

Continuous machinery murmur
Left infraclavicular area

Pulmonary Stenosis

Ejection systolic murmur
Upper left sternal edge

Aortic Stenosis

Ejection systolic murmur
Right upper sternal edge
Radiates to neck

Tetralogy of Fallot

Ejection systolic murmur
Upper left sternal edge

Investigations

Pulse Oximetry

Useful in infants.

ECG

May demonstrate chamber hypertrophy or arrhythmias.

Chest X-Ray

Sometimes useful but not always required.

Echocardiography

Gold standard investigation.

Provides:

Structural diagnosis
Haemodynamic assessment
Treatment planning

Management

Innocent Murmurs

Reassurance
No treatment required
No activity restriction

Pathological Murmurs

Management depends on underlying diagnosis.

May include:

Medical management
Cardiology follow-up
Interventional procedures
Surgery

Complications

Complications depend on the underlying lesion.

Potential complications include:

Heart failure
Pulmonary hypertension
Arrhythmias
Cyanosis
Growth failure

Common Exam Traps

Trap 1

Most childhood murmurs are innocent.

Trap 2

Diastolic murmurs are always abnormal.

Trap 3

A thrill usually indicates pathology.

Trap 4

A loud murmur is not always a severe lesion.

Trap 5

Small VSDs may produce louder murmurs than large VSDs.

Trap 6

Always assess the child, not just the murmur.

One Minute Revision

Most murmurs in children are innocent.
Innocent murmurs are soft and systolic.
Diastolic murmurs are pathological.
Thrill = likely structural heart disease.
Cyanosis, heart failure and abnormal pulses are red flags.
Echocardiography is the gold standard investigation.
Always assess the whole child.

Suggested References

NICE Guidance
RCPCH Guidance
BNF for Children
Nelson Textbook of Pediatrics
Illustrated Textbook of Paediatrics
Park's Pediatric Cardiology for Practitioners
Moss & Adams' Heart Disease in Infants, Children and Adolescents

Disclaimer

These notes are intended for MRCPCH revision and educational purposes only. They do not replace local, national or institutional guidelines. Clinical decisions should always be based on current guidance, senior advice and individual patient circumstances.

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