Plaque Excision with Distal Protection: A Logical Next Step for Superficial Femoral Artery SilverHawk Atherectomy

J INVASIVE CARDIOL 2009; 21:11-12 Endovascular treatment for peripheral vascular disease continues to evolve.1,2 Among the many devices available for endovascular intervention, atherectomy offers several potential advantages. SilverHawk atherectomy (ev3, Inc., Plymouth, Minnesota) allows plaque excision, a gradual and progressive increase in lumen size and, in many patients, can be used as standalone therapy obviating the need for balloon angioplasty and/or stent placement. As the SilverHawk atherectomy device is advanced through the lesion, plaque is excised and then captured within the distal nosecone. The device can then be rotated so that the cutting element is directed toward additional plaque within the arterial wall. The device is removed from the body and the captured debris is removed from the distal nosecone. Additional atherectomy is then performed to achieve the desired angiographic result. Successful acute angiographic results can be achieved in approximately 75% of patients with stand-alone SilverHawk atherectomy.3 Initial studies using SilverHawk atherectomy showed procedural success rates of 98%, complication rates of less than 5% and primary patency rates of 80% at 6 months.4 Although atherectomy continues to gain acceptance as an effective treatment option for superficial femoral artery (SFA) intervention, potential complications include distal embolization, impaired distal flow and potential distal vessel occlusion. These complications are particularly important in patients with single vessel runoff and, in this setting, may result in threatened limb loss. Therefore, the ability to prevent distal embolization is a logical next step to improve the safety of SilverHawk atherectomy. Although embolic protection devices have been used successfully in many different vascular beds, they have not been adequately studied during lower extremity endovascular interventions (Table 1). The incidence of clinically significant distal embolization during lower extremity intervention is estimated to be approximately 5% and asymptomatic distal embolization most likely occurs more frequently.5 In 2006, Suri et al published a series of 10 patients undergoing SilverHawk atherectomy of the SFA and popliteal arteries in whom distal protection with the FilterWire EX and EZ Models (Boston Scientific Corp., Natick, Massachusetts) were used.6 The majority of patients had TASC B lesions and 6/10 patients had either one- or two-vessel distal runoff. All patients were found to have macroscopic debris within the filter that ranged in size from 0.5 to 10 mm in length. In one case, no-flow occurred following atherectomy that resolved after removal of the filter that was filled with macroscopic debris. Based upon this small series, the authors concluded that distal embolization during SilverHawk atherectomy is common and can be effectively treated using embolic protection devices. Shammas et al reported the results of a single-center, prospective registry (PROTECT) evaluating the use of distal protection during angioplasty, stenting and SilverHawk atherectomy.7 Forty patients with 56 lesions were treated for infrainguinal disease; 43 lesions were treated with angioplasty and stenting and 13 lesions received SilverHawk atherectomy. Either the Spider FX (ev3) or EmboShield (Abbott Vascular, Redwood City, California) distal protection devices were used in all patients. Clinically significant debris was found in 45% of patients and was more frequently in those undergoing SilverHawk atherectomy, compared to angioplasty/stenting (91% versus 28%, p 0.2 cm) occurred in 7/14 (50%) of patients. Debris that was removed from the nosecone ranged in size from 0.1 to 0.4 cm. When comparing the components of the captured debris to the embolized debris, there were significant differences. The captured debris contained macrophages, cholesterol, collagen/fibrosis, calcification and a small proportion had fibrin; the embolized debris contained mainly macrophages, cholesterol and collagen/fibrosis. Fibrin and calcification were infrequent findings within the embolized debris. Given that the majority of patients had debris captured by the embolic protection devices, the authors were unable to identify any clinical or angiographic predictors of distal embolization. The authors failed to mention whether any clinically significant distal embolization occurred in the patients studied. Of note, no patients within this series had complete SFA occlusion; it would be anticipated that in the setting of a chronic SFA occlusion, more plaque, debris and thrombus could potentially be embolized during the SilverHawk atherectomy procedure. To summarize the issue of distal embolization during SilverHawk atherectomy, several points from the published literature are evident: 1) asymptomatic distal embolization documented by the presence of debris within a distal protection device or embolic signals recorded from a Doppler probe occur in the vast majority of patients; 2) SilverHawk atherectomy can be safely performed using a distal embolic protection device (FilterWire EZ or Spider FX); 3) patients with single vessel runoff tolerate clinically significant distal embolization poorly and therefore have the potential for threatened limb loss, and; 4) clinically significant distal embolization with loss of distal vessels and/or impaired distal flow occurs infrequently. Additional, larger studies are needed to more completely define the benefit of embolic protection devices during SilverHawk atherectomy. Taking this information into perspective, distal embolic protection should be considered with SilverHawk atherectomy in the setting of single-vessel runoff and those with long lesions that would require prolonged atherectomy runs.

1. Mahmud E, Cavendish JJ, Salami A. Current treatment of peripheral arterial disease: Role of percutaneous interventional therapies. J Am Coll Cardiol 2007;7;50:473–490.
2. Rogers JH, Laird JR. Overview of new technologies for lower extremity revascularization. Circulation 2007;116:2072–2085.
3. Ramaiah V, Gammon R, Kiesz S, et al. Midterm outcomes from the TALON Registry: Treating peripherals with SilverHawk: Outcomes collection. J Endovasc Ther 2006;13:592–602.
4. Zeller T, Rastan A, Schwarzwalder U, et al. Percutaneous peripheral atherectomy of femoropopliteal stenoses using a new-generation device: Six-month results from a single-center experience. J Endovasc Ther 2004;11:676–685.
5. McDermott JC, Crummy AB, Voegeli DR, Starck EE. Complications of transluminal angioplasty. Radiology 1987;162:286–288.
6. Suri R, Wholey MH, Postoak D, et al. Distal embolic protection during femoropopliteal atherectomy. Catheter Cardiovasc Interv 2006;67:417–422.
7. Shammas NW, Dippel EJ, Coiner D, et al. Preventing lower extremity distal embolization using embolic filter protection: Results of the PROTECT registry. J Endovasc Ther 2008;15:270–276.
8. Lam RC, Shah S, Faries PL, et al. Incidence and clinical significance of distal embolization during percutaneous interventions involving the superficial femoral artery. J Vasc Surg 2007;46:1155–1159.
9. Baim DS, Wahr D, George B, et al. Randomized trial of a distal embolic protection device during percutaneous intervention of saphenous vein aorto-coronary bypass grafts. Circulation 2002;105:1285–1290.
10. Halkin A, Masud AZ, Rogers C, et al. Six-month outcomes after percutaneous intervention for lesions in aortocoronary saphenous vein grafts using distal protection devices: Results from the FIRE trial. Am Heart J 2006;151:915–917.
11. Mauri L, Cox D, Hermiller J, Massaro J, et al. The PROXIMAL trial: Proximal protection during saphenous vein graft intervention using the Proxis Embolic Protection System: A randomized, prospective, multicenter clinical trial. J Am Coll Cardiol 2007;50:1442–1449.
12. Gray WA, Hopkins LN, Yadav S, et al. Protected carotid stenting in high-surgical-risk patients: The ARCHeR results. J Vasc Surg 2006;44:258–268.
13. Yadav JS, Wholey MH, Kuntz RE, et al. Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med 2004;351:1493–1501.
14. Henry M, Klonaris C, Henry I, et al. Protected renal stenting with the PercuSurge GuardWire device: A pilot study. J Endovasc Ther 2001;8:227–237.
15. Hagspiel KD, Stone JR, Leung DA. Renal angioplasty and stent placement with distal protection: Preliminary experience with the FilterWire EX. J Vasc Interv 2005;16:125–131.