A Novel Method for Treatment of Abdominal Aortic Aneurysms Using Percutaneous Implantation of a Newly Designed Endovascular Device
Authors: Ruiz Carlos E. , Zhang He Ping , Douglas Jayne T. , Zuppan Craig W. , Kean Charles J.C. 
Published: June 2012

Background
Percutaneous implantation of a stent to bridge abdominal aortic aneurysm (AAA) may provide an alternative to surgical reconstruction in patients with this serious disorder. We developed a self-expandable, stainless steel, woven mesh endovascular device with a delivery catheter and studied its efficacy in a canine model of AAA.

Methods and Results
Infrarenal AAAs were created surgically in eight adult dogs using autologous tissue. Two types of endovascular stents were used in this study: a plain or uncovered stent, about 14 mm in diameter in the unconstrained configuration, and a covered stent, coated by porous polyurethane, about 16 mm in diameter. All stents were successfully placed on the first attempt. Aortograms revealed a mean aneurysm diameter of 1.86±0.47 cm, an average of 70% larger than the reference aortic lumen before stent placement. After stent placement, aortograms showed that the aneurysmal cavity disappeared completely in three dogs treated with a covered stent and that the aortic blood flow into the cavity markedly reduced, with faint contrast filling the cavity in the remaining five dogs treated with an uncovered stent. The uncovered stent was intentionally placed across the major arterial branches in two dogs. No acute complications were encountered at the time of stent placement. Two dogs were killed shortly after the procedure for immediate evaluation of the device, which was found to be in place and patent. One dog in which a covered stent was placed was euthanized 2

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weeks later because of paraplegia secondary to a spinal cord infarction noted 48 hours after stent placement. Postmortem study revealed thrombus occluding the stent lumen. The remaining five dogs tolerated the devices well and completed 4 weeks of follow-up. Premortem aortograms showed no residual aneurysmal cavity in four dogs and only a small cavity in one dog that had received an uncovered stent. All stents were fully patent with no thrombus and were either completely or partially surfaced by neointima. Importantly, the major arterial branches over which the uncovered stents were placed were widely patent without obstruction by neointima.

Conclusions
This study demonstrates the feasibility of percutaneous implantation of this new device and its effectiveness in the treatment of surgically created AAA in our canine model. The covered stent was able to exclude AAA immediately upon deployment and is of potential value in the emergency treatment of leaking AAAs. The uncovered stent appears to safely bridge branch arteries as well as significantly reduce the angiographic size of the aneurysm and may be useful in the elective therapy of AAAs. These results are promising, and future clinical trials to investigate the safety and efficacy of this device in humans are warranted.