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Hypoplasia of the pulmonary arteries
Brit. J. Dis. Chest (1959) 53~ 253.
HYPOPLASIA OF THE PULMONARY ARTERIES BY j . R. BELCHER, L. CAPEL, J. N. PATTINSON AND J. SMART From the London Chest Hospital, London, E.2 THE term " unilateral emphysema " has been used to describe a group of cases which presents with increased radiolucency of part or the whole of one lung. Although emphysema is usually a generalised disease, it may be confined to one segment of the lung. When this is the case, that segment occupies more space than normal and this can readily be recognised on a radiograph. Emphysema is, however, but one of a variety of pathological processes which may produce increased radiolucency. This appearance is due to a decrease in the size and number of the pulmonary blood vessels in the area. It may be seen in bronchiectasis, or in bronchogenic carcinoma, due to spreading out of the vessels secondary to compensatory expansion in a lobe adjacent to the collapsed segment. Less frequently, areas of increased radiolucency may occur in a bronchiectatic lobe itself. When partial bronchial obstruction is present overdistension of the lobe distal to the block gives rise to increased radiolucency accompanied by displacement of adjacent structures. Diminished vascularity may also be caused by thrombosis of a pulmonary artery (Shapiro and Rigler, 1948 ) or by neoplastic occlusion of the artery. There is another group of cases, forming the subject of this paper, in which the pulmonary artery in the affected segment is hypoplastic. The characteristic radiological features are: I. The whole of one pulmonary artery, or of one of its lobar branches, is diminished in size. The segmental arteries are also reduced in size and in number. 2. Increased radiolucency of one lung or of one or two of its lobes is evident, owing to this decrease in vascularity. 3. The affected area of lung is decreased in size. Since the publication of 3 cases of hypoplasia of a lobar pulmonary artery in 195 7 we have collected a further 9 examples, and also 4 additional cases in which the whole o f the pulmonary artery on one side was affected. CLINICAL PRESENTATION The details of the presentation of these 13 new cases is given in Table I. Only one was a w o m a n and this dominant male incidence was also seen in other published series (Table II). The average age of the patients was 45 years, with extremes of 18 and 58 . The condition was discovered either at routine X-ray or following the development of the variety of symptoms for which (Receivedfor publication February 28, x959.)
BELCHER~ CAPEL~ PATTINSON AND SMART
254
TABLE I.--SUMMARY OF THE HISTORY AND FINDINGS IN THE 13 PATIENTS
Case Age Sex No. iyrs.
Site
Anglo
I
58
M.
R.L.Z.
+
2 3
49 42
M. M.
L.L.Z. R.L.Z.
+ +
4
39
M.
R.L.Z.
+
5
54
M. R.L.Z.
+
6
28
M.
L.L.Z.
+
7
46
M. R.L.Z.
+
8
45
M.
R.L.Z.
+
9
49
M.
R.L.Z.
+
IO
49
M. !L. lung
+
II
55
M.
L. lung
+
I2 I3
4I 32
F. M.
R. lung L. lung
O O
I
Effort Childhood disability illness
Bronchogram
Peripheral Mild o "blobs" Normal o o No dilatation o at 2 yrs. Slight crowding A few "blobs" Moderate o peripherally Mod. tubular Severe o dilatation Mild tubular o at I yr. dilatation Normal o o No dilatation o o Slight crowding One large "blob" Mild o Spidery bronchi Spidery bronchi Moderate at 8 yrs. Moderate tubular Moderate at 8 yrs. dilatation in L. lower lobe only O o o o o O
History 5 weeks cough. Chest pain. Productive cough. 2o years increasing bronchitis. 20 years increasing bronchitis. Cough and haemoptysis. Cough and haemoptysis. I o years cough. Cough and dyspncea. Progressive dyspnoea. Increasing bronchitis. No symptoms. No symptoms.
TABLE II.--SUMMARY OF CASES PREVIOUSLY REPORTED
Author Swyer and James .. Dornhorst et al.
..
Age
Sex
Site
Comments
6
M.
lZ. lung
Three attacks of pneumonia.
17
M.
L. lung
Dyspnoea. Pneumonia at. 7 and
35 ? ?
M. M. F.
R. lung R.U.L. L. lung
Dyspnoea. Cough and sputum. Mass X-ray.
41
F.
L. lung
25 32 34 4° 32 35 I8 I8
F°
M. M. M. M. M. M. M.
L. R. R. L. L. R. L, L.
Progressive dyspnoea and bronchitis. Cough. Cough and haemoptysis. Dyspnoea. Cough and dyspnoea. Cough, dyspnoea and wheeze. Dyspnoea and bronchitis. Mass X-ray. Mass X-ray.
II.
Macleod
....
lung lung lung lung lung lung lung lung
HYPOPLASIA OF THE PULMONARY ARTERIES
255
patients are referred to a chest clinic (Table III). There was no characteristic history, but on direct questioning 4 patients recalled a " severe chest infection " during childhood or adolescence. TABLE III.--SUMMARY OF THE CLINICAL PRESENTATION IN THE 13 PATIENTS
One lobe affected History of chest in childhood Dyspnoea " Bronchitis " Hmmoptysis No symptoms
infection . . . . .....
One lung affected
2
4
. . . .
io 2 o
. . . . . . . .
SITE
O f the 9 cases in which a lobar artery was affected, 7 were on the right side and the lower lobe trunk was involved in all. In the 4 in which the whole pulmonary artery on one side was affected, one was on the right and 3 were on the left. RADIOLOGICAL
APPEARANCES
Increased radiolucency was present in about half of the lung in 9 cases (Fig. i)* and throughout the whole lung in 4 (Fig. 2). The pulmonary artery in the affected lung or lobe was decreased in size at its root. Its branches were reduced both in number and in size. When the whole pulmonary artery on one side was involved, the contralateral artery and its branches were enlarged (Fig. 2). The lung or lobe affected was reduced in size, as shown by the elevation of the dome of the diaphragm, displacement of the mediastinum towards the affected side, and by the position of the interlobar fissures. The diminished size of the pulmonary artery was evident on a plain P.A. radiograph, but tomography was useful in confirming this. On fluoroscopy of the patients with the whole of one lung affected, the mediastinum was seen to swing away from the lesion during forced expiration. This was accompanied by an unusual increase in density of the vascular markings in the good lung. During forced inspiration, the mediastinum appeared to swing towards the lesion: this might have been merely the return of the mediastinum to its normal position after the preceding expiration. These changes in the position of the mediastinum were noted by Macleod (i954). When only a lobe was involved, it was more difficult to detect trapping, as this would have been masked by the normal lobe. Local air trapping may also be masked when there is generalised chronic bronchitis and emphysema. BRONCHOORAPHY
This was carried out on both sides in i I cases, the only exceptions being 2 patients in whom the whole of the fight lung was affected. In the majority * T h e f i g u r e n u m b e r s i n t h e t e x t re fe r t o P l a t e s X K X V I I I - X X X l K .
256
BELCHER, CAPI~L~ PATTINSON AND SMART
the bronchogram was abnormal, but this abnormality in most was not typical bronchiectasis. In one case the bronchi in the affected right lower lobe and in the rest of the right lung were entirely normal. In the left lower lobe, where the arterial pattern was normal, there was mild dilatation of the peripheral parts of the basal bronchi. In another the bronchogram on both sides was normal. Minor to moderate tubular dilatation of lobar and segmental bronchi with poor filling of their smaller branches was observed in only 2 cases. M i n i m a l dilatation of the periphery of the basal bronchi only was seen in one additional case. Bronchial abnormalities of an unusual character were seen in 4 patients, consisting of small rounded areas in which pooling of contrast medium occurred. These " blobs " arose from the 4th to 6th order bronchi and were not confined to the radiolucent segment but were scattered throughout the lung (Fig. 3). T h e " blobs " v a r i e d in n u m b e r and size and in one case only one l a r g e " blob " was present. Crowding of lobar bronchi with very poor filling of their segmental branches, but without bronchial dilatation, was seen in 2 patients. In one case the only abnormality was a generalised reduction in the calibre of the bronchi, which had a " spidery " appearance. This feature was also seen in 2 of the cases described above in which " blobs " arose from minor bronchi. ANGIOGRAPHY
Little has been published on the normal size of the pulmonary arteries and their branches. I n order to interpret the angiographic findings in our series of cases, measurements were made of the pul m onary arteries and their branches in a group of 52 patients who had had angiocardiograms and in w hom there was no reason to believe that the size of the pul m onary vessels was affected by TABLE IV.--MEASUREMENTS OF THE DIAMETER (IN MM.) OF THE PULMONARY ARTERIES T h e s e w e r e o b t a i n e d f r o m t h e a n g i o c a r d i o g r a m s o f 5 2 p a t i e n t s in w h o m t h e r e w a s n o r e a s o n to e x p e c t t h a t t h e p u l m o n a r y arteries w e r e a b n o r m a l .
P.T. R.P.A. R.U.L. R.L.L. )) R.L.L.(2) L.P.A. L.U.L. L.L.L.(,) L.L.L.(2) I
Number of cases Maximum diameter Minimum diameter Mean diameter
51
52
5°
52
50
48
32
47
47
4I
32
i8
25
I6
33
I4
24
I5
I2 i9.i
Io i~.76
I8 6 24"77 xo.4
I2 I7.72
I I "2~
I8 22 30"77 24.6
7 12"2 5
7
disease. T h e points at which the arteries were measured on the angiograms are shown on Fig. 4 and the findings are recorded in Table IV. Measurements of the pulmonary arteries were also taken in 12 post-mortem specimens (Table V). It can be seen that there is a close correlation between the angiographic and post-mortem measurements of the pul m onary arteries in normal lungs.
PLATE X X X V I I I
FIG. I . - - A radiograph showing increased radiolucency of the right lower lobe and a small lobar artery.
Fro. 2 . ~ A radiograph showing increased radiolucency of the whole left lung. The left pulmonary artery is small and the right one large. (Film taken in expiration.)
~
/~-,a
v ~z_~~_
VLLL,,
l~Io"3.--Case I. A bronchogram showing scattered spherical dilatations o f the peripheral bronchi throughout the whole right lung.
FIG. 4 . - - A diagram to show the points at which the measurements of the pulmonary arteries were made.
To face p.
o56
PLATE XXXIX
FIG. 5.--Case 7- An angiogram showing hypoplasia of the right lower lobe artery (6 ram.).
FIG. 6.--Case i i. An angiogram showing hypoplasia of the left pulmonary artery (I 4 mm. diameter), and a large right pulmonary artery (3 6 mm. diameter).
FIG. 7.--Case I I. A radiograph in inspiration in a case with a small left pulmonary artery.
FIG. 8.--Case I I. A radiograph in expiration showing " trapping ".
257
HYPOPLASIA OF THE PULMONARY ARTERIES
Allowances should be made for slight shrinkage after death and for a radiographic magnification of about 13 per cent. Since the external diameter of the arteries was measured at post-mortem and the internal diameter on the angiocardiogram films, the correction factors tend to cancel one another out. Angiography accurately depicts pulmonary artery size, for stream effects from inadequate mixing of contrast medium and blood do not occur with the intravenous or right atrial injection used in this series. Angiograms were also done in 3 patients before operation for bronchiectasis. The lobar artery in the affected area was reduced in size on the angiogram, and here again the measurements corresponded closely with those on the specimen. TABLE V.--PuLMONARY ARTERY DIAMETERS
Post-mortem number
37 I 372 373 376 377 380 386 388 39° 392 378 379
P.T. L.P.A. R.P.A.
Pulmonarytrunk ext. diam. (mm.)
Right pul. artery ext. diam. (mm.)
Left pul. artery ext. diam. (mm.)
37 32 3o 28 29 3° 27 3I 32 34 28 35
25
27
20 20 20 21
22 20
Max.
Min.
37 ram. 27 mm. 26 mm.
27 ram. 18 mm. 19 mm.
24 19 23 2x
26 21 26
22
19 22 x8 25 20 25 18 22
Mean
31 ram. 22"5 mm. 22.2 mm.
Angiograms in several cases of emphysema were studied. The right and left pulmonary arteries were enlarged whilst their lobar branches gradually tapered down in size from their origins, which were more or less normal in diameter. The major abnormality was seen in the segmental and more peripheral arteries, which were much reduced in size and number. Angiograms Were obtained in x I of our cases with hypoplasia of the pulmonary arteries, and measurements of the diameter of the pulmonary vessels taken at the points indicated in Fig. 4 are shown in Table VI. The affected artery was greatly reduced in size at its origin (Figs. 5 and 6) and its branches were reduced in size and number. In the affected area the circulation rate was invariably sIower than normal, often markedly so. This phenomenon is also seen in emphysema and bronchiectasis. VOL. LIII. 3
4
258
BELCHER, CAPEL, PATTINSON AND SMART TABLE VI.--DIAMETER OF THE HYPOPLASTIC PULMONARY ARTERIES COMPARED WITH THE CORRESPONDING ARTERY ON THE OPPOSITE SIDE. MEASUREMENTS OBTAINED FROM ANGIOORAMS AND GIVEN IN MM.
Case number
Arteryto R.L.L.(e)
Artery to L.L.L.(e)
5
14
I2
6
6 9 6
IO 2o
3tO
I5 7 I4 I5
5
II
Right pulmonary artery
pulmonary artery
I3 6
IO II
I2
I3
Left 2O
34 36 No angiogram No angiogram
z4
Average diameter of the nine hypoplastic lobar arteries = 6"7 mm. Average diameter of the corresponding contralateral arteries = 13-8 mm. LuNG
FUNCTION
STUDIES
O f the 9 patients with one lobe only involved, 5 were investigated by spirometry and bronchospirometry and 4 by fluoroscopy. O f the 4 patients with the whole of one lung involved, all were investigated by spirometry and fluoroscopy, and the 2 patients who later underwent pneumonectomy were also investigated by bronchospirometry. After operation their simple spirometry was repeated. The results are shown in Table VII. The essential functional defect was a great reduction in oxygen uptake with marked, moderate or slight reduction in the tidal volume of the affected area when compared with the rest of the lung. These changes are also seen in bronchiectasis. These defects were revealed by bronchospirometry. In the 2 cases in which the whole of one lung was involved, and where therefore there was no contribution from a normal lobe to mask the defect, oxygen uptake was about 5 per cent. of the total, while the tidal volume was 13 per cent. and 23 per cent. of the total. Where only one lobe was affected, similar defects were present but partly masked by the contribution of the unaffected part of that lung. Tidal volume was reduced in all. PATHOLOGY
Four specimens in all are available for histological study, 2 from this series and 2 from the series reported in 1957. The findings will be "reported in detail by Dr. Lynne Reid in a separate publication.
14YPOPLASIA OF T H E P U L M O N A R Y ARTERIES
259
TABLE VII.--LuNG FUNCTION STUDIES
Bronchospirometry Lung zone ~umber affected I 2
3 4 5 6 7 8
9 IO II I2
13
R:L.Z. L.L.Z. R.L.Z. R.L.Z. R.L.Z. L.L.Z. R.L.Z. R.L.Z. R.L.Z. L. lung Post-opm L. lung Post-opn. R. lung L. lung
Trapping on fluoroscopy
Oxygen uptake %
Tidal
F.E. V
F.E.R.
V.C. %
Trap.
R . 22~o
R. 37%
+
lO5O
50
R. 39%
L. 40%
R. R. R. L.
o o +++ +
151o lO6O 580 2760
52 50 45 61
++ +++
L. 32%
+
+++
L. 5%
L. 26%
++ +
lO3O I24O 123°
6o
L. o t o IO
++ ++
++ +++
volume %
R. 3o% R.
5%
46% 35% 20% 5I%
IOOO IOOO
16oo
m
19oo
63 61 5° 5° 67 61
TheForcedExpiratoryRatio(F.E.R. = one second forced expiratory volume as a percentage of forced vital capacity) is above 7° per cent in healthy people. When the F.E.R. is below 60 per cent., obstructive airway disease is usually present, and as its severity increases the F.E.R. drops towards 30 per cent (Capel and Smart, 1958). At bronchospirometry the tidal volume, oxygen uptake and vital capacity of the right lung is usually found to be 55 per cent. of the total in health. Discussion
T h e 13 cases described here h a d certain radiological features in c o m m o n : increased r a d i o l u c e n c y of the whole or p a r t o f one lung, decrease in size o f the affected segment a n d great r e d u c t i o n in size Of the p u l m o n a r y arteries. T h e y resemble the cases described b y M a c l e o d (I954) , who c o m m e n t e d on the paucity of vascular markings in his series. A n g i o g r a p h y , done in I I o f o u r 13 cases, showed a great reduction in the size a n d n u m b e r o f the p u l m o n a r y arteries and a diminished circulation rate in the affected area. T h e angiographic appearances differed f r o m those seen in e m p h y s e m a in t h a t the affected p u l m o n a r y a r t e r y was small at its origin. I n e m p h y s e m a the p u l m o n a r y a r t e r y is often enlarged up to the origin of its lobar branches. T h e lobar arteries are more or less n o r m a l in d i a m e t e r at their c o m m e n c e m e n t a n d gradually t a p e r off peripherally. T h e e m p h y s e m a t o u s lobe or lung is also increased in size. T h e small size o f the p u l m o n a r y a r t e r y is not a s e c o n d a r y change due to bronchiectasis, for the b r o n c h o g r a m was n o r m a l in 2 o f o u r cases and bronchial dilatation was absent in a n o t h e r 2. T h e p u l m o n a r y a r t e r y supplying a grossly diseased lung u n d o u b t e d l y becomes r e d u c e d in size, b u t seldom below 60 per cent. o f its n o r m a l d i a m e t e r (Bj6rk a n d Saldn, 1950). I n our series o f h y p o p l a s t i c arteries the average d i a m e t e r of the affected lobar arteries at their origin was 6" 7 ram. while the corresponding contralateral vessels averaged i3.8 m m .
260
BELCHER, CAP]EL~ PATTINSON AND SMART
(Table VI). Such a prominent reduction in size (over 5 ° per cent.) is seldom seen even in severe bronchiectasis. A diminution in the size and number of the peripheral pulmonary arteries is seen in primary and secondary pulmonary hypertension. These changes, however, are bilateral and the reduction in calibre occurs distal to the second subdivision of the artery. The main pulmonary arteries and their lobar branches are enlarged (Goodwin, Steiner and Lowe, i952 ). Similar changes may be produced by multiple peripheral emboli or thromboses. The anglographic appearances in these conditions are quite different from those seen in our cases. We suggested in a previous paper (Belcher and Pattinson, I956 ) that a congenital origin was the most likely cause of the arterial hypop!asia and that infection and bonchiectasis might be complicating factors. Since congenital absence of the pulmonary artery to one lung may occur (Madoff and others, i952; Emanuel and Pattinson, I956), it is probable that congenitally small arteries also exist. When one pulmonary artery is congenitally absent, the affected lung is small. Diminished size of that portion of the lung supplied by the hypoplastic artery was a constant feature in our cases. A congenital defect in the form of abnormal interlobar fissures was seen in 2 of our previously reported cases. In our cases in which the whole of the pulmonary artery on one side was small, the contralateral artery was enlarged (Fig. 6), suggesting that the hypoplasia was at least of long-standing. Such enlargement is seldom seen even m a n y years after pulmonary resection in children, and even then not to a marked degree. Smart and Pattinson (1956) reported a case of congenital absence of the left pulmonary artery. Oxygen uptake by the left lung was nil, while the tidal volume was only slightly reduced. Similar results were obtained in 3 other unpublished cases. Therefore complete absence of a pulmonary artery will not of itself necessarily cause a ventilatory defect. In one patient previously reported (Case 3 in I957) there was a marked loss of oxygen uptake in the presence of a normal tidal volume. In such cases the lesion may be solely congenital in origin. When both ventilation and oxygen uptake are defective, the lesion may be due to an acquired ventilatory defect complicating a congenital arterial anomaly, but the possibility that the lesion is entirely acquired cannot be excluded. The abnormality in some cases might be due to lung damage suffered during the growing period. This possibility is favoured by the relative frequency with which serious chest illness in childhood has been reported in this condition (Table VIII). The strongest argument against a congenital mtiology is that the condition has never been reported in infancy. Hypoplasia of the artery, however, is not in itself responsible for symptoms, and the abnormality may easily be overlooked on a chest radiograph. In several of our cases the appearances on previous radiographs had been ignored or misinterpreted. It is also very probable that the small size of the arteries will be missed at routine post-mortem, particularly when lobar arteries alone are involved. Symptoms due to secondary or unrelated pulmonary disease frequently
26I
IIYpoPLASIA OF THE PULMONARY ARTERIES
appear for the first time in men between the ages of 4 ° and 5° years. As a result, most of our patients and those in other reported series were men in their early forties who presented with a variety of chest complaints (Table III). Although the abnormal lobe or lung in itself causes no symptoms, the respiratory reserve is diminished, for the affected area takes up little oxygen (Table VII). Thus the respiratory effort required to fill the useless part of the lung is wasted. If then the respiratory reserve in the rest of the lungs becomes reduced from whatever cause (such as chronic bronchitis), the presence of the abnormality will contribute indirectly to the breathlessness. It will do so not only because of the loss of respiratory reserve, but also because in some cases it may diminish the ventilation of the other lung. It may do this if air trapping during exercise causes a mediastinal shift towards the normal lung (Figs. 7 and 8). Trapping was present in each of the 4 patients with the whole of the right or left pulmonary TABLE V I I I . - - I N C I D E N C E OF SEVERE ILLNESS IN CHILDHOOD IN 43 PATIENTS WITH UNILATERAL HYPOPLASIA OF A PULMONARY ARTERY, OF WHOM 06 WErE QUESTIONED, .AND IN 74 CHEST HOSPITAL OUT-PATIENTS SUFFERING FROM CHRONIC BRONCHITIS AND EMPHYSEMA OR PULMONARY TUBERCULOSIS
Author
No. reported
Swyer and James .. Macleod Belcher and Pattinson ii Dornhorst et aI. . . . . Dgilvie . . . . . . Present series .. ..
I
I
I3 3 4 7 I5
4
rotal
43
26
17
74
74
Ii
. . . . . .
Control series . . . .
No. questioned
Childhood illness
O
artery affected. The forced expiratory spirogram is sometimes characteristic: a sharp descent as the healthy lung empties, followed by an unusually sharp deflection as air trapped in the abnormal lung interferes with further emptying of the healthy lung and slowly makes its own contribution. This interference may be critical if the other lung is affected by airway disease such as chronic bronchitis and emphysema. Whatever the cause of the lesion, the presence of a hypoplastic pulmonary artery is of practical importance. Some patients are symptom free and may never develop respiratory distress. The onset of inflammatory or neoplastic processes in the only functioning lung is of much graver import than in the average patient and requires prompt treatment. Coexisting bronchiectasis can be treated on its merits, bearing in mind that one area of lung (which may or may not be the segment most severely affected by the bronchiectasis) is almost functionless because of the arterial hypoplasia. I f there is effort intolerance (the patient is unable to maintain normal walking pace) and severe trapping in the abnormal lung, then pneumonectomy
262
BELCHER~ CAPEL, PATTINSON AND SMART
may help. This was carried out in 2 of our patients. The improvement in Case I I was great while in Case i o it was slight. In neither case was there any significant change in the spirometry findings after pneumonectomy. This reflects the severe ventilatory defect of the removed lung. The diagnosis of the condition is essentially radiological. The presence of hypoplasia of the pulmonary artery should be suspected whenever a lobe or lung shows increased radiolucency and diminished size. A close study of the vascular pattern on the P.A. chest film will usually establish the diagnosis. Angiography is helpful in doubtful cases, especially if there is difficulty in distinguishing between hypoplasia and congenital absence of the artery to one lung, although in practice the functional difference is often slight.
Summary I. Thirteen new cases of unilateral increased radiolucency of the lung (Macleod's syndrome) are reported. 2. Bronchography, bronchospirometry and angiography were carried out in the majority of the cases. 3- All cases were shown to have small pulmonary arteries in the affected area. In 9, lobar arteries were involved, and in 4 the whole artery on one side was affected. 4- In 2 cases the bronchogram was normal. In the remainder the abnormality was not that of typical bronchiectasis. 5. Bronchospirometry showed that the oxygen uptake was reduced considerably more than the ventilation on the affected side. 6. The ~efiology is discussed. It is thought that the condition may be congenital in origin or that it may be acquired during the growing period. 7. The abnormality does not cause symptoms but it m a y aggravate breathlessness due to disease in the unaffected lung. 8. The practical significance of the anomaly and its treatment are discussed. We thank our colleagues who have referred cases to us. REFERENCES ]3ELCHER, J. R.., and PATTINSON, J. N. (1957) : ~. thor~. ~urg., ~ 357. Bj61~K, V. O., and SALF, N, E. F. (1950) : .7. thora¢. $urg., 2o, 933. CAPEL, L., and SMART, J. (i958) : Lancet, 2, 771. DORNHORST, A. C., HEAF, P. J., and SEMPLE, S.J. (1957) : Lancet, ~, 873. "F~MANUEL,R., and PATTINSON,J. N. (t956): Brit. Heart3., x8, 289. C1OODWIN,J. F., STmNER,R. E., and LowE, K. G. (x952) : 07. Fae. Radiol. (Lon&), 4, 2I. M_~oFF, I. M., G~NSLER, E. A., and STm~XD~R,J. W. (x952) : New EngL 07; Med., 247, x49. MACL~OD,W. M. (I954): Thorax, 9, I47.
Oamvm, C. M. (i959): Personal communication. S~_~mo, R., and RmLBR, L. G. (I948) : Amer. 07. Roentgenol., 6o, 460. SMART,J., and PATTmSON,J. N. (I956) : Brit. med. 07., x, 49 L SwYER, P. R., and JAMES,C. W. (I953): Thorax, 8, I33.
HYPOPLASIA OF THE PULMONARY ARTERIES BY j . R. BELCHER, L. CAPEL, J. N. PATTINSON AND J. SMART From the London Chest Hospital, London, E.2 THE term " unilateral emphysema " has been used to describe a group of cases which presents with increased radiolucency of part or the whole of one lung. Although emphysema is usually a generalised disease, it may be confined to one segment of the lung. When this is the case, that segment occupies more space than normal and this can readily be recognised on a radiograph. Emphysema is, however, but one of a variety of pathological processes which may produce increased radiolucency. This appearance is due to a decrease in the size and number of the pulmonary blood vessels in the area. It may be seen in bronchiectasis, or in bronchogenic carcinoma, due to spreading out of the vessels secondary to compensatory expansion in a lobe adjacent to the collapsed segment. Less frequently, areas of increased radiolucency may occur in a bronchiectatic lobe itself. When partial bronchial obstruction is present overdistension of the lobe distal to the block gives rise to increased radiolucency accompanied by displacement of adjacent structures. Diminished vascularity may also be caused by thrombosis of a pulmonary artery (Shapiro and Rigler, 1948 ) or by neoplastic occlusion of the artery. There is another group of cases, forming the subject of this paper, in which the pulmonary artery in the affected segment is hypoplastic. The characteristic radiological features are: I. The whole of one pulmonary artery, or of one of its lobar branches, is diminished in size. The segmental arteries are also reduced in size and in number. 2. Increased radiolucency of one lung or of one or two of its lobes is evident, owing to this decrease in vascularity. 3. The affected area of lung is decreased in size. Since the publication of 3 cases of hypoplasia of a lobar pulmonary artery in 195 7 we have collected a further 9 examples, and also 4 additional cases in which the whole o f the pulmonary artery on one side was affected. CLINICAL PRESENTATION The details of the presentation of these 13 new cases is given in Table I. Only one was a w o m a n and this dominant male incidence was also seen in other published series (Table II). The average age of the patients was 45 years, with extremes of 18 and 58 . The condition was discovered either at routine X-ray or following the development of the variety of symptoms for which (Receivedfor publication February 28, x959.)
BELCHER~ CAPEL~ PATTINSON AND SMART
254
TABLE I.--SUMMARY OF THE HISTORY AND FINDINGS IN THE 13 PATIENTS
Case Age Sex No. iyrs.
Site
Anglo
I
58
M.
R.L.Z.
+
2 3
49 42
M. M.
L.L.Z. R.L.Z.
+ +
4
39
M.
R.L.Z.
+
5
54
M. R.L.Z.
+
6
28
M.
L.L.Z.
+
7
46
M. R.L.Z.
+
8
45
M.
R.L.Z.
+
9
49
M.
R.L.Z.
+
IO
49
M. !L. lung
+
II
55
M.
L. lung
+
I2 I3
4I 32
F. M.
R. lung L. lung
O O
I
Effort Childhood disability illness
Bronchogram
Peripheral Mild o "blobs" Normal o o No dilatation o at 2 yrs. Slight crowding A few "blobs" Moderate o peripherally Mod. tubular Severe o dilatation Mild tubular o at I yr. dilatation Normal o o No dilatation o o Slight crowding One large "blob" Mild o Spidery bronchi Spidery bronchi Moderate at 8 yrs. Moderate tubular Moderate at 8 yrs. dilatation in L. lower lobe only O o o o o O
History 5 weeks cough. Chest pain. Productive cough. 2o years increasing bronchitis. 20 years increasing bronchitis. Cough and haemoptysis. Cough and haemoptysis. I o years cough. Cough and dyspncea. Progressive dyspnoea. Increasing bronchitis. No symptoms. No symptoms.
TABLE II.--SUMMARY OF CASES PREVIOUSLY REPORTED
Author Swyer and James .. Dornhorst et al.
..
Age
Sex
Site
Comments
6
M.
lZ. lung
Three attacks of pneumonia.
17
M.
L. lung
Dyspnoea. Pneumonia at. 7 and
35 ? ?
M. M. F.
R. lung R.U.L. L. lung
Dyspnoea. Cough and sputum. Mass X-ray.
41
F.
L. lung
25 32 34 4° 32 35 I8 I8
F°
M. M. M. M. M. M. M.
L. R. R. L. L. R. L, L.
Progressive dyspnoea and bronchitis. Cough. Cough and haemoptysis. Dyspnoea. Cough and dyspnoea. Cough, dyspnoea and wheeze. Dyspnoea and bronchitis. Mass X-ray. Mass X-ray.
II.
Macleod
....
lung lung lung lung lung lung lung lung
HYPOPLASIA OF THE PULMONARY ARTERIES
255
patients are referred to a chest clinic (Table III). There was no characteristic history, but on direct questioning 4 patients recalled a " severe chest infection " during childhood or adolescence. TABLE III.--SUMMARY OF THE CLINICAL PRESENTATION IN THE 13 PATIENTS
One lobe affected History of chest in childhood Dyspnoea " Bronchitis " Hmmoptysis No symptoms
infection . . . . .....
One lung affected
2
4
. . . .
io 2 o
. . . . . . . .
SITE
O f the 9 cases in which a lobar artery was affected, 7 were on the right side and the lower lobe trunk was involved in all. In the 4 in which the whole pulmonary artery on one side was affected, one was on the right and 3 were on the left. RADIOLOGICAL
APPEARANCES
Increased radiolucency was present in about half of the lung in 9 cases (Fig. i)* and throughout the whole lung in 4 (Fig. 2). The pulmonary artery in the affected lung or lobe was decreased in size at its root. Its branches were reduced both in number and in size. When the whole pulmonary artery on one side was involved, the contralateral artery and its branches were enlarged (Fig. 2). The lung or lobe affected was reduced in size, as shown by the elevation of the dome of the diaphragm, displacement of the mediastinum towards the affected side, and by the position of the interlobar fissures. The diminished size of the pulmonary artery was evident on a plain P.A. radiograph, but tomography was useful in confirming this. On fluoroscopy of the patients with the whole of one lung affected, the mediastinum was seen to swing away from the lesion during forced expiration. This was accompanied by an unusual increase in density of the vascular markings in the good lung. During forced inspiration, the mediastinum appeared to swing towards the lesion: this might have been merely the return of the mediastinum to its normal position after the preceding expiration. These changes in the position of the mediastinum were noted by Macleod (i954). When only a lobe was involved, it was more difficult to detect trapping, as this would have been masked by the normal lobe. Local air trapping may also be masked when there is generalised chronic bronchitis and emphysema. BRONCHOORAPHY
This was carried out on both sides in i I cases, the only exceptions being 2 patients in whom the whole of the fight lung was affected. In the majority * T h e f i g u r e n u m b e r s i n t h e t e x t re fe r t o P l a t e s X K X V I I I - X X X l K .
256
BELCHER, CAPI~L~ PATTINSON AND SMART
the bronchogram was abnormal, but this abnormality in most was not typical bronchiectasis. In one case the bronchi in the affected right lower lobe and in the rest of the right lung were entirely normal. In the left lower lobe, where the arterial pattern was normal, there was mild dilatation of the peripheral parts of the basal bronchi. In another the bronchogram on both sides was normal. Minor to moderate tubular dilatation of lobar and segmental bronchi with poor filling of their smaller branches was observed in only 2 cases. M i n i m a l dilatation of the periphery of the basal bronchi only was seen in one additional case. Bronchial abnormalities of an unusual character were seen in 4 patients, consisting of small rounded areas in which pooling of contrast medium occurred. These " blobs " arose from the 4th to 6th order bronchi and were not confined to the radiolucent segment but were scattered throughout the lung (Fig. 3). T h e " blobs " v a r i e d in n u m b e r and size and in one case only one l a r g e " blob " was present. Crowding of lobar bronchi with very poor filling of their segmental branches, but without bronchial dilatation, was seen in 2 patients. In one case the only abnormality was a generalised reduction in the calibre of the bronchi, which had a " spidery " appearance. This feature was also seen in 2 of the cases described above in which " blobs " arose from minor bronchi. ANGIOGRAPHY
Little has been published on the normal size of the pulmonary arteries and their branches. I n order to interpret the angiographic findings in our series of cases, measurements were made of the pul m onary arteries and their branches in a group of 52 patients who had had angiocardiograms and in w hom there was no reason to believe that the size of the pul m onary vessels was affected by TABLE IV.--MEASUREMENTS OF THE DIAMETER (IN MM.) OF THE PULMONARY ARTERIES T h e s e w e r e o b t a i n e d f r o m t h e a n g i o c a r d i o g r a m s o f 5 2 p a t i e n t s in w h o m t h e r e w a s n o r e a s o n to e x p e c t t h a t t h e p u l m o n a r y arteries w e r e a b n o r m a l .
P.T. R.P.A. R.U.L. R.L.L. )) R.L.L.(2) L.P.A. L.U.L. L.L.L.(,) L.L.L.(2) I
Number of cases Maximum diameter Minimum diameter Mean diameter
51
52
5°
52
50
48
32
47
47
4I
32
i8
25
I6
33
I4
24
I5
I2 i9.i
Io i~.76
I8 6 24"77 xo.4
I2 I7.72
I I "2~
I8 22 30"77 24.6
7 12"2 5
7
disease. T h e points at which the arteries were measured on the angiograms are shown on Fig. 4 and the findings are recorded in Table IV. Measurements of the pulmonary arteries were also taken in 12 post-mortem specimens (Table V). It can be seen that there is a close correlation between the angiographic and post-mortem measurements of the pul m onary arteries in normal lungs.
PLATE X X X V I I I
FIG. I . - - A radiograph showing increased radiolucency of the right lower lobe and a small lobar artery.
Fro. 2 . ~ A radiograph showing increased radiolucency of the whole left lung. The left pulmonary artery is small and the right one large. (Film taken in expiration.)
~
/~-,a
v ~z_~~_
VLLL,,
l~Io"3.--Case I. A bronchogram showing scattered spherical dilatations o f the peripheral bronchi throughout the whole right lung.
FIG. 4 . - - A diagram to show the points at which the measurements of the pulmonary arteries were made.
To face p.
o56
PLATE XXXIX
FIG. 5.--Case 7- An angiogram showing hypoplasia of the right lower lobe artery (6 ram.).
FIG. 6.--Case i i. An angiogram showing hypoplasia of the left pulmonary artery (I 4 mm. diameter), and a large right pulmonary artery (3 6 mm. diameter).
FIG. 7.--Case I I. A radiograph in inspiration in a case with a small left pulmonary artery.
FIG. 8.--Case I I. A radiograph in expiration showing " trapping ".
257
HYPOPLASIA OF THE PULMONARY ARTERIES
Allowances should be made for slight shrinkage after death and for a radiographic magnification of about 13 per cent. Since the external diameter of the arteries was measured at post-mortem and the internal diameter on the angiocardiogram films, the correction factors tend to cancel one another out. Angiography accurately depicts pulmonary artery size, for stream effects from inadequate mixing of contrast medium and blood do not occur with the intravenous or right atrial injection used in this series. Angiograms were also done in 3 patients before operation for bronchiectasis. The lobar artery in the affected area was reduced in size on the angiogram, and here again the measurements corresponded closely with those on the specimen. TABLE V.--PuLMONARY ARTERY DIAMETERS
Post-mortem number
37 I 372 373 376 377 380 386 388 39° 392 378 379
P.T. L.P.A. R.P.A.
Pulmonarytrunk ext. diam. (mm.)
Right pul. artery ext. diam. (mm.)
Left pul. artery ext. diam. (mm.)
37 32 3o 28 29 3° 27 3I 32 34 28 35
25
27
20 20 20 21
22 20
Max.
Min.
37 ram. 27 mm. 26 mm.
27 ram. 18 mm. 19 mm.
24 19 23 2x
26 21 26
22
19 22 x8 25 20 25 18 22
Mean
31 ram. 22"5 mm. 22.2 mm.
Angiograms in several cases of emphysema were studied. The right and left pulmonary arteries were enlarged whilst their lobar branches gradually tapered down in size from their origins, which were more or less normal in diameter. The major abnormality was seen in the segmental and more peripheral arteries, which were much reduced in size and number. Angiograms Were obtained in x I of our cases with hypoplasia of the pulmonary arteries, and measurements of the diameter of the pulmonary vessels taken at the points indicated in Fig. 4 are shown in Table VI. The affected artery was greatly reduced in size at its origin (Figs. 5 and 6) and its branches were reduced in size and number. In the affected area the circulation rate was invariably sIower than normal, often markedly so. This phenomenon is also seen in emphysema and bronchiectasis. VOL. LIII. 3
4
258
BELCHER, CAPEL, PATTINSON AND SMART TABLE VI.--DIAMETER OF THE HYPOPLASTIC PULMONARY ARTERIES COMPARED WITH THE CORRESPONDING ARTERY ON THE OPPOSITE SIDE. MEASUREMENTS OBTAINED FROM ANGIOORAMS AND GIVEN IN MM.
Case number
Arteryto R.L.L.(e)
Artery to L.L.L.(e)
5
14
I2
6
6 9 6
IO 2o
3tO
I5 7 I4 I5
5
II
Right pulmonary artery
pulmonary artery
I3 6
IO II
I2
I3
Left 2O
34 36 No angiogram No angiogram
z4
Average diameter of the nine hypoplastic lobar arteries = 6"7 mm. Average diameter of the corresponding contralateral arteries = 13-8 mm. LuNG
FUNCTION
STUDIES
O f the 9 patients with one lobe only involved, 5 were investigated by spirometry and bronchospirometry and 4 by fluoroscopy. O f the 4 patients with the whole of one lung involved, all were investigated by spirometry and fluoroscopy, and the 2 patients who later underwent pneumonectomy were also investigated by bronchospirometry. After operation their simple spirometry was repeated. The results are shown in Table VII. The essential functional defect was a great reduction in oxygen uptake with marked, moderate or slight reduction in the tidal volume of the affected area when compared with the rest of the lung. These changes are also seen in bronchiectasis. These defects were revealed by bronchospirometry. In the 2 cases in which the whole of one lung was involved, and where therefore there was no contribution from a normal lobe to mask the defect, oxygen uptake was about 5 per cent. of the total, while the tidal volume was 13 per cent. and 23 per cent. of the total. Where only one lobe was affected, similar defects were present but partly masked by the contribution of the unaffected part of that lung. Tidal volume was reduced in all. PATHOLOGY
Four specimens in all are available for histological study, 2 from this series and 2 from the series reported in 1957. The findings will be "reported in detail by Dr. Lynne Reid in a separate publication.
14YPOPLASIA OF T H E P U L M O N A R Y ARTERIES
259
TABLE VII.--LuNG FUNCTION STUDIES
Bronchospirometry Lung zone ~umber affected I 2
3 4 5 6 7 8
9 IO II I2
13
R:L.Z. L.L.Z. R.L.Z. R.L.Z. R.L.Z. L.L.Z. R.L.Z. R.L.Z. R.L.Z. L. lung Post-opm L. lung Post-opn. R. lung L. lung
Trapping on fluoroscopy
Oxygen uptake %
Tidal
F.E. V
F.E.R.
V.C. %
Trap.
R . 22~o
R. 37%
+
lO5O
50
R. 39%
L. 40%
R. R. R. L.
o o +++ +
151o lO6O 580 2760
52 50 45 61
++ +++
L. 32%
+
+++
L. 5%
L. 26%
++ +
lO3O I24O 123°
6o
L. o t o IO
++ ++
++ +++
volume %
R. 3o% R.
5%
46% 35% 20% 5I%
IOOO IOOO
16oo
m
19oo
63 61 5° 5° 67 61
TheForcedExpiratoryRatio(F.E.R. = one second forced expiratory volume as a percentage of forced vital capacity) is above 7° per cent in healthy people. When the F.E.R. is below 60 per cent., obstructive airway disease is usually present, and as its severity increases the F.E.R. drops towards 30 per cent (Capel and Smart, 1958). At bronchospirometry the tidal volume, oxygen uptake and vital capacity of the right lung is usually found to be 55 per cent. of the total in health. Discussion
T h e 13 cases described here h a d certain radiological features in c o m m o n : increased r a d i o l u c e n c y of the whole or p a r t o f one lung, decrease in size o f the affected segment a n d great r e d u c t i o n in size Of the p u l m o n a r y arteries. T h e y resemble the cases described b y M a c l e o d (I954) , who c o m m e n t e d on the paucity of vascular markings in his series. A n g i o g r a p h y , done in I I o f o u r 13 cases, showed a great reduction in the size a n d n u m b e r o f the p u l m o n a r y arteries and a diminished circulation rate in the affected area. T h e angiographic appearances differed f r o m those seen in e m p h y s e m a in t h a t the affected p u l m o n a r y a r t e r y was small at its origin. I n e m p h y s e m a the p u l m o n a r y a r t e r y is often enlarged up to the origin of its lobar branches. T h e lobar arteries are more or less n o r m a l in d i a m e t e r at their c o m m e n c e m e n t a n d gradually t a p e r off peripherally. T h e e m p h y s e m a t o u s lobe or lung is also increased in size. T h e small size o f the p u l m o n a r y a r t e r y is not a s e c o n d a r y change due to bronchiectasis, for the b r o n c h o g r a m was n o r m a l in 2 o f o u r cases and bronchial dilatation was absent in a n o t h e r 2. T h e p u l m o n a r y a r t e r y supplying a grossly diseased lung u n d o u b t e d l y becomes r e d u c e d in size, b u t seldom below 60 per cent. o f its n o r m a l d i a m e t e r (Bj6rk a n d Saldn, 1950). I n our series o f h y p o p l a s t i c arteries the average d i a m e t e r of the affected lobar arteries at their origin was 6" 7 ram. while the corresponding contralateral vessels averaged i3.8 m m .
260
BELCHER, CAP]EL~ PATTINSON AND SMART
(Table VI). Such a prominent reduction in size (over 5 ° per cent.) is seldom seen even in severe bronchiectasis. A diminution in the size and number of the peripheral pulmonary arteries is seen in primary and secondary pulmonary hypertension. These changes, however, are bilateral and the reduction in calibre occurs distal to the second subdivision of the artery. The main pulmonary arteries and their lobar branches are enlarged (Goodwin, Steiner and Lowe, i952 ). Similar changes may be produced by multiple peripheral emboli or thromboses. The anglographic appearances in these conditions are quite different from those seen in our cases. We suggested in a previous paper (Belcher and Pattinson, I956 ) that a congenital origin was the most likely cause of the arterial hypop!asia and that infection and bonchiectasis might be complicating factors. Since congenital absence of the pulmonary artery to one lung may occur (Madoff and others, i952; Emanuel and Pattinson, I956), it is probable that congenitally small arteries also exist. When one pulmonary artery is congenitally absent, the affected lung is small. Diminished size of that portion of the lung supplied by the hypoplastic artery was a constant feature in our cases. A congenital defect in the form of abnormal interlobar fissures was seen in 2 of our previously reported cases. In our cases in which the whole of the pulmonary artery on one side was small, the contralateral artery was enlarged (Fig. 6), suggesting that the hypoplasia was at least of long-standing. Such enlargement is seldom seen even m a n y years after pulmonary resection in children, and even then not to a marked degree. Smart and Pattinson (1956) reported a case of congenital absence of the left pulmonary artery. Oxygen uptake by the left lung was nil, while the tidal volume was only slightly reduced. Similar results were obtained in 3 other unpublished cases. Therefore complete absence of a pulmonary artery will not of itself necessarily cause a ventilatory defect. In one patient previously reported (Case 3 in I957) there was a marked loss of oxygen uptake in the presence of a normal tidal volume. In such cases the lesion may be solely congenital in origin. When both ventilation and oxygen uptake are defective, the lesion may be due to an acquired ventilatory defect complicating a congenital arterial anomaly, but the possibility that the lesion is entirely acquired cannot be excluded. The abnormality in some cases might be due to lung damage suffered during the growing period. This possibility is favoured by the relative frequency with which serious chest illness in childhood has been reported in this condition (Table VIII). The strongest argument against a congenital mtiology is that the condition has never been reported in infancy. Hypoplasia of the artery, however, is not in itself responsible for symptoms, and the abnormality may easily be overlooked on a chest radiograph. In several of our cases the appearances on previous radiographs had been ignored or misinterpreted. It is also very probable that the small size of the arteries will be missed at routine post-mortem, particularly when lobar arteries alone are involved. Symptoms due to secondary or unrelated pulmonary disease frequently
26I
IIYpoPLASIA OF THE PULMONARY ARTERIES
appear for the first time in men between the ages of 4 ° and 5° years. As a result, most of our patients and those in other reported series were men in their early forties who presented with a variety of chest complaints (Table III). Although the abnormal lobe or lung in itself causes no symptoms, the respiratory reserve is diminished, for the affected area takes up little oxygen (Table VII). Thus the respiratory effort required to fill the useless part of the lung is wasted. If then the respiratory reserve in the rest of the lungs becomes reduced from whatever cause (such as chronic bronchitis), the presence of the abnormality will contribute indirectly to the breathlessness. It will do so not only because of the loss of respiratory reserve, but also because in some cases it may diminish the ventilation of the other lung. It may do this if air trapping during exercise causes a mediastinal shift towards the normal lung (Figs. 7 and 8). Trapping was present in each of the 4 patients with the whole of the right or left pulmonary TABLE V I I I . - - I N C I D E N C E OF SEVERE ILLNESS IN CHILDHOOD IN 43 PATIENTS WITH UNILATERAL HYPOPLASIA OF A PULMONARY ARTERY, OF WHOM 06 WErE QUESTIONED, .AND IN 74 CHEST HOSPITAL OUT-PATIENTS SUFFERING FROM CHRONIC BRONCHITIS AND EMPHYSEMA OR PULMONARY TUBERCULOSIS
Author
No. reported
Swyer and James .. Macleod Belcher and Pattinson ii Dornhorst et aI. . . . . Dgilvie . . . . . . Present series .. ..
I
I
I3 3 4 7 I5
4
rotal
43
26
17
74
74
Ii
. . . . . .
Control series . . . .
No. questioned
Childhood illness
O
artery affected. The forced expiratory spirogram is sometimes characteristic: a sharp descent as the healthy lung empties, followed by an unusually sharp deflection as air trapped in the abnormal lung interferes with further emptying of the healthy lung and slowly makes its own contribution. This interference may be critical if the other lung is affected by airway disease such as chronic bronchitis and emphysema. Whatever the cause of the lesion, the presence of a hypoplastic pulmonary artery is of practical importance. Some patients are symptom free and may never develop respiratory distress. The onset of inflammatory or neoplastic processes in the only functioning lung is of much graver import than in the average patient and requires prompt treatment. Coexisting bronchiectasis can be treated on its merits, bearing in mind that one area of lung (which may or may not be the segment most severely affected by the bronchiectasis) is almost functionless because of the arterial hypoplasia. I f there is effort intolerance (the patient is unable to maintain normal walking pace) and severe trapping in the abnormal lung, then pneumonectomy
262
BELCHER~ CAPEL, PATTINSON AND SMART
may help. This was carried out in 2 of our patients. The improvement in Case I I was great while in Case i o it was slight. In neither case was there any significant change in the spirometry findings after pneumonectomy. This reflects the severe ventilatory defect of the removed lung. The diagnosis of the condition is essentially radiological. The presence of hypoplasia of the pulmonary artery should be suspected whenever a lobe or lung shows increased radiolucency and diminished size. A close study of the vascular pattern on the P.A. chest film will usually establish the diagnosis. Angiography is helpful in doubtful cases, especially if there is difficulty in distinguishing between hypoplasia and congenital absence of the artery to one lung, although in practice the functional difference is often slight.
Summary I. Thirteen new cases of unilateral increased radiolucency of the lung (Macleod's syndrome) are reported. 2. Bronchography, bronchospirometry and angiography were carried out in the majority of the cases. 3- All cases were shown to have small pulmonary arteries in the affected area. In 9, lobar arteries were involved, and in 4 the whole artery on one side was affected. 4- In 2 cases the bronchogram was normal. In the remainder the abnormality was not that of typical bronchiectasis. 5. Bronchospirometry showed that the oxygen uptake was reduced considerably more than the ventilation on the affected side. 6. The ~efiology is discussed. It is thought that the condition may be congenital in origin or that it may be acquired during the growing period. 7. The abnormality does not cause symptoms but it m a y aggravate breathlessness due to disease in the unaffected lung. 8. The practical significance of the anomaly and its treatment are discussed. We thank our colleagues who have referred cases to us. REFERENCES ]3ELCHER, J. R.., and PATTINSON, J. N. (1957) : ~. thor~. ~urg., ~ 357. Bj61~K, V. O., and SALF, N, E. F. (1950) : .7. thora¢. $urg., 2o, 933. CAPEL, L., and SMART, J. (i958) : Lancet, 2, 771. DORNHORST, A. C., HEAF, P. J., and SEMPLE, S.J. (1957) : Lancet, ~, 873. "F~MANUEL,R., and PATTINSON,J. N. (t956): Brit. Heart3., x8, 289. C1OODWIN,J. F., STmNER,R. E., and LowE, K. G. (x952) : 07. Fae. Radiol. (Lon&), 4, 2I. M_~oFF, I. M., G~NSLER, E. A., and STm~XD~R,J. W. (x952) : New EngL 07; Med., 247, x49. MACL~OD,W. M. (I954): Thorax, 9, I47.
Oamvm, C. M. (i959): Personal communication. S~_~mo, R., and RmLBR, L. G. (I948) : Amer. 07. Roentgenol., 6o, 460. SMART,J., and PATTmSON,J. N. (I956) : Brit. med. 07., x, 49 L SwYER, P. R., and JAMES,C. W. (I953): Thorax, 8, I33.