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Chest deformities in congenital heart disease
Brit. J. Dis. Chest (I959) 53, I5x.
CHEST DEFORMITIES IN CONGENITAL H E A R T DISEASE BY HYWEL
DAVIES
From the Universityof Colorado Medical Centre,Denver, Colorado,U.S.A., and
The National Heart Hospital, London INTRODUCTION SO~E children with congenital heart disease have chests of unusual shape. Hitherto no attempt seems to have been made to relate these changes to the underlying pathology. The present study was undertaken with this in mind, and was initiated by some clinical observations on children with septal defects. The first patient was a child of seven who had recently undergone surgery for closure o f a ventricular septat defect, using cardiac bypass and a pump oxygenator. He was extremely dyspnceic, and the small chest appeared blown-up and barrel-shaped. The sternum jutted forward and was lifted laboriously with each breath; at the same time the lower ribs were sucked in during inspiration. The picture was at once reminiscent of the severe respiratory embarrassment of an asthmatic attack, or of the exacerbations of illness in patients with chronic bronchitis and emphysema. It became apparent that this respiratory distress was much more common in children with ventricular septal defects (V.S.D.) than in those with atrial septal defects (A.S.D.) at a corresponding post-operative stage, and that this could not be accounted for entirely by the diminished trauma and metabolic upset occasioned by the techniques of hypothermia as compared with the artificial cimulafion. When it was observed that children with V.S.D. had, by and large, a different chest shape from those with A.S.D., the question arose as to whether or not there was any reladon between the chest deformity and the nature of" the cardiac lesion, and, if so, whether any significance could be attached to this in view of" the manifest differences in behaviour of the two conditions. The contour of the chest in the sagittal plane is fairly accurately represented in the lateral chest X-ray, and it is on this basis that the study has been carried out. Before describing the methods and results, the clinical features of the chest deformities will be described. In patients with an A.S.D. a chest deformity is present in about one-half of the cases (Taussig, 1947; Swan et al., 1959). This deformity consists of a protuberance in the region to the left of the lower sternum where the pulsation of the right ventricle is felt. The upper sternal region is usually normal or flat and tends to be narrow in the antero-posterior diameter, the bulge being low and unilateral (Fig. 4).* In the V.S.D., on the other hand, the sternum itself appears to bulge high in its contour, the lower regions being rather indrawn. Furthermore, the prominence is usually bilateral. Sometimes * The figure numbers in the text refer to Plates VII and VIII. (Receivedfor publication Wovember28, I958.)
I52
DAVIEs
the angle between manubrium and sternum is sharp; sometimes the convexity forward assumes the form of an arc embracing the whole of the anterior chest from supra-sternal notch to ziphisternum. These differences are recognisable clinically without great difficulty.
MATERIAL
AND M E T H O D S
The chest X-rays of IOO cases of A.S.D. and approximately IOO of V.S.D. have been examined. All these patients had undergone cardiac catheterisation. Only those in whom an adequate lateral X-ray was available have been retained in the study, as obliquity distorts the sternal contour. When this criterion had been satisfied, there remained 80 cases of A.S.D. and 45 of V.S.D. The former ranged in age between I year and 45 years, whilst all the latter were between 3 and 14 years of age except case 45, who was 24 years old. An attempt was made at first to record accurately, in terms of angles and ratios, the mensural characteristics of the X-rays, but this was found to be unrewarding, owing to the variations in shape, posture and size. Accordingly, the degree of upper sternal prominence has been g r a d e d " b l i n d " (i.e. without knowledge at the time of the diagnosis or the h~emodynamic findings) into " severe," " moderate " or " absent". Those cases in whom the deformity was thought to be only mild have been included in the latter group. It is emphasised that the deformity sought has been that of the " V . S . D . t y p e " described above. Examples of the X-ray appearances are shown in Fig. I (severe) and Fig. 2 (moderate deformity). Fig. 3 shows, for contrast, a normal lateral X-ray of a patient with V.S.D. (case 28), and Fig. 4 that of a case of A.S.D., showing that the lower sternal contour appears bifid on account of the unilateral protuberance. Results Severe upper sternal deformity (V.S.D. type) (Fig. I) was present in I I of the 45 cases of V.S.D. and in none of the A.S.D. cases. Moderate deformity was seen (Fig. 2) in a further i i cases of V.S.D., and again in none of the A.S.D. cases. Thus, the deformity was seen in 22 of the cases of V.S.D. as compared with none in A.S.D. The results are summarised in Table I. TABLE I.--INcIDENCE OF " V.S.D.-TYPE " DEFORMITY
IN 45 CASESOF V.S.D. AND 8O OF A.S.D.
Severe deformity .... Moderate deformity . . . . No deformity . . . . . .
V.&D.
A.S.D.
Cases
Cases
II II
O O
23
8o
45
8o
PLATE X X I I
FIG. I.--Three cases of severe deformity (V.S.D. type).
chest
FIG, 2.--Three cases of moderate chest deformity (V.S.D. type). To face p, 15
PLATE X X I I I
FIG. 3.--Normal lateral chest X-ray of patient with V.S.D.
FIG. 4.--Case of A.S.D. showing that sternum appears bifid on account of unilateral protuberance.
GHI~ST DEFORMITIES IN CONGENITAL HEART DISEASE
15 3
TABLE [I,--H2EMODYNAMIC DA~rA IN 45 CASES OF V . S . D . (PULMONARY INDEX IN LITRES/MIN./M z. RESISTANCE IN DYNES-SEC.-CM,'5-M 2 I
Casg
number 1
2
3 4 5 6 7 8
9 IO II
Average
Pulmonary artery pressure (mm.)
Pulmonaryflow Systemicflow
55/3 ° Ioo/5o 9o/55 35/20 80/50 9o/45 95/55 9o/5o 85/45 mo/5o 9o/5o
2. 5 4"5
68o 85o 65o 60o
2"3
8"9
580
2.8
14.8
3o0
3"I 1"5 1"6 5-o
9.o 4"0
?
6-6 7"5 9-6 I5"4 ?
550 950 25° 225 425 725 55o 550 35o ?
2.5
lO. 7
485
3"0
5° 225 I5o
2.6 1.6
25 I5 5"6 ? 7"5 23"5 i2-2 7"5 6. 3 7.2 6. 5
25/Io
I" 3
5-0
58 (mean)
Average
57 (mean)
23 24 25 26 27 28 29 3° 3I 32 33 34 35 36 37 38 39 4° 4I 42 43 44 45
3o/15 8o/25 15/8 I5/6 I8/5
20/10
I'I
55/2o I 10/65 55/3o 25/15 65/5o 7o/4o 55/25 25/IO 85/45 50/20
4"o I" 9 8'0 I" 4 3"0 I" 3 3'2
Average
28 (mean)
2"9
20/IO 17/5
65/3 ° 25/I5 4o/I5
35/5
4"0 1.7 1.6 1.6 ~'O
4"4 1"8 1, 5 o. I 8-0
2"7 2"5 I'2
4"5 3"3 1"4
8"0
IO'O
16.5 I4"O
3"6 IO"1 5"1
35"0 6. 7 7"7 6. 5 io. 7 20.6
Severity Severe
37° ? 7oo
13.2 I2.8 8. 3 7"5 • 7"4 5"5 8"3 8. 5
20 2I 22
VOL. LIII. 2
9"3 ?
Total pulmonary resistance
I'6 2. 4 3. 0 ~'3 2"0 2"o 1. 3 1"7 ~'o
80/45 90/45 80/30 55/20 80/30 1 I5/55 80/50 70/4° 95/5o 9o•55 95/60
I3 I4 15 I6 I7 I8 I9
Pulmonary index
I5o 4oo 6oo 8o0
Moderate
(
Absent
?
IOO
5o 6o 45o 250 200 200 250 3OO 250
I25 ° IOO 225
575 6oo 250
IO'O 4"O
6o 45o 6oo
I I'O
3O0
I
154
DAVIEs
Table II gives details of the cases of V.S.D. and relates the findings to the h~emodynamic data obtained at cardiac catheterisation. O f the i I cases with severe chest deformity, all had marked pulmonary hypertension (defined simply as an elevated pulmonary artery pressure) except one (case 4). This was the youngest patient, being aged 3; his pulmonary flow was high though the resistance still relatively low. In this group all had an increased pulmonary blood flow (average 8. 9 lit./min./mZ), and all save one an increased pulmonary vascular resistance (average 580 dynes-sec.-cm.-S-m~). O f I I cases with moderate chest deformity, all had pulmonary hypertension (average mean pulmonary artery pressure 57 mm. Hg). The average pulmonary blood flow was I o. 7 lit./min./m 2, and the average pulmonary vascular resistance was 485 dynes-sec.-cm.-5-m2. O f 23 cases without marked chest deformity, only 6 had a mean pulmonary artery pressure greater than 35 ram. Hg; the average was 28 ram. Hg. The average pulmonary blood flow was I i- o lit./min. ]m ~, and the average pulmonary resistance 300 dynes-sec.-cm.-S-m2. It is evident, therefore, that this type of chest deformity (V.S.D. type) occurs in about one-half of the cases of V.S.D. analysed on the basis of" the lateral chest X-ray. In this group the mean pulmonary artery pressure and total pulmonary resistance are approximately twice as high as in the group in which the deformity is mild or absent. EISENMENGI~-R~S COMPLEX
Six cases fulfilled the necessary criteria of an adequate lateral X-ray and h~emodynamic data, and in these the deformity was present to moderate degree in only one. The other five had normal chests. This finding is in keeping also with clinical observation.
Discussion Why should there be such a difference between the chest configuration of the patient with an A.S.D. and the one with a V.S.D.? In the case of the former lesion, the deformity is explicable on the basis of direct pressure by the enlarged right ventricle on the malleable structures of the thoracic cage in childhood. The bulge occurs in the region just over the right ventricle. (Recently a patient with an A.S.D. was seen in whom the heart lay to the right of the sternum; in this case the bulge was right-sided.) W h y t h e deformity occurs in some cases of A.S.D. and not in others is not clear, but may be related to the age at whlch significant right ventricular enlargement occurs, in that it is highly likely that the left-to-right shunt is not present at birth, but develops during the first year of life in cases of A.S.D. Examination of cases of V.S.D., however, and consideration of their X,rays leads to the Conclusion that the sternal protuberance in question is not contiguous with the heart or great vessels, and cannot be explained by the factor of
GHI~ST DEFORMITIES IN CONGENITAL HEART DISEASE
I55
direct pressure. The only acceptable explanation must, nevertheless, be based on the idea that the mechanical forces at work in the thorax are different fi:om those in normal children. These forces m a y be intracardiac or extracardiac. Certainly, the V.S.D. differs from the A.S.D. in that a left-to-right shunt at ventricular level is present, and that from birth. It is not commonly realised that the inter-ventricular septum lies virtually in the frontal plane, i.e. parallel to the anterior chest wall, not at right-angles to it. The right ventricle lies anterior to the septum, and the left ventricle posterior to it. Hence a shunt which is functionally left-to-right is anatomically postero-anterior, and the jet of blood is thrust forwards and upwards, towards the region where the protuberance occurs. It is theoretically possible that this abnormal force could be transmitted to the chest wall and so lead to the deformity in question. However, this seems unlikely to be the explanation on several counts. First, the V.S.D. deformity is strictly bilateral, while the heart is not. Secondly, the deformity occurs much more commonly in association with a high pulmonary vascular resistance than with a low one; most cases with a large left-to-right shunt but low pulmonary vascular resistance have normal chests (e.g. cases 28, 38 and 43)- Thirdly, it seems unlikely that the spongy lung tissue which intervenes between the heart and the upper sternal region would be a sufficiently good mechanical conductor to cause bony deformity. Fourthly, the elastic recoil of the heart would limit this factor. The cause of the phenomenon must, therefore, be sought in the extra-cardiac forces of the thorax, and these, of course, are related to respiration. The respiratory difficulty which occurs after surgery for V.S.D. has been mentioned already, and is one of the major problems which must be faced in the care of these cases. In some centres (Lillehei, i959) the question is taken so seriously that a pre-operative tracheostomy is performed, the trans-sternal incision has been abandoned in favour of a vertical sternal-splitting one which does not involve the pleural cavities, and mechanical aids to respiration are employed post-operativeIy. It seems logical to ask, therefore, whether or not the deformity in question is related to the mechanical properties of the lungs and the work of breathing. I f this were so, it would adequately explain why the bulging is strictly bilateral, why the anteroposterior diameter of the chest is increased, and why there is often sucking-in of the lower ribs. The problem therefore devolves on the mechanical properties of the lungs in cases of V.S.D. This information is not at present available, partly, no doubt, because it is notoriously difficult to perform pulmonary function studies on children. Any reasoning must, therefore, be based on hypothesis rather than fact. On theoretical grounds, it is possible that two factors should operate in these cases to alter the mechanical properties of the lungs. The first of these is the presence of an increased amount of blood in the lungs. The second is that the pulmonary vasculature is abnormal and contains an increased amount of muscle. The ramifying branches of the pulmonary artery serve as a scaffolding for the pulmonary architecture, and increased stiffness of this scaffolding would lead to changes in the physical properties of the lungs. Separately, these two factors m a y have a variable effect, perhaps none. Thus, the pulmonary blood
}~{
DAVIEs
content in atrial septal defect may be very large without making any great difference to pulmonary function. Likewise, some cases of pulmonary hypertension may be associated with relatively normal puhnonary function, as measured by the techniques currently available. Together, however, these two factors could operate to produce changes in the mechanical properties of the lungs, in a manner analogous with such variations in erectile tissue. McIlroy and Apthorp (i958) have studied pulmonary function in patients with pulmonary hypertension and found, in general, a variable reduction in lung compliance, diffusing capacity and ventilation equivalent, with slight increase in inspiratory resistance. Their cases included five with V.S.D., but all these were in the " Eisenmenger group " and none had a pulmonary flow greater than the systemic. In only one of these cases (case I2) was the lung compliance reduced ( i . e . the lungs being " stiffer " than normal). This is in keeping with the observation that a chest deformity is present in only a minority of patients with the " Eisenmenger syndrome " (as defined by Wood, I958), and supports the contention that in these cases the raised pulmonary vascular resistance is present from birth. The finding of a bulging sternum in a patient with t h e " Eisenmenger syndrome " w o u l d suggest that there was at one time a left-to-right shunt. McIlroy and Apthorp (I958) found hyperventilation to be common in pulmonary hypertension. This was not abolished by oxygen, and the stimulus for it is unknown. This would undoubtedly increase the work of breathing. That changes in the properties of the lungs could produce the chest deformity of the V.S.D. is not unlikely. The pigeon-breast, with raised sternum, increased antero-posterior chest diameter, and indrawing of the lower chest wall occurs classically in rickets, being here the response of abnormal bone to normal respiratory forces. (This sternal protuberance was recorded as early as I645 by Whistler.) Naish and Wallis (I948) found, in a study of Harrison's grooves, that they were much commoner in children suffering from asthma than in normal ones, and that their depth depended on how early the disease had started. They also found the grooves to be present in 23 out of 36 cases of congenital heart disease, though the details of diagnosis are not clear. The grooves were also noted frequently in children with a pigeon-breast deformity. A few years earlier, Naish (i945) had recorded marked inspiratory indrawing of the lower intercostal spaces in eight cases of congenital heart disease, seen in infancy, in whom there was no evidence of rickets or of upper respiratory tract infection. This is seen not infrequently in small children with V . S . D . Sheldon (I938) noted the forward bulging of the sternum and costal cartilages in young infants with congenital heart disease, and ascribed it to cardiac hypertrophy. He made the point that there may be collapse of the bases of the lungs due to enlargement of the heart, and noted that in these infants the character of the breathing is often peculiar. It is impossible to deny that this explanation, based entirely on the mechanical effects of an enlarged heart, may be correct. It has the merit of suggesting abnormality of the respiratory apparatus, but is probably an oversimplification. If it were correct that the lungs were stiffer than normal in V.S.D., it would
C H E S T D E F O R M I T I E S IN C O N G E N I T A L
HEART
DISEME
15 7
be expected that the sternal bulging would occur in any case where the essential h~emodynamic requisites are met, viz. increased pulmonary vascular resistance and increased pulmonary blood flow. These factors are present in some cases of patent ductus arteriosus, and indeed the deformity was seen in one such patient. The elevation of the sternum and the insucking of the lower ribs were very marked, as was hyperventilation. This child, aged 3, was operated upon and at the time the surgeon's unsolicited remarks were that " the lungs were stiff." She died soon afterwards. The situation in atrioventricularis communis is similar to that in V.S.D., and the deformity is also seen with this lesion, as it is when a V.S.D. is present together with other lesions, such as patent ductus arteriosus and coarctation of the aorta. In practice, however, the majority of patients with the high sternal protuberance have a V.S.D. That there may be other factors, not at present apparent, is shown by consideration o f case 4, who had severe deformity without much pulmonary hypertension, and cases 37 and 40, who had pulmonary hypertension with increased resistance and flow, but no significant chest deformity. Thus, more work must be done in the study of these deformities before any conclusions become absolute, particularly in relation to pulmonary function and the work of breathing.
Summary The chest deformity associated with the A.S.D. differs clinically and radiologically from that of the V.S.D. In A.S.D. there is a unilateral bulge which lies directly over the right ventricle and is considered to be due directly to the pressure of this enlarged chamber. In V.S.D. there is a bilateral upper sternal protuberance, the antero-posterior diameter of the chest is increased, and there is a tendency for the lower ribs to be drawn in on inspiration. The " V.S.D. type " deformity was found, on a radiological basis, in onehalf of 45 cases of V.S.D. in whom an adequate lateral X-ray of the chest was available, together with cardiac catheterisation data. Thus, the incidence of the " V . S . D . t y p e " deformity in cases of V.S.D. is approximately the same as that of the " A . S . D . t y p e " deformity in cases of A.S.D. In the V.S.D., the deformity, which is similar to a pigeon-breast deformity, was associated in most cases with pulmonary hypertension. It is considered to be much commoner when the pulmonary vascular resistance is raised than when it is not. It occurs in the " Eisenmenger syndrome " in only a minority of cases. It is suggested that the deformity of the V.S.D. may be due to changes in the mechanical properties of the lungs, and that the combination of increased pulmonary vascular resistance and increased pulmonary blood flow increases the stiffness of the lungs. I am much indebted to Dr. S. Gilbert Blount Jr., of Denver, Colorado, for permission to use data from a number ofhis cases; to Drs. Paul Wood and Aubrey Leatham of the National Heart Hospital, London, for like kindness; and to Drs. Peter Kerley and William Evans for their helpful advice.
I 58
DAVIt~s
REFERENCES LILLEnEI, C. W. (I959) : J. thorac. Surg. (In the press.) MCILRoY, M. B., and APTHORP, G. H. (I958): "Pulmonary Function in Pulmonary Hypertension," Brit. Heart J., 2o, 397. NAISH, A. E. (I945): Arch. Dis. Childh., 2o, I85. NAISH, J., and WALLIS, H. R. E. (I948): " The Significance of Harrison's Grooves," Brit. med. J., *, 54 I. S~I~LDON, W. (I955): "Diseases of Infancy and Childhood," 7th ed., p. 43o. London: J. & A. Churchill. SWAM,H., KORTZ,A. B., DAvIBs, D. H ~ L , and BLOUNT,S. GILBERTJr. (I 959) : "Atrial Septal Defect Secundum," 07. thorac. Surg., S7, 52. TAuss1% H. (I947): " Congenital Malformations of the Heart." (Commonwealth Fund) New York. WHISTLER, D. (I645) : Noted by Naish and Wallis, i948. WooD, P. (i958): " The Eisenmenger Syndrome," Brit. reed. o7., 2, 7oi and 755.
CHEST DEFORMITIES IN CONGENITAL H E A R T DISEASE BY HYWEL
DAVIES
From the Universityof Colorado Medical Centre,Denver, Colorado,U.S.A., and
The National Heart Hospital, London INTRODUCTION SO~E children with congenital heart disease have chests of unusual shape. Hitherto no attempt seems to have been made to relate these changes to the underlying pathology. The present study was undertaken with this in mind, and was initiated by some clinical observations on children with septal defects. The first patient was a child of seven who had recently undergone surgery for closure o f a ventricular septat defect, using cardiac bypass and a pump oxygenator. He was extremely dyspnceic, and the small chest appeared blown-up and barrel-shaped. The sternum jutted forward and was lifted laboriously with each breath; at the same time the lower ribs were sucked in during inspiration. The picture was at once reminiscent of the severe respiratory embarrassment of an asthmatic attack, or of the exacerbations of illness in patients with chronic bronchitis and emphysema. It became apparent that this respiratory distress was much more common in children with ventricular septal defects (V.S.D.) than in those with atrial septal defects (A.S.D.) at a corresponding post-operative stage, and that this could not be accounted for entirely by the diminished trauma and metabolic upset occasioned by the techniques of hypothermia as compared with the artificial cimulafion. When it was observed that children with V.S.D. had, by and large, a different chest shape from those with A.S.D., the question arose as to whether or not there was any reladon between the chest deformity and the nature of" the cardiac lesion, and, if so, whether any significance could be attached to this in view of" the manifest differences in behaviour of the two conditions. The contour of the chest in the sagittal plane is fairly accurately represented in the lateral chest X-ray, and it is on this basis that the study has been carried out. Before describing the methods and results, the clinical features of the chest deformities will be described. In patients with an A.S.D. a chest deformity is present in about one-half of the cases (Taussig, 1947; Swan et al., 1959). This deformity consists of a protuberance in the region to the left of the lower sternum where the pulsation of the right ventricle is felt. The upper sternal region is usually normal or flat and tends to be narrow in the antero-posterior diameter, the bulge being low and unilateral (Fig. 4).* In the V.S.D., on the other hand, the sternum itself appears to bulge high in its contour, the lower regions being rather indrawn. Furthermore, the prominence is usually bilateral. Sometimes * The figure numbers in the text refer to Plates VII and VIII. (Receivedfor publication Wovember28, I958.)
I52
DAVIEs
the angle between manubrium and sternum is sharp; sometimes the convexity forward assumes the form of an arc embracing the whole of the anterior chest from supra-sternal notch to ziphisternum. These differences are recognisable clinically without great difficulty.
MATERIAL
AND M E T H O D S
The chest X-rays of IOO cases of A.S.D. and approximately IOO of V.S.D. have been examined. All these patients had undergone cardiac catheterisation. Only those in whom an adequate lateral X-ray was available have been retained in the study, as obliquity distorts the sternal contour. When this criterion had been satisfied, there remained 80 cases of A.S.D. and 45 of V.S.D. The former ranged in age between I year and 45 years, whilst all the latter were between 3 and 14 years of age except case 45, who was 24 years old. An attempt was made at first to record accurately, in terms of angles and ratios, the mensural characteristics of the X-rays, but this was found to be unrewarding, owing to the variations in shape, posture and size. Accordingly, the degree of upper sternal prominence has been g r a d e d " b l i n d " (i.e. without knowledge at the time of the diagnosis or the h~emodynamic findings) into " severe," " moderate " or " absent". Those cases in whom the deformity was thought to be only mild have been included in the latter group. It is emphasised that the deformity sought has been that of the " V . S . D . t y p e " described above. Examples of the X-ray appearances are shown in Fig. I (severe) and Fig. 2 (moderate deformity). Fig. 3 shows, for contrast, a normal lateral X-ray of a patient with V.S.D. (case 28), and Fig. 4 that of a case of A.S.D., showing that the lower sternal contour appears bifid on account of the unilateral protuberance. Results Severe upper sternal deformity (V.S.D. type) (Fig. I) was present in I I of the 45 cases of V.S.D. and in none of the A.S.D. cases. Moderate deformity was seen (Fig. 2) in a further i i cases of V.S.D., and again in none of the A.S.D. cases. Thus, the deformity was seen in 22 of the cases of V.S.D. as compared with none in A.S.D. The results are summarised in Table I. TABLE I.--INcIDENCE OF " V.S.D.-TYPE " DEFORMITY
IN 45 CASESOF V.S.D. AND 8O OF A.S.D.
Severe deformity .... Moderate deformity . . . . No deformity . . . . . .
V.&D.
A.S.D.
Cases
Cases
II II
O O
23
8o
45
8o
PLATE X X I I
FIG. I.--Three cases of severe deformity (V.S.D. type).
chest
FIG, 2.--Three cases of moderate chest deformity (V.S.D. type). To face p, 15
PLATE X X I I I
FIG. 3.--Normal lateral chest X-ray of patient with V.S.D.
FIG. 4.--Case of A.S.D. showing that sternum appears bifid on account of unilateral protuberance.
GHI~ST DEFORMITIES IN CONGENITAL HEART DISEASE
15 3
TABLE [I,--H2EMODYNAMIC DA~rA IN 45 CASES OF V . S . D . (PULMONARY INDEX IN LITRES/MIN./M z. RESISTANCE IN DYNES-SEC.-CM,'5-M 2 I
Casg
number 1
2
3 4 5 6 7 8
9 IO II
Average
Pulmonary artery pressure (mm.)
Pulmonaryflow Systemicflow
55/3 ° Ioo/5o 9o/55 35/20 80/50 9o/45 95/55 9o/5o 85/45 mo/5o 9o/5o
2. 5 4"5
68o 85o 65o 60o
2"3
8"9
580
2.8
14.8
3o0
3"I 1"5 1"6 5-o
9.o 4"0
?
6-6 7"5 9-6 I5"4 ?
550 950 25° 225 425 725 55o 550 35o ?
2.5
lO. 7
485
3"0
5° 225 I5o
2.6 1.6
25 I5 5"6 ? 7"5 23"5 i2-2 7"5 6. 3 7.2 6. 5
25/Io
I" 3
5-0
58 (mean)
Average
57 (mean)
23 24 25 26 27 28 29 3° 3I 32 33 34 35 36 37 38 39 4° 4I 42 43 44 45
3o/15 8o/25 15/8 I5/6 I8/5
20/10
I'I
55/2o I 10/65 55/3o 25/15 65/5o 7o/4o 55/25 25/IO 85/45 50/20
4"o I" 9 8'0 I" 4 3"0 I" 3 3'2
Average
28 (mean)
2"9
20/IO 17/5
65/3 ° 25/I5 4o/I5
35/5
4"0 1.7 1.6 1.6 ~'O
4"4 1"8 1, 5 o. I 8-0
2"7 2"5 I'2
4"5 3"3 1"4
8"0
IO'O
16.5 I4"O
3"6 IO"1 5"1
35"0 6. 7 7"7 6. 5 io. 7 20.6
Severity Severe
37° ? 7oo
13.2 I2.8 8. 3 7"5 • 7"4 5"5 8"3 8. 5
20 2I 22
VOL. LIII. 2
9"3 ?
Total pulmonary resistance
I'6 2. 4 3. 0 ~'3 2"0 2"o 1. 3 1"7 ~'o
80/45 90/45 80/30 55/20 80/30 1 I5/55 80/50 70/4° 95/5o 9o•55 95/60
I3 I4 15 I6 I7 I8 I9
Pulmonary index
I5o 4oo 6oo 8o0
Moderate
(
Absent
?
IOO
5o 6o 45o 250 200 200 250 3OO 250
I25 ° IOO 225
575 6oo 250
IO'O 4"O
6o 45o 6oo
I I'O
3O0
I
154
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Table II gives details of the cases of V.S.D. and relates the findings to the h~emodynamic data obtained at cardiac catheterisation. O f the i I cases with severe chest deformity, all had marked pulmonary hypertension (defined simply as an elevated pulmonary artery pressure) except one (case 4). This was the youngest patient, being aged 3; his pulmonary flow was high though the resistance still relatively low. In this group all had an increased pulmonary blood flow (average 8. 9 lit./min./mZ), and all save one an increased pulmonary vascular resistance (average 580 dynes-sec.-cm.-S-m~). O f I I cases with moderate chest deformity, all had pulmonary hypertension (average mean pulmonary artery pressure 57 mm. Hg). The average pulmonary blood flow was I o. 7 lit./min./m 2, and the average pulmonary vascular resistance was 485 dynes-sec.-cm.-5-m2. O f 23 cases without marked chest deformity, only 6 had a mean pulmonary artery pressure greater than 35 ram. Hg; the average was 28 ram. Hg. The average pulmonary blood flow was I i- o lit./min. ]m ~, and the average pulmonary resistance 300 dynes-sec.-cm.-S-m2. It is evident, therefore, that this type of chest deformity (V.S.D. type) occurs in about one-half of the cases of V.S.D. analysed on the basis of" the lateral chest X-ray. In this group the mean pulmonary artery pressure and total pulmonary resistance are approximately twice as high as in the group in which the deformity is mild or absent. EISENMENGI~-R~S COMPLEX
Six cases fulfilled the necessary criteria of an adequate lateral X-ray and h~emodynamic data, and in these the deformity was present to moderate degree in only one. The other five had normal chests. This finding is in keeping also with clinical observation.
Discussion Why should there be such a difference between the chest configuration of the patient with an A.S.D. and the one with a V.S.D.? In the case of the former lesion, the deformity is explicable on the basis of direct pressure by the enlarged right ventricle on the malleable structures of the thoracic cage in childhood. The bulge occurs in the region just over the right ventricle. (Recently a patient with an A.S.D. was seen in whom the heart lay to the right of the sternum; in this case the bulge was right-sided.) W h y t h e deformity occurs in some cases of A.S.D. and not in others is not clear, but may be related to the age at whlch significant right ventricular enlargement occurs, in that it is highly likely that the left-to-right shunt is not present at birth, but develops during the first year of life in cases of A.S.D. Examination of cases of V.S.D., however, and consideration of their X,rays leads to the Conclusion that the sternal protuberance in question is not contiguous with the heart or great vessels, and cannot be explained by the factor of
GHI~ST DEFORMITIES IN CONGENITAL HEART DISEASE
I55
direct pressure. The only acceptable explanation must, nevertheless, be based on the idea that the mechanical forces at work in the thorax are different fi:om those in normal children. These forces m a y be intracardiac or extracardiac. Certainly, the V.S.D. differs from the A.S.D. in that a left-to-right shunt at ventricular level is present, and that from birth. It is not commonly realised that the inter-ventricular septum lies virtually in the frontal plane, i.e. parallel to the anterior chest wall, not at right-angles to it. The right ventricle lies anterior to the septum, and the left ventricle posterior to it. Hence a shunt which is functionally left-to-right is anatomically postero-anterior, and the jet of blood is thrust forwards and upwards, towards the region where the protuberance occurs. It is theoretically possible that this abnormal force could be transmitted to the chest wall and so lead to the deformity in question. However, this seems unlikely to be the explanation on several counts. First, the V.S.D. deformity is strictly bilateral, while the heart is not. Secondly, the deformity occurs much more commonly in association with a high pulmonary vascular resistance than with a low one; most cases with a large left-to-right shunt but low pulmonary vascular resistance have normal chests (e.g. cases 28, 38 and 43)- Thirdly, it seems unlikely that the spongy lung tissue which intervenes between the heart and the upper sternal region would be a sufficiently good mechanical conductor to cause bony deformity. Fourthly, the elastic recoil of the heart would limit this factor. The cause of the phenomenon must, therefore, be sought in the extra-cardiac forces of the thorax, and these, of course, are related to respiration. The respiratory difficulty which occurs after surgery for V.S.D. has been mentioned already, and is one of the major problems which must be faced in the care of these cases. In some centres (Lillehei, i959) the question is taken so seriously that a pre-operative tracheostomy is performed, the trans-sternal incision has been abandoned in favour of a vertical sternal-splitting one which does not involve the pleural cavities, and mechanical aids to respiration are employed post-operativeIy. It seems logical to ask, therefore, whether or not the deformity in question is related to the mechanical properties of the lungs and the work of breathing. I f this were so, it would adequately explain why the bulging is strictly bilateral, why the anteroposterior diameter of the chest is increased, and why there is often sucking-in of the lower ribs. The problem therefore devolves on the mechanical properties of the lungs in cases of V.S.D. This information is not at present available, partly, no doubt, because it is notoriously difficult to perform pulmonary function studies on children. Any reasoning must, therefore, be based on hypothesis rather than fact. On theoretical grounds, it is possible that two factors should operate in these cases to alter the mechanical properties of the lungs. The first of these is the presence of an increased amount of blood in the lungs. The second is that the pulmonary vasculature is abnormal and contains an increased amount of muscle. The ramifying branches of the pulmonary artery serve as a scaffolding for the pulmonary architecture, and increased stiffness of this scaffolding would lead to changes in the physical properties of the lungs. Separately, these two factors m a y have a variable effect, perhaps none. Thus, the pulmonary blood
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content in atrial septal defect may be very large without making any great difference to pulmonary function. Likewise, some cases of pulmonary hypertension may be associated with relatively normal puhnonary function, as measured by the techniques currently available. Together, however, these two factors could operate to produce changes in the mechanical properties of the lungs, in a manner analogous with such variations in erectile tissue. McIlroy and Apthorp (i958) have studied pulmonary function in patients with pulmonary hypertension and found, in general, a variable reduction in lung compliance, diffusing capacity and ventilation equivalent, with slight increase in inspiratory resistance. Their cases included five with V.S.D., but all these were in the " Eisenmenger group " and none had a pulmonary flow greater than the systemic. In only one of these cases (case I2) was the lung compliance reduced ( i . e . the lungs being " stiffer " than normal). This is in keeping with the observation that a chest deformity is present in only a minority of patients with the " Eisenmenger syndrome " (as defined by Wood, I958), and supports the contention that in these cases the raised pulmonary vascular resistance is present from birth. The finding of a bulging sternum in a patient with t h e " Eisenmenger syndrome " w o u l d suggest that there was at one time a left-to-right shunt. McIlroy and Apthorp (I958) found hyperventilation to be common in pulmonary hypertension. This was not abolished by oxygen, and the stimulus for it is unknown. This would undoubtedly increase the work of breathing. That changes in the properties of the lungs could produce the chest deformity of the V.S.D. is not unlikely. The pigeon-breast, with raised sternum, increased antero-posterior chest diameter, and indrawing of the lower chest wall occurs classically in rickets, being here the response of abnormal bone to normal respiratory forces. (This sternal protuberance was recorded as early as I645 by Whistler.) Naish and Wallis (I948) found, in a study of Harrison's grooves, that they were much commoner in children suffering from asthma than in normal ones, and that their depth depended on how early the disease had started. They also found the grooves to be present in 23 out of 36 cases of congenital heart disease, though the details of diagnosis are not clear. The grooves were also noted frequently in children with a pigeon-breast deformity. A few years earlier, Naish (i945) had recorded marked inspiratory indrawing of the lower intercostal spaces in eight cases of congenital heart disease, seen in infancy, in whom there was no evidence of rickets or of upper respiratory tract infection. This is seen not infrequently in small children with V . S . D . Sheldon (I938) noted the forward bulging of the sternum and costal cartilages in young infants with congenital heart disease, and ascribed it to cardiac hypertrophy. He made the point that there may be collapse of the bases of the lungs due to enlargement of the heart, and noted that in these infants the character of the breathing is often peculiar. It is impossible to deny that this explanation, based entirely on the mechanical effects of an enlarged heart, may be correct. It has the merit of suggesting abnormality of the respiratory apparatus, but is probably an oversimplification. If it were correct that the lungs were stiffer than normal in V.S.D., it would
C H E S T D E F O R M I T I E S IN C O N G E N I T A L
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DISEME
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be expected that the sternal bulging would occur in any case where the essential h~emodynamic requisites are met, viz. increased pulmonary vascular resistance and increased pulmonary blood flow. These factors are present in some cases of patent ductus arteriosus, and indeed the deformity was seen in one such patient. The elevation of the sternum and the insucking of the lower ribs were very marked, as was hyperventilation. This child, aged 3, was operated upon and at the time the surgeon's unsolicited remarks were that " the lungs were stiff." She died soon afterwards. The situation in atrioventricularis communis is similar to that in V.S.D., and the deformity is also seen with this lesion, as it is when a V.S.D. is present together with other lesions, such as patent ductus arteriosus and coarctation of the aorta. In practice, however, the majority of patients with the high sternal protuberance have a V.S.D. That there may be other factors, not at present apparent, is shown by consideration o f case 4, who had severe deformity without much pulmonary hypertension, and cases 37 and 40, who had pulmonary hypertension with increased resistance and flow, but no significant chest deformity. Thus, more work must be done in the study of these deformities before any conclusions become absolute, particularly in relation to pulmonary function and the work of breathing.
Summary The chest deformity associated with the A.S.D. differs clinically and radiologically from that of the V.S.D. In A.S.D. there is a unilateral bulge which lies directly over the right ventricle and is considered to be due directly to the pressure of this enlarged chamber. In V.S.D. there is a bilateral upper sternal protuberance, the antero-posterior diameter of the chest is increased, and there is a tendency for the lower ribs to be drawn in on inspiration. The " V.S.D. type " deformity was found, on a radiological basis, in onehalf of 45 cases of V.S.D. in whom an adequate lateral X-ray of the chest was available, together with cardiac catheterisation data. Thus, the incidence of the " V . S . D . t y p e " deformity in cases of V.S.D. is approximately the same as that of the " A . S . D . t y p e " deformity in cases of A.S.D. In the V.S.D., the deformity, which is similar to a pigeon-breast deformity, was associated in most cases with pulmonary hypertension. It is considered to be much commoner when the pulmonary vascular resistance is raised than when it is not. It occurs in the " Eisenmenger syndrome " in only a minority of cases. It is suggested that the deformity of the V.S.D. may be due to changes in the mechanical properties of the lungs, and that the combination of increased pulmonary vascular resistance and increased pulmonary blood flow increases the stiffness of the lungs. I am much indebted to Dr. S. Gilbert Blount Jr., of Denver, Colorado, for permission to use data from a number ofhis cases; to Drs. Paul Wood and Aubrey Leatham of the National Heart Hospital, London, for like kindness; and to Drs. Peter Kerley and William Evans for their helpful advice.
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REFERENCES LILLEnEI, C. W. (I959) : J. thorac. Surg. (In the press.) MCILRoY, M. B., and APTHORP, G. H. (I958): "Pulmonary Function in Pulmonary Hypertension," Brit. Heart J., 2o, 397. NAISH, A. E. (I945): Arch. Dis. Childh., 2o, I85. NAISH, J., and WALLIS, H. R. E. (I948): " The Significance of Harrison's Grooves," Brit. med. J., *, 54 I. S~I~LDON, W. (I955): "Diseases of Infancy and Childhood," 7th ed., p. 43o. London: J. & A. Churchill. SWAM,H., KORTZ,A. B., DAvIBs, D. H ~ L , and BLOUNT,S. GILBERTJr. (I 959) : "Atrial Septal Defect Secundum," 07. thorac. Surg., S7, 52. TAuss1% H. (I947): " Congenital Malformations of the Heart." (Commonwealth Fund) New York. WHISTLER, D. (I645) : Noted by Naish and Wallis, i948. WooD, P. (i958): " The Eisenmenger Syndrome," Brit. reed. o7., 2, 7oi and 755.