A recent study assessed the value of cardiac signs and symptoms in predicting a pathologic heart murmur and concluded that these symptoms are significantly helpful as a diagnostic aid, but the predictive values are variable depending upon the age of the pediatric patient and corresponding ability or inability to assess certain signs and symptoms.12 Aside from the direct cardiac exam, other physical exam components that should be evaluated in an infant or child with a cardiac murmur include vital signs (such as temperature [fever], pulse rate, respiratory rate, and BP), oxygen saturation, peripheral pulses, respiratory effort, cyanosis or pallor, carotid arteries for bruits, and jugular veins for abnormal pulsations.7 When assessing peripheral pulses, the brachial and femoral pulses are typically used for neonates and infants, whereas the radial and femoral pulses are used in children and young adults.13
Differentiating common pediatric heart murmurs
In the pediatric population, there are four common innocent heart murmurs: Still murmur, pulmonary flow murmur, systolic flow murmur, and the venous hum. These murmurs are also known as functional murmurs, but the term "innocent" is preferable to use when educating families because it communicates more clearly to the parents that there is nothing abnormal or problematic about the murmur.7 Innocent murmurs are more straightforwardly distinguished because they share the following characteristics: they occur in early systole (except venous hum), have a short duration, are typically grades 1 or 2 on the Levine grading scale, and have a vibratory or musical quality.6 Because innocent murmurs are caused by normal blood flow, it is expected that the murmurs should change in sound or intensity with positional changes that alter the normal blood flow. Several position changes and maneuvers can be performed to alter normal blood flow in order to help discern innocent from pathologic murmurs and provide clues to the specific murmur etiology. (See Interventions for altering the intensity of heart murmurs).
Still murmur was named for the surname of a physician who described a pediatric murmur with a musical quality in the year 1909.14 He followed his pediatric patients who presented with this murmur and after some time concluded that the murmur was not producing any abnormal signs and symptoms and was, therefore, innocent in nature.13 Still murmur can be heard in early systole best between the apex and the left lower sternal border.15 This murmur has a vibratory quality that can be compared to the twanging of a stringed instrument or rubber band; it has been likened to the sound of a harp string being plucked or a buzzing sound.14
The pulmonary flow murmur is heard during systole and is most easily audible at the left upper sternal border.15 It typically has a high pitch with a harsh quality and originates from the right ventricle outflow carried through the pulmonary arteries. For this reason, it may radiate bilaterally to the back and axilla.7 Pulmonary flow murmurs are more common in children and adolescents and less common in neonates and infants. When the cardiovascular system develops, only 10% of blood flows to the far branches of the pulmonary arteries, but later in life when the cardiovascular system becomes fully developed, the pulmonary arteries become larger and have greater blood flow.7
The systolic flow murmur is high-pitched, harsh sounding, and best heard in the superior chest and vessels of the head and neck.7 Its characteristic sound caused by normal blood flow through the carotid arteries helps differentiate the systolic flow murmur from a carotid bruit, which is caused by abnormal aortic outflow. Both pulmonary and systemic flow murmurs originate from a physiologic increase in blood flow, and can be classified as hemic murmurs when blood flow naturally increases to compensate for such conditions as anemia or fever.7
The venous hum is a musical murmur that like Still murmur has a vibratory quality.15 It is best heard at both the upper right and left sternal borders and inferior neck region, and it is caused by blood flow returning to the heart through the venous system.7 The venous hum is the only innocent murmur heard during diastole.6 A few isolated case reports indicate that a venous hum may be audible to the child and may cause tinnitus, but this is not typical in the majority.16
A recent study identified several physical exam findings that were independently associated with the presence of a congenital heart defect in neonates: harsh quality, location in either the aortic location (right upper sternal border), tricuspid location (left lower sternal border), or mitral location (apex), pansystolic timing, diastolic timing, and continuous murmurs.17 As a general rule, pathologic systolic murmurs are longer in duration and greater in intensity than innocent murmurs.6 If the murmur is heard during diastole (with the exception of the venous hum) or is holosystolic, the murmur is pathologic.6
A patent ductus arteriosus produces a continuous, holosystolic murmur best heard at the upper left sternal border and left inferior neck region. In normal growth and development, the ductus arteriosus closes by the fourth day of life, so this murmur is often found in premature newborns. The murmur of a patent ductus arteriosus is also associated with full and prominent pulses in children.2
An atrial septal defect causes a murmur best heard during systole that is loudest at the upper left sternal border. It is characterized by wide, fixed splitting of S2, and occasionally an additional murmur is heard during diastole resulting from increased blood flow across the tricuspid valve.2 A ventricular septal defect produces a systolic murmur that may last the entire duration of systole. This murmur is characterized as a blowing sound with a harsh quality, and there is frequently a palpable thrill.2
The murmurs of both aortic and pulmonary stenosis are associated with ejection clicks.2 When auscultating the murmurs, a click will be heard as a sharp sound with a moderately loud intensity following S1.6 Another pathologic murmur can be caused by coarctation of the aorta. This murmur is systolic and heard best at the upper left sternal border and left posterior scapular area. It usually has a low volume but may be very intense and is associated with weakened femoral pulses and increased BP.2
The murmur of mitral regurgitation occurs from a disruption in the normal functioning of the mitral valve in which the valve leaflets are pushed back into the left atrium during left ventricular systole. Likewise, the murmur of aortic regurgitation occurs from a disruption in the normal functioning of the aortic valve in which the valve leaflets are pushed back into the left ventricle during left ventricular diastole. The murmur of mitral regurgitation is typically holosystolic while the murmur of aortic regurgitation is only heard throughout diastole.18
Mitral stenosis and aortic stenosis are caused by the calcification or fibrosis of the mitral and aortic valves respectively. Aortic stenosis usually presents as a mid-systolic or systolic ejection murmur, while mitral stenosis is usually a very quiet rumble heard during diastole (see Features of pediatric heart murmurs).18
Diagnostic testing and indications for referral
The ECG and the chest X-ray have limited use in the diagnosis of underlying pathology associated with pathologic heart murmurs, with low sensitivity and specificity for identifying cardiac defects or anatomical abnormalities.13 A chest X-ray is not recommended in pediatric clients because it unnecessarily exposes the infant or child to ionizing radiation. The ECG has little benefit for diagnosis of congenital heart defects because the majority of heart murmurs are found in asymptomatic patients.2 Nonetheless, the ECG should be considered as part of the routine physical exam for pediatric patients with a heart murmur because it is noninvasive, easily conducted in the outpatient setting, useful to determine the need for further diagnostic testing through echocardiography, and has a high predictive value in ruling out cardiac dysrhythmias.13
The echocardiogram is the gold standard to definitively diagnose congenital cardiac malformations in pediatric patients.13 According to the American College of Cardiology/American Heart Association Task Force on Practice Guidelines, if a murmur is present and an abnormal chest X-ray or abnormal ECG is obtained, an echocardiography is indicated9 (see Evaluation of heart murmurs in the pediatric population). For pediatric patients with moderate left-sided congenital heart defects, it is recommended that a repeat echocardiography be done if there is a change in cardiac status or every 2 to 5 years, whichever occurs first.18 For patients with left-sided congenital heart defects that are severe, it is recommended to repeat echocardiography at least yearly.18
If there is any confusion about discerning an innocent from a pathologic murmur, or if additional reassurance regarding a suspected innocent murmur is desired by the parent, referral to a pediatric cardiologist is a prudent and recommended action on the part of the NP.7 Referral for specialty management of pediatric heart murmurs is indicated in the presence of symptomatic left-sided cardiac murmurs, aortic murmurs with concomitant chest pain or syncope, and echocardiography yielding overload of the right ventricle with a murmur caused by mitral valve disease.18 Further research is needed to establish a general recommendation regarding specialty referral of neonatal patients with asymptomatic heart murmurs.19
If a patient has a murmur associated with mitral regurgitation and demonstrates heart failure symptoms, left ventricular dysfunction, atrial fibrillation, or pulmonary hypertension, referral to a cardiology specialist for surgery is indicated. Referral is also indicated in the presence of suspected severe aortic regurgitation. With any severe left-sided valve lesions found on echocardiography, or major left ventricular dilation, hypertrophy, or other dysfunction, referral to a cardiologist is indicated; if similar conditions are right-sided, cardiology referral is appropriate to consider.18
Patient and family education
The NP is often the first person to find a heart murmur in a pediatric patient, and therefore is in a unique position to provide education regarding heart murmurs. Reassurance for the patient and the family regarding the benign nature of innocent murmurs is important. Although the murmur may never disappear and can persist into adulthood, the parents and child can be specifically educated that innocent murmurs are additional sounds heard as a result of normal blood flow patterns, and therefore are completely harmlessness. Because these murmurs can be altered with positional changes and normal growth and development, parents should be educated that innocent murmurs may seem to disappear and reappear throughout the course of the child's life. The misconception that heart murmurs in adults are always pathologic can also be clarified. Finally, the NP can allay fears about the likelihood of a murmur originating from a congenital heart defect with the statistic that less than 1% of pediatric murmurs actually have this etiology.7
Heart murmurs are a frequent finding in the pediatric population. The majority are innocent in nature, and the ability to correctly distinguish these physiologic from pathologic murmurs is a critical responsibility of the NP. Fortunately, the differential diagnosis of most common pediatric heart murmurs may be accomplished based solely on knowledge of clinical presentation and associated features of each murmur. When a murmur presents in accordance with pathologic signs and symptoms, diagnostic testing by means of echocardiography is often indicated. Pathologic murmurs are almost always indications for referral and management by a pediatric cardiologist. The primary care NP is in a unique position to identify new onset cardiac murmurs and educate the patient and family regarding the specific cardiac findings and implications on the health of the patient.
Evaluation of heart murmurs in the pediatric population9
– Asymptomatic and no associated signs or symptoms → No further workup
– Symptomatic or other signs of cardiac disease → Echocardiogram
- Grade 3 or more → Echocardiogram
Early systolic, late systolic, holosystolic → Echocardiogram
Diastolic and Continuous Murmurs
– Cardiac catheterization and angiogram may be indicated
Exceptions: Continuous venous hum → No further workup
*Murmurs are graded using the Levine grading scale.
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Keywords:© 2011 Lippincott Williams & Wilkins, Inc.
innocent murmur; pathologic murmur; pediatric heart murmurs