Ovine Graft (Omniflow II) Versus PTFE in Below Knee Arterial Reconstruction: A Prospective Randomized Multi Centre Study

Background

Despite advances in endovascular therapies, arterial bypass to restore blood flow to a patent distal artery often is the best option in the management of lower extremity occlusive arterial disease. The greater saphenous vein is the conduit of choice for infrainguinal reconstructions - but it is not always available or is otherwise unusable in a significant percentage of patients. In those situations, arterial reconstruction using prosthetic material is an option. Synthetic and biological vascular grafts have been used for some three decades. With time, synthetic conduits tend to increase their thrombogenic potential rather than diminish it by formation of neointima. Over time biological grafts have become alternatives to synthetic materials, mainly in the more demanding applications below the knee. For various reasons most biological grafts have been withdrawn from the market and Omniflow II (Bio Nova International, Mel-bourne, Australia) is currently the only biological vascular prosthesis available for peripheral revascularisation.

Objective

The Omniflow II prosthesis is a biosynthetic device formed from stabilised sheep collagen with an integral polyester mesh. It is produced by inserting polyester mesh-covered mandrels beneath the cutaneous trunci muscle of adult sheep for a period of 12-14 weeks. The collagen-encapsulated tubes are harvested and stabilised using glutaraldehyde. The design provides long-term structural stability of the prosthesis and compliance that is similar to that of an autologous artery. There are no randomised studies comparing the Omniflow II graft to either autologous vein or PTFE. Extensive in vivo testing has been performed for safety and efficacy. The Omniflow graft is registered in Europe, Australia, Canada and in a range of countries in South America and South East Asia.

Methods