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Endovascular treatment of an iatrogenic thoracic aortic injury after spinal instrumentation: case report
Endovascular treatment of an iatrogenic thoracic aortic injury after spinal instrumentation: Case report Michael E. Minor, MD, Nicholas J. Morrissey, MD, Richard Peress, MD, Alfio Carroccio, MD, Sharif Ellozy, MD, Gautam Agarwal, MD, Victoria Teodorescu, MD, Larry H. Hollier, MD, and Michael L. Marin, MD, New York, NY Iatrogenic aortic injuries after spinal surgery have been described, but are rare. We describe a case of a 77-year-old woman who underwent surgical correction of a debilitating spinal deformity at an outside institution. Postoperative thoracic spine radiographs and computed tomography scans revealed a misplaced pedicle screw at T5, which was impinging on the descending thoracic aortic wall. The patient was brought to the operating room, where a thoracic stent graft was deployed under fluoroscopic guidance as the malpositioned screw was manually retracted. The patient had an uneventful postoperative course, and was discharged within 24 hours. This case represents a rare but potentially morbid vascular complication of spinal instrumentation surgery that was successfully treated without the need for thoracotomy. (J Vasc Surg 2004;39:893-6.)
CASE REPORT A 77-year-old woman with a history of debilitating scoliosis underwent surgical correction of spinal deformity with placement of posterior thoracic spinal instrumentation at an outside institution. The instrumentation consisted of two longitudinal rods secured to the spine with a series of posteriorly placed pedicle screws at several vertebral levels (Fig 1). The patient tolerated this procedure well, and the perioperative course was uneventful. However, a routine follow-up non– contrast-enhanced computed tomography (CT) scan obtained before the first postoperative visit revealed a misplaced T5 pedicle screw on the left side. The malpositioned screw had exited the lateral pedicle cortex and was in close proximity to the posteromedial aspect of the thoracic aorta (Fig 2). The patient was transferred to our institution for further evaluation and management. After transfer, contrast-enhanced CT scans and aortograms suggested that the malpositioned pedicle screw had penetrated the thoracic aortic wall (Figs 3, 4). There was no evidence of surrounding hematoma, extravasation of contrast medium, or pleural effusion. The patient remained hemodynamically stable, and 2 days later was taken to the operating room for endoluminal repair. The operating room was prepared for immediate conversion to open thoracotomy in the event that uncontrolled hemorrhage was encountered. After administration of general anesthesia, transesophageal echocardiograms further suggested that the tip of the screw was within the aortic lumen. With the patient in a modified left thoracotomy position, and under direct fluoroscopic guidance, a single 70 ⫻ 36-mm Talent thoracic endoprosthesis was introFrom the Department of Surgery, Division of Vascular Surgery, The Mount Sinai School of Medicine. Competition of interest: none. Reprint requests: Michael L. Marin, MD, The Mount Sinai School of Medicine, 5 East 98th St, Box 1273, New York, NY 10029 (e-mail: [email protected]). 0741-5214/$30.00 Copyright © 2004 by The Society for Vascular Surgery. doi:10.1016/j.jvs.2003.10.056
duced through the left common femoral artery into the proximal descending thoracic aorta in the region of the injury. This investigational device was made available as part of an investigatorsponsored clinical trial. Before deployment the device was positioned with half of its length above and below the site of the aortic puncture. Simultaneously an orthopedic surgery team member exposed the screw through a posterior incision, and at the precise time of device deployment the screw was manually retracted and removed (Fig 5, A, B). This close coordination between vascular and orthopedic surgeons was essential to obtain an immediate seal and to prevent perforation of the graft by the screw tip. Total operative time was 100 minutes, and intraoperative blood loss was minimal. There was no evidence of a leak on the completion aortogram. The patient remained neurologically intact, and was discharged within 24 hours. A follow-up contrast-enhanced CT scan was obtained 1 month after the repair (Fig 6).
DISCUSSION Iatrogenic vascular injuries during spinal surgery are rare, but have been described.1 Most cases have been associated with lumbar discectomy, but major vascular complications associated with spinal stabilization procedures have been reported as well.1-12 The close anatomic relationship of the spine to the aorta places it and other major retroperitoneal structures at risk during these complex procedures. Anatomic studies have shown that, even in severe scoliosis, the aorta persistently follows and adheres to the abnormal curves of the spine.13 Moreover, reports that have examined the accuracy of pedicle screw placement have shown that a large percentage of screws penetrate the pedicle cortex, placing major vascular structures at risk for iatrogenic injury.14 Most vascular injuries associated with spinal surgery are delayed, occurring after chronic irritation of the pulsating aortic wall against a metallic implant.2,3,7 However, the potential for immediate major vascular complications dur893
894 Minor et al
JOURNAL OF VASCULAR SURGERY April 2004
Fig 3. A and B, CT angiograms and of the thoracic aorta suggest that the T5 pedicle screw may penetrate the thoracic aorta. Fig 1. Lateral chest radiograph demonstrates posterior spinal instrumentation.
Fig 2. Non– contrast-enhanced CT scan obtained 1 month after spinal instrumentation. The T5 pedical screw is seen impinging on the thoracic aorta (TA).
ing the placement of spinal instrumentation exists, and a few cases have been reported.4,6,8 Matsuzaki et al8 reported a thoracic aortic perforation from an anteriorly placed pedicle screw. In that case, much like ours, the aortic injury was not immediately evident intraoperatively, but was rec-
ognized only on follow-up CT scans. The injury had been sealed by the pedicle screw, which prevented hemorrhage. Repair, however, required extensive surgery including thoracotomy, cardiopulmonary bypass, and replacement of an 8-cm segment of proximal descending thoracic aorta. The patient recovered without any major systemic complications.8 We present a similar case of thoracic aortic injury after errant placement of a posterior pedicle screw. As in the above case, there were no immediate clinical manifestations of aortic perforation, and the injury was recognized only at routine postoperative imaging. Although contrastenhanced CT scans and aortograms confirmed indentation of the aortic wall by the tip of the malpositioned pedicle screw, it could not be definitively determined whether the tip of the screw was intraluminal or simply abutting the aortic wall. In either case, given the significant risk for delayed aortic perforation or pseudoaneurysm formation from chronic irritation of the pulsating aorta against this sharp, metallic foreign body, intervention was indicated to prevent these potentially serious, future complications. Although aortic injuries from misplaced pedicle screws have been described, we are not aware of another report in the literature of aortic stent grafting used to repair such a lesion. Historically, the only available therapy would have been open thoracotomy and direct surgical repair of the perforated aorta. This approach may be associated with a
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Fig 4. Thoracic aortogram demonstrates the misplaced pedicle screw.
morbidity rate as high as 50%, with the major complications including spinal cord ischemia and pulmonary failure.15,16 Since the first description by Dake et al10 of the use of endovascular grafts to treat thoracic aortic aneurysms, this technique has been applied to traumatic lesions as well.17-21 The major advantages of the endoluminal approach include minimal invasiveness and lower associated morbidity. Postoperative pulmonary failure and paraplegia rates are considerably lower, because thoracotomy and prolonged proximal aortic crossclamping are avoided.22 In addition, the extent of aortic coverage is often shorter than with open repair, and most procedures can be performed without the need for general anesthesia. Despite the clear short-term advantages of endovascular stent grafting in the thoracic aorta, the long-term durability of this approach has been questioned. One reason for this is the potential for endoleak, which occurs in more than 20% of patients.23 As with abdominal aortic aneurysms, type I, attachment site leaks carry the poorest prognosis, because they are associated with systemic pressurization of the aneurysm sac. Important requirements to achieve adequate proximal and distal “seal” are adequate coverage of the diseased aortic segment and landing zones free from thrombus, which might prohibit adequate stent-graft fixation. Moreover, some have suggested that aneurysm remodeling after successful stent grafting can lead to graft migration and subsequent endoleak.24 These considerations are of particular significance in the treatment of aneurysm disease in which extensive aortic calcification and
Fig 5. Intraoperative aortograms before (A) and immediately after (B) stent-graft deployment. Note that one of the two superiormost screws (arrow) has been removed.
Fig 6. CT angiogram obtained 1 month after stent-graft placement. Section shown is at the level of injury.
intraluminal thrombus are expected. However, in our case, with a focal aortic perforation in an otherwise normal vessel, adequate graft fixation above and below the perforation site was facilitated and morphologic changes leading to graft migration are less likely.
896 Minor et al
CONCLUSION This case illustrates a rare, but potentially morbid, vascular complication of spinal instrumentation surgery. In the hemodynamically stable patient, endoluminal repair provides a less invasive and potentially less morbid alternative to open surgery. Although the long-term durability of endovascular stent grafting in the thoracic aorta is unclear, the focal nature of this lesion, in the setting of an otherwise normal aorta, provides an ideal application for this technique. REFERENCES 1. Anda S, Aakhus S, Skaanes KO, Sande E, Schrader H. Anterior perforations in lumbar discectomies: a report of four cases of vascular complications and a CT study of the prevertebral lumbar anatomy. Spine 1991;16:54-60. 2. Woolsey RM. Aortic laceration after anterior spinal fusion. Surg Neurol 1986;25:267-8. 3. Ohnishi T, Neo M, Matsushita M, Komeda M, Koyama T, Nakamura T. Delayed aortic rupture caused by an implanted anterior spinal device. J Neurosurg 2001;95:253-6. 4. Smythe WR, Carpenter JP. Upper abdominal aortic injury during spinal surgery. J Vasc Surg 1997;25:774-7. 5. Hernigou P, Germany W. Evaluation of the risk of mediastinal or retroperitoneal injuries caused by dorso-lumbar pedicle screws. Rev Chir Orthop 1998;84:411-20. 6. Vanichkachorn JS, Vaccaro AR, Cohen MJ, Cotler JM. Potential large vessel injury during thoracolumbar pedicle screw removal: a case report. Spine 1997;22:110-3. 7. Jendrisak MD. Spontaneous abdominal aortic rupture from erosion by a lumbar spine fixation device: a case report. Surgery 1986;99:631-3. 8. Matsuzaki H, Tokuhashi Y, Wakabayashi K, Kitamura S. Penetration of a screw into the thoracic aorta in anterior spinal instrumentation: a case report. Spine 1993;18:2327-31. 9. Bialy T, Gooch AS, Shahriari A. High-output congestive failure due to arteriovenous fistula resulting from lumbar disc surgery. Angiology 1988;39:616-9. 10. Birkeland IW Jr, Taylor TF. Major vascular injuries in lumbar disc surgery. J Bone Joint Surg [Br] 1969;51:4-19.
JOURNAL OF VASCULAR SURGERY April 2004
11. Brewster DC, May AL, Darling RC, Abbott WM, Moncure AC. Variable manifestations of vascular injury during lumbar disc surgery. Arch Surg 1979;114:1026-30. 12. Salander JM, Youkey JR, Rich NM, Olson DW, Clagett GP. Vascular injury related to lumbar disc surgery. J Trauma 1984;24:628-31. 13. Nathan H. Relations of the soft structures of the posterior mediastinum in the scoliotic spine. Acta Anat (Basel) 1988;133:260-4. 14. Vaccaro AR, Rizzolo SJ, Balderston RA, Allardyce TJ, Garfin SR, Dolinskas C. Placement of pedicle screws in the thoracic spine. II: An anatomical and radiographic assessment. J Bone Joint Surg [Am] 1995; 77:1200-6. 15. Finkelmeier BA, Mentzer RM, Kaiser DL, et al. Chronic traumatic thoracic aneurysm. J Cardiovasc Surg 1982;84:257-66. 16. Bacharach JM, Garrat KN, Rooke TW. Chronic traumatic thoracic aneurysm: report of two cases with the question of timing for surgical intervention. J Vasc Surg 1993;17:780-3. 17. Dake MD, Miller DC, Semba CP, et al. Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms. N Engl J Med 1994;331:1729-34. 18. Kato N, Dake MD, Miller DC, et al. Traumatic thoracic aortic aneurysm: treatment with endovascular stent-grafts. Radiology 1997;205: 657-62. 19. Semba CP, Katon N, Kee ST. Acute rupture of the descending thoracic aorta: repair with the use of endovascular stent-grafts. J Vasc Interv Radiol 1997;8:337-42. 20. Desgranges P, Mialhe C, Cavillon A. Endovascular repair of posttraumatic thoracic pseudoaneurysm with a stent-graft. AJR Am J Roentgenol 1997;169:1743-5. 21. Deshpande A, Mossop P, Gurry J, et al. Treatment of traumatic false aneurysm of the thoracic aorta with endoluminal grafts. J Endovasc Surg 1998;5:120-5. 22. Mitchell RS, Miller DC, Dake MD, et al. Thoracic aortic aneurysm repair with an endovascular stent-graft: the “first generation.” Ann Thorac Surg 1999;67:1971-80. 23. Orend KH, Scharrer-Pamler R, Kapfer X, Kotsis T, Gorich J, Sunder Plassmann L. Endovascular treatment in diseases of the descending thoracic aorta: 6-year results of a single center. J Vasc Surg 2003;37:91-9. 24. Resch T, Koul B, Dias NV, Lindblad B, Ivancev K. Changes in aneurysm morphology and stent-graft configuration after endovascular repair of aneurysms of the descending thoracic aorta. J Thorac Cardiovasc Surg 2001;122:47-52. Submitted Jul 3, 2003; accepted Oct 17, 2003. Available online Feb 6, 2004.
CASE REPORT A 77-year-old woman with a history of debilitating scoliosis underwent surgical correction of spinal deformity with placement of posterior thoracic spinal instrumentation at an outside institution. The instrumentation consisted of two longitudinal rods secured to the spine with a series of posteriorly placed pedicle screws at several vertebral levels (Fig 1). The patient tolerated this procedure well, and the perioperative course was uneventful. However, a routine follow-up non– contrast-enhanced computed tomography (CT) scan obtained before the first postoperative visit revealed a misplaced T5 pedicle screw on the left side. The malpositioned screw had exited the lateral pedicle cortex and was in close proximity to the posteromedial aspect of the thoracic aorta (Fig 2). The patient was transferred to our institution for further evaluation and management. After transfer, contrast-enhanced CT scans and aortograms suggested that the malpositioned pedicle screw had penetrated the thoracic aortic wall (Figs 3, 4). There was no evidence of surrounding hematoma, extravasation of contrast medium, or pleural effusion. The patient remained hemodynamically stable, and 2 days later was taken to the operating room for endoluminal repair. The operating room was prepared for immediate conversion to open thoracotomy in the event that uncontrolled hemorrhage was encountered. After administration of general anesthesia, transesophageal echocardiograms further suggested that the tip of the screw was within the aortic lumen. With the patient in a modified left thoracotomy position, and under direct fluoroscopic guidance, a single 70 ⫻ 36-mm Talent thoracic endoprosthesis was introFrom the Department of Surgery, Division of Vascular Surgery, The Mount Sinai School of Medicine. Competition of interest: none. Reprint requests: Michael L. Marin, MD, The Mount Sinai School of Medicine, 5 East 98th St, Box 1273, New York, NY 10029 (e-mail: [email protected]). 0741-5214/$30.00 Copyright © 2004 by The Society for Vascular Surgery. doi:10.1016/j.jvs.2003.10.056
duced through the left common femoral artery into the proximal descending thoracic aorta in the region of the injury. This investigational device was made available as part of an investigatorsponsored clinical trial. Before deployment the device was positioned with half of its length above and below the site of the aortic puncture. Simultaneously an orthopedic surgery team member exposed the screw through a posterior incision, and at the precise time of device deployment the screw was manually retracted and removed (Fig 5, A, B). This close coordination between vascular and orthopedic surgeons was essential to obtain an immediate seal and to prevent perforation of the graft by the screw tip. Total operative time was 100 minutes, and intraoperative blood loss was minimal. There was no evidence of a leak on the completion aortogram. The patient remained neurologically intact, and was discharged within 24 hours. A follow-up contrast-enhanced CT scan was obtained 1 month after the repair (Fig 6).
DISCUSSION Iatrogenic vascular injuries during spinal surgery are rare, but have been described.1 Most cases have been associated with lumbar discectomy, but major vascular complications associated with spinal stabilization procedures have been reported as well.1-12 The close anatomic relationship of the spine to the aorta places it and other major retroperitoneal structures at risk during these complex procedures. Anatomic studies have shown that, even in severe scoliosis, the aorta persistently follows and adheres to the abnormal curves of the spine.13 Moreover, reports that have examined the accuracy of pedicle screw placement have shown that a large percentage of screws penetrate the pedicle cortex, placing major vascular structures at risk for iatrogenic injury.14 Most vascular injuries associated with spinal surgery are delayed, occurring after chronic irritation of the pulsating aortic wall against a metallic implant.2,3,7 However, the potential for immediate major vascular complications dur893
894 Minor et al
JOURNAL OF VASCULAR SURGERY April 2004
Fig 3. A and B, CT angiograms and of the thoracic aorta suggest that the T5 pedicle screw may penetrate the thoracic aorta. Fig 1. Lateral chest radiograph demonstrates posterior spinal instrumentation.
Fig 2. Non– contrast-enhanced CT scan obtained 1 month after spinal instrumentation. The T5 pedical screw is seen impinging on the thoracic aorta (TA).
ing the placement of spinal instrumentation exists, and a few cases have been reported.4,6,8 Matsuzaki et al8 reported a thoracic aortic perforation from an anteriorly placed pedicle screw. In that case, much like ours, the aortic injury was not immediately evident intraoperatively, but was rec-
ognized only on follow-up CT scans. The injury had been sealed by the pedicle screw, which prevented hemorrhage. Repair, however, required extensive surgery including thoracotomy, cardiopulmonary bypass, and replacement of an 8-cm segment of proximal descending thoracic aorta. The patient recovered without any major systemic complications.8 We present a similar case of thoracic aortic injury after errant placement of a posterior pedicle screw. As in the above case, there were no immediate clinical manifestations of aortic perforation, and the injury was recognized only at routine postoperative imaging. Although contrastenhanced CT scans and aortograms confirmed indentation of the aortic wall by the tip of the malpositioned pedicle screw, it could not be definitively determined whether the tip of the screw was intraluminal or simply abutting the aortic wall. In either case, given the significant risk for delayed aortic perforation or pseudoaneurysm formation from chronic irritation of the pulsating aorta against this sharp, metallic foreign body, intervention was indicated to prevent these potentially serious, future complications. Although aortic injuries from misplaced pedicle screws have been described, we are not aware of another report in the literature of aortic stent grafting used to repair such a lesion. Historically, the only available therapy would have been open thoracotomy and direct surgical repair of the perforated aorta. This approach may be associated with a
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Fig 4. Thoracic aortogram demonstrates the misplaced pedicle screw.
morbidity rate as high as 50%, with the major complications including spinal cord ischemia and pulmonary failure.15,16 Since the first description by Dake et al10 of the use of endovascular grafts to treat thoracic aortic aneurysms, this technique has been applied to traumatic lesions as well.17-21 The major advantages of the endoluminal approach include minimal invasiveness and lower associated morbidity. Postoperative pulmonary failure and paraplegia rates are considerably lower, because thoracotomy and prolonged proximal aortic crossclamping are avoided.22 In addition, the extent of aortic coverage is often shorter than with open repair, and most procedures can be performed without the need for general anesthesia. Despite the clear short-term advantages of endovascular stent grafting in the thoracic aorta, the long-term durability of this approach has been questioned. One reason for this is the potential for endoleak, which occurs in more than 20% of patients.23 As with abdominal aortic aneurysms, type I, attachment site leaks carry the poorest prognosis, because they are associated with systemic pressurization of the aneurysm sac. Important requirements to achieve adequate proximal and distal “seal” are adequate coverage of the diseased aortic segment and landing zones free from thrombus, which might prohibit adequate stent-graft fixation. Moreover, some have suggested that aneurysm remodeling after successful stent grafting can lead to graft migration and subsequent endoleak.24 These considerations are of particular significance in the treatment of aneurysm disease in which extensive aortic calcification and
Fig 5. Intraoperative aortograms before (A) and immediately after (B) stent-graft deployment. Note that one of the two superiormost screws (arrow) has been removed.
Fig 6. CT angiogram obtained 1 month after stent-graft placement. Section shown is at the level of injury.
intraluminal thrombus are expected. However, in our case, with a focal aortic perforation in an otherwise normal vessel, adequate graft fixation above and below the perforation site was facilitated and morphologic changes leading to graft migration are less likely.
896 Minor et al
CONCLUSION This case illustrates a rare, but potentially morbid, vascular complication of spinal instrumentation surgery. In the hemodynamically stable patient, endoluminal repair provides a less invasive and potentially less morbid alternative to open surgery. Although the long-term durability of endovascular stent grafting in the thoracic aorta is unclear, the focal nature of this lesion, in the setting of an otherwise normal aorta, provides an ideal application for this technique. REFERENCES 1. Anda S, Aakhus S, Skaanes KO, Sande E, Schrader H. Anterior perforations in lumbar discectomies: a report of four cases of vascular complications and a CT study of the prevertebral lumbar anatomy. Spine 1991;16:54-60. 2. Woolsey RM. Aortic laceration after anterior spinal fusion. Surg Neurol 1986;25:267-8. 3. Ohnishi T, Neo M, Matsushita M, Komeda M, Koyama T, Nakamura T. Delayed aortic rupture caused by an implanted anterior spinal device. J Neurosurg 2001;95:253-6. 4. Smythe WR, Carpenter JP. Upper abdominal aortic injury during spinal surgery. J Vasc Surg 1997;25:774-7. 5. Hernigou P, Germany W. Evaluation of the risk of mediastinal or retroperitoneal injuries caused by dorso-lumbar pedicle screws. Rev Chir Orthop 1998;84:411-20. 6. Vanichkachorn JS, Vaccaro AR, Cohen MJ, Cotler JM. Potential large vessel injury during thoracolumbar pedicle screw removal: a case report. Spine 1997;22:110-3. 7. Jendrisak MD. Spontaneous abdominal aortic rupture from erosion by a lumbar spine fixation device: a case report. Surgery 1986;99:631-3. 8. Matsuzaki H, Tokuhashi Y, Wakabayashi K, Kitamura S. Penetration of a screw into the thoracic aorta in anterior spinal instrumentation: a case report. Spine 1993;18:2327-31. 9. Bialy T, Gooch AS, Shahriari A. High-output congestive failure due to arteriovenous fistula resulting from lumbar disc surgery. Angiology 1988;39:616-9. 10. Birkeland IW Jr, Taylor TF. Major vascular injuries in lumbar disc surgery. J Bone Joint Surg [Br] 1969;51:4-19.
JOURNAL OF VASCULAR SURGERY April 2004
11. Brewster DC, May AL, Darling RC, Abbott WM, Moncure AC. Variable manifestations of vascular injury during lumbar disc surgery. Arch Surg 1979;114:1026-30. 12. Salander JM, Youkey JR, Rich NM, Olson DW, Clagett GP. Vascular injury related to lumbar disc surgery. J Trauma 1984;24:628-31. 13. Nathan H. Relations of the soft structures of the posterior mediastinum in the scoliotic spine. Acta Anat (Basel) 1988;133:260-4. 14. Vaccaro AR, Rizzolo SJ, Balderston RA, Allardyce TJ, Garfin SR, Dolinskas C. Placement of pedicle screws in the thoracic spine. II: An anatomical and radiographic assessment. J Bone Joint Surg [Am] 1995; 77:1200-6. 15. Finkelmeier BA, Mentzer RM, Kaiser DL, et al. Chronic traumatic thoracic aneurysm. J Cardiovasc Surg 1982;84:257-66. 16. Bacharach JM, Garrat KN, Rooke TW. Chronic traumatic thoracic aneurysm: report of two cases with the question of timing for surgical intervention. J Vasc Surg 1993;17:780-3. 17. Dake MD, Miller DC, Semba CP, et al. Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms. N Engl J Med 1994;331:1729-34. 18. Kato N, Dake MD, Miller DC, et al. Traumatic thoracic aortic aneurysm: treatment with endovascular stent-grafts. Radiology 1997;205: 657-62. 19. Semba CP, Katon N, Kee ST. Acute rupture of the descending thoracic aorta: repair with the use of endovascular stent-grafts. J Vasc Interv Radiol 1997;8:337-42. 20. Desgranges P, Mialhe C, Cavillon A. Endovascular repair of posttraumatic thoracic pseudoaneurysm with a stent-graft. AJR Am J Roentgenol 1997;169:1743-5. 21. Deshpande A, Mossop P, Gurry J, et al. Treatment of traumatic false aneurysm of the thoracic aorta with endoluminal grafts. J Endovasc Surg 1998;5:120-5. 22. Mitchell RS, Miller DC, Dake MD, et al. Thoracic aortic aneurysm repair with an endovascular stent-graft: the “first generation.” Ann Thorac Surg 1999;67:1971-80. 23. Orend KH, Scharrer-Pamler R, Kapfer X, Kotsis T, Gorich J, Sunder Plassmann L. Endovascular treatment in diseases of the descending thoracic aorta: 6-year results of a single center. J Vasc Surg 2003;37:91-9. 24. Resch T, Koul B, Dias NV, Lindblad B, Ivancev K. Changes in aneurysm morphology and stent-graft configuration after endovascular repair of aneurysms of the descending thoracic aorta. J Thorac Cardiovasc Surg 2001;122:47-52. Submitted Jul 3, 2003; accepted Oct 17, 2003. Available online Feb 6, 2004.