ANATOMIC FACTORS CAUSING RESPIRATORY DISTRESS IN ACYANOTIC CONGENITAL CARDIAC DISEASE

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(Received November 15; accepted for publication December 16, 1968.)

This study was supported by Public Health Service Research Grant 5 ROl HE05694 and Research Training Grant 2 Ti HE05570 from the National Heart Institute.

ADDRESS: (J.E.E.) Pathology Department, Charles T. Miller Hospital, 125 West College Avenue, St. Paul, Minnesota 55102.

PEDIATRICS, Vol. 43, No. 5, May 1969

ARTICLES

ANATOMIC

FACTORS

CAUSING

RESPIRATORY

DISTRESS

IN ACYANOTIC

CONGENITAL

CARDIAC

DISEASE

Special

Reference

to

Bronchial

Obstruction

Paul Stanger, M.D., Russell V. Lucas, Jr., M.D., and Jesse E. Edwards, M.D.

From the Departments of Pediatrics and Pathology, University of Minnesota, Minneapolis, Minnesota and the Department of Pathology, The Charles T. Miller Hospital, St. Paul, Minnesota

ABSTRACT. Respiratory symptoms in acyanotic congenital cardiac disease may result from several factors, including cardiac failure and bronchial ob-struction. Significant bronchial compression by hy-pertensive pulmonary arteries and, in some cases, the left atrium, also may occur. Sites of predilec-tion are the left main bronchus and the left upper

and right middle bronchi. The latter two sites correlate with distribution of lobar emphysema in acyanotic congenital cardiac disease. Pediatrics,

47:760, 1969, RESPIRATORY DISTRESS, BRONCHIAL

OB-STRUCTION, ACYANOTIC CONGENITAL CARDIAC

DIS-EASE, LOBAR EMFHYSEMA, CONGENITAL HEART

DIS-EASE.

p

ULMONARY SYMPTOMS are common

among infants with acyanotic congeni-tal cardiac disease. In a given case, these

may represent a composite of effects,

in-cluding cardiac failure and bronchial

ob-struction with or without pulmonary

infec-tion.

From earlier reports of several authors,

compression of bronchi by hypertensive

pulmonary arteries has been described from

patients with left-to-right shunts.

Respiratory distress may result from

several factors, including (1) external

compression of bronchi, either by

pulmo-nary arteries or the left atrium, (2)

intralu-minal changes in bronchi, and (3)

compression of a lung by a massively

en-larged heart.

The purposes of this communication are

twofold, (1) to review the anatomic

fac-tors which cause mechanical interference

with respiration among patients with

acy-anotic congenital cardiac disease and (2)

to review the relationship of infantile lobar

emphysema with cardiac disease. Emphasis

will be made of the sites of bronchial

compression by hypertensive pulmonary

ar-teries.

EXTERNAL COMPRESSION OF BRONCHI

Hypertensive Pulmonary Arteries

Obstruction to the airways is most often

the result of bronchial compression by

adja-cent distended hypertensive pulmonary

ar-teries. The latter may be a manifestation

either of certain left-to-right shunts or of

pulmonary venous obstruction. A detailed

discussion of cardiac conditions associated

with pulmonary hypertension may be found

elsewhere. The anatomic relationships

be-tween the pulmonary arteries and the major

bronchi and their branches are such as to

make certain elements of the

tracheobron-chial tree particularly susceptible to

com-pression when the pulmonary arteries are

distended and tense (Fig. 1).’

The left side of the trachea, the proximal

part of the left main bronchus and the left

upper bronchus form a relatively inelastic,

C-shaped structure (Fig. 1 and 2a). The

space within this C-shaped structure

con-tains the left pulmonary artery and the

aorta. The aorta normally creates a slight

impression on the left side of the trachea.

When pulmonary hypertension is present,

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ARTICLES 761

against the left side of the trachea,

accen-tuating the tracheal indentation beyond

normal. This indentation is minor in

rela-tion to the caliber of the trachea and causes

no significant airway obstruction.

Neverthe-less, roentgen evidence of indentation of

the trachea by the aorta suggests

pulmo-nary hypertension.

The origin of the left pulmonary artery

lies anterior to the left main bronchus, then

crosses the superior aspect of the left main

bronchus obliquely to assume a posterior

position relative to this bronchus. The left

pulmonary artery then passes posteriorly to

the left upper lobe bronchus and beyond

that, descends into the lower lobe of the

left lung. \Vhen pulmonary arteries are

dis-tended, the foregoing anatomic

relation-ships account for two of the three sites in

the bronchial system which have a

predi-lection for compression. Most frequently

in-volved is the superior aspect of the left

main bronchus where the left pulmonary

artery crosses it (Fig. 1 and 2b). The

sec-ond site of bronchial compression is the

posterior aspect of the left upper bronchus

as the left pulmonary artery hooks around

it. The left pulmonary artery, as it ascends

to reach the left upper bronchus and then

descends behind it, may be considered an

arterial “staple” which tends to prevent the

left main bronchus from being displaced

upward (Fig. 3).

The third site of predilection for

bron-chial compression lies on the right side at

the junction of the intermediate and the

right middle bronchi. The primary division

of the right pulmonary artery lies anterior

to the right main bronchus (Fig. 4a). The

artery to the upper lobe of the right lung

ascends laterally along with, but inferiorly

to, the right upper bronchus. The arteries

to the right middle and lower lobes course

inferolaterally, pass anteriorly to the

in-termediate bronchus, then into a yoke

formed by the right upper bronchus above

and the intermediate and right middle

bronchi below. The artery to the lower lobe

crosses the superior aspect of the junction

of the intermediate and right middle lobe

bronchi. In patients with pulmonary

hyper-tension, a “hollowed out” compression is

frequently present at this junction (Fig. 1

and 4b). The right middle bronchus is most

often obstructed.

Left Atrial Enlargement

Bronchial compression caused by

hyper-tensive pulmonary arteries is intensified

when left atrial enlargement is also present.

Left atrial enlargement may have diverse

etiologies, i.e., mitral stenosis or

insuffi-ciency, left ventricular failure, left

ventric-ular outflow obstruction, and certain

left-to-right shunts, such as ventricular septal

defect or patent ductus arteriosus. The latter

shunts result both in pulmonary

hyperten-sion and left atrial enlargement, and

pa-tients with this combination are particularly

FIG. 1. Sites of predilection for compression of the tracheobronchial tree by distended pulmonary

ar-teries as viewed from the front. 1. The superior

aspect of the left bronchus (L. Br.) is compressed

as the left pulmonary artery crosses it. 2. The pos-terior aspect of the left upper bronchus (L. U.

Br.) is compressed as the artery to the left pul-monary artery hooks around it. 3. The artery to

the lower lobe of the right lung crosses the junc-tion of the intermediate bronchus (I. Br.) and the

right middle bronchus (R. M. Br.). Here the

bronchi are compressed. The distended left

pul-monary artery pushes the aorta (Ao.) medially and upward against the left lateral aspect of the trachea (T) and accentuates the normal

indenta-tion of the trachea by the aorta. The left recurrent laryngeal nerve which lies between the aorta and

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t

-,-,

FIG. 2. Compression of left bronchus and left upper bronchus b’ distended left atrium and left pulmonary artery in a 6-week-old infant with origin of both great vessels from the right ventricle with pulmonary hypertension. a.

Poste-rior view of trachea (T.), its bifurcation, and related structures. The left

main bronchus (L. Br.) is compressed as it is fixed by the left pulmonary

artery (L. P. A.) above and distorted by the enlarged left atrium (L. A.) from below. H. Br. = right bronchus. b. Left main bronchus (L. Br.) and its prunarv branches viewed laterally from a mediastinal position. The left bronchus has l)een transected and is seen on cross section. This structure is flattened and its lumen contains mucoid exudate. The left pulmonary artery has l)een removed to show the hollowed out deformities (between arrows) along the anterosuperior aspect of the left bronchus (L. Br.) and the posterior

portion of the left upper bronchus (L. U. Br.).

vulnerable to bronchial compression. The

left atrium lies immediately subjacent to

the tracheal bifurcation. An enlarged left

atrium presses upwar(l upon the inferior

as-pect of 1)0th major bronchi and tends to

in-crease the angle of the tracheal bifurcation.

The increase in the angle appears to result

mainly from upward deflection of the left

bronchus, while the right bronchus is rela-tively little affected. The tendency for the

left atrium to displace the left bronchus

up-ward is countered by the tendency of the

left pulmonary arterial “staple” to prevent

upward excursion of the bronchus. The ulti-mate effect is compression of the left main

stem bronchus as it lies between the left

FIG. 3. Diagram of compression of the tracheo-bronchial tree b’ the combination of distended pulmonary arteries and dilated left atrium. The left pulmonary artery ascends to reach the left upper bronchus (L. U. Br.), passes behind it, then de-scends into the lower lobe of the left lung. The above arterial segment may be considered an arte-rial “staple” (arrows) that compresses the left upper bronchus and prevents the left main bronchus from being displaced upward. The insert shows compression of the left bronchus between the sub-jacent dilated left atrium (L. A.) and the arterial

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R.PA.

I. Br.

atrium below and the left pulmonary artery

above (Fig. 3 insert and Fig. 5).

In patients with extrinsic bronchial

ob-struction secondary to enlargement of the

pulmonary arteries, the left atrium, or both,

extensive flattening and deformity are

read-ily apparent on cross sections of the

af-fected bronchi (Fig. 6).

The sequelae of bronchial obstruction

are dependent on its degree. Incomplete

obstruction may result in emphysema;

com-plete obstruction may result in atelectasis.

Atelectasis or emphysema usually involve

entire lobes. Both may exist in one lung. In

contrast, external compression of small

dis-tal bronchi is not readily apparent on

pathologic examination. Even obstruction

of a bronchus smaller than a lobar

bron-chus does not usually lead to atelectasis.’

This is explained by the protection offered

by intralobar collateral ventilation. Pores of

Kohn communicate between adjacent

al-veoli but no intraparenchymal

communica-tion exists between lobes.

INTRALUMINAL BRONCHIAL

OBSTRUCTION

Several factors contribute to intraluminal

bronchial narrowing. Infection results in

mucosal edema and excessive secretions.

Dehydration causes the secretions to be

more viscous. Engorgement of bronchial

vessels (as in pulmonary venous

obstruc-tion) results in excess secretions and

mu-cosal edema.

These intrinsic factors may result in a

critical decrease in intraluminal diameter at

the sites of extrinsic pressure or may be the

sole cause of airway obstruction (Fig. 7).

COMPRESSION OF LUNG BY A

MASSIVELY ENLARGED HEART

When the heart is grossly enlarged, the

left main bronchus may be obstructed and

this, in turn, may lead to atelectasis of the

entire left lung. A more common

complica-tion of gross cardiomegaly is atelectasis of

the lower lobe of the left lung (Fig. 8).

This localization occurs most frequently in

FIG. 4. Compression of the right middle and intermediate bronchi by a dis-tended pulmonary artery’ in a 3-month-old infant with a patent ductus arteriosus. a. Frontal view of right pulmonary artery (R. P. A.) and trachea

(T.). Beyond the right bronchus (R. Br.) and anterior to the intermediate bronchus, the right pulmonary artery divides into its niajor branches. The effects upon the related segments of the bronchial tree are shown in b. Same perspective as a but with the right pulmonary artery (R. P. A.) reflected up-ward and laterally. A hollowed out depression is present at the junction of

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‘I

FIG. 5. Posterior view of necropsv specimen from a 3-month-old infant with a ventricular septal de-fect and a patent ductus arteriosus. The left

bronchus (L. Br.) is compressed as it lies between the dilated left atrium (L. A.) and the left pul-monary artery (not in specimen). The angle of the tracheal bifurcation is widened to about 150#{176}, mainly the result of elevation of the left bronchus.

T. = trachea; R. Br. = right bronchus.

cases of endocardial fibroelastosis.8 It has

been described also in Pompe’s disease92

and in anomalous origin of the left coronary

artery from the pulmonary trunk (three of

the nine patients reported by Noren and

associates13). This complication appears to

be the result of direct compression of the

lung b’ the enlarged heart. The conformity

of the mediastinal surface of the left lung

to the shape of the massively enlarged

heart is evidence for parenchymal

compres-sion (Fig.9).

PREDILECTION OF THE INFANT TO

AIRWAY OBSTRUCTION

The peak incidence of respiratory

diffi-culties in acyanotic congenital cardiac

dis-ease occurs between the ages of 2 and 9

months. Spontaneous improvement, once

the patient is past this age, is not

uncom-mon. A brief discussion of the features

pe-culiar to infants is warranted.

The infant with a potential left-to-right

shunt is relatively free from clinical

svmp-toms during the neonatal period. The

mag-nitude of the left-to-right shunt is limited

by high pulmonary vascular resistance

pres-ent during the first few weeks. Although

the pulmonary arterial pressure is elevated

during this period, the pulmonary arteries

are small. As the peripheral pulmonary

‘as-cular resistance decreases, the magnitude of

the left-to-right shunt increases and

pulmo-nary arterial distention occurs. Congestive

cardiac failure and/or pulmonary

compli-cations make their appearance at this time

and are prominent during the remainder of

the first year of life. Spontaneous clinical

improvement in the latter part of the first

year corresponds temporally to several

ana-tomic changes. Some changes are intrinsic

to the cardiac defect and operate to reduce

the size of the left-to-right shunt either

ab-solutely or relatively; others are related to

structural changes within the pulmonary

system that render it less susceptible to

complications.

An example of intrinsic change of cardiac

nature is found in ventricular septal defect.

Recent studies have shown that

sponta-neous closure or reduction in size of even

large ventricular septal defects occurs

fre-quently during infancy.1 In other infants

with ventricular septal defect, an increase

in pulmonary vascular resistance results in

diminished pulmonary blood flow and a

de-crease in left atrial size. In both of these

circumstances, spontaneous improvement in

the underlying hemodynamic problem is

as-sociated with a decrease in pulmonary

com-plications.

Anatomic changes within the

broncho-pulmonary system may also serve to

de-crease pulmonary complications as the

pa-tient grows older. Since resistance to flow

of air through bronchial lumina is

in-versely proportional to r4 (r = radius of

the lumen), relatively slight degrees of

com-pression or intraluminal narrowing of the

small bronchi of young infants result in

bronchial obstruction. With growth, the

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I:

FIG. 6. Photomicrographs of the right (a) and left (b) bronchi from the pa-tient shown in Figure 5. The right bronchus is virtually circular while the left bronchus has been flattened in its superior-inferior dimension. Knowledge

that compression deformities of the tracheobronchial tree remain long after the cause of the compression is removed is derived from the experience that

patients with tracheal compression by a vascular ring may continue to have symptoms months after the surgical correction of the underlying cause.

H and E.

airways are less readily obstructed. The

soft, pliable bronchial cartilage of infants is

0 I

I

FIG. 8. Pulmonary atelectasis in a 6-month-old infant with endocardial fibroelastosis. a. Thoracic roentgen-ogram. The lower lobe of the left lung (lateral border along arrows) is collapsed. b. Postmortem bronchogram showing obstruction of the left bronchus. Obstruction is not complete as evidenced by the emphysematous upper lobe of the left lung. The contrast material was probably too viscid to pass through

the narrowed left bronchus.

for lobar emphysema is identified in

ap-proximately one half of cases; no cause is

found in the remainder. A variety of

condi-tions may be identified as causing bronchial

compression which, in turn, is responsible

for infantile lobar emphysema. These

in-clude deficiency of bronchial cartilage,

bronchial stenosis, redundant bronchial

mu-cosa, compression by aberrant vessels,

FIG. 9. Compression of the lung by a massively enlarged heart. Posterior view of lungs and bronchi from a 22-month-old child with endocardial fibro-elastosis. There is marked atelectasis of the lower lobe of the left lung (L. L. L.). The mediastinal surface of the left lung conforms to the contour of

the heart, which was massively’ enlarged.

compression by lymph nodes, or kinking of

the bronchus of a herniated lobe in the

ab-sence of a mediastinum. Several recent

re-ports have stressed the association of

con-genital cardiac disease and infantile lobar

emphysema. Only Pontius21 has considered

that dilated pulmonary arteries in patients

with congenital cardiac disease might cause

bronchial obstruction of sufficient degree so

as to give rise to lobar emphysema. Cottom

and Myers22 recognized this possibility but

chose to regard infantile lobar emphysema

as an anomaly separate from any associated

cardiac anomalies.

We reviewed 138 cases of infantile lobar

emphysema from the literature. 2o2S

Exclu-sive of two cases with aberrant left

pul-monary artery arising from the right

pul-monary artery, there were 26 cases with

congenital cardiac disease.213,2l27 In

addi-tion to the cases in the literature, we have

observed infantile lobar emphysema in two

patients, one with a ventricular septal

de-fect and the other with patent ductus

arte-riosus (Fig. 10). The types of cardiac

dis-ease associated with lobar emphysema are

listed in Table I.

Among these 28 patients with infantile

lobar emphysema and congenital cardiac

disease, 21 had left-to-right shunts

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ar-TABLE I

INFANTILE LOBAR EMPHYSEMA ASSOCIATED WITH

CONGENITAL CARDIAC DISEASE

Type of Congenital Cardiac Disease (Na mber of (‘a.ses)

Number

of Cases Reference

Without pulmonary hypertension or dilated pulmonary arteries

(3cases)

VSD and pulmonary stenosis pulmonary stenosis tetralogy of F’ullot

I l

I 3.l4

* One case each in present series. \‘SD = ventricular septal defect. PDA patent ductus arteriosiis.

ARTICLES 767

teriosus

)

.

While hemodynamic data are

available from these cases, it seems fair to

assume that pulmonary hypertension was a

common phenomenon. In the remaining

seven cases, there was one example of

pul-monary stenosis and six of the tetralogy of

Fallot. In two of the patients with the

te-tralogy of Fallot, the pulmonic valve was

absent and gross dilatation of the

pulmo-nary arteries was present. In two other

cases with the tetralogy, there were

markedly dilated pulmonary arteries. In our

analysis, these four cases of tetralogy of

Fallot with distended pulmonary arteries

have been grouped with cases exhibiting a

left-to-right shunt. The findings in the latter

four cases suggest the presence of acyanotic

tetralogy. The remaining two examp1es of

tetralogy and the one case of pulmonary

stenosis have been considered separately.

Among cases with lobar emphysema

when the pulmonary arteries were dilated

(as judged by underlying anomaly or by

di-rect visualization), the middle lobe of the

right lung and the upper lobe of the left

lung were most often affected (Fig. 11). In

four cases the entire left lung was involved.

This distribution is similar to the sites of

predilection for bronchial compression by

distended pulmonary arteries. Infantile

lobar emphysema in patients with

congeni-tal cardiac disease may represent the most

dramatic sequela of bronchial compression

by distended pulmonary arteries.

A similar but less marked predilection for

the middle lobe of the right lung, the upper

lobe or both lobes of the left lung is also

present in cases of infantile lobar

em-physema not associated with a cardiac

anomaly (Fig. 1 lc).

COMMENT

This report emphasizes that distended

pulmonary arteries have predilection for

causing external compression of certain

seg-ments of the bronchial tree. Obstruction of

the airway so caused may serve to favor

in-fection. This factor, in turn, may result in

an increase in amount of bronchial

secre-tion. The latter factor may be a unit in a

vi-FIG. 10. Infantile lobar eniphysema associated with patent ductus arteriosus. Thoracic roentgenogram in a 3-month-old infant with progressive respira-tory difficulty since birth. The emphysematous upper lobe of the lung is radiolucent and herniates into the right hemithorax. The mediastinum and the heart are shifted to the right. A left upper lobectomy was performed, but the patient expired in the immediate postoperative period. Necropsy showed the presence of a 3 mm wide, patent

due-tus arteriosus.

cious cycle which favors not only atelectasis but also continuation of infection.

It is known from experience with

vascii-lar rings that the deformity of the

tracheo-With pulmonary hypertension or dilated pulmonary arteries

(5 cases)

VSD 11 I-I3.

PDA’ 7 1-5

VSD and PDA I

PDA and coarctation of aorta I. 5

tetralogy ofFallot 6

tetralogy with absent pulmonary

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a. b. c.

FIG. 11. Distribution of lobes involved in cases of infantile lobar emphysema

as determined from available literature. Numbers refer to number of cases observed. Density of shading tends to emphasize relative frequency of in-volvement. a. Congenital cardiac disease commonly associated with dis-tended pulmonary vessels. b. Congenital cardiac disease not usually

associ-ated with distended pulmonary vessels. c. Without congenital cardiac disease or no mention of congenital cardiac disease.

bronchial tree caused by anomalous arteries

may remain for some time after the cause

of the deformity is removed. A similar

situ-ation may apply when bronchi are

com-pressed and deformed in cardiac disease.

Then the patient in whom the underlying

cardiac disease is corrected may continue to

exhibit bronchial deformity for some time.

This is probably one of the factors

responsi-ble for respiratory complications following

cardiac surgical procedures done on infants.

SPECULATION

Respiratory complications are significant

factors limiting successful management of

the infant with congenital cardiac disease.

The cardiac basis for many of these

pulmo-nary problems represents a new dimension

to be considered in planning treatment.

One must consider the possibility that

known postsurgical respiratory

complica-tions may be of lesser consequence than the

respiratory complications associated with

the underlying cardiac disease.

The occurrence of lobar emphysema in

infants with cardiac disease and the

similar-ity of the affected lobes in “idiopathic lobar

emphysema” suggests that cardiac disease

may be an important etiologic factor in this

entity. When lobar emphysema is related to

cardiac disease, an unsolved problem is

whether primary treatment should be

di-rected toward the cause (cardiac disease)

or to the symptom (lobar emphysema).

SUMMARY

The anatomic features of acyanotic

con-genital cardiac disease which cause

pul-monary atelectasis and emphysema are

iden-tified. Extrinsic airway obstruction most

frequently results from compression of

bron-chi by distended pulmonary arteries and/or

by an enlarged left atrium. The sites of

pre-dilection are the left upper bronchus, the left

main bronchus, and the right middle

bron-chus. Intraluminal airway obstruction

re-suits from mucosal edema and from

exces-sive secretion. Atelectasis of the left lower

lobe is commonly associated with massive

cardiomegaly and is probably the result of

direct compression of pulmonary

paren-chyma.

Infantile lobar emphysema is associated

with acyanotic congenital cardiac disease

and may represent another sequela of

bron-chial compression by distended pulmonary

arteries and enlarged left atrium.

REFERENCES

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2. Krabbenhoft, K. L., and Evans, \V. A., Jr.:

Some pulmonary changes associated with in-tracardiac septal defects in infancy. Radiol-ogy, 63:498, 1954.

3. Bryk, D.: Atelectasis, emphysema, and heart diseases. A pattern of left lung disease in in-fants associated with left-to-right shunt. Amer. J. Dis. Child., 110:100, 1965.

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and Varco, R. L.: Massive atelectasis of the left lung in children with congenital heart disease. J. Thorac. Cardiov. Surg., 34:116, 1957.

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8. Davis, L. A.: Pediatric Radiology. Baltimore: Williams and Wilkins Co., pp. 15.29 and 15.33, 1961.

9. DiSant’Agnese, P. A., Andersen, D. H., and

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the heart. II. Critical review of the litera-ture. PEDIATRICS, 6:607, 1950.

10. Dincsoy, M. Y., Dincsoy, H. P., Kessler, A. D., Jackson, M. A., and Sidbury, J. B., Jr.: Gen-eralized glycogenosis and associated endo-cardial fibroelastosis. Report of 3 cases with biochemical studies. J. Pediat. 67:728, 1965. 11. Coyer, R. A., and Bowden, D. H.: Endocardial

fibroelastosis associated with glycogen tu-mors of the heart and tuberose sclerosis. Amer. Heart J., 64:539, 1962.

12. Nadas, A. S.: Pediatric Cardiology, ed. 2. Phil-adelphia: W. B. Saunders Co., p. 260, 1964. 13. Noren, C. R., Raghib, C., Moller, J. H.,

Am-platz, K., Adams, P., Jr., and Edwards, J. E.: Anomalous origin of the left coronary ar-tery from the pulmonary trunk with special reference to the occurrence of mitral insuffi-ciency. Circulation, 30:171, 1964.

14. Lucas, R. V., Jr., Adams, P., Jr., Anderson, R. C., Meyne, N. C., Lillehei, C. W., and Varco, R. L.: The natural history of isolated ventricular septal defect. A serial physiologic study. Circulation, 24:1372, 1961.

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Spontaneous closure of ventricular septal

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16. Lynfleld, J., Casul, B. M., Arcilla, R., and Luan, L. L.: The natural history of ventricu-lar septal defects in infancy and childhood. Based on serial cardiac catheterization stud-ies. Amer. J. Med., 30:357, 1961.

17. Hoffman, J. I. E., and Rudolph, A. M.: The

natural history of ventricular septal defects in infancy. Amer. J. Cardiol., 16:634, 1965. 18. Simmons, R. L., Moller, J. H., and Edwards,

J. E.: Anatomic evidence for spontaneous closure of ventricular septal defect. Circula-tion, 34:38, 1966.

19. Spencer, H. S.: Pathology of the Lung. New York: Macmillan, p. 410, 1962.

20. Leape, L. L., and Longino, L. A.: Infantile lobar emphysema. PEDIATRICS, 34:246, 1964. 21. Pontius, R. C.: Bronchial obstruction of con-genital origin. Amer. J. Surg., 106:8, 1963. 22. Cottom, D. C., and Myers, N. A.: Congenital

lobar emphysema. Brit. Med. J., 1:1394, 1957.

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Meyer, B. W., and Patrick, J. R.: Lobar

emphysema and congenital heart disease

in infancy. J. Thorac. Cardiov. Surg., 49:1, 1965.

24. Jones, J. C.: Personal communication.

25. Staple, T. W., Hudson, H. W., Hartmann, A. F., Jr., and McAlister, W. H.: The angio-graphic findings in four cases of infantile

lobar emphysema. Amer. J. Roentgenol.,

97:195, 1966.

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lobar emphysema: Long-term effects and

sequelae in related cases. Surgery, 59:601, 1966.

28. Kamphuys, E. H. M.: Congenital lobar

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1969;43;760

Pediatrics

Paul Stanger, Russell V. Lucas, Jr. and Jesse E. Edwards

CONGENITAL CARDIAC DISEASE: Special Reference to Bronchial Obstruction