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ORIGINAL ARTICLE |
Department of Cardiac Thoracic & Vascular Surgery National University Hospital Singapore
Atasha Asmat, AFRCS, Tel: +65 67722060, Fax: +65 67766475, Email: Atasha_ASMAT{at}nuh.com.sg, Department of Cardiac, Thoracic & Vascular Surgery, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074., Disclosure: Peter Ashley Robless, FRCS, is an Endovascular Proctor for Cook Medical, Inc., Australia.
ABSTRACT
The conventional treatment of traumatic thoracic aortic transection is open surgical repair but it is associated with high rates of morbidity and mortality, particularly in patients with multiple injuries. We reviewed our experience of endovascular repair of traumatic thoracic aortic transection. Between March 2002 and December 2007, 7 patients (male 6, female 1; mean age 40 years) with multiple injuries secondary to blunt trauma underwent endovascular stenting. One patient required adjunctive surgery to facilitate endovascular stenting. Mean intensive care unit stay was 8.6 days (range, 3–16 days). Arterial access in all patients was obtained by femoral cut-down. The mean operating time was 122 min. Technical success was achieved in all cases. There was no mortality. One patient suffered a right parietal stroke, but none developed procedure-related paralysis. The mean follow-up period was 18.6 months (range, 6–48 months). There was no evidence of endoleak, stent migration, or late pseudoaneurysm formation on follow-up computed tomography. Endovascular stents can be used to treat traumatic thoracic aortic transection, with low rates of morbidity and mortality. Although early and midterm results are promising, the long-term durability of endovascular stenting for traumatic thoracic aortic transection remains unknown.
Key Words: Aorta • Thoracic • Aortic Rupture • Blood Vessel Prosthesis • Stents • Thoracic Injuries
INTRODUCTION
Traumatic thoracic aortic rupture (TAR) is a life-threatening complication of blunt chest trauma, with a mortality rate approaching 85%.1 The first successful primary repair of acute TAR was described in 1959.2 Since then, the standard treatment has been open surgical repair. However, TAR is rarely an isolated injury, associated injuries are often serious, and the patient may be compromised by various aspects of standard surgical repair of the aorta, which include thoracotomy, single-lung ventilation, systemic anticoagulation, cardiopulmonary bypass, and aortic cross-clamping. In 1991, Parodi and colleagues3 described their first clinical experience of endovascular stenting in abdominal aortic aneurysms. This technology was subsequently utilized in the management of thoracic aortic pathology, with promising results.4 There has since been a growing interest in stent grafting as an alternative to conventional surgery, with an increasing number of reports of successful endovascular treatment of TAR.5–7 We report our experience of emergency treatment of acute TAR, using endovascular stent grafts.
PATIENTS AND METHODS
We performed a retrospective review of all patients undergoing endovascular repair of TAR between March 2002 and December 2007 in our hospital. No patients with TAR were managed by open surgical repair during this period. There were 7 patients with a mean age of 40 years (range, 19–66 years), comprising 6 (86%) men and 1 (14%) woman. All injuries were due to blunt trauma from rapid deceleration. All patients sustained multiple injuries including rib fractures with concomitant pulmonary contusions, extremity fractures, and solid organ injury (Table 1
). Based on the mechanism of injury or the abnormalities seen on the initial chest radiograph, further investigations using computed tomography (CT) were carried out (Figure 1). All patients with evidence of TAR on CT underwent early endovascular repair following a period of stabilization.
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). The guidewire was exchanged for a Lunderquist guidewire (Cook, Australia) via the femoral sheath. The 20F–24F stent graft (Cook Zenith TX2, or Gore TAG) was inserted under fluoroscopic control over the stiff guidewire. The mean distance between the left subclavian artery and the transection was 2 cm. The sheathed stent graft was advanced until the tip was just proximal to the site of transection, and deployed without the use of pharmacologically induced cardiac arrest or hypotension. Following deployment, check angiograms were performed to assess the position of the stent graft (Figure 3). Using measurements of the aortic lumen diameter recorded by preoperative CT, we determined the diameter of the device to be used in each patient. The devices were oversized by approximately 10% to 15%. In one patient, preoperative CT demonstrated the site of transection to be in close proximity to the origin of the left common carotid artery. To ensure an adequate proximal seal, the left common carotid artery was bypassed to the right common carotid artery before endovascular repair. The origin of the left common carotid artery and left subclavian artery were covered with the stent-graft. Following endovascular repair, all patients underwent CT angiography within 1 week, and at 6- to 12-month intervals thereafter.
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The mean time from diagnosis to endovascular stenting was 8.4 h (range, 2–21 h). Data on the diameter of the thoracic aorta and the sizes of stent grafts used are given in Table 2. Technical success was achieved in all patients; this was defined as angiographic evidence of exclusion of TAR. The mean operating time was 122 min. There was no perioperative mortality. One patient who had a nonhemorrhagic brain contusion preoperatively, developed a right parietal stroke in the postoperative period, and has since made a full recovery. No patient developed procedure-related paralysis or contrast-induced nephropathy. The mean follow-up in these patients was 18.6 months (range, 6–48 months). During follow-up, there was no evidence of endoleak, stent migration, or late pseudoaneurysm on clinical examination and CT imaging.
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TAR is the second most common cause of death from blunt trauma, after head injury.8 In more than 80% of cases, it results in immediate death. Patients who survive usually have associated multiple and severe injuries. The standard of care for TAR has been early surgical repair using various techniques, such as clamp-and-sew or shunting, under partial or full cardiopulmonary bypass. Despite advances and refinement of surgical techniques, the morbidity and mortality of early surgical repair of TAR remains high, and ranges from 15% to 30% in contemporary studies.8,9 Some reports have advocated a delay in the surgical treatment of TAR in stable patients, with close arterial pressure monitoring. However, the possible benefits of this management strategy are negated when one considers that 2% to 5% of these patients develop secondary rupture, mostly within one week of the initial injury.9–12 In our study, all patients underwent immediate endovascular repair after radiographic evidence of aortic injury.
Since the initial description of endovascular treatment of thoracic aortic pathology with stent grafts, there have been several case reports demonstrating the feasibility of this technique.4,5,12–14 Our study shows that TAR can be safely and effectively managed with endovascular stent grafting. Presently, there are no available endografts designed specifically for TAR. Some complications related to endovascular stenting of TAR include collapse or infolding of the endograft.15 We used Cook or Gore stent grafts designed for thoracic aneurysm repair. The Zenith TX2 endograft is constructed of Dacron fabric supported by stainless steel Z-stents that prevent graft torsion or collapse. This device also has a covered proximal end with stainless steel barbs protruding through the graft fabric, which anchor the graft directly to the aortic wall and protect against distal stent graft migration during high-velocity systolic blood flow. The Gore TAG endograft is constructed of nitinol and PTFE, and it has been used for TAR in previous series.16
There are several advantages of endovascular repair over open surgical repair, including avoidance of a left thoracotomy incision, single-lung ventilation, systemic heparinization, and cardiopulmonary bypass in these critically injured patients. We also observed that operative times were shorter than those of conventional surgery. There were no incidences of procedure-related paralysis, which may be associated with the elimination of aortic crossclamping. A prospective randomized comparison of endovascular treatment and open surgical repair is difficult due to the low incidence of these injuries, but several small retrospective studies have attempted this. One study reported reduced procedural time, length of hospital stay, and operative mortality with the endovascular procedure compared to open surgical repair.17 Another study reported a mortality rate of 17% and paraplegia rate of 16% in 18 patients undergoing open surgery, whereas all 5 treated by endovascular repair survived without paraplegia.18 A more recent study reviewed 20 patients with TAR over a 6-year period; there was one early death among 11 who underwent open repair, but no deaths, paraplegia, or procedure-related complications in 9 who had endovascular repair, demonstrating that endovascular repair was at least as good as conventional surgery in the immediate perioperative period.19
Currently, there are no randomized controlled trials comparing endovascular procedures with open surgery for TAR. However, a recent review concluded that early results of endovascular repair of descending thoracic aortic pathology demonstrate a clear reduction in mortality over conventional open techniques, and this was particularly evident in the emergency setting.20 The ages of patients with TAR are lower than in those who present with aneurysmal disease, and the long-term outcome and durability of these endovascular devices remains unknown. These patients require long-term follow-up with CT angiography at frequent intervals. To date, our patients have suffered no endoleak, stent migration, or late pseudoaneurysm during follow-up. Thus it was concluded that the use of endovascular stent grafts to treat TAR is technically feasible and can be performed with low rates of morbidity and mortality. The early and midterm results are promising, and the long-term durability of endovascular repair of TAR is awaited.
ACKNOWLEDGMENTS
We would like to acknowledge the assistance of Dr Alexander Chao and Dr Mark da Costa in the preparation of this manuscript
REFERENCES
Asian Cardiovasc Thorac Ann 2009;
17:458-461
© 2009 by SAGE Publications
DOI: 10.1177/0218492309348624
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