In-situ laser fenestration of endovascular stent-graft in abdonimal aortic aneurism repair (EVAR)

Endovascular abdominal aortic aneurysms (AAA) repair (EVAR) involves the minimally invasive implantation of a stent-graft within the aorta to exclude the aneurysm from the circulation and thus preventing its rupture. The feasibility of EVAR is highly dependent on the aorta morphology: the presence of one or more renal arteries emerging from the aneurysm is the absolute limit for the implantation of a standard stent-graft. Classical intervention methods involves the implantation of a custom-made graft with fenestrations, leading to extremely complicated surgeries with high risks for the patient and high costs. More recent techniques introduced the use of standard grafts (i.e. without fenestrations) with mechanical in-situ fenestration, but this procedure is limited principally by the brittleness and low stability of the environment, in addition to the difficult of guidance of the endovascular tools due to the temporarily block of blood flow. In this work we propose an innovative EVAR strategy which involves in-situ fenestration with a fiber guided laser tool, controlled via an electromagnetic 3D navigation system. The proposed strategy is based on the integration of a laser system into an electromagnetic navigation platform, which includes sensorized catheters and guidewires simultaneously tracked. The aim is to provide the surgeon with a selective fenestration tool whose position and orientation can be accurately tracked and showed in real time within a 3D virtual model of the patient vasculature. Such a model can be reconstructed from volumetric radiological images acquired just before the endograft deployment, allowing the surgeon to visualize the collateral arteries during the entire surgical procedure, also after endograft deployment. Results of preliminary fenestration tests on graft-materials will be presented, including the effect of blood and tissues.