The filter devices have a basket that is deployed distal to the lesion. Different filters have pores of varying sizes (70–150 µm), and themselves have different diameters.10 In renal atheroembolism, cholesterol crystals are predominantly seen in the arcuate and interlobular arteries that have a diameter of 150–200 µm, where they induce inflammation leading to occlusion

of the vessel over time.11 Distal protection devices may fail to completely protect the kidney from distal atheroembolism because: (1) atheroemboli may dislodge before the device is deployed, as a guide wire must be passed across the lesion first; (2) current embolic protection devices were not designed for the renal circulation and a study comparing the length and diameter of devices to measurements of see more length and diameter of renal arteries demonstrated that few devices were compatible.12,13 5-Fluoracil mw Hence, not all procedures are able to achieve complete occlusion (and therefore protection) of the target vessel by these devices (Table 6); and (3) cholesterol crystals of smaller size than the filter pores may still deposit in distal smaller vessels and affect kidney function. An ex vivo study of aortorenal atheroma specimens examined

the distal effluent collected after each step in the angioplasty procedure.4 Cholesterol fragments of varying sizes were detected at each stage, including with initial passage of the guidewire. Fragments less than 60 µm, smaller than the filter pores, were numerous. The Cooper et al. trial randomized participants to abciximab or placebo and demonstrated some benefit in the antiplatelet therapy.7 This is important because analysis of particles demonstrates the not just cholesterol crystals, but fibrin, thrombi and platelets as well.14,15 In one study, patients receiving aspirin had lower captured particle counts.16 Antiplatelet therapy was not routinely reported in the uncontrolled studies, although more recent studies included clopidogrel, aspirin or a combination in their protocols.14,17,18

In the Cardiovascular Outcomes with Renal Atherosclerotic Lesions (CORAL) study, all participants undergoing angioplasty will receive aspirin indefinitely and clopidogrel for 4 weeks.19 In the Angioplasty and Stent for Renal Artery Lesions (ASTRAL) study, antiplatelet therapy was at the discretion of the local investigator,20 and in the Renal Atherosclerotic Revascularization Evaluation (RAVE) study, antiplatelet therapy is recommended in the medical therapy arm but not specified in the revascularization arm.21 The evidence for the use of distal protection devices currently rests solely on the one randomized controlled trial that had 1 month of follow up and is insufficient to make a guideline.