Grant: Operating Grant

Abdominal aortic aneurysm (AAA) is an abnormal dilatation of the aorta in the abdomen secondary to hypertension and atherosclerosis. Surgical treatment of AAA is increasingly being replaced by endovascular aneurysm repair (EVAR) using stent-grafts (SGs). However, the efficacy of this less invasive approach is often jeopardized by the incidence of persistent flow within the aneurysm, called endoleaks leading to aneurysm rupture if not properly detected and treated. Hence, a life long annual CT-scan surveillance is required increasing the cost of EVAR, exposing the patient to ionizing radiation and nephrotoxic contrast agent. The goal of this project is to adapt and test a new ultrasound technology called ultrasound elastography to improve patient follow-up after EVAR and ultimately avoid the use of CT-scans. This technique measures the deformation of the tissue secondary to blood pressure variation (quasi-static elastography) or to a shear wave generated by the ultrasound probe (dynamic elastography). We will optimize 2 approaches to generate elastic maps of the AAA. One approach will be a quasi-static elastography technique developed by our team giving an estimation of the deformation (strain) of the different components of the AAA by the blood pressure. The second is a dynamic elastography technique that will provide information on the elastic property of the AAA components. An optimization and validation of the 2 techniques will be first conducted in an animal model of EVAR reproducing successful EVAR and EVAR failure with endoleaks in canine abdominal aorta. Elastographic findings will be correlated to invasive pressure measurement, CT-scan and pathologic examinations. A human feasibility study will be conducted in patients with criteria of success or failure after EVAR based on CT-scan. Finally, a validation will be done in patients having EVAR and implantation of a pressure sensor to correlate the elastography maps with the pressure within the aneurysm.