Bird-beak Configuration Research Articles

Evaluation of multiparametric MRI differentiating pleomorphic adenoma from schwannoma in parapharyngeal space.

This study aimed to investigate whether multiparametric magnetic resonance imaging (MRI) including dynamic contrast-enhanced (DCE) and diffusion weighted (DW) MRI can differentiate pleomorphic adenoma (PA) from schwannoma in the parapharyngeal space. Forty-six patients with pathologically proven PAs and 47 schwannomas in the parapharyngeal space were enrolled. All patients underwent conventional MRI, and DW-MRI and DCE-MRI were performed in 30 and 33 patients, respectively. Fisher's exact, Mann-Whitney-U tests and Independent samples t-test were used to compare variables between PAs and schwannomas. Multivariate logistic regression analysis was used to examine the diagnostic performance of MRI parameters. The PAs usually show lobulation sign, posterior displacement of ICA and attached to the parotid gland deep leaf, while bird beak configuration, anterior displacement of ICA and involvement of foramen jugular were more commonly seen in the schwannomas(all p < 0.001). The washout rate of PAs was found to be higher than that of schwannomas (p = 0.035), whereas no significance was found in the other DCE-MRI parameters and in ADCs(p > 0.05). Using a combination of conventional MRI features including lobulation sign, bird beak configuration, direction of internal carotid artery(ICA) displacement and attached to the parotid gland in multivariate logistic regression analysis, sensitivity, specificity, and accuracy in differential diagnosis of PAs and schwannomas were 97.8%, 91.5% and 94.6%, respectively. Conventional MRI can effectively differentiate PAs from schwannomas in the parapharyngeal space with a high diagnostic accuracy. The DCE-MRI and DWI have limited added diagnostic value to conventional MRI in the differential diagnosis.

Analysis of Aortic Arch Hemodynamics With Simulated Bird's Beak Effects.

The objective of this study was to investigate the flow effects in different degrees of thoracic aortic stent graft protrusion extension by creating bird beak effect simulations using accurate 3D geometry and a realistic, nonlinear, elastic biomechanical model using computer-aided software SolidWorks. Segmentation in 3D of an aortic arch from a computed tomography (CT) scan of a real-life patient was performed using SolidWorks. A parametric analysis of three models was performed: (A) Aortic arch with no stent, (B) 3mm bird-beak configuration, and (C) 6.5mm bird-beak configuration. Flow velocity, pressure, vorticity, wall shear stress (WSS), and time average WSS were assessed. The flow velocity in Model A remained relatively constant and low in the area of the ostium of the brachiocephalic artery and doubled in the left subclavian artery. On the contrary, Models B and C showed a decrease in velocity of 52.3 % in the left subclavian artery. Furthermore, Model B showed a drop in velocity of 82.7% below the bird-beak area, whereas Model C showed a decline of 80.9% in this area. The pressure inside the supra-aortic branches was higher in Model B and C compared with Model A. In Model A, vorticity only appeared at the level of the descending aorta, with low to non-vorticity in the aortic arch. In contrast, Models B and C had an average vorticity of 241.4Hz within the bird beak area. Regarding WSS, Model A, and Model B shared similar WSS in the peak systolic phase, in the aortic arch, and the bird beak area, whereas Model C had an increased WSS by 5Pa on average at these zones. In the present simulations' lower velocities, higher pressures, vortices, and WSS were observed around the bird beak zone, the aortic arch, and the supra-aortic vessels.

Impact on early outcome after endovascular repair of type B dissection without proximal landing zone using Castor single-branched stent graft-a retrospective cohort study.

The early safety and efficacy of Castor branch stents have been demonstrated. However, the effect of aortic arch morphology on endovascular therapy remains an unresolved issue. This study aims to assess the impact of aortic arch morphology on the early outcomes of endovascular repair using Castor stent graft in patients who have acute type B aortic dissection involving the left subclavian artery (LSA). This is a retrospective cohort study. From January 2019 to December 2021, forty-one patients scheduled for thoracic endovascular aortic repair (TEVAR) of TBADs from Beijing Anzhen Hospital were enrolled in this retrospective cohort study and divided into two groups based on the length of the proximal landing zone left common carotid artery-LSA (PLZ LCCA-LSA), specifically the distance between the LCCA and the LSA (group A ≤10 mm and group B >10 mm). The study recorded technical success, mortality and aortic-related post-operative adverse events. Morphological indices were analyzed including the bird-beak configuration. The bird-beak configuration refers to the wedge-shaped gap between the undersurface of the endograft and the lesser curvature of the arch. The relationship between the risk of bird-beak configuration and PLZ was assessed with logistic regression analysis. Meanwhile, the relationship between the risk of aortic-related adverse events and bird-beak configuration was assessed with logistic regression analysis. Follow-up data were analyzed by Kaplan-Meier life table analysis. The study included 41 patients with a mean age of 63.1±9.2 years, of which 80.5% were male. 18 patients from group A and 23 patients from group B were included in the comparative analysis. There were no significant differences in aortic-related adverse events, bird-beak phenomenon and re-intervention between groups A and B in 30-day outcomes. Six-month outcomes: aortic-related adverse events and the bird-beak phenomenon were observed in 11 (26.8%) and 12 (29.3%) patients, respectively. There was a significant difference in the occurrence of aortic-related adverse events (P=0.036) and bird-beak phenomenon (P=0.002) between groups A and B. In comparison to group B, the aortic-related adverse event rate was significantly higher in group A, with event-free rates of 83.3%, 83.3%, and 72.2% at 1, 3, and 6 months, respectively (P=0.020). Multivariable logistic regression analyses revealed that PLZ LCCA-LSA length [odds ratio (OR) 0.79; 95% CI: 0.64 to 0.97; P=0.026] was significantly associated with the occurrence of the bird-beak configuration, and bird-beak (OR 17.19; 95% CI: 2.24 to 131.81; P=0.006) was a significant risk factor for aortic-related adverse events. TEVAR with LSA revascularization has good early outcomes. However, it is more susceptible to aortic adverse events when the PLZ LCCA-LSA is less than 10 mm in length. This should be carefully considered, taking into account the risks and benefits.

A retrospective study of endovascular repair of aortic dissection with aberrant right subclavian artery

Abstract: OBJECTIVES: Aortic dissection with aberrant right subclavian artery (ARSA) is rare but fatal, with its optimal treatment remaining controversial. In this retrospective study, we presented the outcome of endovascular repair for these patients, aiming to evaluate the efficacy and safety of this technique. MATERIALS AND METHODS: From January 2016 to January 2022, seven patients diagnosed with aortic dissection with ARSA in the First Affiliated Hospital of Sun Yat-sen University were enrolled. All these seven patients received thoracic endovascular aortic repair (TEVAR) within 1 week after their admission to our center. The data of baseline characteristics, imaging parameters, perioperative information, and follow-up were collected till March 2023. RESULTS: The mean age was 48.57 ± 9.41 years. Kommerell diverticulum was found in 2 (28.6%) patients. Among these seven patients, 4 (57.1%) were treated by TEVAR + branched stent graft + chimney technique, 2 (28.6%) were treated by TEVAR + chimney technique, and 1 (14.3%) was treated by TEVAR + chimney and periscope techniques. The mean time of procedures was 196.67 ± 31.18 min. Clinical success was achieved in 6 (85.7%) patients, while 1 (14.3%) patient died of nonaortic related cause. Bird beak configuration was discovered in 4 (57.1%) patients with an average length of 17.87 ± 3.93 mm and angle of 21.9° ±3.70°. One early type I endoleak and one mild cerebral ischemia were discovered, and recovered spontaneously before discharge. The diameter of the aorta remained stable, and no complication was found during the follow-up of the six patients. CONCLUSION: Endovascular repair of aortic dissection with ARSA was feasible and safe, with a favorable early to mid-term outcome.

Prediction of bird-beak configuration in thoracic endovascular aortic repair preoperatively using patient-specific finite element simulations

ObjectivesFormation of bird-beak configuration in thoracic endovascular aortic repair (TEVAR) has been shown to be correlated with the risk of complications such as type Ia endoleaks, stent graft migration, and collapse. The aim of this study was to use patient-specific computational simulations of TEVAR to predict the formation of bird-beak configuration preoperatively. MethodsPatient-specific TEVAR computational simulations are developed using a retrospective cohort of patients treated for thoracic aortic aneurysm. The preoperative computed tomography images were segmented to develop three-dimensional geometry of the thoracic aorta. These geometries were used in finite element simulations of stent graft deployment during TEVAR. Simulated results were compared against the postoperative computed tomography images to assess the accuracy of simulations in predicting the proximal position of a deployed stent graft and presence of bird-beak. In cases with a bird-beak configuration, the length and angle of the bird-beak were measured and compared between the simulated and postoperative results. ResultsTwelve TEVAR patient cases were simulated. Computational simulations were able to accurately predict whether the proximal stent graft was fully apposed, proximal bare stents were protruded, or bird-beak configuration was present. In three cases with bird-beak configuration, simulations predicted the length and angle of the bird-beak with less than 10% and 24% error, respectively. Other factors such as a small aortic arch angle, small oversizing value, and landing zones close to the arch apex may have played a role in formation of bird-beak in these patients. ConclusionsComputational simulations of TEVAR accurately predicted the proximal position of a deployed stent graft and the presence of bird-beak preoperatively. The computational models were able to predict the length and angle of bird-beak configurations with good accuracy. These simulations can provide insight into the surgical planning process with the goal of minimizing bird-beak occurrence.

Chimney Technique and Single-Branched Stent Graft for the Left Subclavian Artery Preservation During Zone 2 Thoracic Endovascular Aortic Repair for Type B Acute Aortic Syndromes.

The purpose of this study was to evaluate the efficacy and safety of zone 2 thoracic endovascular aortic repair assisted by the chimney technique or single-branched stent graft for the preservation of the left subclavian artery, and summarize our single-center experience with the techniques. From February 2017 to June 2020, 137 patients who underwent left subclavian artery revascularization during zone 2 thoracic endovascular aortic repair were enrolled. Patients had acute type B aortic dissection and penetrating aortic ulcer associated with intramural hematoma. The chimney technique was performed in 68 patients (group A), and single-branched stent graft was deployed in 69 patients (group B). All procedures were performed during the acute phase. Primary technical success, immediate postoperative endoleak, neurologic complications (stroke or spinal cord ischemia), 30-day mortality, 1-year technical success, all-cause mortality, patency of the left subclavian artery, and reintervention were analyzed. Comparing the occurrence of the Bird-Beak Configuration, defined as a gap between the aortic wall and the sent graft with stent protrusion into the aortic lumen more than 5 mm, was also performed. Primary technique success was achieved in 66 and 67 patients in groups A and B, respectively. The incidence of immediate postoperative endoleak, neurologic complications (stroke or spinal cord ischemia), and 30-day mortality were 5.9%, 1.5%, and 4.4% in group A, and 2.9%, 2.9%, and 2.9% in group B, respectively. During follow-up, the 1-year technical success rate was similar in both groups. All-cause mortality was similar in both groups (3.1% in group A and 4.5% in group B). The patency of the left subclavian artery was not significantly different between the 2 groups with 2 and 3 occlusions in groups A and B, respectively. The rate of reintervention was higher in group B (3.1% vs 1.6%, p=0.536), with a non-significant difference. Bird-Beak Configuration was more prominent in group B with the incidence of 59.42%. Acting as minimally invasive alternatives, both techniques are feasible for left subclavian artery preservation during zone 2 thoracic endovascular aortic repair for type B acute aortic syndromes with encouraging mid-term outcomes. Long-term follow-up is required to confirm these findings.

A modeling framework for computational simulations of thoracic endovascular aortic repair.

Thoracic endovascular aortic repair (TEVAR) is a minimally invasive treatment for thoracic aortic conditions including aneurysms and is associated with a number of postoperative stent graft related complications. Computational simulations of TEVAR have the potential to predict surgical outcomes and complications preoperatively. When using simulations for stent graft design and prediction of complications in a population, it is difficult to generalize patient-specific TEVAR computational models due to patient variability. This study proposes a novel modeling framework for creating realistic population-based computational models of TEVAR focused on aneurysms that allow for developing various clinically relevant geometric configurations and scenarios that are not easily attainable with limited patient data. The framework includes a methodology for developing population-based thoracic aortic geometries and defining age-dependent aortic tissue material models, as well as detailed steps and boundary conditions for finite element modeling of stent graft deployment during TEVAR. The simulation framework is illustrated for predicting the formation of a bird-beak configuration, a wedge-shaped gap at the proximal end of the deployed stent graft in TEVAR that leads to incomplete seal. A baseline TEVAR simulation model was developed along with three simulations in which the value of aortic curvature, aortic arch angle, or aortic tissue properties varied from the baseline model. Analyzing the length and angle of the bird-beak configuration in each case shows that the bird-beak size is sensitive to different values of the aortic geometry highlighting the importance of using realistic parameter values.

Identification of geometric and mechanical factors predictive of bird-beak configuration in thoracic endovascular aortic repair using computational models of stent graft deployment

ObjectiveFormation of a bird-beak configuration in thoracic endovascular aortic repair (TEVAR) has been shown to be influenced by various factors. However, the main cause of bird-beak formation remains poorly understood. The hypothesis has been that the geometric and mechanical properties of both the aorta and the stent graft contribute to the formation and extent of a bird-beak configuration. The goal of the present study was to use parameter-based computational simulations of TEVAR to predict for bird-beak formation and identify its most significant contributing factors. MethodsIn the present study, we considered five parameters for the computational simulations of TEVAR, including aortic curvature, aortic arch angle, age as a surrogate for thoracic aortic tissue properties, TEVAR landing zone, and stent graft oversizing. Using an experimental design approach, computational models for 160 TEVAR scenarios were developed by varying the values of the simulation parameters within clinically relevant ranges. The bird-beak length and angle were used as metrics to evaluate the simulation results. Statistical analysis of the simulation data using a random forest model was conducted to identify significant parameters and interactions. ResultsThe mean ± standard deviation of the bird-beak length and angle across 160 simulations were 4.32 ± 4.87 mm and 9.16° ± 12.21°, respectively. The largest mean bird-beak length and angle were found in the most distal location in zone 0 (10.04 mm) and zone 2 (21.48°), respectively. An inverse correlation was found between the aortic arch angle and the bird-beak length and angle. In ∼75% of the scenarios, increased stent graft oversizing either fully resolved the presence of the bird-beak configuration or had reduced its size. In the remaining 25%, oversizing minimally changed the bird-beak length and enlarged the bird-beak angle, which mainly occurred in cases with a smaller aortic arch angle and landing zones near the arch apex. This was justified by the mechanism of stent graft bending in the arch angulation. The aortic curvature and tissue properties were shown to be statistically insignificant in relation to bird-beak formation. ConclusionsSignificant parameters predictive of a bird-beak configuration in TEVAR were identified, and the trends in which each parameter influenced the bird-beak size were determined. The findings from the present study can inform the surgical planning and device selection process with the goal of minimizing bird-beak formation.

Predictive Factors for Endoleaks and Aneurysm Enlargement after Thoracic Endovascular Aortic Repair of Thoracic Aortic Aneurysm

Objective: To analyze the incidence and predictive factors of endoleaks and associated increased aneurysm size after thoracic endovascular aortic repair (TEVAR). Materials and Methods: The medical records and computed tomography (CT) angiography imaging of 69 patients with thoracic aortic aneurysm that underwent thoracic endovascular aortic repair at a single institute between June 2012 and May 2019 were reviewed. The incidences of endoleak were calculated. The patients’ demographic data, operative details, and imaging data were collected. The risk factors of endoleak occurrence were analyzed between endoleak and non-endoleak groups. The association between endoleak and aneurysm enlargement was also evaluated. Results: Endoleaks were noted in twenty-nine cases (42.0%) including four type Ia (5.8%), six type Ib (8.7%), seventeen type II (24.6%), and two type III (2.9%). Fifty-nine percent of the patients with endoleak were found with aneurysm enlargement. The predictive factors of endoleak were bird beak configuration and distal neck length of less than 20 mm (p=0.014 and 0.019, respectively). For type Ia, endoleak presented with short proximal neck length (p=0.031). Short distal neck and angulation of distal stent less than 160 degrees were the predictive factors of type Ib endoleak (p=0.045 and &lt;0.001, respectively). Increased number of intercostal arteries is the only significant risk factor of type II endoleak (p=0.005). The other complications were endograft migration in about 5.8%, endograft infection in 2.9%, cerebrovascular complications in 5.8%, and ruptured aortic aneurysm in 2.9%. Conclusion: Interval follow up CT angiography is recommended to detect endoleak and other late complications after TEVAR. Special considerations are noted in the underlying renal insufficiency and the young patient for radiation dose in long term follow up. Keywords: Endoleak, Thoracic endovascular aortic repair, Thoracic aortic aneurysm, CT angiography, Aneurysm enlargement

Association between aortic arch angulation and bird-beak configuration after thoracic aortic stent graft repair of type B aortic dissection.

The goal of this study was to investigate factors favouring the bird-beak configuration after thoracic endovascular aortic repair (TEVAR) for type B aortic dissection. We retrospectively analysed 76 patients with type B aortic dissection who underwent landing zone 1 and 2 TEVAR from December 2015 to January 2018. Preoperative aortic arch geometry (aortic arch length, maximal diameter and angulation), stent graft details and operative details were evaluated. A bird-beak configuration was defined as a ≥5-mm gap between the proximal end of the stent and the aortic wall of the lesser curvature. Patients were stratified into those with (n = 46) and without (n = 30) a bird-beak configuration. The baseline demographics, dissection chronicity, clinical features and implanted devices were largely similar between the 2 groups. No significant difference was observed in the arch length or maximal arch diameter. However, the mean aortic arch angulation was greater in patients with than without a bird-beak configuration (61.4° vs 51.3°; P < 0.001). No influence of either the stent graft brand or the proximal stent graft type was observed. The multivariable analysis showed that the aortic arch angulation was an independent risk factor for a bird-beak configuration (odds ratio 1.15, 95% confidence interval 1.07-1.24; P < 0.001). A cut-off angle of 59.15° was predictive of a bird-beak configuration (sensitivity 59%; specificity 77%). The preoperative aortic arch angulation was an independent predictor of a postoperative bird-beak configuration in patients with type B aortic dissection who underwent TEVAR that involved the aortic arch. An angle of >59.15° may imply a relatively hostile anatomy with a higher risk of a bird-beak configuration.

Determining the Optimal Proximal Landing Zone for TEVAR in the Aortic Arch: Comparing the Occurrence of the Bird-Beak Phenomenon in Zone 0 vs Zones 1 and 2

Purpose: To identify the optimal proximal landing zone for thoracic aortic endovascular repair (TEVAR) of aortic arch pathologies so as to avoid the bird-beak phenomenon that leads to type Ia endoleak. Materials and Methods: A retrospective single-center review was conducted of 164 patients (mean age 70.3±10.8 years, range 29–93; 127 men) who underwent repairs of the aortic arch using hybrid TEVAR from April 2008 to March 2017. The patients were divided into 2 groups according to the proximal landing zone: 43 zone 0 patients (26.2%) had total debranching TEVAR (n=18) or total endovascular aortic repair (n=25) while 121 patients (73.8%) had TEVAR landing in zones 1 (n=41) or 2 (n=80). Bird-beak configurations, endoleaks, and stent migrations were assessed on the postoperative and latest computed tomography angiography (CTA) scans. Overall survival and freedom from the bird-beak configuration, aorta-related death, and aortic events were estimated using the Kaplan-Meier method. Hazard ratios (HR) were calculated with the 95% confidence interval (CI). Results: All procedures were successful, without any 30-day mortality. There were 3 early complications (1.8%; all strokes) and 10 early endoleaks (6.1%; no type Ia). On the first postoperative CTA, 42 patients (25.6%) had a bird-beak configuration. The zone 0 patients had significantly fewer (p<0.001), shorter (p<0.004), and less angulated (p<0.001) bird-beak configurations than in zones 1–2. The mean follow-up period was 4.2 years (range 0.5–8.8). There were 18 late deaths (11.0%); only one was related to the aorta (rupture due to a type Ib endoleak in a zone 0 patient). The 5-year freedom from aorta-related death was not significantly different between groups (zone 0: 96.9% vs zones 1–2: 100%, p=0.080). On the latest CTA, 51 (31.0%) patients had a bird-beak configuration; of those, 22 (13.4%) showed >3-mm progression. The freedom from bird-beak configuration estimate was significantly higher in the zone 0 group (95.4%) vs zones 1–2 (57.8%; HR 0.10, 95% CI 0.02 to 0.31, p<0.001). There were 9 late endoleaks (4 type Ia; none in the zone 0 group). The rate of stent-graft migration was significantly lower in the zone 0 group (2.3% vs 14.1% in zones 1–2, p=0.035). Conclusion: Early and most late results in zone 0 TEVAR were equal to those in zones 1 and 2; however, there were no late type Ia endoleaks and fewer bird-beak configurations associated with zone 0 TEVAR, which suggests that zone 0 landing is advantageous for preventing these complications.

One-Year Results From the SURPASS Observational Registry of the CTAG Stent-Graft With the Active Control System

Purpose: To report the outcomes from the observational SURPASS registry, which was created to assess the performance of the Conformable TAG (CTAG) stent-graft with the Active Control System (ACS) in patients undergoing thoracic endovascular aortic repair (TEVAR) in a real-world setting. Materials and Methods: The SURPASS registry (ClinicalTrials.gov; identifier NCT03286400) was an observational, prospective, single-arm, post-market, international study that enrolled patients undergoing TEVAR using the CTAG with ACS for both acute and chronic thoracic aortic disease between October 2017 and July 2018. The CTAG with ACS features 2-stage deployment of the stent-graft and an optional angulation mechanism that modifies only the proximal end of the stent-graft. During the observation period, 127 patients (mean age 67.1±12.1 years, range 27–86; 92 men) were enrolled and treated for an array of aortic pathologies, including chronic and acute lesions and 4 ruptured descending thoracic aneurysms. The primary outcome of this study was technical success; secondary outcomes were clinical success and major adverse events at 30 days and 12 months. The numbers of 2-stage device deployments and applications of the angulation mechanism were recorded, along with the reasons for use. Results: Technical success of the TEVAR was 97.6% owing to unintentional partial coverage of supra-aortic branches in 3 cases (the vessels were patent on imaging). The stent-graft was repositioned at its intermediate diameter in 79 patients (62.2%), and the angulation feature was applied in 64 cases (50.4%), mainly to improve proximal wall apposition and orthogonality in the aorta. The desired effect was achieved in 60 cases (93.8%). There was no device compression, bird-beak configuration, fracture, or graft occlusion. The 30-day and 12-month clinical success rates were 97.6% and 92.9%, respectively. There were 3 aorta-related deaths at 30 days and a further 3 at 12 months. Fatalities were due to a retrograde type A dissection (0.8%), paraplegia, bowel ischemia, sepsis in the setting of a mycotic aneurysm, aneurysm rupture post aortoesophageal fistula, and multiorgan dysfunction syndrome. Three endoleaks (2 type Ia and 1 type III) required reintervention. Conclusion: In the SURPASS registry, the use of the CTAG device with ACS showed promising outcomes despite the challenging pathologies. The new delivery system enables a controlled staged delivery with in situ adjustments during positioning, facilitating the treatment of complex aortic disease.

Proximal Bare Stent can Prevent Bird-Beak Configuration in Aortic Arch TEVAR

Introduction - Previous studies have shown that a bird-beak configuration increases the risk of endoleak formation after thoracic endovascular aortic repair (TEVAR)1. However, the factors, which cause bird-beak configurations, are poorly understood. The purpose of this study is to assess the influences of the aortic arch morphology or the kind of implanted thoracic stent grafts on bird-beak configuration.

Impact of the Bird-Beak Configuration on Postoperative Outcome After Thoracic Endovascular Aortic Repair: A Meta-analysis

Purpose: To investigate the association between the bird-beak configuration (BBC), a wedge-shaped gap between the undersurface of a thoracic endograft and the lesser curvature of the arch after thoracic endovascular aortic repair (TEVAR), and postoperative outcome after TEVAR. Methods: The study was performed according to the PRISMA guidelines. The PubMed, EMBASE, and Cochrane databases were searched to identify all case series reporting BBC after TEVAR between 2006 and April 2018. Data analysis was performed considering the difference in the risk of complications for presence vs absence of BBC. After screening 1633 articles, 21 studies were identified that matched the selection criteria; 12 of these reported detailed information to investigate the postoperative outcome using proportion meta-analysis with a random effects model. The pooled risk difference is reported with the 95% confidence interval (CI). Heterogeneity of the included studies was assessed with the I2 statistic (low 25%, medium 50%, high 75%). Results: Complications occurred within a range of 0 to 72 months in 14.7% (95% CI 7.4% to 27.3%) of patients with BBC and in 6.3% (95% CI 2.5% to 15.4%) of patients without BBC. A cumulative incidence could not be assessed. The summary risk difference was 11.1% (95% CI −0.1% to 22.3%, p=0.052). There was significant heterogeneity (I2=85.6%). The Egger test did not show evidence of publication bias (p=0.975). When specifically considering type Ia endoleak and endograft migration, the risk difference between BBC and non-BBC patients was 8.2% (95% CI 0.3% to 16.1%, p=0.042; I2=69.0%). The specific risk difference for endograft collapse/infolding and thrombosis was 3.7% (95% CI −3.5% to 11.1%, p=0.308; I2=10.2%). Conclusion: At present the literature does not provide statistical evidence to establish an overall prognostic value of the BBC. Nevertheless, the BBC appears to be associated with a high risk of type Ia endoleak and endograft migration, which warrants specific and long-term surveillance. Clinically relevant values for BBC grading should be established to perhaps define indications for preemptive treatment based on the presence of BBC only.

Proximal Bare Stent May Reduce Bird-Beak Configuration, Which is Associated with Distal Migration of Stent Graft in the Aortic Arch

Prior studies have shown that a bird-beak configuration causes serious complications after thoracic endovascular aortic repair (TEVAR). However, factors that cause bird-beak configurations are poorly understood. The purpose of this study was to assess the influences of anatomical and device-related factors on bird-beak configuration. Sixty-eight consecutive patients (47 men, mean age, 72.8±9.8years) who underwent TEVAR with proximal fixation in zones 1 to 3 from March 2009 to February 2017 were included. Preoperative and postoperative computed tomography (CT) scans were retrospectively reviewed. Relationships between the incidence of a bird-beak configuration, preoperative aortic arch morphology, and type of stent graft were estimated. The influence of a bird-beak configuration on endograft migration over time was also estimated for 47 patients who underwent CT 12months after TEVAR. The patients' aortic arch pathologies included 52 aneurysms, 11 aortic dissections, 4 pseudoaneurysms, and 1 patent ductus arteriosus. Stent grafts with (the proximal bare stent group [PBS group]) and without (the nonbare stent group [NBS group]) a proximal bare stent were implanted in 24 and 44 patients, respectively. A bird-beak configuration was detected in 30 patients (mean length ± standard deviation [SD], 6.2±3.4mm; mean angle ± SD, 31.7±14.7°) and was significantly more frequent in the NBS group (n=29) than in the PBS group (n=1) (P<0.001). Proximal landing zone, aortic lengths, and aortic arch morphology, including the radius, tortuosity, and angulation of aortic arch curvature, were not associated with the bird-beak configuration. The migration distance after 1year was significantly longer in patients with a bird-beak configuration (3.5±6.1mm) than in patients without a bird-beak configuration (0.5±1.0mm) (P=0.015). This study demonstrated that in aortic arch TEVAR, the use of stent graft with a proximal bare stent may reduce bird-beak configuration, which is associated with distal migration of the stent graft during follow-up.

Bird's beak configuration: Thoracic aortic graft.

Bird's beak configuration: Thoracic aortic graft.

Long-Term Outcomes of Thoracic Endovascular Aortic Repair Focused on Bird Beak and Oversizing in Blunt Traumatic Thoracic Aortic Injury

The acute aortic arch angle and narrow aortic diameter in young patients may lead to bird-beak configuration and excessive oversizing of the stent graft in thoracic endovascular aortic repair (TEVAR) for blunt traumatic thoracic aortic injury (BTTAI). Little is known about the association of these factors and complications in long-term follow-up. We evaluated the long-term outcomes in terms of complications, reinterventions, and survival, focusing on the effects of bird-beak configuration and oversizing. This prospective cohort study included patients who underwent TEVAR for BTTAI in our department between October 1999 and January 2015. The main outcomes were migration, collapse, intragraft mural thrombus, reintervention, and survival and their association with oversizing and bird-beak configuration. Thirty-four patients were included. Median age was 36years, and 21% were women. Mean graft oversizing was 19% (range: 8-27%) at the proximal end and 27% (range:, -20% to 50%) at the distal end. Mean follow-up was 98months (12-198months). Seven patients presented intragraft mural thrombus, one of whom developed an occlusive parietal thrombosis 1 year after the procedure. Four patients (9%) required reintervention: postoperative revascularization of the left subclavian artery in 2 cases and aortic reinterventions in 2 others. No migration or mortality was seen during follow-up. Bird-beak configuration was seen in 65%: the mean protrusion extension was 16mm (standard deviation [SD]: 7.4mm) and the mean angle was 51° (SD: 16°). The association between the complications and bird beak was not statistically significant. Patients with complications had significantly higher proximal end oversizing (23%) than the group with no complications (17%) (P=0.0007). TEVAR for BTTAI shows good results in the long-term follow-up. Complications in our series seemed related to proximal end oversizing. Thoracic stent grafts with a smaller diameter should be available in all trauma centers to avoid excessive oversizing.

Morphology and Outcomes of Total Endovascular Treatment of Type B Aortic Dissection with Aberrant Right Subclavian Artery

To characterize the morphology of type B aortic dissection with aberrant right subclavian artery (ARSA) and present early and midterm outcomes of total endovascular treatment for affected patients. From January 2010 to December 2015, patients with ARSA and type B aortic dissection treated with total endovascular techniques were enrolled. The angle of the aortic arch was measured on pre-operative CTA. Sixty age and gender matched normal aortic arch patients with type B aortic dissection served as controls. Primary outcomes were technical success, 30 day mortality, and late survival. Secondary outcomes included in hospital morbidity, re-intervention rate, and patency of the subclavian artery. A total of 13 patients (8 men, 5 women; mean age 58 years) were included. The mean angle of the aortic arch in patients with ARSA was significantly smaller than in normal aortic arch patients (117.2°±10.8° vs. 124.2° ± 9.4°, respectively; p=.024). Simple thoracic endovascular aortic repair (TEVAR) and TEVAR plus a parallel graft technique were performed in six and seven patients, respectively. Primary technique success was achieved in 11 of the 13 (84.6%) patients. A bird beak configuration occurred significantly more frequently in patients with ARSA than in normal aortic arch patients (91.7% vs. 48.3%, respectively; p=.035). The median follow-up time was 36 months. One patient received a secondary procedure because of a new onset entry tear at the distal end of the stent graft. No posterior circulation stroke, permanent spinal cord ischaemia, or ischaemia of the upper arm was observed. Type B aortic dissection with ARSA was associated with a steep aortic arch. Total endovascular treatment for these patients was feasible and safe. Stent grafts with better flexibility and appropriate extension of the proximal landing zone with a parallel graft technique are suggested based on the observed outcomes.

Type 1a endoleak following Zone 1 and Zone 2 thoracic endovascular aortic repair: effect of bird-beak configuration.

Type 1a endoleak is one of the most severe complications after thoracic endovascular aortic repair (TEVAR), because it carries the risk of aortic rupture. The association between bird-beak configuration and Type 1a endoleak remains unclear. The purpose of this study was to analyse the predictors of Type 1a endoleak following Zone 1 and Zone 2 TEVAR, with a particular focus on the effect of bird-beak configuration. From April 2008 to July 2015, 105 patients (mean age 68.6 years) who underwent Zone 1 and 2 landing TEVAR were enrolled, with a mean follow-up period of 4.3 years. The patients were categorized into 2 groups, according to the presence (Group B, n = 32) or the absence (Group N, n = 73) of bird-beak configuration on the first postoperative multidetector computed tomography. The Kaplan-Meier event-free rate curve showed that Type 1a endoleak and bird-beak progression occurred less frequently in Group N than in Group B. Five-year freedom from Type 1a endoleak rates were 79.7% and 100% for Groups B and N, respectively (P = 0.007). Multivariable logistic regression analysis showed that dissecting aortic aneurysm (odds ratio 3.72, 95% confidence interval 1.30-11.0; P = 0.014) and shorter radius of inner curvature (odds ratio 1.09, 95% confidence interval 0.85-0.99; P = 0.025) were significant risk factors for bird-beak configuration. Multivariable Cox proportional hazard regression showed that Z-type stent graft (hazard ratio 2.69, 95% confidence interval 1.11-6.51; P = 0.030) was a significant risk factor for bird-beak progression. Appropriate stent grafts need to be chosen carefully to prevent Type 1a endoleak and bird-beak configuration after landing Zone 1 and 2 TEVAR. Patients with bird-beak configuration on early postoperative multidetector computed tomography require closer follow-up to screen for Type 1a endoleak.

Early outcomes of the conformable stent graft for acute complicated and uncomplicated type B aortic dissection

ObjectiveThe objective of this study was to evaluate the safety, efficacy, and outcomes of the conformable thoracic endograft (Conformable TAG Thoracic Endoprosthesis [CTAG]; W. L. Gore & Associates, Flagstaff, Ariz) for acute complicated and uncomplicated type B aortic dissection (TBAD). MethodsBetween February and October 2016, 52 consecutive patients with acute complicated or uncomplicated TBAD were treated with a CTAG device. We assessed safety, complications, and device conformability using intraoperative angiography and computed tomography angiography. The mean follow-up period was 8.2 ± 3.5 months (range, 4-12 months). ResultsAll patients survived through the follow-up period. No endoleaks, retrograde aortic dissection, distal new entry tear, stroke, or paraplegia was observed postoperatively. Two patients (3.8%) experienced minor wound hematomas without further treatment. Eleven patients (21.2%) underwent a chimney technique to rebuild supra-arch vessels. A bird-beak configuration was observed in seven (13.5%) patients, five of whom underwent a chimney technique. Analysis of aortic remodeling showed that the minimal true lumen area significantly increased in both complicated and uncomplicated acute TBAD (P < .001 and P = .047, respectively). Likewise, the maximal false lumen area significantly decreased in uncomplicated dissection (P = .006), but no change in maximal false lumen area was detected in complicated dissection (P = .32). ConclusionsEarly outcomes indicate that the CTAG device provides reliable clinical effectiveness and excellent conformability in treating acute complicated and uncomplicated TBAD without risk of major complications. Studies with larger sample sizes and longer follow-up periods are required to evaluate longer term outcomes.