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Use of Tape-Recorded Heart Sounds inScreening of Children for Heart DiseaseBy JACQUES M. SMITH, M.D., ROBERT A. MILLER, M.D.,CARL MARIENFELD, M.D., BETTY HAHNEMAN, M.D., AND

JOEL WILLARD, B.S.

An automated tape-recording unit for use in screening large populations of schoolchildren for heart disease has been developed and field tested. A technician can producegood quality apex and base heart sound recordings from 250 children during an average

school day. The physician can listen to these recordings at a rate of 140 children per

hour, recalling for examination each child considered to have an abnormal recording.Since almost all heart disease in children has some acoustic manifestation, a screeningtechnic based on the heart sounds seems to be a logical one. The studies done with thisunit have demonstrated its ability to select children with heart disease from a largenumber of normal children. Agreement between readers is satisfactory, and the numberof "false positives" is considered reasonable.

T HE recent dramatic progress in the diag-nosis, treatment, and surgical correction

of heart disease has stimulated renewed in-terest in the prevalence of cardiac problemsin the school-age child. The practising physi-cian has become increasingly aware of con-genital heart disease, so that at the presenttime these malformations are thought to con-situte at least half and probably more thanhalf of the total cases of heart disease inchildren." 2

Various cities in the United States main-tain registries of heart disease in children,especially rheumatic heart disease; but inmost instances these cases represent a rela-tively small proportion of the actual numberof affected children.

There are over 25 published studies on theincidence of heart disease in school children(table 1), 5 of which have appeared since1945.3-11 These studies are based on clinicalexamination by workers with widely variedtraining and experience. The older studiestend to show a higher over-all incidence ofheart disease and a marked predominanceof rheumatic heart disease. More recentstudies show lower incidence and a moreeven distribution of the cases between con-

A project of the Children 's Screening Committeeof the Chicago Heart Association.

genital and acquired heart disease. The scopeof all these studies was limited to relativelysmall numbers of children by the laboriousand time-consuming technic of physical ex-amination as applied to large numbers ofindividuals.On the basis of the published data one

may make 2 assumptions: 1. There are prob-ably 4 or more cases of heart disease inevery 1,000 school children. 2. In many ofthese cases neither the parents nor the familyphysician of these children is aware that theyhave heart disease.The nature of heart disease in children is

such that it almost always alters the charac-teristics of the normal heart sounds or pro-duces a murmur. The very high incidence ofsignificant murmurs in heart disease of child-hood is in direct contrast to the situation inadults, in whom a large proportion of coro-nary and hypertensive heart disease occurs.It would seem, therefore, that the mostlogical approach to cardiac case-finding inchildren would lie in the field of auscultation.Phonocardiography or other graphic methodsof registering the heart sounds of childrenhave been shown to be unsatisfactory as a

screening device for heart disease.20 Thehigh incidence of innocent murmurs in child-hood and the problem of extraneous noise

Circulation, Volume XX, November 1959887

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SMITH, MILLER, MARIENFELD, HAHNEMAN, WILLARD

TABLE 1.-Incidence of HeartChildren`

Disease in School

0

.0.8'a9ej.a1

New York City, 1915New York City, 1918New York City, 1918 to 1922New York City, 1921Chicago, 1923Philadelphia, 1924Chicago, 1924Chicago, 1925Boston, 1927Philadelphia, 1929Florida, Illinois and

Missouri, 1929Cincinnati, 1927Rochester, Minn., 1931New York City, 1931

New Haven, 1934Better School '

" Poorer School"

Philadelphia, 1937Elementary

High School

San Francisco, 1938

Cincinnati, 1938

Louisville, 1941

Denver, 1945

Iowa, 1946

San Francisco, 1948

278.174250,000

1,336,34344,000

158,82623,671

1a3,671130,260119,3310,333

17,9746,9601,3282,691

4i

A4)o0

1.50

1.60

1.39

0.50

0.90

0.63

1.50

1.70

0.52

0.91

1.00

0.37

0.70

1.10

Gradein school Children

1 1,144 1.325 1,123 1.42

1 1,863 1.935 1,628 2.08

33,293 0.500.30*

9,154 0.900.40*

13,338 0.37

85,389 0.360.12*

41,905 0.52

1.09

5,058 0.4757,768 0.44

*Possible heart disease.

limit the value of these technics when usedalone. Clinical auscultation, on the other hand,is extremely time-consuming. In addition, ithas been shown that there is much variabilityin the detecting and interpreting of heartmurmurs among various examiners.20 Thegreat advantage of auscultation, as Rushmerhas pointed out, is that it apparently in-

volves "those characteristics of auditory per-ception that allow a person to recognize afamiliar voice even when distorted by a tele-phone."' This subjective advantage over thephonocardiogram, plus the ability to screenout other noise, are the advantages of aus-cultation.20 It seems, therefore, a technicthat retains the advantages of auscultationbut is efficient enough to allow a few trainedobservers to screen rapidly large numbers ofpatients under rather standard conditionswould be an ideal case-finding technic.The tape recording of the heart sounds21' 23

has several distinct advantages over physicalexamination is mass-screening programs: 1. Itdoes not require the presence of the physi-cian. The recordings may be made by atrained technician. 2. Large numbers ofchildren can be recorded on a single roll oftape, which in turn can be played back atthe listener's convenience in a quiet room. 3.The listener can turn the volume up or downand can go back to a case that he is not sureabout. 4. A permanent record of these heartsounds is available, so that in questionablecases a phonocardiogram may be made fromthe tape giving the advantages of both sub-jective and objective evaluations.Normal auscultatory findinlgs in children

differ greatly from those in adults.24 Bothheart sounds are louder and the incidence offunctional murmurs is very high in children.Examiners not acquainted with "this charac-teristic ability to 'hear better' are in dangerof over estiinatinga the auscultatory find-ings. ''24 At rest, a faint systolic murmur canlie recorded by the phoinocardiogram in allchildren.24 With sufficiently sensitive pick-ups one can record a systolic murmur inall normal 20-year-old subjects.21 Directphonocardiography reveals a systolic mur-mnur in or over the pulmonary artery in allcases.21 Maunheimer has shown in a studyof normal children that about half of theseimunocent murmurs are too faint to classifyeven by phonocardiography.24 Most of thefunctional murmurs of reasonable loudnesshave the familiar musical, vibratory, twang-

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TAPE-RECORDED HEART SOUNDS

ing string quality described by Still at thebeginning of the century.25 The rest of thesefunctional murmurs are those of the ejectiontype, soft systolic murmurs usually bestheard in the second left interspace, wellseparated from the heart sounds, and asso-(iated with normal splitting of the secondsiound.24' 26 These innocent murmurs becomeas familiar as old friends to experienced ex-aminers of large numbers of normal children.The heart sounds and murmurs in congenitaland acquired heart disease in almost everycase differ remarkably from innocent mur-murs in quality, frequency, amplitude, andtiming.26-28 There is a small group of pa-tients in which auscultation alone is insuffi-cient to make a definite determination be-tween innocent and pathologic murmurs.15' 19Also, a few cases of congenital and acquiredheart disease have practically no ausculta-tory manifestations.The use of heart sounds as screening mate-

rial for the detection of heart disease inchildren, therefore, will create a group of"false positives, " which include innocentmurmurs of unusual quality or loudness,those in which the differentiation betweenorganic and innocent murmurs cannot bedetermined from the sound, and those casesin which for various reasons the heart soundsthemselves seem unusual. Also, a group of" false negatives,'" including such things asan occasional case of coaretation of the aortawithout a murmur, some cases of myocar-ditis or hypertension, might be missed byauscultation alone.

In the past few years it has become pos-sible to reproduce heart sounds and murmursas they are heard through the stethoscope.With this in mind, a study was begun in1954 to investigate the feasibility of usinghigh-fidelity tape-recording equipment inscreening for heart disease in children. Toinvestigate the ability of the readers to rec-ognize abnormal auscultatory phenomenafrom tape recordings, a group of 100 pa-tients was recorded. Some had congenital oracquired heart disease, and others had nor-

TABLE 2.-Results of Pilot-Recording Study

cc

~~a ~ ~ ~ 0~

Test C od . A

(a) (b) (c) (d) (e)

Heart sounds 2,923 264* 85* 349 24.3

Reading x-rays for 1,714 69 24 93 25.8tuberculosis

*Uncertain readings are included as positive.

mal hearts; but in every case cardiac cathe-terization, x-ray of the chest, and electro-cardiogram were done. The cases with knownheart disease all had organic murmurs. With4 readers listening to the recorded heartsounds, no case of heart disease was missed,and every "normal" recording was recog-nized. Next, the heart sounds of 1,200 chil-dren were recorded at the Cook CountyChildren's Hospital and in 5 Chicago ele-mentary schools. These recordings were re-viewed by 3 physicians: a pediatric cardiol-ogist, an adult cardiologist, and an internist.The prime object of this study was to deter-mine the degree of agreement among thereaders. The results are shown in table 2.Any 2 readings of the 1,200 recordings pro-vided 1,200 comparisons. Since there were 3pairs of readings, reader A and B, readerA and C, and reader B and C, a total of3,600 comparisons was available from whichto determine reader agreement. Actually,only 3 272 were analysed for agreement andare shown on table 2. As can be seen, evenwith equipment considered at the time inade-quate and with readers with quite differentkinds of training, the degree of agreementwas about as good as that demonstrated bypairs of readers of miniature chest x-rays.30In an attempt to improve agreement amongreaders a teaching roll of heart sounds was

developed. This preliminary study alsopointed up the need for (1) modification ofthe equipment in order to speed up the

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SMI TiI, M\1 ILLER, MARIENFELD, HAIINEMIAN, WHILARD

FIG. 1. Automatic tape-recording unit used in screening project. See text for description.

recording. rate, (2) sini)lification of the tech-nical job of making the recordings so as tolessen technician fatigue, and (3) simplifica-tiOl of the administrative )roIblems of mass-

screening projects such as the identificationof the patients and the inaiintenciance of goodre('ords. This study- also showed a need forimprovemient in the quality of the re-

corded sounds, specifically ini the micro-

phone, poinlte(l u) the problems of varyingvolume depending onr the thickness of thechest wall, the size of the children, the ireedfor reduction of room noise, and the diffi-(nulty of elininating alternating current humiii the varying circumstamnces of recording inlifferent locations.

METHODS AND MATERIAL

The recorder (figs. 1 and 2) was a Berlant BAXautomatic nIodified by replacing power suppliesto use direct current from a battery pack for the"A" supply (1.iA), and an especially built highly

filtered AC/1)C power sulply (15B) for the "B"source (1B). Additional muiodificatiois of the cir-cuitry reduced noise and permiIiitted operation ofthis receorder with associated e(fuipment. The re-

cording rate was 71/2 inches of tape per second,and the frequency response of the unit was plusor ilnnnus 3 db. from 30 to 10,000 cyeles.A Berlait 4-channel mixer. (2), immodified by the

installation of remotely operated relays in eachof the input chaniels, was used to (cointrol volumeand to iiix the incominig signlals which identifiedthe position of the microphone on the chest, theaudio-ainnounced identification number of the pa-tient, and the heart sound signal. The frequencyresponse of this mixer matched that of the recorder.An automatic volume contiol (3) nina imitained

the signal level of the amplified heart sounds with-in a pre-set range without tine necessity for theoperator to adjust constanftly the recording vol-unine.

Tine microphone (4) was a crystal type with a

frequency response of plus or mllinlus 1 db. from2'6 to 1,500 cycles per second.The microphone was encased in an aluiminuimi

cup-shaped holder (5) connected to a vacuum

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pre

7B recorded _ __id.

number

cord IA7 A number -recordin

amp.

visual

7 C ndmtbex c- - -

;ndicotor tone

16main power control

I B + supply | 158

A batterieschargerI15A

"A"battery ...jeliminatorl

apex tone base tone

8 9

Hc~ording

J L_6A[

vaCu ur

unit control heart micdvacuum

L pump

storage

I 6

loal start| remote start

Il

power audio vacuum

FIG. 2. Equipment block diagram.

storage tank (6). When the microphone andholder were placed against the chest, vacuum suc-

tion held the microphone in position at the prede-termined pressure. It relieved the operator of thetask of holding the microphone, eliminated thenoise generated by the fingers of the operator andthe movements of the skin of the subject, andserved to block the majority of room noises. Themicrophone pressure control helped to eliminatethe distortion caused by excessive pressure on themicrophone diaphragm. The vacuum was releasedautomatically, at the completion of a recording bya relay, a solenoid valve and a microswitch thatlocked into a specially built automation unit. Avacuum gage, power switch, and selector switchwere provided so that the unit might be operatedeither manually or automatically.The children being screened were identified in 2

ways. A Simplex electric numbering machine(7A) was used to stamp identifying numbers on

the subjects' identification cards. It was modifiedto stack the cards automatically after they were

stamped and to operate with a 16-mm. magneticfilm (7B), a prerecorded series of consecutiveidentification numbers in the same sequence as thosenumbers stamped on the identification cards bythe numbering machine. The listener, therefore,

heard the patient identified by number and couldbe sure that that patient was correctly identified bya similarly numbered card.A solenoid-operated Veeder-Root counter (7C)

was interlocked with the numbering machine toprovide the operator with a visual indication ofthe number of the case being recorded.The listener was always aware of the position

on the chest from which the recording was madeby a one-half second, 1,000-eycle tone (8) recordedon the tape to indicate the apex recording. A sim-ilar 400-eycle tone (9) indicated the base of theheart. Two transistorized tone generators con-

trolled by a microswitch in the automation unitprovided the signals.The automation unit (10), which was designed

especially for the task, controlled the entire se-

quence of recording. The unit was activated bya foot switch (11). Ten microswitches activatedby milled cams on a common shaft controlled thesequence of timing during the recording cycle. Thetechnician placed the microphone in its vacuum

holder over the apex of the heart, and stepped on

the foot switch. The machine now automaticallystarted the tape-drive mechanism on the tape re-

corder and activated the recording bias, turned off

the vacuum pump motor, and opened the solenoid

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valve to furnish a vacuum for the microphoneholder. It then selected the musical tone that iden-tified the apex microphone position and fed thesignal to the tape, activated the card numberingmachine, and stamped the cards automatically withthe identification number, then activated the 16-mm. film play-back machine, which announced thesame number on the tape. The microphone wasnow activated and recorded 11 seconds of heartsounds at the apex. The unit now automaticallyshut off the tape recorder and released the vac-uum to the microphone holder. The techniciansaw that the microphone had been released fromthe chest and had only to pick it up and place itover the second left interspace, then stepped onthe activating foot-switch again. The automationunit started the cycle again, this time, however,identifying the recording as conming from the baseof the heart by the other musical tone. It thenbypassed the subject-numbering machine, sincethis second recording was from the same person.The entire recording cycle, apex and base, was 25seconds in length. The technician was suppliedwith monitoring speaker (12), a power amplifier(13) and a pair of Cambridge stethoscope-typeearphones (14), so that he could cheek the qualityof the recordings. The entire unit, with its bat-tery power supplies (15A and 15B) and controlpanel (16) was housed in 2 specially designedportable consoles, each of which divided in halffor easier portability.The recording team consisted of the recording

technician and an administrative aid. Arrange-ments were made for additional help with thedressing and supervision of the children from theschool nurse or other volunteers. Prior to the dayof the recording, information was supplied to theparents, informing them of the screening procedureand requesting permission to make the recordingson their children. For each schoolroom a mastersheet was prepared, which included the names ofall the children and indication whether permissionhad been granted for recording. Each child was

given his identification card and his presence wasnoted on the master sheet. As the individual wasto be recorded, he handed his identification cardto the administrative aid, who placed it in theSimplex stamping machine, which automaticallynumbered his card during the recording procedure.The child undressed to the waist and lay down.The technician then placed the microphone over

the apex of the heart and activated the automationunit. With the recording sequence it was possibleto record 2 children per minute. However, 60children per hour was a more reasonable rate andthis should be modified to account for delays in

bringing children to the equipment. Taking intoaccount the necessary adjustments to meet schoolschedules, we have found that over an extendedperiod of time a recording rate of about 250 to300 children per school day was quite practical.

Play-Back ProcedureIt has been found that a training period is neces-

sary for the listener to become proficient. Thetraining was provided by means of a training reelthat allowed the listener to become familiar withthe identifying tones of the microphone position,the quality of the heart sounds, murmurs, breathsounds, and the identification voice. In addition,it allowed hini to listen to normal and abnormalheart sounds and murmurs in rapid sequence andto familiarize himself with the characteristics ofthese sounds as heard through a speaker or ear-phones. This training reel was made up of record-ings selected from a group of 100 proved cases ofcongenital and acquired heart disease and from agroup of normal children.

Following this period of training, the listenerfound that a recording of 11 seconds at the apexof the heart and 11 seconds at the base was of ade-quate length for screening purposes without caus-ing undue fatigue. The normal screening rate fora trained listener was 140 patients per hour. Formaximum efficiency, we have found that listeningsessions should not exceed 1 hour. As he listenedto the tape, the physician used an electric addingmachine to record his results. The subjects iden-tification number was indicated in the hundredsand thousands column. The presence or absenceof murmurs or the inability of the reader to inter-pret the heart sounds because of technical difficul-ties was recorded in the tens column. The dispo-sition of the case, that is, recall for examination,no recall, or inability to decide because of technicaldifficulties was recorded in the units column.

Findings (in tens column)0-no murmur5-technically unsatisfactory9-a murmur present

Disposition (in units column)0-no recall5-no decision because of technical diffi-

culties9-recall

In addition to the "9," the subtract button wasused to put a dash behind a recall indication. Thishelped to prevent errors by requiring the readerto perform 2 different and distinct acts in indi-eating a recall and also simplified the finding ofrecalls in a long column of figures.

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Examples279 00 (case 279, no murmur, no recall)280 90 (case 280, murmur, no reeall-reader

considers murmur innocent)281 99 (ease 281, murmur, recall)282 55 (case 282, recording technically unsat-

isfactory, no decision could be made)It should be stressed that the physician listening

to the tape was not trying to miake a diagnosis.He was attempting, from a rapid sequence, to pickout those patients that should be recalled for ex-ainnation.

Field StudiesA number of studies have been conducted

for the purpose of testing the componentsof this equipment and the administrativeefficiency of the operating procedure.

Field Study No. 1. At a local privateinstitution, 99 children were examined (aus-cultation only) by each of 3 members of thescreening team. Heart sounds of these same

children were recorded in an area separatefrom the examining room. The recordingswere studied twice by each of the 3 physi-cians. once using Cambridge stethoscope-typeearphones for the play-back of the tape, andonce using a speaker in a quiet room. Thephysicians worked independently and theirfindings were not revealed to each other dur-ing the studies.Approximately 30 days after this recording

session, each of the children was re-examinedThis time, however, the 3 examiners actedas a consulting team examining the childrentogether. In addition, they had the resultsof 70-mm. chest x-ray and the medical his-tory of the child. On the basis of this exam-

ination, the physicians arrived at a "con-ference finding" for each child. These con-

ference findingss classified the children as

having normal or abnormal heart sounds andconstituted the standard against which thetype recordings could be compared (table 3).The number of false positives was relativelysmall, and no case of actual heart diseasewas missed by the screening technic. The

efficiency of the screening physician usingtape recordings was equal to that from hisauscultation.

TABLE 3.-Conference Findings in Ninety-nine Cascs

Tape Tapevia via

Reader Live speaker phones

Cases recalledA 4 6 5B 6 4 4C 6 5 6

4 Definite heart disease, 2 cases requiring furtherobservation, 93 no heart disease.

Field Study No. 2. In this study, a record-ing technician taped the heart sounds of 507children from a local foundling home.

These tapes were listened to by 4 of usand, oin the basis of the play-backs, 16 ofthe children were recalled. These were subse-(luenltly examined by 3 of us, and 1 childwas found to have definite heart disease. Twoother children had murmurs which wethought were probably not significant butwould require additional laboratory andclinical observation.

It was not until after these studies werecompleted that the participating physicianswere informed that this particular schoolcarefully excludes children with heart dis-ease. The one child, found by the screeningtechnic to have signlifieamlt heart disease, wasa known case in which the school had madean exception. There are 2 observations thatmay be made from this study. The rate offalse positives (15 out of 507 children) 2.6per cent seems to be a reasonable figure. Al-though there wsas only 1 case of heart dis-ease in the entire group, or an incidence ofapproximately 0.2 per cent, the case was notmissed by the screening technic.

Field Study No. 3. The heart sounds of1,020 children were recorded in a local ele-mentary school. The tapes were read by 3physicians and the results of these readingsare shown in table 4. The children recalledby the screening program were subsequentlyexamined by the same 3 physicians.The significanit findings in this project

were that out of 1,020 children 40, or 4.0per cent, were recalled. Of these children, 7were found to have definite heart disease.

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SMITH, MILLER, MARIENFELD, HAHNEMAN , WI LLARD

TABLE 4. Results of Tape RecordingsField Study No. 3

Total recorded on tape 1,020Total recalled 40Referred for follow-up care 101. Definite heart disease 72. Probably normal, buit need

further observation 3

Three other children warranted further fol-low-up because a decision could not be madefrom the murmur alone.

Therefore, 17.5 per cent of the recalls were

found to have definite heart disease, and a

total of 25 per cent of the recalls warrantedfollow-up study by their physicians. Anotherimportant fact is that of the 7 children foundto have heart disease, there was knowledgeof this in only 2. Neither the parents nor

the family physician knew of the existingheart disease in the other 5, even though a

periodic physical examination is required ofall students in the public schools. Further-more, this incidence of 7 cases of heart dis-ease per 1,000 is in agreement with publishedsurveys. These figures vary from about 4 to15 per 1,000 in the school age group.

DISCUSSIONAside from any other uses of this tape-

recording technic, its value in a case-findingprogram should be clear. In an era whenevery child with rheumatic heart diseaseshould be on prophylactic antibiotics andevery child with congenital heart disease isconsidered a potential surgical candidate, a

practical case finding method is needed. Thereports of Robinson,19 who found 4.4 cases

of heart disease per 1,000 in the San Fran-cisco schools, Rauh,15 who found 5 cases per1,000 in the Cincinnati schools, Weiss,16 5per 1,000 in Louisville, and Jackson,18 5 per1,000 in a rural Iowa county are only a fewof the mass of data testifying to the largenumbers of children with heart disease inour school system. There are probably 2,500to 5,000 schoole-age children with heart dis-

ease in Chicago alone. It is not feasible to

have a trained cardiologist examine hundredsof thousands of normal children in orderto screen for eases of heart disease. We can,however, bring the children to the cardiologistvia the technic of high-fidelity tape-recorded heart sounds. With the installationof this recording equipment in a sound-prooftrailer, it would seem quite practical to sur-vey large populations of school children forheart disease, in a way quite comparable tothe mass x-ray surveys for tuberculosis.We are quite aware of the potential psy-

chological problems that might be createdby recalling a normal child for cardiac evalu-ation. It should be possible to keep this ata reasonable minimum with proper educa-tional material for the parents, the teachers,and the children. The relatively low recallrate of false positives, approximately 30cases per 1,000, will also tend to obviate thisproblem. More important, however, has beenthe gratifying experience of the screeningphysician in being able to free the normalchild sentenced to limited activity because oferroneous diagnosis of heart disease.The opportunity to "set straight " those

children restricted because of loud functionalmurmurs previously considered organic, is anaspect of case-finding often overlooked.

SUMMARY

In an analysis for agreement of 3,272comparisons between listeners of tape-re-corded heart sounds, the degree of agreementwas about as good as that demonstrated bypairs of readers in miniature chest x-rays.This pilot study was accomplished withequipment considered inadequate and withlisteners of widely varied training.A specially built, automated tape-recording

unit has now been developed which makesscreening for heart disease in large numbersof individuals practicable.A technician can record approximately 250

children a day in the average Chicago publicschool. After a brief training period, thephysician-listener can screen 140 children inan hour, recalling those who require a

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physical examination. Field studies with thisequipment have shown that the number ofnormal children recalled is low and thatpractically no heart disease with abnormalheart sounds and murmurs is missed. It isthought that this technic offers a practicalway to screen large populations of childrenfor heart disease.

ACKNOWLEDGMENTThe authors wish to express their appreciation

for the valuable assistance and continuing interestof Mr. Louis deBoer, Executive Director of theChicago Heart Association, who gave the originalimpetus to this project. We also wish to thankDr. Arthur E. Rikli, Dr. John MeDonough, Mr.Philip Enterline, and Miss Gloria Labbe of theHeart Disease Control Section, U. S. PublicHealth Service, for their advice and statisticalhelp. Dr. Edward Press and Dr. Simon Rodbardalso aided us in the early stages of this project.

SUM MARIO IN INTERLINGUAIn un analyse del correlation de judica-

mento inter pares de auditores de 3.272phonomagnetogrammas de sonos cardiac, legrado de accordo esseva simile a illo demon-strate per pares de interpretas de microroent-genogrammas thoracic. Le hic-presentatestudio, de character preliminari, esseva execu-tate con equipamento considerate como in-adequate e con auditores de differentissimeexperientia.

IJn automatic apparato phonomagneto-graphic, specialmente construite pro le regis-tration de sonos cardiac, es nunc disponibile,permittente le execution de tests discrimina-tori pro morbo cardiac in grande numeros desubjectos.Un sol technico, usante le nove apparato,

es capace a obtener phonomagnetogrammascardiac ab approximativemente 250 juvenilesper die sub le conditiones de labor que estypicamente incontrate in le scholas publicde Chicago. Post un eurte periodo de traina-mento, le medico-auditor pote examinar leregistrationes de 140 juveniles in le cursode un hora, reclamante le subjectos pro quiun examine physic es indicate. Studios com-

parative, con le uso del nove apparatura suble conditiones del practica quotidian, hademonstrate que le numero del subjectos nor-mal reclamate es basse e que practicamentenulle easo de morbo cardiac con anormalitatedel sonos cardiac e con murumures cardiacescappa al detection. Es opinate que istetechnica representa un medio practic proeffectuar tests de discrimination pro morbocardiac in grande populationes juvenil.

REFERENCES

1. NADAS, A.: Pediatric Cardiology. Philadel-phia, W. B. Saunders Co., 1957.

2. KEITH, J., ROWE, R. D., AND VLAD, P.: HeartDisease in Infancy and Childhood. NewYork, W. B. MeMillan Co., 1958.

3. HOLT, L. E.: The problem of the cardiac childin New York City. Arch. Pediat. 34: 12,1917.

4. BAINTON, J. H.: Heart disease and school life.Am. J. Pub. Health 18: 1252, 1928.

5o. HALSEY, R. H.: Heart disease in children ofschool age. J.A.M.A. 77: 672, 1921.

6. COHN, A. E.: Heart disease from the point ofview of public health. Am. Heart J. 2:275, 1927.

7. Cardiac Survey of Children in the BostonSchools. The Nation's Health 9: 21, 1927.

8. CAHAN, J. M.: Incidence of heart disease inschool children. J.A.M.A. 92: 1576, 1929.

9. C LARK, T.: Heart disease, a public health prob-lem. Pub. Health Rep. 44: 2463, 1929.

10. HEWITT, E. S., AND GEDDIE, K. B.: Report ofphysical examination of high school stu-dents. Proc. Staff Meet., Mayo Clin. 6: 53,1931.

11. MEYERS, J.: Physical findings in New YorkCity continuation school boys; element invital statistics of adolescents. Am. J. Pub.Health 21: 615, 1931.

12. PAUL, J. R., HARRISON, E. R., SALINGER, R.,AND DEFOREST G. K.: Social incidence ofrheumatic heart disease; statistical study inNew Haven school children. Am. J. M. Se.188: 301, 1934.

13. CAHAN, J. M.: Rheumatic heart disease inPhiladelphia school children. Ann. Int. Med.10: 1752, 1937.

14. SAMPSON, J. J., CHRISTIE, A., AND GEIGER,J. C.: Incidence and type of heart diseasein San Francisco school children. Am. HeartJ. 15: 661, 1938.

15. RAUH, L. W.: The incidence of organic heart

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disease in school children. Am. Heart J. 18:705, 1939.

16. WEISS, M. M.: Incidence of heart disease inschool children of Louisville. Am. Heart J.22: 112, 1941.

17. WEDUM, E. G., WEDUM, A. B., AND BEAGHLER,A. L.: Prevalence of rheumatic heart dis-ease in Denver school children. Am. HeartJ. 22: 112, 1941.

18. JACKSoN, R.: Heart disease in a rural IowaCounty. J. Pediat. 29: 647, 1946.

19. ROBINSON, S. J., AGGELER, D. M., AND DAND-LOFF, G. T.: Heart disease in San Fran-cisco school children, 1947; Registry show-ing incidence, problems, and supervisiontechniques. J. Pediat. 33: 49, 1948.

20. RUSHMER, R. F., SPARKMAN, D. R., POLLEY,R. F. L., BRYAN, E. D., BRUCE, R. R.,WELCH, G. B., AND BRIDGES, W. C.: Vari-ability in detection and interpretation ofheart murmurs. A comparison of auseulta-tion and stethography. Am. J. Dis. Child.83: 740, 1952.

21. McKuSICK, V. A.: Cardiovascular Sound inHealth and Disease. Baltimore, The Wil-liams and Wilkins Company, 1958.

22. GECKELER, G. D., LIKOFF, W., AND MASON, D.:Teaching auscultation by endless loop taperecording. J.A.M.A. 152: 1335, 1953.

23. BUTTERWORTH, J. S., CHASSIN, M. R., ANDMCGRATH, R.: Cardiac Auscultation Includ-ing Audio-Visual Principles. New York,Grune & Stratton, Inc., 1955.

24. PAULIN, S., AND MANNHEIMER, E.: The physi-ological heart murmur in children. Actapaediat. 46: 438, 1958.

25. STILL, G. F.: Common Disorders and Diseasesof Children. London, Frowde, 1909, p. 434;Ed. 3, London, Oxford University Press,1918, p. 495.

26. LEATHAM, A.: Auscultation of the heart. Ped.Clin. North America, November, 1958.

27. WELLS, B.: The graphic configuration of in-nocent systolic murmurs. Brit. Heart J. 19:129, 1957.

28. MANNHEIMER, E.: Calibrated phonocardiog-raphy and electrocardiography. A clinico-statistical study of normal children andchildren with congenital heart disease.Acta paediat., Suppl. 2, 28: 1, 1940.

29. BUTTERWORTH, J. S.: Auditory and visualperception of cardiac vibrations. Circula-tion 15: 481, 1957.

30. YERUSHALMY, J., HARKNESS, J. T., COPE,J. H., AND KENNEDY, B. R.: The role ofdual reading in mass radiography. Am.Rev. Tubere. 61: 443, 1950.

9.CLINICAL EXPERIENCE

Others' follies teach us not,Nor much their wisdom teaches;

And most, of sterling worth, is whatOur own experience preaches.

-Tennyson: Will Waterproof's Lyrical Monologue.From C. SIDNEY BURWELL, M.D., and JAMES METCALFE, M.D. Heart Disease and Preg-nancy. Physiology and Management. Boston, Little, Brown and Company, 1958, p. 44.

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HAHNEMAN and JOEL WILLARDJACQUES M. SMITH, ROBERT A. MILLER, CARL MARIENFELD, BETTY

DiseaseUse of Tape-Recorded Heart Sounds in Screening of Children for Heart

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