All heart murmurs need to be treated

Which ones need to be clarified in more detail?

Up to 50% of children and adolescents with a healthy heart develop heart murmurs during growth that are not based on any cardiac pathology. At the same time, heart murmurs are the most common indication for an examination by a pediatric cardiologist. The present work contains guidelines that enable the physician to weigh up an assignment to the pediatric cardiologist and to reinforce his position if a wait-and-see approach can be adopted towards the parents and the children in care.

Heart murmurs are caused by turbulent flow in the blood vessels with frequencies of 20 to 2,000 Hz [1]. A precise characterization of the sounds is a great challenge for babies, who often have a higher heart rate. For primary care providers and specialists, despite echocardiography, a careful examination is the basis for good patient selection.

Which heart murmur should be clarified?

It has been proven that the primary care physician can distinguish very well between pathological and non-pathological heart murmurs. The referral practice is often guided by aspects other than actual clinical characteristics [2]. More important than the exact description of the noise character in words seems to us to pay special attention to the age of the child in the assignment practice. In addition to the description of the localization of a heart murmur, the focus on the heart tones, in particular on the second heart sound, is important.

Palpation and auscultation

The palpation is supposed to detect buzzing, which characterizes organic noises and gives differential diagnostic clues through its localization. A heart murmur that is accompanied by a buzz should always be clarified by the pediatric cardiologist. The first heart sound comes off at the same time as the AV valves close. It is usually singular. The second heart sound occurs when the semilunar valves close, with the aortic valve closing just before the pulmonary valve. Normally, the second heart sound is maximally split during inspiration, when the right heart has to cope with a higher cardiac output. During expiration, the second heart sound is not or less audibly split. One speaks of a second heart sound split in a physiologically variable manner in terms of breathing. If there is an atrial septal defect, the breathing-dependent variability of the split of the second heart sound is balanced out by the left-right shunt, and the second heart sound is fixed. Another important parameter is the intensity of the second heart sound. A loud, throbbing second heart sound is typical of pulmonary hypertension.

Heart murmurs should be characterized as follows:

  • Energy (volume) of the sound wave (see table)
  • Frequency (low, medium, high)
  • Relation to heart sounds (systolic, diastolic) and duration in relation to heart sounds (e.g. holosystolic, crescendo / decrescendo)
  • Presence of harmonic overtones (musical noises)
  • Localization with punctum maximum, which usually leads to a suspected diagnosis
  • Other adjectives such as “breathing and pouring” are hardly helpful and distract more from the system.

An isolated diastolic is pathological and must be clarified.

The accidental heart murmur

If a pediatric cardiological investigation is not carried out in the case of a heart murmur, all the characteristics that indicate that it is actually an accidental heart murmur must be met. The noise must be the only "noticeable" finding. There should be neither a syndromic disease (such as trisomy 21) nor a failure to thrive or even symptoms that cannot be explained otherwise, such as drinking weakness and / or exercise intolerance. The most common, "Stillsche", heart murmur typically occurs between the ages of two and six years. It is medium-frequency and position-dependent; it is loudest when lying down. The musical component, the swing, is typical of this noise. Its exact genesis is unclear. There must be neither palpable buzzing nor abnormal localization or radiation. These noises only need to be clarified in the event of uncertainty or additional findings.

The second, rarer, juvenile pulmonary systolic has a frequency peak between the 10th and 14th year of life or in adolescents. It is a less musical systolic sound of strength 1/6 to 3/6 that can be auscultated parasternally over the second intercostal space on the left.

Venous flow sounds are less commonly diagnosed. They usually occur in children between the ages of 3 and 6. Venous flow sounds ("venous hum" or "Nonnensausen") can be heard in the second intercostal space on the right or left as continuous, i.e. systolo-diastolic flow sounds, especially when sitting and during inspiration with turning the head to the opposite side. These noises are between 1/6 and 3/6 loud.


Newborns with a persistent heart murmur at the age of 48 hours should be presented to a pediatric cardiologist as soon as possible in the following days, even without symptoms. Additional symptoms such as cyanosis, lack of femoral pulse or other abnormalities as well as an "uneasy feeling" on the part of the doctor require immediate contact with a pediatric cardiologist earlier. In particular, weakened lower extremity pulses or cyanosis are an emergency situation in the newborn. Pulse oximetry screening is also helpful in diagnosing congenital heart disease in this situation [3]. Signs of heart failure (sweating, tachypnea, failure to thrive) typically occur between 2 and 6 weeks of age when there is shunt disease. Edema is not a typical sign of heart failure in infants.

Because of the relatively high incidence of congenital vitii discovered in newborns, a general referral of the newborn with a systolic to a specialist after the adaptation phase can be justified even if there are no symptoms. Peripheral pulmonary stenosis and, more rarely, the persistent ductus arteriosus Botalli are the most common diagnoses that theoretically would justify waiting. Peripheral pulmonary stenosis is caused by the circulatory change in the lungs, which were only slightly perfused before birth, and is characterized by normal heart tones and a medium-frequency noise radiating into the back and axillae above the second intercostal space. The systolo-diastolic machine noise of the open ductus arteriosus is relatively easy to recognize. A small atrial septal defect cannot be clinically differentiated from an open foramen ovale in the first months of life and has no therapeutic consequences at this age, since the right-sided heart cavities are hardly stressed with a small defect.

In the first year of life

In the first half of life, due to the good availability of echocardiography in Central Europe, practically all structural congenital heart defects are usually recorded, as the children become symptomatic due to failure to thrive, cyanosis or signs of heart failure or the auscultation findings are very conspicuous. If there is a systolic that is suspicious for the primary care provider, this is the moment to refer the children, as the examination, especially the echocardiography, can usually be carried out completely without problems up to an age of approx .

In the second and third year of life

In the second half of life, especially after the age of nine months up to the end of the third year of life, the experienced pediatric cardiologist can exclude a hemodynamically relevant vitium from the combination of clinical examination and echocardiography, even in less cooperative children, but these examinations are very time-consuming - and thus costly, since there are no calm examination conditions. It is important for the referring physician to know that a full examination is then often only possible in sedation.

Structural heart defects are rarely diagnosed in Central Europe in the 2nd and 3rd year of life. At this age, coarctation of the aorta and atrial septal defects are in the foreground, with coarctation of the aorta being diagnosed in the first six months of life. Mild tachypnea and tachycardia are not obligatory. After the ductus arteriosus has been closed, newborns with coarctation of the aorta often show signs of decompensation and weakened or absent femoral pulses. Later, depending on the severity of the coarctation of the aorta, arterial hypertension of the upper extremity, weakened femoral impulses and a left paravertebral stenosis sound dominate. Coarctation of the aorta is rarely diagnosed until school age.

A haemodynamically significant atrial septal defect shows a flow noise, sometimes similar to the functional heart murmur, in the area of ​​the pulmonary artery (second parasternal left intercostal space). The second heart sound is fixed in the presence of an atrial septal defect. Treatment (surgical closure) is only necessary if there is a simultaneous failure to thrive, recurrent pulmonary infections or, in rare cases, increased pulmonary pressure (throbbing second heart sound!). Otherwise, they will wait until pre-school age and, if possible, try to achieve a catheter-internal closure. In the 2nd and 3rd year of life, heart murmurs are seldom a reason for referral, but anamnesis, pulses of the lower extremity and the precise assessment of the second heart sound are also in the foreground for the sub-specialist. If the children in this age group become symptomatic, a serious illness such as cardiomyopathy is usually present.

School children

Beyond infancy, congenital heart diseases that manifest themselves are very rarely discovered, apart from the aforementioned atrial septal defect and coarctation of the aorta. The focus is on acquired myocarditis as well as cardiac arrhythmias and cardiomyopathies. Dilated cardiomyopathy can manifest itself, for example, through mitral valve insufficiency, accompanied by a holosystolic over the apex of the heart, radiating into the axilla. If the physiology is restrictive, a third heart sound (filling sound) and a fourth heart sound (atrial contraction) can sometimes be heard as a gallop rhythm.

Hypertrophic cardiomyopathy is an important differential diagnosis. This heart murmur becomes louder when standing than when lying down. In the upright position, the venous blood flow back to the heart is lower than in the lying position. This reduces the left ventricular end-diastolic volume. If this reduces the left ventricular size and narrows the left ventricular outflow tract, the systolic outflow tract narrowing in hypertrophic cardiomyopathy also increases. This increase in the narrowing of the outflow tract amplifies the noise when the patient is in an upright position. Overall, hypertrophic cardiomyopathy is a rare disease. However, it is one of the leading causes of sudden cardiac death in active athletes [4].

Guidelines: wait or assign?

For every child with a heart murmur, a detailed anamnesis should first be taken, which in particular records risk factors for the presence of cardiac pathology. In combination with a good clinical examination, the typical character of the noise can often make a diagnosis of an accidental noise. A further diagnosis by a pediatric cardiologist is necessary for newborns if the heart murmur cannot be classified as accidental or if the parents are uncertain or worried. In any case, however, an allocation should be made if the noise reaches grade ≥ 3/6, in the case of noises that are accompanied by a palpable buzz, diastolic heart sounds and pathological heart sounds. Furthermore, in the case of other cardiac symptoms, changes in the pulse quality of the lower extremities, pathological ECG or chest x-ray as well as the presence of extracardiac malformations, which can often be associated with a heart defect.

A patient who has a pathological finding on a clinical cardiac exam, has cardiac symptoms, or a questionable unclear finding on a cardiac exam should be referred to a pediatric cardiologist. A child with a malformation often associated with congenital heart defects should also be referred for a pediatric cardiological assessment and evaluation [5]. In contrast to this, asymptomatic patients, in whom, after a carefully conducted clinical-cardiological examination, a low probability of the presence of cardiac pathology can be assumed, can be checked and followed up by the general practitioner or pediatrician. Referral is indicated when possible pathological findings are to be made during serial examinations.

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2. McCrindle BW, Shaffer KM, Kan JS, Zahka KG, Rowe SA, Kidd L. Cardinal clinical signs in the differentiation of heart murmurs in children. Arch Pediatr Adolesc Med 1996; 150 (2): 169-174.
3. Arlettaz R, Bauschatz AS, Mönckhoff M, Essers B, Bauersfeld U: The contribution of pulse oximetry to the early detection of congenital heart disease in newborns. Eur J Pediatr 2006; 165 (2): 94-98.
4. Maron BJ, Epstein SE, Roberts WC. Causes of sudden death in competitive athletes. J Am Coll Cardiol 1986; 7: 204-214.
5. McConnell ME et al .: Heart Murmurs in Pediatric Patients: When Do You Refer? Am Fam Physician 1999; 60: 558-565.
6. Gibson S. The clinical significance of heart murmurs in children. Med Clin North on 1946; 30: 35-44.
7. Friedman S, Robie WA, Harris TN. Occurrence of innocent adventitious cardiac sounds in childhood. Pediatrics 1949; 4 (6): 782-789.

Edited and approved reprint from Ars medici Pädiatrie 3/2011

Senior physician in charge of cardiological polyclinic
University Children's Hospital Zurich