Endograft Technology: Highlights of the past 10 Years

The past decade has seen the evolution of an exciting technology that has changed forever the treatment of aortic aneurysmal disease. From rather crude homemade stent-grafts constructed in the surgical suite to elegant commercially manufactured devices in a variety of configurations and sizes, the aortic endograft has experienced a meteoric rise in popularity to become a beneficial, minimally invasive therapy that can obviate the risk of rupture and death. There are now 3 approved endovascular devices on the market for infrarenal abdominal aortic aneurysm repair, and it is likely that additional and improved devices will become available in the future. This review revisits the developmental history of the aortic endograft, noting the ongoing refinements that have arisen from our experiences with the growing population of stent-graft patients. Although research continues to search for solutions to the problems of endoleak and migration, long-term results even with the earlier second and third-generation devices are better than has been achieved with open surgical repair.

Three-Year Experience with Modular Stent-Graft Devices for Endovascular AAA Treatment

Purpose:

To evaluate feasibility and present early results of endovascular abdominal aortic aneurysm (AAA) exclusion using modular stent-grafts.

Methods:

In a 3-year period ending July 1997, 201 patients were treated with self-expanding stent-grafts for AAAs with infrarenal necks ≥ 10 to 15 mm long and ≤ 32 mm wide; subtotal mural thrombus, calcification, and even angulation to some extent were acceptable, as were iliac arteries up to 18 mm wide. The patients were treated with either the Stentor/Vanguard device (178 cases) or the Talent endograft (23 cases). Follow-up on all patients was conducted at 3, 6, 12, 18, and 24 months.

Results:

The technical aneurysm exclusion rate was 89% (178/201). There were 18 primary endoleaks (9.0%; 2 proximal, 16 distal), 4 (2.0%) conversions to open surgery, and 1 (0.5%) failure to deploy the graft. Seven (3.5%) patients died in the perioperative period, 5 due to multiorgan failure early in the series and two of hemorrhagic complications. Five (2.5%) renal artery occlusions were encountered; in one case, the graft was removed after 3 weeks. Nineteen late endoleaks were found in follow-up, related primarily to the iliac limb graft extensions of the Stentor device, graft material problems, or unknown causes. To date, 10 primary and 13 secondary endoleaks have been treated endovascularly. Twenty (10.0%) graft-limb thromboses were treated either by thrombolysis, thrombectomy, or a femorofemoral bypass.

Conclusions:

Endovascular grafting is technically feasible and becomes easier with improvements of the introducer systems and the grafts. The seemingly high complication rate in this series is due to the liberal patient selection criteria.

Experience with the Stentor Endograft at Four Italian Centers

Purpose:

To report the outcome of an Italian multicenter trial of endovascular abdominal aortic aneurysm (AAA) exclusion using the Stentor device.

Methods:

Between April 1995 and July 1996, 66 patients (63 men; average age 69 years, range 53 to 84) with infrarenal AAAs meeting the inclusion criteria were enrolled. The average diameter of the aneurysm was 4.6 cm (range 4.2 to 7). Three (4.5%) of the 66 AAAs were anastomotic aneurysms.

Results:

Sixteen (25%) tubular and 50 (76%) bifurcated endograft procedures were attempted; 4 (6.1%) were converted and 1 terminated owing to technical faults with the bifurcated graft's second limb. One tube graft was too short and failed to exclude an anastomotic aneurysm. Sixty (91%) endograft procedures were completed successfully. Six (9.1%) vascular complications occurred, three in one patient who subsequently died of pulmonary embolism 72 hours postoperatively (1.5% mortality). There were four (6.1%) proximal endoleaks; two sealed spontaneously in < 1 month, and a third was converted (7.6% conversion rate). The fourth is being observed. Clinical success (aneurysm exclusion with no death or endoleak) at 30 days was 86.3% (57/66). In the 23-month follow-up of 57 eligible patients, 2 patients died of unrelated causes and 1 graft limb thrombosed, requiring a crossover femoral bypass. One patient was converted to surgical repair at 5 months postoperatively when increasing aneurysm size signaled an undisclosed endoleak (1.8% late conversion rate). Five other secondary endoleaks were treated with endovascular techniques.

Conclusions:

The Stentor was technically feasible in 10% to 40% of AAA candidates in this study, although deployment of the second limb was problematic in the bifurcated device. Introduction of the second-generation Vanguard endograft brought this study to an end.

Endoluminal aortic grafting with renal and superior mesenteric artery incorporation by graft fenestration

PURPOSE

To explore the use of juxta- and suprarenal aortic segments for endograft fixation in abdominal aortic aneurysm (AAA) patients and to develop methods of graft implantation that use endograft fenestrations to preserve renal and visceral vessel perfusion.

METHODS

From August 1998 to May 2000, 13 AAA patients with unsuitable infrarenal aortic necks were treated with custom-designed endovascular grafts employing the juxta- and suprarenal aortic segments for proximal sealing. Flow to 33 renal and superior mesenteric arteries was maintained via graft fenestrations that were aligned by use of radiopaque graft markers. The fenestration-orifice interface for renal arteries was secured with modified balloon-expandable stents.

RESULTS

All fenestrated grafts were deployed as planned, and all target vessels (33/33) were preserved. Two patients did not receive any stents, one being the first in the series and another who had incorporation of a renal accessory artery only. Without the use of transgraft stenting, 5 renal arteries would have been occluded by the endograft or poorly perfused. Procedural success was 100%. No conversion to open operation or graft-related complications occurred. There was no primary endoleak in any patient by angiographic criteria. Two patients required additional surgical procedures related to access vessels. Periprocedural mortality at 30 days was nil. Follow-up ranging from 3 to 24 months on all patients has not demonstrated any proximal or distal endoleaks. One stented renal vessel has occluded; all other arteries remain patent at last examination.

CONCLUSIONS

This study has demonstrated the ability to successfully place a multifenestrated endoluminal graft in an aortic aneurysm using juxta- and suprarenal aortic segments to obtain a satisfactory seal. Stenting of the fenestration-renal ostium junction has helped to maintain renal patency.

Slimgraft: a percutaneous endovascular graft system

PURPOSE

To describe an in vitro feasibility trial of a new percutaneous endograft delivery technique.

METHODS AND RESULTS

A water flow model of 9-mm (inner diameter) transparent plastic tubing was used to test the feasibility of sequentially delivering the components of an endograft through a 7-F sheath for assembly in situ. The tubular endovascular graft was fabricated from a 10-mm x 68-mm Wallstent and 50-microm-thick Dacron graft. The graft material was formed into a tube, attached with a suture to a guidewire, and delivered into the plastic tubing. The Wallstent was then delivered through the tubular graft and deployed, affixing the graft to the plastic tube wall. In 4 trials, only 1 attempt was not successful.

CONCLUSIONS

These concepts and techniques may have implications in the development of percutaneously deliverable endovascular grafts.