Percutaneous autologous venous valve transplantation: Short-term feasibility study in an ovine model
Presented at the American Venous Forum meeting, San Diego, Calif, Feb 17, 2007.
Dusan Pavcnik, MD, PhD
, Qiang Yin, MD
, Barry Uchida, BS
, Won Kyu Park, MD
, Hanno Hoppe, MD
, Man Duck Kim, MD
, Frederick S. Keller, MD
, Josef Rösch, MD
Oregon Health and Science University, Dotter Interventional Institute, Portland, Ore.
Limited experience with bioprosthetic venous valve percutaneously inserted into femoral veins in 15 patients has been promising in short-term results only to show disappointing long-term results. Percutaneous autogenous venous valve (PAVV) transplantation was explored in an ovine model as a possible alternative treatment.
PAVV consisted of a vein segment containing a valve that was attached to a stent template. The stent templates (n = 9) were designed and hand made in our research laboratory. They consist of two stainless steel square stents 13 or 15 mm in diameter to fit the ovine jugular veins (JV), which ranges from 10 to 15 mm in diameter. A valve-containing segment of JV was harvested and attached with sutures and barbs inside the stent template (n = 9). The valve devices were then manually folded and front loaded inside the 4 cm chamber of the 13F delivery sheath and delivered into the contralateral JV by femoral vein approach. Transplanted PAVVs were studied by immediate and 3 months venograms. Animals were euthanized at 3 months, and jugular veins harvested to perform angioscopic evaluations in vitro.
PAVV transplantation was successful in all nine animals. Good valve function with no reflux was observed on immediate and 3 months venograms in eight valves. The transplanted maximal JV diameter ranged from 10.2 mm to 15.4 mm (mean 13.1 ± 1.5 mm). Venoscopic examination revealed intact, flexible, nonthickened valve leaflets in eight specimens. One PAVV exhibited normal function of one leaflet only; the other cusp was accidentally cut during the transplantation procedure. All transplanted autologous valves were free of thrombus and incorporated into the vein wall of the host vessel.
This study demonstrated that autogenous valve transplants remained patent and competent without long-term anticoagulation for up to 3 months. The percutaneous autogenous venous valve may provide in future minimally invasive treatment for patients with chronic deep venous insufficiency, but long-term studies need to be done to document its continued patency and function.
This report shows that leaflets lined with preserved endothelial cells prevented both neointima and intimal hyperplasia and enhanced and prolong the functionality of the autologous valves. A critical issue in using percutaneous autologous venous valve transplantation therapy and preventing thrombosis is the delivery of the transplanted valve leaflet with its endothelial cells still intact and fully functioning.
This was done in cow jugulars. All were successful. They remove a segment of vein with a valve and attach it to a steel stent, then implant it in the jugular. Because there is a layer of vein over the steel stent, it does not thrombose despite no anticoagulation for three months.
It's a long way from cows to humans, but this could be a viable technique for CCSVI patients in the future.