Forget timing, pitch, intensity and clicks, because ruling out cardiac disease among children could come down to whether the murmur disappears when they stand up.
Unnecessary referral to paediatric cardiologists is anxiety-producing and costly, for both the families and the healthcare system, but many paediatricians and family doctors worry about missing a significant cardiac disease. So in order to determine whether simple, robust and objective clinical test to exclude cardiac disease in otherwise healthy children, French researchers scanned the hearts of almost 200 children aged two or older with a heart murmur referred to paediatric cardiologists.
Only one in six of these children had murmurs that were pathological as determined by an echocardiogram. And researchers found that murmurs that became inaudible when the child stood up correlated well with non-pathological cases.
The researchers used a nonelectric stethoscope to listen to the hearts of children as they lay supine and then when they stood up.
Among the 100 children whose murmur disappeared when standing up, only two were found to have underlying cardiac pathology, the authors found. This gave the clinical sign a 93% specificity and a positive predictive value of 98%.
“In this era of highly technical medicine, physical examination should remain the first step of diagnosis,” they wrote.
Heart murmur affects 65% to 80% of schoolchildren and is one of the most common reasons children are referred to cardiologists, the authors wrote.
But the small proportion of children who actually had an abnormal echocardiogram indicated over-referring was occurring, they said.
“In our study, 85% of children aged two to 18 years referred to a cardiologist for heart murmur did not have a cardiac disease, showing the lack of a basic and reliable clinical measure to reassure primary care physicians of the absence of cardiac disease in paediatric patients with heart murmur,” they wrote.
“Even if sensitivity of this test is low, it would have decreased the number of referrals to paediatric cardiologists for murmur by more than one half, reducing the workload of a paediatric cardiology unit having limited professional resources,” they explained.
Paediatric cardiologist Associate Professor Gary Sholler, director of cardiac services at the Sydney Children’s Hospitals Network, said the disappearance of heart murmur had long been a good tool in assessing the need for further referral.
But he said the sensitivity and specificity found in the study meant that listening to the heart while the child changed positions was “quite useful to find something that might be present, it’s not that useful to completely rule out an abnormality”.
“Now that’s the problem that GPs and paediatricians have. What is the tolerance for not knowing?”
He said that reassuring an anxious parent by referring to a specialist was, in certain contexts, a valuable part of the therapeutic relationship.
Healthy children could have a heart murmur simply from normal blood flow through the heart and great vessels, they said, but it disappeared upon standing because the venous return shrank, alongside the left ventricular chamber and stroke volume.
The study population did not include children with a family history of heart disease, or who had genetic or systemic disorders, because any of these was enough to warrant a referral to a specialist, the authors wrote.
Professor Sholler echoed that point, saying while listening for the disappearance of a murmur upon standing was a valuable tool to add to the clinical examination, sometimes the threshold for referral might be lower when considering young age, murmur that was persistent or creating uncertainty or other health issues with the child.
“All of those may be completely legitimate reasons for the child to be evaluated.”