Long-Term Outcome of Aortic Dissection With Patent False Lumen

Discussing on the Aortic Coverage in Type B Aortic Dissection Treatment: A Comprehensive Scoping Review

OBJECTIVE

The objective of this study is to investigate and address the question surrounding the determination of the optimal endograft length of coverage during TEVAR for type B aortic dissection (TBAD), with a particular emphasis on the distal landing zone (DLZ).

DATA SOURCES

MEDLINE, Scopus, and Web of Science databases were used.

METHODS

The PRISMA-ScR statement was followed.

RESULTS

Several variables can contribute to the length of coverage during TEVAR in TBAD patient. Baseline patient's characteristics, TBAD-related features, the type of endoprosthesis, and postoperative graft behaviour may contribute to the choice of coverage.

CONCLUSIONS

No robust data have been published regarding the optimal length of TEVAR. Therefore, reporting the percentage of covered aorta and improving computational studies should be valorised to improve postoperative outcomes.

A Systematic Review and Meta-Analysis of Current Evidence Related to the Impact of Endovascular Repair Timing on Prognosis of Acute Stanford Type B Aortic Dissection

BACKGROUND

The objective of this study was to determine whether thoracic endovascular aortic repair (TEVAR) timing is more beneficial in the acute phase (first 14 days) than in the subacute phase (14-90 days) for the administration of acute Stanford type B aortic dissection (TBAD).

METHODS

A comprehensive literature search was conducted in databases (EMBASE, PubMed and Cochrane Library) until December 2023 to identify studies reporting the results of TEVAR used for patients with acute TBAD. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated utilizing either the random-effects model or the fixed-effects model.

RESULTS

A total of 25 studies involving 4,827 individuals with TBAD (including 1,609 with subacute TBAD) met our selection criteria. Early results revealed a lower incidence of Ia endoleaks (OR, 1.55; 95% CI, 1.03-2.33; P = 0.04) and aortic ruptures (OR, 2.89; 95% CI, 0.98-8.50; P = 0.05) in subacute TBAD. Apart from these findings, there was little difference in other incidents between the 2 groups. Regarding late outcomes, we observed significantly higher rates of retrograde dissection (OR, 2.12; 95% CI, 1.04-4.34; P = 0.04), distal stent-induced new entry (OR, 2.39; 95% CI, 1.24-4.61; P = 0.009), and reintervention (OR, 1.45; 95% CI, 0.05-1.99; P = 0.02) in acute TBAD than in subacute TBAD, whereas no significant differences were found for other outcomes between the 2 groups. Also, TEVAR appeared to yield comparable results for false lumen thrombosis and true lumen regression in both groups.

CONCLUSIONS

Subacute TBAD repair with TEVAR demonstrates a more effective reduction in adverse event rates compared to immediate treatment in the acute phase.

Postdissection aortic aneurysm sac enlargement after fenestrated and branched endovascular aortic aneurysm repair

OBJECTIVES

Aneurysm sac changes after fenestrated-branched endovascular aneurysm repair (FBEVAR) for postdissection thoracoabdominal aortic aneurysms (PD-TAAs) are poorly understood. Partial thrombosis of the false lumen and endoleaks may impair sac regression. To characterize sac changes after FBEVAR for PD-TAAs, this study examined midterm results and predictors for sac enlargement.

METHODS

FBEVARs performed for PD-TAAs in 10 physician-sponsored investigational device exemption studies from 2008 to 2023 were analyzed. The maximum aortic aneurysm diameter was compared between the 30-day computed tomography angiogram and follow-up imaging studies. Aneurysm sac enlargement was defined as an increase in diameter of ≥5 mm. Kaplan-Meier curves and Cox regression were used to evaluate sac enlargement and midterm FBEVAR outcomes.

RESULTS

Among 3296 FBEVARs, 290 patients (72.4% male; median age, 68.4 years) were treated for PD-TAAs. Most aneurysms treated were extent II (72%) and III (12%). Mean aneurysm diameter was 66.5 ± 11.2 mm. Mortality at 30 days was 1.4%. At a mean follow-up of 2.9 ± 1.9 years, at least one follow-up imaging study revealed sac enlargement in 43 patients (15%), sac regression in 115 patients (40%), and neither enlargement nor regression in 137 (47%); 5 (2%) demonstrated both expansion and regression during follow-up. Freedom from aneurysm sac enlargement was 93%, 82%, and 80% at 1, 3, and 5 years, respectively. Overall, endoleaks were detected in 27 patients (63%) with sac enlargement and 143 patients (58%) without enlargement (P = .54). Sac enlargement was significantly more frequent among older patients (mean age at the index procedure, 70.2 ± 8.9 years vs 66.5 ± 11 years; P = .04) and those with type II endoleaks at 1 year (74% vs 52%; P = .031). Cox regression revealed age >70 years at baseline (hazard ratio [HR], 2.146; 95% confidence interval [CI], 1.167-3.944; P = .010) and presence of type II endoleak at 1 year (HR, 2.25; 95% CI, 1.07-4.79; P = .032) were independent predictors of sac enlargement. Patient survival was 92%, 81%, and 68% at 1, 3, and 5 years, respectively. Cumulative target vessel instability was 7%, and aneurysm-related mortality was 2% at 5 years. At least 42% of patients required secondary interventions. Sac enlargement did not affect patient survival.

CONCLUSIONS

Aneurysm sac enlargement occurs in 15% of patients after FBEVAR for PD-TAAs. Elderly patients (>70 years at baseline) and those with type II endoleaks at 1 year may need closer monitoring and secondary interventions to prevent sac enlargement. Despite sac enlargement in some patients, aneurysm-related mortality at 5 years remains low and overall survival was not associated with sac enlargement.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Radiographic complicated and uncomplicated descending aortic dissections: aortic morphological differences by CT angiography and risk factor analysis

AIMS

To identify radiographic differences between patients with uncomplicated and complicated descending aortic dissections.

METHODS AND RESULTS

Between April 2009 and July 2021, 209 patients with acute descending aortic dissections were analysed as complicated (malperfusion, rupture, diameter progress, and diameter ≥ 55 mm) or uncomplicated. Detailed CTA measurements (slice thickness ≤ 3 mm) were taken in multiplanar reconstruction. A composite endpoint (early aortic failure) was defined as reoperation, diameter progression, and early mortality. Seventy-seven patients were female (36.8%) [complicated n = 27 (36.5%); uncomplicated n = 50 (37.0%) P = 1.00]. Seventy-four (35%) patients were categorized as morphologically complicated, and 135 (65%) as uncomplicated. In patients with complicated dissections, the dissection extended more frequently to the aortic bifurcation (P = 0.044), the coeliac trunk (P = 0.003), the superior mesenteric artery (P = 0.007), and both iliac arteries (P < 0.001) originated less frequently from the true lumen. The length of the most proximal communication (entry) in type B aortic dissection was longer, 14.0 mm [12.0 mm; 27.0 mm] vs. 6.0 mm [4,0 mm; 13.0 mm] in complicated cases (P = 0.005). Identified risk factors for adverse aortic events were connective tissue disease [HR 8.0 (1.9-33.7 95% CI HR)], length of the aortic arch [HR 4.7 (1.5-15.1 95% CI HR)], a false lumen diameter > 19.38 mm [HR 3.389 (1.1-10.2 95% CI HR)], and origin of the inferior mesenteric artery from the false lumen [HR 4.2 (1.0-5.5 95% CI HR)].

CONCLUSION

We identified significant morphological differences and predictors for adverse events in patients presenting complicated and uncomplicated descending dissections. Our morphological findings will help guide future aortic therapies, taking a tailored patient approach.

Complementary Thoracic Endovascular Aortic Repair (TEVAR) after Frozen Elephant Trunk for Residual Type A Aortic Dissection: Perioperative and Mid-Term Outcomes

Objectives: The aim of this retrospective study was to evaluate the results of complementary TEVAR following the frozen elephant trunk (FET) procedure for patients with residual type A aortic dissection (rTAAD) in terms of technical feasibility, safety and mid-term outcomes. Methods: This was a retrospective single-centre analysis of patients who received TEVAR after FET for rTAAD from January 2012 up to December 2021. The primary endpoint was technical success. Safety parameters included 30-day/in-hospital morbidity and mortality. Furthermore, mid-term clinical and morphological outcomes were evaluated. Results: Among 587 TEVAR procedures, 60 patients (11 with connective tissue disorders) who received TEVAR after FET for rTAAD were identified. The median interval between FET and TEVAR was 28.5 months. Indications for TEVAR after FET were true lumen collapse distal to FET prosthesis (n = 7), dSINE (n = 2), planned completion (n = 13) and aortic diameter progression (n = 38). In forty-seven patients, TEVAR was performed in an elective setting; eight and six patients were operated on in an urgent or emergency setting, respectively. All TEVAR procedures were successfully completed. The 30-day mortality and spinal cord ischemia rates were 1.7%. During a median follow-up of 37 months, two further patients died. Nine patients had to undergo a further aortic intervention: fenestrated stent-graft (n = 3) or open repair of the infrarenal abdominal aorta (n = 6). Conclusions: Complementary TEVAR following FET for rTAAD showed excellent technical success and low perioperative risk, supporting the feasibility and safety of this strategy. Despite the favourable mid-term survival, certain patients might require a further aortic procedure.

Predictors of Late Adverse Events in Patients with Surgically Treated Type I Aortic Dissection

OBJECTIVE

Residual aortic dissection (AD) following DeBakey type I AD repair is associated with a high rate of adverse events that need additional intervention or surgery. This study aimed to identify clinical and early post-operative computed tomography (CT) imaging factors associated with adverse events in patients with type I AD after ascending aorta replacement.

METHODS

This single centre, retrospective cohort study included consecutive patients with type I AD who underwent ascending aorta replacement from January 2011 to December 2017 and post-operative CT within three months. The primary outcome was AD related adverse events, defined as AD related death and re-operation due to aortic aneurysm or impending rupture. The location and size of the primary intimal tears, aortic diameter, and false lumen status were evaluated. Regression analyses were performed to identify factors associated with AD related adverse events. A decision tree model was used to classify patients as high or low risk.

RESULTS

Of 103 participants (55.43 ± 13.94 years; 49.5% male), 24 (23.3%) experienced AD related adverse events. In multivariable Cox regression analysis, connective tissue disease (hazard ratio [HR] 15.33; p < .001), maximum aortic diameter ≥ 40 mm (HR 4.90; p < .001), and multiple (three or more) intimal tears (HR 7.12; p < .001) were associated with AD related adverse events. The three year cumulative survival free from AD related events was lower in the high risk group with aortic diameter ≥ 40 mm and multiple intimal tears (41.7% vs. 90.9%; p < .001).

CONCLUSION

Early post-operative CT findings indicating a maximum aortic diameter ≥ 40 mm and multiple intimal tears may predict a higher risk of adverse events. These findings suggest the need for careful monitoring and more vigilant management approaches in these cases.

Three-year outcomes of the Dissected Aorta Repair Through Stent Implantation trial

OBJECTIVE

The study objective was to evaluate the clinical and radiographic outcomes of the Ascyrus Medical Dissection Stent in a prospective, nonrandomized, international study (Dissected Aorta Repair Through Stent Implantation) of patients with acute DeBakey type I aortic dissection.

METHODS

The Ascyrus Medical Dissection Stent was used in combination with the standard surgical management of acute DeBakey type I aortic dissection I to treat patients with (56.5%, 26/46) and without (43.5%, 20/46) preoperative clinical and radiographic malperfusion. All patients had a primary entry tear in the ascending aorta, and 97.8% (45/46) were treated with a hemiarch repair. Median follow-up was 3 years.

RESULTS

All 47 patients underwent emergency surgical repair with successful Ascyrus Medical Dissection Stent implantation. One patient was excluded from analysis due to use in iatrogenic dissection. Overall mortality at 30 days and 3 years was 13.0% (6/46) and 21.7% (10/46), respectively. Overall new stroke rate at 30 days was 15.2% (7/46). No devices were explanted at any time during the 3-year median follow-up. At 3 years, the total aortic diameter in zones 0, 1, and 2 decreased or remained stable in 91.7%, 72.7%, and 75.0%, respectively. The false lumen was completely or partially thrombosed in 90.5% in zone 0, 60.0% in zone 1, and 68.2% in zone 2 at 3 years.

CONCLUSIONS

The use of the Ascyrus Medical Dissection Stent in the treatment of acute DeBakey type I aortic dissection I holds promise as a simple technology that enables repair of the aortic arch and proximal descending aorta, while promoting positive aortic remodeling. Ongoing follow-up of the Dissected Aorta Repair Through Stent Implantation trial will provide long-term, prospective, clinical outcomes and radiographic data on positive remodeling of the aortic arch.

Evaluation and Utilization of Flow Artifacts at CT

Flow artifacts are commonly encountered at contrast-enhanced CT and can be difficult to discern from true pathologic conditions. Therefore, radiologists must be comfortable distinguishing flow artifacts from true pathologic conditions. This is of particular importance when evaluating the pulmonary arteries and aorta, as a flow artifact may be mistaken for a pulmonary embolism or dissection flap. Understanding the mechanics of flow artifacts and how these artifacts are created can help radiologists in several ways. First, this knowledge can help radiologists appreciate how the imaging characteristics of flow artifacts differ from true pathologic conditions. This information can also help radiologists better recognize the clinical conditions that predispose patients to flow artifacts, such as pneumonia, chronic lung damage, and altered cardiac output. By understanding when flow artifacts may be confounding the interpretation of an examination, radiologists can then know when to pursue other troubleshooting methods to assist with the diagnosis. In these circumstances, the radiologist can consider several troubleshooting methods, including adjusting the imaging protocols, recommending when additional imaging may be helpful, and suggesting which imaging study would be the most beneficial. Finally, flow artifacts can also be used as a diagnostic tool when evaluating the vascular anatomy, examples of which include the characterization of shunts, venous collaterals, intimomedial flaps, and alternative patterns of blood flow, as seen in extracorporeal membrane oxygenation circuits. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Preemptive treatment in the acute and early subacute phase of uncomplicated type B aortic dissections with poor prognosis factors

Objective

Due to its favorable outcome regarding late morbidity and mortality, thoracic endovascular repair (TEVAR) is becoming more popular for uncomplicated type B aortic dissection (TBAD). This study aimed to compare preemptive endovascular treatment and optimal medical treatment (OMT) and OMT alone in patients presenting uncomplicated TBAD with predictors of aortic progression.

Design

Retrospective multicenter study.

Methods

We analyzed patients with uncomplicated TBAD and risk factors of progression in two French academic centers. Aortic events [defined as aortic-related (re)intervention or aortic-related death after initial hospitalization], postoperative complications, non-aortic events, and radiologic aortic progression and remodeling were recorded and analyzed. Analysis was performed on an intention-to-treat basis.

Results

Between 2011 and 2021, preemptive endovascular procedures at the acute and early subacute phase (<30 days) were performed on 24 patients (group 1) and OMT alone on 26 patients (group 2). With a mean follow-up of 38.08 ± 24.53 months, aortic events occurred in 20.83% of patients from group 1 and 61.54% of patients from group 2 (p < .001). No patient presented aortic-related death during follow-up. There were no differences in postoperative events (p = 1.00) and non-aortic events (p = 1.00). OMT patients had significantly more aneurysmal progression of the thoracic aorta (p < .001) and maximal aortic diameter (p < .001). Aortic remodeling was found in 91.67% of patients in group 1 and 42.31% of patients in group 2 (p < .001). A subgroup analysis of patients in group 1 showed that patients treated with preemptive TEVAR and STABILISE had reduced maximum aortic diameters at the 1-year (p = .010) and last follow-up (p = .030) compared to those in patients treated with preemptive TEVAR alone.

Conclusion

Preemptive treatment of uncomplicated TBAD with risk factors of progression reduces the risk of long-term aortic events. Over 60% of medically treated patients will require intervention during follow-up, with no benefit in terms of postoperative events. Even after surgical treatment, patients in the OMT group had significantly more aneurysmal progression, along with poorer aortic remodeling.

The role of anatomic shape features in the prognosis of uncomplicated type B aortic dissection initially treated with optimal medical therapy

OBJECTIVE

Currently, the long-term outcomes of uncomplicated type B aortic dissection (TBAD) patients managed with optimal medical therapy (OMT) remain poor. Aortic expansion is a major factor that determines patient long-term survival. The objective of this study was to investigate the association between anatomic shape features and (i) OMT outcome; (ii) aortic growth rate for TBAD patients initially treated with OMT.

METHODS

108 CT images of TBAD in the acute and chronic phases were collected from 46 patients who were initially treated with OMT. Statistical shape models (SSM) of TBAD were constructed to extract shape features from the earliest initial CT scans of each patient by using principal component analysis (PCA) and partial least square (PLS) regression. Additionally, conventional shape features (e.g., aortic diameter) were quantified from the earliest CT scans as a baseline for comparison. We identified conventional and SSM features that were significant in separating OMT "success" and failure patients. Moreover, the aortic growth rate was predicted by SSM and conventional features using linear and nonlinear regression with cross-validations.

RESULTS

Size-related SSM and conventional features (mean aortic diameter: p=0.0484, centerline length: p=0.0112, PCA score c1: p=0.0192, and PLS scores t1: p=0.0004, t2: p=0.0274) were significantly different between OMT success and failure groups, but these features were incapable of predicting the aortic growth rate. SSM shape features showed superior results in growth rate prediction compared to conventional features. Using multiple linear regression, the conventional, PCA, and PLS shape features resulted in root mean square errors (RMSE) of 1.23, 0.85, and 0.84 mm/year, respectively, in leave-one-out cross-validations. Nonlinear support vector regression (SVR) led to improved RMSE of 0.99, 0.54, and 0.43 mm/year, for the conventional, PCA, and PLS features, respectively.

CONCLUSION

Size-related shape features of the earliest scan were correlated with OMT failure but led to large errors in the prediction of the aortic growth rate. SSM features in combination with nonlinear regression could be a promising avenue to predict the aortic growth rate.

The Use of the Ascyrus Medical Dissection Stent in Acute Type A Aortic Dissection Repair Reduces Distal Anastomotic New Entry Tear

BACKGROUND

A distal anastomotic new entry tear (DANE) can occur at the time of surgical repair for acute type A aortic dissection (ATAAD). This study aimed to compare the occurrence of DANE following a standard hemiarch repair with that following a hemiarch repair with an uncovered arch dissection stent.

METHODS

All patients who received a hemiarch repair or a hemiarch repair with an Ascyrus Medical Dissection Stent (AMDS) for ATAAD from 2017 to 2021 were included. Baseline and intra- and postoperative characteristics were collected. All available pre- and postoperative computed tomographic scans were analysed. The primary outcome measures were the incidence of DANE, positive aortic remodelling, mortality, and aortic reintervention rates at last follow-up.

RESULTS

A total of 114 patients underwent repair of Debakey I ATAAD during the study period with either an isolated hemiarch (n = 77) or a hemiarch with AMDS (n = 37). There was no significant difference in mortality (P = 0.768) or other in-hospital adverse events. During the follow-up period, DANE occurred in 43.3% (n = 26) of the isolated hemiarch group and in 11.8% (n = 4) of the hemiarch with AMDS group (P = 0.002). The incidence of false lumen thrombosis and obliteration favoured the AMDS group in the aortic arch (P = 0.029), the proximal descending thoracic aorta (P = 0.031), and level of pulmonary artery bifurcation (P = 0.044).

CONCLUSIONS

The incidence of DANE is significantly reduced with the addition of an AMDS at the time of hemiarch repair for ATAAD repair. Further follow-up is necessary to identify late aortic complications that may have been prevented by reducing the incidence of postoperative DANE.

Relationship between false lumen morphology and entry tear in acute type A aortic dissection

OBJECTIVES

This study aimed to investigate the relationship between false lumen morphology and the size, aortic segment and position of the entry tear for acute type A aortic dissection.

METHODS

The records of patients who underwent emergency operation for acute type A aortic dissection in our institution between April 2011 and May 2022 were examined. Data regarding size, location and position of the entry tear and preoperative computed tomography findings were reviewed. The relationship of these variables with false lumen morphology was examined and retrospectively compared according to tear size.

RESULTS

Of 243 cases, characteristics of the entry tear, visualized during surgery, were confirmed in 134 cases (age = 70.9 ± 12.6 years, male = 45.5%). Tear sizes at different aortic segments were not significantly different (P = 0.376). Tears posterior to the lesser curvature were significantly smaller than those anterior to the greater curvature (P = 0.004). A thrombosed false lumen was associated with a significantly smaller tear size and position on the posterior to the lesser curvature side in aortic cross-section (all P < 0.001). Multivariate analysis showed that tear size, the presence of re-entry and tear position anterior to the greater curvature were independent predictors of a patent false lumen.

CONCLUSIONS

In acute type A aortic dissection, larger tear size, the presence of re-entry and tear position anterior to the greater curvature are risk factors for a patent false lumen. Although the results of this study are valid only for patients in whom intimal tears were detected during aortic surgery, this trend may provide information for pathophysiology of the disease.

Prognostic Implications of Initial Focal Contrast Enhancement in Acute Type B Intramural Hematoma

BACKGROUND

The prognostic implication of initial focal contrast enhancement (FCE), including focal intimal disruption (FID) and intramural blood pool (IBP), in acute type B intramural hematoma (IMH) remain unclear.

OBJECTIVES

The purpose of this study was to compare the prognostic implications in IMH with or without FCE.

METHODS

A total of 574 patients were enrolled. FID was defined as an intimal disruption with contrast-filled out-pouching from the aorta lumen with a communicating orifice of >3 mm, and IBP was defined as a localized contrast medium-filled pool inside the IMH.

RESULTS

A total of 207 (36.1%) patients with initial FCE, including 132 (63.8%) FIDs and 75 (36.2%) IBPs, were identified. Patients with FCE accompanying IMH were more likely to have hypertension (P = 0.001), pleural effusion (P = 0.006), fewer aortic segments involved (P < 0.001), more adverse aortic events (AAEs) (P < 0.001), and fewer freedom from intervention (P = 0.002). Pleural effusion (HR: 1.79; 95% CI: 1.25-2.55; P = 0.001) and FCE (HR: 1.51; 95% CI: 1.12-2.02; P = 0.006) were identified to be the independent risk factors of AAEs. In the subgroup analysis, IMH with initial FID were more likely to progress than those with initial IBP (P < 0.001). FIDs located at the proximal descending aorta (HR: 2.95; 95% CI: 1.65-5.29; P < 0.001) were associated with AAEs.

CONCLUSIONS

Patients with FCE accompanying IMH were more likely to progress, especially in those initial FID localized at the proximal descending aorta. (Nature course and predictors of progression of intramural hematoma: A retrospective, multicenter study; ChiCTR2300073829).

Extensive thoracoabdominal aortic electro septotomy: A case report of a novel approach in the treatment of chronic aortic dissections

Treatment of post-dissection arch and thoracoabdominal aortic aneurysms presents significant therapeutic challenges. True lumen collapse or take off of aortic branches from the false lumen makes endograft alignment difficult, if not impossible. We present herein the first successful case of an extensive thoracoabdominal electro aortic septotomy of the entire dissection membrane from the aortic arch down to the aortic bifurcation during an open redo aortic arch replacement employing the frozen elephant trunk technique. The procedure was performed on a 59 years old female patient presenting with a progressive post-dissection aortic aneurysm during follow-up with a maximum diameter of 6 cm 11 years after operating on an acute type A aortic dissection. Due to the extensive longitudinal aortic electric septotomy, we created a new "common lumen" for subsequent endovascular completion of the repair.

A Systematic Review and an Updated Meta-Analysis of Fenestrated/Branched Endovascular Aortic Repair of Chronic Post-Dissection Thoracoabdominal Aortic Aneurysms

The objective of this study is to present the current outcomes of fenestrated/branched endovascular repair (F/BEVAR) for post-dissection thoracoabdominal aortic aneurysms (PDTAAAs). A systematic review of the literature according to PRISMA guidelines up to October 2023 was conducted (protocol CRD42023473403). Studies were included if ≥10 patients were reported and at least one of the major outcomes was stated. A total of 10 studies with 585 patients overall were included. The pooled estimate for technical success was 94.3% (95% CI 91.4% to 96.2%). Permanent paraplegia developed with a pooled rate of 2.5% (95% CI 1.5% to 4.3%), whereas a cerebrovascular event developed with a pooled rate of 1.6% (95% CI 0.8% to 3.0%). An acute renal function impairment requiring new-onset dialysis occurred with a pooled rate of 2.0% (95% CI 1.0% to 3.8%). Postoperative respiratory failure was observed with a pooled estimate of 5.5% (95% CI 3.8% to 8.1%). The pooled estimate for 12-month overall survival was 90% (95% CI 85% to 93.5%), and the pooled estimates for 24-month and 36-month survival were 87.8% (95% CI 80.9% to 92.5%) and 85.5% (95% CI 76.5% to 91.5%), respectively. Freedom from reintervention was estimated at 83.9% (95% CI 75.9% to 89.6%) for 12 months, 82.8% (95% CI 68.7% to 91.4%) for 24 months and 76.1% (95% CI 60.6% to 86.8%) for 36 months. According to the present findings, F/BEVAR can be performed in PD-TAAAs with high rates of technical success and good mid-term results.

Systemic immune-inflammation index predicts the clinical outcomes in patients with acute uncomplicated type-B aortic dissection undergoing optimal medical therapy

BACKGROUND

Optimal medical therapy (OMT) for uncomplicated type B aortic dissection (uTBAD) provides excellent short-term outcomes during follow up; however, its long-term therapeutic effectiveness is unsatisfactory. This study evaluated the predictive value of systemic immune-inflammation index (SII) for adverse events among patients with acute uTBAD undergoing OMT.

METHODS

We performed a retrospective analysis of a prospectively maintained database between 2013 and 2020. The primary end point in this study was composite outcomes including aortic intervention, all-cause mortality, retrograde type A aortic dissection (rTAAD) and aortic diameter growth > 5 mm. The patients were divided into high and low SII groups according to the optimal cut-off value of SII as determined using the receiver operating characteristic curve. Cox proportional hazards models were constructed to estimate the hazards ratios and identify the predictors of composite outcomes.

RESULTS

A total of 124 patients with acute uTBAD who underwent OMT were enrolled. One patient died during hospitalisation. At the end of a mean follow-up duration of 51 ± 23 months, 53 (43.1%) patients experienced composite outcomes, 15 patients (12.2%) died, 31 (25.2%) underwent aortic intervention, 21 (17.1%) exhibited diameter growth of > 5 mm, and 2 developed rTAAD. The patients were divided into low SII group (n = 78, 62.9%) and high SII group (n = 46, 37.1%) as per the optimal cut-off SII value of 1449. The incidence of composite outcomes in high SII group was significantly higher than that in low SII (28 [60.9%] vs. 26[33.3%], p < 0.01). Patients with high SII demonstrated significantly higher mortality rate than those with a low SII (11 [23.9%] vs. 5 [6.4%], respectively; p < 0.01). In addition, the high SII group had significantly higher rate of aortic-related reinterventions than the low SII group (16 [34.8%] vs. 15 [19.2%], p = 0.03). Multivariable Cox analyses showed that a high SII score was independently associated with composite outcomes rate (hazard ratio, 2.15; 95% confidence interval, 1.22-3.78; p < 0.01).

CONCLUSIONS

The long-term therapeutic effectiveness of OMT alone in patients with acute uTBAD is unsatisfactory. An SII > 1449 at the time of diagnosis is an independent predictor of OMT failure.

Hemodynamic effects of entry and exit tear size in aortic dissection evaluated with in vitro magnetic resonance imaging and fluid-structure interaction simulation

Understanding the complex interplay between morphologic and hemodynamic features in aortic dissection is critical for risk stratification and for the development of individualized therapy. This work evaluates the effects of entry and exit tear size on the hemodynamics in type B aortic dissection by comparing fluid-structure interaction (FSI) simulations with in vitro 4D-flow magnetic resonance imaging (MRI). A baseline patient-specific 3D-printed model and two variants with modified tear size (smaller entry tear, smaller exit tear) were embedded into a flow- and pressure-controlled setup to perform MRI as well as 12-point catheter-based pressure measurements. The same models defined the wall and fluid domains for FSI simulations, for which boundary conditions were matched with measured data. Results showed exceptionally well matched complex flow patterns between 4D-flow MRI and FSI simulations. Compared to the baseline model, false lumen flow volume decreased with either a smaller entry tear (- 17.8 and - 18.5%, for FSI simulation and 4D-flow MRI, respectively) or smaller exit tear (- 16.0 and - 17.3%). True to false lumen pressure difference (initially 11.0 and 7.9 mmHg, for FSI simulation and catheter-based pressure measurements, respectively) increased with a smaller entry tear (28.9 and 14.6 mmHg), and became negative with a smaller exit tear (- 20.6 and - 13.2 mmHg). This work establishes quantitative and qualitative effects of entry or exit tear size on hemodynamics in aortic dissection, with particularly notable impact observed on FL pressurization. FSI simulations demonstrate acceptable qualitative and quantitative agreement with flow imaging, supporting its deployment in clinical studies.

Type A aortic dissection: optimal annual case volume for surgery

BACKGROUND AND AIMS

The current study proposes a novel volume-outcome (V-O) meta-analytical approach to determine the optimal annual hospital case volume threshold for cardiovascular interventions in need of centralization. This novel method is applied to surgery for acute type A aortic dissection (ATAAD) as an illustrative example.

METHODS

A systematic search was applied to three electronic databases (1 January 2012 to 29 March 2023). The primary outcome was early mortality in relation to annual hospital case volume. Data were presented by volume quartiles (Qs). Restricted cubic splines were used to demonstrate the V-O relation, and the elbow method was applied to determine the optimal case volume. For clinical interpretation, numbers needed to treat (NNTs) were calculated.

RESULTS

One hundred and forty studies were included, comprising 38 276 patients. A significant non-linear V-O effect was observed (P < .001), with a notable between-quartile difference in early mortality rate [10.3% (Q4) vs. 16.2% (Q1)]. The optimal annual case volume was determined at 38 cases/year [95% confidence interval (CI) 37-40 cases/year, NNT to save a life in a centre with the optimal volume vs. 10 cases/year = 21]. More pronounced between-quartile survival differences were observed for long-term survival [10-year survival (Q4) 69% vs. (Q1) 51%, P < .01, adjusted hazard ratio 0.83, 95% CI 0.75-0.91 per quartile, NNT to save a life in a high-volume (Q4) vs. low-volume centre (Q1) = 6].

CONCLUSIONS

Using this novel approach, the optimal hospital case volume threshold was statistically determined. Centralization of ATAAD care to high-volume centres may lead to improved outcomes. This method can be applied to various other cardiovascular procedures requiring centralization.

Fate of the Patent False Lumen of the Descending Aorta After Surgical Treatment for Acute Type 1 Aortic Dissection

INTRODUCTION

This study aimed to investigate the factors affecting false lumen patency in the descending thoracic aorta among patients who underwent surgery for acute type 1 aortic dissection.

METHODS

A total of 112 patients with acute type 1 aortic dissection, with the flap below the diaphragm level, underwent surgery between January 2010 and September 2019. Of these, 60 patients who were followed up for ≥ 12 months and whose computed tomography scans were available were included in this study. The patients were divided into two groups: group I, consists of patent false lumen (n=36), and group II, consists of thrombosed false lumen (n=24). Demographic data, operative techniques, postoperative descending aortic diameters, reintervention, and late mortality were compared between the two groups.

RESULTS

The mean follow-up period of all patients was 37.6±26.1 months (range: 12-104). The diameter increase in the proximal and distal descending aorta was significantly higher in the patent false lumen group (5.3±3.7 mm vs. 3.25±2.34 mm; P=0.015; 3.1±2.52 mm vs. 1.9±1.55 mm; P=0.038, respectively). No significant difference in terms of hypertension was found between the two groups during the follow-up period (21 patients, 58.3% vs. 8 patients, 33.3%; P=0.058). A total of 29 patients (48.3%) were found to be hypertensive in the postoperative period.

CONCLUSION

After surgical treatment for acute type 1 aortic dissection, patients should be monitored closely, regardless of whether the false lumen is patent or thrombosed. Mortality and reintervention can be seen in patients with patent false lumen during follow-up.

A Comparison of Retrospective ECG-Gated CT and Surgical or Angiographical Findings in Acute Aortic Syndrome

The best cardiac phases in retrospective ECG-gated CT for detecting an intimal tear (IT) in aortic dissection (AD) and an ulcer-like projection (ULP) in an intramural hematoma (IMH) have not been established. This study aimed to compare the detection accuracy of diastolic-phase and systolic-phase ECG-gated CT for IT in AD and ULP in IMH, with subsequent surgical or angiographical confirmation as the reference standard.In total, 81 patients (67.6 ± 11.8 years; 41 men) who underwent emergency ECG-gated CT and subsequent open surgery or thoracic endovascular aortic repair for AD (n = 52) or IMH (n = 29) were included. The accuracies of detecting IT and ULP were compared among only diastolic-phase, only systolic-phase, and both diastolic-phase and systolic-phase methods of retrospective ECG-gated CT; surgical or angiographical findings were used as the reference standard. The detection accuracy for IT and ULP using only diastolic-phase, only systolic-phase, and both diastolic-phase and systolic-phase methods of ECG-gated CT was 93% [95% CI: 87-97], 94% [95% CI: 88-97], and 95% [95% CI: 90-97], respectively. There were no significant differences in detection accuracy among the 3 acquisition methods (P = 0.55). Similarly, there were no significant differences in the accuracy of detecting IT in AD (P = 0.55) and ULP in IMH (P > 0.99) among only diastolic-phase, only systolic-phase, and both diastolic- and systolic-phase ECG-gated CT.Retrospective ECG-gated CT for detecting IT in AD and ULP in IMH yields highly accurate findings. There were no significant differences seen among only diastolic-phase, only systolic-phase, and both diastolic-phase and systolic-phase ECG-gated CT.

Comparison of Short and Midterm Aortic Reinterventions in Acute Type A Aortic Dissection Treated by Frozen Elephant Trunk or Conventional Arch Repair

BACKGROUND

Long-term outcomes after acute type A aortic dissection (ATAAD) are related to remodelling of the descending thoracic aorta and aortic reinterventions. We compared the impact of an extensive repair at the index procedure using the Frozen Elephant Trunk (FET) technique, versus a conventional arch repair, on long-term remodelling of the descending thoracic and reintervention related to the aorta.

METHODS

Consecutive patients who underwent conventional arch repair (conventional group) or FET repair (FET group) for an ATAAD from September 2018 to November 2021 were included. Patients who died before discharge or were lost to follow-up prior to the first appointment were excluded from the analysis. Preoperative and postoperative computed tomography angiography was reconstructed and diameter of the true/false lumen of the remaining aorta was compared up to 1 year. Negative (increased total diameter ≥ 5 mm) aortic remodelling was collected for each computed tomography angiography, as well as aortic reinterventions. Comparison of demographic, anatomical, and perioperative complications data were performed using Wilcoxon test for continuous variables or Chi-square test for categorical covariates. The Kaplan-Meier method estimator was used to assess survival rates. The Log rank test was used to compare survival curves between the 2 groups.

RESULTS

Thirty nine patients were included, 22 in the conventional group and 17 in the FET group (82% males, mean age 60 ± 12 years). In the FET group, distal anastomosis was performed in zone 0 or 1 for 82% of patients using the simplified delivery technique. Median maximum preoperative descending aortic diameter was larger in the FET group (33 mm [30; 37] vs. 30 mm [28; 32] [P = 0.0172]). At 30 days, the rate of negative remodelling on the descending thoracic aorta was significantly higher in the conventional group (50%) than in the FET group (8%, P = 0.02). At 1 year, Kaplan-Meier analysis shown a freedom from descending aortic negative remodeling of 35.1% (95% confidence interval (CI) 18.7-66.1%) in conventional group and 44.9% (CI 95% 26.1-77.2%) in FET group with no significant difference. However, early negative remodelling was observed for the conventional group. Within a year, freedom from reintervention was observed for 74.4% (95% CI 57.1-97%) of patients in the conventional group and 75.5 (95% CI 57.1-99.7%) of patients in the FET group with no significant difference.

CONCLUSIONS

Negative evolution of descending aorta remains a challenge after ATAAD. An extensive repair using the FET technique during the index procedure seems to be associated with satisfying short-term remodelling of descending aorta.

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.

Descending thoracic aortic emergencies: Past, present, and future

The most important descending thoracic aortic (DTA) pathologies are aneurysms, dissections, and traumatic injuries. In acute settings, these conditions can constitute a significant risk of bleeding or ischemia of vital organs, resulting in a fatal outcome. Morbidity and mortality associated with aortic pathologies remain significant, despite improvements in medical therapy and endovascular techniques. In this narrative review, we present an overview of the transitions in the management of these pathologies and discuss current challenges and future perspectives. Diagnostic challenges include differentiating between thoracic aortic pathologies and cardiac diseases. Efforts have been made to identify a blood test that can rapidly differentiate these pathologies. Computed tomography is the cornerstone of diagnosing thoracic aortic emergencies. Our understanding of DTA pathologies has improved substantially due to the significant advancement in imaging modalities in the last 2 decades. On the basis of this understanding, the treatment of these pathologies has been revolutionized. Unfortunately, robust evidence from prospective and randomized studies is still lacking for the management of most DTA diseases. Medical management plays a crucial role in achieving early stability during these life-threatening emergencies. This includes intensive care monitoring, heart rate and blood pressure control, and considering permissive hypotension for patients presenting with ruptured aneurysms. Over the years, surgical management of DTA pathologies changed from open repair to endovascular repair with dedicated stent-grafts. Techniques in both spectrums have improved substantially.

ADSeg: A flap-attention-based deep learning approach for aortic dissection segmentation

Accurate and rapid segmentation of the lumen in an aortic dissection (AD) is an important prerequisite for risk evaluation and medical planning for patients with this serious condition. Although some recent studies have pioneered technical advances for the challenging AD segmentation task, they generally neglect the intimal flap structure that separates the true and false lumens. Identification and segmentation of the intimal flap may simplify AD segmentation, and the incorporation of long-distance z axis information interaction along the curved aorta may improve segmentation accuracy. This study proposes a flap attention module that focuses on key flap voxels and performs operations with long-distance attention. In addition, a pragmatic cascaded network structure with feature reuse and a two-step training strategy are presented to fully exploit network representation power. The proposed ADSeg method was evaluated on a multicenter dataset of 108 cases, with or without thrombus; ADSeg outperformed previous state-of-the-art methods by a significant margin and was robust against center variation.

Uncomplicated Type B Aortic Dissection: Challenges in Diagnosis and Categorisation

BACKGROUND

Acute type B aortic dissection (TBAD) is a rare disease that is likely under-diagnosed in the UK. As a progressive, dynamic clinical entity, many patients initially diagnosed with uncomplicated TBAD deteriorate, developing end-organ malperfusion and aortic rupture (complicated TBAD). An evaluation of the binary approach to the diagnosis and categorisation of TBAD is needed.

METHODS

A narrative review of the risk factors predisposing patients to progression from unTBAD to coTBAD was undertaken.

RESULTS

Key high-risk features predispose the development of complicated TBAD, such as maximal aortic diameter > 40 mm and partial false lumen thrombosis.

CONCLUSION

An appreciation of the factors that predispose to complicated TBAD would aid clinical decision-making surrounding TBAD.

Preoperative Predictors of Late Aortic Expansion in Acute Type B Aortic Dissection Treated with TEVAR

BACKGROUND

A patent false lumen (FL) in patients with thoracic endovascular aortic repair (TEVAR)-treated type B aortic dissection (TBAD) can cause a significant risk for late aortic expansion (LAE). We hypothesize that preoperative features can predict the occurrence of LAE.

METHODS

Sufficient preoperative and postoperative follow-up clinical and imaging feature data for patients treated with TEVAR in the First Affiliated Hospital of Nanjing Medical University from January 2018 to December 2020 were collected. A univariate analysis and multivariable logistic regression analysis were used to find potential risk factors of LAE.

RESULTS

Ninety-six patients were finally included in this study. The mean age was 54.5 ± 11.7 years and 85 (88.5%) were male. LAE occurred in 15 (15.6%) of 96 patients after TEVAR. Two preoperative factors showed strong associations with LAE according to the multivariable logistic regression analysis: preoperative partial thrombosis of the FL (OR = 10.989 [2.295-48.403]; p = 0.002) and the maximum descending aortic diameter (OR = 1.385 [1.100-1.743] per mm increase; p = 0.006).

CONCLUSIONS

Preoperative partial thrombosis of the FL and an increase in the maximum aortic diameter are strongly associated with late aortic expansion. Additional interventions of the FL may help to improve the prognosis of patients with the high risk of late aortic expansion.

Early Thoracic Endovascular Aortic Repair of Uncomplicated Type B Thoracic Aortic Dissection: An Aorta Team Approach

BACKGROUND

 Although uncomplicated Type B aortic dissection (uTBAD) is traditionally treated with optimal medical therapy (OMT) as per guidelines, recent studies, performed primarily in interventional radiology or surgical operating rooms, suggest superiority of thoracic endovascular aortic repair (TEVAR) over OMT due to recent advancements in endovascular technologies. We report a large, single-center, case control study of TEVAR versus OMT in this population, undertaken solely in a cardiac catheterization laboratory (CCL) with a cardiologist and surgeon. We aimed to determine if TEVAR for uTBAD results in better outcomes compared with OMT.

METHODS

 This was a retrospective chart review of all patients with uTBAD during the last 13 years, with 46 cases (TEVAR group) and 56 controls (OMT group).

RESULTS

 In the TEVAR group, the procedure duration of 2.5 hours resulted in 100% procedural success for stent placement, with 63% undergoing protective left subclavian artery bypass, 0% mortality or stroke, and a lower readmission rate (1 vs. 2%; p = 0.04 in early TEVAR cases), but a longer length of stay (12.9 vs. 8.5 days: p = 0.006). The risk of all-cause long-term mortality was markedly reduced in the TEVAR group (RR = 0.38; p = 0.01), irrespective of early (<14 days) versus late intervention. On follow-up computed tomography imaging, the false lumen stabilized or decreased in 85% of cases, irrespective of intervention timing.

CONCLUSION

 TEVAR performed solely in the CCL is safe and effective, with lower all-cause mortality than OMT. These data, in collaboration with previous data on TEVAR in different settings, call for consideration of an update of practice guidelines.

Acute aortic dissection: evidence, uncertainties, and future therapies

Remarkable progress has become especially apparent in aortic medicine in the last few decades, leading to essential changes in how thoracic aortic dissection is understood and treated. This state-of-the-art review article addresses the mechanisms of acute aortic dissection, explaining the role of its primary entry location, proximal, and distal dissection extension in their clinical presentation and impact on the decision-making process towards the best treatment approach. The latest evidence on novel treatment methods for acute aortic syndromes is presented, and the diverse dissection classification systems that remain uncertain are discussed, which reveals the need for shared terminology and more clarity. Finally, future aspects are discussed in treating acute aortic dissection, such as the endovascular treatment of aortic dissection Type A and biomarkers for acute aortic syndromes.

Acute aortic dissection

Although substantial progress has been made in the prevention, diagnosis, and treatment of acute aortic dissection, it remains a complex cardiovascular event, with a high immediate mortality and substantial morbidity in individuals surviving the acute period. The past decade has allowed a leap forward in understanding the pathophysiology of this disease; the existing classifications have been challenged, and the scientific community moves towards a nomenclature that is likely to unify the current definitions according to morphology and function. The most important pathophysiological pathway, namely the location and extension of the initial intimal tear, which causes a disruption of the media layer of the aortic wall, together with the size of the affected aortic segments, determines whether the patient should undergo emergency surgery, an endovascular intervention, or receive optimal medical treatment. The scientific evidence for the management and follow-up of acute aortic dissection continues to evolve. This Seminar provides a clinically relevant overview of potential prevention, diagnosis, and management of acute aortic dissection, which is the most severe acute aortic syndrome.

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.

The Role of Multimodality Imaging Approach in Acute Aortic Syndromes: Diagnosis, Complications, and Clinical Management

Acute aortic syndromes are life-threatening conditions with high morbidity and mortality. The principal pathological feature is acute wall damage with possible evolution towards aortic rupture. Accurate and timely diagnosis is mandatory to avoid catastrophic consequences. Indeed, misdiagnosis with other conditions mimicking acute aortic syndromes is associated with premature death. In this view, cardiovascular imaging is necessary for the correct diagnosis and management. Echocardiography, computed tomography, magnetic resonance imaging, and aortography allow for diagnosis, guarantee immediate treatment, and detect associated complications. Multimodality imaging is essential in the diagnostic work-up to confirm or rule out acute aortic syndromes. The aim of this review is to highlight the contemporary evidence on the role of single cardiovascular imaging techniques and multimodality imaging in the diagnosis and management of acute aortic syndromes.

Inter-observer variability of expert-derived morphologic risk predictors in aortic dissection

OBJECTIVES

Establishing the reproducibility of expert-derived measurements on CTA exams of aortic dissection is clinically important and paramount for ground-truth determination for machine learning.

METHODS

Four independent observers retrospectively evaluated CTA exams of 72 patients with uncomplicated Stanford type B aortic dissection and assessed the reproducibility of a recently proposed combination of four morphologic risk predictors (maximum aortic diameter, false lumen circumferential angle, false lumen outflow, and intercostal arteries). For the first inter-observer variability assessment, 47 CTA scans from one aortic center were evaluated by expert-observer 1 in an unconstrained clinical assessment without a standardized workflow and compared to a composite of three expert-observers (observers 2-4) using a standardized workflow. A second inter-observer variability assessment on 30 out of the 47 CTA scans compared observers 3 and 4 with a constrained, standardized workflow. A third inter-observer variability assessment was done after specialized training and tested between observers 3 and 4 in an external population of 25 CTA scans. Inter-observer agreement was assessed with intraclass correlation coefficients (ICCs) and Bland-Altman plots.

RESULTS

Pre-training ICCs of the four morphologic features ranged from 0.04 (-0.05 to 0.13) to 0.68 (0.49-0.81) between observer 1 and observers 2-4 and from 0.50 (0.32-0.69) to 0.89 (0.78-0.95) between observers 3 and 4. ICCs improved after training ranging from 0.69 (0.52-0.87) to 0.97 (0.94-0.99), and Bland-Altman analysis showed decreased bias and limits of agreement.

CONCLUSIONS

Manual morphologic feature measurements on CTA images can be optimized resulting in improved inter-observer reliability. This is essential for robust ground-truth determination for machine learning models.

KEY POINTS

• Clinical fashion manual measurements of aortic CTA imaging features showed poor inter-observer reproducibility. • A standardized workflow with standardized training resulted in substantial improvements with excellent inter-observer reproducibility. • Robust ground truth labels obtained manually with excellent inter-observer reproducibility are key to develop reliable machine learning models.

Monitoring of false lumen thrombosis in type B aortic dissection by impedance cardiography - A multiphysics simulation study

Aortic dissection is caused by a tear on the aortic wall that allows blood to flow through the wall layers. Usually, this tear involves the intimal and partly the medial layer of the aortic wall. As a result, a new false lumen develops besides the original aorta, denoted then as the true lumen. The local hemodynamic conditions such as flow disturbances, recirculations and low wall shear stress may cause thrombus formation and growth in the false lumen. Since the false lumen status is a significant predictor for late-dissection-related deaths, it is of great importance in the medical management of patients with aortic dissection. The hemodynamic changes in the aorta also alter the electrical conductivity of blood. Since the blood is much more conductive than other tissues in the body, such changes can be identified with non-invasive methods such as impedance cardiography. Therefore, in this study, the capability of impedance cardiography in monitoring thrombosis in the false lumen is studied by multiphysics simulations to assist clinicians in the medical management of patients under treatment. To tackle this problem, a 3D computational fluid dynamics simulation has been set up to model thrombosis in the false lumen and its impact on the blood flow-induced conductivity changes. The electrical conductivity changes of blood have been assigned as material properties of the blood-filled aorta in a 3D finite element electric simulation model to investigate the impact of conductivity changes on the measured impedance from the body's surface. The results show remarkable changes in the electrical conductivity distribution in the measurement region due to thrombosis in the false lumen, which significantly impacts the morphology of the impedance cardiogram. Thus, frequent monitoring of impedance cardiography signals may allow tracking the thrombus formation and growth in the false lumen.

Readmission after early thoracic endovascular aortic repair versus medical management of acute type B aortic dissection

BACKGROUND

The use of thoracic endovascular aortic repair (TEVAR) for the management of acute uncomplicated type B aortic dissection (TBAD) has increased. Although the results from early studies were promising, larger randomized trials evaluating TEVAR are lacking. It is also unclear where sufficient equipoise exists for such trials. In the present study, we evaluated the number of readmissions and unplanned operations after TEVAR vs those after medical management as the initial treatment of acute uncomplicated TBAD and the frequency of each treatment in this population.

METHODS

We performed a multi-institutional retrospective review of patients with acute TBAD from 2015 to 2020 with the 1-year outcomes available, excluding patients with prior aortic intervention or chronic, iatrogenic or traumatic etiologies. The primary exposure was TEVAR vs medical management at the index admission. The patient demographics, clinical presentation, and imaging findings were analyzed using bivariate and multivariate logistic regression for the primary outcomes of unplanned readmission and/or operation after the initial admission. The secondary outcomes were mortality, myocardial infarction, stroke, renal failure requiring dialysis, retrograde type A dissection, and length of stay. We hypothesized that the readmissions would be higher with medical management.

RESULTS

A total of 216 patients with TBAD (47 with complicated and 169 with uncomplicated) from two large academic centers were identified. Of the 169 patients with uncomplicated TBAD, 83 (49%) had been treated medically and 86 (51%) had undergone TEVAR at the initial admission. No differences were found in the demographics or high-risk imaging features at presentation. The medically managed patients had had higher rates of unplanned readmission (34% vs 9%; P = .0001) and operation (28% vs 8%; P = .0007) but shorter lengths of stay (6.3 vs 13.1 days; P < .0001). No differences were found in mortality, although the rate of myocardial infarction was higher in the medically managed group (10.8% vs 2.3%; P = .02). Although 28% of the medically managed patients had later required operation, they had had morbidity and mortality similar to those of patients who had undergone initial TEVAR. Initial medical management was associated with unplanned readmission (odds ratio, 8.3; P = .02) and the need for operation (odds ratio, 4.56; P = .006). No differences were found in the outcomes according to the involved aortic zones.

CONCLUSIONS

In the present study, medical management of acute uncomplicated TBAD was associated with higher rates of readmission and the need for unplanned operation compared with TEVAR. However, no differences were found in the 1-year mortality for the patients for whom medical management had failed. Because one half of the patients had undergone medical management and one half had undergone early TEVAR, this finding suggests clinical equipoise for the treatment of acute uncomplicated TBAD. Therefore, a larger randomized trial appears warranted to determine whether a clear benefit exists for early TEVAR.

Morphological parameters affecting false lumen thrombosis following type B aortic dissection: a systematic study based on simulations of idealized models

Type B aortic dissection (TBAD) carries a high risk of complications, particularly with a partially thrombosed or patent false lumen (FL). Therefore, uncovering the risk factors leading to FL thrombosis is crucial to identify high-risk patients. Although studies have shown that morphological parameters of the dissected aorta are related to FL thrombosis, often conflicting results have been reported. We show that recent models of thrombus evolution in combination with sensitivity analysis methods can provide valuable insights into how combinations of morphological parameters affect the prospect of FL thrombosis. Based on clinical data, an idealized geometry of a TBAD is generated and parameterized. After implementing the thrombus model in computational fluid dynamics simulations, a global sensitivity analysis for selected morphological parameters is performed. We then introduce dimensionless morphological parameters to scale the results to individual patients. The sensitivity analysis demonstrates that the most sensitive parameters influencing FL thrombosis are the FL diameter and the size and location of intimal tears. A higher risk of partial thrombosis is observed when the FL diameter is larger than the true lumen diameter. Reducing the ratio of the distal to proximal tear size increases the risk of FL patency. In summary, these parameters play a dominant role in classifying morphologies into patent, partially thrombosed, and fully thrombosed FL. In this study, we point out the predictive role of morphological parameters for FL thrombosis in TBAD and show that the results are in good agreement with available clinical studies.

In situ visualization of aortic dissection propagation in notched rabbit aorta using synchrotron X-ray tomography

Aortic dissection is a complex, intramural, and dynamic condition involving multiple mechanisms, hence, difficult to observe. In the present study, a controlled in vitro aortic dissection was performed using tension-inflation tests on notched rabbit aortic segments. The mechanical test was combined with conventional (cCT) and synchrotron (sCT) computed tomography for in situ imaging of the macro- and micro-structural morphological changes of the aortic wall during dissection. We demonstrate that the morphology of the notch and the aorta can be quantified in situ at different steps of the aortic dissection, and that the notch geometry correlates with the critical pressure. The phenomena prior to propagation of the notch are also described, for instance the presence of a bulge at the tip of the notch is identified, deforming the remaining wall. Finally, our method allows us to visualize for the first time the propagation of an aortic dissection in real-time with a resolution that has never previously been reached. STATEMENT OF SIGNIFICANCE: With the present study, we investigated the factors leading to the propagation of aortic dissection by reproducing this mechanical process in notched rabbit aortas. Synchrotron CT provided the first visualisation in real-time of an aortic dissection propagation with a resolution that has never previously been reached. The morphology of the intimal tear and aorta was quantified at different steps of the aortic dissection, demonstrating that the early notch geometry correlates with the critical pressure. This quantification is crucial for the development of better criteria identifying patients at risk. Phenomena prior to tear propagation were also described, such as the presence of a bulge at the tip of the notch, deforming the remaining wall.

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.

Imaging surveillance for complications after primary surgery for type A aortic dissection

Acute type A aortic dissection (ATAAD) is a life-threatening condition that requires emergency surgery to avert fatal outcome. Conventional surgical procedures comprise excision of the entry tear and replacement of the proximal aorta with a synthetic vascular graft. In patients with DeBakey type I dissection, this approach leaves a chronically dissected distal aorta, putting them at risk for progressive dilatation, dissection propagation and aortic rupture. Therefore, ATAAD survivors should undergo serial imaging for evaluation of the aortic valve, proximal and distal anastomoses, and the aortic segments beyond the distal anastomosis. The current narrative review aims to describe potential complications in the early and late phases after ATAAD surgery, with focus on their specific imaging findings.

Shear-driven modelling of thrombus formation in type B aortic dissection

Background: Type B aortic dissection (TBAD) is a dangerous pathological condition with a high mortality rate. TBAD is initiated by an intimal tear that allows blood to flow between the aortic wall layers, causing them to separate. As a result, alongside the original aorta (true lumen), a false lumen (FL) develops. TBAD compromises the whole cardiovascular system, in the worst case resulting in complete aortic rupture. Clinical studies have shown that dilation and rupture of the FL are related to the failure of the FL to thrombose. Complete FL thrombosis has been found to improve the clinical outcomes of patients with chronic TBAD and is the desired outcome of any treatment. Partial FL thrombosis has been associated with late dissection-related deaths and the requirement for re-intervention, thus the level of FL thrombosis is dominant in classifying the risk of TBAD patients. Therefore, it is important to investigate and understand under which conditions complete thrombosis of the FL occurs.

Method: Local FL hemodynamics play an essential role in thrombus formation and growth. In this study, we developed a simplified phenomenological model to predict FL thrombosis in TBAD under physiological flow conditions. Based on an existing shear-driven thrombosis model, a comprehensive model reduction study was performed to improve computational efficiency. The reduced model has been implemented in Ansys CFX and applied to a TBAD case following thoracic endovascular aortic repair (TEVAR) to test the model. Predicted thrombus formation based on post-TEVAR geometry at 1-month was compared to actual thrombus formation observed on a 3-year follow-up CT scan.

Results: The predicted FL status is in excellent agreement with the 3-year follow-up scan, both in terms of thrombus location and total volume, thus validating the new model. The computational cost of the new model is significantly lower than the previous thrombus model, with an approximate 65% reduction in computational time. Such improvement means the new model is a significant step towards clinical applicability.

Conclusion: The thrombosis model developed in this study is accurate and efficient at predicting FL thrombosis based on patient-specific data, and may assist clinicians in choosing individualized treatments in the future.

Systematic total arch replacement with thoraflex hybrid graft in acute type A aortic dissection: A single centre experience

Introduction

In the last two decades, a more aggressive approach has been encouraged to treat patients with acute type A aortic dissection (ATAAD), extending the repair to the aortic arch and proximal descending thoracic aorta with the frozen elephant trunk (FET) implantation. Here, we report our single-centre experience with the FET technique for the systematic treatment of emergency type A aortic dissection.

Materials and methods

Between December 2017 and January 2022, 69 consecutive patients were admitted with ATAAD; of those, 66 patients (62.9 ± 10.2 years of age, 81.8% men) underwent emergency hybrid aortic arch and FET repair with the multibranched Thoraflex hybrid graft and were enrolled in the study. Primary endpoints were 30 days- and in-hospital mortality. Secondary endpoints were postoperative morbidity and follow-up survival. To better clarify the impact of age on surgical outcomes, we have divided the study population into two groups: group A for patients <70 years of age (47 patients), and group B for patients ≥70 years (19 patients). Time-to-event analysis has been conducted using the Log-rank test and is displayed with Kaplan-Meier curves. A multiple Cox proportional Hazard model was developed to identify predictors of long-term survival with a stepwise backward/forward selection process.

Results

30-days- and in-hospital mortality were 10.6 and 13.6%, respectively. Stroke occurred in three (4.5%) patients. Two (3.0%) patients experienced spinal cord ischemia. We did not find any statistically significant difference between the two groups in terms of main post-operative outcomes. The multivariable Cox proportional hazard model showed left ventricular ejection fraction (HR: 0.83, 95% CI: 0.79–0.92, p < 0.01), peripheral vascular disease (HR: 15.8, 95% CI: 3.9–62.9, p < 0.01), coronary malperfusion (HR: 0.10, 95% CI: 0.01–0.77, p =0.03), lower limbs malperfusion (HR: 5.1, 95% CI: 1.10–23.4, p = 0.04), and cardiopulmonary bypass time (HR: 1.02, 95% CI: 1–1.04, p = 0.01) as independent predictors of long term mortality.

Conclusions

Frozen elephant trunk repair to treat emergency type A aortic dissection appears to be associated with good early and mid-term clinical outcomes even in the elderly.

Volume Analysis to Predict the Long-Term Evolution of Residual Aortic Dissection after Type A Repair

Background: The aim of this study was to evaluate the aortic diameter and volume during the first year after a type A repair to predict the long-term prognosis of a residual aortic dissection (RAD). Methods: All patients treated in our center for an acute type A dissection with a RAD and follow-up > 3 years were included. We defined two groups: group 1 with dissection-related events (defined as an aneurysmal evolution, distal reintervention, or aortic-related death) and group 2 without dissection-related events. The aortic diameters and volume analysis were evaluated on three postoperative CT scans: pre-discharge (T1), 3−6 months (T2) and 1 year (T3). Results: Between 2009 and 2016, 54 patients were included. Following a mean follow-up of 75.4 months (SD 31.5), the rate of dissection-related events was 62.9% (34/54). The total aortic diameters of the descending thoracic aorta were greater in group 1 at T1, T2 and T3, with greater diameters in the FL (p < 0.01). The aortic diameter evolution at 3 months was not predictive of long-term dissection-related events. The total thoracic aortic volume was significantly greater in group 1 at T1 (p < 0.01), T2 (p < 0.01), and T3 (p < 0.01). At 3 months, the increase in the FL volume was significantly greater in group 1 (p < 0.01) and was predictive for long-term dissection-related events. Conclusion: This study shows that an initial CT scan volume analysis coupled with another at 3 months is predictive for the long-term evolution in a RAD. Based on this finding, more aggressive treatment could be given at an earlier stage.

Thoracic Endovascular Aortic Repair for Chronic Type B Aortic Dissection: Pre- and Postprocedural Imaging

Aortic dissection is a chronic disease that requires lifelong clinical and imaging surveillance, long after the acute event. Imaging has an important role in prognosis, timing of repair, device sizing, and monitoring for complications, especially in the endovascular therapy era. Important anatomic features at preprocedural imaging include the location of the primary intimal tear and aortic zonal and branch vessel involvement, which influence the treatment strategy. Challenges of repair in the chronic phase include a small true lumen in conjunction with a stiff intimal flap, complex anatomy, and retrograde perfusion from distal reentry tears. The role of thoracic endovascular aortic repair (TEVAR) remains controversial for treatment of chronic aortic dissection. Standard TEVAR is aimed at excluding the primary intimal tear to decrease false lumen perfusion, induce false lumen thrombosis, promote aortic remodeling, and prevent aortic growth. In addition to covering the primary intimal tear with an endograft, several adjunctive techniques have been developed to mitigate retrograde false lumen perfusion. These techniques are broadly categorized into false lumen obliteration and landing zone optimization strategies, such as the provisional extension to induce complete attachment (PETTICOAT), false lumen embolization, cheese-wire fenestration, and knickerbocker techniques. Familiarity with these techniques is important to recognize expected changes and complications at postintervention imaging. The authors detail imaging options, provide examples of simple and complex endovascular repairs of aortic dissections, and highlight complications that can be associated with various techniques. Online supplemental material is available for this article. ^©RSNA, 2022.