A New Modular Stent Graft to Reconstruct Aortic Arch

Analysis of Postoperative Remodeling Characteristics after Modular Inner Branched Stent-Graft Treatment of Aortic Arch Pathologies Using Computational Fluid Dynamics

The modular inner branched stent-graft (MIBSG), a novel interventional therapy, has demonstrated good effects in the endovascular treatment of aortic arch pathologies, especially those involving the supra-aortic branches. Nevertheless, the long-term efficacy of the MIBSG and in-depth quantitative evaluation of postoperative outcomes remain to be examined. Moreover, the regularity of postoperative vascular remodeling induced by MIBSG implantation has yet to be explored. To address these questions, we constructed four models (normal, preoperative, 1 week postoperative, and 6 months postoperative) based on a single patient case to perform computational fluid dynamics simulations. The morphological and hemodynamic characteristics, including the velocity profile, flow rate distribution, and hemodynamic parameter distribution (wall shear stress and its derivative parameters), were investigated. After MIBSG implantation, the morphology of the supra-aortic branches changed significantly, and the branch point moved forward to the proximal ascending aorta. Moreover, the curvature radius of the aortic arch axis continued to change. These changes in morphology altered the characteristics of the flow field and wall shear stress distribution. As a result, the local forces exerted on the vessel wall by the blood led to vessel remodeling. This study provides insight into the vascular remodeling process after MIBSG implantation, which occurs as a result of the interplay between vascular morphological characteristics and blood flow characteristics.

Protocol for Guo's aortIc Arch recoNstrucTion: a prospective, multicentre and single-arm study to evaluate the safety and efficacy of the WeFlow-Arch modular inner branch stent-graft system for aortic arch lesions (GIANT study)

INTRODUCTION

Endovascular repair of the entire aortic arch provides treatment opportunities for patients with aortic arch lesions who are intolerant to open surgery. However, the complex anatomical configuration, high-speed blood flow and long access from the femoral artery increase the difficulty of endovascular aortic arch repair. On the basis of our earlier studies, a new modular inner branch stent-graft system was developed specifically for lesions located in the aortic arch and part of the ascending aorta. This study aims to evaluate the safety and efficacy of the novel modular branch stent-graft system in patients with aortic arch lesions who are unsuitable for open aortic arch replacement.

METHODS AND ANALYSIS

This prospective, multicentre, single-arm, clinical trial will enrol 80 patients with aortic arch lesions requiring intervention, namely, true aortic arch aneurysms, pseudo-aortic arch aneurysms and penetrating ulcers involving the aortic arch. Clinical information and CT angiography (CTA) images will be collected and analysed to investigate the safety and efficacy of the novel modular branch stent-graft system. Patients will be followed up for 5 years. The primary outcome will be all-cause mortality and severe stroke within 12 months after the procedure. In addition, this trial will evaluate mid-term to long-term clinical and imaging outcomes through the annual clinical and CTA follow-up for 2-5 years postoperatively.

ETHICS AND DISSEMINATION

We have registered the study on a registry website (https://clinicaltrials.gov/ct2/home). The study findings will be disseminated through peer-reviewed journals, physician newsletters, conferences and the mass media.

TRIAL REGISTRATION NUMBER

NCT04765592.

Preclinical Evaluation of a Non-Customized Modular Inner Branched Stent Graft for Total Endovascular Aortic Arch Repair in a Porcine Model

OBJECTIVES

The aim of this study was to evaluate the feasibility and safety of a non-customized modular inner branched stent graft for total endovascular aortic arch repair in a porcine model.

METHODS

The modular inner branched stent graft system with a split main body design included 1 proximal main component, 1 distal main component, and 1 branched covered stent. The gutter in the proximal main component was sealed with sutured membrane. Fatigue testing was performed to evaluate the durability of the stent graft. Fifteen pigs were used in this study. In each pig, a stent graft was delivered and deployed to the aortic arch through the femoral arterial access and right carotid arterial access. Angiography and computed tomography angiography were used to evaluate the morphological features before euthanasia. After euthanasia, the implanted device, surrounding tissue, and major organs were harvested for gross and histological examination.

RESULTS

There were no collapses and no stent graft fractures detected after fatigue testing. The technical success rate was 14/15, and the incidence of major adverse cardiovascular events was 2/15. Angiography performed at the end of follow-up revealed no endoleaks and no device migration. Histological examination demonstrated excellent biocompatibility of the stent graft.

CONCLUSIONS

The non-customized modular inner branched stent graft system is safe and feasible for the endovascular reconstruction of the aortic arch in a porcine model.

A Feasibility Study of a New Unibody Branched Stent Graft Applied to Reconstruct the Canine Aortic Arch

OBJECTIVES

The aim was to evaluate the feasibility and safety of a new unibody branched stent graft for the reconstruction of the canine aortic arch.

METHODS

The unibody branched stent grafts included single branched stent grafts and double branched stent grafts. The main stent graft and branched limbs were sutured together. The branched stent grafts were folded into the introducer system, which consisted of a double channel catheter, a detachable sleeve, and an introducer sheath. The branched stent grafts were introduced and deployed into the aortic arch by the delivery system. Twenty adult mongrel dogs were used for the experiments. Ten dogs were implanted with single branched stent grafts; the other 10 were implanted with double branched stent grafts. The surviving animals were followed up for 3 months. Computed tomography angiography (CTA) was performed to observe the status of the branched stent grafts.

RESULTS

All the unibody branched stent grafts were successfully implanted into the canine aortic arches. The technical success rate was 100%. There was no cerebral infarction, paraplegia or incision infection. CTA showed that all the branched stent grafts were patent; there was no endoleak or stent migration.

CONCLUSIONS

The unibody branched stent graft system could be used to reconstruct the aortic arch. The animal experimental procedures demonstrated the safety and feasibility of the unibody branched stent graft system.

Safety and Efficacy of an Aortic Arch Stent Graft with Window-Shaped Fenestration for Supra-Aortic Arch Vessels: an Experimental Study in Swine

Background and Objectives

Thoracic endovascular aortic repair exhibits limitations in cases where the aortic pathology involves the aortic arch. We had already developed a fenestrated aortic stent graft (FASG) with a preloaded catheter for aortic pathology involving the aortic arch. FASG was suitable for elective cases.

Materials and Methods

An aortic arch stent graft with a window-shaped fenestration (FASG-W) for supra-aortic arch vessels is suitable for emergent cases. This study aims to test a FASG-W for supra-aortic arch vessels and to perform a preclinical study in swine to evaluate the safety and efficacy of this device. Six FASG-Ws with 1 preloaded catheter were advanced through the iliac artery in 6 swine. The presence of endoleak and the patency and deformity of the grafts were examined with computed tomography (CT) at 4 weeks postoperatively. A postmortem examination was performed at 8 weeks. The mean procedure time for FASG-W was 27.15±4.02 minutes. The mean time for the selection of the right carotid artery was 5.72±0.72 minutes.

Results

Major adverse events were not observed in any of the 6 pigs who survived for 8 weeks. For the FASG-W, no endoleaks, no disconnection, and no occlusion of the stent grafts were observed in the CT findings or the postmortem gross findings.

Conclusion

The procedure with the FASG-W was able to be performed safely in a relatively short procedure time and involved an easy technique. The FASG-W was found to be safe and convenient for use in this preclinical study of swine.

Safety and efficacy of a novel, fenestrated aortic arch stent graft with a preloaded catheter for supraaortic arch vessels: an experimental study in Swine

Thoracic endovascular aortic repair (TEVAR) shows limitations in cases in which the aortic pathology involves the aortic arch. The study aims were to test a fenestrated aortic arch stent graft (FASG) with a preloaded catheter for the supraaortic arch vessels and to perform a preclinical study in swine to evaluate the safety and efficacy of this device. Six FASGs with 1 preloaded catheter and 5 FASGs with 2 preloaded catheters were advanced through the iliac artery in 11 swines. The presence of endoleaks and the patency and deformity of the grafts were examined with computed tomography (CT) at 4 weeks postoperatively. A postmortem examination was performed at 8 weeks. The mean procedure time for the one and two FASG groups was 30.2 (27.9-34.5) min and 43.1 (39.2-53.7) min. The mean time for the selection of the carotid artery was 4.8 (4.2-5.5) min and 6.2 (4.6-9.4) min. Major adverse event was observed in one of 11 pigs. One pig died at 4 weeks likely because of the effects of the high dose of ketamine, while the remaining 10 pigs survived 8-week. For both the one and two FASG groups, no endoleaks, no disconnection, no occlusion of the stent grafts were observed in the CT findings and the postmortem gross findings. The procedure with the FASG could be performed safely in a relatively short procedure time and involved an easy technique. The FASG is found to be safe and convenient in this preclinical study with swine.

Diagnosis and management issues in thoracic aortic aneurysm

Thoracic aortic enlargement is an increasingly recognized condition that is often diagnosed on imaging studies performed for unrelated indications. The risk of unrecognized and untreated aortic enlargement and aneurysm includes aortic rupture and dissection which carry a high burden of morbidity and mortality. The etiologies underlying thoracic aortic enlargement are diverse and can range from degenerative or hypertension associated aortic enlargement to more rare genetic disorders. Therefore, the evaluation and management of these patients can be complex and requires knowledge of the pathophysiology associated with thoracic aortic dilation and aneurysm. Additionally, there have been important advances in the treatment available to patients with thoracic aortic disease, including an increased role of endovascular therapy. Given the risk of mortality, increased clinical recognition and advances in therapeutics, the American College of Cardiology, American Heart Association and related professional societies have recently published guidelines on the management of thoracic aortic disease. This review focuses on the pathophysiology and various etiologies that lead to thoracic aortic aneurysm along with the diagnostic modalities and management of asymptomatic patients with thoracic aortic disease.

Scalloped thoracic stent-graft for treatment of aortic arch aneurysms with unfavourable landing zones

Endovascular treatments are limited in cases of thoracic aortic aneurysms extending up or proximal to the origin of the left subclavian artery (LSCA). In such cases, the LSCA is usually either occluded or revascularised. We report our first experience of four patients who underwent thoracic aneursym treatment with new custom-made grafts with a scallop in situ for the LSCA. The graft is tailor made per case, and a re-enforced scallop is positioned proximally allowing for the stent to be deployed beyond the origin of the LSCA; the origin of the LSCA remains patent, thus negating the need for revascularisation of the head and neck vessels on the left. The stent contains markers for identifying the scallop and are located along the midline to ensure correct alignment. All of the patients who underwent this procedure had technical success with flow through the LSCA both immediately after stent deployment and on follow-up imaging. This new stent has further expanded endovascular treatment options for patients with thoracic aneurysms extending up to and beyond the LSCA, which can play a part in improving outcome and decreasing mortality rates because surgery for revascularization will not be needed.

Endografting in the aortic arch - does the proximal landing zone influence outcome?

OBJECTIVES

To analyse early and midterm results of thoracic aortic endografting (TEVAR) in the aortic arch.

METHODS

Between January 1997 and February 2009 178 patients received TEVAR in the aortic arch at our institution. This population was subdivided into four groups according to the proximal landing zone (LZ) classification in the aortic arch by Ishimaru et al. and a retrospective analysis regarding perioperative mortality, morbidity and endoleak formation was performed.

RESULTS

The overall 30-day mortality rate was 14% with no statistical significant difference between LZ's 0-3 (p=0.274). Renal insufficiency (hazard ratio (HR) 2.5; p=0.0119), age >75 years (HR 3.1; p=0.0019) and emergency procedures (HR 8.9; p < 0.0001) were independent predictors of death. There was no significant difference regarding type I (p=0.07) or type III (p=0.49) endoleaks between the proximal LZs, but a significant difference regarding the development of type II endoleaks (p=0.01).

CONCLUSIONS

The present study showed no influence of the proximal LZ on perioperative mortality and morbidity rate. Furthermore it did not influence relevant (type I/III) endoleak formation.