THE "INCIDENTAL" SYSTOLIC MURMUR

(1)

THE

“INCIDENTAL”

SYSTOLIC

MURMUR

Arthur J. Moss, M.D.

From the Department of Pediatrics, UCLA School of Medicine, Los Angeles

DIAGNOSIS

AND

TREATMENT

T

HE CHILD with symptomatic heart

dis-ease is not generally much of a

prob-lem for the practicing pediatrician. He is promptly referred to a cardiac center or to

a pediatric cardiologist for further

evalua-lion. However, such is not the case with the

asymptomatic child in whom a systolic

murmur is heard incidentally during the

course of a routine physical examination.

This very COI111TUOfl event requires that the pediatrician decide in each instance whether the murmur can be safely ignored

or whether further studies are indicated.

For a detailed description of murmurs in childhood, the reader is referred to the

ex-cellent work of Castle and Craige.’

The overwhelming majority of systolic

murmurs discovered in asymptomatic

chil-dren are either innocent or are caused by a

ventricular septal defect. The present

dis-cussion is limited to the two most common

innocent murmurs, the vibratory and the

pulmonic ejection murmur, and their

differ-entiation from murmurs due to ventricular

septal defect, mitral insufficiency, and other

organic lesions. The venous hum, also a

fre-quently encountered innocent murmur, is

not included because it is easily

recogniz-able by the louder diastolic component, the

location over the base of the heart, and the

characteristic diminution in intensity or

complete disappearance with compression

of the neck vessels, with movement of the

head from side to side, or when the patient lies down. It is sometimes confused with

the murmur of patent ductus arteriosus;

but, because of the foregoing features and

because it is usually located parasternally

to the right rather than to the left, the

dif-ferentiation is not difficult.

INTENSITY OF MURMURS

For the purposes of this discussion, the

intensity of the murmur is graded in

accor-dance with the classification of Levine and

rv2 Grade I-very faint, audible only after a period of careful auscultation. Grade Il-faint but audible immediately.

Grade 111-of moderate intensity. Grade IV -loud and often accompanied by a thrill.

Grade V-extremely loud but cannot be heard with the stethoscope off the chest wall. Grade VI-extremely loud, can be heard with the stethoscope off the chest wall.

Since the intensity of the murmur is

in-fluenced by cardiac output, it is important to auscultate the heart with the child at rest

and while free of fever. Anything which

in-creases cardiac output

(

exercise, fever,

ane-mia, anxiety, hyperthyroidism, and so

forth) may intensify an existing murmur or even produce one. Conversely, the intensity of the murmur may almost disappear or completely disappear while crying because of the effect of the Valsalva maneuver on pressure relationships and blood flow. It is

also important to recognize that, in the very young infant, organic murmurs may

mi-tially be barely audible and reach Grade III or IV intensity only after several days or weeks. This results from the changing pres-sure relationships which arise from postna-tal transition of fetal to adult-type

pulmo-nary vasculature. With the development of the adult type of pulmonary vessels, the high pulmonary vascular resistance present at birth recedes, and shunts between the

two circulations may become larger.

THE VIBRATORY MURMUR

This murmur is commonly encountered in pediatric practice. The exact means by which it is produced remains uncertain. It occupies early and mid-systole, is maximal at the third and fourth left intercostal

spaces, and extends laterally to the apex of

the heart. It is of low or moderate intensity

ADDRESS: Department of Pediatrics, UCLA School of Medicine, Los Angeles, California 90024.

(2)

688 SYSTOLIC MURMUR

(not more than Grade III

)

and is

charac-terized by a uniform, low-pitched sound

which has been described as musical,

twanging string, fiddle string, or groaning

in character. This quality is best appre-ciated with the bell of the stethoscope.

Typically, the murmur diminishes or

disap-pears when the patient is examined in the upright position.

Occasionally, the musical quality is not detected and then the murmur may be con-fused with that of a ventricular septal de-feet or mitral insufficiency. In addition, the

murmur of cardiomyopathy with or without left ventricular obstruction may be of the

vibratory type and may be

indistin-guishable on the basis of auscultation from

the innocent variety.3

The murmur of the ventricular septal

de-feet, in its typical form, occupies all of sys-tole. It is generally Grade III or more, is widely transmitted, and is often associated

with a palpable thrill. In the event of spon-taneous closure, it may become progres-sively softer and limited more and more to early systole. With advanced pulmonary

hy-pertension, the murmur also may be fainter and may occupy only a portion of sys-tole. Such a murmur, when accompanied by a loud single second sound in the pulmonic

area, should make one suspicious of

ventric-ular septal defect with pulmonary hyper-tention.

The murmur of mitral insufficiency is blowing and high pitched in character and generally occupies all of systole. Less fre-quently, it may be limited to late systole. In

contrast to the vibratory or ventricular

sep-tal murmur, it is maximal at the apex or in

the axilla. This is the major differential fea-tare.

The murmur, which may be associated

with cardiomyopathy, often cannot be

dif-ferentiated on the basis of physical

exami-nation from a non-organic murmur or from a ventricular septal defect. This rare entity

is often associated with functional obstruc-tion of the left ventricle. It is insidious in

onset and often is not recognized until early

THE PULMONIC EJECTION MURMUR

This common, innocent murmur is due to turbulence in the outflow tract of the right ventricle, normally associated with right ventricular ejection. It is located in the see-ond or third left intercostal space

paraster-nally and is early to mid-systolic in time. It ranges in intensity from Grade I to Grade III. It results from any condition which causes an increase in pulmonary blood flow

(

anemia, fever, anxiety, exercise, and so forth). The identical murmur may be caused by an atrial septal defect or by mild pulmonic stenosis.

One should become suspicious of an atrial septal defect if the ejection murmur is

associated with a second sound in the

pul-monic area which is widely split and

re-mains so during expiration as well as

inspi-ration. The most important diagnostic

aus-cultatory feature is the presence of an early,

short diastolic murmur along the lower left

sternal border. When present, this murmur

is caused by increased flow through the

tn-cuspid valve

(

relative tricuspid stenosis).

A Grade I systolic murmur as an isolated finding

(

normal heart tones, no cyanosis, and so forth

)

can generally be ignored with relative safety. Many practitioners elect to disregard the vibratory murmur with the characteristic musical quality, rather than worry the family or put them to the

ex-pense of additional studies. Although the

practitioner may disregard the vibratory murmur, he should be aware of the calcu-lated risk (very small indeed

)

of

overlook-ing an organic lesion. A persistent Grade II

or III murmur of questionable origin is

in-dictation for an electrocardiogram and

tele-roentgenogram. If these are normal, the possibility of significant cardiomyopathy or atrial septal defect is pretty well excluded. Moreover, although a normal electrocar-diogram and teleroentgenogram are not in-consistent with mild puirnonic stenosis or mild ventricular septal defect, the risk in-volved in overlooking either of these is not great. Surgical intervention is not indicated

(3)

DIAGNOSiS AND TREATMENT 689

whether they would recommend operative closure of a small ventricular septal defect

(left-to-right shunt, less than 1.5: 1

)

in a

5-year-old child responded in the negative.’

This change in attitude arises from

increas-ing evidence of spontaneous closure.5 The major reason for the definitive diagnosis of mild pulmonic stenosis or of a small

yen-tricular septal defect would seem to be the

need for prophylactic antibiotics with

bacterial infections or surgical procedures

which predispose to bacterial endocarditis.

In the case of atrial septal defect, early rec-ognition is quite important because this

le-sion is ideally repaired at about 4 years of

age. A delay to adolescent or adult life may

be accompanied by a signfficant rise in

op-erative risk.

The murmur of mild pulmonic stenosis

may be indistinguishable by auscultation

from the innocent pulmonary ejection mur-mur or from that of an atnial septal defect.

With mild pulmonary obstruction, the see-ond sound in the pulmonic area is not

di-minished in intensity as it is in the more

Se-vere forms. Wide splitting, which varies with respiration, is said to favor the

diagno-sis of mile pulmonic stenosis, but this split-ting is often encountered in normal

chil-dren.

MANAGEMENT OF THE “INCIDENTAL”

SYSTOLIC MURMUR

It goes without saying that any child with a systolic murmur deserves the benefit of a complete physical examination. This

must include palpation of the peripheral

pulses, measurement of blood pressure in

both upper extremities and one lower

ex-tremity, and careful palpation and auseulta-tion of the heart. If the patient is febrile or

severely anemic, he should be re-evaluated

when in a state of normal cardiac output. A murmur with intensity of Grade IV or more is indication for an electrocardiogram and teleroentgenogram. The electrocardio-gram should include the three standard limb leads, the three unipolar leads, and

seven precordial leads

(

V3 in addition to V,-V6 ). A small precordial electrode must

be used and care taken not to smear the

electrode paste from one precordial site to

another. The tracing should be interpreted

by one thoroughly familiar with the criteria

as they apply to children.

The roentgenogram should be taken with

the tube about 6 ft from the body. A single posteroanterior view is usually sufficient. Fluoroscopy in the routine

roentgenograph-ic examination of the heart is not advisable because of the excessive radiation.

The question of which patients should be referred to a pediatric cardiologist depends upon the competence and experience of the

pediatrician. If he can establish with confi-dence that a child has an innocent murmur,

then, of course, there is no need for consul-tation. If he is confident that the child has

mild pulmonic stenosis or a small ventricu-lar septal defect with unequivocal normality of the electrocardiogram and teleroentgen-ogram, he would not risk much by contin-ued observation. In general, it would seem wise to seek consultation for all children in whom there is reasonable suspicion that an organic lesion might be present.

REFERENCES

1. Castle, R. F., and Craige, E. : Auscultation of the heart in infants and children. Pr.rwrmcs, 26:511, 1960.

2. Levine, S. A., and Harvey, W. P.: Clinical Aus-cultation of the Heart. Philadelphia: W. B. Saunders, p. 196, 1949.

3. Bloomfield, D. K., and Liebman, J.: Idiopathic

cardiomyopathy in children. Circulation,

27:1071, 1963.

4. Moss, A. J.: Conquest of the ventricular septal defect . . . . A period of uncertainty. Amer. J.

Cardiol., in press.

5. Bloomfield, D. K. : The natural history of yen-tricular septal defect in patients surviving in-fancy. Circulation, 34:914, 1964.

6. Liebman, J.: Electrocardiography. In Moss, A. J., and Adams, F. H.: Heart Disease in Infants,

Children and Adolescents. Baltimore: Wil-hams and Wilkins, pp. 199-220, 1968.

7. Adams, F. H., and Rigler, L. C. : Reduction of

(4)

1970;45;687

Pediatrics

Arthur J. Moss