Pulmonary Artery Sling Ashwinikumar Pawade, FRCS, Marc R. de Leval, FRCS, Martin J. Elliott, FRCS, and Jaroslav Stark, FRCS The Hospital for Sick Children, London, England
Eighteen patients who underwent surgical treatment of pulmonary artery sling at this institution since 1969 were reviewed. Four of them had associated tracheal stenoses produced by complete cartilaginous rings (stovepipe trachea). All patients underwent operation. The median age at operation was 180 days (range, 27 days to 54 months). In the 14 patients with isolated pulmonary sling, the operation consisted of division of left pulmonary artery and reimplantation into the main pulmonary artery anterior to the trachea. In the 4 patients with stovepipe trachea, the stenotic tracheal segment was
resected on cardiopulmonary bypass and the left pulmonary artery was brought anterior to the trachea before the latter was reanastomosed to the main pulmonary artery. There were no early deaths. One patient died late. The pulmonary artery anastomosis was patent in all 14 patients investigated postoperatively. Three patients have residual tracheobronchial problems. One patient is mentally retarded and is institutionalized. All other patients are symptom-free and growing normally and have normal chest radiographs. (Ann Tkorac Surg 1992;54:967-70)
P
nous rings, the so-called stovepipe trachea. The age at which symptoms were first noticed ranged from 1 day to 4 months (median, 1day). All the patients had wheeze, 11 patients had additional stridor, 7 patients had recurrent chest infections, and 3 patients fed poorly and failed to thrive. Eight patients were in acute respiratory failure and had to be ventilated at some stage before the operation; 6 of them were extubated successfully before operation. Predominant signs were stridor, tachypnea, and intercostal recession. The interval between the onset of symptoms and consultation for treatment ranged from 1 day to 19 months (median, 4 months). Two patients treated were identical twins. Associated abnormalities were as follows: 4 patients had stovepipe trachea, 1 patient had a fibrous tracheal stricture, and 1 patient had a microtrachea. The patient with microtrachea died postoperatively, but the nature of the tracheal pathology was never determined. Two patients had agenesis of the right lung, 1 with dextrocardia and hemivertebra. One patient had subglottic stenosis, and 1 had Robert’s syndrome, dextrocardia, left isomerism, and left superior vena cava. Diagnosis was established predominantly by a barium swallow in 17 patients, although it was aided by an additional angiogram in 6 patients, magnetic resonance imaging in 2 patients, and computed tomographic scan in 1 patient. In 1 patient the barium failed to fill the esophagus adequately and the diagnosis was established by magnetic resonance imaging alone. Chest roentgenogram was unremarkable in 6 patients; it showed a hyperinflated left lung in 3 patients, right upper lobe collapse in 5 patients, obstructive emphysema of the right upper lobe in 1 patient, a small right lung in 1 patient, and absent right lung in 2 patients. A high-kV chest radiograph using special filters and magnification was found to be particularly useful. A long, narrow segment was suggestive of a stovepipe trachea,
ulmonary artery sling is a vascular abnormality wherein the left pulmonary artery arises from the right pulmonary artery and then traverses between the esophagus and the trachea toward the hilum of the left lung. This produces a sling around the distal trachea and the proximal main bronchi. Respiratory embarrassment can be caused by either mechanical compression, tracheomalacia, or long-segment tracheal stenosis due to associated complete cartilaginous rings of the trachea (the so-called 0 ring, napkin ring, or stovepipe trachea). The combination is sometimes called ring-sling syndrome [11. Anomalous left pulmonary artery was first described in 1897 as a postmortem finding by Glaevecke and Doehle [2]. The term pulmonary artery sling was used by Contro and associates [3] in 1958 and has been popular ever since. In 1954 Potts and colleagues [4] described a repair consisting of division of the left pulmonary artery and reanastomosis of the two ends anterior to the trachea. The initial reports of surgical repair were dismal, with mortalities quoted from 38% to 50% [5, 61. However, recent reports using microvascular surgery and heparin have been more encouraging [7-91. We report our experience with 18 patients treated at our department since 1969.
Material and Methods Pa f ien fs Since 1969, 18 patients (11 male and 7 female) underwent surgical treatment of pulmonary artery sling. Six patients have been previously reported [7, 91. Four patients had associated tracheal strictures due to complete cartilagiAccepted for publication Aug 12, 1992. Address reprint requests to Mr Stark, The Hospital for Sick Children, Great Ormond St, London, WClN 3JH, England.
0 1992 by
The Society of Thoracic Surgeons
0003-4975/92/$5.00
968
PAWADE ET AL PULMONARY ARTERY SLING
Ann Thorac Surg 1992;54:967-70
whereas a discrete narrowing localized to the lower end of the trachea indicated simple mechanical compression by a pulmonary artery sling. Currently color-flow Doppler echocardiography can establish the diagnosis of pulmonary artery sling with great accuracy. A preoperative bronchoscopy was performed in 11 patients. A stovepipe trachea was suspected when complete tracheal rings could be visualized and when the posterior wall of the trachea failed to move with the Venturi jet. This was observed in 4 patients. Currently we perform bronchoscopy before operation under the same anesthesia. The diagnosis of associated tracheal problems will determine the approach and also the need for the use of cardiopulmonary bypass.
using interrupted sutures of 6-0 Prolene (Ethicon, Somerville, NJ). The tracheal tube was maintained high in the trachea. The anastomosis was tested to 40 cm H,O for any evidence of an air leak and was then sealed with fibrin glue (Tisseel; Immuno, Austria). After rewarming, the patient was weaned from cardiopulmonary bypass.
Surgical Technique
Results Mortality
The age at operation ranged from 27 days to 54 months (mean, 180 35 days). In patients with isolated pulmonary artery sling our preferred approach is through a left thoracotomy (10 patients). If cardiopulmonary bypass is needed, we use midline sternotomy. We elected to use cardiopulmonary bypass in 8 patients for the following reasons: tracheal resection (4 patients), agenesis of the right lung (2), origin of the left pulmonary artery too far to the right (l),and severe bradycardia caused by clamping of the left pulmonary artery (1). In patients with isolated pulmonary artery sling, the surgical technique employed was as described by Dunn and associates (71. A left thoracotomy was performed through the fourth intercostal space. The ligamentum arteriosum or persistent ductus arteriosus was divided, and the anomalous left pulmonary artery was identified as it emerged from underneath the aortic arch. The pulmonary artery was dissected as deep into the mediastinum as possible. After systemic heparinization (1 mgkg body weight) the left pulmonary artery was occluded with snares at the primary branches. A vascular clamp was applied to the left pulmonary artery as deep as possible, and the artery was transected. The proximal stump was carefully oversewn with fine monofilament suture. Care was taken not to obstruct the trachea with the vascular clamp. The pericardium was opened posterior to the left phrenic nerve, and the main pulmonary artery was dissected. A partial occlusion clamp was used to isolate a portion of the main pulmonary artery, which was then incised. The left pulmonary artery was trimmed obliquely, brought through the pericardial incision, and sutured to the main pulmonary artery end-to-side, using a fine monofilament suture. A large anastomosis was constructed. In patients with stovepipe trachea, the operation was performed through a median sternotomy. The trachea was mobilized well above and below the stricture. The ligamentum arteriosum was divided. Cardiopulmonary bypass was then established under mild hypothermia. The tracheal stricture was now excised, making sure that no complete rings were left behind. The left pulmonary artery was brought anteriorly through the gap in the trachea. Primary tracheal anastomosis was performed
*
Postoperative Care Postoperatively, the patients were ventilated in the intensive therapy unit, ranging from 2 to 58 days (median, 4 days). The stay in the intensive therapy unit ranged from 2 days to 70 days (median, 6 days). The hospital stay ranged from 5 days to 90 days (median, 11 days).
There were no early deaths. One patient died late (5.5%). This patient had a pulmonary artery sling that was repaired through a left thoracotomy. A preoperative bronchoscopy showed that the trachea was considerably narrow. A diagnosis of microtrachea was made. The exact nature of the tracheal rings was not noted. The patient had respiratory difficulty on attempted extubation and subsequently underwent tracheal dilation and tracheostomy. She was readmitted 7 days after discharge in respiratory failure. She was ventilated, but air trapping and bilateral pneumothoraces developed and she died. A postmortem examination was not performed; therefore the exact pathological nature of the microtrachea remains unclear.
Morbidity Two patients had to be reintubated after their first extubation because of atelectases. They were subsequently extubated successfully. Six patients had postoperative respiratory infections, which were treated with antibiotics and physiotherapy. One patient had a paralyzed left hemidiaphragm, which needed plication. The follow-up is 100% complete and ranges from 2 months to 21 years (mean, 108 & 35 months). Three patients have residual tracheobronchial problems manifest as wheeze and repeated respiratory infections. Two of them had undergone tracheal resections for stovepipe trachea. One of these has a lower tracheal stricture at the site of tracheal anastomosis, which stops short of the origins of the main bronchi. The other patient (mentally subnormal and institutionalized) has tracheomalacia at the carina. Both of them have to undergo regular bronchoscopy and dilation. The third patient with a residual problem had agenesis of the right lung associated with a pulmonary sling. He has malacia of the left upper lobe bronchus and requires frequent admissions to the intensive therapy unit for ventilation after atelectasis of the left upper lobe. All other patients have been reported to have normal growth and development. Postoperative ventilation/perfusion scan was performed in 13 patients and showed a satisfactory perfusion on the repaired side. Patency of the left pulmonary artery was established in 1 additional patient by a computed
PAWADE ET AL PULMONARY ARTERY SLING
Ann Thorac Surg
1992;54:967-70
tomographic scan, which was basically undertaken to assess the tracheal stricture. The 3 patients most recently operated on are awaiting their ventilation/perfusion scans.
Comment Pulmonary artery sling is a condition that generally manifests in infancy and often with severe symptoms. Death from airway obstruction has been reported as early as 2 days after birth [3] and is common before the age of 6 months in untreated patients [lo]. Very few cases of the asymptomatic form of pulmonary artery sling have been reported [ll-131. However, determination of the prevalence of the asymptomatic form of this disease is largely conjectural. In view of the seriousness of this condition and the fact that reports of surgical management have been encouraging, our policy has been to offer operation as soon as the diagnosis has been made. Although all cases are grouped under a common category of pulmonary artery sling, we believe that there are two distinctly different entities. Group 1 includes patients with pulmonary artery sling. In this group patients can be operated on through a left thoracotomy and without cardiopulmonary bypass. The operation is relatively simple, and a complete cure can be achieved with a very low early mortality. Except for 1 patient who has bronchomalacia of the left upper lobe and agenesis of the right lung, no patient in this group has any residual problems. This indicates that in most of the patients the tracheal manifestations are due to a simple mechanical compression by the “sling” and therefore reversible once the compression is relieved. Group 2 patients, on the other hand, have a coexisting tracheal stenosis due to complete tracheal rings and an absence of any substantial pars membranacea. This entity is also called a “stovepipe,” ”0 ring,” or ”napkin ring” trachea. This was first described by Scheid in 1938 [14]. This association of pulmonary artery sling and stovepipe trachea was termed by Berdon and associates [l] as the ring-sling complex. Four of our patients (22%)were diagnosed to have this syndrome preoperatively. The patient with microtrachea who died probably had the same problem, although this was never diagnosed with certainty. Associated stovepipe trachea may be suspected on plain chest radiograph, which may show normal findings or a symmetrical overaeration but no evidence of selective right-sided air trapping, emphysema, or atelectasis as in patients with isolated pulmonary artery sling [l]. This is to be expected as the problem is central in the trachea itself. High-kV filtered radiography using magnification [15] can often demonstrate the tracheal anomaly. A longsegment stricture is highly suggestive of a stovepipe trachea, whereas a small discrete stricture localized at the lower end of the trachea is probably from simple mechanical compression. The final diagnosis rests on a bronchoscopy, which is best carried out just before definitive operation. Visualization of complete tracheal rings and absence of the normal movement of the posterior membranous wall of
969
the trachea with the Venturi jet is diagnostic of stovepipe trachea. As suggested by Grillo in the discussion of Dunn and associates [7] and by Jonas and associates [8], the primary approach in these cases is that of resection of the stricture and reanastomosis of the trachea behind the left pulmonary artery. The operation is carried out through a median sternotomy on cardiopulmonary bypass. Although the mortality for tracheal resection in the present series was nil, the morbidity has been considerable, with 2 patients continuing to have respiratory symptoms from residual tracheobronchial problems. It is therefore vital that a diagnosis of the ring-sling syndrome is made as soon as possible. The mainstay of the diagnosis of pulmonary artery sling has been the barium esophagogram. A lateral view discloses an anterior indentation of the esophagus, a finding described with no other vascular lesion [16, 171. We recommend that careful cardiological evaluation including echocardiography should be performed in all the patients to rule out associated cardiovascular lesions, which have been reported in 58% to 83% of patients [13]. Color-flow Doppler echocardiography may demonstrate the “sling” and establish the diagnosis. If there are any further doubts, angiocardiography or magnetic resonance imaging may be used. The decision regarding the use of a median sternotomy and cardiopulmonary bypass depends on the presence or absence of tracheal stenosis. We prefer to use cardiopulmonary bypass during tracheal resections in infants, although such a practice is not universal [18, 191. If there are associated cardiac lesions they can be repaired simultaneously in the same sitting [20]. Pulmonary artery sling could be treated surgically with a low mortality and morbidity. Patients with associated stovepipe trachea have poorer results when compared with those with pulmonary artery sling alone; early operation offers the only hope in this combination of lesions.
References 1. Berdon WE, Baker DM, Wung JT, et al. Complete cartilagering tracheal stenosis associated with anomalous left pulmonary artery: the ring-sling complex. Radiology 1984;152: 57-64. 2. Glaevecke H, Doehle H. Uber cine seltene angeborene Anomalie der Pulmonalarterie. Munch Med Wochenschr 1897;44:950-1. 3. Contro S, Miller RA, White M, Potts WJ. Bronchial obstruction due to pulmonary artery abnormalities. I. Vascular ring. Circulation 1958;17418-23. 4. Potts WJ, Holinger PM, Rosenblum AH. Anomalous left pulmonary artery causing obstruction to right main bronchus. JAMA 1954;155:1409-11. 5. Rheuban KS, Ayres N, Still G, Alford B. Pulmonary artery sling: a new diagnostic tool and clinical review. Paediatrics 1982;69:472-5. 6. Sade RM, Rosenthal A, Fellows K, CastanaedaA. Pulmonary artery sling. J Thorac Cardiovasc Surg 1975;69:33346. 7. Dunn JM, Gordon I, Chrispin AR, et al. Early and late results of surgical correction of pilmonary artery shng. Ann Thorac Surg 1979;28:230-8. 8. Jonas RA, Spevak PJ, McGill T, Castanaeda AR. Pulmonary
970
PAWADE ET AL PULMONARY ARTERY SLING
artery sling: primary repair by tracheal resection in infancy. J Thorac Cardiovasc Surg 1989;97:548-50. 9. Westaby S, Dinwiddie R, Chrispin A, Stark J. Pulmonary artery sling in identical twins-report of two cases. Thorac Cardiovasc Surg 1984;32:182-3. 10. Gumbiner CH, Mullins CE, McNamara DG. Pulmonary artery sling. Am J Cardiol 1980;45:311-5. 11. Dupuis C, Vaksmann G, Pernot C, et al. Asymptomatic form of left pulmonary artery sling. Am J Cardiol 1988;61:177-81. 12. Steinberg I. Anomalous (non-constricting) left pulmonary artery. Circulation 1964;29:897-900. 13. Philip T, Sumerling MD, Fleming J, Grainger MG. Aberrant left pulmonary artery. Clin Radiol 1972;23:153-9. 14. Scheid P. Missbilding des Traachealskelettes und der linken Arteria pulmonalis mit Erstickungstod bei 7 monate alt Kind. Frank Zeitschr Pathol 1938;52:114-6. 15. Joseph PM, Walter EB, Baker DH, et al. Upper airway
Ann Thorac Surg 1992;54:967-70
obstruction in infants and small children. Paediatric Radiology 1976;121:143-8. 16. Singleton EB, Wagner ML. Radiologic atlas of pulmonary abnormalities in children. Philadelphia: Saunders, 1971:85. 17. Capitano MA, Ramos R, Kirkpatrick JA. Pulmonary sling, roentgen observations. Am J Radiol 1971;112:28-34. 18. Nakayama DK, Harrison MR, de Lorimier AA, et al. Reconstructive surgery for obstructing lesions of the intrathoracic trachea in infants and small children. J Paediatr Surg 1982; M200-3.
19. Mattingley WT Jr, Belin RP, Todd El'. Surgical repair of congenital tracheal stenosis in an infant. J Thorac Cardiovasc Surg 1981;81:73&40. 20. Yamaguchi M, Oshima Y, Hosokawa Y, et al. Concomitant repair of congenital tracheal stenosis and complex cardiac anomaly in small children. J Thorac Cardiovasc Surg 1990; 100:181-7.
Eighteen patients who underwent surgical treatment of pulmonary artery sling at this institution since 1969 were reviewed. Four of them had associated tracheal stenoses produced by complete cartilaginous rings (stovepipe trachea). All patients underwent operation. The median age at operation was 180 days (range, 27 days to 54 months). In the 14 patients with isolated pulmonary sling, the operation consisted of division of left pulmonary artery and reimplantation into the main pulmonary artery anterior to the trachea. In the 4 patients with stovepipe trachea, the stenotic tracheal segment was
resected on cardiopulmonary bypass and the left pulmonary artery was brought anterior to the trachea before the latter was reanastomosed to the main pulmonary artery. There were no early deaths. One patient died late. The pulmonary artery anastomosis was patent in all 14 patients investigated postoperatively. Three patients have residual tracheobronchial problems. One patient is mentally retarded and is institutionalized. All other patients are symptom-free and growing normally and have normal chest radiographs. (Ann Tkorac Surg 1992;54:967-70)
P
nous rings, the so-called stovepipe trachea. The age at which symptoms were first noticed ranged from 1 day to 4 months (median, 1day). All the patients had wheeze, 11 patients had additional stridor, 7 patients had recurrent chest infections, and 3 patients fed poorly and failed to thrive. Eight patients were in acute respiratory failure and had to be ventilated at some stage before the operation; 6 of them were extubated successfully before operation. Predominant signs were stridor, tachypnea, and intercostal recession. The interval between the onset of symptoms and consultation for treatment ranged from 1 day to 19 months (median, 4 months). Two patients treated were identical twins. Associated abnormalities were as follows: 4 patients had stovepipe trachea, 1 patient had a fibrous tracheal stricture, and 1 patient had a microtrachea. The patient with microtrachea died postoperatively, but the nature of the tracheal pathology was never determined. Two patients had agenesis of the right lung, 1 with dextrocardia and hemivertebra. One patient had subglottic stenosis, and 1 had Robert’s syndrome, dextrocardia, left isomerism, and left superior vena cava. Diagnosis was established predominantly by a barium swallow in 17 patients, although it was aided by an additional angiogram in 6 patients, magnetic resonance imaging in 2 patients, and computed tomographic scan in 1 patient. In 1 patient the barium failed to fill the esophagus adequately and the diagnosis was established by magnetic resonance imaging alone. Chest roentgenogram was unremarkable in 6 patients; it showed a hyperinflated left lung in 3 patients, right upper lobe collapse in 5 patients, obstructive emphysema of the right upper lobe in 1 patient, a small right lung in 1 patient, and absent right lung in 2 patients. A high-kV chest radiograph using special filters and magnification was found to be particularly useful. A long, narrow segment was suggestive of a stovepipe trachea,
ulmonary artery sling is a vascular abnormality wherein the left pulmonary artery arises from the right pulmonary artery and then traverses between the esophagus and the trachea toward the hilum of the left lung. This produces a sling around the distal trachea and the proximal main bronchi. Respiratory embarrassment can be caused by either mechanical compression, tracheomalacia, or long-segment tracheal stenosis due to associated complete cartilaginous rings of the trachea (the so-called 0 ring, napkin ring, or stovepipe trachea). The combination is sometimes called ring-sling syndrome [11. Anomalous left pulmonary artery was first described in 1897 as a postmortem finding by Glaevecke and Doehle [2]. The term pulmonary artery sling was used by Contro and associates [3] in 1958 and has been popular ever since. In 1954 Potts and colleagues [4] described a repair consisting of division of the left pulmonary artery and reanastomosis of the two ends anterior to the trachea. The initial reports of surgical repair were dismal, with mortalities quoted from 38% to 50% [5, 61. However, recent reports using microvascular surgery and heparin have been more encouraging [7-91. We report our experience with 18 patients treated at our department since 1969.
Material and Methods Pa f ien fs Since 1969, 18 patients (11 male and 7 female) underwent surgical treatment of pulmonary artery sling. Six patients have been previously reported [7, 91. Four patients had associated tracheal strictures due to complete cartilagiAccepted for publication Aug 12, 1992. Address reprint requests to Mr Stark, The Hospital for Sick Children, Great Ormond St, London, WClN 3JH, England.
0 1992 by
The Society of Thoracic Surgeons
0003-4975/92/$5.00
968
PAWADE ET AL PULMONARY ARTERY SLING
Ann Thorac Surg 1992;54:967-70
whereas a discrete narrowing localized to the lower end of the trachea indicated simple mechanical compression by a pulmonary artery sling. Currently color-flow Doppler echocardiography can establish the diagnosis of pulmonary artery sling with great accuracy. A preoperative bronchoscopy was performed in 11 patients. A stovepipe trachea was suspected when complete tracheal rings could be visualized and when the posterior wall of the trachea failed to move with the Venturi jet. This was observed in 4 patients. Currently we perform bronchoscopy before operation under the same anesthesia. The diagnosis of associated tracheal problems will determine the approach and also the need for the use of cardiopulmonary bypass.
using interrupted sutures of 6-0 Prolene (Ethicon, Somerville, NJ). The tracheal tube was maintained high in the trachea. The anastomosis was tested to 40 cm H,O for any evidence of an air leak and was then sealed with fibrin glue (Tisseel; Immuno, Austria). After rewarming, the patient was weaned from cardiopulmonary bypass.
Surgical Technique
Results Mortality
The age at operation ranged from 27 days to 54 months (mean, 180 35 days). In patients with isolated pulmonary artery sling our preferred approach is through a left thoracotomy (10 patients). If cardiopulmonary bypass is needed, we use midline sternotomy. We elected to use cardiopulmonary bypass in 8 patients for the following reasons: tracheal resection (4 patients), agenesis of the right lung (2), origin of the left pulmonary artery too far to the right (l),and severe bradycardia caused by clamping of the left pulmonary artery (1). In patients with isolated pulmonary artery sling, the surgical technique employed was as described by Dunn and associates (71. A left thoracotomy was performed through the fourth intercostal space. The ligamentum arteriosum or persistent ductus arteriosus was divided, and the anomalous left pulmonary artery was identified as it emerged from underneath the aortic arch. The pulmonary artery was dissected as deep into the mediastinum as possible. After systemic heparinization (1 mgkg body weight) the left pulmonary artery was occluded with snares at the primary branches. A vascular clamp was applied to the left pulmonary artery as deep as possible, and the artery was transected. The proximal stump was carefully oversewn with fine monofilament suture. Care was taken not to obstruct the trachea with the vascular clamp. The pericardium was opened posterior to the left phrenic nerve, and the main pulmonary artery was dissected. A partial occlusion clamp was used to isolate a portion of the main pulmonary artery, which was then incised. The left pulmonary artery was trimmed obliquely, brought through the pericardial incision, and sutured to the main pulmonary artery end-to-side, using a fine monofilament suture. A large anastomosis was constructed. In patients with stovepipe trachea, the operation was performed through a median sternotomy. The trachea was mobilized well above and below the stricture. The ligamentum arteriosum was divided. Cardiopulmonary bypass was then established under mild hypothermia. The tracheal stricture was now excised, making sure that no complete rings were left behind. The left pulmonary artery was brought anteriorly through the gap in the trachea. Primary tracheal anastomosis was performed
*
Postoperative Care Postoperatively, the patients were ventilated in the intensive therapy unit, ranging from 2 to 58 days (median, 4 days). The stay in the intensive therapy unit ranged from 2 days to 70 days (median, 6 days). The hospital stay ranged from 5 days to 90 days (median, 11 days).
There were no early deaths. One patient died late (5.5%). This patient had a pulmonary artery sling that was repaired through a left thoracotomy. A preoperative bronchoscopy showed that the trachea was considerably narrow. A diagnosis of microtrachea was made. The exact nature of the tracheal rings was not noted. The patient had respiratory difficulty on attempted extubation and subsequently underwent tracheal dilation and tracheostomy. She was readmitted 7 days after discharge in respiratory failure. She was ventilated, but air trapping and bilateral pneumothoraces developed and she died. A postmortem examination was not performed; therefore the exact pathological nature of the microtrachea remains unclear.
Morbidity Two patients had to be reintubated after their first extubation because of atelectases. They were subsequently extubated successfully. Six patients had postoperative respiratory infections, which were treated with antibiotics and physiotherapy. One patient had a paralyzed left hemidiaphragm, which needed plication. The follow-up is 100% complete and ranges from 2 months to 21 years (mean, 108 & 35 months). Three patients have residual tracheobronchial problems manifest as wheeze and repeated respiratory infections. Two of them had undergone tracheal resections for stovepipe trachea. One of these has a lower tracheal stricture at the site of tracheal anastomosis, which stops short of the origins of the main bronchi. The other patient (mentally subnormal and institutionalized) has tracheomalacia at the carina. Both of them have to undergo regular bronchoscopy and dilation. The third patient with a residual problem had agenesis of the right lung associated with a pulmonary sling. He has malacia of the left upper lobe bronchus and requires frequent admissions to the intensive therapy unit for ventilation after atelectasis of the left upper lobe. All other patients have been reported to have normal growth and development. Postoperative ventilation/perfusion scan was performed in 13 patients and showed a satisfactory perfusion on the repaired side. Patency of the left pulmonary artery was established in 1 additional patient by a computed
PAWADE ET AL PULMONARY ARTERY SLING
Ann Thorac Surg
1992;54:967-70
tomographic scan, which was basically undertaken to assess the tracheal stricture. The 3 patients most recently operated on are awaiting their ventilation/perfusion scans.
Comment Pulmonary artery sling is a condition that generally manifests in infancy and often with severe symptoms. Death from airway obstruction has been reported as early as 2 days after birth [3] and is common before the age of 6 months in untreated patients [lo]. Very few cases of the asymptomatic form of pulmonary artery sling have been reported [ll-131. However, determination of the prevalence of the asymptomatic form of this disease is largely conjectural. In view of the seriousness of this condition and the fact that reports of surgical management have been encouraging, our policy has been to offer operation as soon as the diagnosis has been made. Although all cases are grouped under a common category of pulmonary artery sling, we believe that there are two distinctly different entities. Group 1 includes patients with pulmonary artery sling. In this group patients can be operated on through a left thoracotomy and without cardiopulmonary bypass. The operation is relatively simple, and a complete cure can be achieved with a very low early mortality. Except for 1 patient who has bronchomalacia of the left upper lobe and agenesis of the right lung, no patient in this group has any residual problems. This indicates that in most of the patients the tracheal manifestations are due to a simple mechanical compression by the “sling” and therefore reversible once the compression is relieved. Group 2 patients, on the other hand, have a coexisting tracheal stenosis due to complete tracheal rings and an absence of any substantial pars membranacea. This entity is also called a “stovepipe,” ”0 ring,” or ”napkin ring” trachea. This was first described by Scheid in 1938 [14]. This association of pulmonary artery sling and stovepipe trachea was termed by Berdon and associates [l] as the ring-sling complex. Four of our patients (22%)were diagnosed to have this syndrome preoperatively. The patient with microtrachea who died probably had the same problem, although this was never diagnosed with certainty. Associated stovepipe trachea may be suspected on plain chest radiograph, which may show normal findings or a symmetrical overaeration but no evidence of selective right-sided air trapping, emphysema, or atelectasis as in patients with isolated pulmonary artery sling [l]. This is to be expected as the problem is central in the trachea itself. High-kV filtered radiography using magnification [15] can often demonstrate the tracheal anomaly. A longsegment stricture is highly suggestive of a stovepipe trachea, whereas a small discrete stricture localized at the lower end of the trachea is probably from simple mechanical compression. The final diagnosis rests on a bronchoscopy, which is best carried out just before definitive operation. Visualization of complete tracheal rings and absence of the normal movement of the posterior membranous wall of
969
the trachea with the Venturi jet is diagnostic of stovepipe trachea. As suggested by Grillo in the discussion of Dunn and associates [7] and by Jonas and associates [8], the primary approach in these cases is that of resection of the stricture and reanastomosis of the trachea behind the left pulmonary artery. The operation is carried out through a median sternotomy on cardiopulmonary bypass. Although the mortality for tracheal resection in the present series was nil, the morbidity has been considerable, with 2 patients continuing to have respiratory symptoms from residual tracheobronchial problems. It is therefore vital that a diagnosis of the ring-sling syndrome is made as soon as possible. The mainstay of the diagnosis of pulmonary artery sling has been the barium esophagogram. A lateral view discloses an anterior indentation of the esophagus, a finding described with no other vascular lesion [16, 171. We recommend that careful cardiological evaluation including echocardiography should be performed in all the patients to rule out associated cardiovascular lesions, which have been reported in 58% to 83% of patients [13]. Color-flow Doppler echocardiography may demonstrate the “sling” and establish the diagnosis. If there are any further doubts, angiocardiography or magnetic resonance imaging may be used. The decision regarding the use of a median sternotomy and cardiopulmonary bypass depends on the presence or absence of tracheal stenosis. We prefer to use cardiopulmonary bypass during tracheal resections in infants, although such a practice is not universal [18, 191. If there are associated cardiac lesions they can be repaired simultaneously in the same sitting [20]. Pulmonary artery sling could be treated surgically with a low mortality and morbidity. Patients with associated stovepipe trachea have poorer results when compared with those with pulmonary artery sling alone; early operation offers the only hope in this combination of lesions.
References 1. Berdon WE, Baker DM, Wung JT, et al. Complete cartilagering tracheal stenosis associated with anomalous left pulmonary artery: the ring-sling complex. Radiology 1984;152: 57-64. 2. Glaevecke H, Doehle H. Uber cine seltene angeborene Anomalie der Pulmonalarterie. Munch Med Wochenschr 1897;44:950-1. 3. Contro S, Miller RA, White M, Potts WJ. Bronchial obstruction due to pulmonary artery abnormalities. I. Vascular ring. Circulation 1958;17418-23. 4. Potts WJ, Holinger PM, Rosenblum AH. Anomalous left pulmonary artery causing obstruction to right main bronchus. JAMA 1954;155:1409-11. 5. Rheuban KS, Ayres N, Still G, Alford B. Pulmonary artery sling: a new diagnostic tool and clinical review. Paediatrics 1982;69:472-5. 6. Sade RM, Rosenthal A, Fellows K, CastanaedaA. Pulmonary artery sling. J Thorac Cardiovasc Surg 1975;69:33346. 7. Dunn JM, Gordon I, Chrispin AR, et al. Early and late results of surgical correction of pilmonary artery shng. Ann Thorac Surg 1979;28:230-8. 8. Jonas RA, Spevak PJ, McGill T, Castanaeda AR. Pulmonary
970
PAWADE ET AL PULMONARY ARTERY SLING
artery sling: primary repair by tracheal resection in infancy. J Thorac Cardiovasc Surg 1989;97:548-50. 9. Westaby S, Dinwiddie R, Chrispin A, Stark J. Pulmonary artery sling in identical twins-report of two cases. Thorac Cardiovasc Surg 1984;32:182-3. 10. Gumbiner CH, Mullins CE, McNamara DG. Pulmonary artery sling. Am J Cardiol 1980;45:311-5. 11. Dupuis C, Vaksmann G, Pernot C, et al. Asymptomatic form of left pulmonary artery sling. Am J Cardiol 1988;61:177-81. 12. Steinberg I. Anomalous (non-constricting) left pulmonary artery. Circulation 1964;29:897-900. 13. Philip T, Sumerling MD, Fleming J, Grainger MG. Aberrant left pulmonary artery. Clin Radiol 1972;23:153-9. 14. Scheid P. Missbilding des Traachealskelettes und der linken Arteria pulmonalis mit Erstickungstod bei 7 monate alt Kind. Frank Zeitschr Pathol 1938;52:114-6. 15. Joseph PM, Walter EB, Baker DH, et al. Upper airway
Ann Thorac Surg 1992;54:967-70
obstruction in infants and small children. Paediatric Radiology 1976;121:143-8. 16. Singleton EB, Wagner ML. Radiologic atlas of pulmonary abnormalities in children. Philadelphia: Saunders, 1971:85. 17. Capitano MA, Ramos R, Kirkpatrick JA. Pulmonary sling, roentgen observations. Am J Radiol 1971;112:28-34. 18. Nakayama DK, Harrison MR, de Lorimier AA, et al. Reconstructive surgery for obstructing lesions of the intrathoracic trachea in infants and small children. J Paediatr Surg 1982; M200-3.
19. Mattingley WT Jr, Belin RP, Todd El'. Surgical repair of congenital tracheal stenosis in an infant. J Thorac Cardiovasc Surg 1981;81:73&40. 20. Yamaguchi M, Oshima Y, Hosokawa Y, et al. Concomitant repair of congenital tracheal stenosis and complex cardiac anomaly in small children. J Thorac Cardiovasc Surg 1990; 100:181-7.
