Performance of the Gore VBX Balloon Expandable Endoprosthesis as Bridging Stent-Graft in Branched Endovascular Aortic Repair for Thoracoabdominal Aneurysms

PURPOSE

Bridging stent stability is crucial for efficacy and safety of branched aortic endovascular repair (bEVAR) of thoracoabdominal aortic aneurysms (TAAAs). In this study, we assess the performance of the new Viabahn Balloon-Expandable endoprosthesis (VBX) in bEVAR. Based on our learning curve we give recommendations for a safe and effective use of the device.

MATERIALS AND METHODS

We prospectively collected the data of patients with TAAAs undergoing bEVAR between December 2017 and December 2019. All patients with implantation of at least 1 VBX stent-graft as bridging stent were included in our single-center analysis. Demographic, comorbidity, and computed tomography angiography (CTA) data of 112 patients were retrospectively evaluated. Primary endpoint was a composite of branch-related technical success and freedom from target vessel instability. Secondary endpoints were clinical and ongoing clinical success.

RESULTS

Primary endpoint: technical success was achieved in all patients (100%) with a freedom from target vessel instability of 96.3% after a median follow-up of 18 months. Overall mortality was 13.4% (n=15) and 13 patients underwent secondary interventions, 12 of them are still alive and 1 suffered from aneurysm sac expansion, consequently an ongoing clinical success of 75.9% was reached. After modification of the implantation technique during the course of the study by selecting longer stent lengths after accurate estimation of vessel curvature and expected adaptation of the flexible endoskeleton to the specific anatomical conditions, no type Ic endoleaks were observed in the last 70 cases.

CONCLUSIONS

The VBX stent-graft can be safely used as bridging stent for branched thoracoabdominal repair. However, learning curve should be considered to avoid type Ic endoleak and edge stenosis. Based on this experience longer landing zones and 2-step deployment of VBX are useful for successful bridging also of challenging target vessels.

Fatigue Resistance of the Advanta V12/iCast and Viabahn Balloon-Expandable Stent-Graft as Bridging Stents in Experimental Fenestrated Endografting

PURPOSE

Bridging stents undergo millions of cycles during respiratory movements of the kidneys throughout the patient's life. Thus, understanding the response of fabric and endoskeleton of the stent to cyclic loading over the time is crucial. In this study, we compare the fatigue resistance of the Viabahn Balloon-Expandable stent-graft (VBX) with the widely used Advanta V12/iCast under prolonged stress induction.

MATERIALS AND METHODS

A polyester test sheet with 10 fenestrations was used simulating a fenestrated endograft. Five 6×59 mm VBX stent-grafts and five 6×58 mm Advanta stent-grafts were implanted into 6×6 mm fenestrations. The stents were flared with a 10×20 mm PTA (percutaneous transluminal angioplasty) catheter and connected with a fatigue stress machine. All stent-grafts were evaluated by microscopy and radiography at baseline and after regular intervals until 50,000,000 cycles were applied, simulating a life span of approximately 75 months. Freedom from fracture (FF), freedom from initial polytertafluoroethylene (PTFE) changes (FIC), and from PTFE breakpoint (FBP, all-layer defect) were calculated.

RESULTS

Digital radiographic images did not show any stent fracture in both groups after 50,000,000 cycles. The VBX stent-graft was free from any all-layer defects at the conclusion of 50,000,00 cycles resulting in a significant higher FBP compared with Advanta V12 (50,000,000 vs 33,400,000; p<0.01). All-layer defects were observed only in the Advanta group. Two of 5 Advanta stents showed early penetration of the nitinol ring causing a defect of PTFE. Regarding FIC, there was no significant difference between the stents (3,400,000 in VBX vs 3,200,000 in Advanta).

CONCLUSIONS

In fatigue tests simulating respiration movements, VBX and Advanta V12 performed equally well in terms of fracture resistance and freedom from initial PTFE changes. VBX maintained freedom from PTFE breakpoint throughout the full 50,000,000 cycles. All-layers defects were detected only in Advanta and were mainly caused by penetration of the nitinol ring through the PTFE.

Zenith TX2LowProfile TAA Endovascular Graft: a next generation thoracic stent-graft

AIM

The aim of the present article is to describe a new thoracic stent graft (Zenith TX2 Low-Profile TAA Endovascular Graft).

METHODS

Feasibility of endovascular repair of thoracic aortic aneurysms depends on several anatomic factors. A primary limitation is an adequate arterial approach. Since most currently used endografts require large introducer sheaths, patients with severely diseased iliofemoral vessels are often excluded from this less-invasive technique. Attempts to overcome access difficulties increase the risk for arterial access-site complications such as aortoiliac rupture. In addition, highly angulated proximal landing zones provide challenges in obtaining proximal graft conformance and sealing.

RESULTS

The introduction of next-generation endografts such as the Zenith TX2LowProfile TAA Endovascular Graft provides a solution for a larger number of patients, including those with small vessels, vascular access problems and tortuous aortic anatomy.

CONCLUSION

The ongoing Zenith TX2 Low-Profile Endovascular Graft trial will build further understanding of the performance of the device allowing for treatment of a wider patient population.

Endovascular surgery as a bridge solution for selected vascular emergencies

Vascular emergencies patients present with several problems requiring immediate sufficient evaluation of the situation and intervention in order to save life, limb, or a serious health injury. Endovascular surgery may be very useful as bridging technique in order to obtain immediate bleeding control. Additionally, a remarkable number of patients has poor general health conditions and is unfit for open repair. The surgical solution would be invasive and prohibitive for this high-risk patient's subgroup. Endovascular techniques play an important role in the management of vascular emergencies. They allow treatment to be rapidly coupled with diagnosis, especially beneficial parameter for traumatic injuries. In particular, embolization is a well-established technique for hemostasis and is preferable when intervention for bleeding pelvic fractures is necessary. Additionally, in case of significant tissue destruction and contamination in the vicinity of the injury vascular access by endovascular techniques may be advantageous. Finally, endovascular balloon occlusion for vascular control may be used as an adjunct to surgery when conventional exposure is technically challenging and hazardous. The objectives of this review article are to highlight the utility of endovascular surgery in vascular emergencies and to compare current treatment options of urgent clinical entities, based on the literature.