Morphology of Aortic Arch Pathology: Implications for Endovascular Repair

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.

Effect of aortic curvature on bioprosthetic aortic valve performance

Transvalvular pressure gradient (ΔP) after aortic valve replacement is an important surrogate of aortic bioprostheses performance. Invasive ΔP is often measured after transcatheter aortic valve replacement to exclude patient-prosthetic mismatch. However, invasive aortic pressures are usually recorded in the pressure recovery (PR) zone downstream of the valve, potentially resulting in ΔP underestimation compared to noninvasive measurements. PR was extensively studied in straight ascending aortas. However, the impact of various aortic arch configurations on ΔP has not been explored. PR was assessed in a pulse duplicating simulator at various cardiac conditions of cardiac output, heart rates and pressures. Three different aortic geometries with identical root dimensions but with different aortic arches were used: (1) curvature 1, (2) curvature 2, and (3) straight aortic models. Instantaneous pressure and peak ΔP measurements were recorded incrementally along the models for each cardiac condition. The models with aortic arches produced two distinct PR zones (after the valve and after the aortic arch), whereas the model without an aortic arch produced only one PR zone (after the valve). The trend of the pressure and ΔP curves for each model was independent of the cardiac condition used, but the individually measured pressure magnitudes did change with different conditions. In this study, we illustrated the differences in PR between distinct aortic curvatures and straight aorta. PR affects pressure and ΔP measurements. These effects are clear when recording aortic pressures by catheterization and echocardiography.

RELAY™ Branched device: The story of an aortic arch device

BACKGROUND

The management of aortic arch pathologies represents a great challenge and is associated with high rates of mortality and morbidity. The invasive and radical open surgical repair (OSR) is the standard of care for this group of patients. A superior endovascular approach via thoracic endovascular aortic repair (TEVAR) has been introduced to treat arch pathologies with specifically designed endografts. This approach was shown to benefit patients who are deemed "high risk" for undergoing OSR as it is a greatly less invasiveness option and thus, yields lower rates of morbidity and mortality.

AIMS

This commentary aims to discuss the recent study by Tan and colleagues, which reports original data on the neurological outcomes after endovascular repair of the aortic arch using the RELAY™ Branched device.

METHODS

We carried out a literature search on multiple electronic databases, including PubMed, Ovid, Google Scholar, Scopus, and EMBASE, to collate research evidence on the neurological outcomes of endovascular aortic arch repair with TEVAR.

RESULTS

Tan and colleagues showed through their original clinical data that the RELAY™ Branched device has a high rate of technical success and favorable neurological outcomes. There were no reported neurological deficits in patients who received the triple-branched RELAY™ Branched device.

CONCLUSION

The RELAY™ branched endograft is well-established for candidates for aortic arch endovascular repair with favorable neurological outcomes. Multiple considerations can help control the incidence of stroke following endovascular repair. These include optimization of the supra-aortic vessels' revascularization, weighting the embolic risk in patients with atheromatous disease, and careful preoperative assessment to select the best candidates for arch endovascular repair.

Favorable neurological outcomes in thoracic endovascular aortic repair with RELAY™ branched-An international perspective

BACKGROUND

While open surgical repair continues to be the mainstay option for aortic arch reconstruction, the associated mortality, morbidity, and high turn-down rates have led to a need for the development of minimally invasive options for aortic arch repair. Though RELAY™ Branched (Terumo Aortic, Inchinnan, UK) represents a promising option for complex endovascular aortic arch repair, neurological complications remain a pertinent risk. Herein we seek to present multicenter data from Europe documenting the neurological outcomes associated with RELAY™ Branched.

METHODS

Prospective data collected between January 2019 and January 2022 associated with patients treated with RELAY™ single-, double-, and triple-branched endoprostheses from centers across Europe was retrospectively analyzed with descriptive and distributive analysis. Follow-up data from 30 days and 6, 12, and 24 months postoperatively were included. Patient follow-up was evaluated for the onset of disabling stroke (DS) and non-disabling stroke (NDS).

RESULTS

Technical success was achieved in 147 (99.3%) cases. Over 24 months period, in total, six (4.1%) patients suffered DS, and eight (5.4%) patients suffered NDS after undergoing aortic arch repair with RELAY™. All patients that developed postoperative DS had been treated with the double-branched RELAY™ endoprosthesis.

DISCUSSION

The data presented herein demonstrates that RELAY™ Branched is associated with favorable neurological outcomes and excellent technical success rates. Key design features of the endoprosthesis and good perioperative management can contribute greatly to mitigating neurological complications following endovascular aortic arch repair.

Does endovascular duration impact clinical outcomes in aortic arch repair? The RELAY™ branched international stance

Background

The high mortality and morbidity rates in surgical aortic arch repair are a barrier to therapy for a considerable proportion of patients with aortic arch aneurysm or dissection. There is hence a demand for the development and adoption of a minimally invasive alternative to aortic arch repair, such as thoracic endovascular aortic repair (TEVAR). Procedural duration is a key factor in the pathogenesis of complications in surgical aortic arch repair. Herein, we evaluate whether endovascular duration impacts neurological outcomes, target vessel patency, and reintervention rates in aortic arch TEVAR with RELAY™ Branched (Terumo Aortic, Inchinnan, UK), which is specifically developed for on-label use within the aortic arch.

Methods

Prospective data was collected between January 2019 and January 2022 on the clinical outcomes of TEVAR for aortic arch dissection and aneurysm with RELAY™ single-, double-, and triple branched endoprostheses from centers across Europe. They were then retrospectively analyzed with descriptive and distributive analysis. Follow-up data on the incidence of disabling stroke (DS), target vessel patency, and reintervention from 30 days and 6-, 12-, and 24 months postoperative was included in the analysis.

Results

147 (99.3%) of all 148 cases were successful. Over the 24 month follow-up period, in total 6 (4.1%) patients suffered DS, 24 (16.3%) required reintervention, and target vessel patency was exhibited in 118 (80.2%) patients. The modal endovascular duration was 100-150 min (in 64.6%, n = 95 cases). Analysis revealed that endovascular duration was associated with a lower likelihood of reintervention at 30 days, 6-, and 12 months (P = 0.011, P = 0.019, P = 0.037), a greater likelihood of target vessel patency at 6- and 24 months (P = 0.032, P = 0.035). No relationship between endovascular duration and DS was revealed.

Discussion

The data demonstrates that RELAY™ Branched is associated with promising clinical outcomes for on-label aortic arch TEVAR. The underlying mechanism linking endovascular duration and reintervention rates, or target vessel patency is likely multifactorial and complex. Given that TEVAR is carried out under general anesthetic only, it is unlikely that prolonged procedural duration has any major effect over neurological outcomes for arch TEVAR.

The characteristics of distal tears affect false lumen thrombosis rate after thoracic endovascular aortic repair for acute type B dissection

OBJECTIVES

A low false lumen thrombosis rate (FLTR) is common in patients with type B aortic dissection after they have undergone thoracic endovascular aortic repair, which indicates a poor long-term prognosis. This study aimed to establish a quantitative linear regression model to predict false lumen (FL) thrombosis accurately using morphological parameters.

METHODS

In this retrospective study, we included 59 patients diagnosed with acute type B aortic dissection between 2014 and 2017. Morphological parameters were measured. Univariable and multivariable linear regression analyses were performed, and a linear regression model relating FLTR with the number of re-entry tears was proposed. Ten patients were further chosen to validate the linear relationship, and idealized aortic dissection models were adopted for haemodynamic analysis.

RESULTS

Only the total area and number of re-entry tears were negatively correlated with FL thrombosis (P < 0.001). Moreover, based on the univariable regression, the number of re-entry tears played a more crucial role in FLTR (R2 = 0.509 vs R2 = 0.298), and the linear relationship model was created as follows: thrombosis rate (%) = -11.25 × distal tear number + 105.24. This model was perfectly matched in 10 patients (concordance correlation coefficient = 0.880, P = 0.947). Moreover, when the total area of re-entry tears was constant, the net blood flow increased rapidly with an increase in the tear count.

CONCLUSIONS

The number of re-entry tears could be a crucial related factor of FL thrombosis; the larger the number of re-entry tears is, the lower the possibility of thrombosis is.

Exploration of Simplified Intraluminal TEVAR Technique for the Treatment of Aortic Arch Disease

Objective:

The positional relationship between the three branches of the aortic arch was determined in normal people. This study provides data to support the customization of aortic arch stents and simplifies intraluminal treatment.

Methods:

From January 2019 to August 2019, 120 patients who met the inclusion criteria were examined by CT angiography. The ratio of the distance from the midpoint of the three-branch opening onto the anterior wall to the cross-sectional diameter of the aortic arch was calculated. The positional relationship among the three-branch openings was obtained and the data were analyzed statistically.

Results:

The three-branch openings were not in a straight line. The positional relationship among the three-branch openings was divided into four types, which were not statistically different between sex and age (P>0.05).

Conclusion:

By measuring the opening position of the three aortic branches, the positional relationship among the three branches was defined to provide a theoretical basis for the design of intraluminal stents and simplified intracavity thoracic endovascular aortic repair (TEVAR) technology.

Anatomic feasibility of off-the-shelf thoracic single side-branched endograft in patients with blunt traumatic thoracic aortic injury

OBJECTIVE

The advent of thoracic single side-branched endograft (TSSBE) has provided a treatment option to obviate the need for open cervical debranching of the left subclavian artery (LSA), thereby enabling total endovascular incorporation of the LSA during thoracic endovascular aortic repair (TEVAR). In a previous study of patients with type B aortic dissection who had required zone 2 TEVAR, the anatomic feasibility of this device was demonstrated to range from 28% to 35%, suggesting limited applicability of the currently available designs. The objectives of the present study were twofold: (1) to evaluate the anatomic feasibility of TSSBE in blunt traumatic thoracic aortic injury (BTAI) patients who would require LSA revascularization; and (2) to describe the anatomic characteristics of the supra-aortic arch branches that could be used to improve future device design.

METHODS

A retrospective review was performed of BTAI patients who had undergone TEVAR at a single institution from November 2013 to October 2018. Preoperative computed tomography angiograms were analyzed using three-dimensional reconstruction to quantify the aortic diameter, distance and arc length between branch vessels, and the LSA diameter and length. We calculated the proportion of patients who had met all aortic and LSA anatomic requirements for TSSBE proposed by investigational protocols. We also assessed the effect of anatomic requirement modifications on device suitability. Finally, we assessed the local anatomic relationship between the supra-aortic branches.

RESULTS

A total of 41 patients (63% men; median age, 39 years; range, 23-88 years; 68% normal aortic arch pattern, 32% bovine aortic arch pattern) with BTAI who had required TEVAR involving the LSA and were, thus, considered potential candidates for TSSBE were included. Of the 41 patients, 13 (32%; 7 with a bovine aortic arch and 6 with a normal aortic arch) had met all proposed aortic and LSA anatomic requirements for TSSBE. An appropriate aortic diameter, LSA diameter, and LSA length to its first branch were observed in 100%, 95%, and 66% of the patients, respectively. An insufficient distance between the arch branch vessels, observed in 41%, was the most common exclusionary criterion. The median clock-face position of the LSA was 12:00 (interquartile range, 30 minutes) in the normal arch group and 11:45 (interquartile range, 15 minutes) in the bovine arch group.

CONCLUSIONS

Despite the numerous potential advantages of TSSBE, only 32% of patients with BTAI requiring LSA revascularization had met all the aortic and LSA anatomic requirements, justifying the need for additional designs. Better characterization and mapping of the aortic arch branches will improve future device design and application.

Prediction of 3D Cardiovascular hemodynamics before and after coronary artery bypass surgery via deep learning

The clinical treatment planning of coronary heart disease requires hemodynamic parameters to provide proper guidance. Computational fluid dynamics (CFD) is gradually used in the simulation of cardiovascular hemodynamics. However, for the patient-specific model, the complex operation and high computational cost of CFD hinder its clinical application. To deal with these problems, we develop cardiovascular hemodynamic point datasets and a dual sampling channel deep learning network, which can analyze and reproduce the relationship between the cardiovascular geometry and internal hemodynamics. The statistical analysis shows that the hemodynamic prediction results of deep learning are in agreement with the conventional CFD method, but the calculation time is reduced 600-fold. In terms of over 2 million nodes, prediction accuracy of around 90%, computational efficiency to predict cardiovascular hemodynamics within 1 second, and universality for evaluating complex arterial system, our deep learning method can meet the needs of most situations.

Anatomical Analysis and Feasibility Study of Next-Generation Fenestrated or Branched Stent-Grafts for the Treatment of Arch Aneurysms

Purpose: To analyze the anatomical characteristics of arch aneurysms and evaluate the anatomical feasibility of 4 next-generation stent-grafts with either branched or fenestrated configurations. Materials and Methods: A retrospective analysis was conducted of 213 patients (mean age 75.0±7.1 years; 179 men) with arch aneurysms treated using total arch replacement or zone 0 or 1 thoracic endovascular aortic repair (TEVAR) from 2007 to 2017 at 2 Japanese hospitals. Anatomical analyses were performed using the centerline of flow technique on a 3-dimensional workstation. The anatomical feasibility of the Zenith A-branch, TAG Thoracic Branch Endoprosthesis (TBE), Terumo Aortic Relay Plus Double Branched (DB), and fenestrated Najuta stent-grafts were evaluated based on the instructions for use (IFU). Results: The mean lengths from the sinotubular junction (STJ) to the innominate artery (IA) and from the IA to the left common carotid artery were 114.9±15.9 and 12.8±5.6 mm, respectively. The mean aortic diameters at the STJ and IA were 31.3±3.4 and 34.1±5.3 mm, respectively. In terms of feasibility, 5.2% of patients were within the Zenith A-branch IFU, 40.8% for the TAG TBE, 24.9% for the Relay Plus DB, and 13.6% for the Najuta. Significant (>50% circumference) thrombus/calcification at the sealing zone affected nearly half of the patients, but there is currently no standardized definition or evaluation method for "significant" thrombus/calcification. Conclusion: Only 5% to 41% of arch aneurysm patients are anatomically suitable for TEVAR using any one of the next-generation branched or fenestrated stent-grafts. Furthermore, a definitive method of evaluating the thrombus/calcification burden needs to be established in future IFU.

Aortic Arch Anatomy Pattern in Patients Treated Using Double Homemade Fenestrated Stent-Grafts for Total Endovascular Aortic Arch Repair

Purpose: To analyze the structural variation of the aortic arch and the supra-aortic arteries and establish an average spatial configuration that would be a pattern for a “universal double fenestration” design for physician-modified endovascular grafts (PMEGs) used in total thoracic endovascular aortic repair (TEVAR). Materials and Methods: Aortic arch morphology was retrospectively analyzed by reviewing the preoperative thoracic computed tomography angiography scans in 33 consecutive patients (mean age 68 years; 27 men) treated between January 2017 and March 2019 using double-fenestrated PMEGs for zone 0 TEVAR. Image analysis was completed according to a standardized technique on a vascular workstation with center lumen line reconstruction for all measurements. Variations in branching pattern of the aortic arch were classified into 8 types. Results: The arch trunk configuration was type I in 26 patients (79%), type II in 5 (15%), type III in 1, and type IV in 1. Mean aortic diameters at the level of mid ascending aorta, innominate artery (IA), left common carotid artery (LCCA), and left subclavian artery (LSA) were 35.7±3.7, 34.2±4.5, 33.3±6.7, and 33.7±4.7 mm, respectively. Mean diameters of the trunk were 12.2±1.7, 7.5±1.4, and 8.0±0.8 mm, respectively. Mean longitudinal center to center lengths were 15.9±2.5 mm between the LSA and LCCA and 12.1±3.0 mm between the LCCA and IA. Mean clock positions using the LSA as reference were 12:50 for the IA and 12:05 for the LCCA. In 32 patients (97%) all the supra-aortic branch vessels fit perfectly inside two delimited areas defined by a proximal common square area of 30×30 mm for the IA and LCCA and a second distal 8-mm-diameter circle for the LSA. Conclusion: Variations of the aortic arch anatomy are numerous and common. A general morphological pattern is described that delimits the aortic area where these variations occur. This information can be utilized for the design of an off-the-shelf double-fenestrated stent-graft for zone 0 TEVAR.

Endovascular aortic repairs combined with looping-chimney technique for repairing aortic arch lesions and reconstructing left common carotid artery

Background

The aim of this retrospective study was to evaluate the feasibility and efficacy of thoracic endovascular aortic repairs (TEVAR) combined with looping chimney technique (LCT) for repairing aortic arch lesions and reconstructing left common carotid artery.

Methods

Total of 14 patients (mean age 52.86±14.46 years; range, 27–79; 10 men, 4 women) were included in the study from December 2016 to December 2018. Aortic arch pathologies of all patients with insufficient proximal landing zone (PLZ) were repaired by TEVAR under local anesthesia, before TEVAR, the left common carotid artery (LCCA) was protected by the guiding sheath from the retrograde brachial access, after aortic stent graft deployed, chimney graft was implanted to restore LCCA by LCT if necessary. All patients underwent computed tomography angiograph (CTA) 2 weeks, 3 months, 6 months and 1 year after surgery.

Results

Pathology results of 14 patients included: type B aortic dissection (n=8), penetrating aortic ulcers (n=1), retrograde type A aortic dissection (n=1), thoracic aortic aneurysm (TAA) (n=2), and thoracic aortic pseudoaneurysm (n=2). In all patients, aortic arch lesions were repaired by TEVAR; while LCCA were successfully reconstructed by the LCT. In one case, the innominate artery (IA) was simultaneously reconstructed through the same percutaneous right brachial artery (RBA) access. Coiling eliminated type Ia endoleak in 3 patients, and type II endoleak vanished by plugging left subclavian artery (LSA) in 2 patients. In four patients, the chimney stent (CG) of LCCA was partially compressed and then another bare stent was implanted to restore patency rate. The mean follow-up duration was 9.77±6.64 months (range, 0–24) and no combinations were observed in 13 patients; except in one patient who died of cerebral hemorrhage due to abnormal coagulation function.

Conclusions

TEVAR combined with LCT has shown to be suitable surgical approach for aortic arch lesions. Either covered intentionally or inadvertently, the LCCA could be safely and effectively reconstructed via percutaneous RBA access. Short-term follow-up demonstrated satisfactory morbidity and mortality in high-risk patients; however, longer follow-up is required to assess the effectiveness and durability of this innovative endovascular procedure.

Endovascular management of chronic post-dissection aneurysms of the aortic arch

This article reviews endovascular management of chronic post-dissection aneurysms of the aortic arch. Therapeutic strategies intended for this complex aortic condition are evolving rapidly to allow the treatment of various hostile aortic anatomy and frail patients. Principles, technical considerations, devices and outcomes of each technique are reviewed and summarized. Hybrid repair offer similar early mortality and stroke rates compared to open conventional surgery. Arch chimney and other parallel graft techniques present poor long term outcome, and should be limited to emergency situations where no other option is available. Fenestrated stent-grafting is subjected to many technical challenges in aortic arch due to difficulties in stent-graft orientation and fenestration positioning. In situ fenestration is an off-label technique that should only be used as an emergency bailout maneuver, considering that temporary coverage of supra aortic trunk vessel and its long-term durability raise concern. Finally, in experienced hands and appropriate anatomic conditions, arch branched graft technology has shown itself to be a safe and effective alternative to open conventional surgery. No randomized controlled trials have yet compared total endovascular aortic arch repair with hybrid techniques and open arch repair. The management of chronic post-dissection aneurysms of the aortic arch is challenging, decision-making and interventions should continue to be performed in high-volume centers with a dedicated aortic team with an expertise in both open and endovascular repairs.

Early Postnatal Echocardiography in Neonates with a Prenatal Suspicion of Coarctation of the Aorta

Coarctation of the aorta (COA) is suspected prenatally when there is ventricular asymmetry, arterial disproportion, and hypoplasia of the aortic arch/isthmus. The presence of fetal shunts creates difficulty in prenatal confirmation of the diagnosis so serial echocardiography after birth is necessary to confirm or refute the diagnosis. The first neonatal echocardiogram in prenatally suspected cases of COA was assessed for prediction of neonatal COA repair (NCOAR). This included morphological assessment, measurement of the aortic arch and calculation of the distal arch index (DAI = distance between left common carotid and left subclavian artery/diameter of the distal arch). NCOAR was undertaken in 23/60 (38%) cases. Transverse arch, aortic isthmus z-score, and DAI had an area under the receiver operator curve of 0.88 (95% CI 0.77-0.98), 0.86 (95% CI 0.75-0.96), and 0.84 (95% CI 0.74-0.95), respectively for the prediction of NCOAR. Using transverse arch z-score threshold < - 3 gave sensitivity 100%, NPV: 100%, specificity 76%; aortic isthmus z-score  < - 3: NPV 92%, specificity 62% and DAI > 1.4: NPV 88%, specificity 78%. The size of the distal aortic arch in infants with a common origin of the innominate artery and left common carotid artery who did not require COA repair was similar to the NCOAR cases (p = 0.22). The early postnatal assessment of the size and morphology of the aortic arch can assist in risk stratification for development of neonatal COA. The branching pattern of the head/neck vessels impacts on the size of the distal aortic arch adding to the complexity of predicting COA based on vessel size.

The Role of Dual-Source Computed Tomography Angiography in Evaluating the Aortic Arch Vessels in Acute Type A Aortic Dissection: A Retrospective Study of 42 Patients

Background

This study aimed to investigate the role of dual-source computed tomography angiography (DSCTA) to evaluate the anatomy of the aortic arch vessels in patients with acute Type A aortic dissection (AD).

Material/Methods

A retrospective clinical study included 42 patients with acute Type A AD who underwent DSCTA and were treated in our hospital between January 2018 and December 2018. The findings were compared with a control group of 45 healthy individuals with hypertension and without aortic arch lesions.

Results

The diagnostic accuracy of DSCTA in patients with acute Type A AD was almost 100%. The innominate artery was most frequently affected. The mean DSCTA imaging measurements for the root of the innominate artery, the left common carotid artery, and the left subclavian artery, in the coronal plane of the aortic arch, were 17.7±3.7 mm, 17.7±3.7 mm, and 12.9±3.1 mm, respectively. The angles formed by the origin of the three aortic arch branches vessels and the aortic arch were 70.5±10.2°, 58.5±15.5°, and 90.2±22.7°, respectively. In the transverse plane of the aortic arch, the mean angles were 110.5±22.3°, 100.3±15.2°, and 95.4±10.6°, respectively. These DSCTA imaging findings were significantly different in the patient group compared with the control group.

Conclusions

DCTA demonstrated that patients with Type A AD showed anatomic differences in the aortic arch vessels. These findings may help surgeons to develop treatment strategies and select the most appropriate vascular grafts and stents.

Predictor of false lumen thrombosis after thoracic endovascular aortic repair for type B dissection

OBJECTIVE

Thoracic endovascular aortic repair of type B aortic dissection initiates thrombosis in the false lumen, which eventually results in aortic remodeling. We aimed to determine whether the false lumen thrombosis rate (FLTR) after thoracic endovascular aortic repair can be accurately predicted by an index that expresses the degree of aortic arch angulation.

METHODS

The geometry of 48 patients with acute type B aortic dissection (mean age, 48 years) after thoracic endovascular aortic repair was reconstructed from postoperative computed tomography images. We introduced a novel angle-the degree of question mark (φ)-to indicate the aortic morphology. Moreover, how aortic angulation influenced the FLTR was investigated based on hemodynamic parameters. Finally, a predicted mathematical model relating FLTR to aortic angulation was proposed, and 10 patients were chosen to validate the model.

RESULTS

The degree of question mark shape was shown to negatively correlate with FLTR (n = 38; P < .001; R = -0.661), and the linear relationship model was created as follows: FLTR (%) = -1.955 × φ + 168.24 (R² = 0.437; P < .001). In addition, the net flow rate to the false lumen significantly increased with the increase of the degree of the question mark shape of the aorta. Furthermore, the difference and concordance of the proposed prediction model were perfectly validated in the remaining 10 patients using paired-sample t test and the concordance correlation coefficient.

CONCLUSIONS

The size of the question mark shape may be a good predictor for FLTR of acute type B aortic dissection following thoracic endovascular aortic repair. The higher the degrees of the question mark, the less likely it was to form a complete thrombus.

Predictive Numerical Simulations of Double Branch Stent-Graft Deployment in an Aortic Arch Aneurysm

Total endovascular repair of the aortic arch represents a promising option for patients ineligible to open surgery. Custom-made design of stent-grafts (SG), such as the Terumo Aortic^® RelayBranch device (DB), requires complex preoperative measures. Accurate SG deployment is required to avoid intraoperative or postoperative complications, which is extremely challenging in the aortic arch. In that context, our aim is to develop a computational tool able to predict SG deployment in such highly complex situations. A patient-specific case is performed with complete deployment of the DB and its bridging stents in an aneurysmal aortic arch. Deviations of our simulation predictions from actual stent positions are estimated based on post-operative scan and a sensitivity analysis is performed to assess the effects of material parameters. Results show a very good agreement between simulations and post-operative scan, with especially a torsion effect, which is successfully reproduced by our simulation. Relative diameter, transverse and longitudinal deviations are of 3.2 ± 4.0%, 2.6 ± 2.9 mm and 5.2 ± 3.5 mm respectively. Our numerical simulations show their ability to successfully predict the DB deployment in complex anatomy. The results emphasize the potential of computational simulations to assist practitioners in planning and performing complex and secure interventions.

A compliant aortic model for in vitro simulations: Design and manufacturing process

We design and manufacture a silicone model of the human aorta, able to mimic both the geometrical and the mechanical properties of physiological individuals, with a specific focus on reproducing the compliance. In fact, while the models available in the literature exhibit an unrealistic compliant behavior, though they are detailed from the geometrical viewpoint, here the goal is to provide an accurate compliant tool for in vitro testing the devices that interface with the vascular system. A parametric design of the aortic model is obtained based on the available literature data, and the model is manufactured with a specific silicone mixture using rapid prototyping and molding techniques. The manufactured prototype has been tested by means of computed tomography scans for evaluating the matching of the mechanical properties with the desired ones. Results show a high degree of adherence between the imposed and the measured compliance values for each main aortic section. Thus, our work proves the feasibility of the approach, and the possibility to manufacture compliant models that reproduce the mechanical behavior of the aorta for in vitro studies.

A simple patient-tailored aortic arch tangential angle measuring method to achieve better clinical results for thoracic endovascular repair of type B aortic dissection

Background

To report a simple individual tailored aortic arch tangential angle (θ-AATA) measuring method and its clinical application efficacy in the endovascular treatment of type B aortic dissection (AD).

Methods

From January 2013 to December 2014, acute type B AD patients were prospectively enrolled and treated with endovascular therapy in our center. Among these patients, a specific method was applied to measure θ-AATA based on the axial images of the CT scan. The length of proximal landing zone (PLZ) of each patient was measured at the routinely applied left-anterior oblique (LAO) 45-degree and θ-AATA. Respective treatment strategies based on the length of the PLZ were planned accordingly, and the stent-graft was deployed under the fluoroscopy at θ-AATA. The occurrence of immediate type I endoleak was recorded during the completion angiogram, while the alignment of the proximal marks was determined under fluoroscopy at θ-AATA and at LAO-45-degree as well.

Results

Totally 76 patients with type B AD were prospectively enrolled. The average value of θ-AATA was 58.3±5.2 degrees, which was significantly larger than the routine 45 degrees (P<0.01). The mean landing zone length measured under θ-AATA (18.4±3.9 mm) was longer than that (15.9±3.1 mm) obtained at the routine LAO-45 degrees (P<0.05). Stent-grafts' deployment strategies were substantially changed accordingly. Alignment of the proximal marks was achieved in 72 patients (93.4%) under θ-AATA and only in two patients (2.7%) at LAO-45 degrees (P<0.01). All stent-grafts' implantation was successfully completed. No major type I endoleak was found in the immediate post-deployment angiography.

Conclusions

It is easy to apply this patient-tailored θ-AATA measuring method in clinical practice. This more precise measurement is benefit for more reasonable treatment strategy planning, more precise deployment, and therefore a better outcome.

CT patterns of acute type A aortic arch dissection: longer, higher, more anterior

OBJECTIVES

This study analysed CT patterns of the acute dissected aortic arch using original biometric features along with comparison with normal aortas.

METHODS

The diagnostic CT scans of 57 patients (42 males, age (mean ± SD: 64.5 ± 13.8 years) admitted with acute Stanford type A dissection involving the aortic arch were analysed by semi-automatic detection protocol of the true lumen of the dissection. We measured the distances from the apex to the ascending and descending aorta, the curvilinear length of the entire arch and of its segments (especially between the brachiocephalic artery trunk and the left subclavian artery), as well as the surface area, angle, height and shift of the arch. These measurements were compared with results previously obtained in a healthy cohort in an analysis adjusted for age, sex and weight. The surface area and rotation of the false lumen were also analysed.

RESULTS

Compared to normal aortic arches (N), dissected aortic arches (D) were longer (D: 155 ± 26  mm, N: 135 ± 25  mm, p = 0.002), higher (D: 51 ± 10  mm, N: 45 ± 9  mm, p = 0.04), and with a more anterior apex (shift: D: 1.19 ± 0.56, N: 1.40 ± 0.62, p = 0.007). False lumen occupied between 47-65% of the aorta, turned preferentially clockwise and its rotation decreased progressively along the arch.

CONCLUSIONS

The morphology of the dissected aortic arch differs from that of the normal arch. Thus, our compilation of aortic arch measurements may help improve existing endovascular devices and/or design of new endoprostheses. Advances in knowledge: In this article, we provide a comprehensive set of measurements of the dissected aortic arch, and show that dissected aortic arches are longer, higher, and with a more anterior apex than normal arches.

The apex of the aortic arch backshifts with aging

BACKGROUND

Only a few studies, involving small numbers of patients, have globally assessed the curvature of the thoracic aorta but without any details concerning the location of the supra-aortic trunks.

OBJECTIVES

Using CT to describe normal aortic-arch morphology and its changes with age and sex.

METHODS

344 CT scans were studied. We measured the distances from the apex to the ascending and descending aorta, the curvilinear length of the entire arch, that of the segment, including bifurcations of supra-aortic vessels, and the angle, height, and shift of the arch.

RESULTS

In men, the arch was significantly longer (146.2 vs 122.8 mm; p < 0.001), higher (49.3 vs 40.1 mm, p < 0.001), and wider transversely (83.6 vs 73.3 mm; p < 0.001) than in women. The average men's arch also had a more acute angle at the apex (79.7° vs 83.7° p < 0.001). Neither morphology nor age influenced the winding angle around the mediastinum. Aging was accompanied by deflection and extension of the aortic arch, which grew more anteroposteriorly (6.1 mm/10 years in men) than vertically (2.5 mm/10 years in men), while the apex moved towards the rear of the arch. The ascending aorta was the only curvilinear length unaffected by age, whereas the supra-aortic trunks parted from each other.

CONCLUSION

We believe that all these original observations could lead to a better assessment of normal aging of the aorta and guide technical choices during surgical or hybrid procedures.

Aortic Arch Morphology and Aortic Length in Patients with Dissection, Traumatic, and Aneurysmal Disease

OBJECTIVES

To assess aortic arch morphology and aortic length in patients with dissection, traumatic injury, and aneurysm undergoing TEVAR, and to identify characteristics specific to different pathologies.

METHOD

This was a retrospective analysis of the aortic arch morphology and aortic length of dissection, traumatic injury, and aneurysmal patients. Computed tomography imaging was evaluated of 210 patients (49 dissection, 99 traumatic injury, 62 aneurysm) enrolled in three trials that received the conformable GORE TAG thoracic endoprosthesis. The mean age of trauma patients was 43 ± 19.6 years, 57 ± 11.7 years for dissection and 72 ± 9.6 years for aneurysm patients. A standardized protocol was used to measure aortic arch diameter, length, and take-off angle and clockface orientation of branch vessels. Differences in arch anatomy and length were assessed using ANOVA and independent t tests.

RESULTS

Of the 210 arches evaluated, 22% had arch vessel common trunk configurations. The aortic diameter and the distance from the left main coronary (LMC) to the left common carotid (LCC) were greater in dissection patients than in trauma or aneurysm patients (p < .001). Aortic diameter in aneurysm patients was greater compared with trauma patients (p < .05). The distances from the branch vessels to the celiac artery (CA) were greater in dissection and aneurysm patients than in trauma patients (p < .001). The take-off angle of the innominate (I), LCCA, and left subclavian (LS) were greater, between 19% and 36%, in trauma patients than in dissection and aneurysm patients (p < .001). Clockface orientation of the arch vessels varies between pathologies.

CONCLUSIONS

Arch anatomy has significant morphologic differences when comparing aortic pathologies. Describing these differences in a large sample of patients is beneficial for device designs and patient selection.

Surgically relevant aortic arch mapping using computed tomography

BACKGROUND

Recent advances in surgical repair of aortic arch pathologies have increasingly used endovascular stent-graft technology. The purpose of this study was to map the aortic arch diameters, branch orientations, and center line distances using a commercially available three-dimensional computed tomography-based software package and to propose a prototype design.

METHODS

TeraRecon 3D imaging software was used for morphological assessment of computed tomography scans from 45 patients (mean age: 68 years; 26 males, 19 females). In each patient, 13 measurements were made in relation to the center line, including diameters at several preset points, distances, and branch vessel orientations.

RESULTS

The mode of the proximal diameters (2 cm and 4 cm distal to coronary artery) was 32 mm and 34 mm. The mode of the distance between the innominate and left common carotid arteries was 5 mm and 6 mm, and the mode of the distance between the left common carotid artery and left subclavian artery was 8 mm. Most commonly, the left common carotid artery was anterior to the other arch branches by 3 to 5 mm.

CONCLUSIONS

These anatomic measurements provide useful information for the advancement of minimally invasive and safer surgical repair of the aortic arch. Based on the most commonly observed measurements, a standardized off-the-shelf stent-graft is proposed that would be appropriate for the majority of patients.