When an NP performs a cardiac assessment on a pediatric patient, the parents are often relieved when the findings are normal. If an atypical heart sound is identified, the ability of the NP to correctly discern the etiology as either physiologic or pathophysiologic is vital to both the care of the patient and the consolation of the family. Many cardiac murmurs are innocent with no harmful effects on the health of the child; the NP can provide reassurance to the family when an innocent murmur is found based on results of a confident and accurate assessment. Other cardiac murmurs are indicative of serious and potentially life-threatening problems; these may need referral to a specialist or immediate emergency treatment. Knowledge regarding clinical presentation of common pediatric heart murmurs, the impact of these murmurs on the health of the child, and the recommendations for diagnostic testing and referral are critical for evaluation and management in primary care.
Overview of pediatric heart murmurs
According to the National Heart Lung and Blood Institute, a heart murmur is defined as "an extra or unusual sound heard during a heartbeat."1 In the pediatric population, innocent heart murmurs (those considered to be a variation of normal, not attributable to a problematic health condition) account for the majority of cases. Innocent murmurs are most often caused by turbulent blood flow through the pulmonary arteries or a slightly patent ductus arteriosus from delayed cardiac development in the neonate or prematurity.2,3 Conversely, pathologic heart murmurs are most commonly associated with a ventricular septal defect or a more severe patent ductus arteriosus, and may also result from congenital heart disease (see Ventricular septal defect and patent ductus arteriosus).2
In the newborn population, the prevalence of heart murmurs is between 0.6% and 4.2%.4 Among infants and children, an estimated 90% will have a heart murmur at some point during their infancy or childhood.5 Approximately 50% to 70% of infants and children are reported to have a heart murmur identified during a routine physical exam,6 but of all pediatric heart murmurs, less than 1% are caused by a congenital heart defect.7 About 70% of heart murmurs are asymptomatic in infants and children, and asymptomatic murmurs may be either innocent or pathologic.2
Assessing pediatric heart murmurs
When auscultation of the heart yields normal findings, the first heart sound (S1) is heard as the atrioventricular valves (mitral and tricuspid) close and ventricular systole begins, and the second heart sound (S2) is heard as the semilunar valves(aortic and pulmonic) close and ventricular diastole begins; no other heart sounds are heard and the heart rhythm is in a regular pattern.8 When a murmur exists, an atypical heart sound is heard that may occur at various times throughout the course of the cardiac cycle depending upon the type and cause of the murmur. There are three main factors responsible for the production of a heart murmur: (1) turbulent blood flow through vasculature or a normal or abnormal opening in the heart; (2) blood flow traveling forward through a narrowed valve into a dilated heart chamber or vessel; or (3) blood flow traveling backward or regurgitating into a previous heart chamber through an incompetent valve.9
The cardiac exam
The three components of the cardiac exam are observation, palpation, and auscultation, and the order of these components is flexible in the pediatric population.6 Auscultating the heart of a pediatric patient before palpating the precordium is often recommended because the patient may be calmer early in the exam, making the heart easier to hear. When auscultating the heart, it is advised to first listen for the normal heart sounds of S1 and S2 before trying to detect the presence or absence of a murmur.8 This allows the NP to identify cardiac dysrhythmias and determine the presence or absence of the third and fourth heart sounds (S3 and S4). Murmurs are typically described as having a harsh quality, a blowing sound, or a musical characteristic. The diaphragm of the stethoscope is most useful for hearing sounds with higher pitch, whereas the bell is best for sounds with lower pitch.8
Direct observation of the precordium is useful because it can identify a heartbeat visibly moving the chest or abdomen.5 Although some of the information obtained through observation does not directly assess the heart, such as breathing patterns and distension of the jugular veins in the neck, abnormalities can still indicate cardiac problems. Thrills can be identified by palpation of the precordium, and the arterial pulses can be compared bilaterally by palpation to identify heart conditions such as coarctation of the aorta.5
Classification and grading of murmurs
Heart murmurs are generally classified according to timing (timing during the cardiac cycle), intensity (a grading scale that describes the intensity or volume of the murmur), quality (harsh, rumbling, vibratory, blowing, or musical), pitch (low, medium, or high), location (the anatomic location wherein the murmur is heard best), and radiation (the site farthest from the location where the murmur can still be heard).
The timing of a murmur in the cardiac cycle is identified as systolic, diastolic, or continuous. There are four types of systolic murmurs (holosystolic, mid-systolic, early systolic, and mid-to-late systolic) and three types of diastolic murmurs (early diastolic, mid-diastolic, and late diastolic). A holosystolic or pansystolic murmur is heard throughout the duration of systole, whereas a mid-systolic also known as a systolic ejection murmur begins after S1. Systolic ejection murmurs are characterized by a brief crescendo in volume followed by a decrescendo just before systole ends. An early systolic murmur begins simultaneously with or immediately after S1 and ends midway through systole, while a mid-to-late systolic murmur begins midway through systole and ends just before diastole.9 An early diastolic murmur is high-pitched and begins simultaneously with or immediately after S2. A mid-diastolic murmur is heard shortly after S2 and ends before the next cardiac cycle, while a late diastolic murmur (also known as a presystolic murmur) occurs just before ventricular contraction when the atria have contracted and the ventricles are filling. Continuous murmurs are constantly heard behind the heart sounds.9
The intensity or volume of the murmur is assessed and documented by a system of grading, in which higher grades indicate a louder murmur. The most common grading system was developed by Levine in 1933, in which both systolic and diastolic murmurs are given a grade from 1 to 6.10 A grade 1 indicates that the murmur is barely audible through the stethoscope, whereas a grade 6 indicates that the murmur is audible with the stethoscope lifted off the chest. Diastolic murmurs rarely reach grades of 5 to 6. In addition to the Levine grading scale, there is another common grading scale for murmurs used that was developed by Wood and Leatham, two British cardiologists.11 Their grading scale is similar in that louder murmurs receive higher grades, but Wood and Leatham use a smaller scale of grades 1 to 4, making the two grading systems incompatible because the range between grades is not identical for the two scales. Therefore, it is useful to document the grading system used concurrently with the grade assigned to a murmur (see The Levine grading scale for heart murmurs).11
History and further physical exam
The NP can ask the patient and/or family about symptoms possibly indicating congenital or acquired heart disease such as chest pain, palpitations, syncope, activity intolerance, changes in skin color, or growth and development delays. For neonates and infants, the pertinent history includes information about length of gestation, birth history, normal habits of feeding, difficulty breathing when feeding, and usual level of activity.6 For all pediatric patients with a heart murmur, it is especially important to obtain a thorough family history of congenital cardiac conditions (such as congenital heart defects and heart disease) because they are more likely to occur in patients with a first-degree relative with a history of a congenital heart condition.7
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).
Table. Interventions...Image Tools
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
Table. Features of p...Image Tools
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
* Grade 2 or less
– 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.
© 2011 Lippincott Williams & Wilkins, Inc.