Endovascular aortic devices: the Parodi and Palmaz system

Based on the concept of endoluminal aneurysm exclusion, we began to develop a plan for endovascular treatment for abdominal aortic aneurysm (AAA) in 1976.Two prototypes have been developed and were marked by a high failure rate.' The first was a thin fabric graft mounted on a metallic cage-like structure composed by a self-expandable mesh with a zigzag configuration. The apparatus was compressed inside a tubular sheath, which acted as a vessel introducer and carrier. Experiments in normal canine aor- tas led to the abandonment of this prototype due to an inconsistent deployment of the metallic cage. The radial expansion properties of the cage were difficult to control and predict. Over-expansion resulted in aortic wall injury and subsequent rupture. Controversially, underexpansion led to leakage of blood be- tween the apparatus and the host aorta with subsequent device migrations. The second prototype involved a Dacron graft fitted on a Silastic bag with a cylindrical lumen, which could be distended by injection of silicone into the bag. Unfortunately, this method was associated with prompt graft thrombosis of the aorta in all experimental essays.