Thoracic aortic aneurysm expansion due to late distal stent graft-induced new entry

Frozen elephant use in type a dissection: fundamentals, innovations, and pitfalls

INTRODUCTION

Type A acute aortic dissection (TA-AAD) is a great challenge for aortic surgeons. The establishment of a standardized surgical approach, particularly the determination of whether and when to address the aortic arch and the distal aorta in the same operation as the proximal aorta, is still unclear.

AREAS COVERED

Frozen elephant trunk (FET) has emerged as a valuable treatment for TA-AAD over the last decade. Here, we discuss the fundamentals and pitfalls of frozen elephant trunk procedures and present the latest innovations.

EXPERT OPINION

FET has the potential to simplify arch reconstruction in patients with complex arch tears and rupture, optimize perfusion in the distal true lumen for those with a compressed true lumen and malperfusion, address distal reentry tears, and promote false lumen thrombosis and late aortic remodeling. Nevertheless, FET is still associated with non-negligible mortality and morbidity rates. Patient selection, surgical expertise, and postoperative care remain crucial determinants in ensuring successful outcomes. Recent innovations in FET surgery involve the development of techniques to minimize or avoid hypothermic circulatory arrest and new FET devices with different arch branch configurations aiming to facilitate subsequent aortic reinterventions. We believe that both these advancements have the potential to improve patient outcomes.

Novel insights into thoracic endografts technology for prevention of distal stent-graft induced new entry (dSINE) following endovascular repair of type B aortic dissections: from bench to bedside

INTRODUCTION

Endovascular treatment of type B aortic dissections (TBAD) has currently acquired a primary therapeutic role when anatomically feasible. The main issue with thoracic endovascular aortic repair (TEVAR) for aortic dissection is the actual nature of the aortic wall, which is structurally compromised and more fragile. Indeed, a wealth of data have shown that TEVAR for TBAD will lead, in a substantial proportion of cases, to a device-related adverse event named distal stent-graft induced new entry (dSINE).

AREAS COVERED

Currently available aortic stent-grafts have not been specifically devised for the treatment of aortic dissection. A novel dissection specific stent-graft (DSSG) was developed, which is a custom-made device based on the Zenith Alpha Thoracic platform (Cook Medical). The DSSG has several unique properties that, in principle, make its use optimal in TBAD patients.

EXPERT OPINION

TEVAR in the setting of aortic dissections remains technically challenging. The occurrence of dSINE represents a unique complication in this scenario and may lead to high rates of aortic-related adverse events and need for secondary interventions. The use of a novel custom-made DSSG in the setting of chronic TBAD has been proven to be safe, feasible and effective. However, even this approach may fail to completely prevent dSINE formation.

Aortic Remodeling After Thoracic Endovascular Aortic Repair for Nonacute Uncomplicated Type B Aortic Dissection

BACKGROUND

Entry closure with thoracic endovascular aortic repair (TEVAR) for Stanford type B aortic dissection (TBAD) results in aortic remodeling recently. This study aimed to evaluate the relationship between aortic diameter or timing of surgical intervention from onset and remodeling after TEVAR for uncomplicated nonacute TBAD.

METHODS

Between April 2014 and December 2021, 83 consecutive patients underwent TEVAR for TBAD at our center. Forty patients with subacute and chronic uncomplicated TBADs with a patent false lumen, who could be followed up for at least 6 months, were included in this study. Indications for TEVAR included aortic diameter enlargement and preemptive treatment to prevent future aneurysmal changes in patients at risk of aortic diameter enlargement. Aortic remodeling was accessed, and data between the remodeling and nonremodeling groups were compared.

RESULTS

The technical success rate was 97.5%, with a type Ia endoleak remaining in 1 patient. No operative or in-hospital mortality occurred. Paraparesis occurred in only 1 patient (2.5%). Follow-up was completed at a median of 53.5 months. Late death occurred in 3 cases, but there were no aortic-related deaths. Late aortic remodeling was achieved in 22 patients (55%). The preoperative maximum aortic diameter (PMAD) in the thoracic aortic region was 51.5 mm in the nonremodeling group, significantly larger than 42.5 mm in the remodeling group (P < 0.0001). The cutoff value of the PMAD for predicting aortic remodeling was 45 mm (area under the curve, 0.917; P = 0.028). The remodeling group had an earlier time from onset to intervention than the nonremodeling group, with a cutoff value of 6.3 months (area under the curve, 0.743; P = 0.021).

CONCLUSIONS

TEVAR for nonacute uncomplicated TBAD resulted in a late aortic remodeling rate of 55%. This study suggested that a PMAD of >45 mm or a period >6.3 months between dissection onset and surgery hinders aortic remodeling after TEVAR.

Reinterventions after TEVAR

Thoracic cardiovascular aortic repair is an alternative procedure to open surgery for degenerative thoracic aortic aneurysm and thoracic aortic dissection. The advancements in graft design and imaging techniques have expanded its utility. However, the long-term patency of thoracic endovascular aortic repair (TEVAR) graft is still a concern. This review delves into the literature on re-intervention following TEVAR, highlighting factors that influence the re-intervention rate.

A CT-based predictive model for stent-induced vessel damage: application to type B aortic dissection

OBJECTIVES

The distal stent-induced new entry (distal SINE) is a life-threatening device-related complication after thoracic endovascular aortic repair (TEVAR). However, risk factors for distal SINE are not fully determined, and prediction models are lacking. This study aimed to establish a predictive model for distal SINE based on the preoperative dataset.

METHODS

Two hundred and six patients with Stanford type B aortic dissection (TBAD) that experienced TEVAR were involved in this study. Among them, thirty patients developed distal SINE. Pre-TEVAR morphological parameters were measured based on the CT-reconstructed configurations. Virtual post-TEVAR morphological and mechanical parameters were computed via the virtual stenting algorithm (VSA). Two predictive models (PM-1 and PM-2) were developed and presented as nomograms to help risk evaluation of distal SINE. The performance of the proposed predictive models was evaluated and internal validation was conducted.

RESULTS

Machine-selected variables for PM-1 included key pre-TEVAR parameters, and those for PM-2 included key virtual post-TEVAR parameters. Both models showed good calibration in both development and validation subsamples, while PM-2 outperformed PM-1. The discrimination of PM-2 was better than PM-1 in the development subsample, with an optimism-corrected area under the curve (AUC) of 0.95 and 0.77, respectively. Application of PM-2 in the validation subsample presented good discrimination with an AUC of 0.9727. The decision curve demonstrated that PM-2 was clinically useful.

CONCLUSION

This study proposed a predictive model for distal SINE incorporating the CT-based VSA. This predictive model could efficiently predict the risk of distal SINE and thus might contribute to personalized intervention planning.

CLINICAL RELEVANCE STATEMENT

This study established a predictive model to evaluate the risk of distal SINE based on the pre-stenting CT dataset and planned device information. With an accurate VSA tool, the predictive model could help to improve the safety of the endovascular repair procedure.

KEY POINTS

• Clinically useful prediction models for distal stent-induced new entry are still lacking, and the safety of the stent implantation is hard to guarantee. • Our proposed predictive tool based on a virtual stenting algorithm supports different stenting planning rehearsals and real-time risk evaluation, guiding clinicians to optimize the presurgical plan when necessary. • The established prediction model provides accurate risk evaluation for vessel damage, improving the safety of the intervention procedure.

Complications in Patients with Chronic Type B Aortic Dissection (cTBAD)-A Long-Term Analysis

Chronic type B aortic dissection (cTBAD) is a rare but challenging condition that requires individual treatment strategies. Especially the long-term therapy impacts prognosis. In this single-center retrospective study, we evaluated patients with cTBAD in our vascular outpatient clinic over 10 years. Follow-up consultations included contrast-enhanced, electrocardiogram-triggered, high-resolution CT angiography (CTA) covering the entire aorta. Evaluated characteristics went beyond demographic characteristics combining the treatment approach and the timing and occurrence of potential complications. We analyzed 133 patients in total (n = 92, 69.2% male) with cTBAD with a mean follow-up of 67.7 months. Most of them underwent invasive treatment (n = 102, 76.7%), the majority received thoracic endovascular aortic repair (TEVAR) (n = 82, 61.7%). A total of 80 patients (60.2%) had major complications, whereas over a third was free of complications even after 5 years. Most common complications were progress of dissection and endoleaks, aneurysms of true (TL) and false lumen (FL) were more common in the later time periods. The treatment of cTBAD in terms of timing, therapy approach, and complications is still challenging for the entire aortic team. Nevertheless, the early recognition of complications permits promising treatment options and highlights the importance of frequent follow-up examinations especially within the first years.

The loss of helical flow in the thoracic aorta might be an identifying marker for the risk of acute type B aortic dissection

BACKGROUND AND OBJECTIVE

The occurrence of acute type B aortic dissection (TBAD) remained unclear. This study aimed to investigate the association between flow features and hemodynamic parameters in aortas that demonstrated the risk of TBAD occurrence.

METHODS

The geometries of 15 hyperacute TBAD and 12 control patients (with healthy aorta) were reconstructed from computed tomography angiography images. Pre-TBAD models were then obtained by eliminating the dissection flaps. Flow features and hemodynamic parameters, including wall shear stress-related parameters and helicities, were compared between pre-TBAD and control models using computational fluid dynamics.

RESULTS

There were no significant differences in baseline characteristics and anatomical parameters between the two groups. Significant contralateral helical blood flow was present in the healthy thoracic aorta, while almost no helical flow was observed in the pre-TBAD group. In addition, the mean normal transverse wall shear stress (NtransWSS) was significantly higher in the pre-TBAD group (aortic arch 0.49±0.09 vs. 0.40±0.05, P = 0.04; descending aorta: 0.46±0.05 vs. 0.33±0.02, P<0.01). Moreover, a significantly negative correlation was found between helicity and NtransWSS in the descending aorta. Moreover, the location of primary tears in 12 pre-TABD subjects matched well with regions of high NtransWSS.

CONCLUSIONS

Loss of helical flow in the aortic arch and descending aorta may be a major flow feature in patients with underlying TBAD, resulting in increased flow disturbance and wall lesions.

Rapid Morphological Measurement Method of Aortic Dissection Stent Based on Spatial Observation Point Set

OBJECTIVES

Post-operative stent morphology of aortic dissection patients is important for performing clinical diagnosis and prognostic assessment. However, stent morphologies still need to be manually measured, which is a process prone to errors, high time consumption and difficulty in exploiting inter-data associations. Herein, we propose a method based on the stepwise combination of basic, non-divisible data sets to quickly obtain morphological parameters with high accuracy.

METHODS

We performed the 3D reconstruction of 109 post-operative follow-up CT image data from 26 patients using mimics software. By extracting the spatial locations of the basic morphological observation points on the stent, we defined a basic and non-reducible set of observation points. Further, we implemented a fully automatic stent segmentation and an observation point extraction algorithm. We analyzed the stability and accuracy of the algorithms on a test set containing 8 cases and 408 points. Based on this dataset, we calculated three morphological parameters of different complexity for the different spatial structural features exhibited by the stent. Finally, we compared the two measurement schemes in four aspects: data variability, data stability, statistical process complexity and algorithmic error.

RESULTS

The statistical results of the two methods on two low-complexity morphological parameters (spatial position of stent end and vascular stent end-slip volume) show good agreement (n = 26, P₁, P₂ < 0.001, r₁ = 0.992, r₂ = 0.988). The statistics of the proposed method for the morphological parameters of medium complexity (proximal support ring feature diameter and distal support ring feature diameter) avoid the errors caused by manual extraction, and the magnitude of this correction to the traditional method does not exceed 4 mm with an average correction of 1.38 mm. Meanwhile, our proposed automatic observation point extraction method has only 2.2% error rate on the test set, and the average spatial distance from the manually marked observation points is 0.73 mm. Thus, the proposed method is able to rapidly and accurately measure the stent circumferential deflection angle, which is highly complex and cannot be measured using traditional methods.

CONCLUSIONS

The proposed method can significantly reduce the statistical observation time and information processing cost compared to the traditional morphological observation methods. Moreover, when new morphological parameters are required, one can quickly and accurately obtain the target parameters by new "combinatorial functions." Iterative modification of the data set itself is avoided.

Frozen Elephant Trunk Procedure and Risk for Distal Stent-Graft-Induced New Entries

The frozen elephant trunk (FET) procedure is known as an effective treatment option for patients with any aortic pathology involving the aortic arch. However, there is growing evidence that many patients often require secondary intended, expected, or unexpected aortic reinterventions during follow-up. In those with underlying aortic dissection pathology, a substantial risk for developing distal stent-graft-induced new entries (dSINEs) has been identified as one cause for secondary aortic reinterventions. dSINE can develop at any time after the FET procedure. Endovascular treatment is generally feasible and safe to close the newly formed entry with low procedural risk. Nevertheless, all patients need continuous follow-up after FET treatment, ideally in a specialized aortic outpatient clinic.

Longitudinal morphological changes of the aorta and the endograft position before and after distal stent graft-induced new entry in aortic dissections

OBJECTIVES

The aim of this study was to assess the endograft position and aortic geometry changes after thoracic endovascular aortic repair (TEVAR) and frozen elephant trunk (FET) in distal stent-induced new entry (dSINE) patients.

METHODS

In this retrospective cohort study, the baseline demographic and the follow-up data were extracted from the hospital records, and computed tomography scans of dSINE patients after TEVAR or FET between 2011 and 2021 were analysed regarding endograft oversizing, length and migration, taper ratio, aortic diameter at the endograft end, aortic elongation (thoracic inner and outer curvature), wedge apposition angle and tortuosity angle in the distal landing zone.

RESULTS

dSINE was found in 22/213 (10%) of TEVAR and 10/31 (32%) of FET patients. The total follow-up time was 45 (27; 59) months. TEVAR was mainly performed with Relay NBS endograft (77%) and FET with Evita open prosthesis (80%). Paraplegia and stroke rates were 3%. dSINE occurred 17 (7; 35) months post-TEVAR and was instantly treated in 18 patients (56%) or followed up for 21 (11; 34) months (n = 14). Migration [+5 mm (1; 11; P < 0.001)], birdbeak angle [+9° (0; 27; P = 0.039)] and aortic diameter +5 mm (1; 11; P < 0.001) increased after dSINE, whereas aortic elongation increased already before [+12 mm (0; 27; P = 0.015)] and peaked after dSINE [+30 mm (9; 38; P < 0.001)]. The aortic elongation was more pronounced in the outer aortic curvature before and after dSINE (before: P = 0.039, after: P = 0.024). Postoperative wedge apposition [17° (12; 20)] increased before dSINE [21° (16; 35; P < 0.001)] and peaked thereafter [31° (21; 40; P < 0.001)].

CONCLUSIONS

Aortic elongation may influence the endograft position and provoke TEVAR failure in the distal and proximal landing zones.

Successive surgical repair of a progressive aortic dissection in a case of Loeys-Dietz Syndrome

INTRODUCTION

The Frozen Elephant Trunk technique is a well-established treatment for aortic dissections (Stanford Type A) involving the aortic arch and descending aorta. The Thoraflex™ Hybrid prosthesis (Vascutek Ltd.), consisting of a proximal flexible conduit and a distal self-expanding covered stent, has consistently shown positive results in the treatment of this condition.

CASE DESCRIPTION

The following is a description of such a staged reconstruction using the Thoraflex™ Hybrid Ante-Flo™ device, performed in a patient previously diagnosed with Loeys-Dietz Syndrome. After clamping the aorta proximally, an incision was taken at the distal end of the stent. Here, the distal end of the new prosthesis was inserted into the true lumen of the descending aorta and the stent was deployed. Following this, a bypass was established via the left atrium, and blood was returned to the lower body using the perfusion arm of the prosthesis with the proximal part of the descending aorta clamped. The collar of the prosthesis was sutured proximally to the aorta near the inlying previous stent. Air was removed via the perfusion arm of the prosthesis, which was then oversewn.

DISCUSSION

To date, hybrid prostheses have only been used on the proximal aorta in patients with aortic aneurysms and aortic dissections (Stanford Type A).

CONCLUSION

Using the described technique, it is possible to reconstruct the aortic anatomy using the available prostheses with accuracy and minimal complications.

Aortic remodeling, distal stent-graft induced new entry and endoleak following frozen elephant trunk: A systematic review and meta-analysis

BACKGROUND

The introduction of the frozen elephant trunk (FET) technique for total arch replacement (TAR) has revolutionized the field of aortovascular surgery. However, although FET yields excellent results, the risk of certain complications requiring secondary intervention remains present, negating its one-step hybrid advantage over conventional techniques. This systematic review and meta-analysis sought to evaluate controversies regarding the incidence of FET-related complications, with a focus on aortic remodeling, distal stent-graft induced new entry (dSINE) and endoleak, in patients with type A aortic dissection (TAAD) and/or thoracic aortic aneurysm.

MATERIALS AND METHODS

A comprehensive literature search was conducted using multiple electronic databases including EMBASE, Scopus, and PubMed/MEDLINE to identify evidence on TAR with FET in patients with TAAD and/or aneurysm. Studies published up until January 2022 were included, and after applying exclusion criteria, a total of 43 studies were extracted.

RESULTS

A total of 5068 patients who underwent FET procedure were included. The pooled estimates of dSINE and endoleak were 2% (95% confidence interval [CI] 0.01-0.06, I²  = 78%) and 3% (95% CI 0.01-0.11, I²  = 89%), respectively. The pooled rate of secondary thoracic endovascular aortic repair (TEVAR) post-FET was 7% (95% CI 0.05-0.12, I²  = 89%) while the pooled rate of false lumen thrombosis at the level of stent-graft was 91% (95% CI 0.75-0.97, I²  = 92%). After subgroup analysis, heterogeneity for distal stent-graft induced new entry (dSINE) and endoleak resolved among European patients, where Thoraflex Hybrid (THP) and E-Vita stent-grafts were used (both I²  = 0%). In addition, heterogeneity for secondary TEVAR after FET resolved among Asians receiving Cronus (I²  = 15.1%) and Frozenix stent-grafts (I²  = 1%).

CONCLUSION

Our results showed that the FET procedure in patients with TAAD and/or aneurysm is associated with excellent results, with a particularly low incidence of dSINE and endoleak as well as highly favorable aortic remodeling. However the type of stent-graft and the study location were sources of heterogeneity, emphasizing the need for multicenter studies directly comparing FET grafts. Finally, THP can be considered the primary FET device choice due to its superior results.

Endovascular reintervention after frozen elephant trunk: where is the evidence?

The introduction of the single-step hybrid frozen elephant trunk (FET) procedure for total arch replacement has revolutionized the field of aortovascular surgery. FET has proven to achieve excellent results in the repair of complex thoracic aorta pathologies. However, there remains a risk of reintervention post-FET for a variety of causes. This secondary intervention can either be performed endovascular, with thoracic endovascular aortic repair (TEVAR), or via open surgery. Multiple FET hybrid prosthesis are commercially available, each requiring different rates of endovascular reintervention. The current review will focus on providing an overview of the reintervention rates for main causes in relation to the FET grafts on the market. In addition, strategies to prevent reintervention will be highlighted. A comprehensive literature search was conducted on multiple electronic databases including PubMed, Ovid, Scopus and Embase to highlight the evidence in the literature on endovascular reintervention after FET. The main causes for secondary intervention are distal stent graft-induced new entry (dSINE), endoleak and negative aortic remodeling, and to a much lesser extent, graft kinking and aorto-esophageal fistulae. In addition, it is clear that the Thoraflex Hybrid (Terumo Aortic, Inchinnan, UK) is the superior FET device, showing excellent reintervention rates for all the above causes. Interestingly, the choice of FET device as well as its size and length can help prevent the need for reintervention. The FET procedure is indeed associated with excellent clinical outcomes, however, the need for reintervention may still arise. Importantly, the Thoraflex Hybrid prosthesis has shown excellent results when it comes to endovascular reintervention. Finally, several strategies exist that can prevent reintervention.

Incidence of Distal Stent Graft Induced New Entry vs. Aortic Remodeling Associated With Frozen Elephant Trunk

Background

The introduction of the frozen elephant trunk (FET) technique for total arch replacement (TAR) has revolutionized the field of aortivascular surgery by allowing hybrid repair of complex aortic pathologies in a single step through combining an open surgical approach with an endovascular one. FET has been associated with favorable aortic remodeling, however, its is also associated with development of distal stent graft induced new entry (dSINE) tears postoperatively. The rate of aortic remodeling and the incidence of dSINE have been linked together, in addition, there seems to be a relationship between these two variables and FET insetion length as well as graft size.

Aims

The scope of this review is to highlight the rate of aortic remodeling as well the incidence of dSINE associated with different FET devices available commercially. This review also aimed to investigate the relationship between aortic remodeling, dSINE, FET insertion length and FET graft size.

Methods

We conducted a comprehensive literature search using multiple electronic databases including PubMed, Ovid, Scopus and Embase in order to collate all research evidence on the above mentioned variables.

Results

Thoraflex™ Hybrid Plexus seems to yield optimum aortic remodeling by promoting maximum false thrombosis as well true lumen expansion. Thoraflex Hybrid™ is also associated with the lowest incidence of dSINE post-FET relative to the other FET devices on the market. Aortic remodeling and dSINE do influence each other and are both linked with FET graft length and size.

Conclusion

The FET technique for TAR shows excellent aortic remodeling but is associated with a considerable risk of dSINE development. However, Thoraflex™ Hybrid has demonstrated itself to be the superior FET device on the aortic arch prostheses market. Since aortic remodeling, dSINE, FET insertion length and stent graft size are all interconnect, the choice of FET device length and size must be made with great care for optimum results.

Mid- and long-term outcomes of thoracic endovascular aortic repair in acute and subacute uncomplicated type B aortic dissection

BACKGROUND

Uncomplicated type B aortic dissection (un-TBAD) has been managed conservatively with medical therapy to control the heart rate and blood pressure to limit disease progression, in addition to radiological follow-up. However, several trials and observational studies have investigated the use of thoracic endovascular aortic repair (TEVAR) in un-TBAD and suggested that TEVAR provides a survival benefit over medical therapy. Outcomes of TEVAR have also been linked with the timing of intervention.

AIMS

The scope of this review is to collate and summarize all the evidence in the literature on the mid- and long-term outcomes of TEVAR in un-TBAD, confirming its superiority. We also aimed to investigate the relationship between the timing of TEVAR intervention and results.

METHODS

We carried out a comprehensive literature search on multiple electronic databases including PubMed, Scopus, and EMBASE to collate and summarize all research evidence on the mid- and long-term outcomes of TEVAR in un-TBAD, as well as its relationship with intervention timing.

RESULTS

TEVAR has proven to be a safe and effective tool in un-TBAD, offering superior mid- and long-term outcomes including all-cause and aorta-related mortality, aortic-specific adverse events, aortic remodeling, and need for reintervention. Additionally, performing TEVAR during the subacute phase of dissection seems to yield optimal results.

CONCLUSION

The evidence demonstrating a survival advantage in favor TEVAR over medical therapy in un-TBAD means that with further research, particular trials and observational studies, TEVAR could become the gold-standard treatment option for un-TBAD patients.

A New Era of Diagnosis and Therapy in Acute Aortic Syndromes: The Mainz-Essen Experience (Part II)-Management and Outcomes

Over the years, the cardiovascular department of Johannes Gutenberg University in Mainz-West-German Heart Centre in Essen (Germany) designed and implemented the hybrid operating room (2003) along with advanced endovascular and surgical procedures, including the frozen elephant trunk technique. For the study purpose, the Mainz-Essen experience on acute aortic syndromes was summarized by considering original articles from single-center or multicenter studies performed at West German Heart Centre, Essen, Germany, or at the cardiovascular department of Johannes Gutenberg University, Mainz, Germany. We present the 35-year-long Mainz-Essen research, education, and patient management journey in creating an integrated multidisciplinary "Aortic Center" in the heart of Europe.

Early experience with a novel dissection-specific stent-graft to prevent distal stent-graft-induced new entry tears after thoracic endovascular repair of chronic type B aortic dissections

PURPOSE

The aim was to report short and mid-term outcomes of a novel, investigational, dissection-specific stent-graft (DSSG), specifically designed to address the features of chronic type B aortic dissection (CTBAD) and reduce the risk of distal stent-graft-induced new entry tears (dSINE).

MATERIALS AND METHODS

A retrospective single center cohort study of all patients undergoing TEVAR with the DSSG for CTBAD from January 1, 2017 to January 31, 2020. The DSSG, which is a modified stent-graft based on the Cook Zenith Alpha Thoracic platform, has no proximal barbs and a customized longer body length with substantial taper. The second and third distal Z-stents are sited internally to avoid any contact of the metal skeleton with the dissection membrane and have reduced radial force, while the most distal stent was removed creating a distal 30 mm unsupported Dacron graft.

RESULTS

Sixteen patients (13 males, 3 females) with a median age of 66 years (range 31-79 years) underwent elective TEVAR of CTBAD using the DSSG. Six patients (38%) had an underlying connective tissue disorder. The median tapering was 10mm (range 4mm-21mm) and median length 270mm (range 210-380 mm). Technical success was achieved in all but one case (96%). One patient died within 30 days, due to retrograde type A dissection with cardiac tamponade. The 30-day rate of stroke, spinal cord ischemia and re-interventions was 0%. After median imaging follow-up time of 17 months (range 1 - 31 months), one patient developed a dSINE four months after the index procedure. After median survival follow-up of 23 months (range 2 - 35 months), one late death occurred due to traumatic brain injury, while no aortic-related death occurred during follow-up. Complete false lumen (FL) thrombosis was achieved in nine patients while the remaining six showed partial FL thrombosis. No instances of diameter increase at the level of treated aortic segment were noted with serial measurements showing either stable (n=7) or decreased (n=8) maximal transverse diameter.

CONCLUSIONS

Use of a novel DSSG with low radial force for TEVAR in the setting of CTBAD is safe and feasible. This early real-world experience shows promising mid-term effectiveness with low rates of dSINE or unplanned re-interventions and satisfactory aortic remodelling during follow-up. Longer follow-up is needed, however, before any firm conclusions can be drawn.

Computational Investigation and Histopathological Validation of Interaction Between Stent Graft and Aorta in Retrograde Type A Dissection After TEVAR in Canine Models

PURPOSE

Retrograde type A dissection (RTAD) after thoracic endovascular aortic repair (TEVAR) has been a major drawback of endovascular treatment. To our knowledge, no studies have simulated and validated aortic injuries caused by stent grafts (SGs) in animal models. Therefore, the aim of this study was to evaluate and quantify the SG-aorta interaction through computational simulations and to investigate the underlying mechanism through histopathological examinations.

METHODS

Two custom-made Fabulous^® (DiNovA Meditech, Hang Zhou, China) SGs were implanted in 2 canine aortas with a 5-mm difference in the distance in landing locations. The aortic geometries were extracted from RTAD and non-RTAD cases. A computational SG model was assembled based on the implanted SG using the software Pro-ENGINEER Wildfire 5.0 (PTC Corporation, Needham, Mass). TEVAR simulations were performed 7 times for each canine model using Abaqus software (Providence, RI, USA), and the maximum aortic stress (MAS) was calculated and compared among the groups. Three months after SG implantation, the canine aortas were harvested, and were examined using hematoxylin and eosin staining and Elastica Van Gieson (EVG) staining to evaluate histopathological changes.

RESULTS

In the computational models for both canines, MAS was observed at the proximal bare stent (PBS) at aortic greater curve. The PBS generated higher stress toward the aortic wall than other SG parts did. Moreover, the MAS was significantly higher in canine No.1 than in canine No.2 (0.415±0.210 versus 0.200±0.160 MPa) (p<0.01). Notably, in canine No.1, an RTAD developed at the MAS segment, and histopathological examinations of the segment showed an intimal flap, a false lumen, elastin changes, and medial necrosis. RTAD was not observed in canine No.2. In both SG-covered aortas, medial necrosis, elastic fiber stretching, and inflammatory infiltration were seen.

CONCLUSION

The characteristic MAS distribution remained at the location where the apex of the PBS interacted with the aortic wall at greater curve. RTAD histopathological examinations showed intimal damage and medial necrosis at the proximal landing zone, at the same MAS location in computational simulations. The in vivo results were consistent with the computational simulations, suggesting the MAS at greater curve may cause RTAD, and the potential application of computational simulation in the mechanism study of RTAD.

Changes of stent-graft orientation after frozen elephant trunk treatment in aortic dissection

OBJECTIVES

Our goal was to evaluate the extent of stent-graft (SG) elastic recoil in the descending aorta after the frozen elephant trunk procedure in acute (AAD) and chronic (CAD) aortic dissection as well as the impact of SG movement on distal stent graft-induced new entry (d-SINE).

METHODS

We retrospectively analysed 149 (105 AAD, 44 CAD) of 259 aortic dissection patients after the frozen elephant trunk procedure between January 2005 and April 2019. Inclusion criteria were at least 1-year computed tomography angiography (CTA) aortic examinations during a follow-up time of 3.8 ± 2.7 years and absence of open or endovascular reintervention. Multiplanar reconstruction of CTA scans was used to define the SG vector position and movement in a virtual Cartesian coordinate system. The angle φ of vector movement and changes of aortic areas at the distal landing zone were analysed.

RESULTS

The distal SG position changed over time in the cranial (10.06 ± 11.12 mm), dorsal (8.45 ± 11.12 mm) and lateral (4.96 ± 9.89 mm) directions (P < 0.001). The total change of φ (4.08 ± 7.03°) was greater in AAD than in CAD (P = 0.026). d-SINE was more common in CAD (P < 0.001) and was associated with the size of the aortic area, aortic area enlargement and continuous SG unfolding (P < 0.001).

CONCLUSIONS

With the frozen elephant trunk technique, movement and change of SG orientation in the descending aorta were observed over time. Elastic recoil was greater in AAD than in CAD. The incidence of d-SINE was particularly dependent on the size of the aortic lumen and SG radial expansion and less on elastic recoil.

Intraoperative Stent-Graft-Induced Aortic Intimal Intussusception During TEVAR for Type B Aortic Dissection

BACKGROUND

Aortic intimal intussusception is well described in the natural progression of type A aortic dissection. Only 3 cases of aortic intimal intussusception were reported to be related to thoracic endovascular aortic repair (TEVAR) for Stanford type B aortic dissection. In our study, we are reporting a rare but potentially fatal complication, the intraoperative stent-graft (SG)-induced aortic intimal intussusception (ISAII); this study reports a series of endovascular repair for ISAII cases. By presenting the ISAII definition, the diagnostic steps to rule out or to identify the condition, and the techniques to resolve it, we intended to raise the awareness of this severe complication, so that physicians can adapt to overcome the complications while performing TEVAR.

MATERIALS AND METHODS

ISAII was defined as the partial or circumferential disruption of the distal intimal flap as an intraoperative complication of endovascular treatment. From January 2014 to June 2020, 1,096 patients underwent TEVAR for Stanford type B aortic dissection at our hospital. Among them, 14 ISAII complications were witnessed. All these patients underwent endovascular repair for ISAII lesions, and their data were extracted for analysis.

RESULTS

The ISAII lesions were classified into 3 types according to their location in different aortic segments: type I, ISAII was limited within the intended SG coverage segment; type II, ISAII occurred after SG introduction or deployment, and the detached intimal flap extended beyond the intended SG coverage segment but did not affect the abdominal aortic visceral branches; type III, ISAII occurred during SG introduction or deployment, and the detached intimal flap descended to the abdominal aortic segment with visceral branches. Our results showed ISAII as a rare complication with an incidence of 1.28% (14/1096), and endovascular repair for all types of ISAII is an effective treatment. With a mean follow-up of 27.36 months (range 5-71 months), all the ISAII lesions were stable, and all the major aortic branches, SGs, and bare stents were patent.

CONCLUSIONS

The management of this potentially devastating intraoperative complication relies on accurate diagnosis and prompt management. Our results suggested that endovascular repair for ISAII is effective and durable for correcting this complication.

GRAPHICAL ABSTRACT

[Formula: see text].

Effect of Vessel Tortuosity on Stress Concentration at the Distal Stent-Vessel Interface: Possible Link With New Entry Formation Through Biomechanical Simulation

A computational approach is used to investigate potential risk factors for distal stent graft-induced new entry (dSINE) in aortic dissection (AD) patients. Patient-specific simulations were performed based on computed tomography images acquired from six AD patients (three dSINE and three non-dSINE) to analyze the correlation between anatomical characteristics and stress/strain distributions. Sensitivity analysis was carried out using idealized models to independently assess the effect of stent graft length, stent tortuosity and wedge apposition angle at the landing zone on key biomechanical variables. Mismatch of biomechanical properties between the stented and nonstented regions led to high stress at the distal stent graft-vessel interface in all patients, as well as shear strain in the neighboring region, which coincides with the location of tear formation. Stress was observed to increase with the increase of stent tortuosity (from 263 kPa at a tortuosity angle of 50 deg to 313 kPa at 30 deg). It was further amplified by stent graft landing at the inflection point of a curve. Malapposition of the stent graft led to an asymmetrical segment within the aorta, therefore changing the location and magnitude of the maximum von Mises stress substantially (up to +25.9% with a +25 deg change in the distal wedge apposition angle). In conclusion, stent tortuosity and wedge apposition angle serve as important risk predictors for dSINE formation in AD patients.

Flow density of computed tomography aortography for predicting early unfavorable aortic remodeling after TEVAR in type IIIb aortic dissection

OBJECTIVE

Patients diagnosed of DeBakey type III aortic dissection with partial thrombosis of false lumen (FL) have a higher mortality rate. However, IIIb dissections with full patent FL tend to exhibit a partially thrombosed FL quickly after thoracic endovascular aortic repair (TEVAR); thus, we investigated survival and aortic remodeling in this population.

METHODS

We reviewed computed tomography aortograms (CTAs) of 123 patients with TEVAR-treated IIIb aortic dissections from July 2006 to June 2015; contrast density of CTAs represented intraluminal flow. Patients were selected to fit in 2 groups of FL in term of FL contrast density: low flow (LF) group (non-opacification in the midway of FL) and high flow (HF) group (full patent FL).

RESULTS

Surgical mortality was 10.3% in the HF group and 4.5% in the LF group (n = 61; LF = 22; HF = 39). 3 patients in the HF group suffered from lethal aortic rupture in 10 days postoperatively. The HF group showed significant increase in maximal diameter, and had larger thoracic (+4.00 ± 2.68 vs -1.16 ± 3.42 mm, P < .001) aortic diameter expansion from preoperation to one week postoperation. Both groups exhibited significant favorable thoracic TL expansion and maximal aortic diameter shrinkage in postoperative one week to one year. However, HF group displayed less thoracic aortic FL regression (-70.9 ± 83.5 vs -113.9 ± 95.0 cm³, P = .1) and TL expansion (+14.5 ± 27.2 vs +36.8 ± 28.3 cm³, P = .008) when compared to LF group.

CONCLUSIONS

Preoperative HF in the FL has an unfavorable effect on thoracic aortic diameter in one week post-TEVAR. This might increase the risk of aortic rupture.

[Quo vadimus? Fundamental problems of developing hybrid prostheses of thoracic aorta]

This article is a review briefly characterizing the state of the art of hybrid surgery of the thoracic aorta using the frozen elephant trunk technique worldwide and in Russia, also discussing unsolved problems of fundamental science, being key issues in creation of new models of hybrid prostheses of the thoracic aorta. The main attention is paid to the problem of radial stiffness of the stent-graft portion of the prosthesis. Performed is a detailed analysis of the factors influencing this characteristic of the sent graft: shape, size and number of cells of the stent element, thickness of the nitinol wire it is made of, method of edge connection, nitinol properties depending on the alloy grade and methods of thermoforming. It is shown that excessive stiffness leads to the development of d-SINE syndrome. This is followed by discussing the problem of optimal stiffness of stent grafts, based on the design of stent graft elements and elastic properties of the wall of the true channel of a dissecting aortic aneurysm. Also proposed is an approach to solving the problem of d-SINE, consisting in creation of conical stent grafts and/or a gradual decrease of radial stiffness of stent elements in the direction of the distal portion. Comprehensively addressed are disadvantages of the graft portion of the prosthesis, in 95% of items made of polyethylene terephthalate fiber: susceptibility to degradation associated with manufacturing defects and intraoperative microdamages, abrasive effect in the zone of contact with stent elements, partial postoperative hydrolysis and an inflammatory reaction to a foreign body, often being clinically pronounced. Also touched upon are certain aspects of creating hermetic coatings of the graft portion, with the use of vancomycin possessing low cytotoxicity as part of an antibacterial component being promising. As a whole, it is demonstrated that advances in creating a novel generation of hybrid prostheses should be associated with new approaches and materials, to be obtained at the junction of medicine and fundamental sciences.

Relevance of Aortic Dissection Chronicity to the Development of Stent Graft-induced New Entry

BACKGROUND

The relevance of aortic dissection chronicity to the development of stent graft-induced new entry (SINE) is unknown.

METHODS

This study enrolled 69 patients who underwent thoracic endovascular aortic repair (TEVAR) for chronic aortic dissection from January 2006 to December 2017 and were followed up for ≥6 months. Their medical records were reviewed retrospectively. Patients were stratified according to TEVAR timing into an early group (≤6 months from the onset of aortic dissection) and a late group (>6 months after the onset). The incidence of SINE as well as the interval between TEVAR and the development of SINE was compared between these groups.

RESULTS

During the follow-up period, SINE occurred in 12% (3/26) and 35% (15/43) of patients in the early and late groups, respectively (P = .029). The interval between TEVAR and SINE development was significantly longer in the late group than the early group (median, 92 days vs 1144 days, respectively; P = .002). According to the multivariate analysis results, the late group (hazard ratio, 3.667; 95% confidence interval, 1.037-12.968; P = .044) and the distal oversizing ratio (hazard ratio, 1.492; 95% confidence interval, 1.071-2.080; P = .018) were the independent predictors for SINE development.

CONCLUSIONS

TEVAR should be performed in the early period of the chronic phase to prevent SINE. Close and lifelong follow-up is mandatory for patients who undergo TEVAR >6 months after onset because SINE can develop several years after TEVAR in those patients.

Current options and recommendations for the use of thoracic endovascular aortic repair in acute and chronic thoracic aortic disease: an expert consensus document of the European Society for Cardiology (ESC) Working Group of Cardiovascular Surgery, the ESC Working Group on Aorta and Peripheral Vascular Diseases, the European Association of Percutaneous Cardiovascular Interventions (EAPCI) of the ESC and the European Association for Cardio-Thoracic Surgery (EACTS)

Since its clinical implementation in the late nineties, thoracic endovascular aortic repair (TEVAR) has become the standard treatment of several acute and chronic diseases of the thoracic aorta. While TEVAR has been embraced by many, this disruptive technology has also stimulated the continuing evolution of open surgery, which became even more important as late TEVAR failures do need open surgical correction justifying the need to unite both treatment options under one umbrella. This fact shows the importance of—in analogy to the heart team—aortic centre formation and centralization of care, which stimulates continuing development and improves outcome . The next frontier to be explored is the most proximal component of the aorta—the aortic root, in particular in acute type A aortic dissection—which remains the main challenge for the years to come. The aim of this document is to provide the reader with a synopsis of current evidence regarding the use or non-use of TEVAR in acute and chronic thoracic aortic disease, to share latest recommendations for a modified terminology and for reporting standards and finally to provide a glimpse into future developments.

An Innovative Customized Stent Graft Manufacture System Assisted by Three-Dimensional Printing Technology

BACKGROUND

Commercially available thoracic aortic stent grafts rarely match the geometric characteristics of the aorta perfectly, which can lead to complications. Customization maybe a solution for this problem, but the delay inherent in the current manufacturing process makes it unable to meet the urgent requirement of acute aortic events. We established and optimized a rapid design and manufacture system for a customized aortic stent graft assisted by 3-dimensional (3D) printing technology. We also evaluated the preliminary feasibility and capability of this customized stent graft.

METHODS

Seven essential production steps comprised the rapid design and manufacture process for the customized stent graft system assisted by 3D printing technology. Optimization of the manufacture process was refined over time in 3 stages. Bench test and in vivo experiments were used to verify the feasibility of this system and evaluate the preliminary usability of the customized stent graft.

RESULTS

After optimization, the theoretical production time of the customized stent graft was reduced to approximately 12 hours. Bench test showed radial forces against the aorta wall were better distributed in the customized stent graft than in the control stent graft. In vivo experimental results showed that the customized stent graft system worked effectively.

CONCLUSIONS

It was feasible to rapidly design and manufacture a customized aortic stent graft assisted by 3D printing technology, which demonstrated better geometric compliance and physical characters in the bench test and in in vivo experimentation. The manufacturing process could be accelerated to approximately 12 hours, which might be optimized further to meet urgent clinic requirements.

Right size matters! The ideal size of hybrid prosthesis in frozen elephant trunk

There is abundant of literature emerging to support the use of the frozen elephant trunk prosthesis, but there is still a lack of clear consensus on the sizing of the hybrid prosthesis. There is a general consensus that the stent should not be oversized in acute aortic dissection and chronic aortic dissection. Some surgeons consider that only the true lumen has to be measured while others argue that the entire diameter of the aorta has to be measured, and a few measure the aorta intraoperatively. In regards to thoracic aortic aneurysm, most surgeons oversize the stent-graft by 10% to 20%. A small device may not provide adequate sealing, whereas a larger device may cause new entry points distally. Hence, an appropriate device has to be selected for the optimal outcome.

Geometric Analysis of Type B Aortic Dissections Shows Aortic Remodeling After Intervention Using Multilayer Stents

Recently, multilayer stents for type B aortic dissections (TBAD) have been proposed to decrease false lumen flow, increase and streamline true lumen flow, and retain branch vessel patency. We aimed to provide a protocol with standardized techniques to investigate aortic remodeling of TBAD by multilayer flow modulators (MFM) in static geometric and hemodynamic analyses. Combining existing literature and new insights, a standardized protocol was designed. Using pre- and postoperative CT scans, geometric models were constructed, lumen dimensions were calculated, computational fluid dynamics (CFD) models were composed, and velocity and pressures were calculated. Sixteen TBAD cases treated with MFM were included for analysis. For each case, aortic remodeling was analyzed using post-processing medical imaging software. After 3D models were created, geometrical anatomical measurements were performed, and meshes for finite element analysis were generated. MFM cases were compared pre- and postoperatively; true lumen volumes increased (p < 0.001), false lumen volumes decreased (p = 0.001), true lumen diameter at the plane of maximum compression (PMC) increased (p < 0.001), and false lumen index decreased (p = 0.008). True lumen flow was streamlined, and the overall fluid velocity and pressures decreased (p < 0.001 and p = 0.006, respectively). This protocol provided a standardized method to evaluate the effects of MFM treatments in TBAD on geometric analyses, PMC, and CFD outcomes.

Distal Stent Graft-Induced New Entry After TEVAR or FET: Insights Into a New Disease From EuREC

BACKGROUND

The study sought to learn about incidence and reasons for distal stent graft-induced new entry (dSINE) after thoracic endovascular aortic repair (TEVAR) or after frozen elephant trunk (FET) implantation, and develop prevention algorithms.

METHODS

In an analysis of an international multicenter registry (EuREC [European Registry of Endovascular Aortic Repair Complications] registry), we found 69 dSINE patients of 1430 (4.8%) TEVAR patients with type B aortic dissection and 6 dSINE patients of 100 (6%) patients after the FET procedure for aortic dissection with secondary morphological comparison.

RESULTS

The underlying aortic pathology was acute type B aortic dissection in 33 (44%) patients, subacute or chronic type B aortic dissection in 34 (45%) patients, acute type A aortic dissection in 3 patients and remaining dissection after type A repair in 3 (8%) patients, and acute type B intramural hematoma in 2 (3%) patients. dSINE occurred in 4.4% of patients in the acute setting and in 4.9% of patients in the subacute or chronic setting after TEVAR. After the FET procedure, dSINE occurred in 5.3% of patients in the acute setting and in 6.5% of patients in the chronic setting. The interval between TEVAR or FET and the diagnosis of dSINE was 489 ± 681 days. Follow-up after dSINE was 1340 ± 1151 days, and 4 (5%) patients developed recurrence of dSINE. Morphological analysis between patients after TEVAR with and without dSINE showed a smaller true lumen diameter, a more accentuated oval true lumen morphology, and a higher degree of stent graft oversizing in patients who developed dSINE.

CONCLUSIONS

dSINE after TEVAR or FET is not rare and occurs with similar incidence after acute and chronic aortic dissection (early and late). Avoiding oversizing in the acute and chronic settings as well as carefully selecting patients for TEVAR in postdissection aneurysmal formation will aid in reducing the incidence of dSINE to a minimum.

Design of non-equal-strut stent hoops for structural optimization of thoracic aortic stent-grafts

Background: Endovascular aortic aneurysm repair (EVAR) with stent-grafts is used widely for the treatment of thoracic aortic aneurysms (TAA). Inappropriate design of stent-grafts may lead to complications such as endoleak, stent-graft migration and new entries, causes of which may be inappropriate radial support force or insufficient longitudinal flexibility of the stent-grafts.Material and methods: To improve the mechanical performance of the stent-grafts, a type of non-equal-strut stent hoops was proposed, and the influence of structural parameters on the mechanical performance was studied.Results: Results of numerical simulation and physical experiments show that by using the proposed non-equal-strut stent hoops, radial support force and longitudinal flexibility of stent-grafts can be reconciled and balanced.Conclusion: Results of this study could be used to facilitate radial force control and longitudinal flexibility enhancement in the design of aortic stent-grafts.

Society for Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) Reporting Standards for Type B Aortic Dissections

This Society for Vascular Surgery/Society of Thoracic Surgeons (SVS/STS) document illustrates and defines the overall nomenclature associated with type B aortic dissection. The contents describe a new classification system for practical use and reporting that includes the aortic arch. Chronicity of aortic dissection is also defined along with nomenclature in patients with prior aortic repair and other aortic pathologic processes, such as intramural hematoma and penetrating atherosclerotic ulcer. Complicated vs uncomplicated dissections are clearly defined with a new high-risk grouping that will undoubtedly grow in reporting and controversy. Follow-up criteria are also discussed with nomenclature for false lumen status in addition to measurement criteria and definitions of aortic remodeling. Overall, the document provides a facile framework of language that will allow more granular discussions and reporting of aortic dissection in the future.

Risk factors of distal segment aortic enlargement after complicated type B aortic dissection

Objectives

Distal segment aortic enlargement (DSAE) is a common complication that influences the long-term prognosis of type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR). In this study, a multivariate analysis was performed to find potential factors predictive of DSAE.

Methods

A single-center retrospective study was performed from 1999 to 2016. Included in the study were complicated TBAD patients who underwent TEVAR with uncovered residual tears. Based on the diameter of the distal segment of the uncovered aorta, we assigned patients to an enlargement group and a non-enlargement group. Data extracted from the medical records included demographic and clinical characteristics and follow-up computed tomography angiography data. The primary endpoints were the all-cause mortality and the presumably aortic-related events that required reintervention during the follow-up period.

Results

For the 333 patients, all-cause mortality was 38 (11.41%), and 76 (22.82%) patients underwent reintervention. A total of 70 (21.02%) patients experienced DSAE, among them were 2 patients who died of aortic rupture and 58 patients who accepted reintervention. Multivariate analysis reviewed independent risk factors of postoperative DSAE, including current smoking, the residual length of the patent false lumen, the postoperative number of dissection tears in the thoracic aorta and type III aortic arch; as well as protective factors, including the application of a restrictive bare stent (RBS), the length of covered stent in the descending thoracic aorta, and the distance from the residual first tear to the left subclavian artery (LSA).

Conclusion

DSAE after TEVAR for patients with a complicated TBAD can be influenced by their current smoking habit, the residual length of patent false lumen, the postoperative number of dissection tears in the thoracic aorta and the aortic arch type. Meanwhile, RBS usage, the length of the covered stent in the descending thoracic aorta and the distance from the residual first tear to the LSA could have positive effect on the prognosis.

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.

Consistency of Proximal-to-Distal Tapering of Descending Thoracic Aortic Diameter: Quantification Using a Novel Computer Tomography-based Assessment

BACKGROUND

Successful endovascular repair of thoracic aorta for type B aortic dissection requires correct stent-graft sizing, particularly of distal landing zone which is mainly based on operator experience. The present study aimed to quantitatively define proximal-to-distal tapering of descending thoracic aortic diameter and its consistency.

METHODS

The novel parameter HDP (Hundred times Distance accounts for Percentage)-measured as distance from the distal end of the left subclavian artery to each level along the aortic central line/length from the distal end of the left subclavian artery to the proximal end of the celiac artery along the aortic central line × 100-was calculated per 1% unit of descending thoracic aorta based on 3-mensio software-derived measurements from 281 consecutive individuals who had undergone enhanced chest computer tomography scanning. Association between HDP and maximal diameter of descending thoracic aorta was assessed by using the generalized additive mixed model with smoothing function and threshold saturation effect analyses with generalized estimating equations. Nonadjusted and adjusted models were performed to illuminate its consistency.

RESULTS

Three inflection levels (HDPs of 15.01, 36.63, and 77.74) were identified which allowed to divide the descending thoracic aorta into 4 segments. The taper was consistent before and after adjusting for age, sex, height, body mass index, hypertension, smoking habits, hyperlipidemia, and diabetes. Although 1% unit of descending thoracic aorta decreases, the maximal diameter reduces to 0.007 mm (-0.025, 0.010; P = 0.414) in the segment with HDP <15.01, to 0.151 mm (-0.158, -0.145; P < 0.001) in the segment with 15.01 ≤ HDP < 36.63, to 0.038 mm (-0.040, -0.036; P < 0.001) in the segment with 36.63 < HDP ≤ 77.74; and to 0.026 mm (-0.049, -0.002; P = 0.035) in the segment with HDP > 77.74, respectively.

CONCLUSIONS

The maximal diameter of descending thoracic aorta decreases gradually and consistently among individuals free of aortic diseases.