Treatment of pelvic arteriovenous malformations with ethylene vinyl alcohol copolymer (Onyx).

In this article, two successful embolizations of large pelvic arteriovenous malformations (AVMs) with use of ethylene vinyl alcohol, a radiopaque, nonadhesive liquid casting agent, are reported. Both patients presented with large symptomatic pelvic AVMs requiring therapy. Coaxial microcatheter techniques were used to achieve complete success in one case and partial success in the other. Clinical success has been maintained in both patients at 2-year follow-up.

Intense inflammatory reaction to heparin polymer coated intravascular Palmaz stents in porcine arteries compared to uncoated Palmaz stents.

The objective of this study was to evaluate the efficacy of heparin-polymer-coated intravascular stents in the reduction of vessel stenosis. Three types of coatings for Palmaz stents were tested: 1) heparin covalently bound to a polyethylene oxide (Hp-PEO) tether; 2) heparin copolymerized with ethylene vinyl acetate (Hp-Elvax) and 3) Elvax alone. Polymer-coated stents and uncoated controls were deployed in the external iliac arteries following endothelial injury in 18 swine. The animals were maintained on an atherogenic diet and examined by angiography at 6 and 12 weeks. The stented segments were then harvested for histopathologic analysis. Both types of heparin-coated stents resulted in increased luminal narrowing as compared to the contralateral uncoated stents. At 6 weeks, average luminal stenosis was 48% for Hp-PEO stents vs 35% for uncoated stents (p <0.05). At 12 weeks, average luminal stenosis was 36% for Hp-PEO stents vs 26% for uncoated stents (p = NS). For Hp-Elvax stents, the average stenosis was 58% vs 33% for uncoated controls (p < 0.05) at 6 weeks and 47% vs 19% for uncoated controls (p <0.05) at 12 weeks. There was no significant difference between Hp-Elvax stents and Elvax stents (p = NS). Increased luminal narrowing in coated stents was primarily secondary to a marked inflammatory response. Heparin-polyethylene oxide and heparin-ethylene vinyl acetate-coated stents resulted in increased luminal narrowing as compared with uncoated stents, due to a marked inflammatory response.