Specific shortcomings of endograft design

Further to the rapid enlargement of an aneurysm to 5.6 cm in diameter after 3 years of surveillance, a 79-year-old patient was fitted with a Vanguard modular stent graft and monitored on a regular basis for 6 years. Two years later, the aneurysmal sac ruptured. The patient died 1 month after an open surgery. The device was devoid of any encapsulation and the ipsilateral limb was detached from the body. The Nitinol skeleton was mostly maintained, however, some polypropylene sutures were broken. The resulting motion of the sharp-angled Nitinol wires caused abrasion and resulted in a few localized holes that were sufficient to permit blood to percolate through the textile wall. Some polyester yarns in the warp direction were ruptured. The Nitinol wire used in this device was shown to be corrosion resistant but the selection of the polypropylene suture was inappropriate. Because this technology is maturing rapidly, these weaknesses can be avoided in the future generations of endovascular devices. It is recommended that these Nitinol wires be sutured to the fabric and that polyester yarns stronger than 68 decitex in tubes 8 mm in diameter are selected.