Thoracic aortic stent-graft devices: problems, failure modes, and applicability

Long-term outcomes of TEVAR for thoracic aortic diseases: a retrospective single-center study

BACKGROUND

The outcomes of Thoracic Endovascular Aortic Repair (TEVAR) vary depending on thoracic aortic pathologies, comorbidities. This study presents our comprehensive endovascular experience, focusing on exploring the outcome in long term follow-up.

METHODS

From 2006 to 2018, we conducted TEVAR on 97 patients presenting with various aortic pathologies. This retrospective cohort study was designed primarily to assess graft durability and secondarily to evaluate mortality causes, complications, reinterventions, and the impact of comorbidities on survival using Kaplan-Meier and Cox regression analyses.

RESULTS

The most common indication was thoracic aortic aneurysm (n = 52). Ten patients had aortic arch variations and anomalies, and the bovine arch was observed in eight patients. Endoleaks were the main complications encountered, and 10 of 15 endoleaks were type I endoleaks. There were 18 reinterventions; the most of which was TEVAR (n = 5). The overall mortality was 20 patients, with TEVAR-related causes accounting for 12 of these deaths, including intracranial bleeding in three patients. Multivariant Cox regression revealed chronic renal diseases (OR = 11.73; 95% CI: 2.04-67.2; p = 0.006), previous cardiac operation (OR = 14.26; 95% CI: 1.59-127.36; p = 0.01), and chronic obstructive pulmonary diseases (OR = 7.82; 95% CI: 1.43-42.78; p = 0.001) to be independent risk factors for 10-year survival. There was no significant difference in the survival curves of the various aortic pathologies. In the follow-up period, two non-symptomatic intragraft thromboses and one graft infection were found.

CONCLUSION

Comorbidities can increase the risk of TEVAR-related mortality without significantly impacting endoleak rates. TEVAR is effective for severe aortic pathologies, though long-term graft durability may be compromised by its thrombosis and infection.

Endovascular Repair in Blunt Thoracic Aortic Injury: A 10-Year Single Center Experience

BACKGROUND

Life-threatening blunt thoracic aortic injury (BTAI) typically occurs alongside multiple other traumatic injuries. Symptoms of BTAI can range from being asymptomatic in the case of intimal tears to becoming catastrophic in the case of uncontained aortic ruptures. The aim of this research was to examine the clinical outcomes for those who underwent thoracic endovascular aortic repair (TEVAR) in hospital settings.  Methods: A cross-sectional retrospective study was conducted using patient data that were extracted from Al-Noor Specialist Hospital, Makkah, Saudi Arabia, for the duration between January 2011 and December 2021. This study included data from all patients aged 18 and up who had been diagnosed with BTAI and had undergone TEVAR. The BTAI diagnoses were confirmed using CT scans. Logistic regression was utilized to identify predictors of patients' health status improvement and length of stay.

RESULTS

A total of 80 patients were involved. Around 50.0% (n=40) of the patients had grade 3 thoracic aortic injuries. The median duration of stay was 14.00 days (Interquartile range 21.00). Only one patient developed post-procedure complications (1.3%). Almost one-third (31.3%; n=25) of the patients required subclavian coverage. One patient developed intraoperative endoleak (1.3%). One patient developed an access site complication (1.3%). The mortality rate within 30 days of the operation was 1.3%. The vast majority of the patients (92.5%; n=74) showed improvement upon discharge from the hospital. The baseline patient characteristics and length of hospitalization had no effect on the improvement of patient status upon discharge or their length of stay (p>0.05).

CONCLUSION

Patients with BTAI have shown an excellent success rate with TEVAR and a low complication rate. Predictors of procedure success and length of stay need to be identified; however, this can't be done without larger-scale investigations. This can aid in the development of preventative measures that improve clinical outcomes for the patients.

Dynamic Changes in the Aorta During the Cardiac Cycle Analyzed by ECG-Gated Computed Tomography

Background

To characterize the difference in aortic dimensions during the cardiac cycle with electrocardiogram (ECG)-gated computed tomography angiography (CTA) and to determine whether other parameters in comparison to diameter could potentially provide a more accurate size reference for stent selection at the aortic arch and the proximal thoracic descending aorta.

Methods

The CTA imaging of 90 patients during the cardiac cycle was reviewed. Three anatomic locations were selected for analysis (level A: 1 cm proximal to the innominate artery; level B: 1 cm distal to the left common carotid artery; and level C: 1 cm distal to the left subclavian artery). We measured the maximum diameter, the minimum diameter, the lumen area, the lumen perimeter, and the diameter derived from the lumen area, and the changes of each parameter at each level during the cardiac cycle were compared.

Results

The mean age was 60.9 ± 12.4 years (range, 16–78 years). There was a significant difference in the aortic dimensions during the cardiac cycle (p < 0.001). The diameter derived from the lumen area at all three levels was changed least over time when compared to the area, perimeter, and the maximum aortic diameter (all p < 0.01).

Conclusion

The aortic dimensional differences during the cardiac cycle are significant. The aortic diameter derived from the lumen area over other parameters may provide a better evaluation for selecting the size of the stent at the aortic arch and the proximal thoracic descending aorta. A prospective study comparing these different measurement parameters regarding the outcomes is still needed to evaluate the clinical implications.

Patient-Specific Virtual Stent-Graft Deployment for Type B Aortic Dissection: A Pilot Study of the Impact of Stent-Graft Length

Thoracic endovascular aortic repair (TEVAR) has been accepted as a standard treatment option for complicated type B aortic dissection. Distal stent-graft-induced new entry (SINE) is recognised as one of the main post-TEVAR complications, which can lead to fatal prognosis. Previous retrospective cohort studies suggested that short stent-graft (SG) length (<165 mm) might correlate with increased risk of distal SINE. However, the influence of SG length on changes in local biomechanical conditions before and after TEVAR is unknown. In this paper, we aim to address this issue using a virtual SG deployment simulation model developed for application in type B aortic dissection. Our model incorporates detailed SG design and hyperelastic behaviour of the aortic wall. By making use of patient-specific geometry reconstructed from pre-TEVAR computed tomography angiography (CTA) scan, our model can predict post-TEVAR SG configuration and wall stress. Virtual SG deployment simulations were performed on a patient who underwent TEVAR with a short SG (158 mm in length), mimicking the actual clinical procedure. Further simulations were carried out on the same patient geometry but with different SG lengths (183 mm and 208 mm) in order to evaluate the effect of SG length on changes in local stress in the treated aorta. Comparisons of simulation results for different SG lengths showed the location of maximum stress varied with the SG length. With the short SG (deployed in the patient), the maximum von Mises stress of 238.9 kPa was found on the intimal flap at the distal landing zone where SINE was identified at 3-month follow-up. Increasing the SG length caused the maximum von Mises stress to move away from the distal landing zone where stress values were reduced by approximately 17% with the medium-length SG and by 60% with the long SG. This pilot study demonstrates the potential of using the virtual SG deployment model as a pre-surgical planning tool to help select the most appropriate SG length for individual patients.

Clinical Outcomes of the Seal® Thoracic Stent Graft for Traumatic Aortic Injury in a Korean Multicenter Retrospective Study

BACKGROUND

Thoracic endovascular aneurysm repair (TEVAR) has been used as a primary treatment for blunt traumatic aortic injury (TAI). However, the outcomes of midterm surveillance of Seal® stent-graft durability for TAI have not been extensively studied. Thus, we aimed to report the midterm outcomes of TEVAR using the Seal® stent graft for blunt TAI.

METHODS

Patients with blunt TAI treated with TEVAR using the Seal® thoracic stent graft between 2007 and 2013 in Korea were included. Midterm outcomes included technical/clinical success, in-hospital death, aorta/procedure/device-related adverse events, secondary procedures, and 30-day and all-cause mortality.

RESULTS

A total of 99 patients (54% men; mean age, 48 years) were included. Grade III or higher injuries were present in 95% of patients, including 15 free ruptures of the thoracic aorta, and 64% of injuries were located in zone III. The median procedure and hospitalization duration were 90 min and 11 days, respectively. The technical success rate was 98%. The number of in-hospital mortalities (n = 8) and stroke (n = 2) were observed at 30 days. Late stroke and paraplegia (>30 days) were not observed during the mean 49 ± 26 months of follow-up (median, 48 months; range, 0-117 months). There were no aorta-related mortalities or conversions to open repair. Secondary procedures were performed in 8 patients, all of which were carotid-subclavian bypasses for delayed left subclavian occlusion. The all-cause mortality rate was 5% at 30 days and 8% at 1 year. The survival rate was 95% at 30 days, 92% at 1 year, 92% at 3 years, and 89% at 5 years. One type Ia endoleak occurred at 18 months after the procedure.

CONCLUSIONS

TEVAR with the Seal® stent graft for TAI showed favorable midterm outcomes. The incidence of major adverse events after the procedure was low.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Contemporary Results of Endovascular Repair of Isolated Abdominal Aortic Dissection with Unibody Bifurcated Stent Grafts

OBJECTIVES

To report the midterm safety and efficacy of the Aegis™-B (Microport, Shanghai, China) unibody bifurcated stent graft for endovascular treatment of isolated abdominal aortic dissection (IAAD).

BACKGROUND

Isolated abdominal aorta dissection (IAAD) is a rare event. Endovascular stent grafts seem to offer an efficient therapeutic approach to treat IAAD. However, the relatively small diameter of the infrarenal aorta and aortic bifurcation remains the main anatomical limitation to endovascular repair.

METHODS

Between 2008 and 2015, we retrospectively evaluated 32 IAAD patients (21 men; mean age 58 ± 18 years), who underwent endovascular repair using Aegis™-B unibody bifurcated stent graft. Narrow proximal landing zone and narrow distal aorta was present in 11 (34.4%) patients and 10 (31.3%) patients, respectively. In the follow-up period, aortic remodeling was observed with computed tomography angiography.

RESULTS

All patients were treated by endovascular means, with a primary technical success rate of 100%. During a mean follow-up period of 30.71 ± 16.36 months (range, 8-56 months), no death, rupture, stent fracture, material failure, or device migration was observed. Complete false lumen thrombosis was observed in all patients at 1 year, and all patients were free from false lumen growth in the follow-up.

CONCLUSIONS

Endovascular treatment of IAAD using the Aegis™-B system appears to be safe and effective. Results from this study suggest this algorithm can provide stable, secure fixation for IAAD patients with narrow proximal landing zone, and distal aorta.

Restrictive bare stent prevents distal stent graft-induced new entry in endovascular repair of type B aortic dissection

OBJECTIVE

Distal stent graft-induced new entry (SINE) can occur after thoracic endovascular aortic repair (TEVAR) of type B aortic dissection. This study investigated the mechanism of distal SINE and its prevention using a restrictive bare stent (RBS) technique.

METHODS

From January 2013 to December 2014, 68 consecutive type B aortic dissection patients received endovascular repair at our center. The RBS technique was used with distal oversizing (between the diameter of the thoracic stent graft and the descending aorta true lumen diameter at the level of the intended distal edge of the thoracic stent graft) >20%.

RESULTS

Twenty-three patients received TEVAR with a single thoracic stent graft (TEVAR group, n = 23); the rest received TEVAR combined with the RBS technique (TEVAR + RBS group, n = 45). Four distal SINEs occurred in the TEVAR group. Distal oversizing (69.7% ± 35.5% vs 31.2% ± 24.5%; P = .005) and expansion mismatch ratio (132.2% ± 16.9% vs 106.5% ± 11.6%; P < .05) were significantly higher in the SINE patients. Compared with standard TEVAR, TEVAR + RBS was associated with significantly lower distal oversizing (TEVAR vs TEVAR + RBS group, 59.8% ± 24.7% vs 16.7% ± 7.6%; P < .05), lower expansion mismatch ratio (113.8% ± 14.6% vs 103.8% ± 11.7%; P = .012), and lower distal SINE rate (4/23 [17.4%] vs 0/45 [0%]; P = .011). Compared with the TEVAR group, the false lumen was reduced significantly at the level of the RBS distal edge (P = .029).

CONCLUSIONS

Excessive distal oversizing and distal expansion mismatch ratio may contribute to the occurrence of distal SINE. The RBS technique reduced the incidence of distal SINE. Based on our midterm and long-term observations, implantation of an RBS may improve aortic remodeling.

Clinical Outcomes for Endovascular Repair of Thoracic Aortic Disease Using the Seal Thoracic Stent Graft: A Korean Multicenter Retrospective Study

PURPOSE

To investigate the midterm outcomes of thoracic endovascular aneurysm repair (TEVAR) with the use of the Seal stent graft for four categories of thoracic aortic disease.

MATERIALS AND METHODS

This retrospective multicenter study evaluated the records of 216 Korean patients who underwent TEVAR with the Seal stent graft during 2007-2010. The study outcomes were (i) perioperative death, (ii) endoleak, (iii) repeat intervention, (iv) aortic-related death, and (v) all sudden unexplained late deaths.

RESULTS

The overall technical success rate was 94% (203 cases), and the disease-specific rates were 97% (88 cases) for aneurysms, 96% (71 cases) for dissections, 82% (32 cases) for traumatic aortic disease, and 100% (12 cases) for intramural hematoma and/or penetrating aortic ulcer. There were 6 acute surgical conversions (2 for aneurysms and 4 for dissections). There were 18 endoleaks, 4 retrograde ascending aortic dissections, and 6 stent graft-induced new entries. The 1-, 3-, and 5-year overall survival rates were 93% ± 3, 90% ± 4, and 90% ± 4, respectively.

CONCLUSIONS

TEVAR with the Seal thoracic stent graft provided a high technical success rate and low mortality and complication rates during midterm follow-up. However, additional long-term studies are needed to evaluate the durability and late complications associated with this device.

Initial clinical experience with the Zenith alpha stent-graft

PURPOSE

To assess safety and short-term efficacy of endovascular repair of the thoracic aorta with the new Zenith Alpha stent-graft.

METHODS

Between August 2010 and May 2014, 33 patients (21 men; mean age 73.2±9.0 years) were treated Zenith Alpha stent-graft (group ZA). Outcomes of this group were compared with those of 34 patients (25 men; mean age 70.3±8.5 years) treated contemporaneously with the Zenith TX-2 for the same pathologies (group TX). The primary outcome measure was technical success. Data on iliac tortuosity, minimum access vessel diameter, and previous unsuccessful treatment with other endografts was also recorded.

RESULTS

Technical success was 93.9% in group ZA and 91.2% in group TX (p=0.67). There was no case of surgical death or conversion to open repair in either group. Two (6%) type I endoleaks occurred in group ZA and 3 (9%) in group TX (p=0.67). Three patients died within 30 days in group ZA vs. none in group TX (p=0.07). Mean minimum access vessel diameter was significantly smaller (5.07 vs. 6.65 mm, p=0.002) and iliac tortuosity indices significantly higher in group ZA (1.34 vs. 1.25, p=0.02). Access vessel complications occurred in 1 (3%) patient in group ZA and 4 (12%) patients in group TX (p=0.17). Significantly more patients in group ZA (6, 18%) were unsuccessfully treated previously with other endografts vs. none in group TX (p=0.01).

CONCLUSION

The new Zenith Alpha appears to be equally as safe and efficacious as the Zenith TX-2 while being used in patients with demanding access vessel morphology.

A biomimetic approach for designing stent-graft structures: Caterpillar cuticle as design model

Stent-graft (SG) induced biomechanical mismatch at the aortic repair site forms the major reason behind postoperative hemodynamic complications. These complications arise from mismatched radial compliance and stiffness property of repair device relative to native aortic mechanics. The inability of an exoskeleton SG design (an externally stented rigid polyester graft) to achieve optimum balance between structural robustness and flexibility constrains its biomechanical performance limits. Therefore, a new SG design capable of dynamically controlling its stiffness and flexibility has been proposed in this study. The new design is adopted from the segmented hydroskeleton structure of a caterpillar cuticle and comprises of high performance polymeric filaments constructed in a segmented knit architecture. Initially, conceptual design models of caterpillar and SG were developed and later translated into an experimental SG prototype. The in-vitro biomechanical evaluation (compliance, bending moment, migration intensity, and viscoelasticity) revealed significantly better performance of hydroskeleton structure than a commercial SG device (Zenith(™) Flex SG) and woven Dacron(®) graft-prosthesis. Structural segmentation improved the biomechanical behaviour of new SG by inducing a three dimensional volumetric expansion property when the SG was subjected to hoop stresses. Interestingly, this behaviour matches the orthotropic elastic property of native aorta and hence proposes segmented hydroskeleton structures as promising design approach for future aortic repair devices.

Acute Traumatic Thoracic Aortic Injury: Considerations and Reflections on the Endovascular Aneurysm Repair

Traumatic rupture of the thoracic aorta is a life-threatening lesion and it occurs in 10 to 30% of fatalities from blunt thoracic trauma and is the second most common cause of death after head injury. Immediate surgery is often characterized by a high mortality and morbidity rate. Delayed repair of traumatic aortic injuries has significant survival benefits and a much lower mortality rate compared with early open repair. Despite developments in operative techniques, there still remains considerable operative mortality and morbidity associated with a surgical approach even if delayed. Endovascular stent grafts for the thoracic aorta represents an alternative to the conventional approach for traumatic aortic rupture. Because of the lower invasivity avoiding thoracotomy and use of heparin, endovascular repair can be applied in acute patients without the risk of destabilizing pulmonary, head or abdominal traumatic lesions. However, despite the good deal of convincing evidence for endovascular treatment for thoracic aortic diseases and for traumatic aortic injuries as a valid and efficacious alternative to surgery, several reports show a variety of late complications of thoracic endografts especially for first-generation stent-grafts. In light of this, is the endovascular treatment really safe, efficacious and free from complications in the long term? This manuscript aims to offer a moment of reflection on this important chapter of aortic pathology.

Computed tomography angiography of hybrid thoracic endovascular aortic repair of the aortic arch

Endovascular repair of the aorta has traditionally been limited to the abdominal aorta and, more recently, the descending thoracic aorta. However, recently hybrid repairs (a combination of open surgical and endovascular repair) have made endovascular repair of the aortic arch possible. Hybrid repair of the aortic arch typically involves an open surgical debranching procedure that allows for revascularization of the aortic arch vessels and subsequent endovascular stent placement. These approaches avoid the deep hypothermic circulatory arrest required for full, open surgical repair of the aortic arch. In hybrid repairs, the stent landing zone determines which branch vessels will be covered and therefore need revascularization. This article will review the preprocedure assessment with computed tomography angiography, techniques for revascularization and postprocedure complications.

Comparison of long-term clinical outcome between patients with chronic versus acute type B aortic dissection treated by implantation of a stent graft: a single-center report

BACKGROUND

Stent grafting for treatment of type B aortic dissection has been extensively used. However, the difference in the long-term clinical outcome between patients with chronic versus acute type B aortic dissection remains unknown. This study aimed to analyze the difference in long-term clinical outcome after endovascular repair for patients with chronic (≥2 weeks) versus acute (<2 weeks) type B aortic dissection.

METHODS

Between May 2000 and June 2011, a total of 174 patients with type B aortic dissection (56 chronic, 118 acute) treated by endovascular repair were studied prospectively. Follow-up three-dimensional computed tomography scanning and aortoangiography were scheduled at 3-6 months after the index procedure. Propensity score matching was used to compare the difference in the endpoint between the two groups.

RESULTS

The procedure-related event rate was 18.6% in the acute group and 5.4% in the chronic group (P = 0.021), but this difference became nonsignificant after propensity score matching. At the end of follow-up (mean 2.49 years), overall and aorta-related mortality was 11.0% and 7.6%, respectively, in the acute group, and was not significantly different from that in the chronic group (3.6% and 3.6%, P = 0.148 and P = 0.506, respectively). Both false and true lumina showed significant remodeling over time, with >93% complete false-lumen thrombosis. Untreated tear and type I endoleak were predictors of clinical events during follow-up.

CONCLUSION

Comparable long-term clinical results were achieved in patients with chronic or acute type B aortic dissection after implantation of a stent graft.

Restrictive bare stent for prevention of stent graft-induced distal redissection after thoracic endovascular aortic repair for type B aortic dissection

BACKGROUND

Stent graft-induced distal redissection (SIDR) is one of the major concerns in the durability of endovascular repair for complicated Stanford type B aortic dissection. The characteristics and means of prevention of this complication remain unknown.

METHODS

From April 1997 to March 2010, 674 patients with type B aortic dissections were treated primarily by thoracic endovascular aortic repair (TEVAR) at our center. Criteria for inclusion in this study were treatment primarily with TEVAR and an estimated mismatch rate (ratio of distal diameter of stent graft to long diameter of true lumen) greater than 120%. By this protocol, 465 patients were included in this study and were retrospectively analyzed. Among them, 266 patients were treated in the acute phase, and 199 were treated in the chronic phase.

RESULTS

A total of 311 patients were treated with standard TEVAR and 154 patients with TEVAR + restrictive bare stent (RBS). The preoperative mismatch rate (measured as the preoperative long diameter of the true lumen at the level of the intended distal end of the stent graft) of the SIDR was significantly higher than that of the non-SIDR (192.7 ± 54.9% vs 131.9 ± 10.4%; P ＜ .05). The follow-up mismatch rate of the SIDR was significantly higher than that of the non-SIDR (145.4 ± 34.6 vs 120.3 ± 16.1; P ＜ .05). Compared with the standard TEVAR, TEVAR + RBS was associated with a lower incidence of SIDR (0% vs 2.9%; P = .033) and less secondary intervention (3.9% vs 9.3%; P = .040). Placement of the RBS significantly expanded the true lumen at the level of the descending aorta with the narrowest true lumen and at the level of the distal end of the stent graft.

CONCLUSIONS

The mismatch between the distal diameter of the stent graft and the diameter of the compressed true lumen seems to be the major factor in the occurrence of SIDR. Placement of an RBS, as an adjunctive technique to TEVAR, could reduce the incidence of SIDR. On the basis of early- to midterm observations, RBSs may improve morphological remodeling of the dissected aorta at certain levels.

The role of mandatory lifelong annual surveillance after thoracic endovascular repair

Thoracic endovascular aortic repair (TEVAR) has become an attractive and well-accepted option for the management of the various thoracic aortic pathologies that vascular surgeons are confronted with. As in the abdominal aorta, current management trends include the treatment of younger patients with longer life expectancies, raising the issue of postoperative surveillance. There are several relevant differences between these anatomic areas when it comes to surveillance, including the relative inaccessibility of the thoracic aorta to ultrasound interrogation and the increased variability of thoracic aortic pathologies and post-TEVAR complications. In addition, concerns regarding radiation-induced carcinogenesis and contrast-induced nephropathy reduce the enthusiasm of many surgeons for regular computed tomography surveillance. Most agree that surveillance is important after TEVAR, but the method, duration, and frequency of that surveillance is much less clear and is the topic of this debate.

Endovascular approaches and perioperative considerations in acute aortic dissection

Aortic dissections remain complicated management issues both in the acute setting and in the chronic setting. Acute problems revolve around malperfusion syndromes or rupture, whereas chronic issues progress from the development of aneurysms in the residual dissected aorta. Endovascular approaches to dealing with these difficult situations are being used more frequently to treat acute issues in type B dissections and prevent secondary complications in type A dissections that may require significant intervention in the future. This article discusses the endovascular approaches employed in the care of acute dissections with particular attention toward the anesthetic considerations involved in these challenging cases.

Incidence and outcomes after infolding or collapse of thoracic stent grafts

OBJECTIVE

Device-related complications in the thoracic aorta are partly due to the unavoidable proximal angulation and increased flow-related forces. The present study evaluated the incidence, predictors, and outcome of the complication of infolding with the GORE TAG thoracic endoprosthesis (TAG device) to better understand the factors that might help predict these events.

METHODS

We reviewed all complaints reported to W. L. Gore and Associates (Flagstaff, Ariz) related to device infolding after the use of the GORE TAG device on or before December 2008. Events related to device infolding were evaluated. Reporting physicians and local company representatives were contacted, when necessary, to assemble all available imaging, data, and outcomes related to these case reports. When available, computed tomography images were reviewed to confirm aortic landing zone diameters, which were subsequently compared with the implanted device size.

RESULTS

From 1998 through December 2008, device infolding was reported in 139 patients (mean age, 40 ± 17 years; 73.4% men) from 33,289 device implants (reported incidence, 0.4%). Events were noted in implants for trauma (60%), dissection (19%), aneurysm (10%), and other (9%) and unknown (2%) etiologies. In 77 patients with available imaging, the average minimum aortic diameter was 21.4 ± 4.4 mm. The mean device diameter was 28.5 ± 3.5 mm, with an average oversizing of nearly 33%. Of reported patients, 51% were asymptomatic, with the diagnosis being made on routine chest imaging. Time to diagnosis was 76 ± 222 days (median, 9.5 days). Only 16 patients received no intervention after the diagnosis of device infolding, all of whom were asymptomatic. The other 123 patients underwent 135 interventions. Of these, 30 patients (24%) underwent open surgical conversion and complete or partial endograft removal. The other interventions included a variety of endovascular techniques, such as large balloon-expandable stent(s) in 40%, relining with additional endograft(s) in 31%, and repeat ballooning in seven patients. Ten patients died after device infolding, all after one or more attempts to repair the infolded device: five died of symptoms related to the infolding and five secondary to the intervention undertaken to correct the device infolding.

CONCLUSIONS

TAG device infolding appears to be an infrequent event, primarily occurring in young trauma patients secondary to excessive oversizing and severe proximal aortic angulation. However, there clearly exists a need for devices that treat such patients. As a result, future device designs should consider the compression failure mode when being designed in order to help prevent such events.

Preprocedural planning for endovascular stent-graft placement

Endovascular stent grafts have become a viable treatment for aortic thoracic and abdominal aneurysms in both elective and emergent situations. Computed tomographic (CT) angiography is the primary tool for determining eligibility for this procedure. This article discuses the preprocedural evaluation of an endovascular stent candidate. Evaluation begins with identification of the aneurysm pathology and its relationship to treatment efficacy. The radiologist must evaluate the aneurysm geometry for compatibility with stent hardware. Aneurysm features that suggest a contraindication must be recognized. Procedures that involve a combination of endovascular stenting and surgical revascularization are discussed so that the reader understands the limits of stent eligibility. Vascular access for stent placement must also be evaluated for the ability to accommodate stent delivery. The radiologist also must be familiar with CT imaging protocols and alternative methods of imaging that can evaluate stent feasibility. The utility of three-dimensional processing is discussed.

Hybrid repair of aortic arch aneurysm in high-risk patients

OBJECTIVES

Morbidity and mortality after conventional surgery of aortic arch aneurysms remain high. Alternative techniques are the subject of this report.

METHODS AND RESULTS

Open surgery requires cardiopulmonary bypass and hypothermic circulatory arrest. Thoracic endovascular aneurysm repair has a less invasive therapeutic alternative. The number of high-risk patients has considerably increased over the past decade. The proximity of the aneurysm to the supraaortic vessels makes it difficult to achieve a satisfactory proximal landing zone for endovascular stenting. Two methods have been proposed to address this issue: branched stent grafts and extraanatomic bypass, defined as a hybrid approach, which combines aortic debranching and endovascular procedures. Experience with hybrid repair is limited. Today there are no formal guidelines for the management of aortic arch aneurysm in high-risk patients.

CONCLUSION

Hybrid repair of aortic arch aneurysm in high-risk patients is a feasible and safer option.

Incomplete endograft apposition to the aortic arch: bird-beak configuration increases risk of endoleak formation after thoracic endovascular aortic repair

PURPOSE

To determine the clinical importance of the bird-beak configuration after thoracic endovascular aortic repair (TEVAR).

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the requirement to obtain informed consent from patients. Sixty-four patients (40 men, 24 women; mean age, 64 years) who underwent TEVAR were evaluated. The treated diseases included dissection (n = 29), degenerative aneurysm (n = 13), acute traumatic transection (n = 8), pseudoaneurysm (n = 4), penetrating aortic ulcer (n = 6), intramural hematoma (n = 2), and mycotic aneurysm (n = 2). Bird-beak configuration, defined as the incomplete apposition of the proximal endograft with a wedge-shaped gap between the device and the aortic wall, was assessed with postprocedural CT angiography. The presence and length of the bird-beak configuration were compared with the formation of endoleaks and adverse clinical events.

RESULTS

Endoleaks were detected in 26 (40%) of the 64 patients, including 14 with type Ia endoleak formation, one with type Ib endoleak formation, six with type II endoleak formation (from the left subclavian artery), two with type IIo endoleak formation (from other arteries), and three with type III endoleak formation. Bird-beak configuration was observed in 28 (44%) of 64 patients and correlated significantly with the risk of developing a type Ia or IIa endoleak (P < .01). Mean bird-beak length was significantly longer (P < .01) in patients with a type Ia or II endoleak (mean length, 14.3 and 13.9 mm, respectively) than in patients without endoleaks (mean length, 8.4 mm). Adverse events included early aortic-related death in three patients, additional treatment for endoleak in eight patients, and stent-graft collapse or infolding in six patients.

CONCLUSION

Detection of bird-beak configuration is helpful in the prediction of adverse clinical events after TEVAR.

Challenging endovascular repair of a critical aortic endograft migration and massive type III endoleak

Type III endoleaks, which may be caused by endograft disconnection, pose the risk of aneurysm enlargement and rupture because the pressure in the aneurysmatic sac tends to equal the systolic aortic pressure. We report the endovascular treatment of a critical dislocation of two thoracic aorta endografts with subsequent massive aneurysmatic pressurization of the aneurysmatic sac, which led to its impending rupture. The aberrant migration of both endografts required a combined, right humeral and left femoral, approach to capture the guide wire with an endovascular snare in the aneurismal sac. Several maneuvers were necessary to avoid trapping the guide wire in one of the bare stents. A final 'push-pull' technique was used to loop the wire and advance the new endografts into the ascending aorta to achieve a correct exclusion of the endoleaks. The patient suffered a perioperative stroke which could have been a complication of wire manipulation in the highly atheromatous aortic arch. A review of several maneuvers which may be taken to prevent these complications has been performed.

Electromagnetic navigation for thoracic aortic stent-graft deployment: a pilot study in swine

PURPOSE

To determine the feasibility of electromagnetic tracking as a method to augment conventional imaging guidance for the safe delivery, precise positioning, and accurate deployment of thoracic aortic endografts.

MATERIALS AND METHODS

Custom guide wires were fabricated, and the delivery catheters for thoracic aortic endoprostheses were retrofitted with integrated electromagnetic coil sensors to enable real-time endovascular tracking. Preprocedure thoracic computed tomographic (CT) angiograms were obtained after the placement of fiducial skin patches on the chest wall of three anesthetized swine, enabling automatic registration. The stent-graft deployment location target near the subclavian artery was selected on the preprocedure CT angiogram. Two steps were analyzed: advancing a tracked glidewire to the aortic arch and positioning the tracked stent-graft assembly by using electromagnetic guidance alone. Multiple CT scans were obtained to evaluate the accuracy of the electromagnetic tracking system by measuring the target registration error, which compared the actual position of the tracked devices to the displayed "virtual" electromagnetic-tracked position. Postdeployment CT angiography and necropsy helped confirm stent-graft position and subclavian artery patency.

RESULTS

A stent-graft was successfully delivered and deployed in each of the three animals by using real-time electromagnetic tracking alone. The mean fiducial registration error with autoregistration was 1.5 mm. Sixteen comparative scans were obtained to determine the target registration error, which was 4.3 mm +/- 0.97 (range, 3.0-6.0 mm) for the glidewire sensor coil. The mean target registration error for the stent-graft delivery catheter sensor coil was 2.6 mm +/- 0.7 (range, 1.9-3.8 mm). The mean deployment error for the stent-graft, defined as deployment deviation from the target, was 2.6 mm +/- 3.0.

CONCLUSIONS

Delivery and deployment of customized thoracic stent-grafts with use of electromagnetic tracking alone is feasible and accurate in swine. Combining endovascular electromagnetic tracking with conventional fluoroscopy may further improve accuracy and be a more realistic multimodality approach.

Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) represents a novel concept for type B aortic dissection. Although life-saving in acute emergencies, outcomes and survival of TEVAR in stable dissection are unknown.

METHODS AND RESULTS

One hundred forty patients in stable clinical condition at least 2 weeks after index dissection were randomly subjected to elective stent-graft placement in addition to optimal medical therapy (n=72) or to optimal medical therapy alone (n=68) with surveillance (arterial pressure according to World Health Organization guidelines < or =120/80 mm Hg). The primary end point was all-cause death at 2 years, whereas aorta-related death, progression (with need for conversion or additional endovascular or open surgery), and aortic remodeling were secondary end points. There was no difference in all-cause deaths, with a 2-year cumulative survival rate of 95.6+/-2.5% with optimal medical therapy versus 88.9+/-3.7% with TEVAR (P=0.15); the trial, however, turned out to be underpowered. Moreover, the aorta-related death rate was not different (P=0.44), and the risk for the combined end point of aorta-related death (rupture) and progression (including conversion or additional endovascular or open surgery) was similar (P=0.65). Three neurological adverse events occurred in the TEVAR group (1 paraplegia, 1 stroke, and 1 transient paraparesis), versus 1 case of paraparesis with medical treatment. Finally, aortic remodeling (with true-lumen recovery and thoracic false-lumen thrombosis) occurred in 91.3% of patients with TEVAR versus 19.4% of those who received medical treatment (P<0.001), which suggests ongoing aortic remodeling.

CONCLUSIONS

In the first randomized study on elective stent-graft placement in survivors of uncomplicated type B aortic dissection, TEVAR failed to improve 2-year survival and adverse event rates despite favorable aortic remodeling.

Current status of thoracic endografting and its adjunctive pharmacology

BACKGROUND

Thoracic endovascular aortic repair is a promising treatment modality. The advantages in the short term include shorter hospital stay, avoidance of lengthy invasive procedures, and decreased anesthesia time. It has made possible the treatment of elderly patients with coexisting comorbidities who otherwise would be difficult candidates for open surgery.

OBJECTIVE

Although the technical aspects of thoracic endovascular procedures have been described in the literature, the adjunct pharmacology has not been discussed. The aim of this study is therefore to review the clinical pharmacology necessary for procedural details in repair of patients with aortic aneurysms and aortic dissection.

METHODS

A literature search was performed using PUBMED by combining relevant Medical Subject Heading key words. The query was subsequently limited to English language, and involving "human". The articles were assessed for their validity, importance, and applicability. The publications were analyzed and clinically important data were collected and incorporated.

RESULTS/CONCLUSION

Thoracic endovascular aortic repair is a complex procedure on a morbid cohort of patients with aortic pathologies. The pharmacotherapy is a crucial component of the procedure: It is aimed at facilitating the endovascular procedure and improving outcomes.

Standard of practice for the endovascular treatment of thoracic aortic aneurysms and type B dissections

Thoracic endovascular aortic repair (TEVAR) represents a minimally invasive technique alternative to conventional open surgical reconstruction for the treatment of thoracic aortic pathologies. Rapid advances in endovascular technology and procedural breakthroughs have contributed to a dramatic transformation of the entire field of thoracic aortic surgery. TEVAR procedures can be challenging and, at times, extraordinarily difficult. They require seasoned endovascular experience and refined skills. Of all endovascular procedures, meticulous assessment of anatomy and preoperative procedure planning are absolutely paramount to produce optimal outcomes. These guidelines are intended for use in quality-improvement programs that assess the standard of care expected from all physicians who perform TEVAR procedures.

Standard of practice for the endovascular treatment of thoracic aortic aneurysms and type B dissections

Thoracic endovascular aortic repair (TEVAR) represents a minimally invasive technique alternative to conventional open surgical reconstruction for the treatment of thoracic aortic pathologies. Rapid advances in endovascular technology and procedural breakthroughs have contributed to a dramatic transformation of the entire field of thoracic aortic surgery. TEVAR procedures can be challenging and, at times, extraordinarily difficult. They require seasoned endovascular experience and refined skills. Of all endovascular procedures, meticulous assessment of anatomy and preoperative procedure planning are absolutely paramount to produce optimal outcomes. These guidelines are intended for use in quality-improvement programs that assess the standard of care expected from all physicians who perform TEVAR procedures.