Joint BME and ECE Seminar: Srinivasan Varahoor, PhD

Determining the In Vivo Mechanical Boundary Conditions for the Development of the Next Generation Branched Thoracic Stent Grafts

Principal Engineer, Medtronic Endovascular Innovations

Abstract

The branched thoracic stent graft device consists of the main graft for the aorta, a branched conduit for the left subclavian artery (LSCA), and the catheter delivery system. The mechanical boundary conditions of the aorta and LSCA need to be determined for the development and testing the devices. The paucity of data on human aorta motion and the large resources needed to do prospective human motion studies are some of the challenges.

Porcine model is widely considered as an acceptable pre-clinical model for testing devices intended for the thoracic aorta arch and the branch vessels. We will quantify the threedimensional geometry and deformation in the pig's LSCA during the cardiac and respiratory cycle. The assessments are made pre- and post-implantation using cardiac-gated CTA and angiographic images. The findings allow us to

• evaluate the validity of the porcine model with respect to humans,
• correlate the fractures seen in the devices with the observed motion, and
• prescribe the boundary conditions to be applied in bench top fatigue tests.

Additionally, the methodology used for the development of bench top aorta models to test the catheter delivery system tracking and deployment will be described.

As part of the talk, an overview of Medtronic, its vascular division, and an outline of the scientific and engineering methods that drive the development and testing of endovascular devices will be given.