Summary

It is incredibly common to have a heart murmur as a child. As much as 30% to 75% of children prior to the age of 18 years have been noted to have a heart murmur. Congenital heart disease occurs in 6 to 8 out of 1000 cases with a murmur. Crunching these numbers, a primary care physician may hear as many as 100 murmurs prior to detecting 1 patient with congenital heart disease. Since the large majority of heart murmurs do not represent underlying pathology, the primary care physician needs to know well the innocent murmurs, in order to distinguish them from the pathologic. This not only takes years of experience, but also utilization of a careful systematic approach to an initial evaluation of heart murmurs.

Educational objectives

At the conclusion of this activity, participants will be able to:

• Conduct a systematic initial evaluation of a heart murmur
• Recognize common innocent murmurs of childhood
• Determine when referral to pediatric cardiology is necessary

CME credit

This is an article from The Child's Doctor, Spring 2006 issue. You may take the quiz for learning purposes, but credits are no longer valid.

Author disclosures

Dr. Pophal has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

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A murmur is the most common and sensitive finding on physical exam that leads to the diagnosis of congenital heart disease, and it is the leading reason for pediatric cardiology evaluation. Echocardiography, cardiac catheterization, 64-slice computerized tomography (CT) and magnetic resonance imaging (MRI) technology have enhanced the precision and improved the accuracy of diagnosing congenital heart disease. Heart lesions are, however, first suspected on a careful physical examination. It should be anticipated that parents would become anxious about a potential heart problem in their child. Heart disease is the leading cause of death in the United States. Naturally, any parent may have been sensitized to a relative or friend with a heart problem. In the pediatric cardiology clinic, parents are told that a murmur "is just a noise. It can be a good noise or a bad noise." It is the goal of the primary care physician to alleviate parental concerns, but at the same time not to miss a significant heart lesion.

Auscultatory approach to a heart murmur

Every doctor, advanced practice nurse, or medical assistant has his or her own approach to listening to the chest. Achieving patient comfort and obtaining a thorough examination are more of an art than a skill. The room certainly must be quiet and the patient at ease to truly appreciate some specifics of heart murmurs. The murmur must accurately be described in terms of its loudness, site of maximal intensity and timing. Murmurs are graded from 1 to 6 (see Table 1).

Practically speaking, murmurs are considered either loud or soft because despite the accurate gradation of murmurs there is still controversy. The site of maximal intensity at first listen could be misjudged, but with careful reevaluation can be accurately described to help decipher innocent versus pathologic murmurs.[1] Most murmurs are heard along the sternal border. Upper sternal borders can be on the right side or on the left. Lower sternal borders are typically on the left side with variable gradation. Systematic auscultation of all areas of the chest and reassessment are imperative to finding the maximal intensity of murmurs. The timing of a murmur is also important. All diastolic murmurs are pathologic. However, most murmurs are systolic and can accompany a short period of systole or an entire period of systole. Continuous murmurs despite their name are not heard throughout the entire cardiac cycle. Continuous murmurs start in systole and continue without a pause into diastole.

In addition to the loudness, site of maximal intensity and timing, multiple adjectives can be used to describe some of the classic tones and qualities of heart murmurs. A twangy, musical vibratory murmur that is soft and at the left lower sternal border can almost universally be diagnosed as an innocent Still’s murmur. A harsh machinery continuous murmur at the high left sternal border, subclavicular area is not innocent and consistent with a PDA (patent ductus arteriosus). Most harsh holosystolic murmurs at the lower left sternal border are VSDs (ventricular septal defect). Pediatricians should not be afraid to use multiple adjectives to describe murmurs, as these can be useful for follow-up referrals and cross coverage.

Common innocent murmurs

To distinguish murmurs that are not typically innocent, a pediatrician needs an understanding of the most common innocent murmurs of childhood. These can be divided into 4 groups reviewed below.

Vibratory or Still’s murmurs are typically heard after infancy and are very common. The most striking finding is the well localized nature and musical quality to these murmurs. These are best heard at the left lower sternal border with either radiation to the apex or to the upper sternal borders. They are variable with changes in position, and can be more pronounced after simple exercise. A compliant patient can do multiple jumps or jumping jacks in the examination room and then be reevaluated. If the murmur is musical and vibratory, this is likely to be innocent. Occasionally, mitral valve prolapse with mitral insufficiency can have a similar finding, as can a small apical muscular VSD. Muscular VSDs are more pronounced and mitral valve prolapse with mitral insufficiency has a more "honking" quality than the musical buzzing quality of a vibratory Still’s murmur.

Pulmonary flow murmurs are more common in infancy, but can be heard at any age. Physiologic pulmonary branch stenosis is a term used for premature infants who have underdeveloped pulmonary vascularity. Due to the acute branch patterns and small nature of the distal pulmonary artery branches, turbulence is created. The murmurs of physiologic peripheral pulmonary stenosis are loudest in the periphery. A grade 2 murmur at the left upper sternal border that is also a grade 2 in the axilla and back is most consistent with peripheral pulmonary stenosis. This is physiologic in the absence of systemic disease or syndromes such as William’s, Allagille’s, Noonan’s, and Turner’s syndrome or congenital rubella. Typically these flow murmurs resolve at 1 to 2 years of life, but should gradually become softer during this time period.

Less intense pulmonic and aortic flow murmurs can occur later in childhood and are usually graded 1 to 2. They are not accompanied by clicks, which suggest congenital abnormalities of the semilunar valves. Conditions that increase cardiac output, such as anemia, infection, fevers and dehydration, can intensify these murmurs making them more pronounced.

Venous hums are common in toddlers and pre-adolescents. They generally are rumbling distant sounds under the clavicular areas and are heard well when the patient is standing and facing forward. With changes in position these murmurs disappear. Turning the patient’s head or lying the child down should cause a decrease in intensity or disappearance of these murmurs.

Functional murmurs are heard at the left sternal border with radiation to the right upper sternal border. These are quite common (10%-20% of all innocent murmurs), but is difficult to easily conclude that they are functional. Typically murmurs in this area are short and graded 1 or 2 in intensity. A murmur any louder than grade 2, especially in infancy, should alarm the primary care physician of pulmonary or aortic stenosis, necessitating immediate referral to a pediatric cardiologist. Significant pulmonary or aortic stenosis is accompanied by a click. However this is difficult to identify in a patient with a rapid heartbeat. Hypertrophic cardiomyopathy can also present with a systolic ejection murmur in this area. These murmurs decrease in intensity in the squatting position and increase upon standing, as systemic vascular resistance and systemic venous return are decreased. Any adolescent with a family history of hypertrophic cardiomyopathy, chest pain with exercise, syncope or near syncope with exercise with this type of murmur should have a pediatric cardiology referral.

Ancillary tests

Ancillary tests are useful in the evaluation of murmurs, but should be ordered with an understanding of each test’s limitations. As a rule of thumb, when uncertain if a murmur is innocent or pathologic, a chest x-ray and electrocardiogram are good screening tools in this evaluation. An echocardiogram certainly is helpful, but should not be used as a screening tool. A pediatric cardiology referral and evaluation can prevent unnecessary testing, which certainly can lead to savings and promote optimal care. Recent studies have shown that there are hundreds of dollars in savings, per murmur evaluation, when a pediatric cardiology evaluation is done prior to requesting an echocardiogram. There are specifics in the murmur evaluation that may be picked up by a pediatric cardiologist, which would prevent unnecessary testing or, more importantly, promote a more precise ultrasound test to look for subtleties on an echocardiogram that may not be picked up with a general complete echocardiogram.

Improving skills

Multiple interactive murmur modules are available in CD, DVD and interactive CD-ROM formats at Children’s Memorial Hospital. These are available to the pediatric residents to improve their skills. In a recent study,[2] pediatric residents rotating through pediatric cardiology subspecialty significantly improved their auscultatory skills using interactive CD-ROMs as an adjunct to listening to patients. Most of these interactive tools [3,4] are available to the public and would be valuable to the primary care physicians unnerved or uncertain in their initial evaluations of heart murmurs.

Conclusion

The key to distinguishing innocent versus pathologic heart murmurs is to know the innocent murmur. Murmur characteristics need to be considered in terms of loudness, site of maximal intensity, timing, and qualities of sound. Recognizing the 4 groups of most common innocent murmurs found in pediatrics will help the primary care physician determine the need for further screening tests and referral to a pediatric cardiologist. An echocardiogram should not be requested prior to a careful evaluation of a murmur by a pediatric cardiologist.

REFERENCES

[1.] Zuberbuhler JR. Clinical Diagnosis in Pediatric Cardiology. Churchill, Livingstone, 1981.

[2.] Mahnke CB, Nowalk A, Law YM. Comparison of two educational interventions on pediatric auscultation skills. Pediatrics 2004 May;113(5):1331-1335.

[3.] Hoyt B, Roy DL. Ears On! A Cardiac Auscultation Teaching Program. CD-ROM. Cor Sonics, Inc., Dalhousie University, Halifax, NS Canada; 2001. Available at http://www.earson.com/who.html. Accessed January 25, 2006.

[4.] Lehrer S. Understanding Pediatric Heart Sounds. CD-ROM. Saunders, Elsevier Science; 2003.