Keynote
DESIGNING NOVEL POLYMERIC ENDOVASCULAR DEVICES

Endoluminal therapies aim at treating lumen-related pathologies in a broad range of clinical areas, such as the GI tract, the trachea-bronchial tree and the vasculature. This talk will present a new strategy, able to markedly reduce the insertion profile of endoluminal devices, by sequentially deploying their different components and rapidly welding them together at their site of performance. Even though this strategy is of broad clinical applicability, this concept is exemplified in this lecture by focusing on the treatment of Abdominal Aortic Aneurysms (AAA). The formation of aneurysms is a very dangerous degenerative pathology of arterial tissues, whereby the wall of the artery weakens locally, markedly expands and, if ruptures, it typically leads to death.

An endoluminal device consisting of a vascular graft mounted on a metallic stent (‘stent graft’) and deployed intra-luminally at the aneurysmal site using a balloon, was introduced in 1991. Being minimally invasive, whenever applicable, this became the procedure of choice. Unfortunately, though, these devices can be implanted in only around 60% of AAA repair patients, primarily due to the bulkiness and rigidity of these bi-component metallo-polymeric stent grafts.

This lecture introduces in situ weldable devices for AAA repair, whereby the two components of the stent graft are separated, deployed sequentially and welded together at the aneurismal site. By doing so, a remarkable reduction of the large profile of the existing stent grafts, to as little as half their current dimensions, is obtained. The composition of various in situ weldable polymers, mainly polyurethane elastomers, exhibiting the required low softening temperature and able to weld at physiologically acceptable temperatures, were fine tuned. The devices were successfully implanted in pigs, demonstrating the clinical feasibility and simplicity of the in situ welding concept.