Tuesday, 8 August 2017

Heart Murmurs in Children

Heart murmurs are a reasonably common finding in children.  Excluding the newborn and early infancy assessments, most of the murmurs that we hear are benign, physiological or flow murmurs.  All of those terms basically mean the same thing – the anatomy is normal, the child is healthy and yet there is an extra noise heard on auscultation of the heart.  The reason that this usually occurs is that children’s physiology responds vigorously to illness and stress.  The heart pumps faster and harder, often making a structurally normal heart into a noisy heart.

In short, heart murmurs are almost always nothing to worry about.  Almost.

The trouble is that everything in paediatrics has an evil twin.  So what are the possible more significant  pathologies and how can these be recognised amongst the far more common benign diagnoses?  When children present with an acute illness, a cardiac cause for their symptoms is not usually top of our list of differential diagnoses because respiratory and musculoskeletal cases are far more common reasons for chest pain or dyspnoea.  This coupled with the way that cardiac problems present (with vague symptoms easily attributable to more common illnesses) make these rare clinical scenarios into the stuff of our worst fears.


Let’s look at a few made up cases to illustrate how to approach the “Oooh-I’ve-heard-a-murmur-what-now?” scenario.

Case 1

A 3 year old child presents with a febrile illness.  Let’s say that they have an otitis media.  They have a heart rate at the top of the reference range for their age and you hear a murmur.  The murmur is soft, easily heard (but not loud), systolic and heard best at the left sternal edge.  There is no radiation.

What now?

In primary care, we are all about the focussed history and examination.  We have to be in order to make time for our other patients.  That ergonomic approach works well, but when we find something that we weren’t expecting, we need to go back and get more information.  In this case, we want to know if the child is known to have a heart murmur.  Have they had an echo done in the past?  We also need to feel the precordium for heaves and thrills and be happy that the pulses have a normal character and volume.  Make sure that the femoral pulses are palpable, with no brachio-femoral delay.  Check for hepatomegaly.  Most importantly, make sure that the child does not have increased work of breathing and does not seem unexpectedly unwell.  Ideally, we need to get a blood pressure checked.

What next?

We need to refer a child with a murmur acutely (usually to general paediatrics) if

  • they are more unwell than expected
  • they have respiratory symptoms which are otherwise unexplained
  • there are concerning clinical examination finding (e.g. hepatomegaly)

A well child with none of the above ‘red flags’ probably needs an outpatient echo if

  • The murmur is loud
  • The murmur is diastolic
  • The murmur radiates outside of the precordial area

If the child is well, there are no red flags and the murmur sounds benign (as in the original description for this case) then common practice is to follow the child up when they are well again.  The presumption is that this is a physiological murmur which has been heard because the illness is causing increased cardiac output and therefore turbulent blood flow.

It is likely that when they are seen, the murmur will no longer be heard.  In these circumstances: case closed.  If the murmur persists, they can be referred then (either for an echo or to paediatrics if they don’t have direct access to this), assuming that the child remains red-flag-free.

Case 2

A two month old baby presents with a runny nose, cough and a low grade temperature.  The parent has noticed that their baby has started to have slightly fast breathing and has not been feeding as well as they normally do.  On examination, the baby has a slight wheeze, mild recession and basically looks like the other babies with bronchiolitis that you have seen that month.  All except for one thing: they have a soft systolic murmur that you can just about hear over the wheeze.

What now?

In short, refer to the acute paediatric medical team.  This child might have bronchiolitis and a flow murmur, but there is every chance that they are just pretending to have bronchiolitis.  Babies who have a ventricular septal defect (VSD) might not be picked up on screening (newborn baby checks etc.) and may have no overt symptoms, until they get their first cold.  Then, shortly after becoming snotty, the illness tips them into heart failure.  What does heart failure look like in a baby?  Well, they have increased work of breathing, a bit of a wheeze and struggle to feed.  Does that sound like bronchiolitis or does that sound like bronchiolitis?

Other clues that give these mimics away are:

  • Excessive tachycardia
  • Hepatomegaly
  • More pale or mottled
  • The course of the illness is different – they continue to get worse, while bronchiolitis symptoms peak at day 3-4 of the illness.

Case 3

A fourteen year old presents a few days into a flu-like illness.  They have been seen by a couple of doctors in the past few days, and have been told that they have a viral illness.  On both occasions they were advised about symptomatic treatment.  The parents are concerned that the young person is not getting better.  On examination, there is a barely audible systolic murmur.

What now?

Don’t presume this to be a flow murmur.  Firstly, in the context of viral illness, flow murmurs are most commonly heard in younger children. Also, the the murmur was not heard on previous visits.   One possible diagnosis here is viral myocarditis.  Other possibilities include bacterial endocarditis.

What next?

Refer this child acutely to the paediatric medical team.


One general rule which works quite well for symptoms in children (in the context of heart problems) is this: An isolated sign or symptom is rarely indicative of significant pathology.  Two signs or symptoms is always worth taking very seriously.  Take chest pain in children.  I don’t expect chest pain to be due to a cardiac cause in children (because it almost never is).  I know that the vast majority of children who have a syncopal episode will be having straightforward vasovagal events.  However, chest pain in combination with syncope, dyspnoea or palpitations is presumed by me to be pathological until said pathology is excluded.


So, as with many presentations in children, everything is normal except when it isn’t.

Edward Snelson
Postcordiologist
@sailordoctor



Many thanks to Dr. Carrie Mackenzie (Consultant paediatrician) who helped with the original version of this piece which is on the excellent RCEM learning site.


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