oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
See also separate article Heart auscultation.
Heart murmurs are due to abnormalities of flow within the heart and great vessels. Innocent murmurs are very common but it is essential to assess whether the murmur is haemodynamically significant and whether appropriate antibiotic prophylaxis to prevent endocarditis is required. If there is any doubt, referral to a general paediatrician or paediatric cardiologist is essential.
The following make heart murmurs more likely:
- Maternal alcohol or drug exposure to fetus.
- Maternal diabetes.
Murmurs are described by location, intensity (grade 1-6 with grade 1 being virtually undetectable), timing in the cardiac cycle, and radiation.
The absence of symptoms does not exclude important pathology. Certain features indicate that a murmur is more likely to be pathological and that prompt expert evaluation is needed:
- History: lethargy, tiredness, failure to thrive.
- Inspection: cyanosis, clubbing, abnormal breathing (tachypnoea, intercostal recession).
- Palpation: parasternal or apical impulse; abnormal pulses - diminished, absent or delayed femoral pulses.
- Abnormal heart sounds; second heart sound is accentuated and not variably split.
- Systolic murmur which is pansystolic or is grade 3 or above.
- Murmur which is purely diastolic.
- Radiation of murmur to the back.
- Presence of an early or midsystolic click.
- Presence of cardiac failure or arrhythmia.
- Innocent murmurs are common in children and tend to become audible or louder when the heart beats faster, such as with a raised temperature or excitement.
- Still's murmur (or Fiddle string murmur) is the most common innocent murmur heard in children aged 2 to 8 years old. It is a short, midsystolic murmur with a very characteristic low-frequency buzzing or musical quality. It is localised to the lower left mid-sternal border and radiates to the apex. The murmur is of short duration, low intensity and is loudest when the child is supine, often varying markedly with posture. It is also provoked by fever and anaemia. It can be made to disappear on hyperextension of the back and neck (Scott's manoeuvre). However, it is not always possible to distinguish it from a small ventricular septal defect. Still's murmur usually disappears at puberty.
- The venous hum is a superficial continuous murmur heard beneath the clavicles and in the neck. It is more often heard in the right than left side and most easily when the child is upright. It can be abolished by head movements, by compression of the jugular vein on the same side, or by the child lying supine.
- Pulmonary flow murmur is a soft early-to-mid systolic ejection murmur heard at the upper left sternal border but does not radiate to the back. In premature and newborn infants, an innocent soft ejection murmur can be heard at the base with radiation into the axillae and even the back. This originates in the proximal pulmonary artery branches. It disappears before 1 year of age.
- Apical murmur: localised, apical, high-pitched midsystolic murmur.
- Innocent carotid bruits are common in normal children. It is midsystolic and is best heard in the neck just above the clavicle, often radiating down to the aortic area. Aortic stenosis is differentiated by its murmur being louder below the clavicle than above.
Pathological systolic murmurs
See also separate article Congenital heart disease in children.
- Ejection systolic murmurs: reach a peak midway between 1st and 2nd heart sounds and don't run into the 2nd heart sound. Usually maximal at the upper sternal borders, and possible causes include:
- Aortic stenosis.
- Pulmonary stenosis.
- Coarctation of the aorta: murmur is heard over the back, particularly in the interscapular region.
- Hypertrophic obstructive cardiomyopathy.
- Pansystolic murmurs have uniform intensity between 1st and 2nd heart sounds and merge with the 2nd heart sound, which is therefore not distinguishable. Those at the lower sternal border are more likely to be of regurgitant type due to:
- Ventricular septal defect.
- Atrial septal defect.
- Mitral or tricuspid regurgitation.
- Diastolic murmurs should always be regarded as pathological.
- Early diastolic murmurs: occur just after the 2nd heart sound. They are high-pitched and easily missed. Causes include aortic valve regurgitation (eg bicuspid aortic valve, Marfan's syndrome) and pulmonary valve regurgitation (eg following surgery for Fallot's tetralogy or pulmonary stenosis), or with pulmonary hypertension.
- Mid or late diastolic murmurs: are low-pitched and occur at the lower sternal borders in mitral stenosis or tricuspid stenosis.
These cross the 2nd heart sound and are a feature of:
- Venous hum (otherwise they are always pathological).
- Persistent ductus arteriosus.
- Arteriovenous malformation.
- CXR, ECG and echocardiogram are often performed but add little or no information in a child clinically assessed to have an innocent murmur.
- Neonatologists and paediatric cardiologists are equally effective in diagnosing cardiac pathology.
- An echocardiogram is the the gold standard for the diagnosis of a structural heart disease but is not routinely required. Older toddlers who are asymptomatic when referred for echocardiogram, are rarely found to have serious pathology.
- Cardiac catheterisation is occasionally necessary.
- Unless obviously an innocent flow murmur, referral to a general paediatrician or paediatric cardiologist is essential.
- Antibiotic prophylaxis will be required for some causes of heart murmurs.
Further reading & references
- Children's Heart Federation; Children's Heart Federation
- Frank JE, Jacobe KM; Evaluation and management of heart murmurs in children. Am Fam Physician. 2011 Oct 1;84(7):793-800.
- Still's Murmur - sound file; Still's Murmur - sound file (mp3)
- Azhar AS, Habib HS; Accuracy of the initial evaluation of heart murmurs in neonates: do we need an Pediatr Cardiol. 2006 Mar-Apr;27(2):234-7.
- Kwiatkowski D, Wang Y, Cnota J; The utility of outpatient echocardiography for evaluation of asymptomatic murmurs Congenit Heart Dis. 2012 May;7(3):283-8. doi: 10.1111/j.1747-0803.2012.00637.x.
- NHS Economic Evaluation Database; Evaluation of heart murmurs in children: cost-effectiveness and practical implications.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Colin Tidy
Dr Hayley Willacy
Dr Hannah Gronow