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Reversibility of chronic obstructive lung disease in infants following repair of ventricular septal defect
February 1977
The Journal o f P E D I A T R I C S
187
Reversibility of chronic obstructive lung disease in infants following repair of ventricular septal defect The signs of obstructive lung disease dominated the clinical course of ten infants with ventricular septal dejects and large left-to-right shunts. Airway obstruction in these patients can be attributed (l) to increase in large airway resistance as the result of compression by enlarged pulmonary arteries or cardiac chambers and (2) to increase in small airway" resistance as the restdt of accumulation of peribronchiolar fluid. The rapid regression of the signs of obstructive airway disease following open heart repair of the ventricular septal deject indicates that the lung disease observed in these infants is secondary" to the ventricular septal defect, rather than a primary process. The most effective management in the refractory patient is that of open heart repair of the defect.
Allan J. Hordof, M.D.,* Robert B. Mellins, M.D., Welton M. Gersony, M.D., and Carl N. Sleeg, M.D., N e w York, N. Y.
RAPID
SHALLOW
RESPIRATIONS
and
intercostal
retractions are characteristic features of infants with ventricular septal defects and large left-to-right shunts. These signs are most often attributed to a reduction in lung compliance secondary to engorgement of the pulmonary vascular bed.' It is recognized, however, that some of these patients present primarily with clinical findings of increased airway resistance, i.e., wheezing, hyperinflation, and lobar emphysema.-' The present report summarizes our experience during the past five years with ten infants with ventricular septal defects in whom the signs of obstructive lung disease dominated the clinical picture. The pulmonary problem initially appeared to be out of proportion to the apparent severity of the hemodynamic abnormality and suggested the presence of unrelated pulmonary disease. The rapid and complete regression of the signs of airway obstruction From the Cardiac and Pulmonary Divisions of the Department of Pediatrics, Columbia University College of Physicians and Surgeons, and Babies Hospital, The Childrens Medical and Surgical Center. Supported by National Institutes of Health grants H L 06012, HL 14218, and HL 05389. *Reprint address: Babies Hospital South, Room I02A, 3959 Broadway New York, N Y 10032.
following surgical correction of the ventricular septal defect, however, leads us to the conclusion that obstructive lung disease in these infants was entirely secondary to the cardiovascular hemodynamic abnormalities. SUBJECTS The ten infants who form the basis of this report were admitted to Babies Hospital between one and six months of age. Each of the patients displayed classic signs of congestive heart failure, i.e., tachycardia, tachypnea, Abbreviation used Paco_: arterial carbon dioxide pressure pulmonary rfiles, hepatomegaly, and poor weight gain at some time during their clinical course. The signs of obstructive lung disease, however, were the most impressive and persistent (Table l). Rhonchi and wheezes were present in each of the ten infants. Serial chest roentgenograms showed diffuse hyperinflation in eight infants, lobar emphysema in four, and atelectasis in five. Six of the ten patients had evidence of chronic hypercapnia, with Paco._, values in excess of 45 mm Hg. This is 2 SD above the normal value for infants of this age at this institution.:'
Vol. 90, No. 2, pp. 187-191
!88
Hordof et al.
The Journal of Pediatrics February 1977
60-
Table I, Manifestations o f airway obstruction in ten infants with ventricular septal defect Rhonchi and wheezes Diffuse hyperinflation Lobar emphysema Atelectasis Hypercapnia
10 8 4 5 6
50PoC02
mmHg
I
4030-
20-
p < 0.01
Table II. Preoperative hemodynamic data Mean vascularpressures (mm Hg) Patient (mo)
~
S.M. T.L. B.L. A.M. A.S. B.M. D.M. B.D. I.D. R.M. Mean
65 18 42 4 50 43 5 47 3 40 6 20 8 38 4 33 6 35 2 41.3 6.2
3 2 7 2 2 2 2 2 3 4 2.9
~
/Ao 8 2 9 2 3 2 5 0 4 2 3.7
0.8 0.7 0.8 0.6 0.8 0.6 0.3 0.7 0.5 0.4 0.62
(units~m-') 3.9 2.1 2.3 4.0 3.0 4.0 4.0 3.8 1.8 3.1 3.2
4.0 4.0 2.8 2.8 2.2 1.0 4.0 3.5 3.5 3.1
PA = mean pulmonary artery pressure: LA = mean teft atrial pressure: RA = mean right atrial pressure: PA/Ao = ratio of mean pulmonary artery to systemic artery pressure; t~P/t~s = ratio of pulmonary to systemic blood flow: R = pulmonary vascular resistance.
PREOPERATIVE ASSESSMENT
HEMODYNAMIC
Table II summarizes the hemodynamic data obtained at preoperative cardiac catheterization. At the time of these studies the mean age of the patients was three months, with a range of two to seven months. Mean pulmonary artery pressure was elevated in all but one of the patients. The mean pulmonary artery to systemic artery pressure ratio ranged from 0.3 to 0.8 (mean 0.6). Pulmonary to systemic flow ratios were elevated in all infants; the mean value was 3.2 (range 1.8 to 4.0). Pulmonary vascular resistances were normal or mildly elevated (range of 1 to 4 resistance units). CLINICAL
COURSE
Auscultatory and radiographic evidence of obstructive lung disease persisted throughout the preoperative clinical course in all of the patients. The infants were all treated with a maximal cardiotonic regimen (digoxin, diuretics, and low-salt diet) as well as with chest physiotherapy, without improvements. Early open heart surgical correction of the ventricular septal defect was subsequently carried out in each infant despite the concern that the
I0-
k
0 Pre
Post
Fig. 1, Pre and postoperative Paco 2 values in the six patients whose preoperative course was complicated by chronic hypercapnia. Mean and 1 SD are shown.
pulmonary disease could be a primary process. The mean age at surgery was six months; the range was three to 12 months. Surgical repair was carried out using cardiopulmonary bypass with normothermia and high blood flow rates. There were no operative deaths. The postoperative course was uneventful in four of the patients. Two infants had significant atelectasis in the early postoperative period which resolved within seven days, concomitant with the institution of vigorous chest physiotherapy. In another patient recurrent left upper lobe and right middle lobe atelectasis persisted for more than two months postoperatively, but subsequently cleared completely. In one patient elevation of P a c o persisted during the first postoperative week and then returned to normal values. Two patients had residual ventricular septal defects that resulted in postoperative congestive heart failure. One of these infants, who required a vigorous cardiotonic regimen postoperatively, was discharged after the fortieth postoperative day with digoxin and diuretic therapy; he improved gradually. Postoperative cardiac catheterization revealed only a small residual ventricular septal defect ( 0 p / 0 s = 1.5/1) and normal pulmonary artery pressure. The other child with a residual defect required repeat open heart surgery, because o f chronic heart failure and persistent symptoms of obstructive lung disease. Following repeat surgical repair of the defect, there was gradual but complete clearing of all abnormalities. Fig. 1 demonstrates the mean pre and postoperative Paco, values in the six patients with chronic hypercapnia. During the first postoperative month there was a significant reduction in the P a c o from a mean value of 50 _+ 4 mm Hg to 36 + 3 mm Hg (p < 0.01).
Volume 90 Number 2
Chronic obstructive hmg disease after repair of VSD
18 9
S.
,)
Fig. 2. A, Preoperative roentgenogram demonstrating hyperinflation (low diaphragms) and prominent opacification in the right upper lobe. B, Postoperative roentgenogram demonstrating clearing of the right upper lobe opacity. The diffuse hyperinflation seen preoperatively is no longer present.
Figs. 2 and 3 show representative pre and postoperative chest roentgenograms. In each instance there was a regression of the roentgenographic evidence of obstructive lung disease. In Fig. 2, A, the preoperative roentgenogram demonstrates diffuse hyperinflation with low diaphragms and right upper lobe atelectasis. Postoperatively (Fig. 2, B) the lungs show appreciable regression of the obstructive lung disease. Fig. 3, A, shows a preoperative roentgenogram in one of the patients whose ventricular septal defect was complicated by hyperinflation of the left upper lobe. The postoperative chest roentgenogram (Fig. 3, B) shows dramatic resolution of the hyperinflated left upper lobe. DISCUSSION The ten infants who form the basis for this report differ from the usual patient with a ventricular septal defect and left-to-right shunt in that the signs of increased airway obstruction dominated the clinical picture and were more prominent than the other more conventional manifestations of heart failure. There are several possible mechanisms to explain the findings of increased airway resistance in these patients: (1) increase in large airway resistance as the result of compression by enlarged pulmonary arteries and cardiac chambers, (2) increase in small airway resistance as a result of accumulation of peribronchiolar fluid, (3) edema of the bronchial wall secondary to
increased systemic and pulmonary venous pressure, and (4) reflex broncboconstriction. Large airways may be compressed by tense pulmonary arteries or enlarged cardiac chambers, particularly the left atrium. Postmortem demonstration of compression of the left main bronchus by the major pulmonary vessels and the left atrium has been provided? ~' These investigators studied specimens from infants with congenital heart disease and either increased pulmonary vascular pressure or flow or a combination of both. Significant morbidity and mortality has been ascribed to massive atelectasis secondary to large airway compression. ",~ When bronchial obstruction is partial, segmental or lobar emphysema may occur, as wag seen in our patients. Turbulent flow in the partially obstructed bronchi would account for the presence of the persistent wheezes and rhonchi heard in these patients. The indentations produced in the large airways by the engorged pulmonary vessels may take time to regress even after the surgical closure of the ventricular septal defect and the elimination of the large pulmonary blood flow and pressure. The delay in regression of the anatomic obstruction in these airways may account for some of the persistent pulmonary problems in the postoperative period seen in these patients. An increase in small airway resistance in infants with large ventricular septal defects may result from small airway narrowing by peribronchiolar collections of fluid.
190
H o r d o f et al.
The Journal of Pediatrits February It~77
Fig, 3- A, Preoperative roentgenogram demonstrating emphysema of the left upper lobe (outlined by arrows). The generalized hyperinflation masks the presence of cardiomegaly and pulmonary overcirculation. B, Postoperatively the emphysema of the left upper lobe has resolved
Obstruction may occur either as a result of direct compression or because the presence of edema surrounding the bronchioles reduces the normal tethering or distending action of the lungs on small airways. Infants with ventricular septal defects and large left-toright shunts may have pulmonary edema from at least two mechanisms; (1) increased hydrostatic pressure in the fluid exchanging vessels, and (2) decreased perivascular pressures around the fluid exchanging vessels: this is a consequence of decreased (more negative) intrathoracic pressures resulting from increased airway resistance or decreased lung compliance during inspiration. The intercostal retractions during inspiration in these infants are an obvious manifestation of this phenomenon. Although the peripheral or small airways contribute only a small proportion of the total airway resistance in the adult," there is evidence indicating that the small airways contribute a relatively ~arger proportion of the total airway resistance in infants." Thus, the diffuse hyperinflation seen in the majority of our patients may be secondary to an increase in small airway resistance as a result of peribronchiolar edema. This mechanism may also account for the elevation of Paco 2 seen in the majority of the present group of patients and also reported in other infants with pulmonary engorgement and congestive heart failure. ''> This is in contrast with the decrease in P a c o often seen in adults with left heart
failure.". "-' There is evidence that pulmonary engorge+ ment and edema result in increased peripheral airway resistance and premature airway closureY: These findings, which have been better documented in the adult, are probably even more important factors in the infant in whom the small airways contribute a greater proportion of the total airway resistance. Edema of the bronchial wall was considered as a possible cause of increased airway resistance in these patients. The observation that the systemic and pulmonary venous pressures were not elevated in the majority of infants, however, makes this a less likely mechanism. Although theoretically high systemic venous pressures could impede lymphatic drainage from the lung, recent work" suggests that the lymphatics are capable of pumping effectively against elevated pressures. The extent to which reflex bronchoconstriction is responsible for the increased airway resistance in these patients remains unanswered.':' Patients with obstructive lung disease associated wilh ventricular septal defect may prove to be difficult diagnostic and management problems. Signs of obstructive lung disease may not be recognized as manifestations of heart failure secondary to large left-to-right shunts. Furthermore. in the presence of pulmonary hyperinflation, heart size, and pulmonary vascularity tend to be underestimated by conventional roentgenographic
Volume 90 Number 2
techniques. The recognition that the lung disease is indeed secondary to the hemodynamic alterations of the underlying congenital heart defect is crucial to the successful m a n a g e m e n t of these patients. If the signs of airway obstruction are appreciable and persist after a vigorous pulmonary and cardiotonic regimen has been instituted, surgical closure of the ventricular septal defect should be performed. With current techniques for open heart surgery and postoperative management of infants, repair of the ventricular septal defect can be carried out at relatively low risk.
Chronic obstructive lung disease after repair of VSD
7. 8.
9.
10.
REFERENCES
1. Howlett G: Lung mechanics in normal infants and infants with congenital heart disease, Arch Dis Child 47:707, 1972. 2. Rudolph AM: Diagnosis and treatment: Respiratory distress and cardiac disease in infancy, Pediatrics 35:999, 1965. 3. Dell R, Albert MS, and Winters RW: Acid base equilibrium of blood in normal infants, Pediatrics 3"7:728, 1966. 4. Edwards JE, and Burchell HB: Effects of pulmonary hypertension on the tracheobronchial tree, Dis Chest 38:272, 1960. 5. Stanger P, Lucas RV Jr, and Edwards JE: Anatomic factors causing respiratory distress in acyanotic congenital cardiac disease, Pediatrics 43:760, 1969. 6. Rivkin LM, Read RC, Lillehei CW, and Varco RL: Massive
11.
12.
13.
14.
15.
19 1
atelectasis of the left lung in children with congenital heart disease, J Thorac Surg 34:116, 1957. Bryk D" Atelectasis, emphysema and heart diseases, Am J Dis Child 110:100, 1965. Hogg JC, Macklem PT, and Thurlbeck MB: Site and nature of airway obstruction in chronic obstructive lung disease, N Engl J Med 278:1355, 1968. Hogg JC, Williams J, Richardson JB, Macklem PT, and Thurlbeck WM: Age as a factor in the distribution of lower airway conductance and in the pathologic anatomy of obstructive lung disease, N Engl J Med 282:1283, 1970. Talner NS, Sanyal SK, Halloran KH, Gardner TH, and Ordway NK: Congestive heart failure in infancy. I. Abnormalities in blood gases and acid-base equilibrium, Pediatrics' 35:20, 1965. Squires RD, Singer RB, Moflitt GR Jr, and Elkinson JR: The distribution of body fluids in congestive heart failure. II. Abnormalities in serum electrolytes concentration and acid-base equilibrium, Circulation 4:699, 1951. Cosby RS, Stowell EC, Hartwig WR, and Mayo M: Pulmonary function in left ventricular failure including cardiac asthma, Circulation 15:492, 1957. Milic-Emili J, and Ruff F: Effects of pulmonary congestion and edema on the small airways, Bull Physiopathol Respir 7:1181, 1971. Pang LM, Mellins RB, and Rodriguez-Martinez F: Effect of acute lymphatic obstruction on fluid accumulation in the chest in dogs, J Appl Physiol 39:985, 1975. Nadel JA: Aerosol effects on smooth muscle and airway visualization technique, Arch Intern Med 131:83, 1973.
The Journal o f P E D I A T R I C S
187
Reversibility of chronic obstructive lung disease in infants following repair of ventricular septal defect The signs of obstructive lung disease dominated the clinical course of ten infants with ventricular septal dejects and large left-to-right shunts. Airway obstruction in these patients can be attributed (l) to increase in large airway resistance as the result of compression by enlarged pulmonary arteries or cardiac chambers and (2) to increase in small airway" resistance as the restdt of accumulation of peribronchiolar fluid. The rapid regression of the signs of obstructive airway disease following open heart repair of the ventricular septal deject indicates that the lung disease observed in these infants is secondary" to the ventricular septal defect, rather than a primary process. The most effective management in the refractory patient is that of open heart repair of the defect.
Allan J. Hordof, M.D.,* Robert B. Mellins, M.D., Welton M. Gersony, M.D., and Carl N. Sleeg, M.D., N e w York, N. Y.
RAPID
SHALLOW
RESPIRATIONS
and
intercostal
retractions are characteristic features of infants with ventricular septal defects and large left-to-right shunts. These signs are most often attributed to a reduction in lung compliance secondary to engorgement of the pulmonary vascular bed.' It is recognized, however, that some of these patients present primarily with clinical findings of increased airway resistance, i.e., wheezing, hyperinflation, and lobar emphysema.-' The present report summarizes our experience during the past five years with ten infants with ventricular septal defects in whom the signs of obstructive lung disease dominated the clinical picture. The pulmonary problem initially appeared to be out of proportion to the apparent severity of the hemodynamic abnormality and suggested the presence of unrelated pulmonary disease. The rapid and complete regression of the signs of airway obstruction From the Cardiac and Pulmonary Divisions of the Department of Pediatrics, Columbia University College of Physicians and Surgeons, and Babies Hospital, The Childrens Medical and Surgical Center. Supported by National Institutes of Health grants H L 06012, HL 14218, and HL 05389. *Reprint address: Babies Hospital South, Room I02A, 3959 Broadway New York, N Y 10032.
following surgical correction of the ventricular septal defect, however, leads us to the conclusion that obstructive lung disease in these infants was entirely secondary to the cardiovascular hemodynamic abnormalities. SUBJECTS The ten infants who form the basis of this report were admitted to Babies Hospital between one and six months of age. Each of the patients displayed classic signs of congestive heart failure, i.e., tachycardia, tachypnea, Abbreviation used Paco_: arterial carbon dioxide pressure pulmonary rfiles, hepatomegaly, and poor weight gain at some time during their clinical course. The signs of obstructive lung disease, however, were the most impressive and persistent (Table l). Rhonchi and wheezes were present in each of the ten infants. Serial chest roentgenograms showed diffuse hyperinflation in eight infants, lobar emphysema in four, and atelectasis in five. Six of the ten patients had evidence of chronic hypercapnia, with Paco._, values in excess of 45 mm Hg. This is 2 SD above the normal value for infants of this age at this institution.:'
Vol. 90, No. 2, pp. 187-191
!88
Hordof et al.
The Journal of Pediatrics February 1977
60-
Table I, Manifestations o f airway obstruction in ten infants with ventricular septal defect Rhonchi and wheezes Diffuse hyperinflation Lobar emphysema Atelectasis Hypercapnia
10 8 4 5 6
50PoC02
mmHg
I
4030-
20-
p < 0.01
Table II. Preoperative hemodynamic data Mean vascularpressures (mm Hg) Patient (mo)
~
S.M. T.L. B.L. A.M. A.S. B.M. D.M. B.D. I.D. R.M. Mean
65 18 42 4 50 43 5 47 3 40 6 20 8 38 4 33 6 35 2 41.3 6.2
3 2 7 2 2 2 2 2 3 4 2.9
~
/Ao 8 2 9 2 3 2 5 0 4 2 3.7
0.8 0.7 0.8 0.6 0.8 0.6 0.3 0.7 0.5 0.4 0.62
(units~m-') 3.9 2.1 2.3 4.0 3.0 4.0 4.0 3.8 1.8 3.1 3.2
4.0 4.0 2.8 2.8 2.2 1.0 4.0 3.5 3.5 3.1
PA = mean pulmonary artery pressure: LA = mean teft atrial pressure: RA = mean right atrial pressure: PA/Ao = ratio of mean pulmonary artery to systemic artery pressure; t~P/t~s = ratio of pulmonary to systemic blood flow: R = pulmonary vascular resistance.
PREOPERATIVE ASSESSMENT
HEMODYNAMIC
Table II summarizes the hemodynamic data obtained at preoperative cardiac catheterization. At the time of these studies the mean age of the patients was three months, with a range of two to seven months. Mean pulmonary artery pressure was elevated in all but one of the patients. The mean pulmonary artery to systemic artery pressure ratio ranged from 0.3 to 0.8 (mean 0.6). Pulmonary to systemic flow ratios were elevated in all infants; the mean value was 3.2 (range 1.8 to 4.0). Pulmonary vascular resistances were normal or mildly elevated (range of 1 to 4 resistance units). CLINICAL
COURSE
Auscultatory and radiographic evidence of obstructive lung disease persisted throughout the preoperative clinical course in all of the patients. The infants were all treated with a maximal cardiotonic regimen (digoxin, diuretics, and low-salt diet) as well as with chest physiotherapy, without improvements. Early open heart surgical correction of the ventricular septal defect was subsequently carried out in each infant despite the concern that the
I0-
k
0 Pre
Post
Fig. 1, Pre and postoperative Paco 2 values in the six patients whose preoperative course was complicated by chronic hypercapnia. Mean and 1 SD are shown.
pulmonary disease could be a primary process. The mean age at surgery was six months; the range was three to 12 months. Surgical repair was carried out using cardiopulmonary bypass with normothermia and high blood flow rates. There were no operative deaths. The postoperative course was uneventful in four of the patients. Two infants had significant atelectasis in the early postoperative period which resolved within seven days, concomitant with the institution of vigorous chest physiotherapy. In another patient recurrent left upper lobe and right middle lobe atelectasis persisted for more than two months postoperatively, but subsequently cleared completely. In one patient elevation of P a c o persisted during the first postoperative week and then returned to normal values. Two patients had residual ventricular septal defects that resulted in postoperative congestive heart failure. One of these infants, who required a vigorous cardiotonic regimen postoperatively, was discharged after the fortieth postoperative day with digoxin and diuretic therapy; he improved gradually. Postoperative cardiac catheterization revealed only a small residual ventricular septal defect ( 0 p / 0 s = 1.5/1) and normal pulmonary artery pressure. The other child with a residual defect required repeat open heart surgery, because o f chronic heart failure and persistent symptoms of obstructive lung disease. Following repeat surgical repair of the defect, there was gradual but complete clearing of all abnormalities. Fig. 1 demonstrates the mean pre and postoperative Paco, values in the six patients with chronic hypercapnia. During the first postoperative month there was a significant reduction in the P a c o from a mean value of 50 _+ 4 mm Hg to 36 + 3 mm Hg (p < 0.01).
Volume 90 Number 2
Chronic obstructive hmg disease after repair of VSD
18 9
S.
,)
Fig. 2. A, Preoperative roentgenogram demonstrating hyperinflation (low diaphragms) and prominent opacification in the right upper lobe. B, Postoperative roentgenogram demonstrating clearing of the right upper lobe opacity. The diffuse hyperinflation seen preoperatively is no longer present.
Figs. 2 and 3 show representative pre and postoperative chest roentgenograms. In each instance there was a regression of the roentgenographic evidence of obstructive lung disease. In Fig. 2, A, the preoperative roentgenogram demonstrates diffuse hyperinflation with low diaphragms and right upper lobe atelectasis. Postoperatively (Fig. 2, B) the lungs show appreciable regression of the obstructive lung disease. Fig. 3, A, shows a preoperative roentgenogram in one of the patients whose ventricular septal defect was complicated by hyperinflation of the left upper lobe. The postoperative chest roentgenogram (Fig. 3, B) shows dramatic resolution of the hyperinflated left upper lobe. DISCUSSION The ten infants who form the basis for this report differ from the usual patient with a ventricular septal defect and left-to-right shunt in that the signs of increased airway obstruction dominated the clinical picture and were more prominent than the other more conventional manifestations of heart failure. There are several possible mechanisms to explain the findings of increased airway resistance in these patients: (1) increase in large airway resistance as the result of compression by enlarged pulmonary arteries and cardiac chambers, (2) increase in small airway resistance as a result of accumulation of peribronchiolar fluid, (3) edema of the bronchial wall secondary to
increased systemic and pulmonary venous pressure, and (4) reflex broncboconstriction. Large airways may be compressed by tense pulmonary arteries or enlarged cardiac chambers, particularly the left atrium. Postmortem demonstration of compression of the left main bronchus by the major pulmonary vessels and the left atrium has been provided? ~' These investigators studied specimens from infants with congenital heart disease and either increased pulmonary vascular pressure or flow or a combination of both. Significant morbidity and mortality has been ascribed to massive atelectasis secondary to large airway compression. ",~ When bronchial obstruction is partial, segmental or lobar emphysema may occur, as wag seen in our patients. Turbulent flow in the partially obstructed bronchi would account for the presence of the persistent wheezes and rhonchi heard in these patients. The indentations produced in the large airways by the engorged pulmonary vessels may take time to regress even after the surgical closure of the ventricular septal defect and the elimination of the large pulmonary blood flow and pressure. The delay in regression of the anatomic obstruction in these airways may account for some of the persistent pulmonary problems in the postoperative period seen in these patients. An increase in small airway resistance in infants with large ventricular septal defects may result from small airway narrowing by peribronchiolar collections of fluid.
190
H o r d o f et al.
The Journal of Pediatrits February It~77
Fig, 3- A, Preoperative roentgenogram demonstrating emphysema of the left upper lobe (outlined by arrows). The generalized hyperinflation masks the presence of cardiomegaly and pulmonary overcirculation. B, Postoperatively the emphysema of the left upper lobe has resolved
Obstruction may occur either as a result of direct compression or because the presence of edema surrounding the bronchioles reduces the normal tethering or distending action of the lungs on small airways. Infants with ventricular septal defects and large left-toright shunts may have pulmonary edema from at least two mechanisms; (1) increased hydrostatic pressure in the fluid exchanging vessels, and (2) decreased perivascular pressures around the fluid exchanging vessels: this is a consequence of decreased (more negative) intrathoracic pressures resulting from increased airway resistance or decreased lung compliance during inspiration. The intercostal retractions during inspiration in these infants are an obvious manifestation of this phenomenon. Although the peripheral or small airways contribute only a small proportion of the total airway resistance in the adult," there is evidence indicating that the small airways contribute a relatively ~arger proportion of the total airway resistance in infants." Thus, the diffuse hyperinflation seen in the majority of our patients may be secondary to an increase in small airway resistance as a result of peribronchiolar edema. This mechanism may also account for the elevation of Paco 2 seen in the majority of the present group of patients and also reported in other infants with pulmonary engorgement and congestive heart failure. ''> This is in contrast with the decrease in P a c o often seen in adults with left heart
failure.". "-' There is evidence that pulmonary engorge+ ment and edema result in increased peripheral airway resistance and premature airway closureY: These findings, which have been better documented in the adult, are probably even more important factors in the infant in whom the small airways contribute a greater proportion of the total airway resistance. Edema of the bronchial wall was considered as a possible cause of increased airway resistance in these patients. The observation that the systemic and pulmonary venous pressures were not elevated in the majority of infants, however, makes this a less likely mechanism. Although theoretically high systemic venous pressures could impede lymphatic drainage from the lung, recent work" suggests that the lymphatics are capable of pumping effectively against elevated pressures. The extent to which reflex bronchoconstriction is responsible for the increased airway resistance in these patients remains unanswered.':' Patients with obstructive lung disease associated wilh ventricular septal defect may prove to be difficult diagnostic and management problems. Signs of obstructive lung disease may not be recognized as manifestations of heart failure secondary to large left-to-right shunts. Furthermore. in the presence of pulmonary hyperinflation, heart size, and pulmonary vascularity tend to be underestimated by conventional roentgenographic
Volume 90 Number 2
techniques. The recognition that the lung disease is indeed secondary to the hemodynamic alterations of the underlying congenital heart defect is crucial to the successful m a n a g e m e n t of these patients. If the signs of airway obstruction are appreciable and persist after a vigorous pulmonary and cardiotonic regimen has been instituted, surgical closure of the ventricular septal defect should be performed. With current techniques for open heart surgery and postoperative management of infants, repair of the ventricular septal defect can be carried out at relatively low risk.
Chronic obstructive lung disease after repair of VSD
7. 8.
9.
10.
REFERENCES
1. Howlett G: Lung mechanics in normal infants and infants with congenital heart disease, Arch Dis Child 47:707, 1972. 2. Rudolph AM: Diagnosis and treatment: Respiratory distress and cardiac disease in infancy, Pediatrics 35:999, 1965. 3. Dell R, Albert MS, and Winters RW: Acid base equilibrium of blood in normal infants, Pediatrics 3"7:728, 1966. 4. Edwards JE, and Burchell HB: Effects of pulmonary hypertension on the tracheobronchial tree, Dis Chest 38:272, 1960. 5. Stanger P, Lucas RV Jr, and Edwards JE: Anatomic factors causing respiratory distress in acyanotic congenital cardiac disease, Pediatrics 43:760, 1969. 6. Rivkin LM, Read RC, Lillehei CW, and Varco RL: Massive
11.
12.
13.
14.
15.
19 1
atelectasis of the left lung in children with congenital heart disease, J Thorac Surg 34:116, 1957. Bryk D" Atelectasis, emphysema and heart diseases, Am J Dis Child 110:100, 1965. Hogg JC, Macklem PT, and Thurlbeck MB: Site and nature of airway obstruction in chronic obstructive lung disease, N Engl J Med 278:1355, 1968. Hogg JC, Williams J, Richardson JB, Macklem PT, and Thurlbeck WM: Age as a factor in the distribution of lower airway conductance and in the pathologic anatomy of obstructive lung disease, N Engl J Med 282:1283, 1970. Talner NS, Sanyal SK, Halloran KH, Gardner TH, and Ordway NK: Congestive heart failure in infancy. I. Abnormalities in blood gases and acid-base equilibrium, Pediatrics' 35:20, 1965. Squires RD, Singer RB, Moflitt GR Jr, and Elkinson JR: The distribution of body fluids in congestive heart failure. II. Abnormalities in serum electrolytes concentration and acid-base equilibrium, Circulation 4:699, 1951. Cosby RS, Stowell EC, Hartwig WR, and Mayo M: Pulmonary function in left ventricular failure including cardiac asthma, Circulation 15:492, 1957. Milic-Emili J, and Ruff F: Effects of pulmonary congestion and edema on the small airways, Bull Physiopathol Respir 7:1181, 1971. Pang LM, Mellins RB, and Rodriguez-Martinez F: Effect of acute lymphatic obstruction on fluid accumulation in the chest in dogs, J Appl Physiol 39:985, 1975. Nadel JA: Aerosol effects on smooth muscle and airway visualization technique, Arch Intern Med 131:83, 1973.