At the recent VEITHsymposium, W L Gore & Associates announced that the FDA has given the company clearance to market its GORE PROPATEN Vascular Graft for peripheral use, including lower-limb bypass and dialysis access surgery. The GORE PROPATEN Vascular Graft is specifically designed for those vascular procedures in which the risk of acute graft thrombotic failure is of clinical concern.
According to the research, the GORE PROPATEN Vascular Graft is the first ePTFE vascular graft that reduces thrombosis (European Journal of Vascular and Endovascular Surgery 2003;25(5):432-437) and is designed to address the clinical problem of thrombotic vascular graft failure. The GORE PROPATEN Vascular Graft is the first and only Expanded polytetrafluoroethylene (ePTFE)-heparin combination in an emerging class of medical products that combine mechanical and biological elements. It is designed to address the gap in clinical performance between synthetic and vein grafts by bonding the anticoagulant drug heparin to the surface of the graft using proprietary heparin end-point covalent bonding.
The GORE PROPATEN Vascular Graft harnesses the anticoagulant properties of heparin directly at the luminal surface of the graft. The proprietary end-point attachment mechanism serves to anchor heparin molecules to the luminal surface while still maintaining heparin’s intrinsic bioactive properties. According to the company, the result is a thrombo-resistant BioActive graft surface that retains its bioactive properties over time.
More than 10,000 GORE PROPATEN Vascular Grafts have been successfully implanted worldwide in four years of commercial availability overseas. In research, the graft has demonstrated favorable one-year primary patency rates (80%) [Italian Journal of Vascular & Endovascular Surgery 2006;13(3):137-147], when compared to autologous vein grafts (81%) and ePTFE synthetic grafts (66%) in the same application.
The GORE PROPATEN Vascular Graft has demonstrated improved thrombo-resistance and patency compared to standard ePTFE grafts in pre-clinical in vivo tests. The thrombo-resistant surface technology employed on the GORE PROPATEN Vascular Graft is designed to maintain bioactivity over an extended time period, thus increasing the potential for sustained performance improvement and increased patency.
According to Dr Marc Bosiers, Department of Vascular Surgery, AZ St Blasius Hospital, Dendermonde, Belgium, the use of the heparin-bonded ePTFE graft “…may represent a viable alternative for below-knee bypasses, which have traditionally yielded less than desirable outcomes.” His study, entitled; “Heparin-bonded expanded polytetrafluoroethylene vascular graft for femoropopliteal and femorocrural bypass grafting: 1-year results,” the heparin-bonded ePTFE graft provided ‘promising early patency and limb salvage results’. The study appears in the February 2006 issue of Journal of Vascular Surgery.
Several prosthetic materials have been used for femoropopliteal bypass grafting in patients with peripheral vascular disease in whom a venous bypass is not possible. ePTFE is the most commonly used, but patency results have not always equalled those achieved with vein, especially in below-knee reconstructions.
The study assessed the performance of a new heparin-bonded ePTFE vascular graft. From June 2002 to June 2003, 86 patients (62 men and 24 women; mean age, 70 years; 99 diseased limbs) were enrolled prospectively in a non-randomized, multi-center study of the heparin-bonded ePTFE graft. Fifty-five above-knee and 44 below-knee (including 21 femorocrural) procedures were performed. Follow-up evaluations consisted of clinical examinations, ultrasonographic studies, and distal pulse assessments. Patency and limb salvage rates were assessed by using life-table analyses.
All grafts were patent immediately after implantation. There were no graft infections or episodes of prolonged anastomotic bleeding. During the one-year follow-up, ten patients died, 15 grafts occluded, and five major amputations were performed. The overall primary and secondary one-year patency rates were 82% and 97%, respectively. The limb salvage rate in patients with critical limb ischemia (n = 41) was 87%. Primary patency rates according to bypass type were 84%, 81%, and 74% for above-knee femoropopliteal, below-knee femoropopliteal, and femorocrural bypasses, respectively; the corresponding secondary patency rates were 96%, 100%, and 100%.
In this study, the heparin-bonded ePTFE graft ‘provided promising early patency and limb salvage results’, with no device-related complications, in patients with occlusive vascular disease. Specifically, the researchers called for longer-term and randomized studies to determine whether the GORE PROPATEN Vascular Graft provides results superior to those achieved with other prostheses, especially in patients at increased risk of early graft failure, such as those undergoing below-knee bypass and those with poor run-off or advanced vascular disease.
In addition a second study, entitled, “Results with heparin bonded polytetrafluoroethylene grafts for femorodistal bypasses,” published in the August 2006 issue of the Journal of Cardiovascular Surgery (47:407-13) assessed whether the Carmeda BioActive Surface (CBAS), which employs covalent end-point linkage to retain heparin on the device surface, as it is used on the Propaten vascular graft successfully, prolonged patency.
From June 2002 to December 2005, 138 patients (97 men and 41 women; mean age: 73 years) received the CBAS-ePTFE graft for 153 infrainguinal bypass procedures. Seventy-five above-knee (AK) and 78 below knee (BK – including 37 femorocrural) procedures were performed. Follow-up evaluations consisted of clinical examinations, ultrasonographic studies, and distal pulse assessments. Patency and limb salvage rates were assessed by using life-table analyses.
The results showed that the overall primary and secondary two-year patency rates were 73.6% and 86%, respectively. Two-year primary patency rates according to bypass type were 76.2%, 72.6%, and 68.9% for AK femoropopliteal, BK femoropopliteal, and femorocrural bypasses, respectively; the corresponding secondary patency rates were 87.5%, 87.8%, and 79.4%. The two-year limb salvage rate in patients with critical limb ischemia (n=68) was 89.9%.
According to the researchers, the outcomes show that CBAS-ePTFE bypass grafts appear to give prolonged patency rates and indicate that the use of this graft may represent a viable alternative for BK bypasses, which have traditionally yielded less than desirable outcomes. Again, they called for a prospective, randomized trial is required to provide more definitive information about the graft’s patency and limb salvage performance.
The company said that the FDA clearance of the GORE PROPATEN Vascular Graft, allows the company to expand its portfolio of advanced medical solutions to offer a real alternative for below-knee surgery.
Date: Feb/2007
