Type 1b Endoleaks After Thoracic Endovascular Aortic Repair are Inadequately Reported: A Systematic Review

Background: Complications after thoracic endovascular aortic repair (TEVAR) are common. Even after a successful TEVAR, a late endoleak (>30 days) can occur. The objective of this study is to summarize the current evidence and, if lacking, the need of evidence regarding the incidence and predictive factors for type 1b endoleak in patients with aortic aneurysm treated with TEVAR. Methods: A systematic review of the literature was performed on endoleak type 1b, in patients with aortic aneurysm, after TEVAR. The PubMed and Embase databases were systematically searched for articles regarding endoleak type 1b up to January 2019. The main subjects discussed are the incidence, risk factors, treatment, and prognosis. Results: About 722 articles were screened, and 16 articles were included in this review. The reported incidence of endoleak is between 1.0% and 15.0%, with a mean follow-up duration of at least 1 year. Type 1b endoleak is associated with an increased aortic tortuosity index (>0.15 cm−1). No significant difference is found in relation to age and gender. Treatment is required in most cases (22/27) and is usually performed with distal extension of the stent graft (21/27). There are no data regarding stent graft oversizing, length of distal landing zone, and differences between devices or the prognosis for patients with type 1b endoleak. Conclusions: Limited literature is available on the occurrence of type 1b endoleak after TEVAR. A tortuous aorta can be associated as a predictive factor for the occurrence of type 1b endoleak. Data clearly delineating the anatomic variables predicting type 1b endoleak should be examined and listed. Likewise, the impact of more recent conformable devices to prevent complications like type 1b endoleaks from occurring should be elucidated

Tortuosity of the Descending Thoracic Aorta in Patients with Aneurysm and Type B Dissection

Objective: Tortuosity in the descending thoracic aorta (DTA) comes with aging and increases the risk of endoleaks after TEVAR. With this report, we would like to define and classify tortuosity in the DTA of patients with thoracic aortic disease. Methods: Retrospective case–control study of two hundred seven patients, comparing sixty-nine controls without aortic disease (CG), to sixty-nine patients with descending thoracic aortic aneurysm (AG) and sixty-nine patients with type B aortic dissection (DG). 3Mensio Vascular software was used to analyze CTA scans and collect the following measurements; tortuosity index, curvature ratio and the maximum tortuosity of the DTA. The DTA was divided into four equal zones. The maximum tortuosity was divided into three groups: low (60°). Results: Compared to the CG, tortuosity was more pronounced in the DG, and even more in the AG, evidenced by the tortuosity index (1.11 vs. 1.20 vs. 1.31; p < 0.001), curvature ratio (1.00 vs. 1.01 vs. 1.03; p < 0.001), maximum tortuosity in degrees (28.17 vs. 33.29 vs. 43.83; p < 0.001) and group of tortuosity (p < 0.001). The maximum tortuosity was further distal for the DG and AG, evidenced by the zone of maximum tortuosity (4A vs. 4B vs. 4B; p < 0.001). Conclusion: This study shows that tortuosity in the DTA is more prominent in diseased aortas, especially in aneurysmal disease. This phenomenon needs to be taken into account during planning of TEVAR to prevent stent graft-related complications and to obtain positive long-term outcome

Midterm outcomes and evolution of gutter area after endovascular aneurysm repair with the chimney graft procedure

Objective: The objective of this study was to describe our experience with endovascular aneurysm repair (EVAR) with the use of chimney grafts for branch vessel preservation. Methods: Patients treated with a chimney graft procedure between October 2009 and May 2015 were included for analysis. Patients who were not considered eligible for open surgical repair or for conventional, branched, or fenestrated endovascular repair were selected. A standardized operating procedure with left brachial or axillary artery cutdown access for the chimney grafts and bilateral femoral artery cutdown access for the aortic main device was used. Outcomes were noted according to the Society for Vascular Surgery reporting standards. In addition, evolution of gutter area over time was determined. Estimated rates of survival, freedom from aneurysm growth, and clinical success at 24 months of follow-up were calculated. Results: Thirty-three patients (mean age, 77.6 ± 6.8 years; 87.9% male) with a mean preoperative maximum aneurysm diameter of 71.7 ± 13.5 mm were included. A total of 54 of an intended 54 chimney grafts were deployed. Primary technical success and 30-day secondary clinical success rates were 87.9% and 84.8%, respectively. The early mortality rate was 6.1% (n = 2). The early type Ia endoleak rate was 6.1% (n = 2), and the chimney graft occlusion rate was 6.1% (n = 2). Median follow-up duration was 26 months (interquartile range, 14.8-37.3 months). The estimated 2-year actuarial survival rate was 78.1% (standard error, ±7.4%). Late complications included type Ia endoleak (n = 1), chimney graft occlusion (n = 2), type II endoleak with aneurysm growth (n = 4), and distal stent graft limb kinking and occlusion (n = 1). Late reinterventions included coil or glue embolization (n = 3), distal limb extension (n = 2), open endoleak ligation (n = 2), Palmaz stent placement (n = 1), repeated EVAR (n = 1), and femorofemoral bypass graft (n = 1). At 2 years, the estimated secondary clinical success and freedom from aneurysm growth rates were 80.5% (±7.2%) and 84.4% (±7.2%). Gutter size showed a small but significant decrease over time at the level of the proximal markers and at 10 mm distal from the markers. Conclusions: Midterm results show that a standardized procedure for EVAR using chimney grafts for branch vessel preservation is an acceptable option for high-risk patients with large, complex aneurysms who are unfit for open repair and who have been excluded from fenestrated EVAR. Gutter size decreases over time, but the rate of branch vessel loss and reinterventions demonstrate that this approach should remain reserved for those who are at truly prohibitive risk for open or fenestrated stent graft repair

Stent-Graft Deployment Increases Aortic Stiffness in an Ex Vivo Porcine Model

Background Aortic stiffness is an independent predictor of cardiovascular mortality. In this study, the effect of thoracic endovascular aortic repair (TEVAR) on aortic stiffness is investigated by measuring aortic pulse wave velocity (PWV) in an ex vivo porcine model. Methods Fifteen fresh porcine thoracic aortas were connected to a benchtop pulsatile system. Intraluminal pressures were recorded in the ascending aorta and at the celiac trunk using a needle connected to a pressure sensor. The distance between the needles was divided by the time difference between the base of the pressure peaks to calculate aortic PWV at baseline and after stent-graft deployment and distal stent-graft extension. Results Mean aortic PWV was 5.0 m/s at baseline. PWV increased by 4% after proximal stent-graft deployment (P = 0.09) and by 18% after stent-graft extension (P < 0.001). Pulse pressure in the nonstented ascending aorta increased by 11.0 ± 1.2 mm Hg after proximal stent-graft deployment (P < 0.001) and by 17.3 ± 1.5 mm Hg after stent-graft extension (P < 0.001). The increases in PWV and pulse pressure showed a positive linear correlation with the percentage of stent-graft coverage (P < 0.001 and P < 0.001). Conclusions In this experimental setup, aortic stiffness increased after stent-graft deployment, dependent on the percentage of the aorta that was covered by stent graft. These results show that TEVAR leads to significant changes in aortic hemodynamics, which merits evaluation in the clinical setting

Impact of thoracic endovascular aortic repair on radial strain in an ex vivo porcine model

OBJECTIVES: To quantify the impact of thoracic endovascular aortic repair (TEVAR) on radial aortic strain with the aim of elucidating stent-graft-induced stiffening and complications. METHODS: Twenty fresh thoracic porcine aortas were connected to a mock circulatory loop driven by a centrifugal flow pump. A highdefinition camera captured diameters at five different pressure levels (100, 120, 140, 160, and 180 mmHg), before and after TEVAR. Three oversizing groups were created: 0-9% (n = 7), 10-19% (n = 6), and 20-29% (n = 6). Radial strain (or deformation) derived from diameter amplitude divided by baseline diameter at 100 mmHg. Uniaxial tensile testing evaluated Young's moduli of the specimens. RESULTS: Radial strain was reduced after TEVAR within the stented segment by 49.4 ± 24.0% (P < 0.001). As result, a strain mismatch was observed between the stented segment and the proximal non-stented segment (7.0 ± 2.5% vs 11.8 ± 3.9%, P < 0.001), whereas the distal non-stented segment was unaffected (P = 0.99). Stent-graft oversizing did not significantly affect the amount of strain reduction (P = 0.30). Tensile testing showed that the thoracic aortas tended to be more elastic proximally than distally (P = 0.11). CONCLUSIONS: TEVAR stiffened the thoracic aorta by 2-fold. Such segmental stiffening may diminish the Windkessel function considerably and might be associated with TEVAR-related complications, including stent-graft-induced dissection and aneurysmal dilatation. These data may have implications for future stent-graft design, in particular for TEVAR of the highly compliant proximal thoracic aorta