Development of analysis methods for patient specific aneurysm repair devices

The occurrence and rupture of an aneurysm in the lower abdominal artery is the tenth most likely source of death in men over the age of 55. If the existence of an aneurysm is identified then stent-like technologies have been developed over the last 10 years to allow for deployment, structural support and to provide adequate blood flow to mitigate against aneurysm wall rupture. While devices are in clinical use it has been established that most patients have a unique artery topography that requires tailored solutions. The design of such devices is in its infancy and the inability to measure the failure stress state of a device when deployed in a human artery necessitates the use of computational modelling tools. Thus the overall aim is to develop simulation tools to allow medical device manufacturers to minimise mechanical failure and to enhance the overall performance of devices that are specially tailored for patient’s anatomy. The project significantly builds upon engineering simulation methods which have been developed by Dempster and Nash in previous related research work. To date, this has primarily focussed on deformation issues of the key structural elements of the devices. The proposed research will require novel simulations to address a number of new issues for “tailored” devices which will include full device modelling, the inclusion of fluid-structure interactions and the need to address uncertainty issues in device design and deployment. This will allow the simulation techniques to be applied with real confidence in a design context. In this study the analysis techniques will be applied to devise designs of the medical device OEM Vascutek Ltd. These devices consist of tubular fabric constructions supported by a series of wire bundles wound from strands of superelastic material Nitinol. The functionality and long-term mechanical life of the device depend on an understanding of the device-artery interactions which the simulation techniques will deliver.