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Antiplatelet pharmacotherapy for endovascular interventions has been widely adopted, with clopidogrel being one of the most common agents prescribed. A fraction of patients is resistant to clopidogrel resulting in decreased platelet inhibition despite adequate use. This finding is often termed high on-treatment platelet reactivity (HPR) and may lead to decreased patency in lower extremity arterial endovascular interventions. Current literature on HPR with lower extremity arterial endovascular interventions is limited to only a few studies. Resistance to clopidogrel is largely a result of CYP2C19 enzyme loss of function alleles. Several tests are available to measure clopidogrel resistance but light transmittance aggregometry remains the gold standard, yet direct genetic testing may be more reliable. One-year patency rates following lower extremity arterial endovascular interventions in patients with clopidogrel resistance (HPR) range between 35%-83% whereas those with the proper response to clopidogrel range between 73%-100%. Patients with decreased CYP2C19 activity show a significant decrease in one-year patency of endovascular femoropopliteal interventions (35% vs. 73%; p=0.006). Among patients tested for platelet function after in-stent thrombosis, up to 53% are resistant to clopidogrel. Lack of robust data limits our ability to predict patency in lower extremity arterial interventions for patients with HPR, but there is little doubt that longer patency seems to favor non-HPR patients. Large population, prospective trials are needed to guide our practice.

The incidence and prevalence of end-stage renal disease continues to grow, even as treatments improve. The vascular steal phenomenon is an infrequent but often debilitating complication of dialysis access placement, and management can be difficult. A specific technique called distal revascularization-interval ligation, or the DRIL procedure, has been used with success in managing this problem. Anatomically, the site of the steal is bypassed, and the native vessel just distal to the steal site is ligated, making duplex sonography evaluation complex. An examination algorithm is presented, with illustrative examples, to assist the sonographer in evaluating dialysis access patients when they have had the DRIL procedure. The algorithm is based on breaking the study into more easily managed components: (1) duplex sonographic evaluation of arterial inflow and runoff as well as venous outflow, (2) duplex sonographic evaluation of the bypass graft, (3) duplex sonographic evaluation of the fistula/shunt, and (4) physiologic testing of flows to the hand and digits. Based on the knowledge of the pathophysiology of steal and the configuration of the DRIL reconstruction, a complete and accurate evaluation can be performed with confidence.

The use of a native arteriovenous fistula (AVF) for dialysis is associated with fewer overall complications, and preserving long-term patency is a priority. The purpose of this study is to compare the patency and number of secondary interventions required of AVF when aneurysms are repaired with interposition prosthetic grafting (IG) vs aneurysm plication (PC).Methods: Fourteen patients with symptomatic aneurysms (15) of upper extremity autologous AVFs were treated with PC (eight) and IG (seven) between July 2007 and November 2013 at a single institution. The indications for operation were cutaneous thinning, ulceration, bleeding, and difficulty in cannulation. Patient characteristics, type of repair, patencies, and number of secondary interventions were recorded and analyzed.Results: Fourteen consecutive patients (nine men) with mean age of 48 years, underwent 15 aneurysm repairs. Five patients (33%) had radiocephalic, nine (60%) brachiocephalic, and one (7%) brachiobasilic AVF with the mean follow-up of 9 months. Eight aneurysms (53%) underwent plication vs seven (47%) interposition grafts. The average diameter of the aneurysm was 2.6 cm (IG) and 2.8 cm (PC) (not significant). At 6 months of follow-up, the patency for PC was 62.5% vs 57.1% for the IG group (P > .4). One IG was excised due to infection and another was lost due to an unrelated death. Two patients in the PC group were converted to IG due to aneurysm extension. Overall, IG patients required eight times more procedures (five dialysis catheters and three endovascular interventions) vs 1 intervention for the PC group (P < .01).Conclusions: Preliminary results show that aneurysm PC extends the life of the native fistula and requires fewer interventions to maintain patency. When possible, this method should be considered as the repair procedure of choice for AVF aneurysms.