Customized aortic repair : an alternative approach to aortic aneurysm repair using injectable elastomer

Despite the rise of EVAR as treatment concept for abdominal aortic aneurysms during the last two decades, this concept is not flawless. For only a selection of the aneurysms is treatable with the current EVAR grafts, due to unfavourable neck morphology and distal anatomy. Furthermore, many complications such as endoleaks do occur after EVAR, leading to stringent follow-up programs with many harmful imaging studies and a great number of secondary interventions. To overcome the anatomical limitations and potentially many of the procedure related complications, a novel treatment concept called Customized Aortic Repair (CAR) has been devised: a method of excluding the aortic aneurysm using endovascular techniques to inject a biocompatible elastomer into the aneurysm sac. The non-polymerised liquid elastomeric solution is used to fill the aneurysm sac around a balloon-catheter. After the in situ polymerisation and balloon deflation, an endoluminal mould with a patent lumen excludes the aneurysm sac. The potential of this treatment concept has been investigated in this thesis. Experiments described in this thesis taught us that filling the aneurysm sac with the elastomer in an in-vitro circulation model diminished wall movement and thereby wall-stress significantly, underlining the potential of the treatment concept. In the same circulation model, the elastomer was successfully used to exclude type II, III and IV endoleaks. Besides the several in-vitro experiments, the feasibility of the concept was tested in an in__vivo porcine experimental model (n=3). In these preliminary experiments, the aneurysms of all three pigs were successfully excluded with the elastomer. Dislodgement tests in a tensile testing machine showed that EVAR grafts (Excluder, Endurant and Anaconda), when inserted in a neck shorter then 15 mm, can be dislodged from a bovine artery sample easily. The largest force was needed to dislodge the Anaconda. When the area between the aneurysm model and the graft was filled with elastomer, the dislodgement force increased significantly with all grafts with 139-1016%. Filling the aneurysm sac with elastomer may prove to be a useful adjuvance to EVAR, diminishing the chance of graft dislodgement and type I endoleak. As the elastomer will be used endovascular, the direct contact with blood requires a low thrombogenicity of the elastomer to prevent occlusive thrombosis or embolization. The thrombogenicity of this new elastomer was tested in a validated ex- vivo model and compared to ePTFE to validate its feasibility in vivo. No significant difference in FPA production and platelet activation was observed between elastomer and ePTFE grafts (p>0.05). By scanning electron microscopy, numerous platelet aggregates were observed on the ePTFE grafts whereas just a few adhered platelets and no aggregates were observed in the elastomer grafts. This thesis underlines the large potential of the CAR-treatment concept, but also discusses its limitations.UBL - phd migration 201

The effect of short aneurysm neck length on the proximal fixation strength of modern EVAR-grafts. An in vitro study

Study of the normal and pathological locomotory syste

Influence of aneurysm wall stiffness and the presence of intraluminal thrombus on the wall movement of an aneurysm. An in-vitro study

Vascular Surger

The Proximal Fixation Strength of Modern EVAR Grafts in a Short Aneurysm Neck. An In Vitro Study

Objectives: The study aims to measure the strength of the proximal fixation of endografts in short and long necks. Design: Three types of endografts were compared: Gore Excluder (R), Vascutek Anaconda (R) and Medtronic Endurant (R). Materials and methods: The proximal part of the stent grafts was inserted in bovine arteries and the graft was then attached to a tensile testing machine. The force to obtain dislodgement (DF) from the aorta was recorded for each graft at proximal seal lengths of 10 and 15 mm. Results: The median OF (interquartile range, IQR) for the Excluder, the Anaconda and the Endurant with a seal length of 15 mm was: 11.8 (10.5-12.0) N, 20.8 (18.0-30.1) N and 10.7 (10.4-11.3) N. With the shorter proximal seal of 10 mm, DF was, respectively: 6.0 (4.5-6.6) N, 17.0 (11.2-36.6) N and 6.4 (6.1-12.0) N. Conclusions: The proximal fixation of the Anaconda is superior to the Excluder and the Endurant at short necks of 10 and 15 mm in an experimental set-up. There is a statistically significant decrease of proximal fixation for the Excluder stent graft, when decreasing the length of the proximal neck from 15 to 10 mm. (C) 2009 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved

Influence of aneurysm wall stiffness and the presence of intraluminal thrombus on the wall movement of an aneurysm - an in vitro study

Vascular Surger

Aortic Customize: An In Vivo Feasibility Study of a Percutaneous Technique for the Repair of Aortic Aneurysms Using Injectable Elastomer

Objective: This study aimed to test a percutaneous technique for aneurysm-sac filling by means of in situ polymerisation in an in vivo model. Design: Aortic Customize is a new endovascular treatment concept for aortic aneurysms: a non-cross-linked liquid elastomer is injected to fill the aneurysm sac around a balloon-catheter. With this method, a compliant elastomer mould with a patent lumen is created. Material: The formulation used in the experiments consisted of a two-component addition-cure liquid-silicone formulation, based on vinyl-terminated polydimethylsiloxane (PDMS). Methods: The concept of aneurysm-sac filling was tested in vivo in porcine experiments (n = 3). Results: In vivo porcine experiments with the sac-filling application showed successful exclusion of the created aneurysms with patent lumens and absence of endoleaks. The aneurysms were excluded successfully in the in vivo model, injecting elastomer through a 7-French catheter, filling up the entire aneurysm sac. Conclusions: These in vivo experiments demonstrate that the principle of aneurysm-sac filling by means of in situ curing is feasible, excluding the aneurysm and creating a new lumen. Further long-term animal experiments must be done prior to consideration of clinical application. (C) 2010 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.Vascular Surger