Size of the proximal neck in AAAs treated with balloon-expandable stent-grafts: CTA findings in mid- to long-term follow-up.

PURPOSE: To determine the evolution of the proximal aortic neck diameter in mid- to long-term follow-up after endovascular aneurysm repair of abdominal aortic aneurysm (AAA) with a balloon-expandable stent-graft. METHODS: Thirty patients (27 men; average age 71 years, range 56-87) with infrarenal AAAs were treated with the SETA-Latecba balloon-expandable stent-graft (6 aortomonoiliac and 24 bifurcated configurations). Follow-up ranged from 4 to 8 years (mean 73.4 months). Computed tomography was done systematically before the procedure, after implantation (1-3 months), at 1 year, and annually thereafter. The last follow-up scan was utilized to measure the proximal neck for purposes of comparison with baseline and the initial post-implant scans. RESULTS: Five patients died during follow-up of causes unrelated to the procedure. No endoleaks or graft migrations were observed. The pre-deployment proximal neck diameter (a) averaged 23.4 mm (range 18-32), the diameter after deployment of the stent-graft (b) averaged 24.9 mm (range 18-34), and the most recent follow-up proximal neck measurement (c) averaged 23.8 mm (range 18-31). Comparing the last follow-up to the post-implant measurements (c-b), the neck diameter decreased in 15 (50%) patients [7 with short necks (i.e., <15 mm)] and remained unchanged (no variation) in 15 (50%) patients (4 with short necks). All patients treated with the SETA-Latecba balloon-expandable stent-graft showed stability of the proximal aortic neck diameter in mid- to long-term follow-up. CONCLUSION: The study showed that the diameter reached at initial deployment did not increase further in the long term, which supports the safety and reliability of this modular balloon-expandable stent-graft and illustrates that this device does not produce dilatation of the proximal neck after deployment. Future dilatation of the aortic neck is unlikely, and consequently, migration or delayed type I endoleak are also unlikely.

Analysis of explanted Latecba modular stent-grafts deployed transrenally to repair AAAs with short necks in 29 dogs.

Twenty-nine modular stent-grafts deployed transrenally to repair AAAs with short necks in dogs were harvested at autopsy of the animals after scheduled durations of implantations of 10 days, one month, three months, and six months. Analyses of the explanted devices included non-destructive techniques such as gross observations, X-rays CT scan, IVUS and angioscopy. Further to appropriate dissection, histological investigations were carried out by means of scanning electron microscopy (SEM) and light microscopy. All the 29 specimens were extensively encapsulated with fibrous tissues but the fibrous capsule was thin in six of them; four capsules were ulcerated. The X-rays confirmed the stability of the devices that were still straight (12), slightly bent (12) or bent (4). The modules were misaligned in only one case. IVUS and angioscopy confirmed the patency of all the stent-grafts with thin internal capsules both proximally and distally with variable capsulation in the mid-section of the grafts. The left renal artery orifices were found to be patent at dissection with no obstruction to flow. The luminal flow surface of the stent-grafts was smooth and glistening proximally and distally containing endothelial like cells and vasa-vasorum. Poor healing was noted in the aneurysm area. Transrenal deployment of this modular stent-graft is feasible and gave excellent results with regard to biofunctionality and biocompatibility. The device proved to be safe and efficient.

Transrenal deployment of a modular stent graft to repair AAAs with short necks: experiments in dogs.

Severely angulated (> 60 degrees ) or short (< 15 mm) proximal necks remain significant anatomical limitations for endovascular stent-graft repairs for abdominal aortic aneurysms. Ensuring proper proximal fixation of the stent-graft to the host artery without the short-or long-term risks of endoleak or migration represents a particular technical challenge for these anatomical circumstances. An innovative balloon expandable stent combined with a weft-knitted prosthesis was specifically designed for these situations by modelling the stent to the neck anatomy without overdistension or potential barotrauma allowing better incorporation of the device. The Latecba stent-graft consists of a 2 parts modular design. The first one, Module A, is deployed at the transrenal level and consists of a Palmaz type stent whose first half is bare and second half is sutured to a crimped weft-knitted polyester graft whose distal end holds a constriction. The second Module B is a non-crimped weft-knitted graft attached to 2 stainless steel stents. The first stent is entirely contained in the proximal textile tube, allowing fixation to module A. The second stent, which is left uncovered over the distal third, ensures proper fixation of the stent-graft distally. Following the creation of a prosthetic aneurysm in the infrarenal aorta in 32 dogs, 29 received the Latecba stent-graft for scheduled durations of 10 days, 1 month, 3 months and 6 months. Proper deployment of the stent-grafts was achieved without difficulty. All 29 animals survived and the devices were all patent at sacrifice. No device defects or migrations were observed and the stent-grafts proved to be efficient in this setting to exclude the aneurysm. Analyses of the explanted devices (gross observations, RX, CT scan, IVUS, angioscopy) confirmed the stability of this modular stent-graft. Further on-going clinical investigations are warranted to validate this concept before this stent-graft becomes commercially available without any restriction.