Stent Graft System Treats Thoracoabdominal Aortic Aneurysm

A minimally invasive stent graft repairs thoracoabdominal aortic aneurysm (TAAA), a complex condition that causes the aorta to bulge into the abdomen.

The Medtronic (Dublin, Ireland) Valiant TAAA Stent Graft System is comprised of a thoracic bifurcation and visceral manifold graft, which work together to facilitate endovascular stenting of the visceral vessels--the renal, celiac, and superior mesenteric arteries--while maintaining blood flow to the visceral and infrarenal segments. The complexity of the design required the use of computational fluid dynamics simulations in order to create a geometrically correct model of each graft relative to the same aorta coordinates and positioning in the body trunk, as well as the arteries that feed the organs and extend into the legs.

The system is comprised of several sections that interlock into each other proximally. The topmost level includes a thoracic bifurcated graft and a visceral manifold that creates four visceral vessels. Each of the branch vessels is stented individually by bridging stents, which can thereafter accept further descending extensions. An infrarenal graft stent and iliac extensions are also available. Once flow has been secured to each of the involved branches, the open limb of the proximal compartmentalizing graft is extended distally, excluding the diseased segment of vessel.

“Taking the complex and making it simple has long been our goal for the treatment of TAAAs. Working with Medtronic could eventually place our solution in the hands of vascular surgeons around the world to help patients facing a life-threatening condition,” said vascular surgeon Patrick Kelly, MD, of Sanford Health (Sioux Falls, SD, USA), who developed the concept. “We hope that this will have a major impact on the treatment of one of the most challenging disease processes to face our specialty.”

TAAA results from continuous dilation of the descending thoracic aorta, which extends into the abdominal aorta. Degradation of structural proteins such as collagen and elastin, or a defect in their composition, leads to medial degeneration and weakening of the aortic wall. Subsequent dilatation results from hemodynamic forces on the arterial wall, as well as intrinsic changes in the composition of the arterial wall itself, which cause the diameter of the aorta to expand further and increase wall tension, thus creating a vicious cycle.