Pediatr Surg Int (2014) 30:113–117 DOI 10.1007/s00383-013-3435-0
TECHNICAL INNOVATION
Technical innovation in minimally invasive repair of pectus excavatum Michal Rygl • M. Vyhnanek • A. Kucera V. Mixa • M. Kyncl • J. Snajdauf
•
Accepted: 1 November 2013 / Published online: 30 November 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract The aim of study was to introduce technical innovation of MIRPE which reduces the risk of cardiac injury. Modification of MIRPE method with semiflexible thoracoscope and sternum elevating technique has been used. Volkmann bone hook has been inserted percutaneously to the sternum. The hook elevates the sternum forward and enlarges the retrosternal space for safer passage of thoracoscopically guided introducer. Using semiflexible thoracoscope allows better view from various angles via one site of insertion. During the period 2005–2012, the MIRPE was performed on 29 girls and 151 boys; the mean age at the time of surgery was 15.9 years (range 13–18.7 years). The mean Haller index was 4.7 (range M. Rygl (&) M. Vyhnanek A. Kucera J. Snajdauf Department of Pediatric Surgery, 2nd Faculty of Medicine and Teaching Hospital in Motol, Charles University in Prague, ´ valu 84, 15000 Prague 5, Czech Republic VU e-mail: [email protected] M. Vyhnanek e-mail: [email protected] A. Kucera e-mail: [email protected] J. Snajdauf e-mail: [email protected] V. Mixa Department of Anaesthesia and Intensive Care Medicine, 2nd Faculty of Medicine and Teaching Hospital in Motol, ´ valu 84, 15006 Prague 5, Charles University in Prague, V U Czech Republic e-mail: [email protected] M. Kyncl Department of Imaging Methods, 2nd Faculty of Medicine and Teaching Hospital in Motol, Charles University in Prague, ´ valu 84, 15006 Prague 5, Czech Republic VU e-mail: [email protected]
2.7–20.5). The most common complication was pneumothorax (3.3 %) and the incidence of bar displacement was 2 %. The most serious complication was cardiac perforation when inserting Lorenz introducer. This occurred in a 16-year-old girl; she required urgent sternotomy with right atrial repair and recovered well. External elevation of sternum with the hook was used since this case. Subsequent 113 patients underwent surgery without any serious complications. Technical innovation using semiflexible thoracoscope and hook elevation of the sternum reduces the risk of cardiac injury. The hook opens the anterior mediastinum space effectively and makes the following dissection relatively safe and straightforward. Keywords Pectus excavatum Minimally invasive repair of pectus excavatum Semiflexible thoracoscope Wolkmann bone hook Sternum elevating technique
Introduction Since original report by Nuss et al. [1] in 1998 minimally invasive repair of pectus excavatum (MIRPE) has become worldwide standard procedure for correction of pectus excavatum (PE). Subsequent technical and design modifications have included routine thoracoscopy, the use of an introducer/dissector for creating the substernal tunnel, and routine use of a lateral stabilizer and sutures around the bar and underlying rib to prevent bar displacement [2, 3]. Cardiac injury is the most feared complication of the method [4]. The true incidence of this complication is unknown and probably more frequent than generally believed. About 10 cases of cardiac perforation are reported in literature [4–9]. Two of them were fatal. Bouchard
123
114
Fig. 1 Semiflexible fiberoptic thoracoscope provides optimal visualization from various angles via one site of insertion with low interference of introducer
Pediatr Surg Int (2014) 30:113–117
Fig. 2 An assistant standing at the patient’s left side inserts percutaneously Wolkmann bone hook to the distal sternum and holds the hook up and creates sufficient space between the sternum and heart. The hook opens the anterior mediastinum space effectively and makes the following dissection relatively safe and straightforward
et al. published the most comprehensive paper which presents four severe cardiac injuries that occurred in patients who underwent MIRPE. These complications occurred in different clinical settings, namely in a placement of introducer, in bar removal in patients who had surgery previously. One of these patients died [4]. To prevent this complication, we developed a new simple sternum elevating technique that reduces the risks of cardiac and pericardial injury. The report presents two novel technical innovations of MIRPE which reduce the risk of cardiac injury and review of the corresponding literature.
Materials and methods The operation was performed under general anesthesia with selective pulmonary ventilation using double lumen tracheal tube (Silbroncho, Fuji Systems Corporation, Japan). The MIRPE procedure starts with bilateral transverse thoracic incisions, which are positioned posterior to the anterior axillary line. A subcutaneous tunnel is created from each incision to the pectus ridge. A semiflexible thoracoscope (F-160, Olympus Medical Systems, Tokyo, Japan) is inserted into the pleural cavity through the third small incision on the right side (Fig. 1). An assistant standing at the patient’s left side inserts Wolkmann bone hook (Fig. 2) to the distal sternum percutaneously, and holds the hook up thus creating sufficient space between the sternum and heart. In thoracoscopic view, the sternum is seen to be well elevated and away from the heart (Fig. 3a without the sternum lift; Fig. 3b with sternum lift). The enlarged retrosternal space enables safer passage of thoracoscopically guided introducer. The introducer is passed
123
Fig. 3 In thoracoscopic view, the sternum is seen to be well elevated and away from the heart (a without the sternum lift, b with sternum lift)
through the already widened mediastinum space toward left thoracic cavity. Following this process, the procedure continues as described previously. The concave deformity of the pectus excavatum is corrected after a 180 rotation of the bar and fixation of stabilizer (the introducer, bar,
Pediatr Surg Int (2014) 30:113–117 Table 1 Modification of MIRPE reducing the risk of cardiac injury reported in the literature
115
Author
Extra device
Extra incision
Thoracoscopy
Patients
Tedde et al. [16]
29 Langenbeck
No
Right
25
Takagi et al. [10]
Sternal elevator
No
Right
61
Ohno et al. [15]
No
No
Bilateral
35
Yoon et al. [17]
Kent retractor
Puncture
Right
44
Johnson et al. [18]
Sternal lift
Yes
Right
–
Haecker et al. [20]
Vacuum bell
No
Right
55
Hendrickson et al. [12]
Endo-kittner
No
Left
51
St Peter et al. [19]
No
Yes
No
307
Zallen et al. [13]
70 scope
No
Bilateral
stabilizer are products of Lorenz Surgical Inc, Jacksonville, FL, USA).
Results During the period 2005–2012, the MIRPE was performed in 29 girls and 151 boys; the mean age at the time of surgery was 15.9 years (range 13–18.7 years). The mean Haller index was 4.7 (range 2.7–20.5). The most common complication was pneumothorax (3.3 %) and the less common problems included atelectasis (1.1 %), fluidothorax (0.6 %), and lung injury (0.6 %). Wound complications were abscess (3.3 %), dehiscence (0.6 %), and seroma (0.6 %). The incidence of bar displacement was 2 %. The most serious complication was cardiac perforation when inserting Lorenz introducer. This occurred in a 16-year-old girl; she required urgent sternotomy with right atrial repair and recovered well. External elevation of sternum with a hook was used since this case. Subsequent 113 patients underwent surgery without any serious complications.
Discussion The MIRPE procedure is distinctly superior to traditional open procedure because of minimal surgical trauma without costal cartilage resection. However, since the introducer passes through the limited space between the heart and depressed sternum, the technique carries a risk of lifethreatening complications [10]. Generally, there are three methods to reduce the risk of cardiac injury during MIRPE: thoracoscopy, sternum elevating technique and additional incision (Table 1). Our presented innovation uses semiflexible thoracoscope and hook elevation of the sternum (Figs. 1, 2, 3). Semiflexible fiberoptic thoracoscope provides optimal visualization with low interference of introducer. Wolkmann bone hook (Fig. 2) lifts up the sternum and enlarges the retrosternal space for safer passage of the introducer.
52
Percutaneous insertion of the hook without additional incision, without any extended dissection or trauma to intercostals muscles and mediastinal tissue is easy and reproducible. Corticalis of the sternal bone is strong enough to hold the Wolkmann hook when elevating the anterior chest wall. The clear visualization with semiflexible thoracoscope and elevated sternum with hook are not only safer but also time-saving procedures. Thoracoscopy is an elementary method to prevent cardiac or pulmonary injury. The passage of the introducer into the anterior mediastinum is monitored. However, the field of vision of this procedure could be limited, especially at the point where the deeply depressed sternum and right atrium remain in close contact. To clearly visualize the pericardium and heart, various procedures are used: rightsided thoracoscopy [11], left-sided thoracoscopy [12], bilateral thoracoscopy [13–15] and upper position of thoracoscope. However, the cases of cardiac perforation have occurred despite their use. Right-sided thoracoscopy with scopes with an angle of vision of 30° is most widely used at centers worldwide. Saxena et al. [11] recommended the scopes with an angle of vision of 30° and they speculated that investing in scopes of different sizes such as 45° and 70° does not offer any added advantages to the procedure if the port site is properly selected. Conversely, Zallen et al. [13] have found that the angled scope allows optimal visualization of the mediastinum and the rib cage. They recommend using a 28-cm-long, 70°, 5-mm scope which works better for placing the bar and the wires to secure the bar. Palmer et al. [14] advocated bilateral thoracoscopic repair of pectus excavatum with left-to-right mediastinal dissection which is a safe alternative to the traditional approach, as it allows a more complete visualization of the mediastinum and eliminates the need for additional safety measures such as subxiphoid dissection and elevation. We recommend using semiflexible fiberoptic thoracoscope (F-160, Olympus Medical Systems, Tokyo, Japan) having a solid body and a flexible terminal section (Fig. 1), which provide optimal visualization from various angles
123
116
via one site of insertion. The advantage of flexible thoracoscope is particularly in case of deep deformity, in case of marked displacement of the hearth, in case of high position of diaphragm and in case of interference of introducer. In addition to thoracoscopy, some techniques of mediastinal dissection have been designed to reduce the risk of cardiac injury (Table 1). Hendrickson et al. [12] described modification to the Nuss procedure using the left hemithorax for thoracoscopy rather than the right. The heart is usually the first structure identified and can be kept in the operative field at all times. The second 5-mm port is placed in the inferior aspect of the left vertical incision to accommodate an Endo-kittner, which allows accurate and detailed dissection of the retrosternal area. Once the mediastinal dissection is complete, the Nuss bar introducer is inserted and advanced across the mediastinum under direct visualization. Left thoracoscopy ensures that the heart is under direct visualization during the entire procedure, and the use of the Endo-kittner dissector permits accurate and detailed mediastinal dissection. Authors postulate that other methods to ensure safe substernal dissection such as using a subxiphoid incision are unnecessary. Ohno et al. [15] inserted the introducer into the pleura between the sternum and thymus instead of the thoracic depression. After the introducer reaches the internal cranial position of the left nipple, the thoracoscope is shifted to left and the introducer is subsequently guided down to the corresponding intercostal space. The authors emphasize that their modification allows continual observation of the tip of introducer and thus reduces the risk of fatal injury during insertion across the deep depression. On the other hand, their procedure required more extensive dissection in anterior mediastinum and bilateral thoracoscopy, both of which can increase the incidence of minor complications. Other authors added various sternum elevating techniques, lifting the sternum with elevator, retractor, lift, vacuum bell with or without additional subxiphoid incision to the above-mentioned procedures (Table 1). Tedde et al. described technical modification of the Nuss procedure on a series of 25 patients. They positioned two Langenbeck retractors inside both hemithoraces and pulled them upwards. They speculated that the retractors pull the chest wall up while the heart is moved down by its weight creating more space between the sternum and the pericardial sac [16]. The retractors are inserted via the same incision and via the same subcutaneous channel that is created for introducer. Nevertheless, insertion of retractors causes a larger laceration of intercostal muscles and thus brings some more risk for stability of the bar and overgrowth of local tissue.
123
Pediatr Surg Int (2014) 30:113–117
Takagi et al. [10] reported innovation with a newly design sternum elevator, that is now commercially available. No extra skin incision is needed, the elevator is inserted from the right, in the same point as introducer. The elevator has the same curvature as a Nuss introducer and the same site of insertion but the author postulates that the interference is minimal. Yoon et al. [17] used the so-called Crane technique for sternal elevation in adolescent and adult. The wire is sutured onto the sternum and the sternum is elevated by pulling the wire up with the Kent retractor. They stress that this technique minimizes mediastinal injury during passing and rotating the bar by increasing the anterior mediastinal space. Johnson et al. [18] developed a novel sternal lift system and they believed that it will help eliminate intraoperative cardiac perforation in the Nuss procedure. They also speculate that this technique will reduce the duration of the operation and other more common complications, and it is feasible even in patients with severe pectus excavatum with Haller index above 7. Positioning of elevator requires additional subxiphoid incision which is the weakness of this method. St Peter et al. [19] have used a subxiphoid incision to allow finger guidance to protect the mediastinum which obviates the need for thoracoscopy or any other elevating device. The subxiphoid-guided technique is a simple, safe, and reproducible method for the MIRPE that obviates the need for thoracoscopy. The subxiphoid incision, however, adds an additional scar to the anterior chest wall that is sometimes cosmetically unacceptable to the indications for PE repair that is often predominantly cosmetic. Haecker et al. evaluated the routine use of the vacuum bell for elevating the sternum during MIRPE in 50 patients. The use of the vacuum bell led to a clear elevation of the sternum as confirmed by thoracoscopy. Advancement of the pectus introducer and placement of the pectus bar were safe, successful, and uneventful in all patients. No cardiac and/or pericardial lesion as well as no lesion of the mammary vessels was noted [20].
Conclusion MIRPE procedure is an effective method with elegant cosmetic results. Modifications of the original method help decrease the complication rate. Technical innovation using semiflexible thoracoscope and hook elevation of the sternum reduces the risk of cardiac injury. The hook opens the anterior mediastinum space effectively and makes the following dissection relatively safe and straightforward. Semiflexible fiberoptic thoracoscope provides optimal
Pediatr Surg Int (2014) 30:113–117
visualization from various angles via one site of insertion with low interference of introducer. Acknowledgments Authors would like to thank Ms Jana Kalousova´ M.D. for expert consultation. Conflict of interest of interest.
The authors declare that they have no conflict
References 1. Nuss D, Kelly RE Jr, Croitoru DP, Katz ME (1998) A 10-year review of a minimally invasive technique for the correction of pectus excavatum. J Pediatr Surg 33:545–552 2. Nuss D (2008) Minimally invasive surgical repair of pectus excavatum. Semin Pediatr Surg 17:209–217 3. Hebra A, Gauderer MW, Tagge EP, Adamson WT, Othersen HB Jr (2001) A simple technique for preventing bar displacement with the Nuss repair of pectus excavatum. J Pediatr Surg 36:1266–1268 4. Bouchard S, Hong AR, Gilchrist BF, Kuenzler KA (2009) Catastrophic cardiac injuries encountered during the minimally invasive repair of pectus excavatum. Semin Pediatr Surg 18:66–72 5. Tedde ML, Campos JR, Das-Neves-Pereira JC, Abrao FC, Jatene FB (2011) The search for stability: bar displacement in three series of pectus excavatum patients treated with the Nuss technique. Clinics (Sao Paulo) 66:1743–1746 6. Becmeur F, Ferreira CG, Haecker FM, Schneider A, Lacreuse I (2011) Pectus excavatum repair according to Nuss: is it safe to place a retrosternal bar by a transpleural approach, under thoracoscopic vision? J Laparoendosc Adv Surg Tech A 21:757–761 7. Castellani C, Schalamon J, Saxena AK, Hoellwarth ME (2008) Early complications of the Nuss procedure for pectus excavatum: a prospective study. Pediatr Surg Int 24:659–666 8. Moss RL, Albanese CT, Reynolds M (2001) Major complications after minimally invasive repair of pectus excavatum: case reports. J Pediatr Surg 36:155–158
117 9. Gips H, Zaitsev K, Hiss J (2008) Cardiac perforation by a pectus bar after surgical correction of pectus excavatum: case report and review of the literature. Pediatr Surg Int 24:617–620 10. Takagi S, Oyama T, Tomokazu N et al (2012) A new sternum elevator reduces severe complications during minimally invasive repair of the pectus excavatum. Pediatr Surg Int 28:623–626 11. Saxena AK, Castellani C, Hollwarth ME (2007) Surgical aspects of thoracoscopy and efficacy of right thoracoscopy in minimally invasive repair of pectus excavatum. J Thorac Cardiovasc Surg 133:1201–1205 12. Hendrickson RJ, Bensard DD, Janik JS, Partrick DA (2005) Efficacy of left thoracoscopy and blunt mediastinal dissection during the Nuss procedure for pectus excavatum. J Pediatr Surg 40:1312–1314 13. Zallen GS, Glick PL (2004) Miniature access pectus excavatum repair: lessons we have learned. J Pediatr Surg 39:685–689 14. Palmer B, Yedlin S, Kim S (2007) Decreased risk of complications with bilateral thoracoscopy and left-to-right mediastinal dissection during minimally invasive repair of pectus excavatum. Eur J Pediatr Surg 17:81–83 15. Ohno K, Nakamura T, Azuma T et al (2009) Modification of the Nuss procedure for pectus excavatum to prevent cardiac perforation. J Pediatr Surg 44:2426–2430 16. Tedde ML, de Campos JR, Wihlm JM, Jatene FB (2012) The Nuss procedure made safer: an effective and simple sternal elevation manoeuvre. Eur J Cardiothorac Surg 42:890–891 17. Yoon YS, Kim HK, Choi YS et al (2010) A modified Nuss procedure for late adolescent and adult pectus excavatum. World J Surg 34:1475–1480 18. Johnson WR, Fedor D, Singhal S (2013) A novel approach to eliminate cardiac perforation in the Nuss procedure. Ann Thorac Surg 95:1109–1111 19. St Peter SD, Sharp SW, Ostlie DJ et al (2010) Use of a subxiphoid incision for pectus bar placement in the repair of pectus excavatum. J Pediatr Surg 45:1361–1364 20. Haecker FM, Sesia SB (2012) Intraoperative use of the vacuum bell for elevating the sternum during the Nuss procedure. J Laparoendosc Adv Surg Tech A 22:934–936
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TECHNICAL INNOVATION
Technical innovation in minimally invasive repair of pectus excavatum Michal Rygl • M. Vyhnanek • A. Kucera V. Mixa • M. Kyncl • J. Snajdauf
•
Accepted: 1 November 2013 / Published online: 30 November 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract The aim of study was to introduce technical innovation of MIRPE which reduces the risk of cardiac injury. Modification of MIRPE method with semiflexible thoracoscope and sternum elevating technique has been used. Volkmann bone hook has been inserted percutaneously to the sternum. The hook elevates the sternum forward and enlarges the retrosternal space for safer passage of thoracoscopically guided introducer. Using semiflexible thoracoscope allows better view from various angles via one site of insertion. During the period 2005–2012, the MIRPE was performed on 29 girls and 151 boys; the mean age at the time of surgery was 15.9 years (range 13–18.7 years). The mean Haller index was 4.7 (range M. Rygl (&) M. Vyhnanek A. Kucera J. Snajdauf Department of Pediatric Surgery, 2nd Faculty of Medicine and Teaching Hospital in Motol, Charles University in Prague, ´ valu 84, 15000 Prague 5, Czech Republic VU e-mail: [email protected] M. Vyhnanek e-mail: [email protected] A. Kucera e-mail: [email protected] J. Snajdauf e-mail: [email protected] V. Mixa Department of Anaesthesia and Intensive Care Medicine, 2nd Faculty of Medicine and Teaching Hospital in Motol, ´ valu 84, 15006 Prague 5, Charles University in Prague, V U Czech Republic e-mail: [email protected] M. Kyncl Department of Imaging Methods, 2nd Faculty of Medicine and Teaching Hospital in Motol, Charles University in Prague, ´ valu 84, 15006 Prague 5, Czech Republic VU e-mail: [email protected]
2.7–20.5). The most common complication was pneumothorax (3.3 %) and the incidence of bar displacement was 2 %. The most serious complication was cardiac perforation when inserting Lorenz introducer. This occurred in a 16-year-old girl; she required urgent sternotomy with right atrial repair and recovered well. External elevation of sternum with the hook was used since this case. Subsequent 113 patients underwent surgery without any serious complications. Technical innovation using semiflexible thoracoscope and hook elevation of the sternum reduces the risk of cardiac injury. The hook opens the anterior mediastinum space effectively and makes the following dissection relatively safe and straightforward. Keywords Pectus excavatum Minimally invasive repair of pectus excavatum Semiflexible thoracoscope Wolkmann bone hook Sternum elevating technique
Introduction Since original report by Nuss et al. [1] in 1998 minimally invasive repair of pectus excavatum (MIRPE) has become worldwide standard procedure for correction of pectus excavatum (PE). Subsequent technical and design modifications have included routine thoracoscopy, the use of an introducer/dissector for creating the substernal tunnel, and routine use of a lateral stabilizer and sutures around the bar and underlying rib to prevent bar displacement [2, 3]. Cardiac injury is the most feared complication of the method [4]. The true incidence of this complication is unknown and probably more frequent than generally believed. About 10 cases of cardiac perforation are reported in literature [4–9]. Two of them were fatal. Bouchard
123
114
Fig. 1 Semiflexible fiberoptic thoracoscope provides optimal visualization from various angles via one site of insertion with low interference of introducer
Pediatr Surg Int (2014) 30:113–117
Fig. 2 An assistant standing at the patient’s left side inserts percutaneously Wolkmann bone hook to the distal sternum and holds the hook up and creates sufficient space between the sternum and heart. The hook opens the anterior mediastinum space effectively and makes the following dissection relatively safe and straightforward
et al. published the most comprehensive paper which presents four severe cardiac injuries that occurred in patients who underwent MIRPE. These complications occurred in different clinical settings, namely in a placement of introducer, in bar removal in patients who had surgery previously. One of these patients died [4]. To prevent this complication, we developed a new simple sternum elevating technique that reduces the risks of cardiac and pericardial injury. The report presents two novel technical innovations of MIRPE which reduce the risk of cardiac injury and review of the corresponding literature.
Materials and methods The operation was performed under general anesthesia with selective pulmonary ventilation using double lumen tracheal tube (Silbroncho, Fuji Systems Corporation, Japan). The MIRPE procedure starts with bilateral transverse thoracic incisions, which are positioned posterior to the anterior axillary line. A subcutaneous tunnel is created from each incision to the pectus ridge. A semiflexible thoracoscope (F-160, Olympus Medical Systems, Tokyo, Japan) is inserted into the pleural cavity through the third small incision on the right side (Fig. 1). An assistant standing at the patient’s left side inserts Wolkmann bone hook (Fig. 2) to the distal sternum percutaneously, and holds the hook up thus creating sufficient space between the sternum and heart. In thoracoscopic view, the sternum is seen to be well elevated and away from the heart (Fig. 3a without the sternum lift; Fig. 3b with sternum lift). The enlarged retrosternal space enables safer passage of thoracoscopically guided introducer. The introducer is passed
123
Fig. 3 In thoracoscopic view, the sternum is seen to be well elevated and away from the heart (a without the sternum lift, b with sternum lift)
through the already widened mediastinum space toward left thoracic cavity. Following this process, the procedure continues as described previously. The concave deformity of the pectus excavatum is corrected after a 180 rotation of the bar and fixation of stabilizer (the introducer, bar,
Pediatr Surg Int (2014) 30:113–117 Table 1 Modification of MIRPE reducing the risk of cardiac injury reported in the literature
115
Author
Extra device
Extra incision
Thoracoscopy
Patients
Tedde et al. [16]
29 Langenbeck
No
Right
25
Takagi et al. [10]
Sternal elevator
No
Right
61
Ohno et al. [15]
No
No
Bilateral
35
Yoon et al. [17]
Kent retractor
Puncture
Right
44
Johnson et al. [18]
Sternal lift
Yes
Right
–
Haecker et al. [20]
Vacuum bell
No
Right
55
Hendrickson et al. [12]
Endo-kittner
No
Left
51
St Peter et al. [19]
No
Yes
No
307
Zallen et al. [13]
70 scope
No
Bilateral
stabilizer are products of Lorenz Surgical Inc, Jacksonville, FL, USA).
Results During the period 2005–2012, the MIRPE was performed in 29 girls and 151 boys; the mean age at the time of surgery was 15.9 years (range 13–18.7 years). The mean Haller index was 4.7 (range 2.7–20.5). The most common complication was pneumothorax (3.3 %) and the less common problems included atelectasis (1.1 %), fluidothorax (0.6 %), and lung injury (0.6 %). Wound complications were abscess (3.3 %), dehiscence (0.6 %), and seroma (0.6 %). The incidence of bar displacement was 2 %. The most serious complication was cardiac perforation when inserting Lorenz introducer. This occurred in a 16-year-old girl; she required urgent sternotomy with right atrial repair and recovered well. External elevation of sternum with a hook was used since this case. Subsequent 113 patients underwent surgery without any serious complications.
Discussion The MIRPE procedure is distinctly superior to traditional open procedure because of minimal surgical trauma without costal cartilage resection. However, since the introducer passes through the limited space between the heart and depressed sternum, the technique carries a risk of lifethreatening complications [10]. Generally, there are three methods to reduce the risk of cardiac injury during MIRPE: thoracoscopy, sternum elevating technique and additional incision (Table 1). Our presented innovation uses semiflexible thoracoscope and hook elevation of the sternum (Figs. 1, 2, 3). Semiflexible fiberoptic thoracoscope provides optimal visualization with low interference of introducer. Wolkmann bone hook (Fig. 2) lifts up the sternum and enlarges the retrosternal space for safer passage of the introducer.
52
Percutaneous insertion of the hook without additional incision, without any extended dissection or trauma to intercostals muscles and mediastinal tissue is easy and reproducible. Corticalis of the sternal bone is strong enough to hold the Wolkmann hook when elevating the anterior chest wall. The clear visualization with semiflexible thoracoscope and elevated sternum with hook are not only safer but also time-saving procedures. Thoracoscopy is an elementary method to prevent cardiac or pulmonary injury. The passage of the introducer into the anterior mediastinum is monitored. However, the field of vision of this procedure could be limited, especially at the point where the deeply depressed sternum and right atrium remain in close contact. To clearly visualize the pericardium and heart, various procedures are used: rightsided thoracoscopy [11], left-sided thoracoscopy [12], bilateral thoracoscopy [13–15] and upper position of thoracoscope. However, the cases of cardiac perforation have occurred despite their use. Right-sided thoracoscopy with scopes with an angle of vision of 30° is most widely used at centers worldwide. Saxena et al. [11] recommended the scopes with an angle of vision of 30° and they speculated that investing in scopes of different sizes such as 45° and 70° does not offer any added advantages to the procedure if the port site is properly selected. Conversely, Zallen et al. [13] have found that the angled scope allows optimal visualization of the mediastinum and the rib cage. They recommend using a 28-cm-long, 70°, 5-mm scope which works better for placing the bar and the wires to secure the bar. Palmer et al. [14] advocated bilateral thoracoscopic repair of pectus excavatum with left-to-right mediastinal dissection which is a safe alternative to the traditional approach, as it allows a more complete visualization of the mediastinum and eliminates the need for additional safety measures such as subxiphoid dissection and elevation. We recommend using semiflexible fiberoptic thoracoscope (F-160, Olympus Medical Systems, Tokyo, Japan) having a solid body and a flexible terminal section (Fig. 1), which provide optimal visualization from various angles
123
116
via one site of insertion. The advantage of flexible thoracoscope is particularly in case of deep deformity, in case of marked displacement of the hearth, in case of high position of diaphragm and in case of interference of introducer. In addition to thoracoscopy, some techniques of mediastinal dissection have been designed to reduce the risk of cardiac injury (Table 1). Hendrickson et al. [12] described modification to the Nuss procedure using the left hemithorax for thoracoscopy rather than the right. The heart is usually the first structure identified and can be kept in the operative field at all times. The second 5-mm port is placed in the inferior aspect of the left vertical incision to accommodate an Endo-kittner, which allows accurate and detailed dissection of the retrosternal area. Once the mediastinal dissection is complete, the Nuss bar introducer is inserted and advanced across the mediastinum under direct visualization. Left thoracoscopy ensures that the heart is under direct visualization during the entire procedure, and the use of the Endo-kittner dissector permits accurate and detailed mediastinal dissection. Authors postulate that other methods to ensure safe substernal dissection such as using a subxiphoid incision are unnecessary. Ohno et al. [15] inserted the introducer into the pleura between the sternum and thymus instead of the thoracic depression. After the introducer reaches the internal cranial position of the left nipple, the thoracoscope is shifted to left and the introducer is subsequently guided down to the corresponding intercostal space. The authors emphasize that their modification allows continual observation of the tip of introducer and thus reduces the risk of fatal injury during insertion across the deep depression. On the other hand, their procedure required more extensive dissection in anterior mediastinum and bilateral thoracoscopy, both of which can increase the incidence of minor complications. Other authors added various sternum elevating techniques, lifting the sternum with elevator, retractor, lift, vacuum bell with or without additional subxiphoid incision to the above-mentioned procedures (Table 1). Tedde et al. described technical modification of the Nuss procedure on a series of 25 patients. They positioned two Langenbeck retractors inside both hemithoraces and pulled them upwards. They speculated that the retractors pull the chest wall up while the heart is moved down by its weight creating more space between the sternum and the pericardial sac [16]. The retractors are inserted via the same incision and via the same subcutaneous channel that is created for introducer. Nevertheless, insertion of retractors causes a larger laceration of intercostal muscles and thus brings some more risk for stability of the bar and overgrowth of local tissue.
123
Pediatr Surg Int (2014) 30:113–117
Takagi et al. [10] reported innovation with a newly design sternum elevator, that is now commercially available. No extra skin incision is needed, the elevator is inserted from the right, in the same point as introducer. The elevator has the same curvature as a Nuss introducer and the same site of insertion but the author postulates that the interference is minimal. Yoon et al. [17] used the so-called Crane technique for sternal elevation in adolescent and adult. The wire is sutured onto the sternum and the sternum is elevated by pulling the wire up with the Kent retractor. They stress that this technique minimizes mediastinal injury during passing and rotating the bar by increasing the anterior mediastinal space. Johnson et al. [18] developed a novel sternal lift system and they believed that it will help eliminate intraoperative cardiac perforation in the Nuss procedure. They also speculate that this technique will reduce the duration of the operation and other more common complications, and it is feasible even in patients with severe pectus excavatum with Haller index above 7. Positioning of elevator requires additional subxiphoid incision which is the weakness of this method. St Peter et al. [19] have used a subxiphoid incision to allow finger guidance to protect the mediastinum which obviates the need for thoracoscopy or any other elevating device. The subxiphoid-guided technique is a simple, safe, and reproducible method for the MIRPE that obviates the need for thoracoscopy. The subxiphoid incision, however, adds an additional scar to the anterior chest wall that is sometimes cosmetically unacceptable to the indications for PE repair that is often predominantly cosmetic. Haecker et al. evaluated the routine use of the vacuum bell for elevating the sternum during MIRPE in 50 patients. The use of the vacuum bell led to a clear elevation of the sternum as confirmed by thoracoscopy. Advancement of the pectus introducer and placement of the pectus bar were safe, successful, and uneventful in all patients. No cardiac and/or pericardial lesion as well as no lesion of the mammary vessels was noted [20].
Conclusion MIRPE procedure is an effective method with elegant cosmetic results. Modifications of the original method help decrease the complication rate. Technical innovation using semiflexible thoracoscope and hook elevation of the sternum reduces the risk of cardiac injury. The hook opens the anterior mediastinum space effectively and makes the following dissection relatively safe and straightforward. Semiflexible fiberoptic thoracoscope provides optimal
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visualization from various angles via one site of insertion with low interference of introducer. Acknowledgments Authors would like to thank Ms Jana Kalousova´ M.D. for expert consultation. Conflict of interest of interest.
The authors declare that they have no conflict
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