Early and mid-term results after endovascular repair of thoracoabdominal aortic aneurysms using the off-the-shelf multibranched t-Branch device: a national multi-center study.

Objective: The multibranched off-the-shelf Zenith® t-Branch (Cook Medical, Bloomington, IN) device is commonly chosen for endovascular repair of thoracoabdominal aortic aneurysms. The aim of this study was to report early and mid-term outcomes in all patients treated with the t-Branch in Norway; Design and Methods: A retrospective multicenter study with Norwegian centers performing complex endovascular aortic repair was undertaken. T-Branch patients from 2014 to 2020 were included. All postoperative computed tomography angiography images were reviewed, and demographic, anatomical, perioperative and follow-up data were analyzed; Results: Seventy patients were treated in a single-step (n = 55) or staged (n = 15) procedure. Symptomatic presentation was seen in 20 patients, six of which had a contained rupture. Technical success was 87% (n = 59), with failures caused by unsuccessful bridging of target vessels (n = 4), target vessel bleeding (n = 3), persisting type 1c endoleak (n = 1) and t-Branch malrotation (n = 1). 30-day mortality was 9% (n = 6) and was associated with high BMI (p = .038). The spinal cord ischemia rate was 21% (n = 15) and was associated with type II aneurysms (OR 5.4, 95% CI 1.1-26.7, p = .04), smoking (OR 6.0, 95% CI 1.3-27.6, p = .02) and intraoperative blood loss (OR 1.1, 95% CI 1.0-1.3, p = .01). Survival at one, two and three years was 84 ± 4%, 70 ± 6% and 67 ± 6%, respectively. Freedom from aortic-related reinterventions at one, two and three years was 80 ± 5%, 65 ± 7% and 50 ± 8%, respectively; Conclusion: The study showed low early mortality (9%) and satisfactory mid-term survival. Technical success was achieved in acceptable 87% of procedures. The rate of spinal cord ischemia was high, occurring in 21% of patients.

This paper provides a national experience of all TAAA patients treated with the multibranched t-Branch stent graft in Norway in a multi-center study. As we aimed at including all Norwegian patients operated with the device, the paper adds real-world data on t-Branch outcomes from four regional smaller-volume vascular centers.The paper provides technical and clinical mid-term results with several patients being followed up for >3 years.Technical success was achieved in 87% of procedures.The 30-day mortality rate was 9% and survival at one, two and three years was 85 ± 4%, 70 ± 6% and 67 ± 6%, respectively.Spinal cord ischemia was associated with Crawford type II aneurysms, smoking and intraoperative blood loss.

A Retrospective Evaluation of Intra-Prosthetic Thrombus Formation After Endovascular Aortic Repair in Cook Zenith Alpha and Medtronic Endurant II Patients.

OBJECTIVE: To investigate the occurrence of limb graft occlusion (LGO) and intra-prosthetic thrombus (IPT) formation in Zenith Alpha and Endurant II stent graft limbs. METHODS: A single centre retrospective study was conducted on patients treated with the Zenith Alpha and Endurant II stent grafts between 2017 and 2019. All post-operative computed tomography angiography images were re-investigated for thrombus formation. Demographic, aneurysm, and stent graft data were collected and compared. LGO was defined as complete occlusion or significant stenosis (≥ 50% lumen diameter reduction). Logistic regression on pro-thrombotic risk factors was conducted. Freedom from LGO and overall limb IPT were compared using Kaplan-Meier analyses. RESULTS: Seventy-eight Zenith Alpha and eighty-six Endurant II patients were studied. The median follow up was 33 (IQR 25, 44) months for Zenith Alpha patients and 36 (IQR 22, 46) months for Endurant II patients (p = .53). LGO was seen in 15% (n = 12) of Zenith Alpha patients and 5% (n = 4) of Endurant II patients (p = .032), and freedom from LGO was significantly higher among Endurant II patients (p = .024). The Zenith Alpha stent graft was an independent risk factor for LGO (OR 3.9, 95% CI 1.1 - 13.4; p = .032). Among Zenith Alpha patients, limb flare compression within the main body gate was over represented in LGO patients (p = .011). There was no difference in freedom from overall limb IPT between the stent graft systems. For Endurant II limbs, IPT was significantly less common in the integrated ipsilateral limbs (without ETLW/ETEW stent graft limbs) (p = .044). Main endograft body IPT was correlated with overall limb IPT (p = .035). CONCLUSION: LGO was significantly more common among Zenith Alpha than Endurant II patients. Zenith Alpha limbs was an independent risk factor for LGO. There was no difference between stent grafts in overall limb IPT formation.

Aortic roadmapping during EVAR: a combined FEM-EM tracking feasibility study.

PURPOSE: Currently, the intra-operative visualization of vessels during endovascular aneurysm repair (EVAR) relies on contrast-based imaging modalities. Moreover, traditional image fusion techniques lack a continuous and automatic update of the vessel configuration, which changes due to the insertion of stiff guidewires. The purpose of this work is to develop and evaluate a novel approach to improve image fusion, that takes into account the deformations, combining electromagnetic (EM) tracking technology and finite element modeling (FEM). METHODS: To assess whether EM tracking can improve the prediction of the numerical simulations, a patient-specific model of abdominal aorta was segmented and manufactured. A database of simulations with different insertion angles was created. Then, an ad hoc sensorized tool with three embedded EM sensors was designed, enabling tracking of the sensors' positions during the insertion phase. Finally, the corresponding cone beam computed tomography (CBCT) images were acquired and processed to obtain the ground truth aortic deformations of the manufactured model. RESULTS: Among the simulations in the database, the one minimizing the in silico versus in vitro discrepancy in terms of sensors' positions gave the most accurate aortic displacement results. CONCLUSIONS: The proposed approach suggests that the EM tracking technology could be used not only to follow the tool, but also to minimize the error in the predicted aortic roadmap, thus paving the way for a safer EVAR navigation.

Prediction of guidewire-induced aortic deformations during EVAR: a finite element and in vitro study.

Introduction and aims: During an Endovascular Aneurysm Repair (EVAR) procedure a stiff guidewire is inserted from the iliac arteries. This induces significant deformations on the vasculature, thus, affecting the pre-operative planning, and the accuracy of image fusion. The aim of the present work is to predict the guidewire induced deformations using a finite element approach validated through experiments with patient-specific additive manufactured models. The numerical approach herein developed could improve the pre-operative planning and the intra-operative navigation. Material and methods: The physical models used for the experiments in the hybrid operating room, were manufactured from the segmentations of pre-operative Computed Tomography (CT) angiographies. The finite element analyses (FEA) were performed with LS-DYNA Explicit. The material properties used in finite element analyses were obtained by uniaxial tensile tests. The experimental deformed configurations of the aorta were compared to those obtained from FEA. Three models, obtained from Computed Tomography acquisitions, were investigated in the present work: A) without intraluminal thrombus (ILT), B) with ILT, C) with ILT and calcifications. Results and discussion: A good agreement was found between the experimental and the computational studies. The average error between the final in vitro vs. in silico aortic configurations, i.e., when the guidewire is fully inserted, are equal to 1.17, 1.22 and 1.40 mm, respectively, for Models A, B and C. The increasing trend in values of deformations from Model A to Model C was noticed both experimentally and numerically. The presented validated computational approach in combination with a tracking technology of the endovascular devices may be used to obtain the intra-operative configuration of the vessels and devices prior to the procedure, thus limiting the radiation exposure and the contrast agent dose.

Midterm Outcomes for Endovascular Repair of Thoraco-Abdominal Aortic Aneurysms.

Objective: To investigate technical and clinical outcomes in patients with thoraco-abdominal aortic aneurysms treated with the multibranched off the shelf Zenith t-Branch stent graft or a custom made device (CMD). Methods: A retrospective study was conducted of patients operated on at a single tertiary vascular centre in Norway. Twenty eight t-Branch and 17 CMD patients were identified. Demographic, aneurysm, and peri-operative data were summarised and compared. Results: Thirty day mortality was 4% (2/45), with mortality rates of 7% (2/28) and 0 in t-Branch and CMD patients, respectively (p = .52). Technical success was 87% (39/45), with a non-significant difference between t-Branch and CMD procedures of 89% (25/28) and 82% (14/17), respectively (p = .63). Stent graft coverage was significantly longer in t-Branch patients (p = .020). Paraparesis or paraplegia developed in 18% (5/28) of t-Branch patients and 12% (2/17) of CMD patients (p = .69), and spinal cord ischaemia was associated with Crawford type II aneurysms (p = .010) and aortic coverage >400 mm (p = .050). The estimated survival at one and two years for t-Branch patients was 93% and 88%, and 100% and 92% for CMD patients. Freedom from re-intervention was estimated at 70% and 43% at one and two years for t-Branch patients, and 58% and 50% for CMD patients. Conclusion: The study showed low 30 day mortality rates, acceptable technical success rates, high medium term survival, and no statistically significant differences in clinically relevant outcomes between t-Branch and CMD patients.