With thanks to Dr Tom Waterfield for his work on this article as part of our series on the 6 week baby check…

The assessment of murmurs can be difficult and identification of the underlying pathology, if any, is best left to a specialist.  For the purpose of the 6 week screening test all murmurs should be referred for further assessment but it is important to identify those children that require urgent assessment from the vast majority that simply require re-assurance and routine referral to a general paediatrician or paediatric cardiologist.

A hypothetical model of heart murmurs in children aged 1 month to 18 years done by an NHS economic evaluation team (http://www.crd.york.ac.uk/CRDWeb/ShowRecord.asp?ID=22002001874) suggested that only approximately 2% of these murmurs would be due to an underlying structural anomaly.   I think the wide age range might undermine this statistic’s relevance to the 6 week check cohort of babies.  A more widely quoted reference from 1998 reports that of 50 healthy term babies with heart murmurs, in 64% the murmur had disappeared by 6 weeks of age.  None of the babies had clinically significant congenital heart disease  and had all disappeared by 6 months of age but one baby had developed a different innocent murmur!  Read the full text of this paper at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1720793/pdf/v078p0F166.pdf.

If a murmur is detected it is important to consider the likelihood of there being significant underlying disease before referring for further assessment and before discussing the murmur with the parents. 

Innocent murmurs are common in children and are associated with normal weight gain, normal feeding and an otherwise normal clinical examination. 

The key points of clinical assessment include:

1)      Assessment of the murmur

1. Location on the precordium e.g. left sternal edge (Common site of innocent murmurs)
2. Intensity (1/6 = almost inaudible, 3/6 = audible with a stethoscope, 6/6 easily audible without a stethoscope and associated with a palpable thrill).  Murmurs are more often described now as soft or loud, harsh or musical.
3. Variability with position – a feature of innocent murmurs (but not something one necessarily notices at the 6/52 check)
4. Diastolic Vs Systolic – diastolic murmurs should always be treated as pathological

2)      Assessment of perfusion

1. A pink child with a capillary refill time <2 seconds and with good peripheral pulses (including femoral pulses) is less likely to have significant heart disease
2. Absent femoral pulses may represent coarctation of the aorta
3. Cyanotic heart lesions rarely present outside the immediate perinatal period 

3)      Assessment for signs of heart failure

1. Failure to thrive and recurrent respiratory infections
2. Respiratory distress with hepatomegaly.  Crackles are not really heard in heart failure in infants
3. Peripheral oedema and a raised JVP are NOT features of heart failure in this age group and their absence is not reassuring

If a child has a soft systolic murmur at the 6 week check and is growing well and feeding normally with an otherwise normal examination the child can be referred routinely to paediatric outpatients and the parents reassured that the murmur is likely to be due to the normal flow of blood around the heart.  If there are any worrying features then the child should ideally be discussed with the paediatric registrar on call and the appropriate referral or admission discussed.

References

The British Heart Foundation has a factfile sheet for GPs on heart murmurs in children but it is not downloadable from http://www.bhf.org.uk because it is over 5 years old and they worry that their old factsheets may go out of date.  BHF have however very kindly sent it to me and allowed me to upload it on to this site as an educational resource.  Download it here.

http://www.patient.co.uk/doctor/Heart-Murmurs-in-Children.htm would be a good resource except that it still talks about antibiotics for children with heart defects when they have dental treatment and we gave up doing that in 2008 after NICE said it wasn’t necessary (http://www.nice.org.uk/nicemedia/live/11938/40014/40014.pdf).

http://www.tinytickers.org is a parental support website concerned primarily with antenatal diagnosis and screening.

http://kidshealth.org/parent/medical/heart/murmurs.html# is one of the top American sites on children’s health aimed at the general public.  It provides balanced information in clear English about heart murmurs for parents who are worried that their GP has picked up a heart murmur incidentally on examining their child.  Our outreach cardiologist has written a few words on innocent heart murmurs too at http://www.kidscardiologist.com/conditions/innocent-murmur.html.

If your patient does turn out to have congenital heart disease, http://www.rch.org.au/cardiology/defects.cfm?doc_id=3011 is a fantastic site from Melbourne’s Royal Children Hospital with lovely clear diagrams and explanations of different morphological anomalies.