Aortobronchial and aortoesophageal fistulae as risk factors in surgery of descending thoracic aortic aneurysms

Patch aortoplasty and anatomical lung resection in a patient with aortobronchial fistula due to aortic psuedo-aneurysm

Aortobronchial fistula (ABF) is a rare and devastating complication, if left untreated. Its main clinical manifestation is hemoptysis, and there are no defined guidelines for its treatment yet. Herein, we present the case of a 74-year-old male who complained of back pain and hemoptysis. The patient was diagnosed with pseudo-aneurysm and ABF, and he underwent hybrid thoracic endovascular aortic repair. However, hemoptysis recurred. With patch aortoplasty and anatomical lung resection, successful management of ABF was achieved, with no relapse for 5 years.

Surgical treatment for secondary aortoesophageal fistula

Background

Aortoesophageal fistula (AEF) is a relatively rare condition that is often life-threatening. Secondary AEF is a complication of previous surgery, which can be more critical and challenging than primary AEF. The number of secondary AEF is increasing due to increase in the number of thoracic endovascular aortic repair (TEVAR). Although TEVAR has become a successful alternative surgical strategy for thoracic aortic aneurysms, secondary AEF after TEVAR might be critical than other secondary AEF because of severe adhesion between the esophagus and residual thoracic aortic wall.

Methods

This study analyzed six patients with secondary AEF who were treated at Tokyo Medical University Hospital between 2011 and 2016. These participants included four patients who had undergone TEVAR and two who had undergone total arch replacement.

Results

Although they were subsequently hospitalized for a long period, open surgical repair was completed in two patients who had undergone total arch replacement. TEVAR alone was performed in two patients who had undergone TEVAR and they were discharged without major complications shortly. Combined repair of TEVAR as a bridge to open surgery was planned for two patients who had undergone TEVAR. However, reconstruction of the aorta and esophagus could not be completed in these patients due to severe adhesions, and they died during hospitalization.

Conclusions

Definitive open repair was successfully performed in patients with secondary AEF after total arch replacement. However, in the patients with secondary AEF after TEVAR, severe adhesion between the aorta and esophagus led to difficulty in performing a successful definitive open repair. The strategy for secondary AEF should, therefore, be decided considering the etiology of secondary AEF. In secondary AEF after TEVAR, definitive open repair is difficult to complete because of catastrophic complication, and palliative treatment using TEVAR without reconstruction of aorta and esophagus can be an alternative.

Effective strategy in the treatment of aortobronchial fistula with recurrent hemoptysis

Aortobronchial fistula (ABF) involves the formation of an abnormal connection between the thoracic aorta and the central airways or the pulmonary parenchyma and is associated with an increased risk of mortality. An ABF typically manifests clinically with symptoms of hemoptysis, and currently, there is a lack of defined guidelines for its treatment. Here, we report the cases of two patients who suffered from recurrent hemoptysis due to ABF with pseudoaneurysm. We propose that removal of the aorta with concomitant lung resection and coverage of the aorta using the pericardial membrane is a definite treatment to lower recurrence of ABF and persistent infection.

Endovascular Repair of Aortobronchial Fistula due to Saccular Aneurysm of Thoracic Aorta

Aortobronchial fistula (ABF) is a rare condition which can be lethal if left untreated. Open surgical treatment carries high morbidity and mortality. Recent advances in endovascular technology have made thoracic endovascular aortic repair (TEVAR) the treatment of choice. We present a successful endovascular repair of aortobronchial fistula due to a saccular aneurysm of descending thoracic aorta.

Aortobronchial and aortoenteric fistula

Pathologic communication between the thoracic aorta and esophagus or tracheobronchial tree is a rare vascular condition and most commonly develops after open or endovascular aortic repair complicated by infection. Patients with aortoesophageal or tracheobronchial fistula often present with systemic infection and are at risk for major hemorrhage. Medical management is uniformly fatal. Expeditious definitive management requires operative repair by open repair or a combination of endovascular and open procedures. Appropriate antibiotic regimens are important for preventing graft reinfection.

Management of aorto-esophageal fistula secondary after thoracic endovascular aortic repair: a review of literature

Aorto-esophageal fistula (AEF) is a rare and lethal entity, and the difficulty of making diagnosis of AEF is well-known. As promising results in the short-term effectiveness of thoracic endovascular aortic repair (TEVAR) promote its usage, the occurrence of AEF after TEVAR (post-TEVAR AEF) increases as one of the major complications. Therefore, we provide a review concerning the management strategy of post-TEVAR AEF. Although its representative symptom was reported as the triad of mid-thoracic pain and sentinel hematemesis followed by massive hematemesis, the symptom-free interval between sentinel hemorrhage and massive exsanguination is unpredictable. However, the physiological condition represents a surgical contraindication. Accordingly, early diagnosis is important, but either CT or esophago-gastro-duodenoscopy rarely depicts a typical image. The formation of post-TEVAR AEF might be associated with the infection of micro-organisms, which is uncontrollable with anti-biotic administration. The current first-line strategy is combination therapy as follows, (1) to control bleeding by TEVAR in the urgent phase, and (2) radical debridement and aortic/esophageal re-construction in the semi-urgent phase. In view of the high mortality and morbidity rate, it is proposed that the choice in treatment strategies might be affected by patient`s condition, size of the wall defects and the etiology of AEF. Practically, we should keep in mind the importance of making an early diagnosis and, once a suspicious symptom has occurred in a patient with a history of TEVAR, the existence of post-TEVAR AEF should be suspected. A prospective registry together with more developed technologies will be needed to establish a future strategy.

Endoluminal Stent-Graft Repair of Aortobronchial Fistulas: Bridging or Definitive Long-Term Solution?

Purpose:

To describe our experience with endoluminal stent-graft repair of aortobronchial fistulas (ABF) and to analyze midterm results focusing on late chronic graft infections, secondary conversion, and survival.

Methods:

The records of 8 patients (6 men; mean age 69 years, range 28–88) treated between March 1997 and October 2003 for traumatic and postsurgical ABFs were reviewed. Seven presented with hemoptysis and 1 with hemorrhagic shock. According to the severity of emergency, patients underwent computed tomography, angiography, bronchoscopy, and transesophageal echocardiography. Preoperatively, no clinical signs of infection were evident. Two different stent-graft models (Talent and Excluder) were implanted using standard endovascular techniques.

Results:

Procedural and clinical success was achieved in all patients. Paraplegia, secondary intervention, conversion, or procedure-related death was not observed. Mean follow-up was 30 months (range 0.6–77). One patient with a postsurgical ABF (Dacron tube graft) successfully treated with an Excluder stent-graft died 13 months later from hemorrhage secondary to aortoesophageal fistula repair procedures. A second patient died from pneumonia after 42 months. A third patient, in whom 2 Talent stent-grafts had been implanted to treat an ABF from the false lumen of a type B dissection, died 7 months later from massive hemorrhage.

Conclusions:

Endoluminal stent-grafting of ABF is feasible and the preferred method of treatment. Secondary conversion due to endograft infection is not absolutely mandatory, but close surveillance is necessary.

Two-stage Surgery for an Aortoesophageal Fistula Caused by Tuberculous Esophagitis

An aortoesophageal fistula (AEF) is an extremely rare, potentially fatal condition, and aortic surgery is usually performed together with extracorporeal circulation. However, this surgical method has a high rate of surgical complications and mortality. This report describes an AEF caused by tuberculous esophagitis that was treated successfully using a two-stage operation. A 52-yr-old man was admitted to the hospital with severe hematemesis and syncope. Based on the computed tomography and diagnostic endoscopic findings, he was diagnosed with an AEF and initially underwent thoracic endovascular aortic repair. Esophageal reconstruction was performed after controlling the mediastinal inflammation. The patient suffered postoperative anastomotic leakage, which was treated by an endoscopic procedure, and the patient was discharged without any further problems. The patient received 9 months of anti-tuberculosis treatment after he was diagnosed with histologically confirmed tuberculous esophagitis; subsequently, he was followed as an outpatient and has had no recurrence of the tuberculosis or any further issues.

Strategies for the treatment of aorto-oesophageal fistula

OBJECTIVES

Presenting a surgical strategy for aorto-oesophageal fistula (AEF).

METHODS

From October 1999 to August 2013, 16 patients with AEF were treated at Kobe University Hospital. The mean age was 65.5 ± 10.2 years, and the male/female ratio was 13/3. Eight patients had non-dissecting thoracic aneurysm, 3 had chronic aortic dissection, 5 had oesophageal cancer and 1 had fish bone penetration. Five patients were in shock. Four patients had previous thoracic endovascular aortic repair (TEVAR) in the descending aorta and 1 had hemi-arch replacement. As treatment for AEF, 8 patients underwent TEVAR, 2 had a bridge TEVAR to open surgery, 2 had extra-anatomical bypass (EAB) and 5 had in situ reconstruction of the descending aorta. The oesophagus was resected in 8 patients, and an omental flap was installed in 7 patients. For the 4 most recent cases, simultaneous resection of the aorta and oesophagus, in situ reconstruction of the descending aorta using rifampicin-soaked Dacron graft and omental flap installation were performed.

RESULTS

Hospital mortality was noted in 4 patients (25.0%; persistent sepsis n = 3 and pneumonia n = 1). However, since 2007, only 1 of 5 patients died (pneumonia). All patients with oesophageal cancer died during follow-up. Two patients underwent oesophageal reconstruction using a pedicled colon graft and one is on the waiting list for oesophageal reconstruction.

CONCLUSIONS

Bridging TEVAR is a useful adjunct in treating AEF patients with shock. One-stage surgery consisting of resection of the aneurysm and oesophagus, in situ reconstruction of the descending aorta and omental flap installation provided a better outcome in the AEF surgical strategy compared with conservative treatment.

Aortoesophageal fistula as a complication of thoracic aorta aneurism stent grafting - a case report and literature review

Background:

Endovascular stent grafting is performed in patients with aneurysms of aorta or other major vessels. The procedure is considered to be generally safe, with a low risk of complications, the most common of which include endoleaks, stenosis or thrombosis at the stagraft and itsmigration.

Very rare complications include aortoesophageal and aortobronchial fistulas (0.5–1.7% cases).

Case Report:

A 64-year-old patient was admitted to our hospital with suspected aortoesophageal fistula. Two years prior, the patient had undergone a stent graft repair of the thoracic aorta at the local vascular surgery clinic. Both laboratory results and CT angiography revealed aortoesophageal fistula, which was also detected in endoscopic examination.

Despite intensive treatment and preparation for surgery, the patient died 6 days after admission.

Conclusions:

Aortoesophageal and aortobronchial fistulas are among the most dangerous and difficult-to-treat complications in the treatment of thoracic aortic aneurysms by endovascular stent-grafting. This clearly indicates that preventive care and regular medical examinations are important to prevent their occurrence.

In situ replacement of the thoracic aorta using an equine pericardial roll graft for an aortobronchial fistula due to aortic rupture

A 74-year-old woman with massive hemoptysis and shock who had been diagnosed with thoracic aortic rupture underwent in situ replacement of the thoracic aorta using an equine pericardial roll graft. The lower lobe of the left lung was resected because of a massive hematoma and adhesion to the wall of the thoracic aorta. Intraoperative microscopic examination of the resected aortic wall revealed Gram-positive bacteria (alpha-streptococcus in bacterial cultivation). Histology of the resected aorta revealed abscess formation in the media and adventitia of the aortic wall associated with disruption of the media (dissection). Postoperative computed tomography revealed no fluid collection around the graft 1 month after surgery, and magnetic resonance imaging showed no significant graft dilation 20 months after operation. The equine pericardium can be an option of alternative graft materials for in situ replacement of the thoracic aorta in patients with an aortobronchial fistula due to aortic rupture.

Endoluminal graft therapy for the treatment of an aorto-bronchial fistula: mid-term follow-up

Open surgical repair of aorto bronchial fistulas is associated with a high morbidity and mortality. Endovascular stent graft as an alternative therapy, though limited, has produced acceptable initial results, but few reports of mid-term follow-up are available. We report the mid-term results with the use of an endograft to treat a patient with both an aorto bronchial fistula and a contained rupture of the thoracic aorta.

Successful treatment of an aortoesophageal fistula after emergency endovascular thoracic aortic stent-graft placement

We report the case of a 57-year-old man who underwent emergency stent-graft placement in August 2003 due to a contained rupture of a distal descending aortic aneurysm. After 1 month the patient was readmitted with chest pain as well as swallowing disorders. A computed tomographic scan revealed a fistula between the distal esophagus and the excluded aneurysm sac. The patient was treated by an esophagectomy, a cervical esophagostomy, as well as a feeding gastrostomy. The infectious parietal thrombus was partially debrided and the aneurysm sac was filled with vancomycin. After 3 months continuity was reinstalled with a pedicled isoperistaltic transverse colonic conduit. The patient recovered uneventfully. At a 3 month follow-up, he showed no signs of infection. However, he is still being treated with antibiotic therapy of ciprofloxacin for a minimum of 1 year.

[Aortobronchial fistulas]

INTRODUCTION

Aortobronchial fistulas are uncommon but generally fatal if not treated surgically. Haemoptysis is the main symptom of this pathology. STATES OF ART AND PERSPECTIVES: Aortobronchial fistulas occur most commonly in patients with thoracic aneurysms (atherosclerosis, mycotic, aortic surgery's complication...). Main investigation is CT angiography with 2 D and 3 D reconstructions.

CONCLUSION

Endovascular exclusion can be efficient treatment option.

Surgical treatment of five patients with aortobronchial fistula in the aortic arch

Aortobronchial fistula (ABF) is a rare condition that is almost always fatal in the absence of prompt and proper treatment. However, treatment remains challenging, particularly in the aortic arch. We present six operations for 5 such patients, in which no in-hospital deaths occurred. One patient with mycotic aneurysm died suddenly 10 months postoperatively. Another patient required reoperation 5-months after operation due to additional ABF. No pseudoaneurysms or graft-related complications were observed in the remaining patients. In patients with ABF, performance of operations as soon as possible after onset and minimal dissection of adherent lung tissue appear to improve outcomes.

Endografting of the thoracic aorta:

BACKGROUND

Thoracic aortic dissections, ruptures, fistulae, and aneurysms pose a unique surgical challenge. Traditional repair of thoracic aortic aneurysms involves thoracotomy with graft interposition. Despite advances in perioperative care and both total and partial cardiopulmonary bypass, conventional surgery carries a significant morbidity and mortality. Principal complications include bleeding, paraplegia, stroke, cardiac events, pulmonary insufficiency, and renal failure. Recent enthusiasm for innovative endovascular therapies to treat aortic disease has spurred many centers to investigate endoluminal grafting of the thoracic aorta. Early reports on endovascular repair using custom made "first generation devices" demonstrated the technique to be feasible with a mortality and morbidity comparable to open repair.

METHODS AND RESULTS

From February 2000 to February 2001, endovascular stent graft repair of the thoracic aorta was performed in 46 patients (mean age 70; 29 male and 17 female) using the Gore Excluder. Twenty-three patients (50%) had atherosclerotic aneurysms, fourteen patients (30%) had dissections, three patients (7%) had aortobronochial fistulas, three patients (7%) had pseudoaneurysms, two patients (4%) had traumatic ruptures, and one patient (2%) had a ruptured aortic ulcer. Patient characteristics, procedural variables, outcomes, and complications were recorded. All patients were followed with chest CT scans at 1, 3, 6, and 12 months. Mean follow up was 9 months ranging from 1 to 15 months. All procedures were technically successful. There were no conversions. Average duration of the procedure was 120 minutes. Average length of stay was 6 days, but most patients left the hospital within 4 days (64%) after endoluminal grafting. Overall morbidity was 23%. Two patients (4%) had endoleaks that required a second procedure for successful repair. Two patients (4%) died in the immediate postoperative period. There were no cases of paraplegia. At follow-up, one patient had an endoleak found the day after the procedure and another patient had an endoleak 6 moths post procedure. Both were treated successfully with additional stent grafts. There were no cases of migration. One patient died of a myocardial infarction 6 months after graft placement. The Gore Excluder device was voluntarily recalled on February 26, 2001. Therefore, from June 2000 to January 2001, 37 patients underwent endovascular stent graft repair of the thoracic aorta for various disease entities using our customized thoracic graft (Endomed). Twenty-seven patients (73%) had aneurysms, six (16%) had dissections, two (5%) had pseudoaneurysms, one (2%) had a traumatic transection, and one patient (2%) had an embolizing ulcer. Patients were followed with CT scans at 1, 3, 6, and 12 months. All procedures were technically successful. There were no conversions. The average age was 68 years.(17-87). And the male and female ratio was 24/13. One patient died in the operating room from iliac rupture and one died from embolization/stroke in the immediate postoperative period. Two patients died within 30 days from comorbid factors. The total 30-day mortality was 10%. Two patients had endoleaks. One returned to the operating room and needed an additional cuff. The other had a small leak in a proximal dissection that is being followed. There were no cases of paraplegia.

CONCLUSION

Thoracic endoluminal grafting is a safe and feasible alternative to open graft repair and can be performed successfully with good results. Early data suggest that an endoluminal approach to these disease entities maybe favorable to open resection and graft replacement. Technical details of Endoluminal stent grafting of the thoracic aorta for different disease entities have been discussed at length.

Aortoesophageal fistula: value of in situ aortic allograft replacement

PURPOSE

The purpose of this report is to describe our experience in management of aortoesophageal fistulas (AEF) with special emphasis on the value of in situ aortic allograft replacement.

PATIENTS

Nine patients presenting with AEF were observed between May 1988 and April 2002. There were 4 men and 5 women with a mean age of 54.3 years (range, 32-77 years). Six patients presented secondary AEF after aortic repair. Two patients presented primary AEF after rupture of an atherosclerotic aneurysm into the esophagus. In the remaining patient, AEF was caused by swallowing a fishbone. In 6 cases involving true AEF with a direct communication between the aorta and esophagus, massive exsanguinating hematemesis occurred. It was usually preceded by minor sentinel bleeding. Two patients presented esophagoparaprosthetic fistula (EPPF). One patient presented primary AEF that was contained by a large thrombus in the communication. The clinical picture in these 3 patients involved severe sepsis without hemorrhage.

RESULTS

Two patients died as a result of massive hemorrhage before assessment and surgical treatment could be undertaken. One 77-year-old woman presenting EPPF refused to undergo surgery and died because of infection. The remaining 6 patients underwent surgical treatment with various outcomes. One man died during thoracotomy caused by exsanguinating hemorrhage. One woman presenting EPPF was treated by exclusion followed by ascending aorta to abdominal aorta bypass grafting, removal of the prosthesis, esophageal exclusion, and directed esophageal fistula. She died of infection. The other 4 patients were treated by in situ aortic allograft replacement. The damaged esophagus was repaired by using the Thal technique in 1 patient. In the remaining 3 cases subtotal esophagectomy was performed in association with cervical esophagostomy, ligation of the abdominal esophagus, gastrostomy, and jejunostomy. One patient died of sepsis during the first 24 hours after the operation. The other 3 patients underwent secondary esophagoplasty and survived with no further sign of infection. Mean duration of follow-up in the survivor group was 53 months (range, 15-95 months). Overall 6 patients, including 3 that did not undergo surgical treatment, died and 3 patients survived.

CONCLUSION

Our experience confirms that AEF is a rare but catastrophic disorder. In situ allograft replacement usually in association with subtotal esophagectomy appears to be an excellent salvage modality whenever emergency surgery is feasible.

Endoluminal stent grafting of the thoracic aorta: initial experience with the Gore Excluder

PURPOSE

The purpose of this study was to describe our experience with endoluminal graft repair of a variety of thoracic aorta pathologies with a commercially developed device currently under investigation. Our patient population included patients eligible for open surgical repair and those with prohibitive surgical risk.

METHODS

From February 2000 to February 2001, endovascular stent-graft repair of the thoracic aorta was performed in 46 patients (mean age, 70 years; 29 male and 17 female patients) with the Gore Excluder. Twenty-three patients (50%) had atherosclerotic aneurysms, 14 patients (30%) had dissections, three patients (7%) had aortobronchial fistulas, three patients (7%) had pseudoaneurysms, two patients (4%) had traumatic ruptures, and one patient (2%) had a ruptured aortic ulcer. Patient characteristics, procedural variables, outcome, and complications were recorded. All patients were followed with chest computed tomographic scans at 1, 3, 6, and 12 months. Follow-up period ranged from 1 month to 15 months, with a mean of 8.5 months.

RESULTS

All the procedures were technically successful. There were no conversions. Average duration of the procedure was 120 minutes. Average length of stay was 6 days, but most patients (64%) left the hospital within 4 days after endoluminal grafting. The overall morbidity rate was 23%. Two patients (4%) had endoleaks that necessitated a second procedure for successful repair. Two patients (4%) died in the immediate postoperative period. There were no cases of paraplegia. At follow-up examination, one patient had an endoleak found the day after the procedure and another patient had an endoleak 6 months after the procedure. Both cases were treated successfully with additional stent-grafts. There were no cases of migration. One patient died of a myocardial infarction 6 months after graft placement. In patients treated for aneurysm (n = 23), the aneurysm diameter ranged from 5.0 to 9.5 cm (mean, 6.8 cm). Residual sac measurements were obtained at 1, 6, and 12 months, with mean sac reductions of 0.59 cm, 0.77 cm, and 0.85 cm, respectively. In three cases, the sac remained unchanged, without evidence of endoleak.

CONCLUSION

Thoracic endoluminal grafting with the Gore Excluder is a safe and feasible alternative to open graft repair and can be performed successfully with good results. Early data suggest an endoluminal approach to these disease entities may be favorable over classical resection and graft replacement.

Endoluminal stent graft repair of aortobronchial fistulas

OBJECTIVE

To describe our experience with endoluminal stent graft repair of aortobronchial fistulas.

METHODS

We reviewed the records of patients treated with endoluminal stent grafting of aortobronchial fistulas at a private teaching hospital. All patients underwent the following diagnostic studies: computed tomography, angiography, bronchoscopy, and transesophageal echocardiography. With standard endovascular techniques, two different devices were implanted.

RESULTS

Between March 1997 and October 2000, we treated four patients with postsurgical fistulas. The patients were diagnosed with hemoptysis between 3 and 23 years after aortic replacement grafting for thoracic aneurysms. Diagnostic studies varied in their ability to find the fistula. Transesophageal echocardiography most reliably demonstrated the fistula in the patients. All were successfully treated by exclusion with endoluminal stent grafting. The patients had no complications and no further episodes of hemoptysis.

CONCLUSION

Endoluminal stent grafting of aortobronchial fistulas is feasible and may become the preferred method of management in patients at high risk.

Surgical treatment for a ruptured thoracic aortic aneurysm

OBJECTIVE

The treatment for a ruptured thoracic aortic aneurysm remains controversial. This study was undertaken to assess the outcome from surgery.

METHODS

Between 1993 and 1998, we have performed 19 operations for a ruptured thoracic aortic aneurysm. Patients with an impending rupture or a chronic false aneurysm were excluded. There were 11 men and 8 women, with a mean age of 70.5 +/- 6.7 years. The aneurysm was caused by dissection in 8 patients. Of these, 7 were acute (Stanford type A, 6; type B, 1), and the other one was chronic (type B). Aortic rupture occurred into the pericardial cavity (n = 7), into the left lung (n = 6), the mediastinum (n = 3), the pleural cavity (n = 2), or into the esophagus (n = 1). Severely unstable hemodynamics were noted in 12 patients with a rupture into the pericardium, mediastinum, or pleural cavity (Group A). Inotropic support was required in each of these patients. Metabolic acidosis developed all but 1 patient. The 7 patients with a rupture into the lung or esophagus coughed or vomited blood (Group B). The operative approach was anterior (n = 17) or lateral (n = 2). Grafts were placed in the ascending aorta (n = 4), ascending and transverse arch aorta (n = 7), transverse arch aorta (n = 3), or in the descending thoracic aorta (n = 5). Selective cerebral perfusion was used in 13 patients.

RESULTS

There were 5 hospital deaths (26.3%). The postoperative complications included central nervous system dysfunction (n = 3), low cardiac output syndrome or cardiac arrhythmias (n = 3), respiratory failure (n = 4), acute renal failure (n = 1), and local or systemic infections (n = 4). The perioperative event-free rate was 36.8% overall, 25% in Group A, and 57.1% in Group B.

CONCLUSIONS

Patients with unstable hemodynamics require prompt operative intervention. Rupture into the esophagus is associated with a high mortality rate. Rupture in a thoracic aortic aneurysm can be successfully treated with emergency surgery.

Management of aortobronchial fistula with an aortic stent-graft

Aortobronchial fistula presenting as massive hemoptysis is a rapidly fatal process that is extremely difficult to manage. We report a case in which endovascular occlusion of a fistula between a thoracic aortic pseudoaneurysm and lung was successfully managed by placement of an aortic endovascular stent-graft. Stent-grafting is a promising technique in managing complications of thoracic aneurysms and grafts.