doi:10.1510/mmcts.2008.003343
Pulmonary artery sling with tracheal stenosis Viktor Hrasˇka*, Joachim Photiadis, Christoph Haun, Ehrenfried Schindler, Martin Schneider, Peter Murin, Boulos Asfour Department of Pediatric Cardiac Surgery, German Pediatric Heart Centre, Asklepios Clinic Sankt Augustin, Arnold Janssen Str. 29, 53757 Sankt Augustin, Germany Pulmonary artery sling (PAS) is a rare congenital heart disease in which the left pulmonary artery (LPA) originates from the right pulmonary artery (RPA) and encircles the distal trachea and right mainstem bronchus as it courses between the trachea and esophagus. Typically, patients with PAS have some respiratory symptoms, either due to external tracheal compression that can be corrected by relief of the sling mechanism, or due to severe diffuse tracheal stenosis with complete rings (ring-sling complex). The diagnosis of PAS is optimally made by echocardiography, while bronchoscopy is the key to the assessment of tracheal stenosis. Diagnosis is indication for surgery. Repair using a strategy of median sternotomy, cardiopulmonary bypass, division of the LPA and reimplantation into the main pulmonary artery (MPA), and simultaneous tracheal repair takes preference. Tracheal repair should be considered only in clinically symptomatic patients. The techniques of free tracheal autograft plasty or slide tracheoplasty offer promising results, and the choice of tracheal reconstruction should be guided by the clinical experience of the surgeon. Coexisting intracardiac pathologies are repaired at the same time. Postoperative care requires close multidisciplinary effort to achieve the best long-term result.
Keywords: Congenital heart disease; Pulmonary artery sling; Ring-sling complex; Tracheal stenosis; Vascular ring
Introduction Pulmonary artery sling (PAS) is a rare congenital condition in which the left pulmonary artery (LPA) originates from the right pulmonary artery (RPA) and encircles the distal trachea and right mainstem bronchus as it courses between the trachea and esophagus to reach the hilum of the left lung w1x. The ligamentum arteriosum or the ductus arteriosus originates from the main pulmonary artery (MPA), and passes anteriorly and superior to the left mainstem bronchus to join the descending thoracic aorta to * Corresponding author. Tel.: q49 2241-249 603; fax: q49 2241249 602 E-mail: [email protected] 䉷 2009 European Association for Cardio-thoracic Surgery
complete the vascular ring w2, 3x. The clinical outcome of patients with PAS depends on the associated tracheal lesions and complex cardiac anomalies. Coexisting diffuse tracheal stenosis, creating a ring-sling complex, is identified in up to 65% of patients with PAS w4x. Typically, stenosis of the trachea is due to complete tracheal rings and ranges from a profound degree of hypoplasia of the entire tracheobronchial tree to a discrete stenosis. Interestingly, despite compression of the tracheobronchial tree by the sling, tracheomalacia is usually not a feature. Congenital heart defects are found in 50% of PAS cases, the most common being atrial and ventricular septal defects, patent ductus arteriosus, left superior vena cava, and tetralogy of Fallot w5x. 1
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343 Current treatment protocol Treatment of patients with PAS requires close collaboration of pediatric cardiac surgeons and their medical counterparts. Diagnosis of PAS is optimally made using echocardiography, as it is rapid and non-invasive. All infants should undergo bronchoscopy to rule out tracheal stenosis secondary to congenital complete tracheal rings. Diagnosis is indication for surgery. Repair using a strategy of median sternotomy, cardiopulmonary bypass (CPB), LPA division and reimplantation into the MPA, and simultaneous tracheal repair takes preference. Tracheal repair should be considered only in clinically symptomatic patients. Coexisting intracardiac pathology is repaired or palliated at the same time w3, 5x. The postoperative care of these patients requires close vigilance by pediatric intensivists, anesthesiologists, and pediatric cardiac surgeons. The management of the reconstructed trachea requires close collaboration among these specialities in order to achieve the best long-term result w6, 7x
Surgical technique
Exposure of the stenotic trachea is performed by dissecting the space between the aorta and superior vena cava (SVC) (Videos 3 and 4). CPB is commenced (Video 5). Being on CPB provides complete freedom to manipulate the pulmonary arteries and respiratory support for the tracheal repair. During this time frame the endotracheal tube might be removed, and then either rigid or fiberoptic bronchoscopy is performed to confirm the extent and degree of stenosis. Needles can be placed through the trachea, using bronchoscopic visualization, to delineate the extent of stenosis externally.
Video 2. Extensive dissection and mobilization of the right pulmonary artery and the origin of the left pulmonary artery are carried out.
Repair of PAS with resection of the trachea and closure of the VSD in an infant In this specific symptomatic infant, the diagnosis was established by ECHO and confirmed by angiography and tracheography (Video 1). Intraoperative bronchoscopy demonstrated short-segment tracheal stenosis with complete tracheal rings involving the distal part of the trachea. Median sternotomy is performed. The thymus is completely resected, and the pericardium is harvested, and pretreated in glutaraldehyde for further use. The aorta and the pulmonary artery are dissected free, and the ductus arteriosus (or ligamentum) is ligated and divided. The LPA is identified as originating from the superior aspect of the RPA (Video 2).
Video 1. Diagnosis was made by ECHO and angiography.
2
Video 3. During dissection of the trachea, care is taken to avoid damaging the lateral tracheal blood supply, especially along the distal half of the trachea and at the level of the carina. The left pulmonary artery is carefully dissected away from the posterior trachea and anterior esophagus. Care is taken to avoid injury to the recurrent laryngeal nerve. Finally, the left pulmonary artery is dissected circumferentially up to the left hilar branches. This usually requires entering the left pleural space.
Video 4. The left pulmonary artery encircles and compresses the distal area of the trachea and right mainstem bronchus.
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343
Video 5. The standard techniques of cardiopulmonary bypass, including bicaval cannulation and moderate hypothermia (32 8C), are used. A left ventricular vent is inserted through the entrance of the right pulmonary veins.
Video 6. The trachea is transected at the narrowest point. The left pulmonary artery is brought anterior above the carina. The very distal complete ring above the carina is resected first. Note the close relationship of the bronchus suis and the carina.
Video 8. Using a continuous 6-0 polyglyconate suture, end-to-end anastomosis is fashioned. Care is taken to avoid the placement of suture material in the tracheal mucosa, in order to minimize granulation tissue formation.
Video 9. A pedicled pericardial patch is harvested to separate the tracheal anastomosis from the mediastinum. Care is taken to stay away from the phrenic nerve. The mediastinum is filled with saline, and the patient is ventilated to a peak airway pressure of 35–40 cm H2O to assess the anastomosis for leaks.
The possibility of kinking of the LPA and compression of the trachea by the LPA are evaluated. Usually the takeoff of the LPA is at an angle of nearly 1808, and that may cause proximal kinking. The decision is made in favor of translocation of the LPA (Video 10).
Video 7. Gradually, the remaining stenotic rings (3 rings) are resected to achieve an optimal lumen of the trachea. Note the high mobility of the proximal segment of the trachea as a prerequisite of tension free anastomosis.
The aorta is cross-clamped, and the heart is arrested with crystalloid cardioplegia. Working through the tricuspid valve, the ventricular septal defect is closed with the patch using a continuous suture technique (Video 11).
During cooling, the stenotic segment of the trachea is transected (Video 6). The short segment stenosis of the trachea (in this case 4 rings) is resected (Video 7). Subsequently, the LPA is translocated anterior to the trachea, and the trachea is reconstructed (Video 8). Intraoperative bronchoscopy is then performed to assess the repair and confirm airway patency. The pericardial flap created is used to wrap the tracheal anastomosis. Subsequently, the endotracheal tube is reinserted and the tracheal airway pressure is temporarily increased to confirm an airtight anastomosis (Video 9).
Video 10. After redirection of the antegrade pulmonary artery flow only to the left pulmonary artery, obvious kinking of the left pulmonary artery is unmasked. Note that the bulging and pulsating left pulmonary artery might have the potential to compress the anterior part of the trachea as well.
3
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343
Video 11. The perimembranous ventricular septal defect is closed with a patch and a continuous 6-0 Prolene suture (Ethicon, Inc, Somerville, NJ). Care is taken to avoid damaging the conduction system and distortion of the chordal attachments of the tricuspid valve.
taneous tracheal repair and repair of intracardiac anomalies, provides encouraging results. Using the reimplantation technique, early mortality in repair of the PAS alone approaches zero, with a 100% LPA patency rate w3, 5x. Results of the repair of short segment tracheal stenosis using resection and end-toend anastomosis are excellent w5, 8–10x. Surgical repair of long-segment congenital tracheal stenosis exhibits higher mortality and morbidity rates. Improved results were achieved with the use of the slide tracheoplasty and the free tracheal autograft technique (Table 1).
Discussion Virtually all patients with PAS have some respiratory symptoms, either due to external tracheal compression that can be corrected by relief of the sling mechanism, or due to severe diffuse tracheal stenosis with complete rings (ring-sling complex) w4x. Currently there is agreement about methods of establishing the diagnosis and sling surgery. The controversy persists regarding the optimal management strategy of longsegment congenital tracheal stenosis w3, 5–7x.
Video 12. The left pulmonary artery is transected at its origin. The site of implantation in the mean pulmonary artery is chosen to approximate the ‘normal’ anatomic origin of the left pulmonary artery. The length of the left pulmonary artery is shortened to prevent kinking, and the anastomosis is performed with a continuous 6-0 Prolene suture (Ethicon, Inc, Somerville, NJ). The opening in the right pulmonary artery is closed with a running suture.
Video 13. The final result of reconstruction of the left pulmonary artery and the trachea is evaluated.
The LPA is transected and anastomosed to the opening created in the MPA at a site that approximates the usual anatomic configuration. The opening in the RPA is closed with a running suture (Video 12). After rewarming, the patient is weaned from bypass and the final outcome of the operation is evaluated (Video 13).
Results The strategy of median sternotomy, CPB, and LPA division and reimplantation into the MPA, with simul4
Clincal status and diagnosis The diagnosis of PAS should be suspected in any child that has respiratory difficulties. Cardiac ECHO is the diagnostic procedure of choice. The color flow Doppler allows precise mapping of the LPA around the distal trachea. This non-invasive procedure can define any coexisting intracardiac abnormalities and is safe to use in critically ill neonates with compromised airways. Spiral computed tomography can be useful in making the diagnosis of tracheal stenosis, if the patient is sufficiently stable for transport w3, 5x. Magnetic resonance imaging is cost inefficient and awkward to use in critically ill patients. Judgment of the severity of tracheal stenosis is based on clinical status and endoscopic findings. The clinical status extends from mild or occasional stridor without respiratory distress, to severe respiratory discomfort with air trapping, pneumonia, and atelectasis. Failure to recognize these symptoms can lead to sudden death in neonates and infants. Rigid bronchoscopy reveals anatomic findings of stenosis including length, Table 1. Reports of simultaneous pulmonary artery sling and tracheal stenosis repair Technique
Number of patients
Mortality (%)
Tracheal autograft w6x Tracheal resection w6, 8–10x Slide tracheoplasty w11–14x
12 24 10
1 (8%) 2 (8%) 2 (20%)
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343 diameter, carina involvement, or tracheobronchial anomalies (tracheobronchus) w15x. Surgical considerations of the pulmonary artery sling repair Once the diagnosis has been made, the defect should be repaired. The application of CPB in a child with arterial oxygen desaturation offers a safe non-compromised environment for reimplantation of the LPA into the MPA, after adequate resection of all residual ductal tissue w3x. Another reason for using CPB is to facilitate the tracheal repair in infants with associated tracheal stenosis. No significant complications related to the use of CPB have been noted w5x. The reimplantation technique w3, 5x takes preference over translocation w8x with distal tracheal resection. There are concerns about translocation, such as the possibility of LPA kinking and anterior compression of the trachea by the LPA w5, 16x (Video 10). In addition, translocation could result in compression of the LPA against the trachea, with a risk of LPA occlusion w16x. Several reports have described excellent long-term patency of implanted left pulmonary arteries w3, 5, 15x. Surgical considerations of tracheal reconstructions Only patients with significant respiratory symptoms should be considered for simultaneous repair of complete tracheal rings. Symptoms are a more important factor than the degree of stenosis itself assessed by bronchoscopy, when deciding whether to perform tracheal surgery w3, 5, 15x. Clinically mild tracheal stenosis requires only observation, and the presence of complete tracheal rings per se is not an indication for tracheoplasty w16, 17x. If tracheal surgery is indicated, the perioperative bronchoscopy is essential to precisely define the degree and length of tracheal stenosis, as the extent of stenosis is not always apparent when viewing the trachea externally. If the stenosed segment is short, it is best treated with resection and end-to-end anastomosis. Resection is generally applied when a stenosis involves -30% to 40% (-8 rings) of the total tracheal length; otherwise excessive anastomotic tension might lead to recurrent stenosis or fatal separation w3, 5, 6, 8–10x. For patients with long segment congenital tracheal stenosis ()8 rings) several surgical techniques have been suggested, but the optimal approach remains controversial. These techniques include rib cartilage
tracheoplasty, pericardial patch tracheoplasty, tracheal autograft plasty, and slide tracheoplasty. The primary concerns include the growth potential of the reconstructed trachea, the incidence of early and late granulation tissue at the repair site, and the long-term functional outcome w3, 5x. Good results were reported with pericardium and with rib cartilage grafts for tracheal repair w5, 6x. Autologous pericardial patch tracheoplasty has the advantage that minimal dissection is required to expose the anterior trachea, thus preserving the lateral blood supply. The pericardial patch is simple to construct, and it can enlarge the entire trachea w6x. The major disadvantage is the potential for patch collapse, the need for prolonged periods of paralysis with ventilatory support, and the formation of obstructing granulation tissue along the suture line that requires repeated endoscopic laser resection w3x. The frequency of postoperative complications requiring reoperation, especially in the presence of pulmonary artery sling, is as high as 50% w5x. The main advantage of the rib cartilage graft technique is its rigidity, which allows the avoidance of prolonged postoperative airway splinting by the endotracheal tube, in contrast to the pericardial patch technique, in which airway splinting is mandatory w18x. However, it is not easy to achieve an airtight suture line using this rigid material. Favorable results for rib cartilage tracheoplasty, with a low rate of postoperative problems and without operative mortality, have been demonstrated w18x. Development of troublesome granulation tissue is frequent w6, 19x. Several surgeons w3, 11–15, 19x have supported the superiority of slide tracheoplasty for long segment stenosis. Slide tracheoplasty doubles the circumference of the trachea, creating a nearly four-fold increase in cross-sectional area. The advantages of this technique are the avoidance of graft materials, tension-free sutures, anatomic and functional trachea, and shorter intensive care unit or hospital stay. Since the trachea is lined with normal ciliated tracheal epithelium, there is little tendency to develop granulation tissue. This technique is even suitable for infants with long-segment tracheal stenosis w3, 15, 19x. For slide tracheoplasty, satisfactory subsequent growth has been experimentally and clinically demonstrated w19x. Excellent results for infants with long segment congenital tracheal stenosis were reported with the free tracheal autograft technique w6, 7x. This technique uses only autologous material for the repair. It is technically easy to perform and is architecturally sound; the autograft is already lined with respiratory epithe5
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343 lium; the cartilage intrinsically maintains its contour; there is potential for growth, and it is readily available. If necessary, this technique can be combined with pericardial augmentation w6x.
Conclusions Repair using a strategy of median sternotomy, CPB, division of the LPA and reimplantation into the MPA, and simultaneous tracheal repair is preferable. However, only patients with significant respiratory symptoms should be considered for simultaneous repair of complete tracheal rings. Symptoms are a more important factor than the degree of stenosis itself, when deciding whether to perform tracheal surgery. The choice of tracheal reconstruction should be guided by the clinical experience of the surgeon. Coexisting intracardiac pathology should be repaired at the same time.
References w1x Potts WJ, Holinger PH, Rosenblum AH. Anomalous left pulmonary artery causing obstruction to right main bronchus: report of a case. J Am Med Assoc 1954;155:1409–1411. w2x Backer CL, Mavroudis C. Congenital heart surgery nomenclature and database project: vascular rings, tracheal stenosis, pectus excavatum. Ann Thorac Surg 2000;69:S308–S318. w3x Fiore AC, Brown JW, Weber TR, Turrentine MW. Surgical treatment of pulmonary artery sling and tracheal stenosis. Ann Thorac Surg 2005;79:38– 46. w4x Berdon WE, Baker DH, Wung JT, Chrispin A, Kozlowski K, de Silva M, Bales P, Alford B. Complete cartilage-ring tracheal stenosis associated with anomalous left pulmonary artery: the ring-sling complex. Radiology 1984;152:57–64. w5x Backer CL, Mavroudis C, Dunham ME, Holinger LD. Pulmonary artery sling: results with median sternotomy, cardiopulmonary bypass, and reimplantation. Ann Thorac Surg 1999;67:1738–1744. w6x Backer CL, Mavroudis C, Gerber ME, Holinger LD. Tracheal surgery in children: an 18-year review of four techniques. Eur J Cardiothorac Surg 2001;19: 777–784.
6
w7x Backer CL, Mavroudis C, Holinger LD. Repair of congenital tracheal stenosis. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2002; 5:173–186. w8x Jonas RA, Spevak PJ, McGill T, Castaneda AR. Pulmonary artery sling: primary repair by tracheal resection in infancy. J Thorac Cardiovasc Surg 1989;97:548–550. w9x Heinemann MK, Ziemer G, Sieverding L, Baden W, Kaulitz R, Luhmer I. Long-segment tracheal resection in infancy utilizing extracorporeal circulation. In: Imai Y, Momma K, editors. Proceedings of the 2nd World Congress of Pediatric Cardiology and Cardiac Surgery. New York: Futura Publishing 1998:711–713. w10x Cotter CS, Jones DT, Nuss RC, Jonas R. Management of distal tracheal stenosis. Arch Otolaryngol Head Neck Surg 1999;125:325–328. w11x Tsang V, Murday A, Gillbe C, Goldstraw P. Slide tracheoplasty for congenital funnel-shaped tracheal stenosis. Ann Thorac Surg 1989;48:632–635. w12x Grillo HC. Slide tracheoplasty for long-segment congenital tracheal stenosis. Ann Thorac Surg 1994;58:613–619. w13x Dayan SH, Dunham ME, Backer CL, Mavroudis C, Holinger LD. Slide tracheoplasty in the management of congenital tracheal stenosis. Ann Otol Rhinol Laryngol 1997;106:914–919. w14x Lang FJ, Hurni M, Monnier P. Long-segment congenital tracheal stenosis: treatment by slidetracheoplasty. J Pediatr Surg 1999;34:1216– 1222. w15x Oshima Y, Yamaguchi M, Yoshimura N, Sato S, Muraji T, Nishijima E, Tsugawa C. Management of pulmonary artery sling associated with tracheal stenosis. Ann Thorac Surg 2008;86:1334–1338. w16x van Son JAM, Hambsch J, Haas GS, Schneider P, Mohr FW. Pulmonary artery sling: reimplantation versus antetracheal translocation. Ann Thorac Surg 1999;68:989–994. w17x Anton-Pacheco JL, Cano I, Comas J, Galletti L, Polo L, Garcia A, Lopez M, Cabezali D. Management of congenital tracheal stenosis in infancy. Eur J Cardiothorac Surg 2006;29:991– 996. w18x Jaquiss RDB, Lusk RP, Spray TL, Huddleston CB. Repair of long-segment tracheal stenosis in infancy. J Thorac Cardiovasc Surg 1995;110: 1504–1512. w19x Kim HK, Kim YT, Sung SW, Park JD, Kang CH, Kim JH, Kim YJ. Management of congenital tracheal stenosis. Eur J Cardiothorac Surg 2004; 25:1065–1071.
Pulmonary artery sling with tracheal stenosis Viktor Hrasˇka*, Joachim Photiadis, Christoph Haun, Ehrenfried Schindler, Martin Schneider, Peter Murin, Boulos Asfour Department of Pediatric Cardiac Surgery, German Pediatric Heart Centre, Asklepios Clinic Sankt Augustin, Arnold Janssen Str. 29, 53757 Sankt Augustin, Germany Pulmonary artery sling (PAS) is a rare congenital heart disease in which the left pulmonary artery (LPA) originates from the right pulmonary artery (RPA) and encircles the distal trachea and right mainstem bronchus as it courses between the trachea and esophagus. Typically, patients with PAS have some respiratory symptoms, either due to external tracheal compression that can be corrected by relief of the sling mechanism, or due to severe diffuse tracheal stenosis with complete rings (ring-sling complex). The diagnosis of PAS is optimally made by echocardiography, while bronchoscopy is the key to the assessment of tracheal stenosis. Diagnosis is indication for surgery. Repair using a strategy of median sternotomy, cardiopulmonary bypass, division of the LPA and reimplantation into the main pulmonary artery (MPA), and simultaneous tracheal repair takes preference. Tracheal repair should be considered only in clinically symptomatic patients. The techniques of free tracheal autograft plasty or slide tracheoplasty offer promising results, and the choice of tracheal reconstruction should be guided by the clinical experience of the surgeon. Coexisting intracardiac pathologies are repaired at the same time. Postoperative care requires close multidisciplinary effort to achieve the best long-term result.
Keywords: Congenital heart disease; Pulmonary artery sling; Ring-sling complex; Tracheal stenosis; Vascular ring
Introduction Pulmonary artery sling (PAS) is a rare congenital condition in which the left pulmonary artery (LPA) originates from the right pulmonary artery (RPA) and encircles the distal trachea and right mainstem bronchus as it courses between the trachea and esophagus to reach the hilum of the left lung w1x. The ligamentum arteriosum or the ductus arteriosus originates from the main pulmonary artery (MPA), and passes anteriorly and superior to the left mainstem bronchus to join the descending thoracic aorta to * Corresponding author. Tel.: q49 2241-249 603; fax: q49 2241249 602 E-mail: [email protected] 䉷 2009 European Association for Cardio-thoracic Surgery
complete the vascular ring w2, 3x. The clinical outcome of patients with PAS depends on the associated tracheal lesions and complex cardiac anomalies. Coexisting diffuse tracheal stenosis, creating a ring-sling complex, is identified in up to 65% of patients with PAS w4x. Typically, stenosis of the trachea is due to complete tracheal rings and ranges from a profound degree of hypoplasia of the entire tracheobronchial tree to a discrete stenosis. Interestingly, despite compression of the tracheobronchial tree by the sling, tracheomalacia is usually not a feature. Congenital heart defects are found in 50% of PAS cases, the most common being atrial and ventricular septal defects, patent ductus arteriosus, left superior vena cava, and tetralogy of Fallot w5x. 1
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343 Current treatment protocol Treatment of patients with PAS requires close collaboration of pediatric cardiac surgeons and their medical counterparts. Diagnosis of PAS is optimally made using echocardiography, as it is rapid and non-invasive. All infants should undergo bronchoscopy to rule out tracheal stenosis secondary to congenital complete tracheal rings. Diagnosis is indication for surgery. Repair using a strategy of median sternotomy, cardiopulmonary bypass (CPB), LPA division and reimplantation into the MPA, and simultaneous tracheal repair takes preference. Tracheal repair should be considered only in clinically symptomatic patients. Coexisting intracardiac pathology is repaired or palliated at the same time w3, 5x. The postoperative care of these patients requires close vigilance by pediatric intensivists, anesthesiologists, and pediatric cardiac surgeons. The management of the reconstructed trachea requires close collaboration among these specialities in order to achieve the best long-term result w6, 7x
Surgical technique
Exposure of the stenotic trachea is performed by dissecting the space between the aorta and superior vena cava (SVC) (Videos 3 and 4). CPB is commenced (Video 5). Being on CPB provides complete freedom to manipulate the pulmonary arteries and respiratory support for the tracheal repair. During this time frame the endotracheal tube might be removed, and then either rigid or fiberoptic bronchoscopy is performed to confirm the extent and degree of stenosis. Needles can be placed through the trachea, using bronchoscopic visualization, to delineate the extent of stenosis externally.
Video 2. Extensive dissection and mobilization of the right pulmonary artery and the origin of the left pulmonary artery are carried out.
Repair of PAS with resection of the trachea and closure of the VSD in an infant In this specific symptomatic infant, the diagnosis was established by ECHO and confirmed by angiography and tracheography (Video 1). Intraoperative bronchoscopy demonstrated short-segment tracheal stenosis with complete tracheal rings involving the distal part of the trachea. Median sternotomy is performed. The thymus is completely resected, and the pericardium is harvested, and pretreated in glutaraldehyde for further use. The aorta and the pulmonary artery are dissected free, and the ductus arteriosus (or ligamentum) is ligated and divided. The LPA is identified as originating from the superior aspect of the RPA (Video 2).
Video 1. Diagnosis was made by ECHO and angiography.
2
Video 3. During dissection of the trachea, care is taken to avoid damaging the lateral tracheal blood supply, especially along the distal half of the trachea and at the level of the carina. The left pulmonary artery is carefully dissected away from the posterior trachea and anterior esophagus. Care is taken to avoid injury to the recurrent laryngeal nerve. Finally, the left pulmonary artery is dissected circumferentially up to the left hilar branches. This usually requires entering the left pleural space.
Video 4. The left pulmonary artery encircles and compresses the distal area of the trachea and right mainstem bronchus.
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343
Video 5. The standard techniques of cardiopulmonary bypass, including bicaval cannulation and moderate hypothermia (32 8C), are used. A left ventricular vent is inserted through the entrance of the right pulmonary veins.
Video 6. The trachea is transected at the narrowest point. The left pulmonary artery is brought anterior above the carina. The very distal complete ring above the carina is resected first. Note the close relationship of the bronchus suis and the carina.
Video 8. Using a continuous 6-0 polyglyconate suture, end-to-end anastomosis is fashioned. Care is taken to avoid the placement of suture material in the tracheal mucosa, in order to minimize granulation tissue formation.
Video 9. A pedicled pericardial patch is harvested to separate the tracheal anastomosis from the mediastinum. Care is taken to stay away from the phrenic nerve. The mediastinum is filled with saline, and the patient is ventilated to a peak airway pressure of 35–40 cm H2O to assess the anastomosis for leaks.
The possibility of kinking of the LPA and compression of the trachea by the LPA are evaluated. Usually the takeoff of the LPA is at an angle of nearly 1808, and that may cause proximal kinking. The decision is made in favor of translocation of the LPA (Video 10).
Video 7. Gradually, the remaining stenotic rings (3 rings) are resected to achieve an optimal lumen of the trachea. Note the high mobility of the proximal segment of the trachea as a prerequisite of tension free anastomosis.
The aorta is cross-clamped, and the heart is arrested with crystalloid cardioplegia. Working through the tricuspid valve, the ventricular septal defect is closed with the patch using a continuous suture technique (Video 11).
During cooling, the stenotic segment of the trachea is transected (Video 6). The short segment stenosis of the trachea (in this case 4 rings) is resected (Video 7). Subsequently, the LPA is translocated anterior to the trachea, and the trachea is reconstructed (Video 8). Intraoperative bronchoscopy is then performed to assess the repair and confirm airway patency. The pericardial flap created is used to wrap the tracheal anastomosis. Subsequently, the endotracheal tube is reinserted and the tracheal airway pressure is temporarily increased to confirm an airtight anastomosis (Video 9).
Video 10. After redirection of the antegrade pulmonary artery flow only to the left pulmonary artery, obvious kinking of the left pulmonary artery is unmasked. Note that the bulging and pulsating left pulmonary artery might have the potential to compress the anterior part of the trachea as well.
3
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343
Video 11. The perimembranous ventricular septal defect is closed with a patch and a continuous 6-0 Prolene suture (Ethicon, Inc, Somerville, NJ). Care is taken to avoid damaging the conduction system and distortion of the chordal attachments of the tricuspid valve.
taneous tracheal repair and repair of intracardiac anomalies, provides encouraging results. Using the reimplantation technique, early mortality in repair of the PAS alone approaches zero, with a 100% LPA patency rate w3, 5x. Results of the repair of short segment tracheal stenosis using resection and end-toend anastomosis are excellent w5, 8–10x. Surgical repair of long-segment congenital tracheal stenosis exhibits higher mortality and morbidity rates. Improved results were achieved with the use of the slide tracheoplasty and the free tracheal autograft technique (Table 1).
Discussion Virtually all patients with PAS have some respiratory symptoms, either due to external tracheal compression that can be corrected by relief of the sling mechanism, or due to severe diffuse tracheal stenosis with complete rings (ring-sling complex) w4x. Currently there is agreement about methods of establishing the diagnosis and sling surgery. The controversy persists regarding the optimal management strategy of longsegment congenital tracheal stenosis w3, 5–7x.
Video 12. The left pulmonary artery is transected at its origin. The site of implantation in the mean pulmonary artery is chosen to approximate the ‘normal’ anatomic origin of the left pulmonary artery. The length of the left pulmonary artery is shortened to prevent kinking, and the anastomosis is performed with a continuous 6-0 Prolene suture (Ethicon, Inc, Somerville, NJ). The opening in the right pulmonary artery is closed with a running suture.
Video 13. The final result of reconstruction of the left pulmonary artery and the trachea is evaluated.
The LPA is transected and anastomosed to the opening created in the MPA at a site that approximates the usual anatomic configuration. The opening in the RPA is closed with a running suture (Video 12). After rewarming, the patient is weaned from bypass and the final outcome of the operation is evaluated (Video 13).
Results The strategy of median sternotomy, CPB, and LPA division and reimplantation into the MPA, with simul4
Clincal status and diagnosis The diagnosis of PAS should be suspected in any child that has respiratory difficulties. Cardiac ECHO is the diagnostic procedure of choice. The color flow Doppler allows precise mapping of the LPA around the distal trachea. This non-invasive procedure can define any coexisting intracardiac abnormalities and is safe to use in critically ill neonates with compromised airways. Spiral computed tomography can be useful in making the diagnosis of tracheal stenosis, if the patient is sufficiently stable for transport w3, 5x. Magnetic resonance imaging is cost inefficient and awkward to use in critically ill patients. Judgment of the severity of tracheal stenosis is based on clinical status and endoscopic findings. The clinical status extends from mild or occasional stridor without respiratory distress, to severe respiratory discomfort with air trapping, pneumonia, and atelectasis. Failure to recognize these symptoms can lead to sudden death in neonates and infants. Rigid bronchoscopy reveals anatomic findings of stenosis including length, Table 1. Reports of simultaneous pulmonary artery sling and tracheal stenosis repair Technique
Number of patients
Mortality (%)
Tracheal autograft w6x Tracheal resection w6, 8–10x Slide tracheoplasty w11–14x
12 24 10
1 (8%) 2 (8%) 2 (20%)
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343 diameter, carina involvement, or tracheobronchial anomalies (tracheobronchus) w15x. Surgical considerations of the pulmonary artery sling repair Once the diagnosis has been made, the defect should be repaired. The application of CPB in a child with arterial oxygen desaturation offers a safe non-compromised environment for reimplantation of the LPA into the MPA, after adequate resection of all residual ductal tissue w3x. Another reason for using CPB is to facilitate the tracheal repair in infants with associated tracheal stenosis. No significant complications related to the use of CPB have been noted w5x. The reimplantation technique w3, 5x takes preference over translocation w8x with distal tracheal resection. There are concerns about translocation, such as the possibility of LPA kinking and anterior compression of the trachea by the LPA w5, 16x (Video 10). In addition, translocation could result in compression of the LPA against the trachea, with a risk of LPA occlusion w16x. Several reports have described excellent long-term patency of implanted left pulmonary arteries w3, 5, 15x. Surgical considerations of tracheal reconstructions Only patients with significant respiratory symptoms should be considered for simultaneous repair of complete tracheal rings. Symptoms are a more important factor than the degree of stenosis itself assessed by bronchoscopy, when deciding whether to perform tracheal surgery w3, 5, 15x. Clinically mild tracheal stenosis requires only observation, and the presence of complete tracheal rings per se is not an indication for tracheoplasty w16, 17x. If tracheal surgery is indicated, the perioperative bronchoscopy is essential to precisely define the degree and length of tracheal stenosis, as the extent of stenosis is not always apparent when viewing the trachea externally. If the stenosed segment is short, it is best treated with resection and end-to-end anastomosis. Resection is generally applied when a stenosis involves -30% to 40% (-8 rings) of the total tracheal length; otherwise excessive anastomotic tension might lead to recurrent stenosis or fatal separation w3, 5, 6, 8–10x. For patients with long segment congenital tracheal stenosis ()8 rings) several surgical techniques have been suggested, but the optimal approach remains controversial. These techniques include rib cartilage
tracheoplasty, pericardial patch tracheoplasty, tracheal autograft plasty, and slide tracheoplasty. The primary concerns include the growth potential of the reconstructed trachea, the incidence of early and late granulation tissue at the repair site, and the long-term functional outcome w3, 5x. Good results were reported with pericardium and with rib cartilage grafts for tracheal repair w5, 6x. Autologous pericardial patch tracheoplasty has the advantage that minimal dissection is required to expose the anterior trachea, thus preserving the lateral blood supply. The pericardial patch is simple to construct, and it can enlarge the entire trachea w6x. The major disadvantage is the potential for patch collapse, the need for prolonged periods of paralysis with ventilatory support, and the formation of obstructing granulation tissue along the suture line that requires repeated endoscopic laser resection w3x. The frequency of postoperative complications requiring reoperation, especially in the presence of pulmonary artery sling, is as high as 50% w5x. The main advantage of the rib cartilage graft technique is its rigidity, which allows the avoidance of prolonged postoperative airway splinting by the endotracheal tube, in contrast to the pericardial patch technique, in which airway splinting is mandatory w18x. However, it is not easy to achieve an airtight suture line using this rigid material. Favorable results for rib cartilage tracheoplasty, with a low rate of postoperative problems and without operative mortality, have been demonstrated w18x. Development of troublesome granulation tissue is frequent w6, 19x. Several surgeons w3, 11–15, 19x have supported the superiority of slide tracheoplasty for long segment stenosis. Slide tracheoplasty doubles the circumference of the trachea, creating a nearly four-fold increase in cross-sectional area. The advantages of this technique are the avoidance of graft materials, tension-free sutures, anatomic and functional trachea, and shorter intensive care unit or hospital stay. Since the trachea is lined with normal ciliated tracheal epithelium, there is little tendency to develop granulation tissue. This technique is even suitable for infants with long-segment tracheal stenosis w3, 15, 19x. For slide tracheoplasty, satisfactory subsequent growth has been experimentally and clinically demonstrated w19x. Excellent results for infants with long segment congenital tracheal stenosis were reported with the free tracheal autograft technique w6, 7x. This technique uses only autologous material for the repair. It is technically easy to perform and is architecturally sound; the autograft is already lined with respiratory epithe5
V. Hrasˇka et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2008.003343 lium; the cartilage intrinsically maintains its contour; there is potential for growth, and it is readily available. If necessary, this technique can be combined with pericardial augmentation w6x.
Conclusions Repair using a strategy of median sternotomy, CPB, division of the LPA and reimplantation into the MPA, and simultaneous tracheal repair is preferable. However, only patients with significant respiratory symptoms should be considered for simultaneous repair of complete tracheal rings. Symptoms are a more important factor than the degree of stenosis itself, when deciding whether to perform tracheal surgery. The choice of tracheal reconstruction should be guided by the clinical experience of the surgeon. Coexisting intracardiac pathology should be repaired at the same time.
References w1x Potts WJ, Holinger PH, Rosenblum AH. Anomalous left pulmonary artery causing obstruction to right main bronchus: report of a case. J Am Med Assoc 1954;155:1409–1411. w2x Backer CL, Mavroudis C. Congenital heart surgery nomenclature and database project: vascular rings, tracheal stenosis, pectus excavatum. Ann Thorac Surg 2000;69:S308–S318. w3x Fiore AC, Brown JW, Weber TR, Turrentine MW. Surgical treatment of pulmonary artery sling and tracheal stenosis. Ann Thorac Surg 2005;79:38– 46. w4x Berdon WE, Baker DH, Wung JT, Chrispin A, Kozlowski K, de Silva M, Bales P, Alford B. Complete cartilage-ring tracheal stenosis associated with anomalous left pulmonary artery: the ring-sling complex. Radiology 1984;152:57–64. w5x Backer CL, Mavroudis C, Dunham ME, Holinger LD. Pulmonary artery sling: results with median sternotomy, cardiopulmonary bypass, and reimplantation. Ann Thorac Surg 1999;67:1738–1744. w6x Backer CL, Mavroudis C, Gerber ME, Holinger LD. Tracheal surgery in children: an 18-year review of four techniques. Eur J Cardiothorac Surg 2001;19: 777–784.
6
w7x Backer CL, Mavroudis C, Holinger LD. Repair of congenital tracheal stenosis. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2002; 5:173–186. w8x Jonas RA, Spevak PJ, McGill T, Castaneda AR. Pulmonary artery sling: primary repair by tracheal resection in infancy. J Thorac Cardiovasc Surg 1989;97:548–550. w9x Heinemann MK, Ziemer G, Sieverding L, Baden W, Kaulitz R, Luhmer I. Long-segment tracheal resection in infancy utilizing extracorporeal circulation. In: Imai Y, Momma K, editors. Proceedings of the 2nd World Congress of Pediatric Cardiology and Cardiac Surgery. New York: Futura Publishing 1998:711–713. w10x Cotter CS, Jones DT, Nuss RC, Jonas R. Management of distal tracheal stenosis. Arch Otolaryngol Head Neck Surg 1999;125:325–328. w11x Tsang V, Murday A, Gillbe C, Goldstraw P. Slide tracheoplasty for congenital funnel-shaped tracheal stenosis. Ann Thorac Surg 1989;48:632–635. w12x Grillo HC. Slide tracheoplasty for long-segment congenital tracheal stenosis. Ann Thorac Surg 1994;58:613–619. w13x Dayan SH, Dunham ME, Backer CL, Mavroudis C, Holinger LD. Slide tracheoplasty in the management of congenital tracheal stenosis. Ann Otol Rhinol Laryngol 1997;106:914–919. w14x Lang FJ, Hurni M, Monnier P. Long-segment congenital tracheal stenosis: treatment by slidetracheoplasty. J Pediatr Surg 1999;34:1216– 1222. w15x Oshima Y, Yamaguchi M, Yoshimura N, Sato S, Muraji T, Nishijima E, Tsugawa C. Management of pulmonary artery sling associated with tracheal stenosis. Ann Thorac Surg 2008;86:1334–1338. w16x van Son JAM, Hambsch J, Haas GS, Schneider P, Mohr FW. Pulmonary artery sling: reimplantation versus antetracheal translocation. Ann Thorac Surg 1999;68:989–994. w17x Anton-Pacheco JL, Cano I, Comas J, Galletti L, Polo L, Garcia A, Lopez M, Cabezali D. Management of congenital tracheal stenosis in infancy. Eur J Cardiothorac Surg 2006;29:991– 996. w18x Jaquiss RDB, Lusk RP, Spray TL, Huddleston CB. Repair of long-segment tracheal stenosis in infancy. J Thorac Cardiovasc Surg 1995;110: 1504–1512. w19x Kim HK, Kim YT, Sung SW, Park JD, Kang CH, Kim JH, Kim YJ. Management of congenital tracheal stenosis. Eur J Cardiothorac Surg 2004; 25:1065–1071.
