Anastomotic False Aneurysms Research Articles

Abdominal Aorta Anastomotic False Aneurysm Leading to Double Focal Vertebral Body Erosion.

Anastomotic aortic false aneurysm with consequent erosion of vertebral bodies is a very rare event that needs prompt treatment. We report the case of a 71-year-old man with an aortobifemoral graft that was complicated by an uninfected proximal anastomotic pseudoaneurysm with double focal vertebral body erosion.

ВОЗМОЖНОСТИ ТРАНСПЛАНТАЦИИ СОСУДОВ В УРГЕНТНОЙ ХИРУРГИИ МАГИСТРАЛЬНЫХ АРТЕРИЙ

The article presents the experience of using allografts from a postmortem donor in emergency surgery of the main arteries of the lower extremities. Possible tactical methods of combined use of alloartery and allovein from various donors in urgent surgery have been demonstrated. High risks of interventions aimed at relieving early and late complications of vascular reconstructions remain an actual problem in angiosurgery. Very often, operations are performed in the presence of extensive necrosis and trophic ulcers (stage IV according to the Fontaine-Pokrovsky classification). Autovenous conduit from the great saphenous vein (type of arterial bed lesions C, D according to TASS II) was and remains the gold standard for choosing a shunt for reconstructive operations on infrainguinal arteries. In case of repeated reconstructions in the absence of a suitable autovein, in the presence of trophic ulcers and necrosis, an infectious process in the area of the vascular prosthesis, it is not always possible to use a synthetic prosthesis as a reliable alternative. Unsatisfactory results of using such materials dictate the need to choose a suitable graft. The problem of using allografts requires further advanced study. In this regard, the experience of using allografts in two non-standard urgent clinical situations is presented. The conclusion is made about the possibility of effective use of allografts from a postmortem donor in patients with bleeding after endovascular treatment of critical limb ischemia with trophic changes in the staged surgical treatment, as well as in patients with thrombosed anastomotic false aneurysms after previously performed surgical interventions.

Experience in treating patients with diabetes and anastomotic false aneurysm after reconstructive interventions in the aortic-femoral segment

The purpose of the work isto analyze and improve the results of treatment of patients with diabetes and anastomotic false aneurysm (FA) after reconstructive interventions. Materials and methods. The results of diagnostic examinations in 79 patients with 93 false anastomotic aneurysms were analyzed, the criteria of wound complication (hematoma, infiltrate), patency of shunts, bleeding, heart attack, stroke were evaluated. Among the patients there were 75 (94.9 %) men and 4 (5.1 %) women aged 40—75 years (mean age — (58.4 ± 2.9) years). 69 (87.3 %) patients underwent surgery for atherosclerotic lesions of the pelvic vessels and lower extremities, including 43 (54.4 %) patients with diabetes, 3 (3.8 %) — for abdominal aortic aneurysm, 4 (5.1 %) — after vascular injury, 3 (3.8%) — due to nonspecific aortic arteritis. A total of 79 patients underwent 93 reconstructive interventions. Results and discussion. The time of onset of clinical symptoms (pain, pulsation), which give reason to suspect the occurrence of FA, ranged from 8 days to 19 years: in 15 patients — less than 1 year, in 59 — up to 10 years, in 5 — up to 20 years. The average duration of FA formation after surgery is 62.5 months. The absence of pathological changes in the area of the proximal anastomosis and the presence of adequate outflow pathways in most cases allow us to limit the reconstruction of the distal anastomosis. Conclusions. Early diagnosis and surgical tactics for false anastomotic aneurysms in patients with diabetes can prevent complications and improve the results of surgical treatment. The optimal type of surgery for false aneurysms is their removal with re-prosthesis of the affected segment, which allows to save the limb and the patient's life. The use of modern pharmacological agents allows to reduce the progression of atherosclerosis, which is the main cause of false aneurysms. Dynamic ultrasound monitoring is required for patients who have undergone reconstructive vascular surgery.

Compliance of Textile Vascular Prostheses Is a Fleeting Reality

Compliance is considered to be a major property influencing the long term performances of synthetic vascular substitutes that could play a role in anastomotic false aneurysm and intimal hyperplasia stenosis onset. Over the last decades, manufacturers have tried to develop substitutes that mechanically mimic arterial properties and avoid a compliance mismatch at the anastomoses in particular. However, data are missing about how initial compliance properties could change with time. The goal of this study was to evaluate how the compliance of vascular grafts evolves under cyclic loading conditions invitro. The compliance of three different models of commercially available textile polyethylene terephthalate (PET) grafts was evaluated. Tests were performed with and without their original coating. Compliance was assessed with a specific device dedicated to measure the deformations undergone by a graft under cyclic pressure loading conditions, using image analysis software. In each experiment, image analysis was performed under 60 and 140mmHg pressure loading conditions at loading start (H0) and after three, six, and 24h (H3, H6, H24) loading time. Average radial, longitudinal, and volumetric compliance was calculated from the obtained images. Twenty-four samples were tested. Results demonstrate that all values decreased significantly within only a few hours. On average, the loss of compliance after 3h of cyclic loading ranged on average from 35% for longitudinal compliance to 39% for radial compliance and 37% (p<.050) for volume compliance. After 24h, the loss of radial, longitudinal and volume compliance was respectively 63±3%, 60.5±2% and 61±7%. In this invitro model, PET graft compliance has already decreased significantly within 3h. The rapid loss of compliance identified in this experimental study helps explain the mismatch mentioned in clinical observations.

Endovascular Repair of a Dacron Pseudoaneurysm in an Ascending-to-Descending Aortic Bypass.

In the setting of postcoarctation aortic repair, Dacron graft dilatation and late aneurysms are not uncommon. Reintervention usually involves redo open surgery and replacement of the aneurysmal graft or the pseudoaneurysmal suture line. The present case describes the endovascular repair of a Dacron anastomotic false aneurysm in an extra-anatomic ascending-to-descending aortic bypass, 19 years after surgical correction of aortic recoarctation.

Eversion Carotid Endarterectomy : A Short Review.

Carotid endarterectomy (CEA) is the main procedure in carotid surgery, as well as the most frequent vascular procedure. Two techniques of CEA are available : eversion and conventional plus patch angioplasty. Eversion CEA is anatomic procedure that reduces ischemic and total operative time. Simultaneous correction of the joined carotid kinking and coiling is possible, easy and safe, while the usage of patch is excluded. Thanks to oblique shape of anastomosis, eversion CEA is associated with low risk of long-term restenosis. The false anastomotic aneurysms occurrence is very rare, almost impossible after eversion CEA. However, the usage of carotid shunt during eversion CEA is not always simple, while proximal or distal extension of the carotid plaque can make eversion CEA more difficult and risky. Eversion CEA should be the first choice in carotid surgery. Conventional CEA is indicated in cases when carotid plaque is extended more than usual, as well as, if the usage of carotid shunt is necessary.

Repair of an Anastomotic Pseudoaneurysm with a Novel Hybrid Technique

Anastomotic false aneurysms are a late complication of aortic grafting. Treatment usually consists of débridement of the degenerated tissue and placement of a short interposition graft. In infectious situations, graft excision is required. An 80-year-old frail man with numerous comorbidities presented to clinic with an anastomotic pseudoaneurysm (PSA) between the left limb of an aortobifemoral Dacron graft and the common femoral artery (FA). The superficial FA (SFA) and deep FA (PFA) were exposed and controlled from an anterior thigh approach. Sheaths were inserted in each artery. An Amplatzer II vascular plug (Abbott, Abbott Park, IL) was deployed in the PFA. A Viabahn (Gore, Flagstaff, AZ) was first deployed in the left limb of the Dacron graft and into the proximal SFA. A Viabahn VBX stent (Gore, Flagstaff, AZ) was then deployed from inside the Viabahn and going proximally further into the limb of the bifurcated Dacron graft. The proximal end of the Viabahn VBX was flared with a larger balloon. The arteriotomies in the SFA and PFA were then used to create a side-to-side anastomosis. There were no immediate complications. On 6 months follow-up, the PSA sac was noted to have decreased in size, and the stents to be patent with no endoleak. Elective surgical repair of anastomotic PSAs is preferred since emergent repair has significantly higher morbidity and mortality. Still, open elective repair has its own mortality and limb loss risks in addition to postoperative wound infection, seroma, hematoma, and recurrence, along with myocardial infarction and stroke. The novel procedure we performed eliminated the risk factors of redo groin incision and added easier-to-control vessels in a clean field. With this procedure being performed more often in the future, these changes will hopefully prove to reduce complications while preserving flow in both the SFA and PFA.

Revascularisation des troncs supra-aortiques au cours de la maladie de Takayasu

Takayasu's disease is an inflammatory arteritis mainly affecting the aorta, its main divisional branches and pulmonary arteries. The arterial damage during Takayasu's disease is essentially occlusive and preferentially affects supra-aortic trunks. Indications for revascularization of supra-aortic trunks are clear but results are rarely reported. The purpose of this study was to evaluate the results of supra-aortic trunk revascularization in Takayasu's arteritis. We report a retrospective study conducted between 2012 and 2018 about patients with Takayasu's arteritis who underwent revascularization of supra-aortic trunks. Our series consisted of six patients. All patients were female. The average age was 29 (range 18-48) years. The operative indication was cerebrovascular ischemic symptoms in five patients and intermittent claudication of the upper limb in one. We performed aorto-bi-carotid bypass in four patients, a subclavian artery angioplasty in one and a vertebral artery angioplasty in one. At 1 month, operative mortality was zero and morbidity was marked by hemorrhagic stroke in one patient operated by conventional surgery. The average follow-up was 4 years (1.8). During the follow-up, one patient was reoperated after 18 months for an anastomotic false aneurysm in the ascending aorta. We noted a favorable outcome with total resolution of the symptomatology for the other patients and Doppler ultrasound confirmed patency during follow-up. Surgical revascularization of supra-aortic trunks in Takayasu's arteritis can be associated with a risk of stroke and a risk of anastomotic pseudoaneurysms. Endovascular revascularization appears to be less invasive but its long-term results are rarely reported.

POSTOPERATIVE ULTRASOUND MONITORING SURVEY IN PATIENTS WITH ABDOMINAL AORTIC ANEURYSMS

The diagnosis of early and late postoperative complication after abdominal aortic aneurysm surgery has a bearing on treatment results. Ultrasound duplex scanning must have been effective and accessible for postoperative monitoring, but such studies are inconsiderable in number. The aim is a definition of distinctive ultrasound criteria of postoperative complication and development of monitoring survey protocol. In this study authors analyzed results of assessment in 273 patients after open or endovascular repair in duration up to 102 months. All of the patients were underwent ultrasound duplex scanning including contrast-enhanced studies. All of specific revealed in 27,1% cases complications were divided to early and rate. The postoperative hemorrhage was most frequent (6,2%) among the others such as anastomotic thrombosis and graft infection. Stenotic lesions (8,1%), true and false anastomotic aneurysms (7,7%) were as late complications. The proposed protocol of diagnosis and monitoring conduced a timely detection of complications. In authors’ opinion, ultrasound duplex scanning is noninvasive, cost-effective and valid for postoperative monitoring survey.

Prise en charge chirurgicale des maladies inflammatoires de l’aorte

Non-infectious aortitis are usually due to giant cell arteritis (temporal arteritis), Takayasu and Behçet's diseases. Aortitis should be suspected in the presence of aortic wall thickening or of aneurysm or occlusion of the aorta and its branches in the absence of characteristic cardiovascular risk factors. Surgery is required in case of severe damage. But the quiescence of the inflammatory disease must be obtained before endovascular or surgical treatment to prevent complications such as anastomotic false aneurysm or stent thrombosis, especially common in this disease. The frequency of aortic aneurysms (in particular of ascending aorta) in giant cell arteritis encourages its systematic screening, as well as regular monitoring of the entire aorta during the follow-up. Behçet's and Takayasu diseases require the greatest control of inflammation and the knowledge of some surgical tricks to avoid the risk of recurrence. The literature review shows that endovascular treatment could reduce perioperative morbidity but did not allow reducing long-term complications.

門脈合併切除再建を伴う膵頭十二指腸切除術後に出現した吻合部門脈瘤に対しステント留置が有効であった1例

門脈合併切除再建を伴う膵頭十二指腸切除術後に出現した吻合部門脈瘤に対しステント留置が有効であった1例

Disease-specific guidelines for reporting adverse events for peripheral vascular medical devices

Disease-specific guidelines for reporting adverse events for peripheral vascular medical devices

Less Invasive (Common) Femoral Artery Aneurysm Repair Using Endografts and Limited Dissection

We report our experience with the treatment of femoral artery aneurysms (FAAs) under local anaesthesia with limited dissection, using endografts to facilitate the proximal anastomosis and some distal anastomoses. Between January 2006 and December 2010, six males, mean age 72 years (range, 65-80 years) with FAAs were treated at the University Hospital of Zurich. All operations were performed under local anaesthesia with analgosedation, except for one performed under spinal anaesthesia. After limited dissection and puncture of the anterior wall of the FAA, a sheath and a self-expanding endograft were introduced over a guide wire and with fluoroscopy they were guided intraluminally into the proximal normal neck of the FAA and deployed. Proximal arterial control was achieved with a balloon catheter introduced through the endograft. Then the FAAs were opened and distal arterial control is obtained with balloon catheters. The distal end of the stent graft was then sutured to the normal-sized distal arteries or to stent grafts placed within them. Of the six FAAs, four were true and two were false anastomotic aneurysms. Mean FAA diameter was 5.0 cm (range, 3.0-6.5 cm). Four patients also had aneurysmal involvement of the external iliac artery, one patient also had deep femoral aneurysms, but deep femoral circulation was always preserved. In three of the patients, the distal anastomosis was created to the femoral artery bifurcation, in two patients to the deep femoral artery when the superficial femoral artery (SFA) was chronically occluded and in one patient to the SFA. Immediate technical success was achieved in all six patients, and graft patency was observed from 9 to 48 months (mean 29 months). There were no amputations, complications or deaths. This technique for repair of FAAs can be performed under local anaesthesia, minimises dissection and complications and simplifies exclusion of these lesions. It is of particular value in high-risk patients with large FAAs.

Endovascular treatment of thoracic aortic diseases

Endovascular treatment of thoracic aortic diseases is an adequate alternative to open surgery. This method was firstly performed in Serbia in 2004, while routine usage started in 2007. Aim of this study was to analyse initial experience in endovacular treatment of thoracic aortic diseses of three main vascular hospitals in Belgrade - Clinic for Vascular and Endovascular Surgery of the Clinical Center of Serbia, Clinic for Vascular Surgery of the Military Medical Academy, and Clinic for Vascular Surgery of the Institute for Cardiovascular Diseases "Dedinje". Between March 2004. and November 2010. 41 patients were treated in these three hospitals due to different diseases of the thoracic aorta. A total of 21 patients had degenerative atherosclerotic aneurysm, 6 patients had penetrating aortic ulcer, 6 had posttraumatic aneurysm, 4 patients had ruptured thoracic aortic aneurysm, 1 had false anastomotic aneurysm after open repair, and 3 patients had dissected thoracic aneurysm of the thoracoabdominal aorta. In 15 cases the endovascular procedure was performed as a part of the hybrid procedure, after carotid-subclavian bypass in 4 patients and subclavian artery transposition in 1 patient due to the short aneurysmatic neck; in 2 patients iliac conduit was used due to hypoplastic or stenotic iliac artery; in 5 patients previous reconstruction of abdominal aorta was performed; in 1 patient complete debranching of the aortic arch, and in 2 patients visceral abdominal debranching were performed. The intrahospital mortality rate (30 days) was 7.26% (3 patients with ruptured thoracic aneurysms died). Endoleak type II in the first control exam was revealed in 3 patients (7.26%). The patients were followed up in a period of 1-72 months, on average 29 months. The most devastating complication during a followup period was aortoesofageal fistula in 1 patient a year after the treatment of posttraumatic aneurysm. Conversion was performed with explantation of stent-graft and open aortic in situ recontruction, followed by esophagectomy and the creation of cervical and gastrical stoma. Having in mind initial results of the 3 main vascular clinics in Belgrade, Serbia, economical situation in our country, as well as the published international results, endovascular treatment of thoracic aortic diseases is indicated in hemodinamicaly unstable patients with acute traumatic aneurysm, or in stabile patients older than 65, as well as in case of chronic diseases of the thoracic aorta in patients with significant comorbid conditions or in patients older than 65 years. Endovascular procedures on the thoracic aorta could be performed, hower, only in high-volume centers with experience in routine open surgery of thoracic aorta.

Midterm Results of Replacement of Synthetic Graft and Arterial Infection in the Groin With Femoropopliteal Vein

Infection of synthetic grafts or femoral arteries in the groin is a challenging problem to treat. Femoropopliteal vein (FPV) is an ideal conduit, but extensive replacement of infected aortic grafts with FPV has been associated with significant morbidity. The aim of this study was to evaluate early and long-term outcome of limited replacement with FPV of infected femoral arteries/grafts in the groin. Data from 37 patients who underwent excision of infected femoral grafts and replacement with FPV over an 18-year period from 1994 to 2012 were retrospectively analyzed. Surgical intervention was performed in 41 limbs of 27 men and 10 women (mean age, 67.5 years) at a median of 2.5 years after the original synthetic implantation (aortofemoral n = 21, femorofemoral n = 3, femorodistal n = 5, patch angioplasty n = 2) or, on average, 22.2 days after cardiac catheterization (n = 6) and one mycotic aneurysm. Presentation included draining sinus (n = 7), abscess (n = 4), persistent fevers (n = 6), and pseudoaneurysm (n = 10; intact, 4; ruptured, 6). Twenty-five patients (61%) underwent muscle flap cover of the FPV reconstruction. In-hospital/30-day mortality was 5.4% (2 of 37); one from respiratory failure 20 days postoperatively, and the second, a 93-year-old woman, after withdrawal of care at 24 hours. No patients required fasciotomy, and five wound hematomas required reoperation. Focal femoropopliteal vein thrombosis occurred in five limbs. Over a mean follow-up of 2.5 years (range, 0.03-13.3) 11 patients died of unrelated causes at a mean of 3.7 years (range, 0.2-10.6 years). Graft reintervention was required in seven patients during follow-up for graft thromboses (n = 2) stenoses (n = 2), and anastomotic false aneurysms (n = 3). Apart from the latter, there was no other suggestion of graft reinfection in any patient. Major limb loss occurred in one patient at 6 months despite a patent graft. Long-term FPV harvest morbidity included mild leg swelling in 10 patients. Replacement of infected synthetic grafts/femoral arteries in the groin with FPV is safe and results in excellent limb preservation and freedom from reinfection. FPV should be considered the preferred conduit in good-risk patients with infection limited to the groin.

Treatment of a Recurrent False Aneurysm of the Femoral Artery by Stent–Graft Placement From the Brachial Artery

An anastomotic false aneurysm is a well known complication after femoral artery surgery. Open surgical repair is the treatment of choice for anastomotic femoral aneurysms, but this can be challenging, unsuccessful, or even impossible. Endovascular repair is an alternative in these cases, but the delivery of a stent--graft in the femoral artery can be difficult. We report the case of a patient with a recurrent left femoral artery anastomotic false aneurysm, treated twice by open exclusion, and finally excluded successfully by a stent--graft that was inserted through the left brachial artery.

Open versus endovascular repair for patients with acute traumatic rupture of the thoracic aorta

The study objective was to compare the outcome between open and endovascular repair of acute traumatic rupture of the thoracic aorta. Seventy-five patients (mean age 38.6 ± 10.7 years) with an acute traumatic aortic rupture were referred to the Arnaud de Villeneuve Hospital between January 1990 and January 2010. Between January 1990 and December 2000, 35 patients (33 men, mean age 35.8 ± 11.3 years) underwent surgical repair using cardiopulmonary bypass. From January 2001, an endovascular approach was deliberately chosen; 40 patients (30 male, mean age 41 ± 10.1 years) underwent endovascular repair. The 2 groups were statistically comparable. The overall mortality rates for the surgical and endovascular groups were 11.4% (intraoperative mortality: 8.5%) and 2.5% (intraoperative mortality: 0%), respectively. The mortality rates related to aortic repair for the surgical and endovascular groups were 11.4% and 0%, respectively. In the surgical group, the morbidity rate was 14.2%: 4 cases of recurrent nerve palsy and 1 case of false anastomotic aneurysm were diagnosed at 52 months. In the endovascular group, the morbidity rate was 20%: 3 cases of intraoperative inadvertent coverage of supra-aortic trunks (requiring a secondary procedure in 2 cases after 1 and 2 years to revascularize the supra-aortic trunks), 1 proximal type I endoleak (requiring deployment of a second stent-graft at day 2), 2 stent-graft collapses in the first postoperative month (treated by open repair and explantation in 1 case and by the deployment of a second stent-graft in 1 case), 1 vertebrobasilar insufficiency after left subclavian artery coverage, and 1 intraoperative iliac rupture (surgically repaired). No cases of paraplegia or stroke were observed. The median follow-up was 7.7 (range, 0.4-15) years. Compared with open repair, endovascular repair of traumatic thoracic aortic rupture is associated with a lower death rate but failed to reach statistical significance, most likely because of underpowering. These results prompt us to consider endovascular repair as the first-line therapy for acute traumatic rupture of the thoracic aorta, except in some rare but challenging anatomic situations. New stent-graft designs, sizes, and deployment systems could improve the results of endovascular repair in these indications.

Aortic Transection and Diverting Bypass as Treatment of Repetitive Recurrent Abdominal Aortic False Aneurysm Rupture in a Patient With Behcet’s Disease

Abdominal aortic false aneurysms in patients with Behcet's disease have been reported frequently and repaired successfully by various procedures; however, anastomotic false aneurysms have often been reported to occur after the operation. In this article, we report a case of four-time repetitive, recurrent suprarenal abdominal aortic false aneurysm ruptures that lasted for 7 years. The location of this aneurysm was not easy to repair not only by open surgical procedures but by endovascular stent because the aortic defect was too close to the visceral arterial branches. The last operation consisted of primary repair of aortic defect, transection of abdominal aorta at the level of supraceliac aorta with end closure, and a thoracic aorta to abdominal aorta bypass with Dacron graft. An 8-year follow-up revealed no more abdominal aortic aneurysm recurrence.

A Safe Option to Perform an Apparent Difficult Redo Surgery

A 50-year-old female operated of Bentall five years before was referred to our hospital for an aneurysm of both right subclavian artery and brachiocephalic trunk associated with a false anastomotic aneurysm on the insertion of the left coronary artery. The procedure was performed under moderate hypothermic circulatory arrest; the false aneurysm was repaired, the brachiocephalic trunk and the subclavian aneurysm were resected, an aorto-carotid and axillary bypass were finally performed. The postoperative course was uneventful. She was discharged to home on postoperative day 7. At six-month follow-up, she was still asymptomatic.

Incidence and Determinants of Spinal Cord Ischaemia in Stent-graft Repair of the Thoracic Aorta

Objectives: Endovascular repair of descending thoracic aortic lesions is associated with a substantial risk of perioperative spinal cord ischaemia (SCI) which may lead to permanent paraplegia. We performed a retrospective analysis of our experience in the endovascular treatment of descending thoracic aortic lesions to define the incidence of SCI and to identify factors that contributed to its development. Methods: 67 consecutive patients underwent stent graft repair for descending thoracic aortic lesions including degenerative aneurysm (n = 19), type B dissection (acute n = 2, chronic n = 15), traumatic rupture (acute n = 14, chronic n = 4), penetrating aortic ulcer (n = 5), anastomotic false aneurysm (n = 4), mycotic aneurysm (n = 3) and embolic aortic lesion (n = 1) between June 2000 and June 2005. All procedures were performed with the patient under general anaesthesia and strict blood pressure monitoring. No patient had intra-operative monitoring of spinal evoked potential or cerebrospinal fluid (CSF) drainage to prevent SCI. Neurological evaluation was realized after recovery from general anaesthesia. Fifteen factors, including nature of aortic disease, length of aortic coverage, number of stent-grafts, coverage of the distal third of the thoracic aorta and subclavian artery coverage, were investigated as possible predictors of postoperative SCI. Results: Five patients (7.5%) had postoperative neurological deficits (immediate n = 2, delayed n = 3) referable to SCI. Univariate analysis showed that length of aortic coverage (p < 0.001) and number of stent-grafts deployed (p = 0.02) were significant predictors of SCI. Multivariate logistic regression analysis showed that length of aortic coverage was the only independent significant predictor of SCI. ROC curve analysis revealed 205 mm of aortic length coverage as the threshold for increased risk of postoperative SCI (p = 0.001), with specificity and sensitivity of 95.2 and 80% respectively. Conclusion: In our study, length of aortic coverage is the only independent predictive factor of SCI after endovascular treatment with 205 mm as a threshold for increased risk. Hence, methods to prevent SCI, especially those aimed at restoration of an adequate spinal cord perfusion pressure, should be offered to patients requiring extensive coverage of the descending thoracic aorta.