Editor's note: See Dr. Walker's video message accompanying this month's editorial.
In this issue of Vascular Disease Management you will find useful clinical articles, a novel case report, and a letter to the editor on peripheral vascular research. This month I would like to comment on the burgeoning use of covered stent grafts for the treatment of occlusive superficial femoral arterial (SFA) disease in peripheral vascular interventions.
Dr. Weinstock provides a current review of the literature. He includes a review of the recent iterative device modifications and a practical guide with tips about utilizing these devices to achieve better clinical outcomes. Stent grafts now represent about 30% of the SFA/popliteal stent utilization. Whereas some of this represents usage in cases of popliteal artery aneurysm, arteriovenous fistulae, and perforations, the majority is in cases of occlusive disease. From a technical standpoint these devices are easy to use.
For SFA cases, they can be placed through 6 Fr sheaths and are now available in lengths of up to 25 cm. A simple ripcord release mechanism enables very predictable and precise placement with no fear of the stent “jumping.” These stents are profoundly fracture resistant and the PTFE serves as a barrier to intimal ingrowth. Long-term results have improved in recent studies perhaps secondary to stent modification (ends of the stent trimmed to avoid redundant PTFE, and anticoagulant bonding).
Perhaps as important has been a sizing algorithm to avoid oversizing and undersizing as these stents tend to fail secondary to stenosis at either end rather than within the body of the stent. Perhaps the most encouraging data with these stent grafts show that there is no profound patency change when treating longer lesions. Encouraging data are emerging in the use of these stent grafts to treat recurrent bare metal in-stent restenosis.
Recent data have shown that abrupt thrombotic closure is less of a problem than practitioners had originally feared, perhaps due to better stent graft design, sizing, anticoagulant bonding, or a better understanding of the role of surveillance and proactive treatment of edge restenosis prior to graft failure. Limitations of stent grafts must also be appreciated. These devices have a higher initial cost than conventional nitinol stents.
These devices should only be utilized when appropriate vessel expansion can be achieved during intervention. If these are placed in areas of profound elastic recoil that is greater than the stent graft’s radial force, luminal compression will occur. As with any surgical graft there must be good vascular outflow. These devices should not be used in vessels smaller than 4.5 mm. It is imperative that the patient be able to tolerate an antiplatelet regimen, which should probably be considered as a long term need. Thrombosis of stent grafts usually does not result in acute limb ischemia, but if it does it must be treated as an emergency.
I am encouraged by the recent data with covered stents. Is it possible that with future modifications these will prove to be the answer for the perplexing problem of SFA restenosis?