Endovascular Repair of Acute Type B Aortic Dissection: Long-Term Follow-Up of True and False Lumen Diameter Changes

Outcomes of symptomatic penetrating aortic ulcer and intramural hematoma in the endovascular era

BACKGROUND

Although endovascular technology has resulted in a paradigm shift in treatment, medical management remains the standard of care for penetrating aortic ulcer (PAU) and intramural hematoma (IMH). This study aimed to detail the short- and long-term outcomes of symptomatic PAU/IMH.

METHODS

Institutional data on symptomatic PAU/IMH were gathered (2005-2020). The primary outcome was the composite of recurrent symptoms, radiographic progression, intervention, rupture, and death from related or unknown cause. Factors associated with the primary outcome were determined using a Fine-Gray model with death from an unrelated cause as a competing risk.

RESULTS

A total of 83 symptomatic patients treated with medical management aside from ruptures and type A dissections: 21 isolated PAU, 30 isolated IMH, and 32 IMH and PAU. Adverse outcomes included symptom recurrence in 14 (16.9%), radiographic progression to dissection or saccular aneurysm in 17 (20.5%), surgery in 20 (24.1%) (17 thoracic endovascular aortic repair, 1 endovascular aortic repair, 1 frozen elephant trunk, and 1 open repair), and rupture in 4 (4.8%). Twenty-seven patients (32.5%) died during follow-up: 6 from IMH treatment complications, 8 from an unknown cause, and 13 from other causes. The 30-day, 1-year, and 5-year cumulative incidences of the primary outcome was 26.5% (95% confidence interval [CI], 16.9%-37.0%), 44.9% (95% CI, 32.8%-56.2%), and 57.5% (95% CI, 42.4%-69.9%), respectively. IMH with PAU was associated with a significantly higher risk of the primary outcome compared with isolated IMH (subdistribution hazard ratio, 2.21; 95% CI, 1.09-4.50; P = .027) and isolated PAU (subdistribution hazard ratio, 3.58; 95% CI, 1.44-8.88; P = .006).

CONCLUSIONS

Complications from symptomatic PAU and IMH are frequent, with intervention, recurrent symptoms, radiographic progression, rupture, or death affecting 25% of patients at 30 days after diagnosis and almost one-half of patients 1 year after diagnosis. Given the high rate of adverse events in this population, investigation into a more aggressive interventional strategy may warranted, especially in patients with a combined IMH and PAU.

MANAGEMENT OF LEFT SUBCLAVIAN ARTERY IN TYPE-B AORTIC DISSECTION TREATED WITH THORACIC ENDOVASCULAR AORTA REPAIR

OBJECTIVE

Thoracic endovascular aortic repair (TEVAR) has been the favored approach for the treatment of type B aortic dissection (TBAD). To obtain an adequate proximal landing zone, coverage of the left subclavian artery (LSA) will often be necessary. The occurrence of possible neurologic complications has continued to be debated. We investigated the management of the LSA in patients with TBAD undergoing endovascular repair.

METHODS

We searched the PubMed and MEDLINE databases to October 2020 for studies of TEVAR for TBAD. Data on the study design, demographics, endograft details, LSA coverage and revascularization, mortality, complications, and follow-up were extracted and analyzed. The effects of LSA coverage and revascularization on neurologic complications and outcomes were investigated.

RESULTS

A total of 26 reports (24 retrospective and 2 prospective) were deemed eligible for our study. A total of 1483 patients (mean age, 56.9 ± 6.2 years) had undergone TEVAR for acute (n = 932; 62.9%), subacute (n = 36; 2.4%), or chronic (n = 515; 34.7%) TBAD, with a success rate of 97.8% and hospital mortality of 4.9%. The LSA origin had been covered for 707 patients (47.7%), and 326 had undergone LSA revascularization (surgical, n = 96; endovascular, n = 170; unspecified or not reported, n = 60). LSA revascularization was concomitant for 68.1% of cases, after TEVAR for 1.8%, and not reported for 30.1%. Of 1146 patients, 10 (0.9%) had experienced left arm claudication, and the overall stroke rate was 3.3% (2.7% for the LSA group and 1% for the uncovered LSA group; P = .0815). Of the patients with stroke and a covered LSA, 1% (2 of 203) had undergone LSA revascularization and 4.8% (5 of 105) had not (P = .0478). Twenty-six patients (1.9%) had developed paraplegia: 0.7% (3 of 433) with a covered LSA, 1.4% (7 of 491) with an uncovered LSA (P = .3508), and not reported for 16 patients. Endoleak was present in 138 patients (13.4%) at a mean follow-up of 32.1 ± 25.6 months.

CONCLUSIONS

Our review has shown that LSA coverage during endovascular repair for complicated TBAD will does not significantly increase the risk of neurologic complications; however, revascularization of the LSA should be always recommended.

Methods and outcomes of endovascular false lumen embolization for thoracic aortic dissection

PURPOSE

To provide a contemporary review on endovascular false lumen (FL) embolization for thoracic aortic dissection (AD) and evaluate its early outcome.

METHODS

A systematic literature review on FL embolization for thoracic AD from January 2003 to December 2020 was performed under the instruction of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. Each article was analyzed using a standardized protocol including predefined demographic characteristics, perioperative mortality and major complications.

RESULTS

A total of 29 papers with 229 patients were included into the analysis. The methods of FL occlusion used were: the Candy-Plug technique, the knickerbocker technique, the "cork in the bottleneck" technique and direct FL embolization with combination of stent-grafts, coils, onyx, plugs and glue. FL embolization procedure was performed in 79 patients (34.5%) with type A AD and 150 (65.5%) with type B AD. FL direct embolization was the most frequently used technique, and it was applied in 198 (86.5%) patients. Candy-plug, knickerbocker and "cork in the bottleneck" techniques were used in 26 (11.4%), 3 (1.3%) and 2 (0.9%) patients, respectively. Technical success was achieved in all patients except one (228/229, 99.6%) in which implantation of a stent to celiac trunk was not possible. There were four hospital deaths (1.7%). Neurological complications occurred in 6 patients (2.6%), including 4 (1.7%) spinal cord ischemia and 2 (0.9%) ischemic stroke. There were 1 (0.4%) iatrogenic retrograde dissection and 2 (0.9%) renal failure reported. The mean duration of follow-up was 16.5 months. There were 21 deaths (9.3%) during follow-up, and 8 (3.6%) were aorta-related. Thirty-three (14.7%) secondary intervention were performed. Five patients (2.2%) required open completion thoracoabdominal procedure incorporating the stent-graft into the repair. Complete FL thrombosis was observed in 181 (80.4%) patients, 34 (15.1%) had partial thrombosis, and 10 (4.4%) had FL progression.

CONCLUSIONS

FL embolization of the distal thoracic aorta is a promising technique in a group of patients to promote FL thrombosis and aortic remodeling in thoracic aorta.

Endovascular repair of acute complicated type B aortic dissection-systematic review and meta-analysis of long-term survival and reintervention

Background

Thoracic endovascular repair (TEVAR) is considered the first-line therapy in the repair of acute complicated type B aortic dissection (AC-BAD). Given the difficulty of designing randomized trials in this surgical cohort, long-term outcome data is limited. This systematic review and meta-analysis provide a complete aggregation of reported long-term survival and freedom from reintervention of AC-BAD patients based on the existing literature.

Methods

Three databases were searched from date of database inception to January 2021. The relevant references were identified and baseline cohort characteristics, survival and freedom from reintervention were extracted. The primary endpoints were survival and freedom from reintervention, whilst secondary endpoints were post-operative outcomes such as cord ischemia and endoleak. Kaplan-Meier curves were digitized and aggregated as per established procedure.

Results

A total of 2,812 references were identified in the literature search for review, with 46 selected for inclusion. A total of 2,565 patients were identified, of which 1,920 (75%) were male. The mean age of the cohort was 59.8±5.8. Actuarial survival at 2, 4, 6 and 10 years was 87.5%, 83.2%, 78.5% and 69.7%, respectively. Freedom from all secondary reintervention at 2, 4, 6, 8 and 10 years was 74.7%, 69.1%, 65.7%, 63.9% and 60.9%, respectively. When accounting for study quality, actuarial survival at 2, 4, 6 and 8 years was 85.4%, 79.1%, 69.8% and 63.1%, respectively. Freedom from all secondary reintervention at 2, 4, 6 and 8 years was 73.2%, 67.6%, 63.7% (maintained), respectively.

Conclusions

TEVAR is associated with promising long-term survival extended to 10 years, though rates of freedom from reintervention remain an ongoing point for improvement. Randomized controlled trials comparing endovascular with open repair in the setting of acute, complicated type B aortic dissection are needed.

Endovascular Stent-Graft Repair of the Ascending Aorta: Assessment of a Specific Novel Stent-Graft Design in Phantom, Cadaveric, and Clinical Application

Purpose

To test a stent-graft specifically designed for the ascending aorta in phantom, cadaver, and clinical application, and to measure deployment accuracy to overcome limitations of existing devices.

Methods

A stent-graft has been designed with support wires to fixate the apices toward the inner curvature, thereby eliminating the forward movement of the proximal end which can happen with circumferential tip capture systems. The device was deployed in three aortic phantoms, and in four cadavers, deployment precision was measured. Subsequently, the device was implanted in a patient to exclude a pseudoaneurysm originating from the distal anastomosis after ascending aortic replacement.

Results

The stent-grafts were successfully deployed in all phantoms and cadavers. Deployment accuracy of the proximal end of the stent-graft was within 1 mm proximally and 14 mm distally to the intended landing zone on the inner curvature, and 2–8 mm distal to the intended landing zone on the outer curvature. In clinical application, the pseudoaneurysm could be successfully excluded without complications.

Conclusion

The novel stent-graft design promises accurate placement in the ascending aorta. The differential deployment of the apices at the inner and outer curvatures allows deployment perpendicular to the aortic axis.

Level of Evidence

No level of evidence.

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.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

Full PETTICOAT in acute type B aortic dissection with patent false lumen may offer positive remodeling for the distal aorta

OBJECTIVE

The provisional extension to induce complete attachment (PETTICOAT) technique is a unique thoracic endovascular aortic repair (TEVAR) for aortic dissection, which consists of proximal descending aortic endografting plus distal bare-metal stenting. This study aimed to investigate the efficacy of the PETTICOAT technique in patients with acute-sub-acute complicated type B aortic dissections. In particular, we compared the remodeling effect of full PETTICOAT covering down to the abdominal aorta with that of simple entry closure.

METHODS

In this retrospective pre-post study, we compared the clinical course of consecutive patients undergoing TEVAR with the PETTICOAT technique in which proximal entry tear was excluded with a covered stent, and extension bare stents were placed down to the abdominal segment for acute-sub-acute complicated type B aortic dissections, between 2015 and 2017, with a control group treated with TEVAR with entry closure between 2011 and 2015. Outcomes included the aortic remodeling rate and the aortic diameter up to 1 year after surgery.

RESULTS

Subjects consisted of 47 patients (21 in full PETTICOAT group, 26 in the simple entry closure group). The remodeling rate of the abdominal aorta in the full PETTICOAT group was significantly higher than in the simple entry closure group (p < 0.05), while that of the thoracic aorta was comparable between the two groups.

CONCLUSIONS

This study suggests that the full PETTICOAT technique achieves better aortic remodeling compared to entry closure alone, and might lead to less reintervention.

Modified frozen elephant trunk procedure as standard approach in acute type A aortic dissection: A propensity-weighted analysis

OBJECTIVES

To evaluate whether the modified frozen elephant trunk (mFET) procedure provides comparable outcome compared with the standard approach for DeBakey type I aortic dissection.

METHODS

From November 2008 to December 2018, 262 (mean age 62.7 ± 12.4 years) patients with acute DeBakey type I aortic dissection were included. mFET was performed in 100 (38.2%) patients and isolated ascending aorta and hemiarch replacement (iAoA) were performed in 162 (61.8%). Outcome analyses included in-hospital mortality, stroke rate, incidence of composite cardiovascular events, survival, freedom from aorta-related intervention, as well as freedom from neurologic event. Inverse probability of treatment weighting was applied.

RESULTS

After inverse probability of treatment weighting, in-hospital mortality was greater in the iAoA group. The incidence of cardiac cause of death, new postoperative renal failure, as well as stroke rate were similar in both groups. The survival at 1 year, 3 years, and 4 years was 84%, 81%, and 77%, respectively, in the iAoA group and 91%, 86%, and 86%, P = .025, respectively, in the mFET group. Cause-specific HR for aortic reoperation 1.03 (confidence interval [CI], 0.43-2.48, P = .95) and neurovascular event 2.72 (CI, 0.62-11.93, P = .19) was similar in 2 groups. Subhazard ratio (sHR) for mortality as competing outcome for aorta-related reintervention sHR of 0.52 (CI, 0.32-0.86, P = .011) and neurologic event sHR of 0.45 (95% CI, 0.26-0.76, P = .003) was significantly lower in mFET.

CONCLUSIONS

The mFET procedure as surgical treatment modality for DeBakey type I acute aortic dissection may be considered as viable alternative with beneficial mid-term outcome.

Geometric Analysis of Type B Aortic Dissections Shows Aortic Remodeling After Intervention Using Multilayer Stents

Recently, multilayer stents for type B aortic dissections (TBAD) have been proposed to decrease false lumen flow, increase and streamline true lumen flow, and retain branch vessel patency. We aimed to provide a protocol with standardized techniques to investigate aortic remodeling of TBAD by multilayer flow modulators (MFM) in static geometric and hemodynamic analyses. Combining existing literature and new insights, a standardized protocol was designed. Using pre- and postoperative CT scans, geometric models were constructed, lumen dimensions were calculated, computational fluid dynamics (CFD) models were composed, and velocity and pressures were calculated. Sixteen TBAD cases treated with MFM were included for analysis. For each case, aortic remodeling was analyzed using post-processing medical imaging software. After 3D models were created, geometrical anatomical measurements were performed, and meshes for finite element analysis were generated. MFM cases were compared pre- and postoperatively; true lumen volumes increased (p < 0.001), false lumen volumes decreased (p = 0.001), true lumen diameter at the plane of maximum compression (PMC) increased (p < 0.001), and false lumen index decreased (p = 0.008). True lumen flow was streamlined, and the overall fluid velocity and pressures decreased (p < 0.001 and p = 0.006, respectively). This protocol provided a standardized method to evaluate the effects of MFM treatments in TBAD on geometric analyses, PMC, and CFD outcomes.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Assessing Aortic Remodeling after Thoracic Endovascular Aortic Repair (TEVAR) in DeBakey IIIb Aortic Dissection: A Retrospective Study

PURPOSE

This study analyzed the different levels of aortic remodeling in patients with DeBakey IIIb aortic dissection (AD) after thoracic endovascular aortic repair (TEVAR) at a single center.

METHODS

In all, 66 patients with DeBakey IIIb AD who underwent TEVAR in the acute (Group A) or subacute phase (Group SA) from January 2012 to October 2016 were included in the study. The change in aortic lumen (A), true lumen (TL), false lumen (FL), and true lumen index (TLi) at different levels were analyzed.

RESULTS

There was no statistically significant difference in the clinical information and morphologic imaging findings in Groups A and SA. At proximal levels (levels A-C), there was no difference in aortic remodeling parameters, that is, increased TL, decreased FL, and increased TLi at levels B and C and stable A at levels A-C, in both groups. Moreover, the above parameters were illustrated using a box-and-whisker plot, which revealed the unstable acute phase by the larger distribution interval and the median and abnormal values of the right skew distribution in Group A.

CONCLUSION

Postoperative surveillance is important for patients of both acute and subacute AD.

Aortic Remodeling After Total Endovascular Aortic Repair With Multilayer Stents: Computational Fluid Dynamics Analysis of Aortic Remodeling Over 3 Years of Follow-up

PURPOSE

To report Multilayer Flow Modulator (MFM) implantation from the sinotubular junction to the distal infrarenal aorta in the treatment of type B aortic dissection (TBAD) and demonstrate aortic remodeling using computational fluid dynamics (CFD) analysis over the course of 3-year follow-up.

CASE REPORT

A hypertensive patient with complicated TBAD required thoracic endovascular aortic repair due to severe thoracic pain associated with rapid progression of the false lumen aneurysm toward the distal aortic arch. Under general anesthesia, 2 aortic multilayer stents were placed over a 0.035-inch stiff guidewire in the compressed true lumen. The aorta was covered with 2 MFM stents between the sinotubular junction and the distal infrarenal aorta. Serial computed tomography scans showed progressive remodeling of the entire dissected aortic wall, with an excellent result at 24 months. Morphological and CFD vascular analysis confirmed the aortic remodeling, with a false lumen index drop from a preoperative 4.04 to 0.01 at 36 months.

CONCLUSION

Endovascular aortic repair with multilayer stents is a promising treatment for complicated TBAD due to the unique ability of these devices to stabilize the entire aortic wall without compromising the flow in the major aortic side branches.

Acute type A aortic dissection: Rationale and outcomes of extensive repair of the arch and distal aorta

Type A acute aortic dissection represents one of the most complex and life-threatening disorders of the cardiovascular system. Cardiac tamponade caused by ascending aorta rupture is the most common cause of death. In light of this, emergent surgery with ascending and partial arch replacement represents, in most of cases, the best and the faster therapeutic option. The natural history of aortic dissection, however, teaches us that in most cases there is a distal progression of the aortic disease that often requires further surgical and/or endovascular treatments. In light of this, it can be hypothesized that, by increasing the extent of aortic replacement during the first operation, it may improve the outcome of these patients by reducing the probability of a second surgery or, in selected cases and for appropriate indications, by treating with a single surgical step, the disease. In this short review of the literature, we focalized on the rationale and outcome of an extensive repair of the thoracic aorta.

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.

Outcomes of Thoracic Endovascular Aortic Repair for Acute Type B Dissection in Patients With Intractable Pain or Refractory Hypertension

PURPOSE

To compare uncomplicated acute type B aortic dissection (UATBAD) patients with intractable pain/refractory hypertension treated with thoracic endovascular aortic repair (TEVAR) to UATBAD subjects without these features receiving best medical therapy (BMT).

METHODS

Interrogation of the hospital database identified 101 consecutive UATBAD patients admitted between January 2011 and December 2014. Of these, 74 patients (mean age 62±13 years; 44 men) were treated with BMT; the other 27 UATBAD patients (mean age 63±13 years; 17 men) were subsequently treated with TEVAR for intractable pain (24, 89%) and/or refractory hypertension (3, 11%) at a mean 2.4±3.3 days (median 1, range 0-12) after admission. Mixed models were employed to determine differences in centerline measured aortic remodeling. Propensity analysis was employed to mitigate selection bias. Kaplan-Meier methodology was used to estimate reintervention and survival.

RESULTS

The groups were well matched; there was no difference in demographics, comorbidities, or proportion with visceral involvement (70% for TEVAR vs 86% for BMT, p=0.08). There was no significant difference in length of stay (9.6±6.3 for TEVAR vs 10.3±7.8 for BMT, p=0.3), complications (19% for TEVAR vs 24% for BMT, p=0.6), or 30-day mortality (0 for TEVAR vs 7% for BMT, p=0.1). One (4%) TEVAR patient experienced retrograde dissection. BMT resulted in greater mean increase in discharge antihypertensive medications (1.7±1.9 vs 0.7±1.7 for TEVAR, p=0.03), but there was no difference in narcotic utilization. Mean follow-up was greater in the TEVAR group (17.9±16.0 months) compared with BMT patients (11.5±10.8 months, p=0.05). TEVAR significantly improved rates of aortic diameter change (1.5% vs 12.9% for BMT, p=0.007), complete false lumen thrombosis (41% vs 11% for BMT, p=0.004), and true lumen expansion (85% vs 7% for BMT, p<0.01). However, there was no difference in reintervention (25.9% for TEVAR vs 23% for BMT, p=0.2) or survival (log-rank p=0.8).

CONCLUSION

TEVAR for UATBAD with intractable pain/refractory hypertension is safe but offers no short-term outcome advantage when compared to UATBAD patients without these features receiving BMT. A significant improvement in aortic remodeling was identified after TEVAR. The potential long-term reintervention and aorta-related mortality benefits of this favorable remodeling have yet to be defined and randomized trials are warranted.

Recent evolution in use and effectiveness in mainland China of thoracic endovascular aortic repair of type B aortic dissection

A meta-analysis was performed on 175 studies selected among those published in mainland China between 2008 and 2015 on thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (AD). Most TEVAR were performed in Shanghai, Beijing, Hubei and Guangdong in patients with mean age of 53.9 years, and acute (70%) or chronic (30%) type B AD. Procedural success rate was 99.1 ± 0.8%. Major complication rate was 1.7 ± 2.3%, with paraplegia in 0.4 ± 0.0%. Overall in-hospital mortality rate was 1.6 ± 0.9% with AD rupture in 30% (about 40% during first postoperative day); follow-up mortality rate was 2.3 ± 1.1%, with AD rupture in 39.2% (50% within first year). Compared with 2001–2007 data from China, there appeared to be improvement in rates of major complications, paraplegia and in-hospital mortality. Compared with 1999–2004 Western data, rates of procedural success, stroke, and paraplegia appeared similar, while those for major complications, in-hospital mortality, retrograde type A dissection and follow-up mortality appeared lower. Compared with more recent Western data (2006–2013) on acute complicated type B AD, stroke, paraplegia, in-hospital mortality and follow-up mortality appeared lower. Therefore, in mainland China, safety for TEVAR of type B AD appeared better between 2008 and 2015 than in previous periods in China or Western countries.

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.

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.

The new indication of TEVAR for uncomplicated type B aortic dissection

The classical therapeutic indication for type B aortic dissection is based on either medication or open surgery; medication therapy is recommended for relatively stable uncomplicated type B aortic dissection. With improvements in endovascular repair and the potential risk of disease progression, it is now necessary to evaluate the requirement for revision of the therapeutic choice of uncomplicated type B aortic dissection based on morphological features and time window. Data from 252 patients diagnosed as uncomplicated type B aortic dissection from 1992 to 2015 were analyzed retrospectively. Among these cases, 117 patients received medication therapy and 135 patients underwent endovascular repair. The 60-month survival rate in the endovascular group was higher than that in the medication group (92.3% vs 67.6%). According to the morphological evaluation, visceral artery involvement and false/true lumen ratios over 0.7 were strong risk factors for medical treatment alone. Increased surgical time and blood loss were found in patients treated in the chronic phase, compared with those who underwent endovascular repair within 14 days of the onset of symptoms. With improvements in aortic remodeling techniques, endovascular repair has been shown to improve long-term survival rates of patients with uncomplicated aortic dissection. Considering the potential risk of death, we recommend that patients with visceral artery involvement and a false/true lumen ratio over 0.7 should receive endovascular repair aggressively. Furthermore, delayed endovascular repair in the chronic phase does not improve the long-term outcome of uncomplicated type B aortic 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.

Endovascular repair of Stanford B aortic dissection using two stent grafts with different sizes

OBJECTIVE

The objective of this study was to introduce a novel strategy for thoracic endovascular aortic repair of Stanford B aortic dissection using two-stent graft implantation (TSI), in which the proximal stent and distal stent with different sizes are sequentially deployed, and to summarize our experience with this technique.

METHODS

A retrospective study was conducted of 72 consecutive patients (61 men; mean age, 55 ± 7 years; range, 41-67 years) with Stanford type B aortic dissection who underwent TSI treatment between January 2012 and May 2013. Among all patients, 43 (59.7%) involved the infrarenal aorta and 29 (40.3%) involved the whole thoracic and abdominal aorta; mean aortic involvement length was 226 ± 13 mm (range, 182-312 mm). Eight cases were for acute dissection (within 2 weeks from onset of symptoms), 11 cases were for chronic dissection (>3 months after initial dissection), and 53 cases were for subacute dissection (between 2 weeks and 3 months). Twenty-two cases (30.6%) were uncomplicated type and 50 cases (69.4%) were complicated type. Follow-up was performed postoperatively at 1 month, 6 months, and yearly thereafter. Technique success, aorta morphology, and procedure-related complications were evaluated.

RESULTS

Technical success was achieved in 100%; 72 pairs of stent grafts (144 thoracic stent grafts) and 10 left subclavian artery chimney stents were used. The mean aortic length coverage by the stent grafts was 197.6 ± 20.3 mm, and mean taper diameter span was 7.5 ± 1.8 mm. All patients were followed up from 6 to 16 months (mean, 10 ± 4 months); 95.8% (69 of 72) had a thrombosed false lumen in the aortic coverage, and the true lumen expanded on average 57% ± 11% (23%-100%). No significant changes were found in aortic diameters of the proximal and distal ends of the two stent grafts and the angles between centerlines of the distal end of the stent and the aorta during follow-up. Procedure-related complications included transient paraplegia (coverage of the left subclavian artery without revascularization and extensive coverage of aorta >220 mm) due to acute spinal cord ischemia (n = 1) and malapposition of the distal stent (primary tear closed, true lumen expansion led to oversize rate insufficient in distal stent diameter; n = 1). No death or malperfusion complications were observed during the perioperative period and follow-up.

CONCLUSIONS

Short-term outcomes showed TSI to be a flexible and effective approach to accurately repair Stanford B aortic dissection that could potentially address the limitations of currently available stent grafts. Further prospective clinical studies are warranted to evaluate its long-term efficacy.

Type B Aortic Dissection: A Review of Prognostic Factors and Meta-analysis of Treatment Options

According to international guidelines, stable patients with uncomplicated Type B aortic dissection (TBAD) should receive optimal medical treatment. Despite adequate antihypertensive therapy, the long-term prognosis of these patients is characterized by a significant aortic aneurysm formation in 25-30% within four years, and survival rates from 50 to 80% at five years and 30 to 60% at 10 years. In a prospective randomized trial, preemptive thoracic endovascular aortic repair (TEVAR) in patients with chronic uncomplicated TBAD was associated with an excess early mortality (due to periprocedural hazards), but the procedure showed its benefit in prevention of aortic-specific mortality at five years of follow-up. However, preemptive TEVAR may not be the treatment of choice in all patients with uncomplicated TBAD because of the inherent periprocedural complications like stroke, paraparesis, and death, as well as stent graft-induced complications (i.e., retrograde dissection or endoleaks). Thus, the TEVAR-related deaths and complications (especially paraplegia and stroke) raise concerns that moderate the better survival with TEVAR at five years. By timely identification of those patients prone for developing complications, early intervention, preferably in the subacute or early chronic phase, may improve the overall long-term outcome for these patients. Therefore, early detectable and reliable prognostic factors for adverse events are essential to stratify patients who can be treated medically and those who will benefit from rigorous follow-up and, in the long-term, from timely, or even prophylactic, TEVAR. Several studies have identified prognostic factors in TBAD such as aortic diameter, partial false lumen thrombosis, false lumen thickness, and location of the primary entry tear. Combining these clinical and radiological predictors may be essential to implement a patient-specific approach designed to intervene only in those patients who are at high risk of developing complications to improve the long-term outcomes of patients with uncomplicated Type B aortic dissection.

Indication of endovascular treatment of type B aortic dissection--literature review

Aortic dissection is a cardiovascular event of high mortality if not early diagnosed and properly treated. In Stanford type A aortic dissection, there is the involvement of the ascending aorta, whereas in type B the ascending aorta is not affected. The treatment of type A aortic dissection is mainly surgical. The hospital mortality of type B aortic dissection surgical treatment is approximately 20%, while medical therapy is 10%. However, half the patients who are discharged from hospital after medical treatment, progress to aortic complications in the following years, and the mortality in three to five years may reach 25-50%. In addition, the surgical treatment of aortic complications after medical treatment, has also a significant mortality. This way, the endovascular treatment comes up as an interesting alternative of a less invasive treatment for this disease. They presented a mortality rate lower than 10% with more than 80% success rate of occlusion and thrombosis of the false lumen. The INSTEAD TRIAL, which randomized patients with uncomplicated type B aortic dissection for optimal medical therapy and endovascular treatment in addition to optimal medical therapy, showed that after three years of follow up, patients who underwent endovascular treatment had lower mortality and aorta-related complications. Therefore, there is a current tendency to recommend the endovascular treatment as a standard for the treatment of type B aortic dissection

Pathology-specific secondary aortic interventions after thoracic endovascular aortic repair

OBJECTIVE

Despite improved short-term outcomes, concerns remain regarding durability of thoracic endovascular aortic repair (TEVAR). The purpose of this analysis was to evaluate the pathology-specific incidence of secondary aortic interventions (SAI) after TEVAR and their impact on survival.

METHODS

Retrospective review was performed of all TEVAR procedures and SAI at one institution from 2004-2011. Kaplan-Meier analysis was used to estimate survival.

RESULTS

Of 585 patients, 72 (12%) required SAI at a median of 5.6 months (interquartile range, 1.4-14.2) with 22 (3.7%) requiring multiple SAI. SAI incidence differed significantly by pathology (P = .002) [acute dissection (21.3%), postsurgical (20.0%), chronic dissection (16.7%), degenerative aneurysm (10.8%), traumatic transection (8.1%), penetrating ulcer (1.5%), and other etiologies (14.8%)]. Most common indications after dissection were persistent false lumen flow and proximal/distal extension of disease. For degenerative aneurysms, SAI was performed primarily to treat type I/III endoleaks. SAI patients had a greater mean number of comorbidities (P < .0005), stents placed (P = .0002), and postoperative complications after the index TEVAR (P < .0005) compared with those without SAI. Freedom from SAI at 1 and 5 years (95% confidence interval) was estimated to be 86% (82%-90%) and 68% (57%-76%), respectively. There were no differences in survival (95% confidence interval) between patients requiring SAI and those who did not [SAI 1-year, 88% (77%-93%); 5-year, 51% (37%-63%); and no SAI 1-year, 82% (79%-85%); 5-year, 67% (62%-71%) (log-rank, P = .2)].

CONCLUSIONS

SAI after TEVAR is not uncommon, particularly in patients with dissection, but does not affect long-term survival. Aortic pathology is the most important variable impacting survival and dictated need, timing, and mode of SAI. The varying incidence of SAI by indication underscores the need for diligent surveillance protocols that should be pathology-specific.

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.

A systematic review of aortic remodeling after endovascular repair of type B aortic dissection: methods and outcomes

BACKGROUND

Endovascular treatments of Stanford type B aortic dissection may help to promote aortic remodeling and reduce the incidence of aortic-related complications. The aim of this study was to review published literature describing aortic remodeling after endovascular treatment of aortic dissection.

METHODS

A systematic review of the literature was performed which was compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The type of aortic morphology measurements made and the methods used to make them were characterized. The endpoints of interest were the change in these measurements over time.

RESULTS

After initial screening, 77 articles were identified; 16 of which met the inclusion criteria. Few studies used three-dimensional reconstruction software and none had validated their measurement protocol. True lumen (TL) and false lumen (FL) diameters, areas, and in some cases volumes were measured. Studies assessed the aorta at a variety of different levels and over different periods of follow-up. Acute dissection patients displayed more consistent degree of remodeling (thoracic FL thrombosis in 80% to 90%) than chronic dissection patients (38% to 91%). Less remodeling was seen below the diaphragm in both groups.

CONCLUSIONS

Aortic remodeling after treatment for dissection is described in a highly heterogeneous manner. Despite this there appears to be a greater degree of complete FL resolution in patients with acute dissection than chronic. Factors such as length of aortic coverage and timing of treatment may explain the variation seen in the chronic dissection group. Consensus-based reporting standards are required to synthesize evidence and inform clinical decisions regarding patient selection and operative timing.

Predictors of late aortic events after Stanford type B acute aortic dissection

OBJECTIVE

Patients with Stanford type B acute aortic dissection usually receive medical treatment during the acute phase. The present study aimed to elucidate the factors predicting late aortic events in patients treated conservatively for acute type B dissections.

METHODS

From March 1991 to March 2011, 117 patients were enrolled in the present study, with a mean follow-up period of 5.1 ± 4.1 years. The patients were divided into 4 groups according to their false lumen status at onset: group F, fully open (n = 26, 22.2%); group P, partially thrombosed (n = 23, 19.6%); group U, ulcer-like projections (n = 22, 18.9%); and group T, completely thrombosed (n = 46, 39.3%).

RESULTS

Long-term survival did not significantly differ among the groups. The Kaplan-Meier event-free rate curve showed that aortic events occurred less frequently in group T than in the other 3 groups; the 5-year event-free rate was 65.4%, 58.8%, 36.1%, and 95.7% for groups F, P, U, and T, respectively. Cox regression analysis showed that the presence of ulcer-like projections (P = .016) and a maximum aortic diameter of ≥ 40 mm (P = .003) were predictors of late aortic events.

CONCLUSIONS

When patients have a maximum aortic diameter of ≥40 mm or ulcer-like projections at onset, early surgical intervention should be considered to prevent positive remodeling of the aorta.

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.

Hybrid approach in an acute type B aortic dissection in a female patient after having a renal transplant

This study describes our experiences with a 44-year-old woman who developed acute type B aortic dissection and elected emergency surgery 3 years after a renal transplant. This led to acute ischemia in the right lower extremity. The first stage of surgery was to implant an extra-anatomic (pretracheal) bypass with a GORE-TEX prosthesis from the brachiocephalic trunk to the left common carotid artery. The second stage was implanting a stent graft into the aortic arch that covered the left common carotid artery and the left subclavian artery. The third stage was to insert a stent graft that involved the entire thoracic aorta and proximal segment of the abdominal aorta to the celiac trunk, with the right axillary and left femoral approach. The fourth stage was an extra-anatomic (suprapubic) bypass with the GORE-TEX prosthesis from the left femoral artery to the right femoral artery. Surgery resulted in normal blood supply to the organs and restored renal function.