Toward endovascular treatment of type A aortic dissection with smaller landing zones and more patient eligibility.

OBJECTIVE: Type A or ascending aortic dissection is an acute life-threatening condition with high morbidity and mortality. Open surgery remains the standard of care. The development of minimally invasive endografts for type A aortic dissection (TAAD) will require a detailed understanding of the dissection and aortic root anatomy to determine patient eligibility and optimal device specifications. METHODS: Computed tomography images of TAAD cases at our institution from 2012 to 2019 were identified, and three-dimensional reconstructions were performed using OsiriX, version 10.0 (Pixmeo SARL, Bernex, Switzerland). We analyzed key anatomic structures, including centerline length measurements, ascending aorta and aortic root dimensions, and the location and extent of dissection in relationship to the coronary ostia. RESULTS: A total of 53 patients were identified (mean ± standard deviation age, 60.4 ± 17.1 years; 36 men and 17 women), 46 of whom had undergone surgery for TAAD. Four patients had died within 30 days of surgery. In 47 patients (88.7%), the entry tear was distal to the highest coronary ostium. These cases were retrospectively considered for endovascular intervention using a nonbranched, single endograft stent. The proximal landing zone (LZ) was defined as the distance from the highest coronary ostium to the entry tear. Of the 53 patients, 35 (66.0%) had a proximal LZ length of ≥2.0 cm, 38 (71.7%) had a proximal LZ length of ≥1.5 cm, and 42 (79.2%) had a proximal LZ length of ≥1.0 cm. The median proximal and distal LZ diameters of the sinotubular junction (STJ) and distal ascending aorta regions were 3.29 cm (interquartile range [IQR], 2.73-4.10 cm) and 3.49 cm (IQR, 3.09-3.87 cm, respectively), with a median length from the STJ to the innominate takeoff of 8.08 cm (IQR, 6.96-9.40 cm). The median ascending aorta radius of curvature was 6.48 cm (IQR, 5.27-8.00 cm). Of the 53 patients, 25 (47.2%) could be treated with a straight tube graft with a ≤20% diameter mismatch between the proximal and distal LZs. CONCLUSIONS: Almost 80% of the patients with TAAD had had a proximal LZ of ≥1.0 cm. Of these patients, 47.2% had anatomy amenable for endovascular therapy with a nontapered straight tube graft using commercially available devices. To increase patient eligibility for TAAD endovascular intervention, enhanced precision deployment with an adequate seal in shorter LZs will be required. Our results can serve as a guide for endovascular device specifications designed to treat this devastating condition.

The Role of Multiple Re-Entry Tears in Type B Aortic Dissection Progression: A Longitudinal Study Using a Controlled Swine Model.

PURPOSE: False lumen (FL) expansion often occurs in type B aortic dissection (TBAD) and has been associated with the presence of re-entry tears. This longitudinal study aims to elucidate the role of re-entry tears in the progression of TBAD using a controlled swine model, by assessing aortic hemodynamics through combined imaging and computational modeling. MATERIALS AND METHODS: A TBAD swine model with a primary entry tear at 7 cm distal to the left subclavian artery was created in a previous study. In the current study, reintervention was carried out in this swine model to induce 2 additional re-entry tears of approximately 5 mm in diameter. Computed tomography (CT) and 4-dimensional (4D) flow magnetic resonance imaging (MRI) scans were taken at multiple follow-ups before and after reintervention. Changes in aortic volume were measured on CT scans, and hemodynamic parameters were evaluated based on dynamic data acquired with 4D-flow MRI and computational fluid dynamics simulations incorporating all available in vivo data. RESULTS: Morphological analysis showed FL growth of 20% following the initial TBAD-growth stabilized after the creation of additional tears and eventually FL volume reduced by 6%. Increasing the number of re-entry tears from 1 to 2 caused flow redistribution, with the percentage of true lumen (TL) flow increasing from 56% to 78%; altered local velocities; reduced wall shear stress surrounding the tears; and led to a reduction in FL pressure and pressure difference between the 2 lumina. CONCLUSION: This study combined extensive in vivo imaging data with sophisticated computational methods to show that additional re-entry tears can alter dissection hemodynamics through redistribution of flow between the TL and FL. This helps to reduce FL pressure, which could potentially stabilize aortic growth and lead to reversal of FL expansion. This work provides a starting point for further study into the use of fenestration in controlling undesirable FL expansion. CLINICAL IMPACT: Aortic growth and false lumen (FL) patency are associated with the presence of re-entry tears in type B aortic dissection (TBAD) patients. Guidelines on how to treat re-entry tears are lacking, especially with regards to the control and prevention of FL expansion. Through a combined imagining and computational hemodynamics study of a controlled swine model, we found that increasing the number of re-entry tears reduced FL pressure and cross lumen pressure difference, potentially stabilising aortic growth and leading to FL reduction. Our findings provide a starting point for further study into the use of fenestration in controlling undesirable FL expansion.

Early Experience With a Novel Dissection-Specific Stent-Graft to Prevent Distal Stent-Graft-Induced New Entry Tears After Thoracic Endovascular Repair of Chronic Type B Aortic Dissections.

BACKGROUND: The aim was to report short and mid-term outcomes of a novel, investigational, dissection-specific stent-graft (DSSG), specifically designed to address the features of chronic type B aortic dissection (CTBAD) and reduce the risk of distal stent-graft-induced new entry tears (dSINE). MATERIALS AND METHODS: A retrospective single center cohort study of all patients undergoing TEVAR with the DSSG for CTBAD from January 1, 2017 to January 31, 2020. The DSSG, which is a modified stent-graft based on the Cook Zenith Alpha Thoracic platform, has no proximal barbs, and a customized longer body length with substantial taper. The second and third distal Z-stents are sited internally to avoid any contact of the metal skeleton with the dissection membrane and have reduced radial force, while the most distal stent was removed creating a distal 30 mm unsupported Dacron graft. RESULTS: Sixteen patients (13 males, 3 females) with a median age of 66 years (range 31-79 years) underwent elective TEVAR of CTBAD using the DSSG. Six patients (38%) had an underlying connective tissue disorder. The median tapering was 10 mm (range 4 mm-21 mm) and median length 270 mm (range 210-380 mm). Technical success was achieved in all but one case (96%). One patient died within 30 days, due to retrograde type A dissection with cardiac tamponade. The 30-day rate of stroke, spinal cord ischemia, and re-interventions was 0%. After median imaging follow-up time of 17 months (range 1-31 months), one patient developed a dSINE 4 months after the index procedure. After median survival follow-up of 23 months (range 2-35 months), one late death occurred due to traumatic brain injury, while no aortic-related death occurred during follow-up. Complete false lumen (FL) thrombosis was achieved in 9 patients while the remaining 6 showed partial FL thrombosis. No instances of diameter increase at the level oftreated aortic segment were noted with serial measurements showing either stable (n = 7) or decreased (n = 8) maximal transverse diameter. CONCLUSIONS: Use of a novel DSSG with low radial force for TEVAR in the setting of CTBAD is safe and feasible. This early real-world experience shows promising mid-term effectiveness with low rates of dSINE or unplanned re-interventions and satisfactory aortic remodeling during follow-up. Longer follow-up is needed, however, before any firm conclusions can be drawn.

Current evidence in predictors of aortic growth and events in acute type B aortic dissection.

OBJECTIVES: Acute type B aortic dissection can have a stable course or evolve into aneurysm and subsequent adverse events. The aim of this systematic review was to analyze the morphologic predictors of an adverse course to establish their validity based on consistency of results. METHODS: Fifty-one studies were included in this review, reporting on aortic size, false lumen (FL) size, primary entry tear (ET) size and location, status of FL thrombosis, number of ETs, branch vessels involvement, and FL longitudinal extent. RESULTS: Some predictors showed good consistency, whereas others did not. Aortic size was the most investigated predictor. A larger diameter at presentation predicted worse outcomes, with few exceptions. Both FL size and size relative to true lumen size also predicted an adverse course, although a standardized measurement method was not used. Regarding primary ET size and location, evidence was sparse and somewhat conflicting. Although FL complete thrombosis was consistently associated with a more benign course, the role of partial thrombosis remained unclear and the concept of FL saccular formation might account for the inconsistency, but further evidence is needed. A higher number of re-entry tears was considered to be protective against false channel expansion, but results need to be confirmed. The predictive role of branch vessels involvement and FL longitudinal extent remain controversial. CONCLUSIONS: Among several predictors of aortic growth and events in acute type B aortic dissection, controversial and even conflicting results have been described. Consistent evidence has been demonstrated only for two predictors: aortic size at presentation is associated with adverse events and total FL thrombosis has a protective role.

Physician-Modified Thoracic Stent-Graft With Low Distal Radial Force to Prevent Distal Stent-Graft-Induced New Entry Tears in Patients With Genetic Aortic Syndromes and Aortic Dissection.

PURPOSE: To describe a novel modification technique to lower the distal radial force of a thoracic stent-graft so as to avert stent-graft-induced new entry tears (SINE) in the fragile aorta of patients with genetic aortic disease and aortic dissection. TECHNIQUE: A commercially available thoracic stent-graft is partially deployed on a back table. The most distal Z-stent is removed, the distal fabric is marked by vascular clips, and the modified stent-graft is reloaded and deployed in the true lumen of an aortic dissection. The technique is demonstrated in 3 patients with aortic dissection related to genetic aortic diseases. CONCLUSION: Creating a low distal radial force stent-graft is easy and can be done in a short time. Endovascular implantation appears feasible and safe.

Standardized Protocol to Analyze Computed Tomography Imaging of Type B Aortic Dissections.

PURPOSE: To propose a standard measuring protocol for type B aortic dissections so as to improve comparability between studies reporting aortic dimensions. METHODS: Fifteen computed tomography (CT) scans of type B aortic dissections were measured with a standard protocol by 2 independent observers using postprocessing software. The following parameters were assessed: true, false, and total lumen diameter; true and false lumen volume; and entry tear size, location, and number. Diameters were measured in a perpendicular plane at 2, 10, and 20 cm from the left subclavian artery and 5 cm from the most distal renal artery. True lumen volume was assessed from the left subclavian artery to the aortic bifurcation, while the false lumen volume was from the start to end up to the aortic bifurcation. Entry tear location was assessed in relation to the left subclavian artery. Intra- and interobserver repeatability and agreement were evaluated using the Bland-Altman method, an a priori set of acceptable differences, and Lin's concordance correlation coefficient (LCCC). RESULTS: Intra- and interobserver mean differences for aortic diameter and true and false lumen volumes were generally within the limits of agreement and the a priori differences; the LCCC showed excellent agreement. Entry tear location, size, and number were difficult to measure in a repeatable manner, with inconsistent correlation coefficients, especially between the 2 observers. CONCLUSION: This protocol showed acceptable repeatability for aortic diameter and aortic volume measurements. Assessment of entry tears proved challenging and associated with less favorable results. Additionally, investigators are urged to be more transparent regarding the measurement methodology used in studies describing aortic dimensions.

An analysis of initial and follow-up CT findings in intramural hematoma, aortic double-lumen dissection, and mixed type lesions.

BACKGROUND: Although the clinical presentation of intramural hematoma (IMH) and aortic double-lumen dissection (AD) is similar, the imaging results and subsequent clinical course of the two lesions differ. PURPOSE: To compare the clinical and radiological findings of IMH, AD, and mixed type lesions. MATERIAL AND METHODS: Forty-two patients with IMH, 38 with AD, and 10 with mixed type lesions were imaged with post-contrast-enhanced CT. The most proximal ulcer-like lesions and entry tears and the distal ends of the IMH and AD were evaluated. The interval change of the intramural hematoma, ulcer-like lesion, and false lumen was observed. The pathological findings of the aorta were evaluated in 15 patients. RESULTS: The most proximal ulcer-like lesion and entry tear were located in the arch to the descending aorta in 27 (64.2%) of the 42 patients with IMH and in 24 (63.1%) of the 38 patients with AD. The distal extension was located at the iliac arteries in six (14.3%) patients with IMH and in 31 (81.6%) patients with AD (P < 0.001). The intramural hematomas regressed in 29 (93.5%) of 31 patients, and the ulcer-like lesion progressed in 14 (70%) of 20 patients with IMH. The clinical features of the mixed type lesions resembled those of AD, rather than IMH. The intramural hematoma or dissection was observed within the outer media in all lesion types on histopathology. CONCLUSION: There is a distinct difference between IMH and AD in distal extension; however, the locations of the lesions are pathologically the same in the media of the aorta.

Computed tomography-based study exploring the feasibility of endovascular treatment of type A aortic dissection in the Chinese population.

PURPOSE: To characterize type A aortic dissection (TAAD) in the Chinese population using high-resolution computed tomography (CT) and explore potential candidacy for endovascular repair of TAAD. METHODS: The imaging studies and medical records of all 302 patients presenting with TAAD at two Chinese hospitals from 2010 to 2013 were reviewed. Of these, 221 patients were excluded because of missing/inadequate preoperative CT scans. The remaining 91 patients (64 men; mean age 51.1±7.5 years) had CT data adequate to assess anatomical suitability for endovascular treatment. Entry tears were identified using multiplanar reconstructions, while morphological measurements were based on a centerline of flow (CLF) technique. Suitability for endovascular treatment was based on a proximal landing zone ≥20 mm long, a true lumen aortic diameter ≤38 mm, and a total aortic diameter ≤46 mm; no coronary bypass grafts originating from the ascending aorta; no malfunctioning aortic valve; and good cerebral and cardiac perfusion. RESULTS: In the 91 patients, the precise location of the primary proximal entry tear could be identified in only 34 (37.4%) patients; in these patients, the identifiable intimal tears were located 36.4±41.0 mm distal to the closest coronary artery. The CLF was successfully generated in the CT scans of all patients; the mean lumen and total aortic lumen diameters at the entry tear level were 37.6±6.3 and 44.3±13.3 mm, respectively. Based on the CT measurements, stent-graft repair would have been anatomically feasible in 35 (38.5%) patients. No proximal landing zone (n=23), large aortic diameter (n=15), abnormal aortic valve (n=10), previous coronary bypass graft surgery (n=5), and poor cerebral and cardiac perfusion (n=3) were obstacles that affected the suitability for this treatment. CONCLUSION: Based on high-resolution CT scans, our pilot study suggested that 38% of Chinese patients with TAAD could potentially be treated by stent-grafting based on the anatomical characteristics of the proximal dissection.

Staging reinterventions for remodeling of residual aortic dissection: a single-center retrospective study.

Objective: Inadequate remodeling of residual aortic dissection (RAD) following repair of Stanford A or B aortic dissections has been identified as a significant predictor of patient mortality. This study evaluates the short- to mid-term outcomes of staged reinterventions for RAD at a single center with prospective follow-up. Methods: Data were retrospectively collected from patients with RAD who underwent staged reinterventions or received none-surgery treatment in the Cardiovascular Surgery Department of our hospital between July 2019 and December 2021. The cohort included 54 patients with residual distal aortic dissection post-primary surgery, comprising 28 who underwent open surgery and 26 who received thoracic endovascular aortic repair (TEVAR). Patients were divided into two groups: those who underwent staged stent interventions for distal dissection [staged reintervention (SR) group] and those who did not undergo surgery (non-surgery group). For the SR group, second or third staged stent interventions were performed. The study assessed distal remodeling of aortic dissection between the groups, focusing on endpoints such as mortality (both general and aortic-specific), occurrences of visceral branch occlusion, necessity for further interventions, and significant adverse events. Morphological changes were analyzed to determine the therapeutic impact. Results: The study encompassed 54 participants, with 33 in the SR group and 21 in the non-surgical control group. Baseline demographics and clinical characteristics were statistically comparable across both groups. During an average follow-up of 31.5 ± 7.0 months, aortic-related mortality was 0% in both groups; all-cause mortality was 3% (one case) and 5% (one case) in the SR and control groups, respectively, with no statistically significant difference noted. In the SR group, a single patient experienced complications, including renal artery thrombosis, leading to diminished blood flow. An increased true lumen (TL) area and a decreased false lumen area at various aortic planes were observed in the SR group compared to the control group. Conclusion: The staged reintervention strategy for treating RAD is safe and provides promising early results.

Three-dimensional modelling and hemodynamic simulation of the closure of multiple entry tears in type B aortic dissection.

BACKGROUND: Stanford type B aortic dissection (TB-AD) is a life-threatening vascular condition with high rates of morbidity and mortality. Currently, thoracic endovascular aortic repair (TEVAR) is widely performed to treat TB-AD, and some studies have analyzed the influence of stents on hemodynamics using computational fluid dynamics (CFD) models. However, the accuracy of TB-AD simulation models are not satisfactory, they are often constructed as a regular ideal model. Furthermore, it is unclear which tear should be closed for the best treatment when there are multi entry tears. PURPOSE: The aims of this paper were to provide an assessment method for the selection of the surgical closure location for type B aortic dissection. Five 3D models of multiple entry tears in type B aortic dissection were produced using real patient computed tomography (CT) images to perform hemodynamic analyses of flow velocity streamlines, wall pressure, and wall shear stress. METHODS: A Boolean operation was adopted to establish 3D models with multiple entry tears in type B aortic dissection based on patient-specific CT images. The Mimics and Ansys plug-in The Integrated Computer Engineering and Manufacturing code for Computational Fluid Dynamics (ICEM CFD) software were applied to mesh the 3D models. The flow velocity streamlines, wall pressures, and wall shear stresses were then analyzed in the finite element analysis software Fluent. Five 3D models were produced to compare the hemodynamic characteristics of different entry tear numbers, as well as the changes of different closure positions before and after closure. RESULTS: The false lumen of the model with two entry tears had a higher wall pressure than that of model with multiple entry tears, which may tend to squeeze the true lumen and expand the false lumen. The load distribution of the vessel in the model with multiple entry tears had a more balanced flow velocity, and its wall pressure and shear stress were lower than that of model with two entry tears. For aortic dissection with two entry tears, the closure of the proximal entry tear was recommended, which helped to isolate and thrombose the false lumen, thereby improving the blood supply function of the true lumen. Because the postoperative vascular flow velocity and mechanical load performance of the vascular wall were still higher than those of normal blood vessels, the postoperative blood vessels remained pathological, and TEVAR did not restore the blood vessels to their original healthy state. CONCLUSIONS: Type B aortic dissection with two entry tears tend to squeeze the true lumen and expand the false lumen, resulting in a new entry tear and deterioration into multiple entry type B aortic dissection. The model of the vessel with multiple entry tears had a more balanced distribution in flow velocity and a smaller wall pressure and shear stress than that of the vessel with two entry tears. The closure of the proximal entry tear was considered an ideal solution for type B aortic dissection with two entry tears.

Design, evolution, and experience with the candy plug device for endovascular false lumen occlusion of chronic aortic dissections.

INTRODUCTION: The management of the false lumen (FL) when dealing with aortic dissection is a crucial aspect since inducing its thrombosis is necessary in order to achieve aortic remodeling. One of the pitfalls of endovascular treatment of aortic dissection (AD) is retrograde distal FL perfusion and pressurization, which prevents FL thrombosis and thus aortic remodeling, while being associated with aneurysmal degeneration of the FL and poor long-term outcomes. AREAS COVERED: Currently, there is no CE/FDA approved device for FL closure, however different techniques and devices have been proposed to overcome this challenge, the most known of which is the Candy Plug (CP). This review aims to describe the CP device, its implantation technique, and the available data in the literature (PubMed, Cochrane, and EMBASE databases; last queried, December 31, 2023). EXPERT OPINIONS: While the treatment of AD remains technically challenging, the use of the CP technique to close any distal FL reperfusion proved to be feasible and safe with excellent rates of both technical and clinical success. Furthermore, recent studies have shown a quick learning curve with this technique.

Diameter changes of the thoracic aorta caused by acute type B aortic dissection.

BACKGROUND: The impact of type B acute aortic dissection (TBAAD) on historical pre-TBAAD diameters of the thoracic aorta is rarely reported. The aim of this study was to assess the extent of changes in aortic diameters induced by dissection, measured with a computed tomography (CT) scan obtained before and after TBAAD. METHODS: Between January 2004 and December 2014, CT angiography of 50 non-Marfan patients with nonbicuspid aortic valves diagnosed with TBAAD were compared to historical CTs on file. RESULTS: The ascending aorta and proximal arch showed negligible change. The proximal, mid, and distal aorta diameters changed compared with predissected values (107.7 ± 4.8%, 109.3 ± 4.9%, and 105.7 ± 5.8%, respectively). Neither sex, false lumen status, or mural calcification, nor prior thoracoabdominal aortic ectasia, correlated with the diameter change. Age ≥80 years in the proximal descending aorta did correlate with the diameter change (110.7 ± 4.0% vs 106.1 ± 4.6% p = 0.01). CONCLUSIONS: Although identifying predicting factors for an aortic diameter increase all along with the thoracic aorta was still challenging, the degree of diameter change by aortic dissection was 105.7% to 109.3% in descending thoracic aorta, most prominent in middle descending aorta.

Feasibility of Total Endovascular Repair of the Aorta in Patients with Acute Type A Aortic Dissection: Morphological Analysis of 119 Patients.

(1) Background: This study aimed to morphologically analyze acute type A aortic dissection (aTAAD) patients for potential endovascular treatment candidates. The objective was to specify requirements for aTAAD endovascular devices. (2) Methods: A single-center retrospective analysis included aTAAD patients who underwent open surgical repair between November 2005 and December 2020. Preoperative CTA scans were used for morphological analysis, assessing endovascular repair eligibility. Statistical tests were performed. (3) Results: A total of 129 patients with aTAAD were studied, with 119 included. Entry tear (ET) locations were identified, mainly in the aortic root, 20 mm above the sinotubular junction (STJ) and within the ascending aorta (20 mm above STJ to -20 mm before the brachiocephalic trunk). Endovascular treatment was deemed feasible for 36 patients, with suggested solutions for the aortic arch and descending aorta. Significant differences were observed between eligible and noneligible groups for aortic diameter, false lumen diameter, distance between STJ and entry tear, and more. Dissection extension showed no significant difference. (4) Conclusions: Morphological analysis identified potential aTAAD candidates for endovascular treatment, highlighting differences between eligible and noneligible morphologies. This study offers insights for implementing endovascular approaches in aTAAD treatment and emphasizes the need for research and standardized protocols.

Association of Ductus Diverticulum and Acute Type B Aortic Dissection.

RATIONALE AND OBJECTIVES: An anatomic association between ductus diverticulum and the primary entry tear in type B aortic dissection was observed. The aim was to reveal the association between ductus diverticulum and acute type B aortic dissection. MATERIALS AND METHODS: A matched case-control study was conducted. Case subjects were extracted from consecutive patients with aortic dissection in the emergency department during 2019; the control subjects were extracted from consecutive patients without major aortic disease during 2019. 1:1 matching was performed for age, sex, and comorbidity, the prevalence of ductus diverticulum was compared, and conditional logistic regression was performed to reveal the association of ductus diverticulum and acute type B aortic dissection. In addition, the anatomic association between the ductus diverticulum and the primary entry tear was assessed in extracted cases, and baseline parameters were compared between dissection patients with or without ductus diverticulum. RESULTS: 128 cases and 402 control subjects were extracted. 86 pairs were formed after matching, and the proportion of ductus diverticulum (19.8% vs 1.2%, p < 0.001) was higher in the case group. Conditional logistic regression revealed ductus diverticulum(OR = 22.04, 95%CI: 2.81-172.76, p = 0.003) as an independent predictor for acute type B aortic dissection. Besides, the ductus diverticulum has an anatomic association with the primary entry tear (OR = 4.22, 95%CI: 1.46-12.25, p = 0.008), and dissection patients with ductus diverticulum were younger (47.9 vs 54.4, p = 0.015) than dissection patients without ductus diverticulum. CONCLUSION: Ductus diverticulum is common in acute type B aortic dissection and is independently associated with acute type B aortic dissection.

A Novel Endovascular Double-Disc Implant for Sealing Intimal Tears in Aortic Dissection.

Postdissection thoracoabdominal aortic aneurysm incidence after thoracic endovascular aortic repair for type B aortic dissection is high, with residual distal tears being a major reason for persistent blood flow in the false lumen. The EndoPatch is an endovascular double-disc implant for sealing re-entry tears in aortic dissection, isolating blood flow in the false lumen and promoting thrombosis formation. Compared with conventional endovascular treatment techniques, this endovascular double-disc implant's small size and minimal working space requirements may reduce the risk of spinal ischemia and offer flexible vascular access. Although several barriers still impede this endovascular device's broad application, its innovative design, flexible vascular access, and streamlined surgical process make it a promising alternative for managing intimal tears in aortic dissection, either alone or as a supplementary method combined with conventional endovascular techniques. (Guo's Entry Tear Repair: The First in Man Study of Endopatch System; NCT04745039).

A computational study of the effects of size, location, and number of tears on haemodynamics in surgically repaired type A aortic dissection.

Objective: This study aimed to comprehensively examine the roles of size, location, and number of tears in the progression of surgically repaired type A aortic dissection (TAAD) by assessing haemodynamic changes through patient-specific computational fluid dynamic (CFD) simulations. Methods: Two patient-specific TAAD geometries with replaced ascending aorta were reconstructed based upon computed 15 tomography (CT) scans, after which 10 hypothetical models (5 per patient) with different tear configurations were artificially created. CFD simulations were performed on all the models under physiologically realistic boundary conditions. Results: Our simulation results showed that increasing either the size or number of the re-entry tears reduced the luminal pressure difference (LPD) and maximum time-averaged wall shear stress (TAWSS), as well as areas exposed to abnormally high or low TAWSS values. Models with a large re-entry tear outperformed the others by reducing the maximum LPD by 1.88 mmHg and 7.39 mmHg, for patients 1 and 2, respectively. Moreover, proximally located re-entry tears in the descending aorta were more effective at reducing LPD than distal re-entry tears. Discussion: These computational results indicate that the presence of a relatively large re-entry tear in the proximal descending aorta might help stabilize post-surgery aortic growth. This finding has important implications for the management and risk stratification of surgically repaired TAAD patients. Nevertheless, further validation in a large patient cohort is needed.

Management of acute aortic syndrome with evolving individualized precision medicine solutions: Lessons learned over two decades and literature review.

Background: Thoracoabdominal acute aortic syndrome is associated with high morbidity and mortality. We aim to scrutinize our evolving strategies for acute aortic syndrome (AAS) management using minimally invasive and adaptive surgical techniques over two decades. Methods: This is a longitudinal observational study at our tertiary vascular centre from 2002 to 2021. Out of 22,349 aortic referrals, we performed 1,555 aortic interventions over twenty years. Amongst 96 presented with symptomatic aortic thoracic pathology, 71 patients had AAS. Our primary endpoint is combined aneurysm-related and cardiovascular-related mortality. Results: There were 43 males and 28 females (5 Traumatic Aortic Transection (TAT), 8 Acute Aortic Intramural Hematoma (IMH), 27 Symptomatic Aortic Dissection (SAD) and 31 Thoracic Aortic Aneurysm (TAA) post-SAD) with a mean age of 69. All the patients with AAS received optimal medical therapy (OMT), but TAT patients underwent emergency thoracic endovascular aortic repair (TEVAR). Fifty-eight patients had an aortic dissection, of which 31 developed TAA. These 31 patients with SAD and TAA received OMT initially and interval surgical intervention with TEVAR or sTaged hybrId sinGle lumEn Reconstruction (TIGER). To increase our landing area, we performed a left subclavian chimney graft with TEVAR in twelve patients. The average follow-up duration was 78.2 months, and eleven patients (15.5%) had combined aneurysm and cardiovascular-related mortality. Twenty-six percentage of the patients developed endoleaks (EL), of which 15% required re-intervention for type II and III. Four patients who had paraplegia (5.7%) and developed renal failure died. None of our patients had a stroke or bowel ischaemia. Twenty patients had OMT, eight of these were patients with acute aortic hematoma, and all eight died within 30 days of presentation. Conclusion: Acute aortic hematoma is a sinister finding, which must be closely monitored, and consideration is given to early intervention. Paraplegia and renal failure result in an increased mortality rate. TIGER technique with interval TEVAR has salvaged complex situations in young patients. Left subclavian chimney increases our landing area and abolishes SINE. Our experience shows that minimally invasive techniques could be a viable option for AAS.

The role of aorta distal to stent in the occurrence of distal stent graft-induced new entry tear: A computational fluid dynamics and morphological study.

Distal stent graft-induced new entry tear (dSINE) is an important complication of thoracic endovascular aortic repair (TEVAR) for the treatment of type B aortic dissection (TBAD). This study aims to explore whether the aorta distal to the stent plays an important role in the occurrence of dSINE. Sixty-nine patient-specific geometrical models of twenty-three enrolled patients were reconstructed from preoperative, postoperative, and predSINE computed tomography scans. Computational fluid dynamics (CFD) simulations were performed to calculate the von Mises stress in the CFD group. Meanwhile, morphological measurements were performed in all patients, including measurements of the inverted pyramid index at different follow-up time points and the postoperative true lumen volume change rate. In the CFD study, the time-averaged von Mises stress of the true lumen distal to the stent in dSINE patients was significantly higher than that in the CFD controls (20.42 kPa vs. 15.47 kPa). In the morphological study, a special aortic plane (plane A) with an extremely small area distal to the stent was observed in dSINE patients, which resulted in an inverted pyramid structure in the true lumen distal to the stent. This structure in dSINE patients became increasingly obvious during the follow-up period and finally reached the maximum value before dSINE occurred (mean, 3.91 vs. 1.23). At the same time, enlargement of the true lumen distal to the stent occurs before dSINE, manifesting as a continuous increase in the true lumen volume (mean, 0.70 vs. 013). A new theory of what causes dSINE to occur has been proposed: the inverted pyramid structure of the true lumen distal to the stent caused an increase in the von Mises stress in this region and aortic enlargement, which ultimately led to the occurrence of dSINE.

The efficacy and safety of Gore conformable thoracic stent graft and Valiant Captivia thoracic stent graft for acute type B aortic dissection.

BACKGROUND: To evaluate the safety and efficacy of the conformable thoracic aortic endograft (Conformable TAG Thoracic Endoprosthesis [CTAG]; W. L. Gore & Associates, Flagstaff, Ariz) and Valiant Captivia thoracic stent graft (Medtronic Inc., Santa Rosa, CA) for acute type B aortic dissection (TBAD). METHODS: The early and mid-term outcomes were analyzed for 413 patients undergoing TEVAR using conformable TAG thoracic endoprosthesis and Valiant Captivia thoracic stent graft for acute TBAD. 100 propensity-matched pairs of patients were generated, including 100 patients in the CTAG group and 200 patients in the Valiant Captivia group. RESULTS: Operative mortality were 2.33% (3 of 129) in the CTAG group and 1.76% (5 of 284) in the Valiant Captivia group. The median follow-up was 41.67 (26.00-60.67) months. No significant difference in mortality (9 [7.00%] vs. 36 [12.68%], P = 0.95) or re-intervention rate (3 [2.33%] vs. 20 [7.04%], P = 0.29) was observed between two groups. CTAG group have a lower incidence rate of distal stent graft-induced new entry tear than Valiant Captivia group (2.33% vs. 9.86%, P = 0.045). Lower incidence of type Ia endoleak was identified in the CTAG group (2.22%) than the Valiant Captivia group (14.41%) in patients with type III arch (P = 0.039). CONCLUSIONS: Both Valiant Captivia thoracic stent graft and CTAG thoracic endoprosthesis can be safely performed for acute TBAD with low operative mortality, favorable mid-term survival and freedom from reintervention. CTAG thoracic endoprosthesis had fewer dSINE even with larger oversizing and potentially suitable for type III arch with fewer type Ia endoleaks.