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

Is TEVAR an Effective Approach to Prevent Complications after Surgery for Aortic Dissection Type A? A Systematic Review

Introduction: A residual false lumen after treatment for Aortic Dissection type A (AD) has been associated with early complications, such as A malperfusion or rupture and mid-term or delayed complications, such as aneurysm formation or dissection expansion. Thoracic Endovascular Aortic Repair (TEVAR) is considered an effective solution by several surgical teams to prevent future complications. In this systematic review, all published data regarding the implementation of TEVAR after previous treatment for AD were collected in order to investigate indications, methods, clinical outcomes and aortic remodeling in these patients. Methods: The aim of this study was to investigate the indications, the methods and the efficacy of TEVAR usage after surgical treatment of AD. Data for this study were collected from four widely used medical databases (MEDLINE, SCIENCE DIRECT, GOOGLE SCHOLAR, OVID). All the results for each database were recorded and were analyzed with a systematic method. Techniques and clinical outcomes were investigated. Aortic remodeling was evaluated based on the following parameters in these studies: aortic diameter, true lumen diameter, false lumen diameter, false lumen thrombosis and false lumen patency. Results: The results obtained from the search among all databases comprised 1410 articles and of these articles 9 were included in the review. The majority of the studies were retrospective (seven out of nine studies), while no study was randomized. The total number of patients was 157 and 133 of them (84.7% of patients) were treated with TEVAR in zone 3 without extension below the diaphragm intraoperatively. Among 142 patients, the calculated mortality rate was 12.7% (18 of 142 patients), with 2.8% (4 of 142 patients) presenting with stroke. The percentage of patients with total or partial thrombosis combined was 65.9% (62 patients in a population of 92). The reintervention rate was 18.7%. Conclusions: TEVAR after AD surgery is an approach usually chosen in clinical practice, but the criteria of its usage are uncertain. This method is safe and enhances aortic remodeling with an acceptable reintervention rate. Definite guidelines in this field should be created in order to delineate whether TEVAR after AD surgery is beneficial as a preventive measure to aorta-related complications and to decide under which criteria this approach should be chosen.

Volume Changes in the Descending Aorta after Frozen Elephant Trunk and Conventional Hemi-Arch Repair after Acute Type A Aortic Dissection

The aim of this study was to compare the mortality rates, re-intervention rates, and volumetric changes in aortas following surgery, in terms of the true lumen and false lumen changes, using conventional hemi-arch repair (CET) and frozen elephant trunk (FET) techniques. During the period from 2015 to 2018, 66 patients underwent surgical treatment for acute aortic dissection (Debakey type 1). Demographic and procedure-related data were evaluated. We measured volumetric change before surgical treatment, at discharge, and at 12- and 24-month time points based on computed tomography angiography. The study cohort was divided into two groups (FET vs. CET). The mean age of the patients was 56.9 ± 9.4 years in the FET group versus 63.6 ± 11 years in the CET group (p = 0.063). The mean follow-up time was 24 ± 6 and 25 ± 5 months for the FET and CET groups, respectively. There were no significant differences between the two groups in terms of the medical histories of the cohorts. The results showed a significant increase in true lumen volume after the FET procedure (within 24 months postoperatively; p = 0.005), and no significant changes in total (p = 0.392) or false lumen (p = 0.659) volumes were noted. After the CET procedure, there were significant increases in total and false lumen volumes (p = 0.013, p = 0.042), while no significant change in true lumen was observed (p = 0.219). The volume increase in true lumen after the FET procedure was higher compared to the CET group at all postoperative time points (at discharge, 12 months, and 24 months) without significant evidence (p = 0.416, p = 0.422, p = 0.268). At two years, the volume increase in false lumen was significantly higher among the CET group compared to the FET group (p = 0.02). The Kaplan–Meier curve analysis showed that patients who underwent the CET procedure underwent significantly more re-interventions due to false lumen expansion of the descending aorta (p = 0.047). Present study results indicate that the true and false lumen changes in the aorta following the FET and CET procedures were different. FET led to a significant increase in true lumen volume, while false lumen volume remained stable; however, after the CET procedure, significant false lumen enlargement was noted at mid-term follow-up time points. The re-intervention rate after CET was higher due to false lumen expansion.

Baseline 4D Flow-Derived in vivo Hemodynamic Parameters Stratify Descending Aortic Dissection Patients With Enlarging Aortas

Purpose

The purpose of our study was to assess the value of true lumen and false lumen hemodynamics compared to aortic morphological measurements for predicting adverse-aorta related outcomes (AARO) and aortic growth in patients with type B aortic dissection (TBAD).

Materials and Methods

Using an IRB approved protocol, we retrospectively identified patients with descending aorta (DAo) dissection at a large tertiary center. Inclusion criteria includes known TBAD with ≥ 6 months of clinical follow-up after initial presentation for TBAD or after ascending aorta intervention for patients with repaired type A dissection with residual type B aortic dissection (rTAAD). Patients with prior descending aorta intervention were excluded. The FL and TL of each patient were manually segmented from 4D flow MRI data, and 3D parametric maps of aortic hemodynamics were generated. Groups were divided based on (1) presence vs. absence of AARO and (2) growth rate ≥ vs. < 3 mm/year. True and false lumen kinetic energy (KE), stasis, peak velocity (PV), reverse/forward flow (RF/FF), FL to TL KE ratio, as well as index aortic diameter were compared between groups using the Mann–Whitney U or independent t-test.

Results

A total of n = 51 patients (age: 58.4 ± 15.0 years, M/F: 31/20) were included for analysis of AARO. This group contained n = 26 patients with TBAD and n = 25 patients with rTAAD. In the overall cohort, AARO patients had larger baseline diameters, lower FL-RF, FL stasis, TL-KE, TL-FF and TL-PV. Among patients with de novo TBAD, those with AAROs had larger baseline diameter, lower FL stasis and TL-PV. In both the overall cohort and in the subgroup of de novo TBAD, subjects with aortic growth ≥ 3mm/year, patients had a higher KE ratio.

Conclusion

Our study suggests that 4D flow MRI is a promising tool for TBAD evaluation that can provide information beyond traditional MRA or CTA. 4D flow has the potential to become an integral aspect of TBAD work-up, as hemodynamic assessment may allow earlier identification of at-risk patients who could benefit from earlier intervention.