Thoracic endovascular aortic repair for traumatic aortic transection
Article Outline
Background
Traumatic transection of the thoracic aorta is a highly morbid injury. Treatment may be delayed while attention focuses on concomitant injuries. Thoracic endovascular aortic repair (TEVAR) is effective but remains controversial in these often-young patients. We reviewed our experience in acute and subacute treatment of these injuries with TEVAR.
Methods
A retrospective analysis of five men and five women who underwent TEVAR for aortic transection from 1999 to 2007 was conducted. Procedures were performed with standard endovascular techniques. Follow-up included computed tomography at 1 month and yearly thereafter.
Results
Mean age was 44 years (range, 20 to 84 years). Motor vehicle accidents accounted for 7 injuries, a snowmobile accident for 1, skydiving for 1, and balloon angioplasty of a coarctation for 1. Average diameter of the proximal landing zone was 25 mm (range, 23 to 29 mm). Mean external iliac size was 10 mm (range, 7 to 15 mm), and no conduits were required. Immediate technical success was 90%, with no 30-day mortality. Seven patients underwent repair acutely (≤24 hours) and three patients subacutely (range, 4 days to 2 months) for pseudoaneurysm. Four patients had procedures for concomitant injuries before their transection was repaired (3 laparotomies and a fixation for open fracture). One endoleak was noted, which resolved by the 1-month follow-up. The lone device-related complication was an endograft collapse at 5 months managed by repeat endografting, which was complicated by aortoesophageal fistula requiring esophagectomy and open reconstruction. No iliac injuries occurred. At 20-months of mean follow-up (range, 2 to 70 months), all patients are alive and well.
Conclusions
TEVAR for traumatic aortic transection is feasible, with good initial success. Repair can be delayed in selected cases. Continued surveillance is necessary to ensure good long-term outcomes in these young patients. Care must be taken when performing TEVAR for this off-label indication because these devices are designed for the larger aortic diameters of aneurysm patients.
Traumatic thoracic aortic transection (TAT) carries an overall mortality of >90%.1 More than 80% of patients with this injury die at the scene of the accident, and of those who do reach a hospital, a 1% mortality per hour has been described.1 Delay in treatment for this injury is sometimes necessary while diagnostic and management efforts focus on other injuries. In some cases, initially unrecognized transections can progress to chronic contained perforations with ongoing risk of rupture.
The main mechanism of injury in TAT is movement of the mobile aortic arch against the fixed proximal descending thoracic aorta during deceleration injury, such as in a motor vehicle accident or a fall.2 In fact, 15% of all deaths from motor vehicle accidents are thought to result from aortic injury, second only to the 60% caused by head injury.3
For nearly 50 years, open repair of TAT has been the standard of care for this injury.4 Unfortunately, this treatment can be lengthy, requires a thoracotomy with aortic cross-clamping, and incurs its own significant risks, which often can be prohibitive in patients with associated head, abdominal, and orthopedic injuries. Operative mortality can be as high as 28%, and paraplegia affects up to 14% of patients after surgery.5
Repair of these injuries with thoracic aortic stent grafts promises to offer a lower risk alternative to open surgery for these patients. Several case reports and small series of patients with TAT treated in the acute setting with stent grafts have described acceptable technical success, complication, and mortality rates.6, 7, 8, 9, 10 In theory, the avoidance of a thoracotomy and aortic cross-clamping should decrease complication and death rates after aortic repair in these complex, critically ill patients.
This study reports our experience in the endovascular repair of TAT performed in the acute setting as well as the subacute repair of contained pseudoaneurysms after treatment of other injuries.
Patients and methods
A retrospective review was conducted of all patients who underwent endovascular repair of TAT performed by the Division of Vascular Surgery at the University of Pittsburgh Medical Center between December 1999 and January 2007. Institutional Review Board approval for this study was obtained. Study variables analyzed included age, sex, mechanism of injury, associated injuries, time elapsed between injury and stent grafting, type and size of stent graft, stent graft–associated complications, and mortality. All radiographic imaging was reviewed to identify the method of diagnosis, to obtain morphologic information about the aortic transection, and to measure aortic and external iliac artery diameters.
In acute settings, standard advanced trauma life support protocols were used to assess patients, and life-threatening injuries such as intraperitoneal hemorrhage were addressed first. Then the transection repair was performed by using a Cook Zenith TX2 TAA Endovascular Graft (Cook Inc, Bloomington, Ind) or a Gore TAG Thoracic Endoprosthesis (W. L. Gore & Associates Inc, Flagstaff, Ariz) as described previously.11 Gore Excluder extension cuffs were used to repair the transection in one patient. No treatment delay occurred because of device unavailability in our institution. All patients were systemically heparinized with 80 U/kg and then reversed at the completion of the procedure. Prophylactic spinal drainage was not performed.
Patients underwent computed tomography (CT) angiography of the chest and four-view plain chest radiography before discharge from the hospital, at 1 month, and then yearly with an office visit. Follow-up information for these patients was obtained from clinic records, and CT scans were reviewed to assess for complications such as endoleak, migration, or collapse.
Results
Ten patients (5 men and 5 women) underwent thoracic endovascular aortic repair (TEVAR) for TAT during the study period. Mean age was 44 years (range, 20 to 84 years). Motor vehicle accidents accounted for seven transections, a snowmobile accident accounted for one, a skydiving injury accounted for another, and an iatrogenic injury during balloon angioplasty for an aortic coarctation for the last. Other associated injuries are detailed in Table I.
Table I. Associated injuries
| Patient | Associated injury | Procedures before aortic repair | Time to repair |
|---|---|---|---|
| 1 | None | None | Immediate |
| 2 | Diaphragmatic rupture, pneumothorax, rib fractures | None | Immediate |
| 3 | Rib fractures | None | Immediate |
| 4 | Pelvic fracture | None | Immediate |
| 5 | Liver laceration, jejunal perforation, gastric perforation, pelvic fracture | Laparotomy | Immediate |
| 6 | Hemothorax, hemoperitoneum, femur fracture | Laparotomy | 1 d |
| 7 | Diaphragmatic rupture, splenic laceration | Laparotomy | 1d |
| 8 | Liver laceration, pelvic fracture, pulmonary contusion, ileal perforation | None | 4d |
| 9 | Liver/splenic laceration, pelvic fracture, tibia fracture | Reduction and fixation of tibia | 6d |
| 10 | Liver laceration, pelvic fracture, femur fracture | None | 2mon |
Time from injury to treatment varied greatly in this series. Treatment was acute in seven patients, defined here as ≤24 hours of injury. Late transfer from a referring hospital and a false-negative initial CT scan resulted in delayed subacute TEVAR in two patients, at 4 and 6 days after injury, respectively. In another patient with a stable aortic transection and a severe liver laceration with pelvic hemorrhage, TEVAR was delayed by 2 months at the discretion of the referring physician (Table I).
Four patients underwent operations for other acute life-threatening injuries before repair of their aortic transection (Table I). These operations included an exploratory laparotomy in three patients and open reduction and fixation of an open long-bone fracture in one patient.
The diagnosis of TAT was made by CT in all patients. The location of injury was at the expected anatomic location, within 1 to 3 cm of the aortic isthmus, in all patients. A Gore TAG Thoracic Endoprosthesis was used in eight patients and a Cook Zenith TX2 TAA Endovascular Graft in one. Two Gore Excluder extension cuffs were used in the repair of the patient with the iatrogenic TAT. The repair in two patients was in the context of a clinical investigational protocol, and the rest represented off-label usage of these devices.
Average aortic diameter at the isthmus was 25 mm (range, 23 to 29 mm), and stent graft diameters were 26 to 30 mm, with lengths of 3 cm for the extension cuffs to 15 cm for the longer thoracic stent grafts. Mean external iliac diameter of these patients was 10 mm (range, 7 to 15 mm). No conduits were required (Table II).
Table II. Operative variables and complications
| Variable⁎ | Value |
|---|---|
| Gore TAG† | 8 |
| Gore Excluder extension cuffs† | 1 |
| Cook TX2‡ | 1 |
| Mean aortic diameter, mm (range) | 25(23-29) |
| Stent graft diameter range, mm | 26-30 |
| Mean external iliac diameter, mm (range) | 10(7-15) |
| Left subclavian covered | 2 |
| Left arm ischemia | 0 |
| Left subclavian revascularization | 0 |
| Paraplegia | 0(0) |
| Endoleak | 1(10) |
| Collapse | 1(10) |
| Migration | 0(0) |
| Iliac injury or groin complication | 0(0) |
| Procedure related complication | 1(10) |
| Mortality | 0(0) |
| Mean follow up, mon (range) | 20(2-70) |
⁎Data are presented as number (%) unless indicated otherwise. |
†W.L. Gore & Associates, Flagstaff, Ariz. |
‡Cook Inc, Cook Inc, Bloomington, Ind. |
Completion angiography revealed no endoleaks or other graft-related complications; however, one patient did have a small proximal type 1 leak at the lesser curve of the arch on predischarge CT that resolved by the 1-month follow-up. This patient accounts for an immediate technical success rate of 90%. There were no 30-day deaths.
In eight cases, the stent graft was deployed distal to the left subclavian artery origin. The stent graft intentionally covered the left subclavian artery origin in two patients, and no sequelae developed as a result. No patient presented with a spinal cord ischemic injury or stroke. There were no groin complications or iliac artery injuries. At a mean of 20 months of follow-up, all patients are doing well (Table II).
A late graft-related complication occurred in a 50 year-old man whose endograft collapsed 5 months after repair. His aortic transection resulted from a skydiving accident (Fig, A). At the initial repair, he was treated with a 26-mm × 10-cm TAG device because his proximal aortic neck diameter measured 23 mm (Fig, B). The completion angiogram showed a small but appreciable bird’s beak without an endoleak (Fig, C). A CT scan at 3 months revealed that the bird’s beak was still present, with no endoleak or graft collapse. At 5 months from the initial repair, he experienced new onset of chest pain and was diagnosed with a recurrent pseudoaneurysm at the site of the original TAT secondary to endograft collapse (Fig, D). This was managed by a secondary extension graft. Because the transverse arch proximal to the left subclavian artery measured 25 mm in diameter, a 28-mm × 15-cm TAG device was deployed with coverage of the left subclavian artery origin (Fig, E). However, 1 month after the placement of this second stent graft, the patient presented with sepsis related to aortoesophageal fistula. He ultimately underwent esophagectomy, excision of the stent grafts, and open aortic replacement; fortunately, he recovered and now is doing well. This patient accounts for an overall late graft-related complication rate of 10%.
A, A 50-year-old man was found to have a thoracic aortic transection after a skydiving accident (arrow). B, He underwent a successful thoracic endovascular aneurysm repair with a 26-mm × 10-cm TAG endoprosthesis (W. L Gore and Assoc, Flagstaff, Ariz). C, A computed tomography scan at 3 months showed a small but appreciable “bird’s beak” without endoleak or graft collapse. The superimposed “wedge” symbol outlines the “bird’s beak.” D, The patient, however, presented at 5 months with a recurrent pseudoaneurysm due to endograft collapse (arrow). E, He was treated with repeat endografting with good initial result, but ultimately required graft excision and open reconstruction for aortoesophageal fistula.
Discussion
Traditional open repair of TAT involving thoracotomy, aortic cross-clamping, and in some cases left heart bypass is a highly invasive and morbid procedure. Respiratory compromise from lung and chest wall injuries is compounded by thoracotomy, and aortic cross-clamping and unclamping complicate pre-existing hemodynamic and cardiac instability in these critically injured patients. Paraplegia, the most feared complication of any elective thoracic aortic procedure, becomes an even more significant problem in the emergency setting of trauma.
For these reasons, up to a third of trauma patients who arrive at a hospital alive with TAT die before they are deemed fit for open aortic surgery.12 The mortality rates for those who do undergo operation approach 30%.5 A variety of technical improvements, including the use of shunts for distal perfusion and cardiopulmonary bypass, seem to have decreased the mortality rate of this operation in some cases13; but overall, open thoracic aortic surgery in these trauma victims remains a daunting undertaking.
Delaying aortic repair in those who otherwise would not tolerate immediate surgery is often the only alternative. In fact, when this delay is judiciously applied, it may actually improve survival after aortic surgery in selected cases where immediate operation in a patient with other life-threatening injuries would likely result in death.14, 15 This delay, of course, comes at a cost: some patients with untreated TAT may progress to exsanguination before undergoing repair.3
The advent of TEVAR for the treatment of TAT promises to avoid many of the complications associated with open thoracic aortic repair. It therefore may allow surgeons to offer this treatment to more critically ill aortic transection patients that previously might not have tolerated open repair and avoid having to delay repair of an injury that leaves patients in a tenuous state while uncorrected.
Although TEVAR has only been approved for the treatment of degenerative aneurysmal disease, applications for other pathologies are emerging, including dissections and TAT. Advantages of this application of TEVAR include avoidance of thoracotomy, aortic cross-clamping, and left heart or cardiopulmonary bypass, all major sources of morbidity and death after open repair. In most cases, TEVAR also requires considerably less time than open repair and can be done expediently in relatively unstable patients.
Previously published studies of stent grafting for aortic transection consist of case reports and small series, but all consistently demonstrate that this application of TEVAR is a feasible alternative to open repair. Reported immediate technical success rate is virtually 100% in the literature, with very low paraplegia rates.
Tehrani et al6 and Hoornweg et al7 published series of 30 and 28 patients, respectively, without incidence of procedure-related death or paralysis.6, 7 A series of 20 patients was recently published by Neschis et al,16 with results similar to the present series. They reported one endoleak, one graft collapse, and no procedure-related deaths, although four patients in their series died from other injuries.
Amabile et al17 published a series of 20 patients with TAT, of whom nine were treated with TEVAR and 11 with open surgery, including direct repair or aortic replacement and cardiopulmonary bypass. The technical success rate in their endovascular group was 100%, without any procedure-related death or morbidity, including paralysis, although one patient died after an open surgery. They concluded that the immediate outcome after endovascular aortic transection repair was at least as good as open repair.
The present series also demonstrated a high immediate technical success rate, with only one procedure-related complication. During the same time period, 43 patients underwent open repair in our institution, eight (18.6%) of whom died in the perioperative period. Care should be taken in making this comparison, however, because this is only a retrospective review of the TEVAR patients. To our knowledge, this is the first report of the application of TEVAR for TAT in both the acute and subacute stages of injury. Thus, endovascular repair of traumatic transection seems to be a flexible treatment option that can be used immediately after injury in critically ill patients or in a delayed fashion in selected patients.
However, as in the setting of endovascular repair for degenerative thoracic aneurysms, potential complications unique to stent grafting must be taken into consideration when applying this technique to repair TAT. Type 1 and type 2 endoleak associated with left subclavian coverage are well documented in the literature as are the incidences of stent graft collapse or migration.11, 16, 18, 19, 20, 21, 22, 23 Although no endoleaks were identified on completion arteriography in the current study, a small type 1 endoleak was detected on a postoperative CT scan that spontaneously resolved by the 1-month follow-up. The lone late graft-related complication in this series was indeed a stent graft collapse that resulted in serious complications.
Thoracic endograft collapse is often related to graft oversizing, a problem inherently associated with the smaller aortic diameters of relatively young trauma victims. Indeed, several cases of thoracic endograft collapse after TAT repair have been reported.16, 20, 21, 22, 23 The mean aortic diameter of patients with traumatic aortic injury was 19.3 mm in one study24; however, currently available endografts in the United States do not accommodate such small aortas. The smallest TAG device accommodates a 23-mm aorta and the smallest TX2 device a 24-mm aorta. Deploying these grafts into a small aorta inevitably results in folding of the graft material at the proximal edge and thus poor apposition.
In addition, the acute angle of the transverse arch combined with poor conformability of the grafts causes a “bird’s beak” phenomenon in reference to the elevation of the proximal portion of the graft from the lesser curve of the aorta. Vector forces exerted onto this area cause cantilevering effects and may collapse the graft25 as observed in our series. This patient did not receive an oversized device, but did have a “bird’s beak” on completion angiogram and on a CT at 3 months. Anecdotally, it was thought that the collapses occur early after implantation, but a review of the literature suggests that the timing of collapse is highly variable, ranging from days to 6 months. The timing noted in this series falls within the reported range.
Because the left subclavian artery is close to the transection, it often must be covered for an adequate proximal sealing zone. Although this is innocuous in most cases, it should be avoided in certain situations, such as left internal mammary-to-coronary bypass, left axillary-to-femoral bypass, or in the setting of a dominant left vertebral artery. Left subclavian coverage in the setting of prior aortic surgery may also increase the risk of postoperative spinal cord ischemia. In such cases, left subclavian artery revascularization should be performed to preserve the anterior spinal artery and other collateral flow to the spinal cord.26, 27
Smaller sizes of the aorta and external iliac arteries in this relatively young group of patients may also cause access vessel injury or, as already mentioned, crimping of the graft when deployed. Some authors9, 28, 29 have thus recommended aortic extension cuffs designed for use in the infrarenal aorta as a smaller diameter alternative to thoracic devices designed for an aneurysm. The short lengths of these cuffs, however, often require multiple segments to provide enough coverage, predisposing to type 3 endoleaks.
Systemic heparinization was used in all patients in this study for the short duration of time that the access sheaths were in place to prevent lower extremity arterial thrombosis, and it was reversed at the completion of the procedure. This did not contribute to overall significant blood loss in this series. TEVAR without heparinization has been reported6, 7 and would be indicated in the management of TAT with intracranial bleeding or other hemorrhagic injuries.
The need for rigorous long-term follow-up, including multiple CT scans, can be an issue in this patient population with traditionally poor follow-up rates. Finally, the long-term durability of these stent grafts in patients who are typically only in their third or fourth decade of life will need to be established before TEVAR can completely replace open aortic repair for TAT. In that regard, TEVAR may serve a role of a bridge graft in the management of TAT as a temporizing measure for those who develop persistent pseudoaneurysm or other graft-related complications. We do not yet espouse routine open conversion after TEVAR.
Conclusion
TEVAR promises to be a viable alternative to open surgical repair in a variety of the situations that trauma patients often face. It can be performed with less risk of exacerbating pulmonary injuries than a thoracotomy and can be completed more expeditiously in unstable patients than open repair. Furthermore, as demonstrated by the current series, delayed repair can be done safely and effectively in selected patients with TAT. Continued surveillance is needed to define long-term outcomes in this group of young patients.
Author contributions
References
- . Nonpenetrating traumatic injury of the aorta. Circulation. 1958;17:1086–1101
- . The mechanism of injury in blunt traumatic rupture of the aorta. Eur J Cardiothorac Surg. 2002;21:288–293
- Prospective study of blunt aortic injury: Multicenter Trial of the American Association for the Surgery of Trauma. J Trauma. 1997;42:374–380
- . Traumatic rupture of the aorta. Surg. 1959;46:787–791
- . Rupture of thoracic aorta caused by blunt trauma (A fifteen-year experience). J Thorac Cardiovasc Surg. 1990;100:652–660
- Endovascular repair of thoracic aortic tears. Ann Thorac Surg. 2006;82:873–877
- Endovascular management of traumatic ruptures of the thoracic aorta: a retrospective multicenter analysis of 28 cases in The Netherlands. J Vasc Surg. 2006;43:1096–1102
- Blunt traumatic aortic transection: the endovascular experience. Ann Thorac Surg. 2003;75:106–111
- . Percutaneous endovascular repair of blunt thoracic aortic transection. J Trauma. 2005;59:1062–1065
- . Endovascular repair of traumatic descending aortic transection. J Endovasc Ther. 2002;9:573–578
- Endovascular treatment of thoracic aortic aneurysms: results of the phase II multicenter trial of the GORE TAG thoracic endoprosthesis. J Vasc Surg. 2005;41:1–9
- . Traumatic aortic rupture: twenty-year metaanalysis of mortality and risk of paraplegia. Ann Thorac Surg. 1994;58:585–593
- . Traumatic rupture of the thoracic aorta: cohort study and systematic review. J Vasc Surg. 2001;34:1029–1034
- Surgical indications and timing of repair of traumatic ruptures of the thoracic aorta. Ann Thorac Surg. 1998;65:461–464
- . Delayed treatment of isthmic aortic rupture. Cardiovasc Surg. 2000;8:280–283
- Twenty consecutive cases of endograft repair of traumatic aortic disruption: lessons learned. J Vasc Surg. 2007;45:487–492
- . Surgical versus endovascular treatment of traumatic thoracic aortic rupture. J Vasc Surg. 2004;40:873–879
- Endoleaks after endovascular repair of thoracic aortic aneurysms. J Vasc Surg. 2006;44:447–452
- . Endovascular stent grafting versus open surgical repair of descending thoracic aortic aneurysms in low-risk patients: a multicenter comparative trial. J Thorac Cardiovasc Surg. 2007;133:369–377
- . Anatomic factors associated with acute endograft collapse after Gore TAG treatment of thoracic aortic dissection or traumatic rupture. J Vasc Surg. 2007;
- . Symptomatic collapse of a thoracic aorta endoprosthesis. J Vasc Surg. 2006;43:1270–1273
- . Collapse of a stent-graft following treatment of a traumatic thoracic aortic rupture. J Endovasc Ther. 2005;12:503–507
- Endovascular repair of proximal endograft collapse after treatment for thoracic aortic disease. J Vasc Surg. 2006;43:609–612
- Angiographic description of blunt traumatic injuries to the thoracic aorta with specific relevance to endograft repair. J Endovasc Ther. 2002;9(Suppl 2):II84–II91
- Midterm results of endovascular repair of descending thoracic aortic aneurysms with first-generation stent grafts. [see comment] J Thorac Cardiovasc Surg. 2004;127:664–673
- Risk of spinal cord ischemia after endograft repair of thoracic aortic aneurysms. J Vasc Surg. 2001;34:997–1003
- . Risk factors of neurologic deficit after thoracic aortic endografting. Ann Thorac Surg. 2007;83:S882–S889
- . Endograft stenting in the adolescent population for traumatic aortic injuries. J Pediatr Surg. 2006;41:e27–e30
- . Blunt traumatic aortic transection: endoluminal repair with commercially available aortic cuffs. J Vasc Surg. 2003;38:1132–1135
Competition of interest: Michel S. Makaroun, MD, has a consulting agreement with W. L. Gore, Cardiomems, and Cook. He has research support from W. L. Gore, Cardiomems, Cook, Cordis, and Abbott.
PII: S0741-5214(07)01185-8
doi:10.1016/j.jvs.2007.06.049
© 2007 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
