Volumetric analysis of type B aortic dissections treated with thoracic endovascular aortic repair

Mid-term Outcomes of Thoracic Endovascular Aortic Repair (TEVAR) in Acute Complicated Type B Aortic Dissection: A Comprehensive Analysis of Aortic Remodeling Patterns

Purpose

This study provides a comprehensive analysis of the clinical outcomes associated with endovascular treatment for acute complicated type B aortic dissection, with a focus on the complex process of aortic remodeling.

Materials and Methods

We conducted a retrospective investigation using data extracted from the Songklanagarind Hospital database between January 2010 and January 2022. Electronic medical records of patients who underwent thoracic endovascular aortic repair (TEVAR) for acute complicated type B aortic dissections were reviewed. The analysis focused on in-hospital outcomes, overall survival, aorta-related survival, reintervention-free survival, and changes in aortic lumen diameter to assess aortic remodeling.

Results

Over the study period, 32 patients with acute complicated type B aortic dissections underwent TEVAR. The in-hospital mortality rate was 9.4%, with complications occurring in 21.9% of patients. Temporary acute kidney injury was observed in 9.4% of the cases, wound bleeding in 6.3%, pneumonia in 6.3%, and permanent spinal cord ischemia in 3.1%. Re-intervention was necessary in 6.3% of cases. The overall survival rates at 6 months, 1 year, 3 years, and 6 years were 78%, 75%, 65%, and 44%, respectively. Aorta-related survival rates were 87%, 87%, 83%, and 75% at the corresponding time intervals. The reintervention-free survival rates were 96%, 96%, 71%, and 71%, respectively. Survival analysis revealed that patients with ideal aortic remodeling experienced the most favorable outcomes, whereas those with undesirable aortic remodeling exhibited the least favorable survival. Notably, undesirable pattern of aortic remodeling emerged as a singular factor with a statistically significant influence on predicting survival (hazard ratio 4.37, P-value=0.021).

Conclusion

TEVAR resulted in favorable aorta-related survival outcomes. Notably, the identification of changes in aortic lumen diameter alongside false lumen thrombosis, encapsulated within the framework of aortic remodeling patterns, has emerged as a robust predictor of post-TEVAR survival outcomes.

Optimal medical treatment versus endovascular aortic repair in uncomplicated isolated abdominal aortic dissection

OBJECTIVE

To report the results of optimal medical treatment (OMT) and endovascular aortic repair (EVAR) in patients with uncomplicated isolated abdominal aortic dissection (IAAD).

METHODS

A retrospective review of 96 consecutive patients with uncomplicated IAAD (uIAAD) managed at a single tertiary vascular unit between January 2011 and July 2021 was conducted. Standard methods for univariate and survival analyses were used. The primary outcomes were all-cause mortality. Secondary end points included uIAAD progression, interventional complications, and follow-up aortic intervention.

RESULTS

Initially, 53.1% of patients (51/96) were managed with OMT. No in-hospital deaths occurred. During follow-up, three patients died, and three and two patients who were initially managed with OMT subsequently required endovascular treatment and surgical management, respectively. Initially, 46.9% of patients (45/96) underwent EVAR. One patient died during hospital admission; nine patients had an endoleak after operation and one needed reintervention. Furthermore, during follow-up, five patients died; four patients needed reoperation, one surgery and three endovascular treatments. The overall long-term mortality was 8.4%, and follow-up aortic intervention rate was 9.5% (median follow-up, 54 months; interquartile range, 33-81 months) with no significant difference between groups. Of note, 12 patients (12.6%) suffered uIAAD progression, which was higher in the OMT group than EVAR group (10 [19.6%] vs 2 [4.5%]; P = .03).

CONCLUSIONS

uIAAD may be managed safely by OMT with regular surveillance, despite the risk of disease progression. Compared with OMT, EVAR could significantly prevent uIAAD progression. For anatomically suitable patients with uIAAD progression and who are unresponsive to OMT, pre-emptive EVAR is a safe and feasible option.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Long-Term Aortic Remodeling After Thoracic Endovascular Aortic Repair of Acute, Subacute, and Chronic Type B Dissections

Objective

This study aimed to investigate the characteristics and predictors of aortic remodeling over a long-term follow-up period after thoracic endovascular aortic repair (TEVAR) for acute, subacute, and chronic type B aortic dissections (TBADs).

Methods

Patients who underwent TEVAR for TBAD from July 2011 to December 2013 were included, and relevant data were retrospectively analyzed.

Results

After TEVAR, the true lumen (TL) dimension increased and the false lumen (FL) dimension decreased or did not change over a 5-year follow-up period in all three temporal groups. Shrinkage proportion of the thoracic aorta was the highest in the subacute group (acute, 28.1%; subacute, 39.1%; and chronic, 17.4%; p = 0.048), while abdominal expansion showed no significant differences among the groups (acute, 29.6%; subacute, 40.5%; and chronic, 44.4%; p = 0.502). The chronic group had a rate of complete FL regression, which is lower than the subacute or acute group at all anatomic sections, with significant differences only in the stented section (chronic, 21.7%; acute, 92.2%; and subacute, 80.4%; p < 0.05) and in the distal thoracic aortic section (chronic, 13.0%; acute, 31.1%; and subacute, 50.0%; p < 0.05). Logistic regression analysis demonstrated that chronic dissection, TL compression, endoleak, the number of branches from FL, and the number of residual tears affected optimal FL remodeling.

Conclusion

The present study provides data on aortic remodeling of TBAD after TEVAR during a long-term follow-up period. The features and risk factors of aortic remodeling in the acute, subacute, and chronic phases are different in different aortic segments. These findings may have implications in the timing of TEVAR.

1-Year Outcomes of a Multicenter Randomized Controlled Trial of the Ankura II Thoracic Endoprosthesis for the Endovascular Treatment of Stanford Type B Aortic Dissections

Background

The Ankura II Thoracic Stent Graft System (Lifetech, Shenzhen, China) is an evolution of the Ankura stent graft. This study reports one-year outcomes of the Ankura II Thoracic Stent Graft System for endovascular treatment of Stanford type B aortic dissections.

Methods

The Ankura II Thoracic Aortic Endovascular Trial was a randomized, single-blinded, clinical trial conducted at 12 Chinese institutes. The enrolled patients diagnosed with Stanford type B aortic dissections (TBADs) were randomly assigned to the Ankura group or Ankura II group. Standard follow-up examinations were performed at 1, 6, and 12 months. Safety and efficacy data were analyzed.

Results

132 patients with TBADs were enrolled. The outcomes for the primary safety end points revealed that the Ankura II stent graft was statistically non-inferior compared to the Ankura stent graft. The 1-month device-related major adverse events (1.6 vs. 0%; p = 0.48), 1-month all-cause mortality (1.7 vs. 4.5%; p = 0.621), 12-month survival rate (95.2 ± 2.7% vs. 94.1 ± 2.9%; p = 0.769), and major adverse event (MAE) rate (5.1 vs. 4.7% at 1 month; p = 0.73 and 5.8 vs. 8.9% at 12 months; p = 0.718) of Ankura II group are all comparable to Ankura group. The two groups showed similar primary effectiveness and true lumen expansion effect, and false lumen remodeling was improved in Ankura II group (−100.0 vs. −48.5%; p = 0.08).

Conclusions

The one-year outcomes from this prospective, randomized, multicenter study demonstrate that Ankura II stent graft shows comparable results to Ankura for treating TBADs, resulting in low mortality rates, MAEs and reintervention rates.

Clinical Trial Registration

ChiCTR-TRC-12002844.

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

Background

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

Aims

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

Methods

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

Results

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

Conclusion

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

An adaptive optimal viewing angle determination algorithm for TEVAR operation

BACKGROUND

The determination of the right x-ray angiography viewing angle is an important issue during the treatment of thoracic endovascular aortic repair (TEVAR). An inaccurate projection angle (manually determined today by the physicians according to their personal experience) may affect the placement of the stent and cause vascular occlusion or endoleak.

METHODS

Based on the acquisition of a computed tomography angiography (CTA) image before TEVAR, an adaptive optimization algorithm is proposed to determine the optimal viewing angle of the angiogram automatically. This optimal view aims at avoiding any overlapping between the left common carotid artery and the left subclavian artery. Moreover, the proposed optimal procedure exploits the patient-specific morphology to adaptively reduce the potential foreshortening effect.

RESULTS

Experimental results conducted on thirty-five patients demonstrate that the optimal angiographic viewing angle based on the proposed method has no significant difference when compared with the expert practice (p = 0.0678).

CONCLUSION

We propose a method that utilizes the CTA image acquired before TEVAR to automatically calculate the optimal C-arm angle. This method has the potential to assist surgeons during their interventional procedure by providing a shorter procedure time, less radiation exposure, and less contrast injection.

Distal Aortic Remodeling after Type A Dissection Repair: An Ongoing Mirage

Remodeling is a commonly encountered term in the field of cardiothoracic surgery that is often used to describe various pathophysiological changes in the dimension, structure, and function of various cardiac chambers, including the aorta. Stanford type A or DeBakey type 1 aortic dissection (TAAD) is a perplexing pathologic condition that can present surgical teams with the need to navigate a maze of complex decision-making. Ascending or hemi-arch replacement leaves behind a significant amount of distal diseased aortic tissue, which might have a persistent false lumen or primary or secondary intimal tears (or communications between lumina), which can lead to dilatation of the aortic arch. Unfavorable aortic remodeling is a major cause of distal aortic deterioration after the index surgery. Cardiac surgeons are aware of post-surgical cardiac chamber remodeling, but the concept of distal aortic remodeling is still idealized. The contemporary literature from established aortic centers supports aggressive management of the residual aortic pathology during the index surgery, and with continuing technical advancements, endovascular stenting options are readily available for patients with TAAD or for complicated type B aortic dissection cases. This review discusses the pathophysiology and treatment options for favorable distal aortic remodeling, as well as its impact on mid- to long-term outcomes following TAAD repair.

TEVAR for complicated and uncomplicated type B aortic dissection-Systematic review and meta-analysis

BACKGROUND

Type B aortic dissection (TBAD), is defined as a dissection involving the aorta distal to left subclavian artery with the ascending aorta and the aortic arch not affected. TBAD is classified due to the time frame and presence of complications. Complicated TBAD (co-TBAD) patients have a greater mortality rate than uncomplicated TBAD (un-TBAD) and thoracic endovascular aortic repair (TEVAR) is considered the gold-standard intervention for these clinical challenges.

METHODS

We undertook a systematic review of the literature regarding TEVAR intervention in co-TBAD and un-TBAD. A comprehensive search was undertaken across four major databases and was evaluated and assessed until June 2020.

RESULTS

A total of 16,104 patients were included in the study (7772 patients co-TBAD and 8352 un-TBAD). A significantly higher proportion of comorbidities were seen in co-TBAD patients compared with un-TBAD. Acute dissection was more frequent in the co-TBAD group (73.55% vs. 66.91%), while chronic dissection was more common in un-TBAD patients (33.8% vs. 70.73%). Postprocedure stroke was higher in co-TBAD (5.85% vs. 3.92%; p < .01), while postprocedural renal failure was higher in un-TBAD patients (7.23 vs. 11.38%; p < .01). No difference was observed in in-hospital mortality however the 30 days mortality was higher in the co-TBAD group. One-year survival was higher in the uncomplicated group but this difference was not observed in the 5-year survival.

CONCLUSION

In our analysis we can appreciate that despite significantly higher comorbidities in the co-TBAD cohort, there was no difference in in-hospital mortality between the two groups and the 5-year survival did not have any difference.

Comparison of diametric and volumetric changes in Stanford type B aortic dissection patients in assessing aortic remodeling post-stent graft treatment

Background

The study aims to analyze the correlation between the maximal diameter (both axial and orthogonal) and volume changes in the true (TL) and false lumens (FL) after stent-grafting for Stanford type B aortic dissection.

Method

Computed tomography angiography was performed on 13 type B aortic dissection patients before and after procedure, and at 6 and 12 months follow-up. The lumens were divided into three regions: the stented area (Region 1), distal to the stent graft to the celiac artery (Region 2), and between the celiac artery and the iliac bifurcation (Region 3). Changes in aortic morphology were quantified by the increase or decrease of diametric and volumetric percentages from baseline measurements.

Results

At Region 1, the TL diameter and volume increased (pre-treatment: volume =51.4±41.9 mL, maximal axial diameter =22.4±6.8 mm, maximal orthogonal diameter =21.6±7.2 mm; follow-up: volume =130.7±69.2 mL, maximal axial diameter =40.1±8.1 mm, maximal orthogonal diameter =31.9+2.6 mm, P<0.05 for all comparisons), while FL decreased (pre-treatment: volume =129.6±150.5 mL; maximal axial diameter =43.0±15.8 mm; maximal orthogonal diameter =28.3±12.6 mm; follow-up: volume =66.6±95.0 mL, maximal axial diameter =24.5±19.9 mm, maximal orthogonal diameter =16.9±13.7, P<0.05 for all comparisons). Due to the uniformity in size throughout the vessel, high concordance was observed between diametric and volumetric measurements in the stented region with 93% and 92% between maximal axial diameter and volume for the true/false lumens, and 90% and 92% between maximal orthogonal diameter and volume for the true/false lumens. Large discrepancies were observed between the different measurement methods at regions distal to the stent graft, with up to 46% differences between maximal orthogonal diameter and volume.

Conclusions

Volume measurement was shown to be a much more sensitive indicator in identifying lumen expansion/shrinkage at the distal stented region.

3D Morphologic Findings Before and After Thoracic Endovascular Aortic Repair for Type B Aortic Dissection

BACKGROUND

Stanford type-B aortic dissection (TBAD) is commonly treated by thoracic endovascular aortic repair (TEVAR). Usually, the implanted stent-grafts will not cover the entire dissection-affected region for those patients with dissection extending beyond the thoracic aorta, thus the fate of the uncovered aortic segment is uncertain. This study used 3-dimensional measurement of aortic morphological changes to classify the different remodeling effects of TBAD patients after TEVAR, and hypothesized that not only initial morphological features, but also their change over time at follow-up are associated with the remodeling.

METHODS

Forty-one TBAD patients underwent TEVAR and CT-angiography before and after the intervention (twice or more follow-ups) were included in this study. According to the false-lumen volume variations post-TEVAR, patients who had abdominal aortic expansion at the second follow-up were classified into the Enlarged (n =12, 29%) and remaining into the Stable group (n = 29, 71%). 3D morphological parameters were extracted on precise reconstruction of imaging datasets. Statistical differences in 3D morphological parameters over time between the 2 groups and the relationship among these parameters were analyzed.

RESULTS

In the Enlarged group, the number of all tears before TEVAR was significantly higher (P = 0.022), and the size of all tears at the first and second follow-up post-TEVAR were significantly higher than that in the Stable group (P = 0.008 and P = 0.007). The location of the primary tear was significantly higher (P = 0.031) in the Stable group. The cross-sectional analysis of several slices below the primary tear before TEVAR shows different shape features of the false lumen in the Stable (cone-like) and Enlarged (hourglass-like) groups. The number of tears before TEVAR has a positive correlation with the post-TEVAR development of dissection (r = 0.683, P = 0.00).

CONCLUSION

The results in this study indicated that the TBAD patients with larger tear areas, more re-entry tears and with the primary tear proximal to the arch would face a higher risk of negative remodeling after TEVAR.

Critical appraisal of multidimensional CT measurements following acute open repair of type A aortic dissection

INTRODUCTION

To identify patients with aneurysmal degeneration of the native aorta following type A aortic dissection (TAAD), reproducible serial measurements of aortic dimensions are critical. We used a systematic workflow for measuring aortic geometry following TAAD, using computed tomography angiography data, and test its reproducibility.

METHODS

The workflow for aortic measurements included centerline generation, luminal diameter, and area measurement at six anatomically defined locations along the aorta and luminal volumetric measurements in the descending aorta. Two independent observers measured the aortic geometry in 20 surgically repaired TAAD patients, preoperatively and at 3 months follow-up. To test reproducibility, intraobserver and interobserver agreement scores were analyzed using a concordance correlation coefficient (CCC).

RESULTS

The interobserver agreement scores of the diameter, area, and volumetric measurements in the descending aorta were acceptable. The agreement scores of the area measurements were highest, with CCCs ranging from 0.909 to 0.984. Luminal diameter measurements scored lower than luminal area measurements and were least reproducible at the mid aortic arch (CCC < 0.886). Overall, intraobserver agreement scores were better than interobserver agreement scores (SD of mean difference was 1.89 vs 1.94 for intraobserver vs interobserver diameter measurements, and 0.61 vs 0.66 for area measurements).

CONCLUSION

Although overall reproducibility was acceptable in descending aortic measurements, our results show that it remains challenging to reliably measure luminal diameters, compared with areas. To aid identification of early adverse remodeling following acute TAAD, novel two- and three-dimensional measurement techniques are needed that capture locoregional changes in the false lumen and true lumen morphology more accurately.

Endovascular Therapy for Chronic Type B Aortic Dissection

Objectives: Endovascular repair of the thoracic aorta (TEVAR) represents a therapeutic option for type B aortic dissection. However, the optimal timing for TEVAR is controversial. We examined the outcomes of TEVAR for chronic type B dissection and reviewed aortic morphology using pre- and postoperative CT scan images.

Methods: Between 2012 and 2017, 12 patients underwent TEVAR for chronic type B dissection at our institution. We retrospectively reviewed the clinical and operative data including CT scan images, comparing the values between early group (5 cases, 3 months to 1 year from initial dissection) and late group (7 cases, more than 1 year from initial dissection).

Results: There were no paraplegia, stroke, and death in our cohort. There was no difference in degree of the aortic remodeling between two groups.

Conclusions: Outcomes after TEVAR for chronic type B aortic dissection were favorable. Aortic remodeling could be obtained in selected patients by closing an entry with TEVAR procedure. (This is a translation of Jpn J Vasc Surg 2018; 27: 281–287.)

Expanded Petticoat technique to promote the reduction of contrasted false lumen volume in patients with chronic type B aortic dissection

OBJECTIVE

This study examined the outcomes of our novel concept of expanded provisional extension to induce complete attachment strategy (Petticoat) for safety, durability, and remodeling of chronic type B dissections.

METHODS

Twenty patients with chronic type B aortic dissection with aneurysmal degeneration qualified for an expanded Petticoat strategy (stent graft in the thoracic, plus additional distal bare stent into the abdominal and infrarenal aorta, followed by parallel stent grafts into common iliac arteries). Computed tomography was performed preoperatively and at 1, 6, and 12 months after surgery.

RESULTS

The primary technical success was 100%. The 30-day mortality rate was 0%. At 12 months, favorable aortic remodeling and complete false lumen (FL) thrombosis were noted as 100% in the thoracic and infrarenal aorta. The volume of contrast-enhanced FL decreased from 186 ± 75.4 mL all along the dissection preoperatively (range, 70-360 mL), to 6.32 ± 5.4 mL postoperatively (range, 0.0-19.6 mL) and was only observed in the visceral aorta (P = .000089). Despite persistent flow in a small area of the FL, the maximal aortic size was stable in follow-up. Neither paraplegia nor visceral branch occlusion were noted in the follow-up.

CONCLUSIONS

The treatment of aortic dissections with an expanded Petticoat strategy seems to be safe and offers good early results. It significantly reduced the volume of contrast enhanced FL. Further investigation of any subsequent results will be necessary.

Thoracic endovascular aortic repair with stent grafts alone or with a composite device design in patients with acute type B aortic dissection in the setting of malperfusion

OBJECTIVE

The objective of this study was to compare short-term outcomes in patients who underwent thoracic endovascular aortic repair (TEVAR) with stent grafts alone or with a composite device design (stent graft plus bare-metal aortic stent) for acute type B aortic dissection in the setting of malperfusion.

METHODS

This retrospective analysis included patients with acute (≤14 days of symptom onset) complicated type B dissection in the setting of malperfusion who were treated with stent grafts alone (TEVAR cohort) at two European institutions vs those who underwent TEVAR with a composite device design (Cook Medical, Bloomington, Ind) in the investigational STABLE I feasibility study and STABLE II pivotal study (STABLE cohort). Preoperative characteristics and 30-day outcomes (including mortality, malperfusion-related mortality, morbidity, and secondary interventions) were compared between the two groups.

RESULTS

The TEVAR cohort (41 patients; mean age, 58.8 ± 12.7 years; 78.0% male) and the STABLE cohort (84 patients; mean age, 57.8 ± 11.7 years; 71.4% male) were largely similar in preoperative medical characteristics, with more STABLE patients presenting with a history of hypertension (79.8% vs 58.5%; P = .018). The TEVAR and STABLE groups had similar lengths of dissection (451.8 ± 112.7 mm vs 411.8 ± 116.4 mm; P = .10) and similar proximal and distal extent of dissection. At presentation, the two groups exhibited comparable organ system involvement in malperfusion: renal (53.7% TEVAR, 57.1% STABLE), gastrointestinal (41.5% TEVAR, 44.0% STABLE), lower extremities (34.1% TEVAR, 52.4% STABLE), and spinal cord (9.8% TEVAR, 2.4% STABLE). The 30-day rate of all-cause mortality was 17.1% (7/41) in the TEVAR group and 8.3% (7/84) in the STABLE group (P = .22). The 30-day rate of malperfusion-related mortality (deaths from bowel/mesenteric ischemia or multiple organ failure) was 12% (5/41) in the TEVAR group and 2.4% (2/84) in the STABLE group (P = .038). The 30-day morbidity, for the TEVAR and STABLE groups, respectively, included bowel ischemia (9.8% [4/41] vs 2.4% [2/84]; P = .09), renal failure requiring dialysis (7.3% [3/41] vs 9.5% [8/84]; P > .99), paraplegia or paraparesis (4.9% [2/41] vs 3.6% [3/84]; P = .66), and stroke (2.4% [1/41] vs 10.7% [9/84]; P = .16). The occurrence of 30-day secondary intervention was similar in the TEVAR and STABLE groups (7.3% [3/41] vs 7.1% [6/84]; P > .99). True lumen expansion in the abdominal aorta was significantly greater in the STABLE group.

CONCLUSIONS

In patients with acute type B aortic dissection in the setting of branch vessel malperfusion, the use of a composite device with proximal stent grafts and distal bare aortic stent appeared to result in lower malperfusion-related mortality than the use of stent grafts alone. The 30-day rates of morbidity and secondary interventions were similar between the groups.

Implications of secondary aortic intervention after thoracic endovascular aortic repair for acute and chronic type B dissection

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) has become a mainstay of therapy for acute and chronic type B aortic dissection (TBAD). Dynamic aortic morphologic changes, untreated dissected aorta, and persistent false lumen perfusion have significant consequences for reintervention after TEVAR for TBAD. However, few reports contrast differences in secondary aortic intervention (SAI) after TEVAR for TBAD or describe their influence on mortality. This analysis examined incidence, timing, and types of SAI after TEVAR for acute and chronic TBAD and determined their impact on survival.

METHODS

All TEVAR procedures for acute and chronic TBAD (2005-2016) were retrospectively reviewed. Patients with staged (<30 days) or concomitant ascending aortic arch repair or replacement were excluded. Acuity was defined by symptom onset (0-30 days, acute; >30 days, chronic). SAI procedures were grouped into open (intended treatment zone or remote aortic site), major endovascular (TEVAR extension or endograft implanted at noncontiguous site), and minor endovascular (side branch or false lumen embolization) categories. Kaplan-Meier methodology was used to estimate freedom from SAI and survival. Cox proportional hazards were used to identify SAI predictors.

RESULTS

TEVAR for TBAD was performed in 258 patients (acute, 49% [n = 128]; chronic, 51% [n = 130]). Mean follow-up was 17 ± 22 months with an overall SAI rate of 27% (n = 70; acute, 22% [28]; chronic, 32% [42]; odds ratio, 1.7; 95% confidence interval, 0.9-2.9; P = .07]. Median time to SAI was significantly less after acute than after chronic dissection (0.7 [0-12] vs 7 [0-91] months; P < .001); however, freedom from SAI was not different (1-year: acute, 67% ± 4%, vs chronic, 68% ± 5%; 3-year: acute, 65% ± 7%, vs chronic, 52% ± 8%; P = .7). Types of SAI were similar (acute vs chronic: open, 61% vs 55% [P = .6]; major endovascular, 36% vs 38% [P = .8]; minor endovascular, 21% vs 21% [P = 1]). The open conversion rate (either partial or total endograft explantation: acute, 10% [13/128]; chronic, 15% [20/130]; P = .2) and incidence of retrograde dissection (acute, 6% [7/128]; chronic, 4% [5/130]; P = .5) were similar. There was no difference in survival for SAI patients (5-year: acute + SAI, 55% ± 9%, vs acute without SAI, 67% ± 8% [P = .3]; 5-year: chronic + SAI, 72% ± 6%, vs chronic without SAI, 72% ± 7% [P = .7]). Factors associated with SAI included younger age, acute dissection with larger maximal aortic diameter at presentation, Marfan syndrome, and use of arch vessel adjunctive procedures with the index TEVAR. Indication for the index TEVAR (aneurysm, malperfusion, rupture, and pain or hypertension) or remote preoperative history of proximal arch procedure was not predictive of SAI.

CONCLUSIONS

SAI after TEVAR for TBAD is common. Acute TBAD has a higher proportion of early SAI; however, chronic TBAD appears to have ongoing risk of remediation after the first postoperative year. SAI types are similar between groups, and the occurrence of aorta-related reintervention does not affect survival. Patients' features and anatomy predict need for SAI. These data should be taken into consideration for selection of patients, device design, and surveillance strategies after TEVAR for TBAD.

Flow pattern analysis in type B aortic dissection patients after stent-grafting repair: Comparison between complete and incomplete false lumen thrombosis

Endovascular stent graft repair has become a common treatment for complicated Stanford type B aortic dissection to restore true lumen flow and induce false lumen thrombosis. Using computational fluid dynamics, this study reports the differences in flow patterns and wall shear stress distribution in complicated Stanford type B aortic dissection patients after endovascular stent graft repair. Five patients were included in this study: 2 have more than 80% false lumen thrombosis (group 1), while 3 others had less than 80% false lumen thrombosis (group 2) within 1 year following endovascular repair. Group 1 patients had concentrated re-entry tears around the abdominal branches only, while group 2 patients had re-entry tears that spread along the dissection line. Blood flow inside the false lumen which affected thrombus formation increased with the number of re-entry tears and when only small amounts of blood that entered the false lumen exited through the branches. In those cases where dissection extended below the abdominal branches (group 2), patients with fewer re-entry tears and longer distance between the tears had low wall shear stress contributing to thrombosis. This work provides an insight into predicting the development of complete or incomplete false lumen thrombosis and has implications for patient selection for treatment.

Vascular Deformation Mapping (VDM) of Thoracic Aortic Enlargement in Aneurysmal Disease and Dissection

Thoracic aortic aneurysm is a common and lethal disease that requires regular imaging surveillance to determine timing of surgical repair and prevent major complications such as rupture. Current cross-sectional imaging surveillance techniques, largely based on computed tomography angiography, are focused on measurement of maximal aortic diameter, although this approach is limited to fixed anatomic positions and is prone to significant measurement error. Here we present preliminary results showing the feasibility of a novel technique for assessing change in aortic dimensions, termed vascular deformation mapping (VDM). This technique allows quantification of 3-dimensional changes in the aortic wall geometry through nonrigid coregistration of computed tomography angiography images and spatial Jacobian analysis of aortic deformation. Through several illustrative cases we demonstrate that this method can be used to measure changes in the aortic wall geometry among patients with stable and enlarging thoracic aortic aneurysm and dissection. Furthermore, VDM results yield observations about the presence, distribution, and rate of aortic wall deformation that are not apparent by routine clinical evaluation. Finally, we show the feasibility of superposing patient-specific VDM results on a 3-dimensional aortic model using color 3D printing and discuss future directions and potential applications for the VDM technique.

A novel anatomic severity grading score for acute Type B aortic dissections and correlation to aortic reinterventions after thoracic endovascular aortic repair

Background

We introduce a novel preoperative anatomic severity grading system for acute type B aortic dissections and validate the system in a cohort of patients who underwent thoracic endovascular aortic repair.

Methods

We identified a cohort of patients who received thoracic endovascular aortic repair (TEVAR) for acute type B aortic dissection from 2008 to 2014. We developed an anatomic severity grading score (ASG) to measure attributes of aortic anatomy that we hypothesized may affect difficulty or durability of repair. Measurements were made using computed tomography angiography images and based on hypothesized severity, giving a potential score range of 0-38.

Results

We analyzed the computed tomography angiography images on a cohort of 30 patients with acute type B aortic dissection who underwent TEVAR. We created an area under the receiver operating characteristic curve (AUROC) using anatomic severity grading to predict aortic-related reinterventions. The AUROC was 0.72 (95% CI 0.39 to 1.1). Guided by the AUROC, we divided patients into two groups: a low-score group with anatomic severity grading scores <23 (n = 22), and a high-score group with scores ≥23 (n = 8). With this cutoff, anatomic severity grading exhibited 80% sensitivity and 84% specificity in predicting aortic-related reinterventions, with reinterventions in 50% of high-score patients and 4.5% of low-score patients (P = 0.011). The high score group also had significantly greater blood loss (200 vs 100 mL, P = 0.038), fluoroscopy time (36.0 vs 16.6 min; P = 0.022), and a trend for increased procedure time (164 vs 95 min; P = 0.083) than the low-risk group. Kaplan-Meier analysis revealed that the high-score group had a significantly decreased freedom from aortic-related reinterventions than the low-score group (38% vs 100% at 12-month followup; log rank P = 0.001).

Conclusions

A preoperative anatomic severity grading score for acute type B aortic dissections consists of analysis of the proximal landing zone, curvature and tortuosity of the aorta, dissection anatomy, aortic branch vessel anatomy, and supraceliac aorta anatomy. Anatomic severity grading scores ≤23 are an excellent predictor of aortic-related reinterventions.

Endovascular management of chronic symptomatic aortic dissection with the Streamliner Multilayer Flow Modulator: Twelve-month outcomes from the global registry

OBJECTIVE

Reported are initial 12-month outcomes of patients with chronic symptomatic aortic dissection managed by the Streamliner Multilayer Flow Modulator (SMFM; Cardiatis, Isnes, Belgium). Primary end points were freedom from rupture- and aortic-related death, and reduction in false lumen index. Secondary end points were patency of great vessels and visceral branches, and freedom of stroke, paraplegia, and renal failure.

METHODS

Out of 876 SMFM implanted globally, we have knowledge of 542. To date, 312 patients are maintained in the global registry, of which 38 patients were identified as having an aortic dissection (12.2%). Indications included 35 Stanford type B dissections, two Stanford type A and B dissections, and one mycotic Stanford type B dissection.

RESULTS

There were no reported ruptures or aortic-related deaths. All cause survival was 85.3% Twelve-month freedom from neurologic events was 100%, and there were no incidences of end-organ ischemia, paraplegia or renal insult. Morphologic analysis exhibited dissection remodeling by a reduction in longitudinal length of the dissected aorta, and false lumen volume. A statistically significant reduction in false lumen index (P = .016) at 12 months, and a borderline significant increase in true lumen volume (P = .053) confirmed dissection remodeling.

CONCLUSIONS

The SMFM is an option in management of complex pan-aortic dissection. Results highlight SMFM implantation leads to dissection stabilization with no further aneurysm progression, and no retrograde type A dissection. Thoracic endovascular aneurysm repair by SMFM ensued in freedom from aortic rupture, neurologic stroke, paraplegia and renal failure. Further analysis of the global registry data will inform long-term outcomes.

Aortic Remodeling Following Sun's Procedure for Acute Type A Aortic Dissection

Background

Sun’s procedure is a surgical technique widely used in type A aortic dissection. The purpose of this study was to analyze clinical outcomes and morphologic changes in true and false lumen by computed tomography (CT) angiography after Sun’s procedure.

Material/Methods

We retrospectively reviewed 51 patients who underwent Sun’s procedure for acute Stanford type A aortic dissection extending down to iliac bifurcation between January 2013 and December 2014. The images of preoperative, one-month, three-month, and six-month follow-up were analyzed by CT angiography to measure the area and diameter of true and false lumen.

Results

Four patients died before surgical intervention and postoperative deaths occurred in five patients (in-hospital mortality rate 10.6%). Only 42 patients (36 male, 6 female; mean age, 45.9±9.8 years; range, 24–65 years) with acute type A aortic dissection were involved in our study. Thirty-five patients (83.3%) suffered from chest or abdominal pain and only one patient (2.4%) was asymptomatic. Thirty-seven patients (88.1%) had hypertension as the most common comorbidity. In the ascending aorta, false lumen was eliminated and the change of true lumen was not significant (p>0.05). In the descending aorta, complete and partial thrombosis of false lumen were observed in eight patients (19.0%) and 33 patients (78.6%) by one-month follow-up CT scan, respectively. After the six-month follow-up, the rate of complete thrombosis increased to 36.1% and partial thrombosis decreased to 61.9%. The area and maximal diameter of true lumen were increased significantly (p<0.05), whereas significant decreases were found in the area and maximal diameter of false lumen (p<0.05). In the abdominal aorta, thrombosis was found in 52.4% patients at one-month follow-up CT. Furthermore, there were no significant changes in both true and false lumen within three months (p>0.05). Nevertheless, the false luminal area and maximal diameter decreased significantly (p<0.05) after six months, while these changes of true lumen were not significant (p>0.05).

Conclusions

After Sun’s procedure, aortic remodeling was a continuous process and occurred in a predictable model, and the extent of aortic remodeling varied at different levels. Remodeling in descending thoracic aorta was earlier than it was in abdominal aorta.

Influence of distal entry tears in acute type B aortic dissection after thoracic endovascular aortic repair

OBJECTIVE

This study evaluated the clinical influence of distal entry tears in acute type B aortic dissection (ATBAD) after thoracic endovascular aortic repair (TEVAR).

METHODS

From August 2009 to December 2014, the clinical outcomes of 130 patients who underwent TEVAR for ATBAD were retrospectively analyzed. According to whether distal entry tears existed after TEVAR, patients were divided into group A (n = 25, absence of distal entry tears) and group B (n = 105, presence of distal entry tears). We evaluated clinical outcomes, including mortality and morbidity in early and late follow-up, as well as aortic remolding. Late aortic events were defined as aortic dissection-related events occurring >30 days from the initial TEVAR procedures, which consisted of endoleak, retrograde type A aortic dissection, aortic enlargement, late rupture, repeat dissection, and stent-induced new entry tear.

RESULTS

The study comprised 130 patients (114 men [87.7%] and 16 women [12.3%)] with a mean age of 53.71 years. The 30-day mortality was 3.1%, and early morbidity included type I endoleak, 3.1%, organ failure, 3.8%; stroke, 3.1%; spinal cord ischemia, 0%; and early rupture 1.5%. The overall survival rate by Kaplan-Meier analysis at 1, 3, and 5 years was 93.8%, 89.5%, and 79.2%, respectively. There were no significant differences in early morbidity and 30-day mortality and late survival between group A and group B. However, group A had a significantly lower rate of late aortic events than group B (P = .028 by log-rank test). Meanwhile, group A had better aortic remolding than group B in complete thrombosis of the thoracic aorta at 12 months postoperatively (100% vs 83.5%; P = .029).

CONCLUSIONS

This study demonstrated that TEVAR for ATBAD had low perioperative morbidity and mortality and satisfactory midterm outcome. Distal entry tears increase the occurrence of late aortic events and inhibit aortic remolding but do not have a significantly negative effect on late survival. Repairing all entry tears to restore single-lumen blood flow and enhance false lumen thrombosis might benefit selected patients.

Volumetric analysis demonstrates that true and false lumen remodeling persists for 12 months after thoracic endovascular aortic repair

A 62-year-old man underwent an elephant trunk procedure followed by thoracic endovascular aortic repair (TEVAR). Computed tomography angiography-based models were built to quantify volume of the whole aorta and true and false lumens preoperatively, before TEVAR, after TEVAR, and at follow-up at 3, 6, and 12 months. With TEVAR, descending aortic true lumen volume increased by 54%, then increased additionally by 60% during 12 months. The descending aortic false lumen volume regressed continuously for 12 months following TEVAR, with the most rapid rate from 6 to 12 months at 16 cm3/month. TEVAR immediately increased true lumen volume and continued to remodel the true and false lumens throughout the following 12 months.

Frequency of abdominal aortic expansion after thoracic endovascular repair of type B aortic dissection

Purpose

To determine abdominal aortic expansion after thoracic endovascular aortic repair (TEVAR) in patients with aortic dissection type B and 36 months minimum follow-up.

Methods

Retrospective study of 18 TEVAR patients with follow-up >36 months. Abdominal aortic diameters at celiac trunk (location B) and infrarenal aorta (location C) were recorded on the first and last imaging after TEVAR. False lumen thrombosis was determined at level of endograft (A) and at B and C. Aortic expansion was defined as diameter increase of 5 mm or 15%. Correlation analyses were performed to investigate potential determinants of expansion.

Results

Median follow-up was 75.2 months. Sixteen of 18 patients (88.9%) demonstrated abdominal expansion. Mean expansion was 9.9 ± 6.1 mm at B and 11.7 ± 6.5 mm at C, without a difference between acute and chronic dissections. Critical diameters of 55 mm were reached in two patients treated for chronic dissection (11.1%). Annual diameter increase was significantly greater at locations with baseline diameters >30 mm (2.1 ± 1.1 mm vs. 1.0 ± 0.6 mm, p = 0.009). Baseline diameters were greater in patients with chronic dissections.

Conclusion

Abdominal aortic expansion can be frequently recognized after TEVAR for aortic dissection type B and occurs independently from thoracic false lumen thrombosis. Clinical significant abdominal aortic expansion may occur more frequently in patients treated with TEVAR for chronic dissection.

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.

Efficacy and Optimal Timing of Endovascular Treatment for Type B Aortic Dissection

OBJECTIVES

To determine the efficacy and the optimal timing of thoracic endovascular aortic repair (TEVAR) for closing the primary entry in uncomplicated patients with chronic type B aortic dissection and a patent false lumen (FL).

METHODS

Thirteen patients underwent TEVAR for aortic dissection between 2008 and 2012. These patients had chronic dissection with a patent FL and expansion of the aorta. Early TEVAR was performed for five patients within 1-7 months from the index dissection (TEVAR-EC group) and delayed TEVAR was performed for eight patients within 1-16 years (TEVAR-DC group). Changes in the diameters and volumes of the true lumen (TL) and FL and the aortic remodeling were assessed by multidetector computed tomography for 3 years after TEVAR.

RESULTS

The reduction rate of FL in the thoracic aorta was notably higher in the TEVAR-EC group than in the TEVAR-DC group regardless of the presence or absence of distal retrograde flow. There was a significant TL expansion despite different timings of TEVAR.

CONCLUSIONS

Early TEVAR resulted in good prognosis and preferable aortic remodeling in uncomplicated patients with chronic type B aortic dissection and a patent FL, and we recommend early TEVAR within seven months after the index dissection.

Biomechanical Changes After Thoracic Endovascular Aortic Repair in Type B Dissection

Thoracic endovascular aortic repair (TEVAR) has evolved into an established treatment option for type B aortic dissection (TBAD) since it was first introduced 2 decades ago. Morbidity and mortality have decreased due to the minimally invasive character of TEVAR, with adequate stabilization of the dissection, restoration of true lumen perfusion, and subsequent positive aortic remodeling. However, several studies have reported severe setbacks of this technique. Indeed, little is known about the biomechanical behavior of implanted thoracic stent-grafts and the impact on the vascular system. This study sought to systematically review the performance and behavior of implanted thoracic stent-grafts and related biomechanical aortic changes in TBAD patients in order to update current knowledge and future perspectives.

Current management of acute type B aortic dissection

Acute type B aortic dissection (TBAD) occurs as a result of an intimal tear within the proximal thoracic aorta. Patients are typically managed acutely with aggressive antihypertensive therapy. Surgical repair is reserved for those who develop complications such as rupture or malperfusion. The surgical management of acute TBAD has changed considerably in the last decade secondary to the advent of thoracic stent grafting. Thoracic endovascular aortic repair (TEVAR) has improved early mortality and morbidity rates for patients presenting with complicated TBAD. The role of TEVAR in patients presenting with acute and subacute uncomplicated TBAD is less clear. TEVAR has been associated with increased late survival and better aortic remodeling, with low perioperative morbidity in selected patients. Recent literature suggests certain radiographic criteria may be used to predict patients developing late aortic events who would benefit from early TEVAR. The purpose of this article is to review the contemporary management of acute TBAD, discuss controversies in management and evaluate the latest research findings.

Volumetric analysis of the initial index computed tomography scan can predict the natural history of acute uncomplicated type B dissections

OBJECTIVE

Our objective was to characterize the predictive impact of computed tomography (CT) scan volumetric analysis on the natural history of acute uncomplicated type B aortic dissections (ADs).

METHODS

We conducted a retrospective review of patients with acute type B ADs from 2009 to 2014. On an iNtuition workstation (TeraRecon, Foster City, Calif), volume measurements were obtained using the true lumen volume (TLV), false lumen volume (FLV), and total aortic volume from the left subclavian artery to the celiac artery. Growth rate was calculated as the change in maximal diameter between first and last available CT scans during the time interval. The primary outcome of the study was delayed aortic intervention. P < .05 was considered statistically significant.

RESULTS

During a 5-year period, 164 patients had CT scan evidence of acute type B ADs; 11 patients were excluded for lack of subsequent follow-up imaging; 36 patients who underwent urgent repair (<14 days from presentation) were also excluded. We evaluated a total of 117 patients: 85 patients who did not require intervention and 32 who underwent delayed (>14 days) thoracic endovascular aneurysm repair (29) or open repair (3). Mean age was 66 ± 12 years. Mean TLV/FLV ratio on initial CT scan was significantly higher in patients who did not eventually require an operation (1.55 vs 0.82; P = .02). The mean growth rate was higher in those eventually requiring operation (2.47 vs 0.42 mm/mo; P = .003). Patients were divided into three subgroups on the basis of their initial imaging TLV/FLV ratios (<0.8, 0.8-1.6, and >1.6). There was a significant difference in the growth rates between these three groups (4.6 vs 2.4 vs 0.8 mm/mo; P < .025). Area under the receiver operating characteristic curve analysis revealed that a TLV/FLV ratio <0.8 was highly predictive for requiring an intervention (area = 0.8; sensitivity, 69%; specificity, 84%: positive predictive value, 71%; negative predictive value, 81%), with an odds ratio of 12.2 (confidence interval, 5-26; P < .001). Conversely, a TLV/FLV ratio of >1.6 was highly predictive for freedom from delayed operation (sensitivity, 91%; specificity, 42%; positive predictive value, 61%; negative predictive value, 86%). After Kaplan-Meier analysis, 1-year and 2-year survival free of aortic interventions was 60% and 42% with a TLV/FLV ratio <0.8 and 92% and 82% with a ratio >1.6 (P = .001).

CONCLUSIONS

Initial CT scan volumetric analysis in patients presenting with uncomplicated acute type B ADs is a useful tool to predict growth and need for future intervention.

Open surgical repair for chronic type B aortic dissection: a systematic review

BACKGROUND

The treatment of chronic type B aortic dissection (CBAD) remains complicated. Thoracic endovascular aortic repair (TEVAR) has supplanted open surgical repair (OSR) as the preferred surgical treatment for CBAD. Despite TEVAR's superior short-term results, much less is understood about its long-term outcomes. As much of the understanding of OSR originates from historical report, contemporary series, with modern surgical techniques and technologies, may present an alternative to TEVAR. The present systematic review will assess the short- and long-term outcomes of historic and contemporary series of OSR for CBAD.

METHODS

Electronic searches were performed using six databases from their inception to March 2014. Relevant studies with OSRs for chronic type B dissection were identified. Data were extracted by two independent reviewers and analyzed according to predefined clinical endpoints. Studies were sub-classified into the pre-endovascular (historic series) and endovascular era (contemporary series) depending on whether the majority of cases were performed after 1999.

RESULTS

Nineteen studies were identified for inclusion for quantitative analysis. Pooled short-term mortality was 11.1% overall, and 7.5% in the nine contemporary studies. Stroke, spinal cord ischemia, renal dysfunction, and reoperation for bleeding were 5.9%, 4.9%, 8.1%, and 8.1%, respectively, for the contemporary series. Absolute late reintervention was identified in 13.3% of patients overall, and in 11.3% of patients in the contemporary series. Aggregated survival at 1-, 3-, 5-, and 10-years of all patients were 82.1%, 74.1%, 66.3%, and 50.8%, respectively.

CONCLUSIONS

OSR for chronic type B dissection in the contemporary era offers acceptable results. Management approaches should be considered carefully, taking into account both short-term and long-term complications. More research is required to clarify specific indications for OSR and TEVAR in chronic type B dissections.

Usefulness of new imaging methods for assessment of type B aortic dissection

While the medical management of uncomplicated type B aortic dissection has good outcomes in the short term, the longer term mortality can be in the region of 50% at 5 years. Up to 40% of the survivors can have significant dilatation of the false lumen with the risk of aneurysm formation and death due to rupture. The results of the randomized controlled trials ADSORB and INSTEAD-XL have shown that beneficial aortic remodelling occurs after endoluminal stent graft placement, but these trials were underpowered to show any effect on survival. Static computed tomography (CT) angiography imaging methods have been used to try to identify high risk patients using parameters such as diameter, the position and size of the entry tear, and the amount of false lumen thrombus, but these so far are not able to clinically risk stratify individual patients. In this manuscript, we present our initial experience with new MR imaging methods. These have allowed us to develop a greater understanding of aortic dissection by providing information regarding the underlying hemodynamic and biomechanics of the dissection, as well as more accurate assessment of important clinical imaging endpoints, such as false lumen thrombosis.

Mid-term outcomes and aortic remodelling after thoracic endovascular repair for acute, subacute, and chronic aortic dissection: the VIRTUE Registry

OBJECTIVE

The VIRTUE Registry describes the mid-term clinical and morphological results of thoracic endovascular repair (TEVR) in patients with type B aortic dissection.

METHODS

This was a prospective cohort study. The VIRTUE Registry is a prospective, multicentre clinical trial that enrolled patients with complicated acute (<15 days), subacute (15-92 days), and chronic (>92 days) type B aortic dissections treated with the Valiant endograft. One hundred patients were enrolled and the clinical outcomes described at the 3-year follow-up. Analysis of the aortic area and false lumen thrombosis rates defined the morphological response to TEVR in the three clinical groups.

RESULTS

Three-year all-cause mortality (18%, 4%, and 24%), dissection related mortality (12%, 4%, and 9%), aortic rupture (2%, 0%, and 4%), retrograde type A dissection (5%, 0%, and 0%), and aortic reintervention rates (20%, 22%, and 39%) were, respectively, defined for patients with acute (n = 50), subacute (n = 24), and chronic (n = 26) dissections. Analysis of aortic morphology observed that patients with subacute dissection demonstrated a similar degree of aortic remodelling to patients with acute dissection. Patients with acute and subacute dissection exhibited greater aortic plasticity than patients with chronic dissection.

CONCLUSIONS

The principle clinical findings suggest that TEVR is able to provide good protection from aortic-related death in the mid-term, but with a high rate of aortic reintervention. Analysis of aortic morphology suggested that aortic remodelling in subacute patients is similar to the acute group. Retention of aortic plasticity in the subacute group lengthens the therapeutic window for the treatment of uncomplicated type B dissection.

Stent graft therapy for false lumen aneurysmal degeneration in established type B aortic dissection (FADED) results in differential volumetric remodeling of the thoracic versus abdominal aortic segments

BACKGROUND

Despite optimal medical therapy of type B aortic dissections, false lumen aneurysmal degeneration of these established dissections (FADED) occur over long term (>6 months). The efficacy of thoracic stent grafts (thoracic endovascular aortic repair [TEVAR]) in promoting aortic remodeling when placed at late time points remains controversial and was the focus of this investigation.

METHODS

Utilizing tomographic scans, the volume of 6 distinct aortic compartments were calculated including the stented true lumen and stented false lumen (STL and SFL), below-stent true and false lumens (BSTL and BSFL), and the infrarenal aorta true and false lumens (IRA TL and IRA FL) when applicable. Cross-sectional areas were calculated at 1-cm intervals, collated, and volumetric ratios were derived from preoperative values.

RESULTS

From 2004 to 2011, 21 patients met inclusion criteria. Complete false lumen (FL) thrombosis was achieved in 85.7% of SFL and 26.3% of BSFL. Volumetric analysis demonstrated that 71% of patients had increased STL volume and 71% had decreased SFL. In the below-stent region, 75% of patients had increased true lumen (TL) with 59% concurrently decreased FL volume. The IRA TL volume increased in 85% of patients and the IRA FL also expanded in 75% of this cohort. At the latest time point, overall growth was noted in the infrarenal aortic segment.

CONCLUSIONS

Utilization of TEVAR in patients suffering from FADED can promote TL expansion with concurrent FL regression; however, progressive dilation in the total infrarenal aorta volume may occur and warrants close surveillance.

TEVAR for type B aortic dissection in Japan

TEVAR is a new strategy for treating both acute and chronic type B aortic dissection. The JSC guidelines classify TEVAR as a Class I recommendation for cases of complicated acute type B dissection and a Class IIa recommendation for cases of chronic type B aortic dissection. While TEVAR has been primarily applied to treat complicated acute type B aortic dissection in Europe and the USA, the procedure remains an off-label treatment strategy for aortic dissection in Japan. The current state of TEVAR for type B aortic dissection in Japan from 2001 to 2011 is estimated in the annual reports of the Japanese Association for Thoracic Surgery. The number of acute type B aortic dissection patients treated with transluminal stent grafting increased rapidly after 2008, from 10 cases in 2001 to 76 cases in 2010. Meanwhile, the number acute type B aortic dissection patients treated with any type of surgery has increased gradually, from 100 cases in 2001 to 194 cases in 2009. The number of chronic type B aortic dissection patients treated with transluminal stent grafting increased abruptly in 2010, reaching 346 cases, which accounted for one-third of all surgical procedures for chronic type B aortic dissection. Furthermore, the number of open surgeries for chronic type B aortic dissection has also increased gradually, from 401 cases in 2001 to 947 cases in 2011. At present, open surgery, TEVAR and hybrid procedures are available to treat patients with type B aortic dissection. The use of a multidisciplinary team approach is mandatory when selecting the appropriate surgical strategy.

Human ex-vivo model of Stanford type B aortic dissection

OBJECTIVE

To report a new human ex vivo model of type B aortic dissection (TBAD) and to assess if the locations of the primary entry tear determine the patterns of dissection propagation.

METHODS

Twenty fresh human aortas were harvested. TBADs were surgically initiated 2 cm below the left subclavian artery at four different locations (lateral, n = 5; medial, n = 5; anterior, n = 5; posterior, n = 5). Aortas were thereafter connected to a bench-top pulsatile flow model to induce antegrade propagation of the dissection.

RESULTS

Antegrade propagation of the dissection was achieved and reached at least the celiac trunk (CT) in all the cases. Dissection was propagated to the renal aorta in 16 (80%) and infrarenal aorta in seven cases (35%). Left renal artery with or without the CT originated more often from the false channel when primary entry tear was lateral. Right renal artery and the CT most often originated from the false channel when primary entry tear was medial. When the CT was the only one originating from the false channel, primary entry tear was more often anterior, whereas when it originated from the true channel, it was more often posterior.

CONCLUSIONS

This human ex vivo model of TBAD is reproducible, since, in all the aortas, extended dissection was achieved and provides the first model of human aortic dissection with infrarenal aorta extension allowing future assessment of endovascular devices developed for human use. Furthermore, it allows clarification of the patterns of aortic dissection propagation and visceral and renal artery involvement according to the site of the primary entry tear.

Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) represents a therapeutic concept for type B aortic dissection. Long-term outcomes and morphology after TEVAR for uncomplicated dissection are unknown.

METHODS AND RESULTS

A total of 140 patients with stable type B aortic dissection previously randomized to optimal medical treatment and TEVAR (n=72) versus optimal medical treatment alone (n=68) were analyzed retrospectively for aorta-specific, all-cause outcomes, and disease progression using landmark statistical analysis of years 2 to 5 after index procedure. Cox regression was used to compare outcomes between groups; all analyses are based on intention to treat. The risk of all-cause mortality (11.1% versus 19.3%; P=0.13), aorta-specific mortality (6.9% versus 19.3%; P=0.04), and progression (27.0% versus 46.1%; P=0.04) after 5 years was lower with TEVAR than with optimal medical treatment alone. Landmark analysis suggested a benefit of TEVAR for all end points between 2 and 5 years; for example, for all-cause mortality (0% versus 16.9%; P=0.0003), aorta-specific mortality (0% versus 16.9%; P=0.0005), and for progression (4.1% versus 28.1%; P=0.004); Landmarking at 1 year and 1 month revealed consistent findings. Both improved survival and less progression of disease at 5 years after elective TEVAR were associated with stent graft induced false lumen thrombosis in 90.6% of cases (P<0.0001).

CONCLUSIONS

In this study of survivors of type B aortic dissection, TEVAR in addition to optimal medical treatment is associated with improved 5-year aorta-specific survival and delayed disease progression. In stable type B dissection with suitable anatomy, preemptive TEVAR should be considered to improve late outcome.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01415804.

Efficacy of thoracic endovascular stent repair for chronic type B aortic dissection with aneurysmal degeneration

BACKGROUND

The Food and Drug Administration has approved devices for endovascular management of thoracic endovascular aortic aneurysm repair (TEVAR); however, limited data exist describing the outcomes of TEVAR for aneurysms attributable to chronic type B aortic dissection (cTBAD). This study was undertaken to determine the results of endovascular treatment of cTBAD with aneurysmal degeneration.

METHODS

A retrospective analysis of all patients treated for cTBAD with aneurysmal degeneration at the University of Florida from 2004 to 2011 was performed. Computed tomograms with centerline reconstruction were analyzed to determine change in aortic diameter, relative proportions of aortic treatment lengths, and false lumen perfusion status. Reintervention and mortality were estimated using life-tables. Cox regression analysis was completed to predict mortality.

RESULTS

Eighty patients underwent TEVAR for aneurysm due to cTBAD (mean age [± standard deviation], 60 ± 13 years [male, 87.5%; n = 70]; median follow-up, 26 [range, 1-74] months). Median time from diagnosis of TBAD to TEVAR was 16 (range, 1-72) months. Prior aortic root/arch replacement had been performed in 29% (n = 23) at a median interval of 28.5 (range, 0.5-312) months. Mean preoperative aneurysm diameter was 62.0 ± 9.9 mm. In 75% (n = 60) of cases, coverage was proximal to zone 3, and 24% (n = 19) underwent carotid-subclavian bypass or other arch debranching procedure. Spinal drains were used in 78% (pre-op 71%, n = 57; post-op 6%, n = 5). Length of stay was 6.5 ± 4.7 days with a composite morbidity of 26% and in-hospital mortality of 2.5% (n = 2). Overall neurologic event rate was 17% (spinal cord ischemia 10% [n = 8], with a permanent deficit observed in 6.2% [n = 5]; stroke 7.5%). Aneurysm diameter reduced or stabilized in 65%. The false lumen thrombosed completely within the thoracic aorta in 52%, and reintervention within the treated aortic segment was required in 16% (n = 13).One- and 3-year freedom from reintervention (with 95% confidence interval [CI]) was 80% (range, 68%-88%) and 70% (range, 57%-80%), respectively. Survival at 1 and 5 years was 89% (range, 80%-94%) and 70% (range, 55%-81%) and was not significantly different among patients requiring reintervention or experiencing favorable aortic remodeling. Multivariable analysis identified coronary artery disease (hazard ratio [HR], 6.4; 95% CI, 2.3-17.7; P < .005), prior infrarenal aortic surgery (HR, 8.6; 95% CI, 2.3-31.7; P = .001), and congestive heart failure (HR, 11.9; 95% CI, 1.9-73.8; P = .008) as independent risk factors for mortality. Hyperlipidemia was found to be protective (HR, 0.2; 95% CI, 0.05-0.6; P = .004). No significant difference in predictors of mortality were found between patients who underwent reintervention vs those who did not (P = .2).

CONCLUSIONS

TEVAR for cTBAD with aneurysmal degeneration can be performed safely but spinal cord ischemia rates may be higher than previously reported. Liberal use of procedural adjuncts to reduce this complication, such as spinal drainage, is recommended. Reintervention is common, but long-term survival does not appear to be impacted by remediation.