Characteristics of the Unipolar Precordial

Electrocardiogram in Normal Infants

By ROBERT F. ZIEGLER, M.D.

The electrocardiogram should have as much clinical value in infants and children as in adults. Suchvalue, as in adults, must depend upon an accurate knowledge of normal standards which changeprogressively during infancy and early childhood. Some of the more important measurements in theprecordial leads of normal infants are presented and discussed. These measurements, the ampli-tude and the time of inscription of the intrinsic deflection, are believed to indicate the changingrelationship between the mass of the right and left ventricles, and on the basis of these data it isalso believed that an earlier and more accurate diagnosis of ventricular hypertrophy can be made atany age.

R ECENT interest in the various formsof congenital and acquired heart dis-ease in infants and children, coupled

with a complete lack of adequate standardsfor the normal electrocardiogram in these agegroups, has made apparent the need for thesort of study which will provide useful knowl-edge about this important method of examina-tion. Heretofore little interest has been giventhe subject of electrocardiography in children.In fact, even the current literature is unfor-tunately replete with statements of the limita-tions and lack of value of this type of data inevaluating the cardiac status of infants andchildren. It seems probable that this attituderesults from a lack of knowledge rather than aspecific limitation in the value of the methodand should consequently be dispelled by ade-quate investigation. A detailel study of theelectrocardiograms of 650 normal infants andchildren has already been made and is beingpublished separately.' It has been suggestedthat in addition to the original material a briefsummary of the most important characteristicsof the precordial electrocardiogram in infantsand young children might be of supplementaryvalue. It is therefore the purpose of this com-munication to present an abstract of this ma-terial which will include data pertaining to theform and measurements of the ventricular de-flections in unipolar precordial leads of infantsand children from birth to the age of three

From the Cardio-Respiratory Division, Depart-ment of Medicine, Henry Ford Hospital, Detroit.Mich.

438

years (table 1). It is assumed, probably cor-rectly, that the extremity leads of the electro-cardiogram are of less value than those fromthe precordium. These will consequently not bediscussed in the present paper.The two most important practical aspects of

the precordial electrocardiogram in normal in-fants are (1) the form of the QRS complexesin leads from the right and left sides of theprecordium, particularly as this pertains to the

TABLE 1.-Distribution of Cases According to Age.

Age

Birth-24 hours...................1-7 days............................7-30 days................1-3 months..............3-6 months ...............6-12 months ......... .........

1-3 years ...................

Total ............................

Number of cases

20262515141827

145

detection of an abnormal degree of right or leftventricular hypertrophy in this age group, and(2) the direction and configuration of the Twaves in each of the precordial leads, as theypertain to the detection and evaluation ofvarious types of cardiac abnormalities.With regard to the first of these two prob-

lems, it has formerly been considered that inthe extremity leads right axis deviation con-stitutes evidence of right ventricular enlarge-ment, and more or less parallels anatomicmeasurements of relative right ventricular mass

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ROBERT F. ZIEGLER

in normal infants. The limitations of this elec-trocardiographic criterion have been dis-cussed elsewhere and need not be repeatedhere. Supposedly more accurate criteria, de-rived from measurements in the precordial

cordial leads expressed as a percentage of theamplitude of the RS deflection in the samelead.

2. The time of onset of the RS deflection inthe precordial leads, measured from the be-

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FIG. 1. The amplitude of intrinsic deflection in unipolar precordial leads expressed as a percentageof RS in the same lead. Each group of six points represents measurements for each of the precordialleads V, through V6. Note the progressive changes during the period of early infancy and the compari-son with the adult pattern attained at the age of about 12 to 16 years. (All figures are reproduced bythe courtesy of Charles C Thomas.')

FIG. 2. The time of onset of the intrinsic deflection in precordial leads measured from the begin-ning of QRS in simultaneous standard lead I. Each group of six points represents measurements foreach of the precordial leads V, through V6. Note the progression of changes during early infancy andthe relation to the adult pattern reached between age groups of 12 to 16 years.

lead electrocardiogram, have also been dis-

cussed in the original publication' and may be

applied to an analysis of the electrocardiogramsof normal infants and children. Among these

are the following important measurements:

1. The amplitude of the R wave in the pre-

ginning of QRS in simultaneous standardlead I.As observed in figures 1 and 2, well marked

changes in these measurements are apparentwith age. If, as seems reasonable, they repre-sent some relation between the size of the two

so

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UNIPOLAR PRECORDIAL ELECTROCARDIOGRAM IN NORMAL INFANTS

ventricles, then it may be concluded that thereis evidence that the right ventricle is normallylarger in comparison with the left from birthto the age of 1 to 3 years than in older childrenand adults. It may also be seen that the twosets of measurements parallel each other ratherclosely. Various electrocardiographic studieshave utilized similar measurements as criteria

TABLE 2.- The Per Cent Incidence of Various T-WavePatterns froon Birth to the Aye of 3 Years

0-24 hours +

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74.1 74.17.41 3.70 3.718.5 18.518.75 18.7:62.5 62.50 6.2518.75 12.50 2583.5 33o 016.5 4211.5 19.277.0 61.63.8 07.7 19.20 21.5

100 64.50 00 140 0

100 910 00 90 4.396 77.50 04 18.2

V3 V4 V5 V6

140.0 59.3 46.6 55.740.0 22.2 13.4 14.80 7.41 0 3.720.0 11.1 40.0 25.9

i27.3 56.2 100.0 87.536.4 25 0 00 6.25 0 6.25

36.4 12.5 0 6.2531.3 100 1100.0 10025.0 0 0 06.25 0 0 037.5 0 0 012.5 80.8 100.0 10012.5 7.7 0 00 0 0 075.0 11.5 0 012.5 100 100.0 10012.5 0 0 00 0 0 075.0 0 0 00 73 100 100

57 4.3 0 00 0 0 0

43 22.7 0 015.4 92 100 10038.4 4 0 00 0 0 0

46.2 4 0 0

for right or left ventricular hypertrophy, butno such criteria have as yet been available forthe rapidly changing phases of infancy andearly childhood. It would appear evident on

the basis of such data as summarized here andpublished in more complete detail in the refer-ence citedi that abnormal degrees of right or

left ventricular enlargement should be detect-able with reasonable accuracy at any age andprobably even with early degrees of enlarge-ment. As will be shown in subsequent publica-tions, these electrocardiographic criteria have

actually made it possible to detect the presenceof single chamber enlargement during infancyand childhood with greater accuracy than con-ventional roentgenographic methods and at atime when the latter may reveal completelynormal findings.The second problem is that concerneI with

the description of the direction and configfura-tion of the T waves in the precordial leads. Aninterpretation of these observations is notwithin the scope of the present study. It mightfirst be stated that current concepts of the pre-cordial T wave pattern in normal infants andchildren have been somewhat in error becauseof such technical difficulties as the failure toisolate carefully each exploring point over theprecordium and the use of bipolar instead ofunipolar precordlial leads. Preat care was ex-ercised in the present study to insure thetechnical accuracy of each record. The mostinteresting feature of the precordial T' wvav.epattern in normal infants is the seoluence ofchanges which occuir independently of anycomparable changes in QIRS during the firstthree or four d(ays of postnatal life. DIuringthe first 24 hours after birth the T waves areusually uplight in lead Vi and inverted inleads V5 and V6. During the next 48 to 72hours there follows a progressive inversion ofthe T wave-_s in leads V, and V2 and elevationof those in leads V5 and V6. While the physiologyunderlying these phenomena remains unknownfor the present, the practical clinical implica-tions are apparent. In particular, the samine typeof change has been observed in someshat ex-aggerated form and with a longer duration ininfants born to diabetic mothers and in infantswith congenital defects which impose a primaryincreased work load on the left side of the heart.The characteristic T-wavce pattern in the pre-cordial leads of older infants and young childrenconsists of slight to moderate elevation of theS-T segment with multiphasic or inverted Twaves in leads from the right and mid pie-cordium and upright T waves in leads fromthe left side of the precordium. The directionand configuration of the precordial T waves inthese age groups are indicated in table 2.

It seems apparent that the accurate differ-entiation of the normal and abnormal heart in

1 vwk.-

1-3 mos.

3-6 mos.

6 mos.-1

1-3 yrs.

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ROBERT F. ZIEGLER 441

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FIG. 4. The electrocardiogram of a baby without other evidence of heart disease born to a diabeticmother. The upper tracing in each figure is as labeled; the lower one is simultaneously recorded stand-ard lead I. Note the sequence of T wave changes comparable to those seen in early infancy in normalbabies.

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ROBERT F. ZIEGLER

infancy and early childhood as well as the exactdiagnosis of cardiac defects in this age groupdepends upon the recognition and proper evalu-ation of just such ventricular patterns as thosedescribed. Two sets of electrocardiogramsdemonstrating the characteristic patterns of anormal infant and a baby without later evi-dence of heart disease born to a diabeticmother are shown in figures 3 and 4.The clinical implications of these electro-

cardiographic findings in normal infants andchildren deserve further comment. It has al-ready been emphasized that one of the mostimportant practical applications of these datais the accurate and early detection of singlechamber enlargement as well as the recognitionof other specifically abnormal ventricular pat-terns. An important corollary of the improveddiagnostic accuracy resulting from this knowl-edge of the electrocardiograms includes, in ad-dition to a better ability to establish a differ-ential clinical diagnosis, greater knowledgeabout the natural history of congenital cardiacdefects together with an improved perspectiveof problems relating to their prognosis andtreatment. As an example, the exact knowledgethat a certain degree of left rather than rightventricular hypertrophy is present in an infantwith a noncyanotic congenital malformationof the heart may help confirm the clinical diag-nosis of patent ductus arteriosus long beforeother so-called "typical" findings become man-ifest. This in turn will have at least two ad-vantages. It will, in the first place, make possi-ble definitive therapy if necessary and by sodoing may frequently save a life which mightotherwise be lost. It will also provide informa-tion necessary to a more complete understand-ing of the basic problems involved in thenatural history of this defect. These would in-clude such problems as the relationship be-tween the size of the ductus and the degree ofleft ventricular hypertrophy, the relationshipbetween compensating or complicating pul-monary hypertension and the size of the rightventricle, the significance of increasing heartsize and others. Similar importance of the elec-trocardiogram could be discussed for all thevarious forms of congenital cardiovascular de-fects.

A number of other important applications ofthis study of the electrocardiograms of normalas well as abnormal infants and children whichconstitute the subject for further investigationand report may be listed to include the fol-lowing: (1) The evaluation of so-called border-line electrocardiographic patterns, such asthose involving intraventricular conduction de-fects. (2) Detailed investigation of the formand significance of the initial ventricular de-flections. (3) The recognition and the evaluationof so-called physiologic and other degrees ofright bundle branch block. (4) The determi-nation of the significance of intraventricularconduction defects in the development of electro-cardiographic patterns of ventricular hyper-trophy. (3) The evaluation of the significance ofunstable electrocardiographic patterns.These all constitute the subjects for other

papers being prepared for publication

SUMMARY

The principal characteristics of the ventric-ular deflections in the unipolar precordialelectrocardiogram of normal infants from birthto the age of 3 years are described briefly.More complete details have been publishedelsewhere.' These characteristic features in-clude: (1) evidence of a normal degree of rela-tive right ventricular prepondrance, consistingof large amplitude and late onset of the in-trinsic deflection in leads from the right side ofthe precordium; (2) the presence of upright Twaves in leads from the right side and invertedT waves in leads from the left side of the pre-cordium during the first 24 hours of life, fol-lowed by a gradual progression to inverted Twaves in leads from the right side and uprightT waves in leads from the left side of the pre-cordium during the subsequent two to fourdays; and (3) the presence of multiphasic orinverted T waves in leads from the right andmid precordium in older infants and youngchildren. The practical clinical significance ofthese various precordial ventricular patterns isemphasized.

REFERENCEZIEGLER, R. F.: Electrocardiographic Studies inNormal Infants and Children. Springfield, Ill.,Charles C Thomas. In Press.

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ROBERT F. ZIEGLERCharacteristics of the Unipolar Precordial Electrocardiogram in Normal Infants

Print ISSN: 0009-7322. Online ISSN: 1524-4539 Copyright © 1951 American Heart Association, Inc. All rights reserved.

is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Circulation doi: 10.1161/01.CIR.3.3.438

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