Endoluminal stent–graft placement for acute rupture of the descending thoracic aorta

D Scheinerta,*, H Krankenbergb, A Schmidta, J.F Gummertc, S Nitzsched, S Scheinerta, S Bräunlicha, I Sorged, R Krakorc, G Biaminoa, G Schulera and F.W Mohrc

a Department of Medicine/Cardiology, Clinical and Interventional Angiology, University of Leipzig – Heart Centre, Strümpellstr. 39, 04289 Leipzig, Germany
b Centre for Cardiology and Vascular Intervention, Germany
c Department of Cardiovascular Surgery, University of Leipzig –Heart Centre Strümpellstr. 39, 04289 Leipzig, Germany
d Department of Radiology, University of Leipzig – Heart Centre Strümpellstr. 39, 04289 Leipzig, Germany

Received November 20, 2003; revised February 9, 2004; accepted February 19, 2004 * Corresponding author. Tel.: +49-341-8651458; fax: +49-341-8651488
E-mail address: dierk.scheinert{at}gmx.de


    Abstract
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 
Aims To investigate the results of endovascular stent–graft placement for the treatment of acute perforating lesions of the descending thoracic aorta.

Methods and results A total of 31 consecutive patients underwent interventional treatment for perforating lesions of the descending aorta. In 21 cases (group A), the aortic perforation was due to rupture of a descending thoracic aneurysm or dissection, whereas 10 patients (group B) were treated for traumatic transection of the descending aorta. A total of 42 endoprostheses were implanted.

The implantation procedure was successful in all cases without peri-interventional complications. In one case, implantation of a second endoprosthesis became necessary due to type I endoleak. Overall, the 30-day mortality was 9.7%. As all three deaths occurred in group A, the mortality rate in this group was 14.3% versus 0% in group B. Similarly, postinterventional complications were more prevalent, with 28.6% in group A (renal failure ; stroke ) versus 10.0% in group B (renal failure ). No paraplegia and no further deaths or ruptures occurred during follow-up (mean 17 months).

Conclusion Interventional stent–graft placement is an effective treatment option for the emergency repair of descending aortic perforations.

Key Words: Aneurysm • Aorta • Stents • Mortality


    Introduction
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 
Endovascular stent–graft placement has been described as a treatment alternative for aneurysms and dissections involving the descending thoracic aorta. Although data from large randomised trials are pending, the technique is generally considered to be an effective and less invasive treatment option in patients with suitable morphologic conditions.1,2 Particularly for elderly patients with significant comorbidity, this minimally invasive approach to aortic repair seems to be associated with less procedure-associated mortality and morbidity.

The results of elective endovascular stent–graft procedures for the repair of thoracic aortic aneurysms or type B aortic dissections have been reported by several groups, but the potential of this technique for emergency repair of descending aortic perforations has only been examined in small numbers of cases.3–11 As the surgical complication rate is high in these patients, the percutaneous approach may be particularly beneficial. The present study details our experience with endovascular stent–graft placement performed in 31 patients with acute perforation of the descending aorta.


    Methods
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 
Between January 1999 and October 2003, in our institution 31 patients (19 men, 12 women, mean age 62.1 years) underwent stent–graft repair of descending aortic perforations. Whereas 10 patients entered our hospital directly through the emergency unit, the majority of patients () were admitted after thoracic aortic rupture was diagnosed in the referring hospital. All patients had a history of acute thoracic pain or traumatic injury within 24 h prior to admission. According to the aetiology of the perforating lesion, patients were subdivided in two groups: Group A comprised 21 patients with ruptured aneurysms () or dissections and penetrating ulcers () of the descending thoracic aorta. Group B consists of 10 patients treated for acute traumatic transection of the descending aorta. Table 1 details the baseline clinical data of all study individuals. Clearly, the patients in group B treated for traumatic lesions were significantly younger. Comorbidity in this group was mainly trauma-associated, and medical comorbidity was less prevalent than in group A.


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Table 1 Baseline clinical and lesion characteristics of the patients

 
A detailed list of associated traumatic injuries in group B is given in Table 2. The injury severity score (ISS) was calculated for each patient12 and showed a mean value of 25.4±17.5.


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Table 2 Associated traumatic injuries for patients with traumatic aortic transsection (Group B)

 
All patients underwent contrast-enhanced spiral computed tomography prior to the intervention. During this investigation, 100–120 mL nonionic contrast medium (Imeron 350, Bracco-Byk Gulden, Konstanz, Germany) was used. Aortic rupture was defined as disruption of the aortic wall showing fresh blood outside the adventitia, which was documented in all patients. A significant haemorrhagic mediastinal or pleural effusion was present in 25 cases (Group A, ; Group B, ). In one of these patients, concomitant oesophageal bleeding due to an aortic rupture with development of an aorto-oesophageal fistula was observed. Another patient showed active bleeding from an aorto-tracheal fistula (Figs. 1 and 2).



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Fig. 1 Acute rupture of a chronic descending thoracic aortic aneurysm with mediastinal contrast extravasation (Rupt) and relevant haemorrhagic mediastinal and pleural effusion (a). Complete thrombosis of the mediastinal haematoma after sealing the perforation by implantation of a stent–graft prosthesis (b).

 


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Fig. 2 Two-dimensional CT-reconstruction (multi-planar reconstruction) before: (a) and after successful stent–graft repair (b) of an aortic rupture (LAO-like view, reconstruction axis varies slightly because of variations in the patient's position).

 
Endovascular procedure
Intensive medical therapy with antihypertensive drugs was initiated in patients with hypertensive conditions immediately after aortic rupture was diagnosed. A total of 21 patients presented initially with signs of haemorrhagic shock, defined as persistent systolic blood pressure 90 mm Hg and heart rate 100 bpm. In these cases, substitution with blood components (packed erythrocytes, fresh frozen plasma) and crystalloid fluids was performed prior to the intervention.

All stent–graft procedures were carried out in the angiography suite under general anaesthesia. Using a left brachial approach, a 5-French angiographic pigtail catheter was advanced into the ascending aorta. This catheter allows contrast injection during the procedure and helps to identify the origin of the left subclavian artery, which is an important anatomic landmark for positioning the stent–graft. On average, 67 mL of nonionic contrast medium (range 40–115 mL, Imeron 350) was used.

For insertion of the stent–graft, the common femoral artery was surgically exposed. In six patients the femoral artery was considered inappropriate due to its small calibre or the presence of severe calcification. In these cases the common iliac artery was cannulated using an extraperitoneal surgical access. After achieving vascular access, 5000 U of heparin sodium was administered intravenously. To facilitate delivery of the stent–graft to the thoracic aorta, an ultrastiff guidewire (Meyer Extra Back-up. 035 in.x300 cm) was used.

A total of 42 endoprostheses were implanted in 31 patients. Whereas sufficient coverage of the lesion could be achieved with one endoprosthesis in 22 patients (covered length 10–13 cm), seven patients required two endoprostheses and two patients required three endoprostheses to completely seal the perforation site. The diameter of the endoprostheses ranged from 24 to 46 mm. Patients with traumatic injuries (Group B) required implantation of smaller devices (range 24–34 mm) than patients in group A (range 32–46 mm).

In our series, two different stent–graft designs were used. In 29 patients the Talent device (Medtronic, World Medical Manufacturing Corp., Sunrise, FL) was implanted. This self-expanding endoprosthesis consists of circumferential nitinol stent springs arranged as a tube to conform to the lumen and covered on the outside with a Dacron graft. For implantation, the Talent endoprosthesis is compressed in a polytetrafluoroethylene (PTFE) sheath with an outer diameter of 22–27 French. For deployment, the endoprosthesis is held in position with a pusher while the sheath is withdrawn.

In two cases, the Excluder system (Gore, Sunnyvale, CA) was used. The endoprosthesis is made up of an ultra-thin ePTFE graft with an outer self-expanding nitinol support structure. The endoprosthesis is mounted on a catheter-based delivery system and once the system is positioned in the desired location the stent–graft is deployed by pulling back a string attached to the graft.

In all cases, postdilatation with a compliant aortic balloon catheter (Reliant, Medtronic, World Medical Manufacturing Corp, Sunrise, FL) was performed in the section covered by endoprostheses to achieve optimal alignment of the graft material with the vessel wall.

Follow-up imaging
The follow-up protocol included contrast-enhanced CT scanning performed within 72 h after the stent–graft procedure to test the seal of the perforation and to assess the perfusion of the branch vessels. Spiral CT scans were then obtained 6 months after the stent–graft procedure and thereafter yearly and at the onset of any new symptoms.

Statistical analysis
Each categorical factor is described as the number and percentage of patients. Continuous variables are presented as mean ± standard deviation (SD) values, if appropriate. In case of a nonGaussian distribution, median and range values are given.

The terms early mortality and morbidity refer to complications occurring within 30 days after the endovascular procedure. This information could be obtained for all study subjects.


    Results
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 
Technical success
The mean time between the diagnosis of aortic rupture and endovascular repair was 32.3±24.3 h. Implantation of the stent–graft prosthesis was successfully performed in all cases without peri-interventional complications. On average, 31 min after beginning surgical cutdown, implantation of the endoprosthesis was completed. The postinterventional angiography demonstrated that all lesions were fully covered by the endoprosthesis with no detectable extravasation of contrast media. In six patients this was achieved by intentionally covering the left subclavian artery.

Despite these angiographic findings, in three cases a small amount of contrast medium was observed to be leaking on the late-phase, contrast-enhanced, spiral CT images. In the first case, a partial residual perfusion of a thoracic pseudoaneurysm through the graft material was detected 48 h after the intervention. A second CT scan performed 6 days later demonstrated complete thrombosis of the pseudoaneurysm without further treatment. In the second patient, who was treated for a pseudoaneurysm, residual perfusion of the target lesion was detected during two postinterventional follow-up CT scans without a clear localisation of the leak. As there was a tendency towards pseudoaneurysm shrinkage and thrombosis, the patient was treated conservatively under the assumption that complete thrombosis of the lesion could be achieved. However, the third postinterventional CT scan, performed 18 days after implantation, demonstrated a clear expansion of the false aneurysm. At this time a type I endoleak at the distal end of the prosthesis was evident. To achieve complete sealing, a second stent–graft prosthesis was implanted distally with an overlap of 3–4 cm. The spiral CT performed on the next day showed complete thrombosis of the lesion. In the third case, a patient with an aorto-tracheal fistula due to a penetrating aortic ulcer, the postinterventional CT scan demonstrated a proximal type I endoleak. Although the patient was haemodynamically stable and showed no clinical signs of bleeding, the decision was taken to extend the proximal coverage of the lesion by implantation of a second endoprosthesis. However, 1 h after the CT scan made before implanting the second endoprosthesis, the patient died of acute tracheal bleeding.

Early mortality
In the early postinterventional phase, three of the 31 patients died, yielding an early mortality rate of 9.7%. In the case described above, death was related to recurrence of the aortic rupture. The other two patients had a complicated course in the intensive care unit. One patient developed acute respiratory distress syndrome secondary to severe pneumonia. The second patient died on day 13 with multi-organ failure due to a cardiac low-output syndrome. As all deaths occurred in group A, the mortality rate of this group was 14.3% versus 0% in group B.

Early morbidity
Acute renal failure requiring haemodialysis occurred in five patients (16.1%). In three cases this had to be considered a deterioration of chronically impaired renal function (preinterventional creatinine values were elevated to 1.5 mg/dL), whereas in the other two patients preinterventional renal function was normal. In three cases renal function improved after a mean of 9.3 days. The remaining two patients required haemodialysis for more than 30 days.

In two patients, acute ischaemic stroke was observed postinterventionally. One patient experienced right hemiparesis that resolved partially in the following weeks. In the other case the CT scan demonstrated an ischaemic lesion of the pons that resulted in contralateral hemiplegia and ipsilateral facial paresis. There were no cases of spinal cord ischaemia or paraplegia. Again, postinterventional complications were more prevalent in group A (renal failure, ; ischaemic stroke, ), with an incidence of 28.6% versus 10.0% in group B (renal failure, ).

Finally, out of the six patients in which the left subclavian artery was intentionally covered, one patient developed symptomatic subclavian steal syndrome and underwent elective transposition of the left subclavian artery 8 weeks after the stent–graft procedure.

Late survival and complications
No further deaths occurred during the median follow-up time of 15 months (range 3–36 months). In one patient, treated for a ruptured pseudoaneurysm related to a type B aortic dissection, a newly developed, asymptomatic, type A dissection was detected in the routine 3-month CT scan. The patient underwent immediate surgical reconstruction of the ascending aorta and aortic arch with anastomosis of the arch prosthesis to the endoprosthesis in the descending aorta. During the surgical procedure, a new entry tear in the ascending aorta about 2 cm from the aortic valve was identified as the underlying lesion. Retrospectively, an intramural haematoma in the ascending aorta was found, which was diagnosed before stent–graft implantation could have been a predisposing condition for the development of this type A dissection. The postoperative course was uneventful and there were no further events during follow-up. In the remaining patients, serial spiral CT scans confirmed the absence of rupture or leaks.


    Discussion
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 
Acute rupture of the descending aorta is a catastrophic condition that, if left untreated, almost invariably has a lethal outcome. The mortality associated with surgical treatment of descending aortic perforations is largely dependent on the aetiology and extent of the aortic lesion. Whereas mortality rates of 14–28% have been reported for surgical repair of traumatic aortic rupture,13–16 ruptured thoracic aneurysms and aortic type B dissections complicated by perforation or end-organ failure have a surgical mortality rate exceeding 50%.17–19

Endovascular therapy by implantation of thoracic stent grafts has been shown to be a valuable technique for the treatment of thoracic aortic aneurysms and type B aortic dissections.1,2 Considering the relatively short procedural time and minimally invasive approach of this technique, it has excellent potential for use in emergency cases with contained or active bleeding from perforation sites in the descending aorta. Several authors have reported experiences of single cases and small series of patients treated for acute aortic rupture by implantation of stent–grafts.3–11,20,21

The present study details the results of 31 consecutive patients undergoing emergency endovascular treatment for acute penetrating lesions of the descending aorta. In all cases the implantation procedure was uneventful and the endoprosthesis could be reliably positioned to cover the tear in the aortic wall.

As intraprocedural angiographic visualisation of the aortic tear is sometimes difficult, additional imaging techniques may be required. Some authors have suggested intraoperative transoesophageal echocardiography or intravascular ultrasound22,23 for detection of the tear in the aortic wall. Although we used these techniques in a considerable number of our cases, they are not always available, particularly in emergency situations. In our practice, planning of the procedure including localisation of the target rupture site as well as sizing of the endoprosthesis according to the aortic diameters proximal and distal to the lesion. Sizing was reliably performed using the preinterventional contrast-enhanced spiral CT images.

Furthermore, contrast-enhanced spiral CT was found to be more accurate than angiography in detecting small endoleaks, which were found in three patients. The clinical significance of these findings is difficult to determine. Small perigraft leaks despite sufficient coverage of the lesion may be due to residual folding of the graft material and have the tendency to thrombose spontaneously. Furthermore, in some patients we observed extravasation of contrast media through the graft material, which always disappeared in 7 days. This is a well-known shortcoming of the porous Dacron mesh, which requires platelet adhesion and local clot formation to tighten the graft material. In contrast, a type I endoleak, which was seen in two of our patients, has to be considered a treatment failure. In patients with contained or open aortic rupture, this is a life-threatening condition that requires urgent endovascular or open surgical revision.

The overall mortality in our series was 9.7%, and all fatal events occurred in the first 30 days after the intervention. Aside from one patient with proximal type I endoleak who died from acute aortic rupture, all other deaths were due to medical complications that were refractory to intensive medical care.

Differentiating the results according to the aetiology of the aortic rupture, optimal results with 100% survival could be achieved in the group of patients with traumatic aortic transection. Despite the fact that these patients had multiple traumatic injuries, they were significantly younger and had fewer medical comorbidities. In contrast, all deaths occurred in patients treated for ruptured aortic aneurysms or dissections. Furthermore, with an incidence of 28.6% versus 10.0%, relevant postinterventional complications, including renal failure and ischaemic stroke, were more prevalent in this group. Chronically impaired renal function was found to be a major risk factor for acute postinterventional renal failure, which occurred in three out of six patients with baseline creatinine 1.5 mg/dL. Other factors, including the total amount of contrast media and haemodynamic variables, could have contributed to the occurrence of renal failure; however, no relationship could be demonstrated in this series. Ischaemic stroke was observed in two patients of group A, suggesting that a chronically diseased aorta with severe atherosclerotic changes may be a predisposing condition to embolisation during deployment of the endoprosthesis. Nevertheless, irrespective of the cause of rupture, the procedure-associated mortality and morbidity for all patients was substantially lower than the results cited in the surgical literature.13–19,24

Paraplegia is a known neurologic complication of surgical repair of lesions in the descending aorta. Despite advances in surgical techniques, with reimplantation of intercostal arteries and shortened cross-clamping times, this complication occurs in approximately 7–17% of cases.1,14,16,24 In a randomised comparison of stent–graft treatment with conventional surgery for patients with type B dissections, Nienaber et al.1 were able to obtain a significantly lower paraplegia rate of 0% versus 17% after interventional treatment. A similar result was achieved in our series. Thus, preservation of the integrity of the aorta, as opposed to aortic clamping and operative graft insertion, seems to be important for protecting the spinal arteries. However, the absence of paraplegia must be considered cautiously because our series is small in comparison to the large surgical series previously documented.

In previous publications, one major drawback to the widespread use of endovascular repair for acute aortic rupture was the availability of suitable stent–graft devices. Several authors used homemade devices, which resulted in excessive delay before endovascular repair due to the time required for fabrication and gas sterilisation. In a series of Semba et al.,5 a mean of 30 h was required to make and sterilise the devices. Currently, standardised endoprostheses ranging from 24 to 46 mm in diameter and a coverage length of approximately 115 mm are commercially available (Talent, Medtronic, World Medical Manufacturing Corp, Sunrise, FL). With approximately 10 stent–grafts of various diameters in stock, we were able to treat all emergency patients immediately after the patient entered the hospital.

Other important concerns when analysing the feasibility of endovascular treatment of thoracic aneurysms are the status of peripheral access vessels and the morphologic suitability of the aneurysmal lesion. Generally, stenosis, the severe calcification and tortuosity of the iliac vessels, or an access-vessel diameter of less than 8 mm can impede the introduction of the 22-F to 27-F device. Therefore, we always obtained an angiographic image of the pelvic arteries prior to arterial cutdown to identify the optimal access site. In case of unsuitable conditions in the groin, extraperitoneal exposure and cannulation of the common iliac artery seems to be a safe access alternative.

With regard to the morphology of the aortic lesion, a proximal neck of >=15 mm is considered optimal. However, several cases of intentional coverage of the left subclavian ostium have been reported.25,26 In our experience, the left subclavian artery was intentionally covered in six cases without major adverse events. Only one patient developed a symptomatic subclavian steal syndrome and underwent elective transposition of the left subclavian artery 8 weeks after the stent–graft procedure. In our series, extension of bare springs into the aortic arch did not cause any complications. In one case, asymptomatic type A dissection became evident during a follow-up CT at 3 months. Surgical exploration, however, clearly revealed an entry tear in the ascending aorta as the cause of this dissection. There were no signs of perforation or dissection related to the bare springs.


    Study limitations
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 
Major limitations of the study are its retrospective nature and the lack of a control group. Furthermore, although this is one of the largest series of consecutive patients interventionally treated for acute aortic rupture, the small absolute number of patients and unequal distribution into the two study groups do not allow statistically significant conclusions to be drawn.


    Conclusions
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 
The results of this initial series of 31 consecutive patients with acute descending thoracic aortic ruptures treated by endoluminal stent–graft placement suggest that this endovascular approach is an alternative to open surgical management. The reported results, achieved with an optimal multi-disciplinary approach involving endovascular specialists, cardiac surgeons, radiologists and anaesthesiologists, are promising and may improve the prognosis of this high-risk patient population. However, it remains to be determined if the promising initial results of this novel endovascular technique will be confirmed by long-term follow-up.


    References
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 Study limitations
 Conclusions
 References
 

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