Reverse Cheese-Wire Septotomy to Create a Distal Landing Zone for Thoracic Endovascular Aortic Repair

Purpose: The objective of this study is to describe a novel method for creating a distal landing zone for thoracic endovascular aortic repair (TEVAR) in chronic aortic dissection. The technique is described in a patient with prior total arch and descending aortic replacement, with false lumen expansion. Technique: A cheese-wire endovascular septotomy was desired to create a single lumen above the celiac axis. To avoid dividing the septum caudally across the visceral segment, we performed a modified septotomy in a cephalad direction. Stiff wires were passed into the prior surgical graft, through true lumen on the right and false lumen on the left. An additional wire was passed across an existing fenestration at the level of the celiac axis, and snared and externalized. 7F Ansel sheaths were advanced and positioned tip-to-tip at the fenestration. Using the stiff wires as tracks, the through-wire was pushed cephalad to endovascularly cut the septum. Angiogram demonstrated successful septotomy, and TEVAR was performed to just above the celiac with successful aneurysm exclusion and no endoleak or retrograde false lumen perfusion. Follow-up computed tomography angiogram (CTA) showed continued exclusion without false lumen perfusion. Conclusions: This novel modification in a reverse direction provides an alternative method for endovascular septotomy, when traditional septotomy may threaten the visceral vessels.

Early Clinical Outcomes of the Active Seal Technology of the AFX Endovascular Aortic Aneurysm System With the VELA Cuff for Patients With a Conical Proximal Neck

Purpose: To evaluate the efficacy of the Active Seal technology employed in the AFX endovascular aortic aneurysm system (AFX), during endovascular aneurysm repair (EVAR) in patients with abdominal aortic aneurysms (AAAs) having a conical proximal neck. Materials and Methods: A retrospective analysis of the EVAR for AAA with a conical proximal neck using the AFX was performed at 17 Japanese hospitals between January 2016 and August 2020. The conical proximal neck was defined as a cone-shaped proximal neck, with more than 10% diameter increase within a 15 mm length at the proximal landing zone. All anatomical analyses were performed in the core laboratory, and cases with parallel walls within the proximal neck adequate for the landing zone were excluded from the study. Results: This study included 53 patients, but only 39 patients (mean age, 76.6 ± 6.7 years; 87.0% males; mean aneurysm diameter, 52.0 ± 8.0 mm) were analyzed after being characterized as having a pure conical neck by the core laboratory. The mean proximal neck diameters at the lower renal artery and proximal edge of the aneurysm were 20.0 ± 2.9 mm and 27.5 ± 4.9 mm, respectively. The mean proximal neck length was 21.5 ± 6.0 mm. Instructions for use violations other than the conical neck were observed in 15 patients (38.5%). The VELA cuff was used in all cases; however, additional proximal cuff was required in 9 more cases (23.1%). The Active Seal technology was able to significantly extend the proximal sealing zone from 21.5 ± 6.0 to 26.0 ± 12.2 mm ( p = .047). Thirty-six patients completed the 12-month follow-up (one patient was lost to follow-up, and 2 patients died from causes unrelated to the aneurysm), and there were no type-1a and 3 endoleaks with only one reintervention (2.6%) related to type 1b endoleak in the 12-month period. Furthermore, there was no significant enlargement of the proximal neck diameter at 12 months (at 1 month: 20.6 ± 3.4 mm and at 12 months: 21.3 ± 3.8 mm; p = .420). Conclusion: The Active Seal technology of the AFX significantly extended the proximal seal zone and no type-1a endoleak and proximal neck dilation was observed in patients with conical proximal neck at 12 months.

Hydraulic Fracture Treatment and Landing Zone Interval Optimization: An Eagle Ford Case Study

This paper focuses on optimizing future well landing zones and their corresponding hydraulic fracture treatments in the Eagle Ford shale play. The optimum landing zone and stimulation treatment were determined by analyzing multiple landing zone options, including the lower Austin Chalk, Eagle Ford, and Pepper Shale, with several hydraulic fracturing treatment possibilities. Fracturing fluids and their volume, proppant size, and cluster spacing were investigated to determine the optimum hydraulic fracturing treatment for the subject geologic area. Ranges of 75,000 to 300,000 gallons of pure gel, pure slickwater, and hybrid fracturing fluids along with 20/40, 30/50, 40/70, and 100 mesh proppant were tested. Cluster spacing of twenty feet to eighty feet were also sensitized in this study. A fully three-dimensional hydraulic fracture modeling software was used to develop a geological and geomechanical model of the studied area. The generated model was calibrated with available field data to ensure that the model reflects the area's geological and geomechanical characteristics. The developed model was used to create fracture results for each sensitized parameter. Production analysis was performed for all fracture models to determine the optimum landing zone and fracturing treatment implications. The study shows that the Eagle Ford had better production than the lower Austin Chalk in the subject area. The Pepper Shale had the highest potential hydrocarbon production, around 326 Mbbl cumulative, when fractured with a pure gel treatment. The analyses showed that a hybrid treatment with 70% gel and 30% slickwater yielded the optimum production due to the treatment economics even though the highest production was obtained using the pure gel. Treating the formation with larger proppant provided better production than smaller proppant due to conductivity concerns associated with damaging mechanisms in the studied area. Since increasing the volume above 175,000 gallons caused a negligible increase in the production, 175,000 gallons of fracturing fluid per stage appeared to be the optimum fracturing fluid volume. Thirty-foot cluster spacing was the optimum spacing in the study area. Overall, the study suggests that oil production can be improved in the Eagle Ford study area through a detailed workflow development and optimization process. The hydraulic fracture treatment and landing zone optimization workflow ensures optimum hydrocarbon extraction from the study area. The developed workflow can be applied to new unconventional plays instead of using trial and error methods.

Stratigraphic Characterization of the Eagle Ford Shale to Identify the Best Landing Zone: A Semi-analytical Workflow

Placement of the horizontal well within the best landing zone is critical to maximize well productivity, thus identification of the best landing zone is important. This paper illustrates an integrated semi-analytical workflow to carry out the stratigraphic characterization of the Eagle Ford shale to identify the best landing zone. The objective of this work is twofold: 1) to establish a workflow for stratigraphic characterization and 2) to understand the local level variability in the well performance.To establish the workflow, we have used the production data, petrophysical information and regional reservoir property maps. As a first step of the workflow, we subdivided the Eagle Ford shale into nine smaller stratigraphic units using the wireline signatures and outcrop study. In the second step, we have used statistical methods such as linear regression, fuzzy groups and theory of granularity to capture the relationship between the geological parameters and the well performances. In this step, we identified volume of clay (Vclay), hydrocarbon filled porosity (HCFP) and total organic carbon (TOC) as key drivers of the well performance. In the third step, we characterized the nine smaller units and identified four stratigraphic units as good reservoirs with two being the best due to their low Vclay, high HCFP and high TOC content.Finally, we reviewed the well paths of four horizontal wells with respect to the best stratigraphic units. We observed that production behavior of these wells is possibly driven by their lateral placement. The better producing wells are placed within the middle of the best stratigraphic units whereas the poor wells are going out the best stratigraphic units. This investigation provides a case study that demonstrates the importance of integrating datasets to identify best landing zones and the suggested workflow can be applied to other areas and reservoirs to better identify targetable zones.

Modular Endo-Bentall Procedure Using a “Rendez-Vous Access”

Purpose: The concept of a single endovascular valve-carrying conduit device was designated endo-Bentall, but published experience is limited to a single case. This technical note describes an alternative modular endo-Bentall technique and a novel access technique to implant it. Technique: A 82-year-old woman with chest pain referred for a 10 cm symptomatic aneurysm of the distal arch and descending aorta. An ascending aortic aneurysm of 5.5 cm prevented endovascular aortic arch repair due to lack of a proximal landing zone. The technique is a modular approach combining a physician-modified endograft (PMEG) with 3 large fenestrations for coronary artery perfusion and a transcatheter aortic valve implantation (TAVI). A “rendez-vous access” with a transapical and transfemoral through-and-through wire offered rapid sequential deployment in a modular fashion of both components. The PMEG was deployed first, landing 5 mm deep in the left ventricular outflow tract (LVOT) and the transcatheter aortic valve was implanted few millimeters below. The endo-Bentall procedure was combined with endovascular aortic arch repair. Conclusion: A modular endo-Bentall procedure combining a PMEG and TAVI is feasible and adaptable to emergent setting using the “rendez-vous access.”

Evaluation and Analysis of Dust Storm Activity in Tianwen-1 Landing Area Based on the Moderate Resolution Imaging Camera Observations and Mars Daily Global Maps

The first Mars exploration mission from China (Tianwen-1) was launched on 23 July 2020 with the goal of “orbiting, landing, and roving”. The occurrence of dust storm activities is an important criterion of assessing atmospheric risk for the Tianwen-1 landing process. Dust storm activities from Mars Year (MY) 24 to MY32 in southern Utopia Planitia were identified. Most dust storms only appeared in one Mars Daily Global Map (MDGM), with a lifetime of less than or equal to solar longitude (Ls) = 0.5°. Only if the lifetime of a dust storm is greater than or equal to Ls = 1° can it reach the primary landing ellipse. From Ls = 0–50°, dust storms are mostly in the diffusion stage with a maximum speed of movement of 2479 km/Ls. Then, the speed gradually decreases to the minimum value of 368 km/Ls when the dust storm is in the dissipation stage. If a dust storm moves at an average speed of 750 km/Ls, the safe landing zone is a circle within a radius of 750 km centered on the primary landing ellipse. From March to May 2021, eight dust storms were identified in the Moderate Resolution Imaging Camera (MoRIC) mosaics. Because there was no dust storm activity in MoRIC mosaic on 13 May 2021, we concluded that there would be no dust storm in the primary landing ellipse on 15 May (MY36, Ls = 45.1°). Therefore, the landing time of the Tianwen-1 probe was finally determined as 15 May, which successfully landed in the south of the Utopia Planitia, and the in-situ investigation was carried out by the Zhurong Mars rover.

Safety and Effectiveness of TEVAR in Native Proximal Landing Zone 2 for Chronic Type B Aortic Dissection in Patients With Genetic Aortic Syndrome

Objectives The aim of this study is to report the safety and effectiveness of thoracic endovascular aortic repair (TEVAR) in a native proximal landing zone (PLZ) 2 for chronic type B aortic dissection (TBAD) patients with genetic aortic syndrome (GAS). Methods A retrospective review of a single center database to identify patients with GAS treated with TEVAR in native PLZ 2 for chronic TBAD and thoracic false lumen aneurysm between February 2012 and February 2018 was undertaken. Results In total, 31 patients with GAS (24 Marfan syndrome [MFS], 5 Loeys-Dietz syndrome [LDS], and 2 vascular Ehlers-Danlos syndrome [vEDS]) were treated by endovascular repair. Nineteen patients were treated by TEVAR as index procedures with 8 patients (5 females, mean age = 55, range = 36–79 years old) receiving TEVAR in native PLZ 2. Left subclavian artery (LSA) perfusion was preserved in all 8 patients: by left common carotid artery-LSA bypass in 6 patients, chimney stenting of the LSA in 1 patient, and partial coverage of LSA ostium in 1 patient. Technical success was achieved in all patients (100%). There was no 30 day mortality (0%). The 30 day morbidity (0%) was free from major complications. The median follow-up was 40 months (range = 7–79). One patient died due to non-aortic-related cause. Native PLZ 2 was free from complications in MFS patients (5/8). Two patients with LDS developed type Ia endoleak with aneurysmal progression. One patient was treated by proximal extension with a double inner branched arch stent-graft landing in the replaced ascending aorta. The other one was treated with frozen elephant trunk. Conclusion Thoracic endovascular aortic repair in native PLZ 2 was safe and effective with no early or midterm PLZ complications in patients with MFS with chronic TBAD in this limited series. Native PLZ 2 is not safe in patients with LDS and should only be used in emergencies as a bridging to open repair.

Pre-procedural determination of device size in left atrial appendage occlusion using three-dimensional cardiac computed tomography

The complex structure of the left atrial appendage (LAA) brings limitations to the two-dimensional-based LAA occlusion (LAAO) size prediction system using transesophageal echocardiography. The LAA anatomy can be evaluated more precisely using three-dimensional images from cardiac computed tomography (CT); however, there is lack of data regarding which parameter to choose from CT-based images during pre-procedural planning of LAAO. We aimed to assess the accuracy of measurements derived from cardiac CT images for selecting LAAO devices. We retrospectively reviewed 62 patients with Amplatzer Cardiac Plug and Amulet LAAO devices who underwent implantation from 2017 to 2020. The minimal, maximal, average, area-derived, and perimeter-derived diameters of the LAA landing zone were measured using CT-based images. Predicted device sizes using sizing charts were compared with actual successfully implanted device sizes. The mean size of implanted devices was 27.1 ± 3.7 mm. The perimeter-derived diameter predicted device size most accurately (mean error = − 0.8 ± 2.4 mm). All other parameters showed significantly larger error (mean error; minimal diameter = − 4.9 ± 3.3 mm, maximal diameter = 1.0 ± 2.9 mm, average diameter = − 1.6 ± 2.6 mm, area-derived diameter = − 2.0 ± 2.6 mm) than the perimeter-derived diameter (all p for difference < 0.05). The error for other parameters were larger in cases with more eccentrically-shaped landing zones, while the perimeter-derived diameter had minor error regardless of eccentricity. When oversizing was used, all parameters showed significant disagreement. The perimeter-derived diameter on cardiac CT images provided the most accurate estimation of LAAO device size regardless of landing zone eccentricity. Oversizing was unnecessary when using cardiac CT to predict an accurate LAAO size.

Comparison of the Outcomes of Total Endovascular Aortic Arch Repair Between Branched Endograft and Chimney Endograft Technique in Zone 0 Landing

Purpose: Zone 0 landing in thoracic endovascular aortic repair (TEVAR) has recently gained increasing attention for the treatment of high-risk patients. The aim of this study was to compare the outcomes of total endovascular aortic arch repair between branched TEVAR (bTEVAR) and chimney TEVAR (cTEVAR) in the landing zone (LZ) 0. Materials and Methods: This was a single-center, retrospective, and observational cohort study. From January 2010 to March 2020, 40 patients (bTEVAR, n=25; cTEVAR, n=15; median age: 79 years) were enrolled in this study, with a median follow-up period of 4.1 years. These patients were considered unsuitable for open surgical treatment. Results: All procedures were successful and no cases of conversion to open repair were noted during the 30-day postoperative period. The 30-day mortality was 2.5% (n=1; bTEVAR [0 of 25, 0%] vs cTEVAR [1 of 15, 6.7%]; p=0.375), the perioperative stroke rate was 10.0% (n=4; bTEVAR [4 of 25, 16.0%] vs cTEVAR [0 of 15, 0%], p=0.278), and type 1a endoleak rate was 15.0% (n=6; bTEVAR [0 of 25, 0%] vs cTEVAR [6 of 15, 40.0%], p=0.001). The risk factor for stroke was atheroma grade of ≥2 in the brachiocephalic artery (p<0.001). The risk factor for type 1a endoleak was cTEVAR (p=0.001). The 8-year survival rate was 49.9%. The aorta-related death-free rate and aortic event-free rate at 8 years were 94.4% (bTEVAR: 95.5% vs cTEVAR: 93.3%, p=0.504) and 60.7% (bTEVAR: 70.7% vs cTEVAR: 40.0%, p=0.048), respectively. Conclusions: Total endovascular aortic arch repair using bTEVAR and cTEVAR is feasible for the treatment of aortic arch diseases in high-risk patients who are unsuitable for open surgery. However, as the rate of stroke is high, strict preoperative evaluation to prevent stroke is needed. No rupture of the aneurysm was observed in cTEVAR, but patients should be selected carefully because of the high incidence of type 1a endoleak.