A geometric reappraisal of proximal landing zones for thoracic endovascular aortic repair according to aortic arch types

A computational study of artery curvature and endograft oversize influence on seal zone behavior in endovascular aortic repair

Thoracic endovascular aortic repair (TEVAR) is a minimally invasive procedure involving the placement of an endograft inside the dissection or an aneurysm to direct blood flow and prevent rupture. A significant challenge in endovascular surgery is the geometrical mismatch between the endograft and the artery, which can lead to endoleak formation, a condition where blood leaks between the endograft and the vessel wall. This study uses computational modeling to investigate the effects of artery curvature and endograft oversizing, the selection of an endograft with a larger diameter than the artery, on endoleak creation. Finite element analysis is employed to simulate the deployment of endografts in arteries with varying curvature and diameter. Numerical simulations are conducted to assess the seal zone and to quantify the potential endoleak volume as a function of curvature and oversizing. A theoretical framework is developed to explain the mechanisms of endoleak formation along with proof-of-concept experiments. Two main mechanisms of endoleak creation are identified: local buckling due to diameter mismatch and global buckling due to centerline curvature mismatch. Local buckling, characterized by excess graft material buckling and wrinkle formation, increases with higher levels of oversizing, leading to a larger potential endoleak volume. Global buckling, where the endograft bends or deforms to conform to the centerline curvature of the artery, is observed to require a certain degree of oversizing to bridge the curvature mismatch. This study highlights the importance of considering both curvature and diameter mismatch in the design and clinical use of endografts. Understanding the mechanisms of endoleak formation can provide valuable insights for optimizing endograft design and surgical planning, leading to improved clinical outcomes in endovascular aortic procedures.

Type III aortic arch angulation increases aortic stiffness: Analysis from an ex vivo porcine model

Objective

The relationship among increased aortic arch angulation, aortic flow dynamics, and vessel wall stiffness remains unclear. This experimental ex vivo study investigated how increased aortic arch angulation affects aortic stiffness and stent-graft induced aortic stiffening, assessed by pulse wave velocity (PWV).

Methods

Porcine thoracic aortas were connected to a circulatory mock loop in a Type I and Type III aortic arch configuration. Baseline characteristics and blood pressures were measured. Proximal and distal flow curves were acquired to calculate PWV in both arch configurations. After that, a thoracic stent-graft (VAMF2626C100TU) was deployed in aortas with adequate proximal landing zone diameters to reach 10% t0 20% oversizing. Acquisitions were repeated for both arch configurations after stent-graft deployment.

Results

Twenty-four aortas were harvested, surgically prepared, and mounted. Cardiac output was kept constant for both arch configurations (Type I: 4.74 ± 0.40 and Type III: 4.72 ± 0.38 L/minute; P = .703). Compared with a Type I arch, aortic PWV increased significantly in the Type III arch (3.53 ± 0.40 vs 3.83 ± 0.40 m/second; P < .001), as well as blood pressures. A stent-graft was deployed in 15 aortas. After deployment, Type I arch PWV increased (3.55 ± 0.39 vs 3.81 ± 0.44 m/second; P < .001) and Type III arch PWV increased although not significantly (3.86 ± 0.42 vs 4.03 ± 0.46 m/second; P = .094). Type III arch PWV resulted the highest and significantly higher compared with the Type I arch after stent-graft deployment (3.81 ± 0.44 vs 4.03 ± 0.46 m/second; P = .023).

Conclusions

Increased aortic arch angulation-as in a Type III arch-is associated with higher aortic PWV and blood pressures and this may negatively influence cardiovascular health.

Fast Approximate Quantification of Endovascular Stent Graft Displacement Forces in the Bovine Aortic Arch Variant

PURPOSE

Displacement forces (DFs) identify hostile landing zones for stent graft deployment in thoracic endovascular aortic repair (TEVAR). However, their use in TEVAR planning is hampered by the need for time-expensive computational fluid dynamics (CFD). We propose a novel fast-approximate computation of DFs merely exploiting aortic arch anatomy, as derived from the computed tomography (CT) and a measure of central aortic pressure.

MATERIALS AND METHODS

We tested the fast-approximate approach against CFD gold-standard in 34 subjects with the "bovine" aortic arch variant. For each dataset, a 3-dimensional (3D) model of the aortic arch lumen was reconstructed from computed tomography angiography and CFD then employed to compute DFs within the aortic proximal landing zones. To quantify fast-approximate DFs, the wall shear stress contribution to the DF was neglected and blood pressure space-distribution was averaged on the entire aortic wall to reliably approximate the patient-specific central blood pressure. Also, DF values were normalized on the corresponding proximal landing zone area to obtain the equivalent surface traction (EST).

RESULTS

Fast-approximate approach consistently reflected (r2=0.99, p<0.0001) the DF pattern obtained by CFD, with a -1.1% and 0.7° bias in DFs magnitude and orientation, respectively. The normalized EST progressively increased (p<0.0001) from zone 0 to zone 3 regardless of the type of arch, with proximal landing zone 3 showing significantly greater forces than zone 2 (p<0.0001). Upon DF normalization to the corresponding aortic surface, fast-approximate EST was decoupled in blood pressure and a dimensionless shape vector (S) reflecting aortic arch morphology. S showed a zone-specific pattern of orientation and proved a valid biomechanical blueprint of DF impact on the thoracic aortic wall.

CONCLUSION

Requiring only a few seconds and quantifying clinically relevant biomechanical parameters of proximal landing zones for arch TEVAR, our method suits the real preoperative decision-making process. It paves the way toward analyzing large population of patients and hence to define threshold values for a future patient-specific preoperative TEVAR planning.

Biomarkers of Spinal Cord Injury in Patients Undergoing Complex Endovascular Aortic Repair Procedures-A Narrative Review of Current Literature

Complex endovascular aortic repair (coEVAR) of thoracoabdominal aortic aneurysms (TAAA) has greatly evolved in the past decades. Despite substantial improvements of postoperative care, spinal cord injury (SCI) remains the most devastating complication of coEVAR being associated with impaired patient outcome and having an impact on long-term survival. The rising number of challenges of coEVAR, essentially associated with an extensive coverage of critical blood vessels supplying the spinal cord, resulted in the implementation of dedicated SCI prevention protocols. In addition to maintenance of adequate spinal cord perfusion pressure (SCPP), early detection of SCI plays an integral role in intra- and postoperative patient care. However, this is challenging due to difficulties with clinical neurological examinations during patient sedation in the postoperative setting. There is a rising amount of evidence, suggesting that subclinical forms of SCI might be accompanied by an elevation of biochemical markers, specific to neuronal tissue damage. Addressing this hypothesis, several studies have attempted to assess the potential of selected biomarkers with regard to early SCI diagnosis. In this review, we discuss biomarkers measured in patients undergoing coEVAR. Once validated in future prospective clinical studies, biomarkers of neuronal tissue damage may potentially add to the armamentarium of modalities for early SCI diagnosis and risk stratification.

Reintervention after Thoracic Endovascular Aortic Repair of Uncomplicated Type B Aortic Dissection

BACKGROUND

Data are scarce regarding the incidence, reasons, potential risk factors, and long-term outcomes of reintervention after thoracic endovascular aortic repair (TEVAR) in patients with uncomplicated type B aortic dissection (TBAD).

METHODS

Between January 2010 and December 2020, 238 patients with uncomplicated TBAD who received TEVAR were analyzed retrospectively. The clinical baseline data, aorta anatomy, dissection characteristics, and details of the TEVAR procedure were evaluated and compared. A competing-risk regression model was used to estimate the cumulative incidences of reintervention. The multivariate Cox model was used to identify the independent risk factors.

RESULTS

The mean follow-up time was 68.6 months. A total of 27 (11.3%) cases of reintervention were observed. The competing-risk analyses showed that the 1-, 3-, and 5-year cumulative incidences of reintervention were 5.07%, 7.08%, and 14.0%, respectively. Reasons for reintervention included endoleak (25.9%), aneurysmal dilation (22.2%), retrograde type A aortic dissection (18.5%), distal stent-graft-induced new entry and false lumen expansion (18.5%), and dissection progression and/or malperfusion (14.8%). Multivariable Cox analysis demonstrated that a larger initial maximal aortic diameter (Hazard ratio [HR], 1.75; 95% Confidence interval [CI], 1.13-2.69, p = 0.011) and increased proximal landing zone oversizing (HR, 1.07; 95% CI, 1.01-1.47, p = 0.033) were the significant risk factors for reintervention. Long-term survival rates were comparable between patients with or without reintervention (p = 0.915).

CONCLUSIONS

Reintervention after TEVAR in patients with uncomplicated TBAD is not uncommon. A larger initial maximal aortic diameter and excessive proximal landing zone oversizing are associated with the second intervention. Reintervention does not significantly affect long-term survival.

Patient selection and anatomical considerations for zone 0 endovascular aneurysm arch repair

Endovascular aortic arch repair has been widely used in select patients who are considered high risk for open surgical repair and have suitable anatomy. The anatomical challenges of placement of stent-grafts in the ascending aorta are many, including the curved configuration, short landing zone, proximity to the aortic valve and coronary arteries and need to incorporate the supra-aortic trunks. Stent-graft designs with fenestrations and/or directional branches are applicable to patients who have suitable landing zones in the aorta and supra-aortic trunks, adequate access and absence of significant atheromatous debris. These devices include single and multibranch concepts, which are used in combination or not with cervical debranching procedures. This article summarizes the most commonly used anatomical criterion with currently utilized arch branch stent-grafts.

Risk factors for distal stent graft-induced new entry after endovascular repair in uncomplicated type B aortic dissection

OBJECTIVE

We investigated the risk factors for distal stent graft-induced new entry (dSINE) after thoracic endovascular aortic repair for patients with uncomplicated type B aortic dissection (TBAD) and reported the outcomes of using a tapered stent graft and dSINE reintervention.

METHODS

A total of 226 patients with uncomplicated TBAD who had undergone thoracic endovascular aortic repair between January 2010 and December 2018 were analyzed retrospectively. The global features of the thoracic aorta and the local features of the proximal and distal landing zones were evaluated and compared between the dSINE and non-dSINE groups. A multivariate Cox model was used to identify the independent risk factors for dSINE. The cumulative incidence of reintervention was estimated using competing risk models.

RESULTS

After a median follow-up of 4.6 years, 16 patients (7.1%) had developed dSINE. Multivariable Cox regression analysis demonstrated that a type III aortic arch, decreased angle, increased distal oversizing, and increased distal mismatch ratio were significant risk factors for dSINE. Of the patients with tapered stent grafts, five with a ≤4-mm taper had developed dSINE. However, no dSINE was seen in the >4-mm taper group (P = .024). Reintervention was performed for 7 of the 16 patients with dSINE (43.8%). The mean time from the initial detection of dSINE to reintervention was 6.43 ± 4.62 months. The competing risk analyses showed that the cumulative incidence of reintervention in the dSINE group at 1, 3, and 5 years was 25.0%, 37.5%, and 43.5%, respectively.

CONCLUSIONS

A type III aortic arch, excessive distal oversizing and mismatch ratio, and severe angulation were associated with dSINE in patients with uncomplicated TBAD. The use of a tapered stent graft with a >4-mm taper could help prevent dSINE in patients with a high taper ratio. Aggressive reintervention was associated with favorable long-term outcomes for patients with progressive dSINE.

Single-branched stent-graft with on-table fenestration for endovascular repair of primary retrograde type A aortic dissection: A multicenter retrospective study

Objective

This study aims to evaluate the feasibility, efficacy, and safety of a single-branched stent-graft with on-table fenestration for primary retrograde type A aortic dissection (RTAD) during thoracic endovascular aortic repair (TEVAR).

Materials and methods

From January 2019 to December 2021, 36 patients with primary RTAD from five tertiary hospitals received medical management in the acute phase. They underwent TEVAR with a proximal zone 1 landing for aortic arch reconstruction in the subacute phase, using a fenestration technique on a single-branched stent-graft. Nearly 2 weeks after admission, computed tomography angiography (CTA) was re-examined to evaluate the thrombosis status of retrograde false lumen (FL). The primary outcomes were technical success, patency of the target branch arteries, and absence of type Ia endoleaks. The second outcomes were stent-graft-related complications and all-cause mortality.

Results

The mean age was 56.2 ± 11.3 years, and 29 (80.6%) were male. After a median interval of 18.0 [interquartile range (IQR), 17.0–20.3] days of medical treatment, the partial and complete thrombosis of proximal FL rates increased to 52.8% and 47.2%, respectively. One patient (2.8%) experienced postoperative type Ia endoleaks, and was successfully re-treated using coli and Onyx glue. The median hospital stay was 20.5 (IQR, 18.0–23.0) days. The overall technical success rate was 100%. The median follow-up time was 31.5 (IQR, 29.8–34.0) months. There was one death (2.8%) due to gastrointestinal bleeding. Distal aortic segmental enlargement (DASE) occurred in two (5.6%) patients. No major complications or recurrent dissections in the proximal landing zone were recorded during follow up.

Conclusion

The retrograde FL in primary RTAD could realize partial or complete thrombosis after medical management in the acute phase, and it might be regarded as a valid proximal landing zone for endovascular repair. The single-branched stent graft with on-table fenestration performed in the subacute phase may be feasible strategy in selective primary RTAD patients.

Vascular Access Challenges in Thoracic Endovascular Aortic Repair: A Literature Review

BACKGROUND

This review aims to comprehensively summarize access challenges in thoracic endovascular aortic repair (TEVAR) by describing vascular access routes, associated risks, outcomes, and complications.

METHODS

A literature search was conducted utilizing the PubMed (Medline), Scopus, and Web of Science databases. Qualitative and quantitative data from selected studies are extracted and discussed according to available standards for narrative reviews.

RESULTS

In total, there were 109 eligible studies based on predefined inclusion- and exclusion criteria. There were 39 original articles or reviews and 57 case series or case reports. This article summarizes the evidence from these studies and discusses traditional retrograde access routes and techniques for TEVAR via a femoral or iliac route, with or without the use of conduits. Next, alternative antegrade access routes and techniques via a brachial, axillary, carotid, ascending aorta, transapical, transcaval, or another route are discussed. Vascular access complications are presented with specific attention to the importance of gender and alternative antegrade access routes.

CONCLUSIONS

Multiple access routes and techniques are currently available to overcome access challenges associated with TEVAR, based on low grade evidence from heterogeneous studies. Future research that compares different access routes and techniques might help in the development of a tailored access protocol for specific patients with challenging TEVAR access.

From The RELAY® Family - A Story of Single Branched International Outcomes

BACKGROUND

Advances in surgery over the last few decades has led to the development and widespread utilisation of thoracic endovascular aortic repair (TEVAR). TEVAR, due to its minimally invasive nature and potential superior outcomes, is now becoming a key focus of interest in treating pathologies of the aortic arch, which has traditionally been treated with open surgical repair (OSR). We present our findings of our international multi-centre dataset documenting the efficacy of the single-branched RELAY™ endograft in terms of technical success, post-operative outcomes, and reintervention rates.

METHODS

Prospective data was collected and retrospectively analysed with descriptive and distributive analysis between January 2019 and January 2022 from 17 patients treated with RELAY™ single-branched endoprostheses from centres across Europe. Follow up data from 30 days and 6-, 12-, and 24 months postoperatively was included. Patient follow up was evaluated in terms of post-operative outcomes, target vessel patency and reintervention rates.

RESULTS

Technical success was achieved in all 17 patients (100%) and there were no postoperative disabling or non-disabling strokes in our single-branched RELAY™ cohort. The target vessel patency remained 100% during the first 30 days post-operatively, however, by the end of the follow-up period (24 months), target vessel patency was achieved in 93.7% of the patients. There were no reinterventions or deaths during the full study duration using the single-branched RELAY™ stent-graft.

CONCLUSION

These results with the single branched RELAY™ stent graft demonstrate favourable outcomes in comparison to the literature and demonstrate the feasibility of treatment of aortic pathology with this single-branched graft in the future. Further studies with larger patient cohorts will help us to accumulate evidence for the feasibility of the single branched RELAY™ stent graft for aortic arch surgery in the future.

Stent-Graft Migration Post-Endovascular Repair of Thoracic Aorta: A Retrospective Cohort Study

Background Migration of the stent-graft post-thoracic endovascular aortic repair (TEVAR) is not uncommon; however, it is sparsely reported. The objective of this study was to assess the incidence, risk factors, and complications of stent-graft migration post-TEVAR.

Materials and Methods Thirty-one patients who underwent TEVAR were retrospectively analyzed. The demographic, anatomical, and procedure-related factors were assessed. The measurements were done along the greater curvature of aorta around two fixed anatomic landmarks, that is, left common carotid artery or neoinnominate artery (hybrid repair) proximally and celiac artery distally. Aortic elongation and migration at proximal, distal, as well as at overlapping zone were measured. More than 10 mm of migration was considered significant.

Results Significant migration was observed in six (19%) patients. No significant migration was observed in the overlapping zone. The proximal landing zone 3 (odds ratio [OR] 12.78, p 0.01) was a significant risk factor, whereas landing zone 2 was a protective factor against the migration (OR 0.08, p 0.02). The odds for migration were more in segments I/3 and II/3 compared with I/2 and II/2, respectively, as per Modified Arch Landing Areas Nomenclature. A single complication was seen in the migration group which was treated by an overlapping stent graft.

Conclusion The stent-graft migration after TEVAR is not uncommon. Type 3 proximal landing zone was a significant risk factor for migration with an increased risk toward I/3 and II/3. Proximal landing zone 2 as well as adequate overlapping distance in multiple stent grafts can prevent migration.

Ethical Approval No IECPG-227/24.06.2020

Risk evaluation of type B aortic dissection based on WSS-based indicators distribution in different types of aortic arch

BACKGROUND AND OBJECTIVE

The underlying mechanism of aortic dissection (AD) remains unclear and the onset of AD is still unpredictable. Although clinical study with statistical analysis has reported that type III aortic arch may have strong correlation with type B AD (TBD), the effects of different arch types on the wall shear stress (WSS) have not been clarified.

METHODS

As a complementary work, this study numerically investigated the distribution of five WSS-based indicators in thirty aortic arches without AD, which were classified into three groups based on the arch types.

RESULTS

The distribution of most WSS indicators, such as time averaged WSS (TAWSS), oscillatory shear index (OSI) and relative residence time (RRT) had no significant difference among different types of aortic arches (P>0.05). However, a multidirectional WSS index, namely CFI, was found its maximum value was positively correlated with type III aortic arch in proximal descending aorta (p<0.001, r = 0.65).

CONCLUSIONS

It can be concluded that the enhancement or oscillation of WSS may not be the main reason of TBD is prevalence in type III arches, while the multidirectional WSS distribution may be an important factor. It can be further referred that the CFI may have a potential to predict the onset of TBD.

A Deep Learning-Based and Fully Automated Pipeline for Thoracic Aorta Geometric Analysis and Planning for Endovascular Repair from Computed Tomography

Feasibility assessment and planning of thoracic endovascular aortic repair (TEVAR) require computed tomography (CT)-based analysis of geometric aortic features to identify adequate landing zones (LZs) for endograft deployment. However, no consensus exists on how to take the necessary measurements from CT image data. We trained and applied a fully automated pipeline embedding a convolutional neural network (CNN), which feeds on 3D CT images to automatically segment the thoracic aorta, detects proximal landing zones (PLZs), and quantifies geometric features that are relevant for TEVAR planning. For 465 CT scans, the thoracic aorta and pulmonary arteries were manually segmented; 395 randomly selected scans with the corresponding ground truth segmentations were used to train a CNN with a 3D U-Net architecture. The remaining 70 scans were used for testing. The trained CNN was embedded within computational geometry processing pipeline which provides aortic metrics of interest for TEVAR planning. The resulting metrics included aortic arch centerline radius of curvature, proximal landing zones (PLZs) maximum diameters, angulation, and tortuosity. These parameters were statistically analyzed to compare standard arches vs. arches with a common origin of the innominate and left carotid artery (CILCA). The trained CNN yielded a mean Dice score of 0.95 and was able to generalize to 9 pathological cases of thoracic aortic aneurysm, providing accurate segmentations. CILCA arches were characterized by significantly greater angulation (p = 0.015) and tortuosity (p = 0.048) in PLZ 3 vs. standard arches. For both arch configurations, comparisons among PLZs revealed statistically significant differences in maximum zone diameters (p < 0.0001), angulation (p < 0.0001), and tortuosity (p < 0.0001). Our tool allows clinicians to obtain objective and repeatable PLZs mapping, and a range of automatically derived complex aortic metrics.

Aortic arch type, a novel morphological indicator and the risk for acute type B aortic dissection

 

OBJECTIVES

Aortic arch type is a readily recognizable and obtainable morphological feature of the aorta that does not require complex measurements. The goal of this study was to evaluate whether aortic arch type is a comparable and alternative morphological parameter for predicting acute type B aortic dissection (aTBAD) by comparing the prognostic value of the aortic arch type with that of other morphological parameters such as aortic length, angulation and tortuosity index.

METHODS

The patients with aTBAD (n = 216) were matched 1:1 with a control group (n = 263) by propensity score matching. The morphological data of the ascending aorta and the aortic arch, which included diameter, length, angulation and tortuosity index, were collected on a three-dimensional aortic model using 3mensio Vascular software. The aortic arch type was identified by the vertical distance from the origin of the brachiocephalic trunk to the top of the arch. The binary logistic regression models were analysed to determine the independent geometric variables related to the aTBAD. The nonparametric approach was performed to assess whether there were statistical differences between the area under the receiver operating characteristic curves (AUC) of the models.

RESULTS

After propensity score matching, 151 matched pairs of patients were selected. The diameters at the sinotubular junction and the mid-ascending aorta, the ascending aorta length and the ascending aorta angulation in the aTBAD group were significantly greater than those of the controls. Compared with the control group, the diameters at the proximal aortic arch, mid-aortic arch and distal aortic arch, the angulation and the tortuosity index of the aortic arch were significantly greater in the aTBAD group. The proportion of the type III arch in the patients with aTBAD is higher than that of the type I arch and the type II arch (χ² = 70.187; P < 0.001). Binary logistic regression analysis showed that the diameter at the mid-aortic arch, the ascending aorta length, the aortic arch angulation and the tortuosity index were independently related to the aTBAD with an AUC value of 0.887. Another binary logistic regression analysis indicated that the diameter at the mid-aortic arch and the aortic arch type were independent correlative variables associated with the aTBAD with an AUC of 0.874. No significant difference was observed in the prognostic value of receiver operating characteristic curves between the 2 models (P = 0.716).

CONCLUSIONS

The type III arch, which has the characteristics of aortic elongation, incremental angulation and tortuosity index, is a comparable and alternative identifier for patients at high risk for aTBAD.

Aortic Geometric Alteration Associated With Acute Type B Aortic Dissection: Angulation, Tortuosity, and Arch Type

Background: Acute type B aortic dissection is a highly serious aortic pathology. Aortic geometric parameters may be useful variables related to the occurrence of acute type B aortic dissection (aTBAD). The aim of the study is to delineate the alteration in aortic geometric parameters and analyze the specific geometric factors associated with aTBAD.

Methods: The propensity score matching method was applied to control confounding factors. The aortic diameter, length, angulation, tortuosity, and type of aortic arch of the aTBAD and control group were retrospectively analyzed via three-dimensional computed tomography imaging created by the 3mensio software (version 10.0, Maastricht, The Netherlands). The geometric variables of true lumen and false lumen in the descending aorta were measured to estimate the severity of aortic dissection. Multivariable logistic regression models were used to investigate the significant and specific factors associated with aTBAD occurrence. The area under the receiver operating characteristic curve (AUC) was used to estimate the performance of the model.

Results: After propensity score matching, 168 matched pairs of patients were selected. The ascending aorta and aortic arch diameters were dilated, and the ascending aorta and total aorta lengths were elongated in aTBAD group significantly (P < 0.001). The ascending aorta and aortic arch angulations in the aTBAD group were sharper than those of the controls (P = 0.01, P < 0.001, respectively). The aortic arch and total aorta tortuosities were significantly higher in the aTBAD group (P = 0.001, P < 0.001, respectively). There were more type III arch patients in the aTBAD group than the controls (67.9 vs. 22.6%). The true lumen angulation was sharper than that in the false lumen (P < 0.01). The true lumen tortuosity was significantly lower than that in the false lumen (P < 0.001). The multivariable models identified that aortic arch angulation, tortuosity, and type III arch were independent and specific geometric factors associated with aTBAD occurrence. The AUC of the multivariable models 1, 2, 3 were 0.945, 0.953, and 0.96, respectively.

Conclusions: The sharper angulation and higher tortuosity of aortic arch and type III arch were the geometric factors associated with aTBAD in addition to the ascending aorta elongation and aortic arch dilation. The angulation and tortuosity of the true and false lumens may carry significant clinical implications for the treatment and prognosis of aTBAD.

Morphological Features of Aortic Arch Predicting the Risk for Acute Type B Aortic Dissection

BACKGROUND

The purpose of the study is to elucidate the changes in aortic morphological parameters and identify the specific geometric risk factors associated with aTBAD.

METHODS

A total of 167 patients in aTBAD group and 196 subjects in control group were enrolled in the study. The aortic morphological data were retrospectively analyzed by 3mensio Vascular software. The aortic morphological parameters include diameter, length, angulation, tortuosity and the type of aortic arch. Multivariable logistic regression models were developed to identify the significant predictors associated with the angulation, tortuosity and aortic arch type. The predictive capacity of the models was evaluated through the receiver operating characteristic (ROC) curve analysis.

RESULTS

The diameters in the ascending aorta and aortic arch and the lengths in the ascending aorta and total aorta were significantly greater in aTBAD group. Besides, the angulation of the ascending aorta and aortic arch in aTBAD group increased significantly. The tortuosity of aortic arch and total aorta was significantly higher in aTBAD group. The prevalence of type III arch in aTBAD group was significantly higher than that in the controls. Multivariable models demonstrated that aortic arch angulation, tortuosity and type III arch were independent geometric predictors of aTBAD occurrence. Based on the ROC analysis, AUC of the risk prediction models was 0.977, 0.958 and 0.945, respectively.

CONCLUSIONS

Besides the enlargement of the ascending aorta and aortic arch, incremental aortic arch angulation, tortuosity and type III arch configuration are valuable geometric risk factors that could enhance aTBAD incidence.

Determination of Optimal and Safest Proximal Sealing Length During Thoracic Endovascular Aortic Repair

OBJECTIVE

To determine the optimal and safest proximal sealing length (PSL) during thoracic endovascular aortic repair (TEVAR), depending on anatomical aortic arch types and proximal landing zones (LZs).

METHODS

This was a single centre retrospective observational study of consecutive TEVAR patients (2008-2020). All aortic pathologies requiring Ishimaru landing zone (LZ) 0 - 3 were included; results were stratified by aortic arch type. The PSL was measured as the length of complete aortic wall to endograft apposition at the level of the proximal neck. The primary endpoint was proximal failure (type 1A endoleak, endograft migration, or re-intervention requiring proximal graft extension). Freedom from proximal failure was estimated with Kaplan-Meier curves. An "optimal" sealing length (PSL cutoff maximising sensitivity + specificity for proximal failure) and "safest length" (PSL cutoff determining ≥ 90% sensitivity) were identified using receiver operating characteristic curve analysis.

RESULTS

One hundred and forty patients received TEVAR; mean ± standard deviation PSL was 29 ± 9 mm. Freedom from proximal endograft failure at five years (median 31 months) was 82.4% (95% confidence interval [CI] 72 - 95); the shorter the PSL, the greater was the risk of failure (hazard ratio 0.90, 95% CI 0.84 - 0.97; p = .004). Overall optimal and safest PSL were 25 mm (sensitivity 78%, specificity 66%) and 30 mm (sensitivity 92%, specificity 30%), respectively. In type I arch, the optimal PSL was 22 mm (sensitivity 50%, specificity 87%). In type II, the optimal PSL was 25 mm (sensitivity 89%, specificity 59%) overall and 27 mm for type II/LZ 2 - 3 (sensitivity 31%, specificity 68%). For type III, the optimal PSL was 27 mm (sensitivity 80%, specificity 87%); the safest was 30 mm (sensitivity 100%, specificity 61%) In type III/LZ 2 - 3, the optimal PSL was 27 mm (sensitivity 31%, specificity 68%) and safest was 30 mm (sensitivity 100%, specificity 55%).

CONCLUSION

A 20 mm PSL may be acceptable only for type I arches. For types II/III, that represent the majority of cases, a 25 - 30 mm PSL may be required for a safe and durable TEVAR.

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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%).

CONCLUSIONS

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.

Hybrid repair versus conventional open repair for thoracic aortic arch aneurysms

BACKGROUND

Thoracic aortic arch aneurysms (TAAs) can be a life-threatening condition due to the potential risk of rupture. Treatment is recommended when the risk of rupture is greater than the risk of surgical complications. Depending on the cause, size and growth rate of the TAA, treatment may vary from close observation to emergency surgery. Aneurysms of the thoracic aorta can be managed by a number of surgical techniques. Open surgical repair (OSR) of aneurysms involves either partial or total replacement of the aorta, which is dependent on the extent of the diseased segment of the aorta. During OSR, the aneurysm is replaced with a synthetic graft. Hybrid repair (HR) involves a combination of open surgery with endovascular aortic stent graft placement. Hybrid repair requires varying degrees of invasiveness, depending on the number of supra-aortic branches that require debranching. The hybrid technique that combines supra-aortic vascular debranching with stent grafting of the aortic arch has been introduced as a therapeutic alternative. However, the short- and long-term outcomes of HR remain unclear, due to technical difficulties and complications as a result of the angulation of the aortic arch as well as handling of the arch during surgery.

OBJECTIVES

To assess the effectiveness and safety of HR versus conventional OSR for the treatment of TAAs.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 22 March 2021. We also searched references of relevant articles retrieved from the electronic search for additional citations.

SELECTION CRITERIA

We considered for inclusion in the review all published and unpublished randomised controlled trials (RCTs) and controlled clinical trials (CCTs) comparing HR to OSR for TAAs.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all titles and abstracts obtained from the literature search to identify those that met the inclusion criteria. We retrieved the full text of studies deemed as potentially relevant by at least one review author. The same review authors screened the full-text articles independently for inclusion or exclusion.

MAIN RESULTS

No RCTs or CCTs met the inclusion criteria for this review.

AUTHORS' CONCLUSIONS

Due to the lack of RCTs or CCTs, we were unable to determine the safety and effectiveness of HR compared to OSR in people with TAAs, and we are unable to provide high-certainty evidence on the optimal surgical intervention for this cohort of patients. High-quality RCTs or CCTs are necessary, addressing the objective of this review.

Drag Forces after Thoracic Endovascular Aortic Repair. General Review of the Literature

BACKGROUND

Despite the great evolution of endograft devices for thoracic endovascular aortic repair (TEVAR), threatening related complication such as graft migration and endoleaks still occur during follow up. The Drag Forces (DF), that is the displacement forces that play a role in graft migration and endoleaks caused by the blood flow against the thoracic graft, can be studied by means of Computational Fluid Dynamics (CFD).

METHOD

A general review of papers found in current literature was performed. CFD studies available on the topic of thoracic aortic diseases and DF were analyzed. All anatomic, hemodynamics or graft related factors which could have an impact on DF were reported.

RESULTS

Different factors deeply influence DF magnitude in the different site of the Ishimaru's zones classification: angulation, tortuosity and length of the landing zone, graft diameter, length and deployment position, blood pressure, pulse waveform, blood viscosity and patient heart rate have been related to the magnitude of DF. Moreover, also the three-dimensional orientation of DF is emerging as a fundamental issue from CFD studies. DF can be divided in sideways and upward components. The former, even of higher magnitude in zone 0, maintain always an orthogonal orientation and does not change in any type of aortic arch; the latter result strictly related to the anatomic complexity of the aortic arch with values up to four times higher in zone 3.

CONCLUSION

Different DF magnitude and orientation could explain how TEVAR have higher rate of migration and endoleaks when we face with more complex aortic anatomies. All these aspects should be foreseen during the planning of TEVAR procedure. In this field, collaboration between physicians and engineers is crucial, as both parts have a primary role in understanding and describing hidden aspects involved in TEVAR procedures.

Evaluation of Aortic Zone 2 Proximal Landing Accuracy During Thoracic Endovascular Aortic Repair Following Carotid-Subclavian Revascularization

BACKGROUND

Adequate seal for thoracic endovascular aortic repair (TEVAR) commonly requires landing in zone 2, but can prove to be challenging due to the tortuous and angulated anatomy of the region.

OBJECTIVES

Our objective was to determine the proximal landing accuracy of zone 2-targeted TEVARs following carotid-subclavian revascularization (CSR) and its impact on clinical outcomes.

METHODS

Retrospective review of patients that underwent CSR for zone 2 endograft delivery at a tertiary institute between January 2008 and March 2018 was conducted. Technical outcomes were assessed by examining the incidence of intraoperative corrective maneuvers, 1a endoleaks and reinterventions. Distance to target and incidence of LSA stump filling were examined as radiographic markers of landing accuracy.

RESULTS

Zone 2-targeted TEVAR with CSR was performed in 53 patients for treatment of dissections (49%), aneurysms (30%) or trauma (21%). Nine (17%) cases required intraoperative corrective procedures: 5 (9%) proximal cuffs due to type 1a endoleak and 4 (8%) left common carotid artery (LCCA) stenting due to inadvertent coverage. Cases performed using higher resolution hybrid fluoroscopy machine compared to mobile C-arm were associated with increased proximal cuff use (OR 8.8; 95% CI 1.2-62.4). Average distance between the proximal edge of the covered graft to LCCA was 8 ± 1 mm and larger distances were not associated with higher rates of 1a endoleak. Twenty-eight (53%) cases of antegrade LSA stump filling were noted on follow-up imaging, but were not associated with higher rates of reinterventions (OR 0.8, 95% CI [0.2-4.6]). Three (6%) patients had a stroke within 30 days and 4 (8%) patients expired within 1 month. Intraoperative corrective maneuvers, post-operative 1a endoleak and reinterventions were not associated with higher rates of stroke or mortality.

CONCLUSION

Using current endografts and imaging modalities, zone 2-targeted TEVARs have suboptimal technical accuracy.

Tortuosity of the Descending Thoracic Aorta in Patients with Aneurysm and Type B Dissection

OBJECTIVE

Tortuosity in the descending thoracic aorta (DTA) comes with aging and increases the risk of endoleaks after TEVAR. With this report, we would like to define and classify tortuosity in the DTA of patients with thoracic aortic disease.

METHODS

Retrospective case-control study of two hundred seven patients, comparing sixty-nine controls without aortic disease (CG), to sixty-nine patients with descending thoracic aortic aneurysm (AG) and sixty-nine patients with type B aortic dissection (DG). 3Mensio Vascular software was used to analyze CTA scans and collect the following measurements; tortuosity index, curvature ratio and the maximum tortuosity of the DTA. The DTA was divided into four equal zones. The maximum tortuosity was divided into three groups: low (<30°), moderate (30°-60°) and high tortuosity (>60°).

RESULTS

Compared to the CG, tortuosity was more pronounced in the DG, and even more in the AG, evidenced by the tortuosity index (1.11 vs. 1.20 vs. 1.31; p < 0.001), curvature ratio (1.00 vs. 1.01 vs. 1.03; p < 0.001), maximum tortuosity in degrees (28.17 vs. 33.29 vs. 43.83; p < 0.001) and group of tortuosity (p < 0.001). The maximum tortuosity was further distal for the DG and AG, evidenced by the zone of maximum tortuosity (4A vs. 4B vs. 4B; p < 0.001).

CONCLUSION

This study shows that tortuosity in the DTA is more prominent in diseased aortas, especially in aneurysmal disease. This phenomenon needs to be taken into account during planning of TEVAR to prevent stent graft-related complications and to obtain positive long-term outcome.

A multicenter "real-world" study of the valiant NAVION stent graft

BACKGROUND

The aim of the present study was to evaluate early results of thoracic endovascular aortic repair (TEVAR) using the Valiant Navion™ stent graft in a "real-world" scenario.

METHODS

All patients who underwent TEVAR with the Valiant Navion™ endograft between November 2018 and November 2019 were included in this retrospective multicenter study (six European centers). The primary endpoints were technical success, incidence of major adverse events (MAEs), access failure, deployment failure, deployment accuracy, and rate of intraoperative endoleaks (ELs).

RESULTS

One hundred-sixteen patients with varying thoracic aortic diseases were included. Eighteen patients (15.5%) were treated for an off-label condition. The technical success rate was 100%, without any access or deployment failures. The proximal and distal deployment accuracy rates were 99.1% and 97.4%, respectively. There were no intraoperative MAEs, including death. Two (1.7%) type Ib ELs were detected at the first postoperative CTA, all of which were in off-label procedures and related to the short length of the sealing neck. No type III ELs were detected. The median hospitalization time was 8 days (IQR 4-12), including a median intensive care unit stay of 1 day (IQR 1-2). The in-hospital mortality rate was 4.3%. At a median follow-up time of 98 days (IQR 39-187), there were no aortic-related mortalities or new onset of endoleaks.

CONCLUSION

Our initial experience with the Valiant Navion™ endograft in a wide variety of aortic diseases showed safe early outcomes, especially for on-label procedures.

Impact of Thoracic Endografting on the Hemodynamics of the Native Aorta: Pre- and Postoperative Assessments of Wall Shear Stress and Vorticity Using Computational Fluid Dynamics

PURPOSE

To quantify the hemodynamic consequences of thoracic endovascular aortic repair (TEVAR) by comparing the preoperative and postoperative wall shear stress (WSS) and vorticity profiles on computational fluid dynamics (CFD) simulations.

MATERIALS AND METHODS

The pre- and postoperative computed tomography (CT) scans from 20 consecutive patients (median age 69 years, range 20-87) treated for different thoracic aortic pathologies (11 aneurysms, 5 false aneurysms, 3 penetrating ulcers, and 1 traumatic aortic rupture) were segmented to construct patient-specific CFD models using a meshless code. The simulations were run over the cardiac cycle, and the WSS and vorticity values measured at the proximal and distal landing zones were compared.

RESULTS

The CFD runs provided 4-dimensional simulations of blood flow in all patients. WSS and vorticity profiles at the proximal landing zone (located in zones 0-3 in 15 patients) varied in 18 and 20 of the cases, respectively; WSS was increased in 11 cases and the vorticity in 9. Pre- and postoperative WSS median values were 4.19 and 4.90 Pa, respectively. Vorticity median values were 40.38 and 39.17 Hz, respectively.

CONCLUSION

TEVAR induces functional alterations in the native thoracic aorta, though the prognostic significance of these changes is still unknown. CFD appears to be a valuable tool to explore aortic hemodynamics, and its application in a larger series would help define a predictive role for these hemodynamic assessments.

High Wall Shear Stress Is Related to Atherosclerotic Plaque Rupture in the Aortic Arch of Patients with Cardiovascular Disease: A Study with Computational Fluid Dynamics Model and Non-Obstructive General Angioscopy

Aims: Wall shear stress (WSS) has been considered a major determinant of aortic atherosclerosis. Recently, non-obstructive general angioscopy (NOGA) was developed to visualize various atherosclerotic pathologies, including in vivo ruptured plaque (RP) in the aorta. However, the relationship between aortic RP and WSS distribution within the aortic wall is unclear. This study aimed to investigate the relationship between aortic NOGA-derived RP and the stereographic distribution of WSS by computational fluid dynamics (CFD) modeling using three-dimensional computed tomography (3D-CT) angiography.

Methods: We investigated 45 consecutive patients who underwent 3D-CT before coronary angiography and NOGA during coronary angiography. WSS in the aortic arch was measured by CFD analysis based on the finite element method using uniform inlet and outlet flow conditions. Aortic RP was detected by NOGA.

Results: Patients with a distinct RP showed a significantly higher maximum WSS value in the aortic arch than those without aortic RP (56.2±30.6 Pa vs 36.2±19.8 Pa, p =0.017), no significant difference was noted in the mean WSS between those with and without aortic RP. In a multivariate logistic regression analysis, the presence of a maximum WSS value more than a specific value was a significant predictor of aortic RP (odds ratio 7.21, 95% confidence interval 1.78-37.1, p =0.005).

Conclusions: Aortic RP detected by NOGA was strongly associated with a higher maximum WSS in the aortic arch derived by CFD using 3D-CT. The maximum WSS value may have an important role in the underlying mechanism of not only aortic atherosclerosis, but also aortic RP.

Poor concordance between definitions of type III arch and implications for risk prediction and assessment for carotid artery stenting

OBJECTIVE

The type III arch configuration has been inconsistently reported as a stroke risk factor during carotid artery stenting. However, at least three different methods for the definition of type III arch can be identified in the literature, related to the level of the origin of the innominate artery (IA). According to Casserly's definition, a type III arch presents with an origin of the IA below the horizontal plane of the inner curvature. According to Madhwal's definition, a type III arch has a distance greater than twice the diameter of the left common carotid artery between the highest point of the arch and the origin of the IA. According to MacDonald's definition, a type III arch presents with a distance of ≥2 cm between the highest point of the arch and the origin of the IA. Our aim was to assess the level of concordance between these different methods.

METHODS

Anonymized thoracic computed tomography scans of 100 healthy patients were reviewed. Two of us independently stratified the selected cases as a type I to III arch, according to the three considered definitions. The interobserver level of concordance for each type III arch classification and level of concordance among the three definitions were assessed.

RESULTS

The 100 selected patients (64% male) were 76 ± 7 years old. For each definition, the interobserver repeatability was almost perfect for all three (Madhwal, κ = 0.81; 95% confidence interval [CI], 0.71-0.99; MacDonald, κ = 0.82; 95% CI, 0.72-0.92; Casserly, κ = 0.84; 95% CI, 0.74-0.93). The level of concordance among the different definitions was very low (Madhwal vs MacDonald, 85% [P = .002]; 33% for type III arch; Madhwal vs Casserly, 60% [P < .0001]; 12% for type III arch; MacDonald vs Casserly, 75% [P < .0001]; 12% for type III arch).

CONCLUSIONS

The three definitions of the type III arch have a very low level of concordance, which might account for the varying clinical relevance of this configuration. Our findings have relevant implications for risk prediction for carotid artery stenting based on the presence of a type III arch, for comparisons of the results from different studies, and for comparisons of different datasets from multicenter trials.

Computational Fluid Dynamics Modeling of Proximal Landing Zones for Thoracic Endovascular Aortic Repair in the Bovine Arch Variant

BACKGROUND

To assess the endograft displacement forces (DF), which quantify the forces exerted by the pulsatile blood flow on the vessel wall and transmitted on the terminal fixation site of the endograft after its deployment in proximal landing zones (PLZs) of the bovine aortic arch variant.

METHODS

Thirty healthy aortic computed tomographic angiographies of subjects with bovine arch configuration (10 per type of arch, I-III) were selected for the purpose of the study. A 3-dimensional model of the aortic arch lumen was reconstructed. Computational fluid dynamics modeling was then used to compute DF magnitude and orientation (i.e., x, y, and z axes) in PLZs of each case. DF values were normalized to the corresponding aortic wall area to estimate equivalent surface traction (EST).

RESULTS

DF were highest in zone 0, consistently with the greater surface area. DF in zone 3 were much greater than in zone 2 because of a 3-fold greater upward component (z axis) (P < 0.001), being therefore mainly oriented orthogonally to the aortic blood flow and to the vessel longitudinal axis in that zone. EST progressively increased from zone 0 toward more distal PLZs, with EST in zone 3 being much greater than that in zone 2 (P < 0.001). The same pattern was observed after stratification by type of arch.

CONCLUSIONS

The bovine arch is associated with a consistent fluid dynamic pattern, which identifies in zone 3 an unfavorable biomechanical environment for endograft deployment.

Type III Arch Configuration as a Risk Factor for Carotid Artery Stenting: A Systematic Review of Contemporary Guidelines on Management of Carotid Artery Stenosis

BACKGROUND

Type III arch configuration is frequently reported as a stroke risk factor for carotid angioplasty and stenting (CAS). We reviewed contemporary guidelines on management of carotid artery stenosis to assess the clinical relevance attributed to this anatomic feature in current clinical practice.

METHODS

The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. The PubMed, EMBASE, and Web of Science databases were searched to identify all guidelines on extracranial carotid disease published between January 2008 and March 2020. A total of 435 articles were screened. For multiple guidelines from the same writing group, only the most recent updated version was considered. Eighteen documents were identified for qualitative analysis.

RESULTS

Four guidelines specifically reported type III arch as a predictive factor of periprocedural complications after CAS. Two of them also provided a low level of evidence of their recommendation. None of the documents indicated the exact criteria for aortic arch classification. Three different methods to describe type III arch configuration were identified.

CONCLUSIONS

Type III arch configuration is inconsistently included among stroke risk factors for CAS in contemporary guidelines, and variably defined. Further studies on the level of concordance between the 3 existing definition criteria are warranted.

Hoarseness Caused by a Penetrating Proximal Descending Thoracic Aortic Ulcer and Pseudoaneurysm

We present a case of an 87-year-old female with new-onset hoarseness of unclear etiology. Imaging demonstrated a penetrating aortic ulcer (PAU) in the proximal descending thoracic aorta with an associated pseudoaneurysm that enlarged to a depth of 32 mm over 2 years. This patient was diagnosed with hoarseness being secondary to left recurrent laryngeal nerve (LRLN) palsy, a variant of Ortner syndrome. Patient was treated with endovascular stent-grafting successfully covering of the PAU and pseudoaneurysm with zone 3 proximal landing zone. The patient had moderate improvement in hoarseness after 1 year of follow-up. Endovascular repair is indicated for symptomatic patients with PAUs complicated by enlarging pseudoaneurysms or rupture. Endovascular treatment is effective with low procedural morbidity and mortality. In this case, the PAU and associated pseudoaneurysm at the level of the ligamentum arteriosum caused compression on the LRLN, resulting in a nerve palsy and hoarseness. This case highlights the importance of vascular imaging for patients presenting with unclear etiology of hoarseness or other signs of LRLN palsy. Therefore, aortic arch abnormalities, a variant of Ortner syndrome, even though rare, should be on the differential diagnosis of new onset hoarseness.

Geometric Pattern of Proximal Landing Zones for Thoracic Endovascular Aortic Repair in the Bovine Arch Variant

OBJECTIVE

The aim was to investigate whether the "bovine" aortic arch (i.e. arch variant with a common origin of the innominate and left carotid artery (CILCA)) is associated with a consistent geometric configuration of proximal landing zones for thoracic endovascular aortic repair (TEVAR).

METHODS

Anonymised thoracic computed tomography (CT) scans of healthy aortas were reviewed to retrieve 100 cases of CILCA. Suitable cases were stratified according to type 1 and 2 CILCA, and also based on type of arch (I, II, and III). Further processing allowed calculation of angulation and tortuosity of the proximal landing zones. Centre lumen line lengths of each proximal landing zone were measured in a view perpendicular to the centre line. All geometric features were compared with those measured in healthy patients with a standard arch configuration (n = 60). Two senior authors independently evaluated the CT scans, and intra- and interobserver repeatability were assessed.

RESULTS

The 100 selected patients (63% male) were 71.4 ± 7.7 years old. Type 1 CILCA (62/100) was more prevalent than type 2 CILCA (38/100), and the two groups were comparable in age (p = .11). Zone 3 presented a severe angulation (i.e. > 60°), which was greater than in Zone 2 (p < .001), and a consistently greater tortuosity than Zone 2 (p = .003). This pattern did not differ between type 1 and type 2 CILCA. A greater tortuosity was also observed in Zone 0, which was related to increased elongation of the ascending aorta (i.e. Zone 0), than the standard configuration. The CILCA had an overall greater elongation, and Zone 2 also was specifically longer. When stratifying by type of arch, reversely from Type III to Type I, the CILCA presented a gradual flattening of its transverse tract, which entailed a consistent progressive elongation (p = .03) and kinking of the ascending aorta, with a significant increase of Zone 0 angulation to even a severe degree (p = .001). Also, from Type III to Type I, Zone 2 presented a progressively shorter length (p = .004), which was associated with increased tortuosity (p < .05). Mean intra- and interobserver differences for angulation measurements were 1.4° ± 6.8° (p = .17) and 2.0° ± 10.1° (p = .19), respectively.

CONCLUSION

CILCA presents a consistent and peculiar geometric pattern compared with standard arch configuration, which provides relevant information for TEVAR planning, and may have prognostic implications.

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.

3D printing of aortic models as a teaching tool for improving understanding of aortic disease

BACKGROUND

A geometrical understanding of the individual patient's disease morphology is crucial in aortic surgery. The aim of our study was to validate a questionnaire addressing understanding of aortic disease and use this questionnaire to investigate the value of 3D printing as a teaching tool for surgical trainees.

METHODS

Anonymized CT-angiography images of six different patients were selected as didactic cases of aortic disease and made into 3D models of transparent rigid resin with the Vat-photopolymerization technique. The 3D aortic models, which could be disassembled and reassembled, were displayed to 37 surgical trainees, immediately after a seminar on aortic disease. A questionnaire was developed to compare the trainees' understanding before (T0) and after (T1) demonstration of the 3D printed models.

RESULTS

A panel of 15 experts participated in evaluating face and content validity of the questionnaire. The questionnaire validity was established and therefore the information investigated by the questionnaire could be synthetized using the mean of the items to indicate the understanding. The participants (mean age 28 years, range 26-34, male 59%) showed a significant improvement in understanding from T0 (median=7.25; IQR=1.50) to T1 (median=8.00; IQR=1.50; P=0.002).

CONCLUSIONS

Preliminary data suggest that the use of 3D-printed aortic models as a teaching tool was feasible and improved the understanding of aortic disease among surgical trainees.

Tortuosity of the descending thoracic aorta: Normal values by age

Background

Aging changes the aorta in length, tortuosity and diameter. This is relevant in thoracic endovascular aortic repair (TEVAR) and in the long term follow up.

Methods and results

Two groups of hundred patients < 65 years and hundred patients ≥ 65 years, with no vascular diseases were made. Thin cut CT scans were analyzed with 3Mensio Vascular software and the following measurements were collected; tortuosity index, curvature ratio, maximum tortuosity in degrees and the level of vertebrae of the maximum tortuosity. The descending thoracic aorta (DTA) was analyzed and was divided into four zones of equal length. Subjects were divided into three groups based on their maximum tortuosity value: low (< 30°), moderate (30° – 60°) and high (> 60°). A linear regression model was built to test the effect of age and gender on tortuosity. Tortuosity was more pronounced in the ≥ 65 compared to the < 65 group (tortuosity index: 1.05 vs. 1.14, respectively; p < 0.001), curvature ratio (1.00 vs. 1.01; p < 0.001), maximum tortuosity (22.24 vs. 27.26; p < 0.001), and group of angulation (low vs. low; p < 0.001). Additionally, the location of maximum tortuosity was further distal for the ≥ 65 group (level of vertebrae; 5.00 vs. 5.00; p < 0.001), and zone of maximum tortuosity (4A vs. 4A; p < 0.001). There was no significant difference between male and female subjects.

Conclusion

Normal DTA tortuosity increases with age. This is important to understand natural aging and for TEVAR planning and follow-up.