Ovine Graft (Omniflow II) Versus PTFE in Below Knee Arterial Reconstruction

The study intends to compare commonly used PTFE grafts with the biologic ovine graft Ominiflow II for below-knee bypass surgery in patients with peripheral artery occlusive disease with no autologous vein graft available. The hypothesis of this randomized trial is that that Omniflow II does not have a higher patency than PTFE over 36 months (one-sided test). An interim analysis will be performed at 18

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 For various reasons most biological grafts have been withdrawn from the market and Omniflow II (Bio Nova International, Mel-bourne, Australia) is currently the only biological vascular prosthesis available for peripheral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

All patients between the ages 20 to 90 with peripheral arterial disease with severe, life-style limiting claudication, rest pain or tissue lesions based on occlusion of the femoral or popliteal artery can be considered, if no suitable vein is available for the reconstruction in infrapopliteal reconstructions. Written consent is obtained from all volunteering patients including willingness to participate in the follow-up process. Primary end point of the study is primary patency, defined by duplex scan as freedom from binary restenosis of 50%.

Eligibility Criteria:
Inclusion Criteria:

* Age between 20 to 90
* Peripheral arterial occlusive disease with life-style limitation, claudication, rest pain, tissue loss,
* No suitable vein for reconstruction available
* Written consent obtained

Exclusion Criteria

* Acute limb threatening ischaemia
* Patient younger than 20
* Pregnant women
* Myocardial infarction during past 30 days
* Stroke
* Life expectancy \< 1 year