ABSTRACT
Surgical bypass techniques are used in the treatment of distal diffuse arterial occlusion. Despite limitations, infrainguinal endovascular intervention has dramatically increased as primary therapy as well as post-failure surgical intervention for claudication and CLI. New endovascular tools are being developed to cross occlusions, remove thrombus, and open vessels. Crossing long total occlusions is challenging. There have been several devices developed for crossing when available guidewires and catheters fail. A guidewire using optical reflectometry for guidance and radiofrequency ablation to cross is being evaluated.18 Excimer laser catheters (CliRpath, Spectranetics, Colorado Springs, CO) advanced via a “step by step” technique are also used for crossing.8,19 Blunt dissection devices (Frontrunner XP CTO Catheter System, LuMed, Johnson & Johnson, Piscataway, NJ) mechanically spread the lumen of the vessel to allow crossing.20 Re-entry tools with or without ultrasonic guidance allow the interventionalist to puncture back into the vessel lumen.21 Devices to mechanically remove the clot alone or in conjunction with thrombolytics are crucial. Some devices actually aspirate thrombus, others macerate then aspirate, and the excimer laser photoablates the thrombus.14,19,22,23 Balloons, atherectomy devices, and stents are the therapeutic cornerstones:
● Balloons: in addition to standard balloons, cutting balloons, and cryoballoons are being evaluated to lessen dissection and future intima hyperplasia.24,25
● Atherectomy: directional plaque excision allows directed excision and removal of plaque (up to 6 mm) (SilverHawk®
catheter, Fox Hollow Technologies, Redwood City, CA).26,27
● Stents: in the SFA and popliteal arteries self-expanding nitinol stents are used. Stents may be bare metal, medicated, or covered. At the time of writing, several FDA-approved stents for PAD in the limbs include the Zilver vascular stent (Cook, Bloomington, IN, 2006), Viabahn endoprosthesis (W.C. Gore & Associates, Newark, DE, 2005), Intrastent stent (EV3, St. Paul, MN, 2004), SMART and SMART Control nitinol stent system (Cordis, Warren, NJ, 2003), Intra Coil self-expanding peripheral stent (Sulzer Intratherapeutics, St Paul, MN, 2002), Wallstent iliac endoprosthesis (Boston Scientific, Natick, MA, 1996), Palmaz balloon-expandable stent (Cordis, Warren, NJ, 1991). Stents that are longer, more flexible, and more fracture-resistant, can achieve better wall apposition, and be more accurately delivered are all being developed. There is great interest in what role medicated stents may have but there are no FDA-approved drug-eluting stents for limb vessels.28,29
The results of three clinical trials published in 2006 (Laser Angioplasty for Critical Limb Ischemia (LACI), Catheter-Based Plaque Excision with SilverHawk® in Critical Limb Ischemia, and Percutaneous Transluminal Angioplasty for Treatment of “Below-the-Knee” Critical Limb Ischemia, all using endovascular therapy in CLI patients, concluded the following.
