- Email: [email protected]
The pulmonary artery after debanding
The pulmonary artery after debanding A. R. C. Dobell, M.D., D. A. Murphy, M.D. (by invitation), N. L. Poirier, M.D. (by invitation), and J. E. Gibbons, M.D. (by invitation), Montreal, Quebec, Canada
Iingn hasthe been past decade, pulmonary artery bandthe preferred surgical treatment for infants with cardiac failure due to large left-to-right shunts at the ventricular level. Infants with this type of palliation undergo closure of the defect and removal of the pulmonary band a few years later. The alternative to this two-stage technique is primary closure of the defect in infancy, and the choice between these two options is influenced primarily by the confidence and experience of each surgical team in performing intracardiac surgery in small infants. Four of our patients who had undergone the two-stage procedure later required another intracardiac operation to close a residual shunt. At this time impressive constriction of the pulmonary artery at the previous band-site was noted, and pulmonary artery reconstruction was required along with the shunt closure. These experiences prompted us to recall children who had had the two-stage procedure for late hemodynamic studies. These studies, together with pertinent operative findings in the 4 cases mentioned above, form the basis of this report. From the Departments of Cardiology and Cardiovascular Surgery, The Montreal Children's Hospital and McGill University. Read at the Fifty-second Annual Meeting of The American Association for Thoracic Surgery, Los Angeles, Calif., May I, 2, and 3, 1972.
32
Patients and results
Seventy-two infants and small children had pulmonary arteries banding between 1960 and 1972. Half of this group had isolated high-flow ventricular septal defects (VSD), and the remainder had more complex abnormalities. Sixty-six of these patients were under 1 year of age, and 56 of these were less than 6 months old. Thirty-four children later underwent pulmonary artery debanding and defect repair. Of the 29 long-term survivors, 18 have been restudied and will henceforth be referred to as the Restudy Group. This group includes children suspected of having a residual defect and those who lived close enough to this center to return conveniently for hemodynamic evaluation. Except for the fact that the Restudy Group contained those children suspected of having residual VSD, it was representative of the entire group of patients with pulmonary artery debanding. For example, the mean ages for banding and debanding in the larger group were 5 and 51 months, while in the Restudy Group these ages were 5 and 53 months. The late evaluation in the latter patients was done at an average age of 100 months with a range from 30 to 150 months. The present report is concerned with the state of the reconstructed pulmonary artery at the time of restudy, an average of 4 years after debanding. The data consist of pres-
Volume 65 Number 1 Jonuory, 1973
sure gradients and angiographic measurements of pulmonary artery size. Data on residual left-to-right shunts are presented since they influence the interpretation of the pressure data. At restudy, right heart catheterizations were performed, and cineangiograms in two planes were made. Pulmonary artery measurements were taken from the lateral angiogram after injection of contrast material into the right ventricle. Pulmonary artery diameter at the site of debanding was related to its diameter just above the annulus and expressed as a ratio. The results are shown in Tables I and II. Representative angiograms, which demonstrate the lowest and highest pulmonary artery-to-annulus ratios as well as the ratio close to the mean for the entire group, are shown in Figs. 1,2, and 3. The tables indicate a modest band-site gradient ranging from 6 to 48 mm. Hg in those patients with an intact ventricular septum and from 18 to 72 mm. Hg in those with a residual VSD. Similarly, the reduction in pulmonary artery diameter compared to that in normal subjects (Table II) is modest, with the diameter about 75 per cent of normal size. Four of these patients were reoperated upon to close the residual VSD and to enlarge the strictured pulmonary artery. The observations made during these reoperations provide additional data for this study and are shown in Table III. In 3 of the 4 there was significant restenosis at the bandsite, necessitating plastic repairs. The cicatrization was extremely pronounced in 1 case, and stenosis will likely recur in the future despite excision of the anterior half of the stricture and reconstruction with interrupted sutures. Although the excised segment was 1 em. wide, fibrosis remained in the margins. Discussion The hemodynamic studies which we undertook some time after debanding show a tendency to moderate recurrence of stenosis at the band-site. The figures are
Pulmonary artery after debanding
33
Table I. Right ventricular and pulmonary artery pressures 4 years after debanding
VSD closed (12 patients) Mean Range
40 28-60
20 12-40
19 6-48
Residual VSD (6 patients) Mean Range
76 60-96
31 22-42
45 18-72
Legend: RV, Right ventricle. PA, Pulmonary artery. VSD, Ventricular septal defect.
Table II. Pulmonary artery-annulus ratio Mean
Range
Normal subject Banded PA
1.07 0.40
1.02-1.18 0.31-0.48
Debanded Patch repair Dilatation only
0.82 0.70
0.71-0.97 0.56-0.90
Legend: PA, Pulmonary artery.
by no means alarming and may even be considered reassuring in view of the moderate gradients at rest. On the other hand, the children are still growing, and none of them has begun the adolescent growth spurt which will result in much larger pressure gradients if the strictures are fixed and do not grow. That this is a genuine matter for concern is suggested from our observations at reoperation on 4 of these children, in whom fibrosis at the band-site tended to be impressive. Technical modifications in both banding and debanding might reduce the stricture at the band-site. In our patients, either umbilical tape or Teflon-covered tape was used for banding. Although the latter came off more easily, we always found dense fibrosis beneath the tape where the pulmonary artery wall had been replaced by scar tissue. The specific fabric probably is not too important since most of the fibrosis is caused by the physical presence of the band, which creates pressure necrosis beneath it and extreme turbulence within the pulmonary
The Journal of
34
Dobell et al.
Fig. 1. Lateral angiogram on a 5-year-old girl 10 months after debanding and dilatation of pulmonary artery stricture. Right ventricular systolic pressure was 96 mm. Hg, distal pulmonary artery pre ssure was 38 mm. Hg, the ventr icular septal defect was open , and the pulmonary artery-annulus ratio was 0.56.
Fig. 2. Lateral angiogram on a 7-year-old girl 4 years after closure of the ventricular septal defect and dilatation of the pulmonary artery after band removal. Right ventricular systolic pressure was 50 rnm. Hg, distal pulmonary artery pressure was 40 mrn. Hg, and the pulmon ary artery-annulus ratio was 0.90.
artery. The progressive development of the arterial lesion of banding has been thoroughly presented by Berry.' Umbilical tape is not always completely removable, and thus a tape that resists invasion is preferable. The Teflon-covered band that we have used is unnecessaril y wide. In this regard, the experience at the Hospital for Sick Children, Great Ormond Street, is of interest. 6 Sur-
Thorac ic a nd Cardiovascular Surgery
Fig. 3. Lateral angiogram on a 9-year-old boy 6 years after debanding and pericardial patch repair of the pulmonary artery . Right ventr icular systolic pressure was 60 mm. Hg, distal pulmonary artery pressure was 25 mm. Hg, and proximal pulmonary artery pressure was 50 mm. Hg,
geons there claim satisfaction with narrow bands of silk ligatures, 1.2 mm. in diameter. A heavy synthetic ligature would be more easily removed. It seems important to us to reduce the length of scar to a minimum by using narrow bands. Another consideration in limiting the amount of stricture is reduction of the interval between banding and debanding. Regrettably, the arterial lesion of banding can be well developed by 14 weeks,1 but late complications such as migration into the pulmonary artery' and calcification1 suggest that debanding should be done electively at an early date. Another interesting lesion related to banding is acquired pulmonic stenosis as suggested by Hunt and his associates.' They noticed pulmonary valve thickening and commissural fusion when the band was placed within 15 mm. of the pulmonary valve annulus . We too have noticed this lesion and agree that it is probably secondary to the trauma of the valve cusps striking the narrowed pulmonary artery. We suspect that turbulence alone contributes to the valve fibrosis. Although pulmonary valve insufficiency has not been detected clinically, pressure tracings suggest its presence in a number of our patients. " Our current position on banding versus
Volume 65
Pulmonary artery after debanding
Number 1
35
Jonuory, 1973
Table III. Data on 4 patients who had second intracardiac operations Time since deCase banding (mo.) No. 1* 2 3 4
10 20 19 15
Systolic pressure RV
96 76 81 96
I PA 38 20 24
PA-
annulus ratio
0.56 0.60 0.78 0.63
Size of residual VSD (mm.)
I.D. of PA at band-site (mm.)
Repair of PAt
PA at operation
13 12 14
None Patch Patch Excision of anterior scar
Posterior ridge Fibrous ring Dense scar
10
3 10 5
Legend: RV, Right ventricle. PA, Pulmonary artery. VSD, Ventricular septal defect. 1.0., Inner diameter.
'This patient had double-outlet right ventricle. tThe repair was done at the second intracardiac operation.
closure of the defect in infancy is to follow the latter course- in most instances and reserve banding for the more complex lesions such as double-outlet right ventricle. Since 1960 we have closed the VSD primarily in 14 very ill infants with one death. Banding alone has had a higher mortality rate in our experience with VSD, and it is appreciably higher with more complex lesions. Our initial interest in banding was not based on any supposed intolerance of infants to cardiopulmonary bypass, because we have always found that babies withstand bypass as well as if not better than older children. However, we were concerned about the lack of fibrous tissue in the ventricular septum and feared a higher rate of residual VSD than in older children. It is obvious from the small series presented herein that the two-stage approach in our hands has not solved this problem.
only after serious consideration of the two other options, namely, supportive medical therapy with later defect closure and defect closure in infancy. Banding will still be the preferred treatment in certain infants. A narrow band hopefully will reduce the longitudinal extension of fibrosis in the pulmonary artery. REFERENCES
2
3
4
Summary and conclusions
The application of a band to the main pulmonary artery followed by its removal sometime later leads to a permanent fibrous stricture at the band-site. Our studies on 18 children an average of 4 years after band removal indicate mild-to-moderate obstruction in most patients as judged by pressure gradients and angiography. We reoperated upon 4 patients to close residual defects and were impressed with the marked fibrosis at the band-site in this group. Pulmonary artery banding should be done
5
6
Berry, C. L.: Changes in the Wall of the Pulmonary Artery After Banding, J. Pathol. 99: 29, 1969. Ching, E., DuShane, J. W., McGoon, D. C., and Danielson, G. K.: Total Correction of Ventricular Septal Defect in Infancy Using Extracorporeal Circulation, Ann. Thorac. Surg. 12: 1, 1971. Ebert, P. A., Cane nt, R. V., Jr., Spach, M. S., and Sabiston, D. C., Jr.: Late Cardiodynamics Following Correction of Ventricular Septal Defects With Previous Pulmonary Artery Banding, J. THORAC. CARDIOVASC. SURG. 60: 516, 1970. Hunt, C. E., Formanek, G., Levine, M. A., Castaneda, A., and Moller, J. H.: Banding of the Pulmonary Artery: Results in 111 Children, Circulation 43: 395, 1971. Rohmer, 1., Brom, A. G., and Nauta, J.: Bands Inside the Pulmonary Artery: A Complication of the Dammann-Muller Procedure, Ann. Thorac. Surg. 3: 449, 1967. Stark, J., Aberdeen, E., Waterston, D. 1., Bonham-Carter, R. E., and Tynan, M.: Pulmonary Artery Constriction (Banding): A Report of 146 Cases, Surgery 65: 808, 1969.
Discussion DR. A. ROBERT CORDELL Winston-Salem, N. C.
We are again indebted to Dr. Dobell and his group for this very detailed study of a group of
The Journal of
36
Dobell et al.
Thoracic and Cardiovascular Surgery
patients which many of us have found to be extremely interesting although difficult to treat. Our experience with debanding has been more limited and has included 8 patients thus far. However, we look with concern upon 35 other patients in our institution who await debanding and will undoubtedly require this operation. One of these 8 patients died because of intense scarring and thinning, such as that mentioned by Dr. Dobell. The band in this patient had migrated to the bifurcation of the pulmonary artery and had produced intense periarterial fibrosis, scarring, and thinning of both pulmonary artery trunks. Repair was therefore extremely difficult. [Slide] Adequate relief of the gradient at this portion in the pulmonary trunk was not attained, and examination at autopsy suggested that the insertion of a bifurcated homograft might have restored relatively normal caliber of each pulmonary trunk beyond the bifurcation of the common pulmonary artery. It is significant that thus far in our experience every pulmonary artery has shown marked thinning, severe stenosis, and marked scarring when approached for definitive correction. In all of these patients, either cotton or Dacron was used.
[Slide] A review of materials used in pulmonary banding suggests that Dacron covered by silicone rubber produces less scarring than other materials while at the same time giving adequate strength. The minimal tissue reaction is being investigated currently in the laboratory. We think the luminal caliber of 12 mm. is necessary in order to keep the gradient as low as possible in these patients. Therefore, we would like to emphasize that pulmonary banding should be limited to the few desperately ill infants which are not candidates for direct repair. DR. A. R. C. DOBELL (Closing) I appreciate Dr. Cordell's remarks, and I think we are in total agreement. Perhaps I can reiterate that I don't think the solution will be in choosing some other type of band material. Banding always produces a pulmonary artery lesion, and the surgeon must try to restrict the length of this stricture, with a view, possibly, to excising it at the time of correction. Obviously, the best thing to do is not to band at all, if possible.
Iingn hasthe been past decade, pulmonary artery bandthe preferred surgical treatment for infants with cardiac failure due to large left-to-right shunts at the ventricular level. Infants with this type of palliation undergo closure of the defect and removal of the pulmonary band a few years later. The alternative to this two-stage technique is primary closure of the defect in infancy, and the choice between these two options is influenced primarily by the confidence and experience of each surgical team in performing intracardiac surgery in small infants. Four of our patients who had undergone the two-stage procedure later required another intracardiac operation to close a residual shunt. At this time impressive constriction of the pulmonary artery at the previous band-site was noted, and pulmonary artery reconstruction was required along with the shunt closure. These experiences prompted us to recall children who had had the two-stage procedure for late hemodynamic studies. These studies, together with pertinent operative findings in the 4 cases mentioned above, form the basis of this report. From the Departments of Cardiology and Cardiovascular Surgery, The Montreal Children's Hospital and McGill University. Read at the Fifty-second Annual Meeting of The American Association for Thoracic Surgery, Los Angeles, Calif., May I, 2, and 3, 1972.
32
Patients and results
Seventy-two infants and small children had pulmonary arteries banding between 1960 and 1972. Half of this group had isolated high-flow ventricular septal defects (VSD), and the remainder had more complex abnormalities. Sixty-six of these patients were under 1 year of age, and 56 of these were less than 6 months old. Thirty-four children later underwent pulmonary artery debanding and defect repair. Of the 29 long-term survivors, 18 have been restudied and will henceforth be referred to as the Restudy Group. This group includes children suspected of having a residual defect and those who lived close enough to this center to return conveniently for hemodynamic evaluation. Except for the fact that the Restudy Group contained those children suspected of having residual VSD, it was representative of the entire group of patients with pulmonary artery debanding. For example, the mean ages for banding and debanding in the larger group were 5 and 51 months, while in the Restudy Group these ages were 5 and 53 months. The late evaluation in the latter patients was done at an average age of 100 months with a range from 30 to 150 months. The present report is concerned with the state of the reconstructed pulmonary artery at the time of restudy, an average of 4 years after debanding. The data consist of pres-
Volume 65 Number 1 Jonuory, 1973
sure gradients and angiographic measurements of pulmonary artery size. Data on residual left-to-right shunts are presented since they influence the interpretation of the pressure data. At restudy, right heart catheterizations were performed, and cineangiograms in two planes were made. Pulmonary artery measurements were taken from the lateral angiogram after injection of contrast material into the right ventricle. Pulmonary artery diameter at the site of debanding was related to its diameter just above the annulus and expressed as a ratio. The results are shown in Tables I and II. Representative angiograms, which demonstrate the lowest and highest pulmonary artery-to-annulus ratios as well as the ratio close to the mean for the entire group, are shown in Figs. 1,2, and 3. The tables indicate a modest band-site gradient ranging from 6 to 48 mm. Hg in those patients with an intact ventricular septum and from 18 to 72 mm. Hg in those with a residual VSD. Similarly, the reduction in pulmonary artery diameter compared to that in normal subjects (Table II) is modest, with the diameter about 75 per cent of normal size. Four of these patients were reoperated upon to close the residual VSD and to enlarge the strictured pulmonary artery. The observations made during these reoperations provide additional data for this study and are shown in Table III. In 3 of the 4 there was significant restenosis at the bandsite, necessitating plastic repairs. The cicatrization was extremely pronounced in 1 case, and stenosis will likely recur in the future despite excision of the anterior half of the stricture and reconstruction with interrupted sutures. Although the excised segment was 1 em. wide, fibrosis remained in the margins. Discussion The hemodynamic studies which we undertook some time after debanding show a tendency to moderate recurrence of stenosis at the band-site. The figures are
Pulmonary artery after debanding
33
Table I. Right ventricular and pulmonary artery pressures 4 years after debanding
VSD closed (12 patients) Mean Range
40 28-60
20 12-40
19 6-48
Residual VSD (6 patients) Mean Range
76 60-96
31 22-42
45 18-72
Legend: RV, Right ventricle. PA, Pulmonary artery. VSD, Ventricular septal defect.
Table II. Pulmonary artery-annulus ratio Mean
Range
Normal subject Banded PA
1.07 0.40
1.02-1.18 0.31-0.48
Debanded Patch repair Dilatation only
0.82 0.70
0.71-0.97 0.56-0.90
Legend: PA, Pulmonary artery.
by no means alarming and may even be considered reassuring in view of the moderate gradients at rest. On the other hand, the children are still growing, and none of them has begun the adolescent growth spurt which will result in much larger pressure gradients if the strictures are fixed and do not grow. That this is a genuine matter for concern is suggested from our observations at reoperation on 4 of these children, in whom fibrosis at the band-site tended to be impressive. Technical modifications in both banding and debanding might reduce the stricture at the band-site. In our patients, either umbilical tape or Teflon-covered tape was used for banding. Although the latter came off more easily, we always found dense fibrosis beneath the tape where the pulmonary artery wall had been replaced by scar tissue. The specific fabric probably is not too important since most of the fibrosis is caused by the physical presence of the band, which creates pressure necrosis beneath it and extreme turbulence within the pulmonary
The Journal of
34
Dobell et al.
Fig. 1. Lateral angiogram on a 5-year-old girl 10 months after debanding and dilatation of pulmonary artery stricture. Right ventricular systolic pressure was 96 mm. Hg, distal pulmonary artery pre ssure was 38 mm. Hg, the ventr icular septal defect was open , and the pulmonary artery-annulus ratio was 0.56.
Fig. 2. Lateral angiogram on a 7-year-old girl 4 years after closure of the ventricular septal defect and dilatation of the pulmonary artery after band removal. Right ventricular systolic pressure was 50 rnm. Hg, distal pulmonary artery pressure was 40 mrn. Hg, and the pulmon ary artery-annulus ratio was 0.90.
artery. The progressive development of the arterial lesion of banding has been thoroughly presented by Berry.' Umbilical tape is not always completely removable, and thus a tape that resists invasion is preferable. The Teflon-covered band that we have used is unnecessaril y wide. In this regard, the experience at the Hospital for Sick Children, Great Ormond Street, is of interest. 6 Sur-
Thorac ic a nd Cardiovascular Surgery
Fig. 3. Lateral angiogram on a 9-year-old boy 6 years after debanding and pericardial patch repair of the pulmonary artery . Right ventr icular systolic pressure was 60 mm. Hg, distal pulmonary artery pressure was 25 mm. Hg, and proximal pulmonary artery pressure was 50 mm. Hg,
geons there claim satisfaction with narrow bands of silk ligatures, 1.2 mm. in diameter. A heavy synthetic ligature would be more easily removed. It seems important to us to reduce the length of scar to a minimum by using narrow bands. Another consideration in limiting the amount of stricture is reduction of the interval between banding and debanding. Regrettably, the arterial lesion of banding can be well developed by 14 weeks,1 but late complications such as migration into the pulmonary artery' and calcification1 suggest that debanding should be done electively at an early date. Another interesting lesion related to banding is acquired pulmonic stenosis as suggested by Hunt and his associates.' They noticed pulmonary valve thickening and commissural fusion when the band was placed within 15 mm. of the pulmonary valve annulus . We too have noticed this lesion and agree that it is probably secondary to the trauma of the valve cusps striking the narrowed pulmonary artery. We suspect that turbulence alone contributes to the valve fibrosis. Although pulmonary valve insufficiency has not been detected clinically, pressure tracings suggest its presence in a number of our patients. " Our current position on banding versus
Volume 65
Pulmonary artery after debanding
Number 1
35
Jonuory, 1973
Table III. Data on 4 patients who had second intracardiac operations Time since deCase banding (mo.) No. 1* 2 3 4
10 20 19 15
Systolic pressure RV
96 76 81 96
I PA 38 20 24
PA-
annulus ratio
0.56 0.60 0.78 0.63
Size of residual VSD (mm.)
I.D. of PA at band-site (mm.)
Repair of PAt
PA at operation
13 12 14
None Patch Patch Excision of anterior scar
Posterior ridge Fibrous ring Dense scar
10
3 10 5
Legend: RV, Right ventricle. PA, Pulmonary artery. VSD, Ventricular septal defect. 1.0., Inner diameter.
'This patient had double-outlet right ventricle. tThe repair was done at the second intracardiac operation.
closure of the defect in infancy is to follow the latter course- in most instances and reserve banding for the more complex lesions such as double-outlet right ventricle. Since 1960 we have closed the VSD primarily in 14 very ill infants with one death. Banding alone has had a higher mortality rate in our experience with VSD, and it is appreciably higher with more complex lesions. Our initial interest in banding was not based on any supposed intolerance of infants to cardiopulmonary bypass, because we have always found that babies withstand bypass as well as if not better than older children. However, we were concerned about the lack of fibrous tissue in the ventricular septum and feared a higher rate of residual VSD than in older children. It is obvious from the small series presented herein that the two-stage approach in our hands has not solved this problem.
only after serious consideration of the two other options, namely, supportive medical therapy with later defect closure and defect closure in infancy. Banding will still be the preferred treatment in certain infants. A narrow band hopefully will reduce the longitudinal extension of fibrosis in the pulmonary artery. REFERENCES
2
3
4
Summary and conclusions
The application of a band to the main pulmonary artery followed by its removal sometime later leads to a permanent fibrous stricture at the band-site. Our studies on 18 children an average of 4 years after band removal indicate mild-to-moderate obstruction in most patients as judged by pressure gradients and angiography. We reoperated upon 4 patients to close residual defects and were impressed with the marked fibrosis at the band-site in this group. Pulmonary artery banding should be done
5
6
Berry, C. L.: Changes in the Wall of the Pulmonary Artery After Banding, J. Pathol. 99: 29, 1969. Ching, E., DuShane, J. W., McGoon, D. C., and Danielson, G. K.: Total Correction of Ventricular Septal Defect in Infancy Using Extracorporeal Circulation, Ann. Thorac. Surg. 12: 1, 1971. Ebert, P. A., Cane nt, R. V., Jr., Spach, M. S., and Sabiston, D. C., Jr.: Late Cardiodynamics Following Correction of Ventricular Septal Defects With Previous Pulmonary Artery Banding, J. THORAC. CARDIOVASC. SURG. 60: 516, 1970. Hunt, C. E., Formanek, G., Levine, M. A., Castaneda, A., and Moller, J. H.: Banding of the Pulmonary Artery: Results in 111 Children, Circulation 43: 395, 1971. Rohmer, 1., Brom, A. G., and Nauta, J.: Bands Inside the Pulmonary Artery: A Complication of the Dammann-Muller Procedure, Ann. Thorac. Surg. 3: 449, 1967. Stark, J., Aberdeen, E., Waterston, D. 1., Bonham-Carter, R. E., and Tynan, M.: Pulmonary Artery Constriction (Banding): A Report of 146 Cases, Surgery 65: 808, 1969.
Discussion DR. A. ROBERT CORDELL Winston-Salem, N. C.
We are again indebted to Dr. Dobell and his group for this very detailed study of a group of
The Journal of
36
Dobell et al.
Thoracic and Cardiovascular Surgery
patients which many of us have found to be extremely interesting although difficult to treat. Our experience with debanding has been more limited and has included 8 patients thus far. However, we look with concern upon 35 other patients in our institution who await debanding and will undoubtedly require this operation. One of these 8 patients died because of intense scarring and thinning, such as that mentioned by Dr. Dobell. The band in this patient had migrated to the bifurcation of the pulmonary artery and had produced intense periarterial fibrosis, scarring, and thinning of both pulmonary artery trunks. Repair was therefore extremely difficult. [Slide] Adequate relief of the gradient at this portion in the pulmonary trunk was not attained, and examination at autopsy suggested that the insertion of a bifurcated homograft might have restored relatively normal caliber of each pulmonary trunk beyond the bifurcation of the common pulmonary artery. It is significant that thus far in our experience every pulmonary artery has shown marked thinning, severe stenosis, and marked scarring when approached for definitive correction. In all of these patients, either cotton or Dacron was used.
[Slide] A review of materials used in pulmonary banding suggests that Dacron covered by silicone rubber produces less scarring than other materials while at the same time giving adequate strength. The minimal tissue reaction is being investigated currently in the laboratory. We think the luminal caliber of 12 mm. is necessary in order to keep the gradient as low as possible in these patients. Therefore, we would like to emphasize that pulmonary banding should be limited to the few desperately ill infants which are not candidates for direct repair. DR. A. R. C. DOBELL (Closing) I appreciate Dr. Cordell's remarks, and I think we are in total agreement. Perhaps I can reiterate that I don't think the solution will be in choosing some other type of band material. Banding always produces a pulmonary artery lesion, and the surgeon must try to restrict the length of this stricture, with a view, possibly, to excising it at the time of correction. Obviously, the best thing to do is not to band at all, if possible.