In vitro feasibility of a sac-sealing endoprosthesis in a double chimney graft configuration for juxtarenal aneurysm.

PURPOSE: To investigate in an in vitro juxtarenal aneurysm flow model the feasibility and efficacy of using a sac-sealing endoprosthesis in a chimney graft configuration. METHODS: In two experiments, a Nellix sac-sealing endoprosthesis was used as the main graft in a double-branched chimney graft configuration, using a self-expanding Viabahn stent-graft and a balloon-expandable Advanta V12 stent-graft in a pressurized silicone juxtarenal aneurysm flow model. In two consecutive experiments, the chimney graft balloons were inflated (1) at the beginning of and (2) to simulate varying renal ischemic times half-way through the injection of the sac-sealing polymer into the Nellix endobags. The balloons and were kept inflated until the endobags were filled and the polymer was cured. The aneurysm model was connected to a roller pump, pumping gelatin-water at a rate of 100 beats per minute. Before and after 24 hours of continuous flow, computed tomography (CT) scans were made using contrast injection. The CT scans were reconstructed and analyzed for gutter cross-sectional area, total gutter volume, chimney graft compression, and volume of space between the aneurysm wall and the endoprosthesis. RESULTS: Differences in gutter size between both types of chimney grafts were minimal. Chimney graft compression exceeded 50% if the balloons were inflated in the chimney grafts halfway through polymer injection into the endobag. Twenty-four hours of flow did not influence chimney graft patency or gutter size. CONCLUSION: In a juxtarenal aneurysm flow model, we demonstrated the technical feasibility of a sac-sealing endoprosthesis in a chimney graft configuration. This early evidence suggests that balloon dilation of chimney grafts should occur over the entire period of polymer injection and curing to prevent considerable chimney graft compression.

A proof-of-concept in vitro study to determine if EndoAnchors can reduce gutter size in chimney graft configurations.

PURPOSE: To investigate the feasibility of using endoanchor technology to reduce chimney graft-related gutter size in a juxtarenal aneurysm model. METHODS: In silicone juxtarenal aortic aneurysm models with two sizes of branch arteries and two sizes of aorta, single chimney graft (CG) configurations were constructed using 6-mm Atrium balloon-expandable stent-grafts in association with two sizes of Gore Excluder main grafts (23 and 28.5 mm). Configurations without Aptus EndoAnchors, with suprarenal placement of EndoAnchors, and with additional infrarenal placement of EndoAnchors were investigated. A total of 12 CG configurations were scanned using 64-slice computed tomography. Gutter volume and gutter areas at the top and bottom of the sealing zone were measured with image processing software. RESULTS: The combination of supra- and infrarenal placement of endoanchors led to a reduction in gutter volume compared to unanchored configurations. The same configurations also led to a decrease in gutter area at the bottom of the sealing zone. CONCLUSION: It is feasible to reduce gutters in CG configurations with the use of endoanchors in an in vitro juxtarenal aneurysm model.

Geometric study of various chimney graft configurations in an in vitro juxtarenal aneurysm model.

PURPOSE: To determine gutter size and stent-graft geometry in an in vitro juxtarenal aneurysm model using various chimney graft (CG) configurations. METHODS: Two silicone juxtarenal aortic aneurysm models were constructed combining different diameters of the aorta and renal artery. In a single-branched CG configuration, 2 sizes (23 and 28.5 mm) of Excluder stent-grafts were tested individually with 2 sizes of 2 types of CGs: Advanta balloon-expandable (BE) stent-grafts (6×59 and 12×61 mm) and Viabahn self-expanding (SE) stent-grafts (6×50 and 13×50 mm). All combinations were tested with a short (10-mm) and long (20-mm) sealing zone between the CG and main graft (total 16 configurations). Immediately after deployment, the CG configuration was scanned using a 64-slice computed tomography scanner. Gutter sizes were measured at different levels of the sealing zone. RESULTS: At the top of the sealing zone, the gutters were significantly larger in the BE CGs compared to SE CGs in combination with the 23-mm main graft (p=0.021). At the bottom of the sealing zone, there were no statistically significant differences (p=0.77). No significant differences were seen using the 28.5-mm main graft. Median gutter size was larger in the 6-mm CGs. The length of the sealing zone had no influence on gutter size. Significant compression of the main graft was found using 12 or 13-mm CGs compared to 6-mm CGs (p=0.001). CONCLUSION: In this in vitro study, the CG configurations with BE stent-grafts show larger gutters than configurations with SE stent-grafts in small main grafts. Main graft compression is increased using wider CG stent-grafts.