Endovascular treatment of thoracic aortic aneurysms: Results of the phase II multicenter trial of the GORE TAG thoracic endoprosthesis

Stent-graft treatment of thoracoabdominal aortic aneurysms after complete visceral debranching

Complex thoracoabdominal aortic aneurysm repair remains a difficult problem from both open and endoluminal approaches. The reduced morbidity and mortality rates reported to be associated with aortic stent-graft procedures makes this option more attractive, but it is hampered by the need for adequate proximal and distal seal zones. While branched and fenestrated aortic stent-grafts are being refined, an alternative is a two-stage surgical and endoluminal approach that is particularly useful for aneurysms involving the aortic visceral segment. The present report describes stent-graft repair in two patients after complete visceral artery revascularization or "debranching."

Endoleaks after endovascular repair of thoracic aortic aneurysms

OBJECTIVE

Endoleaks are one of the unique complications seen after endovascular repair of thoracic aortic aneurysms (TEVAR). This investigation was performed to evaluate the incidence and determinants of endoleaks, as well as the outcomes of secondary interventions in patients with endoleaks, after TEVAR.

METHODS

Over a 6-year period, 105 patients underwent TEVAR in the context of pivotal Food and Drug Administration trials with the Medtronic Talent (n = 64) and Gore TAG (n = 41) devices. The medical and radiology records of these patients were reviewed for this retrospective study. Of these, 69 patients (30 women and 39 men) had follow-up longer than 1 month and were used for this analysis. The patients were evaluated for the presence of an endoleak, endoleak type, aneurysm expansion, and endoleak intervention.

RESULTS

The mean follow-up in this patient cohort was 17.3 +/- 14.7 months (range, 3-71 months). Endoleaks were detected in 29% (20/69) of patients, of which 40% (8/20) were type I, 35% (7/20) were type II, 20% (4/20) were type III, and 5% (1/20) had more than one type of endoleak. Patients without endoleaks experienced greater aneurysm sac regression than those with endoleaks (-2.89 +/- 9.1 mm vs -0.13 +/- 7.2 mm), although this difference was not statistically significant (P = .232). All but 2 endoleaks (90%; 18/20) were detected on the initial postoperative computed tomographic scan at 30 days. Two endoleaks (10%; 2/20) developed late. The endoleak group had more extensive aneurysms with significantly larger aneurysms at the time of intervention (69.4 +/- 10.5 mm vs 60.6 +/- 11.0 mm; P = .003). Factors predictive of endoleak included male sex (P = .016), larger aneurysm size (P = .003), the length of aorta treated by stent grafts (P = .0004), and an increasing number of stents used (P < .0001). No open conversions were performed for treatment of endoleaks. Four (50%) of the eight type I endoleaks were successfully repaired by using endovascular techniques. None of the type II endoleaks was treated by secondary intervention. During follow-up, the maximum aneurysm diameter in the type II endoleak patients increased a mean of 2.94 +/- 7.2 mm (range, -4.4 to 17 mm). Spontaneous thrombosis has occurred in 29% (2/7) of the type II endoleaks. Patients with type III endoleaks experienced a decrease in mean maximal aneurysm diameter of 0.78 +/- 3.1 mm during follow-up.

CONCLUSIONS

Endoleaks are not uncommon after TEVAR. Many type I endoleaks may be treated successfully by endovascular means. Short-term follow-up suggests that observational management of type II endoleaks is associated with continued sac expansion, and these patients should be monitored closely.

Hybrid approach to complex thoracic aortic aneurysms in high-risk patients: surgical challenges and clinical outcomes

BACKGROUND

Endovascular therapy is a less invasive alternative treatment for high-risk patients with thoracic aortic aneurysms. However, this technology alone is often not applicable to complex aneurysmal morphology. The purpose of this study was to evaluate the utility of hybrid strategies in high-risk patients who are otherwise unsuitable for endovascular therapy alone.

METHODS

During an 18-month period, 31 high-risk patients (mean age, 69 years; range, 52-89 years) underwent combined open and endovascular approaches for complex aneurysms, including 16 patients with ascending and arch aneurysms and 15 patients with aneurysms involving visceral vessels. Among them, 11 patients had histories of aneurysm repairs. To overcome the anatomic limitations of endovascular repairs, various adjunctive surgical maneuvers were used, including aortic arch reconstruction in 3 patients, supra-aortic trunk debranching in 13 patients (including 8 patients who required aortas as inflow sources), and visceral vessel bypasses in 15 patients (including 10 patients who required bypasses to all 3 visceral branches). Additionally, carotid artery access was obtained in 1 patient, and iliac artery conduits were created in 12 patients.

RESULTS

Technical success was achieved in all patients. There was one perioperative death (3.2%) due to postoperative bleeding. Two patients (6.4%) had immediate type II endoleaks, which were resolved by the 1-month follow-up. Other procedure-related complications occurred in three patients (9.6%), including renal bypass thromboses in two patients and retroperitoneal hematoma, which was successfully managed conservatively, in one patient. During a mean follow-up of 16 months, two patients died of unrelated causes, whereas the remainder of patients were asymptomatic, without aneurysm enlargement.

CONCLUSIONS

Our study highlights how hybrid strategies incorporating surgical and endovascular approaches can be used successfully in treating patients with complex thoracic aortic aneurysms. This combined approach potentially expands the field of endovascular stent grafting and is an attractive solution for patients with poor cardiopulmonary reserves.

Contemporary results of open surgical repair of descending thoracic aortic aneurysms

Considerable progress has been made in the refinement of operative strategies to repair descending thoracic aortic aneurysms (TAA). While no single strategy has totally eliminated the postoperative morbidities of renovisceral and spinal cord ischemic complications, contemporary reports from centers of excellence detail admirable rates of overall risk in the 5-10% range. Balancing these risks represents a clinical dilemma for the aortic surgeon and a thoughtful, logical risk analysis of the individual patient presentation is clearly warranted before TAA repair. In this article, we review surgical approaches to TAA and adjunctive methods, examine the reports from centers of excellence, and elucidate the challenges yet to be overcome in the management of patients with aneurysms of the descending thoracic aorta.

Combined Staged Procedures for the Treatment of Thoracoabdominal Aneurysms

PURPOSE

To examine the efficacy of a staged approach for the treatment of thoracoabdominal aneurysms, with open visceral revascularization followed by aortic endografting, in selected patients not considered candidates for conventional surgical repair.

METHODS

A retrospective review was conducted of 13 consecutive patients (8 women; mean age 64 years, range 33-77) who underwent visceral bypass followed by endovascular thoracoabdominal stent-graft implantation since 1999. Three patients presented with symptomatic aneurysms and 2 with rupture. Two patients had connective tissue disorders. All patients were deemed unfit for conventional thoracoabdominal repair due to comorbid conditions. The procedures were tailored to the pathology and specific patient anatomical situation: 5 aortic dissections with aneurysmal degeneration and 8 aneurysms (5 Crawford type II, 2 type III, and 1 type IV).

RESULTS

The patients underwent retrograde visceral bypass (11 iliovisceral and 2 infrarenal aortic to visceral artery) followed by endovascular aortic relining with Zenith TX2 devices (n=7), homemade endografts (n=5), or a Talent thoracic endograft (n=1). Six patients required either a proximal or distal direct aortic repair (2 infrarenal reconstructions, 3 arch elephant trunk grafts, and 1 ascending aortic repair), while 3 patients also underwent left carotid-subclavian bypass grafting. Two patients developed paraplegia (1 following a ruptured aneurysm), and 2 patients had transient paraparetic events. Two patients had acute renal failure requiring short-term dialysis. Three patients died within 30 days; 2 late aneurysm-related deaths were noted. Three patients developed endoleaks during follow-up. Mean lengths of stay were 13 days (7-30) for the visceral bypass and 12 (3-25) for the endovascular stent-graft. In addition, remaining procedures in 8 patients required a mean of 7 days (0-14) in hospital.

CONCLUSION

Staged endovascular and open procedures are feasible for thoracoabdominal aneurysms in patients at prohibitive risk for open thoracoabdominal reconstruction. However, this approach still carries a significant risk of perioperative mortality and morbidity. The potential for less invasive alternatives should be investigated.

Results of endovascular repair of the thoracic aorta with the Talent Thoracic stent graft: The Talent Thoracic Retrospective Registry

BACKGROUND

Endovascular treatment of thoracic aortic diseases demonstrated low perioperative morbidity and mortality when compared with conventional open repair. Long-term effectiveness of this minimally invasive technique remains to be proven. The Talent Thoracic Retrospective Registry was designed to evaluate the impact of this therapy on patients treated in 7 major European referral centers over an 8-year period.

METHODS

Data from 457 consecutive patients (113 emergency and 344 elective cases) who underwent endovascular thoracic aortic repair with the Medtronic Talent Thoracic stent graft (Medtronic/AVE, Santa Rosa, Calif) were collected. Follow-up analysis (24 +/- 19.4 months, range 1-85.1 months) was based on clinical and imaging findings, including all adverse events. To ensure consistency of data interpretation and event reporting, one physician reviewed all adverse events and deaths for the whole cohort of patients. In the case of discrepancies, the treating physicians were queried.

FINDINGS

Among 422 patients who survived the interventional procedure (in-hospital mortality 5%, 23 patients), mortality during follow-up was 8.5% (36 patients), and in 11 of them the death was related to the aortic disease. Persistent endoleak was reported at imaging follow-up in 64 cases: 44 were primary (9.6%) and 21 occurred during follow-up (4.9%). Seven patients with persistent endoleak had aortic rupture during follow-up, at a variable time from 40 days to 35 months, and all subsequently died. A minor incidence of migration of the stent graft (7 cases), graft fabric alteration (2 cases), and modular disconnection (3 cases) was observed at imaging. Kaplan-Meier overall survival estimate at 1 year was 90.97%, at 3 years was 85.36%, and at 5 years was 77.49%. At the same intervals, freedom from a second procedure (either open conversion or endovascular) was 92.45%, 81.3%, and 70.0%, respectively.

CONCLUSION

Endovascular treatment for thoracic aortic disease with the Talent stent graft is associated with low early morbidity and mortality rates also for patients who are at high risk and treated on an emergency basis. Follow-up data indicate a substantial durability of the procedure with a high freedom from related death and secondary interventions.

Resection of the Descending Thoracic Aorta: Outcomes After Use of Hypothermic Circulatory Arrest

BACKGROUND

Use of hypothermic circulatory arrest (HCA) for operations on the descending thoracic aorta is controversial. While deep hypothermia may provide better end-organ and spinal cord function, prolonged cardiopulmonary bypass and circulatory arrest may increase morbidity. This study assessed outcomes after use of HCA for descending thoracic aortic resection in a large cohort of consecutive patients.

METHODS

Hypothermic circulatory arrest was utilized if arch or extensive descending thoracic aortic resection was required, or if aortic pathology precluded cross-clamping. One hundred thirty-two patients (mean age, 61.3 years) were identified. Diagnosis included fusiform (41.2%) or saccular aneurysm (10.7%) and acute (4.6%) or chronic (38.9%) dissection. Twenty-one patients presented with rupture. Arch resection (distal arch 100, total arch 11) was required in 111 patients (84.1%). The extent of descending thoracic aortic resection (required in 94%) included proximal third in 41 patients, proximal two-thirds in 6, and complete thoracic aorta in 77. The proximal anastomosis was performed with total body HCA while the distal anastomosis was constructed with lower body HCA only (duration upper body HCA 33.7 +/- 8.0 minutes; total duration lower body HCA 71.3 +/- 24.2 minutes).

RESULTS

Thirty-day mortality was 6.0%. Neurologic events included stroke (6.8%) and permanent lower extremity paralysis-paresis (4.5%). Temporary dialysis was needed in 7 (5.3%), though only 2 patients required permanent dialysis (1.9%). Independent predictors of a composite endpoint of death, stroke, permanent paralysis, or dialysis included duration of lower body HCA (p = 0.03) and major postoperative infection (p = 0.003).

CONCLUSIONS

Adjunctive use of deep hypothermic circulatory arrest for descending thoracic aortic resection affords excellent preservation of end-organ and spinal cord function with acceptable rates of mortality and significant morbidity.

Dynamic cine-CT angiography for the evaluation of the thoracic aorta; insight in dynamic changes with implications for thoracic endograft treatment

OBJECTIVE

Thoracic aneurysm preoperative imaging is performed using static techniques without consideration of normal aortic dynamics. Improved understanding of the native aortic environment into which thoracic endografts are placed may aid in device selection. It is unclear what comprises normal thoracic aortic pulsatility. We studied these phenomena dynamically using ECG-gated 64-slice CTA.

METHODS

Maximum diameter and area change per cardiac cycle was measured at surgically relevant anatomic thoracic landmarks in ten patients; 1.0 cm proximal and distal to the subclavian artery, 3.0 cm distal to the subclavian artery, and 3.0 cm proximal to the celiac trunk. Data was acquired using a novel ECG-gated dynamic 64-slice CT scanner during a single breath hold with a standard radiation dose and contrast load. Eight gated data sets, covering the cardiac cycle were reconstructed, perpendicular to the central lumen.

RESULTS

There is impressive change in both maximum diameter and area in the thoracic aorta during the cardiac cycle. Mean maximum diameter changes of greater than 10% are observed in the typical sealing zones of commercially available endografts corresponding to diameter increases of up to 5mm. Aortic area increases by over 5% per cardiac cycle.

CONCLUSIONS

ECG-gated dynamic CTA with standard radiation dose is feasible on a 64-slice scanner and provides insight into (patho) physiology of thoracic aortic conformational changes. Clinicians typically oversize thoracic endografts by 10%. With aortic pulsatility resulting in diameter changes of up to 17.8%, the potential exists for endograft undersizing, graft migration, intermittent type I endoleak, and poor patient outcome. Furthermore, aortic pulsatility is not evenly distributed, and non-circular stentgraft designs should be considered in the future since aortic distension in the aneurysm neck is not evenly distributed.

Totally laparoscopic assisted thoracic aorta endograft delivery by direct sheath placement into the aorta

This report describes the treatment of a descending thoracic aortic aneurysm with an endograft introduced through the infrarenal aorta by using the laparoscopic technique. The indication for infrarenal aorta access was the existence of heavy calcifications and stenosis of the both iliac arteries. We report what we think to be the first totally laparoscopic assisted thoracic aorta endograft delivery by direct sheath placement into the aorta.

An evaluation of centerline of flow measurement techniques to assess migration after thoracic endovascular aneurysm repair

OBJECTIVE

To validate a means by which migration of thoracic stent grafts can be reliably detected and quantified.

METHODS

Patients treated for thoracic aneurysms (without dissections) with either the Cook Zenith TX1/TX2 or the Gore TAG device were retrospectively reviewed. Patients with digital imaging data at a baseline study (discharge or 1-month computed tomographic scan) and a minimum of 6 months' follow-up were evaluated on a three-dimensional workstation. Centerline of flow (CLF) calculations were used to determine length measurements to establish distances from native vascular landmarks (left common carotid artery, left common carotid artery, and celiac artery) to the proximal and distal aspects of the fixation systems of stent grafts. Patients with evidence of fixation system migration (>10 mm of movement) or increasing thoracic aortic lengths (left common carotid artery to celiac artery distance) were subjected to more detailed reviews.

RESULTS

Of 194 patients evaluated (133 Zenith and 61 TAG), 46 were treated for dissections and excluded. Fifty-seven patients did not have a digital baseline study and available DICOM data for follow-up imaging at 6 months or later or had died before such follow-up imaging. The remaining 91 patients underwent assessment for device migration. Analyses were conducted on 19 patients at 6 months, on 42 at 12 months, on 12 at 24 months, on 13 at 36 months, and on 5 at 48 months. CLF analysis noted more than 10 mm of caudal movement of the proximal device in 10 patients and cranial movement of the distal device in 3 patients. When this subset was further scrutinized with regard to morphologic changes remote from the prosthesis and in the context of the overall aortic repair (such as elephant trunk grafts), only four patients had movement of the proximal or distal fixation system with respect to the initially deployed location. Two-dimensional axial image analysis identified migration in only one of the four patients with CLF-detected fixation system movement.

CONCLUSIONS

The importance of early migration detection cannot be overstated given the potential to avert consequences as evidenced by analyses of counterpart abdominal aortic aneurysm devices. In vivo thoracic device analysis is more complex than that for devices used for infrarenal aneurysms. Distance calculations based on CLF measurements may overestimate the frequency of true migration, yet they serve as a reasonable initial screening tool. The resultant subset of patients then must undergo a more detailed evaluation of device position in the context of the aortic morphology to differentiate true migration from devices that maintain stable fixation system positions.

Future of Endograft Surveillance

Frequent and sustained surveillance continues to be mandated for all patients who undergo endovascular repair of the aneurysmal aorta in order to minimize the small but attendant risk of aneurysm rupture. The primary motivation for surveillance includes evaluation of residual aneurysm sac size and presence of endoleak, as well as potential adverse device specific events, such as endograft migration, module disconnection, or component fatigue and failure. The current standard of care and future surveillance modalities after endovascular repair of both abdominal aortic and thoracic aortic aneurysms will be reviewed.

Immediate endovascular treatment of blunt aortic injury: our therapeutic strategy

BACKGROUND

Posttraumatic aortic rupture is a potentially lethal injury. Endovascular procedure has recently proved to be a valid option. Timing of the treatment, however, is still a debated issue. We evaluated the feasibility and safety of immediate stent-graft repair of acute posttraumatic aortic injury.

METHODS

From 1998 to 2005, 15 patients (11 men and 4 women, mean age 42.3 years) with blunt aortic injury were treated with immediate stent-graft positioning. In patients with clinical and radiologic signs of impending rupture, endovascular treatment was performed in an emergency setting (11 cases). In the 4 remaining patients the aortic lesion was treated after clinical management. When present, immediate life-threatening nonaortic lesions were treated before endovascular stenting (6 cases). In 1 case emergency laparotomy and endovascular procedure were performed simultaneously. Stent positioning was monitored by intraoperative transesophageal echocardiography in all cases.

RESULTS

Endovascular procedure was successful in 100% of the patients. Two patients died perioperatively as a consequence of a multiorgan failure. Both patients were in American Society of Anesthetists class V and were in severe intractable hemorrhagic shock before the procedure. Computed tomography scan performed before discharge showed correct positioning of the stent graft and absence of endoleaks in all cases. At a mean follow-up of 29 months (range 1-79) all patients were alive but 1, who died of unrelated cause, and no intervention-related complication had occurred.

CONCLUSIONS

Immediate stent-graft repair of posttraumatic aortic injury is a feasible and safe procedure. It allows us to minimize the surgical risks and to treat stable and unstable lesions even when associated lesions would contraindicate traditional surgical intervention.

Endovascular Repair of Thoracic Aortic Lesions Using Infrarenal Devices: Lessons Learned and Continued Applications

The application of endovascular devices for the treatment of a variety of thoracic aortic lesions has flourished worldwide over the past decade. Until physicians become facile with recently approved thoracic devices and these devices are immediately available even in emergency situations, the use of endovascular abdominal components offers physicians more options in managing thoracic lesions. We evaluated the safety, efficacy, and outcomes of commercially available, infrarenal endovascular graft components for managing lesions of the thoracic aorta. Nineteen patients were treated outside of a clinical trial using commercially available endovascular devices. The indications for treatment included acute traumatic lesions (n = 7), symptomatic ulcers (n = 4), focal aneurysms or pseudoaneurysms (n = 7), and symptomatic type B dissection (n = 1). The endovascular components included Excluder Aortic Cuffs (n = 9), AneuRx Aortic Cuffs (n = 5), Zenith Aortic Cuffs (n = 2), Zenith Aortic Tube Grafts (n = 2), and graft combinations (n = 1). Seventeen patients (89%) underwent successful endovascular treatment of their thoracic lesion. One patient required elective surgical conversion, and a second patient had a dissection that was not completely sealed endovascularly. There was no periprocedural mortality, and the major complication rate was 16% (3/19). Two patients had asymptomatic troponin leaks, and one patient developed an iliac rupture at the device introduction site, hypotension, and paraplegia. At a mean follow-up of 12.3 months, all successfully treated patients continue to have complete exclusion of the treated lesion. Infrarenal endovascular graft components can be very useful in the treatment of selected patients with amenable thoracic lesions until thoracic devices are available in all necessary sizes, readily accessible to treating physicians, and cost-effective.

Endovascular repair of a proximal aortic arch aneurysm: A novel approach of supra-aortic debranching with antegrade endograft deployment via an anterior thoracotomy approach

Although open surgical repair continues to be the standard therapy for thoracic aortic aneurysms, endovascular intervention has evolved into an acceptable strategy for patients who have prohibitive risks for conventional surgical treatments. Aortic arch aneurysm, in particular, is associated with substantial surgery-related morbidities, yet is typically not suitable for endovascular intervention. We describe a combined technique of supra-aortic trunk debranching through an anterior thoracotomy followed by endovascular repair of a large proximal arch aneurysm in an 82 year-old man 8 years after an ascending aortic aneurysm repair.

Midterm Outcome in 158 Consecutive Gore TAG Thoracic Endoprostheses: Single Center Experience

BACKGROUND

Despite recent improvements in surgical technique, some patients with descending thoracic aortic pathologies are unable to undergo open surgical repair due to significant comorbidities and/or unfavorable thoracic aortic anatomy. Some of these patients might be able to tolerate a less invasive approach, such as endoluminal grafting. We reviewed our consecutive clinical experience with the Gore TAG endoprosthesis (W. L. Gore & Assoc, Flagstaff, AZ) for the endovascular exclusion of assorted descending thoracic aortic pathologies in higher surgical risk patients.

METHODS

After obtaining institutional review board approval, 158 high surgical risk patients underwent attempted delivery of a Gore TAG thoracic endoprosthesis between February 2000 and July 2004. Indications for study enrollment were atherosclerotic aneurysm (n = 76), aortic dissection (n = 36), penetrating aortic ulcer (n = 15), contained rupture (n = 11), pseudoaneurysm (n = 10), traumatic aortic injury (n = 5), aortobronchial fistula (n = 4), and aortic coarctation (n = 1).

RESULTS

The device was successfully delivered in 156 (98.7%) patients. Mean patient age was 72 +/- 12.1 years. Three (1.9%) patients developed transient paraparesis after graft deployment and 1 (0.6%) patient developed paraplegia. While postimplantation endoleaks were observed in 18 (11.5%) patients, only 12 patients required reintervention. Thirty-day mortality was 3.8% (6 of 156). Mean follow-up was 21.5 +/- 18.8 months, and the overall mortality was 17.3% (27 of 156).

CONCLUSIONS

Endoluminal grafting of multiple types of descending thoracic aorta pathologies with the Gore TAG thoracic endoprosthesis is feasible and safe in higher surgical risk patients. Additional studies and long-term follow-up of these patients are warranted.

Early outcomes after elective and emergent endovascular repair of the thoracic aorta

BACKGROUND

Endovascular treatment of thoracic aortic pathology has emerged as a viable alternative to open surgical repair in both the elective and emergent settings. The aim of this study was to evaluate preoperative work-up, intra-operative strategy, and outcomes of endovascular stent-grafting of the thoracic aorta in patients undergoing elective repair and those undergoing emergent repair.

METHODS

All patient information was obtained by a retrospective review of an established clinical database for all endovascular thoracic stent-graft cases. From October 1999 to August 2005, 70 patients were treated with endovascular stent-grafts for lesions of the thoracic aorta. Thirty-five patients had an elective endovascular procedure, and 35 patients had an emergent procedure.

RESULTS

Thirty-five patients in the endovascular (EL) group were treated for aneurysm (n = 34) and type B dissection (n = 1). Thirty-five patients in the emergent (EM) group were treated for aneurysm (n = 10), intramural hematoma (n = 10), type B dissection (n = 7), traumatic rupture (n = 7), and aortoesophageal fistula (n = 1). Preoperative angiography was performed in 94.3% (33/35) of EL patients but in only 45.7% (16/35) EM patients (P < .005). The EM procedures had significantly shorter operative times, used lower contrast volumes, used fewer stent-graft components (mode 2, range 1 to 5 vs mode 1, range 1 to 3; P = .02), and spinal cerebrospinal fluid drains were used significantly less often (82.9% vs 57.1%, P = .04). Both groups had similar 30-day morbidity, mortality (0/35 EL vs 1/35 [2.9%] EM, P = .99), postoperative endoleak (9/35 [25.7%] EL vs 7/35 [20.0%] EM, P = .78), endovascular failure (3/35 [8.6%] EL vs 5/35 [14.3%] EM, P = .71), and patient survival.

CONCLUSION

There are significant differences in the underlying pathology, preoperative evaluation, and operative course between elective and emergency treatment endovascular procedures for lesions of the thoracic aorta. Endovascular repair of thoracic aortic lesions can be accomplished with low perioperative mortality and morbidity rates, as well as acceptable endoleak and endovascular failure rates for both elective and emergency procedures.

Robotic Replacement of the Descending Thoracic Aorta: An Alternative to Endovascular Therapy?

Background

Replacement of the descending thoracic aorta is traditionally performed via a left thoracotomy. Endovascular treatment of descending thoracic aortic aneurysms has recently evolved as an alternative treatment for selected patients, yet no long-term results are available. The authors replaced the descending thoracic aorta in a group of pigs with an interposition Dacron graft using a closed-chest, totally robotic technique.

Methods

Ten pigs, weighing 25 to 45 kg, underwent surgery using the DaVinci robotic surgical system. Under single-lung ventilation and CO2 insufflation, the descending thoracic aorta was completely mobilized. Proximal and distal cross-clamps were applied through separate accessory stab wounds. The mid-descending thoracic aorta was excised. An interposition Dacron graft was robotically sewn in an end-to-end fashion to the descending thoracic aorta using interrupted nitinol clips.

Results

All animals survived the procedure. Mean aortic clamp time was 55 ± 14 minutes. All anastomoses were completed without difficulty with a mean total anastomotic time of 42 ± 11 minutes. The anastomoses were challenged for bleeding by administrating α1-adrenergic receptor agonists to a systolic blood pressure of 200 mm Hg with no evidence of leak.

Discussion

Robotic replacement of the thoracic aorta is feasible and reproducible. This procedure provides the standard Dacron graft repair with its known long-term results. The added value of robotic technology to the therapeutic armamentarium in the treatment of thoracic aortic aneurysms may be worth the effort required for procedural development. Furthermore, it may serve as a valid alternative to endovascular treatment of thoracic aortic aneurysms.

Utility of left subclavian artery revascularization in association with endoluminal repair of acute and chronic thoracic aortic pathology

BACKGROUND

A rapidly increasing number of thoracic aortic lesions are now treated by endoluminal exclusion by using stent grafts. Many of these lesions abut the great vessels and limit the length of the proximal landing zone. Various methods have been used to address this issue. We report our experience with subclavian artery revascularization in association with endoluminal repair of acute and chronic thoracic aortic pathology.

METHODS

Thirty (43%) of 70 patients undergoing thoracic endovascular stent-graft placement from January 2001 to August 2005 had lesions adjacent to or involving the origin of the subclavian artery. The mean age was 62 years (range, 22-85 years; 63% were men, and 37% were women). This subgroup of 30 patients had indications for repair that included thoracic aortic aneurysm (n = 15), traumatic transection (n = 6), chronic dissection with pseudoaneurysm (n = 5), and acute dissection with intramural hematoma (n = 4). All 30 patients had the subclavian origin covered by the stent graft. In eight cases (27%), no effort was made to revascularize the subclavian artery before or during the endograft placement procedure. Twenty-three (77%) of 30 patients underwent subclavian to carotid artery transposition (n = 21) or bypass (n = 2) before (n = 12; average of 14 days before stent-graft placement), concomitant with (n = 10), or after (n = 1) the endovascular procedure. Physical examination and computed tomography scans were performed after surgery at 1, 6, and 12 months and annually thereafter. The mean follow-up was 18 months (range, 1-51 months).

RESULTS

Five acute complications occurred in the eight patients (63%) who had the subclavian artery covered without pre-endograft revascularization and included four patients who experienced stroke (accounting for the only death) and one patient who developed symptomatic subclavian-vertebral steal that necessitated transposition 7 months later. Two (9%) of the 23 patients who had subclavian revascularization experienced left-sided vocal cord palsies, and 1 patient (4%) developed lower extremity paraparesis secondary to spinal cord ischemia. No late endoleaks related to retrograde sac perfusion from the most distal great vessel have been identified in any patient.

CONCLUSIONS

Subclavian revascularization procedures can be performed with relatively low risk. Complications are rare, and patient recovery is rapid. Although this is not necessary in all cases, we advocate subclavian to carotid transposition when the aortic lesion is within 15 mm of the left subclavian orifice to prevent type II endoleak or perfusion of a dissected false lumen when the ipsilateral vertebral artery is patent and dominant or when coronary revascularization using an ipsilateral internal mammary artery is anticipated and in cases that necessitate extensive coverage of intercostals that contribute to spinal cord perfusion. Carotid to subclavian artery bypass should be reserved for patients with a patent internal mammary artery conduit perfusing a coronary vessel and should be combined with proximal subclavian ligation.

The COOK TX2 Thoracic Stent Graft: Preliminary Experience and Trial Design

Endovascular treatment of thoracic aortic pathology (ETAP) has been under development for over a decade. Only recently has one device been approved in the United States for treatment of descending thoracic aortic aneurysms. The length of this development process is due to multiple device and deployment system modifications, as understanding has evolved of the unique challenges of reconstruction in the thoracic aorta. The TX2 system has evolved from pioneering custom-made designs into a mature system with several features designed to improve early and late results. Controlled trials are necessary to compare the outcomes of ETAP with standard open repair. This article will detail the current generation of the device, review large published single-center experiences, and describe an ongoing prospective, nonrandomized, multi-institutional, investigational device exemption (IDE) phase II pivotal clinical trial investigating the safety and effectiveness of this device in elective treatment of patients with descending thoracic aortic aneurysms.

Endovascular Therapy of Thoracic Aneurysms: Gore TAG Trial Results

Although many thoracic endografts are commercially available in Europe, only three such devices have been introduced to the United States. Gore TAG endoprosthesis was the first to enter clinical trials in the United States for treatment of descending thoracic aortic aneurysm, and gained the approval of the US Food and Drug Administration for general use in March 2005. Through clinical trials, the safety and efficacy of the Gore TAG endoprosthesis were proven and shown to be superior to those of open surgical repair. This article details the device and results of these trials.

Endovascular Thoracic Aortic Repair and Previous or Concomitant Abdominal Aortic Repair: Is the Increased Risk of Spinal Cord Ischemia Real?

Spinal cord ischemia after endovascular thoracic aortic repair remains a significant risk. Previous or concomitant abdominal aortic repair may increase this risk. This investigation reviews the occurrence of spinal cord ischemia after endovascular repair of the descending thoracic aorta in patients with previous or concomitant abdominal aortic repair. Over an 8-year period, 125 patients underwent endovascular exclusion of the thoracic aorta at the Mount Sinai Medical Center. Twenty-eight of these patients had previous or concomitant abdominal aortic repair. The 27 patients who underwent staged repairs all had cerebrospinal fluid (CSF) drainage during and following repair. This population was analyzed for the complication of spinal cord ischemia and factors related to its occurrence. Mean follow-up was 19.3 months (range 1-61). Spinal cord ischemia developed in four of the 28 patients (14.3%) who underwent endovascular thoracic aortic repair with previous or concomitant abdominal aortic repair, while one of 97 patients (1.0%) developed ischemia among the remaining thoracic endograft population. One patient with concomitant abdominal aortic repair developed cord ischemia that manifested 12 hr following the procedure. The remaining three patients with previous abdominal aortic repair developed more delayed-onset paralysis ranging from the third postoperative day to 7 weeks following repair. Irreversible cord ischemia occurred in three patients, with full recovery in one patient. Major complications from CSF drainage occurred in one patient (3.7%). Spinal cord ischemia occurred at a markedly higher rate in patients with previous or concomitant abdominal aortic repair. This risk continued beyond the immediate postoperative period. The benefit of perioperative and salvage CSF drainage remains to be determined.

Thoracic Endografts: Procedural Steps, Technical Pitfalls and How to Avoid Them

Recent US Food and Drug Administration (FDA) approval of a thoracic endograft has created explosive interest among physicians to learn to use this minimally invasive technology. The level of interest is similar to the period more than a decade ago, following FDA approval of infrarenal abdominal endografts, which initiated the "endo" revolution among vascular specialists. Many physicians view the descending thoracic aorta as a simple, straight tube and, thus, technically less challenging than endografts for infrarenal abdominal aortic aneurysm. However, the thoracic aorta presents certain unique features that make this a challenging procedure. Technical challenges posed by the thoracic aorta have resulted in a significant time-lag (since release of abdominal aortic aneurysm endografts), testing the ability of engineers and physicians to devise and complete trials successful enough for FDA approval of thoracic endografts. This article addresses the various procedural steps and tips on avoiding pitfalls.

Endovascular repair of proximal endograft collapse after treatment for thoracic aortic disease

We report two cases of proximal endograft collapse with an almost complete aortic occlusion after endovascular tube-graft treatment of thoracic aortic disease (thoracic aneurysm after a type B dissection, traumatic blunt aortic rupture) using the TAG Gore system. Oversizing of endografts is known to cause this complication. In our two cases, however, the oversizing was between 12% and 21.7%, which is less than the allowed oversizing of 25% that is recommended by the manufacturer. This endograft-related complication might be due to a poor alignment of the currently available endografts in highly angulated and tight aortic arches. In the first case, a combined endovascular and open emergent repair procedure achieved a reopening of the proximal endograft by proximal extension (TAG Gore). In the second case, proximal extension was not considered owing to a precise positioning of the endograft distal to the left carotid artery. A balloon-expanding Palmaz stent was therefore placed interventionally in the proximal part of the TAG graft to expand the endograft and to avoid another collapse of the device. This proximal endograft collapse has to be acknowledged as a potentially hazardous complication. We therefore recommend that the proximal part of thoracic endografts in the aortic arch should be closely monitored and we offer two possible endovascular solutions for resolving the problem of proximal endograft collapse.

Endograft exclusion of acute and chronic descending thoracic aortic dissections

OBJECTIVES

To analyze the results of endograft exclusion of acute and chronic descending thoracic aortic dissections (Stanford type B) with the AneuRx (n = 5) and Talent (n = 37) thoracic devices and to compare postoperative outcomes of endograft placement acutely (<2 weeks) and for chronic interventions.

METHODS

Patients treated for acute or chronic thoracic aortic dissections (Stanford type B) with endografts were included in this study. All patients (n = 42) were enrolled in investigational device exemption protocols from August 1999 to March 2005. Three-dimensional computed tomography reconstructions were analyzed for quantitative volume regression of the false lumen and changes in the true lumen over time (complete >95%, partial >30%).

RESULTS

Forty-two patients, all of whom had American Society of Anesthesiologists (ASA) risk stratification > or =III and 71% with ASA > or = IV, were treated for Stanford type B dissections (acute = 25, chronic = 17), with 42 primary and 18 secondary procedures. All proximal entry sites were identified intraoperatively by intravascular ultrasound (IVUS). The procedural stroke rate was 6.7% (4/60), with three posterior circulation strokes. Procedural mortality was 6.7% (4/60). The left subclavian artery was occluded in 11 patients (26%) with no complaints of arm ischemia, but there was an association with posterior circulation strokes (2/11) (18%). No postoperative paraplegia was observed after primary or secondary intervention. Complete thrombosis of the false lumen at the level of endograft coverage occurred in 25 (61%) of 41 patients < or =1 month and 15 (88%) of 17 patients at 12 months. Volume regression of the false lumen was 66.4% (acute) and 91.9% (chronic) at 6 months. Lack of true lumen volume (contrast) increase and increasing false lumen volume (contrast) suggests continued false lumen pressurization and the need for secondary reintervention. Thirteen patients (31%) required 18 secondary interventions for proximal endoleaks in 6, junctional leaks in 3, continued perfusion of the false lumen from distal re-entry sites in 3, and surgical conversion in 4 for retrograde dissection.

CONCLUSIONS

Preliminary experience with endografts to treat acute and chronic dissections is associated with a reduced risk of paraplegia and lower mortality compared with open surgical treatment, the results of medical treatment alone, or a combination.

Aortic neck morphology after endovascular repair of descending thoracic aortic aneurysms

BACKGROUND

Endovascular repair has emerged as a less-invasive treatment for descending thoracic aortic (DTA) aneurysms. However, the durability of this procedure relies on the stability of proximal and distal fixation sites. This study analyzes 3 years of computed tomography (CT) data on aortic neck morphology after endovascular DTA aneurysm repair.

METHODS

Between 1999 and 2001, 139 patients underwent successful endovascular DTA repair as part of a prospective, multicenter clinical trial investigating the Gore TAG thoracic endoprosthesis. Contrast-enhanced, high-resolution CT scans were obtained at 1 (baseline), 12, 24, and 36 months and submitted to an independent core laboratory for image analysis. The aorta was carefully measured by using computerized planimetry and a standardized protocol. Neck diameter was measured at 10-mm intervals for 2 cm above and below the aneurysm and correlated with graft migration and endoleak.

RESULTS

The mean proximal neck diameter increased from a baseline of 30.2 +/- 4.6 mm to 32.0 +/- 4.3 mm at 36 months (P <.05), and the annual diameter increase was 0.8, 0.4, and 0.6 mm at 12, 24, and 36 months. The mean distal neck diameter increased from 29.4 +/- 3.8 mm to 32.1 +/- 5.0 mm at 36 months (P <.05), and the annual diameter increase was 1.1, 0.4, and 1.2 mm at 12, 24, and 36 months. At 36 months, freedom from neck dilation of > or =5 mm was 87%, and freedom from migration of > or =10 mm was 83%. An endoleak was present in 11 (9%) of 122 patients at baseline, 7 (7%) of 96 at 12 months, 6 (9%) of 68 at 24 months, and 1 (3%) of 33 at 36 months. Neck dilation was not associated with graft migration or endoleak.

CONCLUSIONS

Three years after endovascular repair of DTA aneurysms, there is progressive enlargement of the proximal and distal aortic necks. Although uncommon for patients to develop significant neck dilation, when it does occur, it is not associated with graft migration or endoleak. Continued surveillance of aortic neck morphology after descending thoracic aneurysm endografting is recommended.

Distal Embolus Protection With an Intra-Aortic Filter During Stent-Graft Repair of a Severely Atherosclerotic Thoracic Aortic Aneurysm

PURPOSE

To assess the technical feasibility and efficacy of distal embolus protection with an intra-aortic filter during stent-graft repair in a patient diagnosed with a shaggy aorta.

TECHNIQUE

In a 75-year-old man with a severely atherosclerotic thoracic aortic aneurysm, stent-graft repair was combined with transposition of the arch branches to the ascending aorta under thoracotomy. A filtration-type embolus protection device with a nitinol basket and polyester fabric was introduced through a 12-F sheath and opened in the supraceliac aorta during the stent-graft procedure; it was safely pulled back into the sheath after the stent-grafts were implanted. The stent-graft repair was successful, and abundant atheromatous debris was captured in the filter. Neither procedure-related embolic events nor neurological deficits were observed.

CONCLUSIONS

Use of the intra-aortic filter device to prevent distal embolism during thoracic stent-graft repairs may be feasible and efficacious in severely atherosclerotic patients.

Hybrid Approaches to Thoracic Aortic Aneurysms

Background— Thoracic aortic aneurysm affecting the arch and proximal descending thoracic aorta requires 2-stage repairs that include proximal elephant trunk graft placement and completion of thoracic or thoracoabdominal repair. The application of endovascular grafting to complete the proximal procedure avoids a thoracotomy and may improve the morbidity and mortality of the patient population at risk.

Methods and Results— A retrospective review of 399 thoracic endovascular grafts at our institution between 2000 and 2004 identified 22 patients who required elephant trunk and endovascular completion. Three patients underwent mesenteric bypass in addition to their proximal repairs. Mean follow-up was 10 months (range 1 to 42 months); there were no ruptures, and all patients returned for follow-up. Technical success was achieved in all patients. The 1-, 12-, and 24-month mortality rates (by Kaplan-Meier analysis) were 4.5%, 15.8%, and 15.8%, respectively. Caudal migration of the endograft occurred in 1 patient, and all but 2 aneurysms decreased or remained stable in size. The 2 patients with growth included a type III endoleak (which resolved after treatment) and pressurization through an expanded PTFE stentgraft. Three cases of transient paraparesis occurred (all in patients requiring mesenteric bypass or abdominal aortic aneurysm repair), and there were no paraplegias or strokes.

Conclusions— Endovascular completion of elephant trunks is feasible and can be accomplished with minimal mortality. Meticulous imaging follow-up is required to detect persistent aneurysm pressurization and to verify the integrity of the repair. Improvements in implant design and delivery systems will further simplify the second-stage portion of these complex aneurysm repairs.

Stacked Proximal Aortic Cuffs:An “Off-the-Shelf” Solution for Treating Focal Thoracic Aortic Pathology

PURPOSE

To report our early experience with the endovascular placement of stacked Zenith main body extensions (cuffs) in the treatment of focal thoracic aortic pathology in high-risk patients.

METHODS

Between January 2003 and May 2004, 6 patients (3 men; mean age 59 years, range 37-82) with focal aortic pathology underwent endovascular repair using stacked 30 and 32-mm-diameter Zenith main body extensions. The setting was a university tertiary referral center for vascular disease. Indication for treatment included 2 descending thoracic aneurysms and individual cases of traumatic thoracic tear, diverticulum of Kommerell, thoracic pseudoaneurysm, and aortoesophageal fistula.

RESULTS

All procedures were performed successfully, with a mean of 3 cuffs used. The patient with an aortoesophageal fistula expired after successful cuff placement due to sequela of massive pretreatment hemorrhage; fistula coverage was confirmed at autopsy. There were no type I endoleaks. Morbidity included an occluded right subclavian artery from traumatic passage of the device through the artery. No left subclavian arteries were covered. No neurological deficits or paraplegia was observed. The cuffs were patent in all surviving patients at an average follow-up of 7 months (range 3-12). Computed tomography in all survivors confirmed adequate cuff placement, absence of endoleak, and lack of cuff migration. Based on this experience, the following technical recommendations are offered: (1) right subclavian cutdown when needed to reach a lesion beyond the range of the sheath, (2) Dacron chimney placement, (3) stiff guidewire usage, (4) wire placement from the right subclavian artery through the common femoral artery if necessary to ease a sharp bend in the arch, and (5) cuff overlap of 25% to 50%.

CONCLUSIONS

In high-risk patients, focal aortic pathology can be successfully treated with off-the-shelf commercially available cuffs using a stacking technique with acceptable mortality, morbidity, and short-term durability.

Great Vessel Transposition for Antegrade Delivery of the TAG Endoprosthesis in the Proximal Aortic Arch

PURPOSE

To report a technique for antegrade delivery of the TAG stent-graft during repair of lesions in the proximal aortic arch.

TECHNIQUE

Via an 8-cm median sternotomy, a bifurcated graft, usually 14 or 16 mm in diameter, is anastomosed to the ascending aorta with 4-0 Prolene suture; a 10-mm straight graft is cut obliquely and anastomosed to the heel of the bifurcated graft for delivery of the endograft antegrade across the aortic arch. The great vessels in turn are clamped, transected at the arch, and sutured to the bypass graft. A 9-F sheath is secured in the conduit, and a 250-cm angled hydrophilic guidewire is passed to the desired iliac artery and exteriorized through the femoral sheath. The conduit is clamped, and the TAG's delivery sheath is substituted for the 9-F sheath. A marker is placed on the conduit to assure that the stent-graft is deployed just beyond the limb origins of the bifurcated graft. The conduit is introduced across the aortic arch, followed by the endograft, which is positioned at the marker as the sheath is withdrawn into the conduit. After completion angiography, the delivery sheath is removed, and the conduit is transected and oversewn. Heparinization is reversed, and the incision is closed, with one mediastinal drainage tube in place.

CONCLUSIONS

This technique allows precise delivery of the endoluminal graft at the proximal aortic arch, thus avoiding problems with retrograde delivery.