bioprosthetic valves

A forum to discuss Chronic Cerebrospinal Venous Insufficiency and its relationship to Multiple Sclerosis.

bioprosthetic valves

Postby Cece » Thu Mar 08, 2012 4:38 pm

http://www.sirmeeting.org/index.cfm?do= ... Index=9132
Syllabus Contributions for Distinguished Abstract: Improved Bioprosthetic Valve for the Treatment of Chronic Deep Venous Insufficiency Using an Autologous Endothelial Layer by Dusan Pavcnik

1. Purpose
Percutaneous transcatheter implantation of porcine small intestine submucosa (SIS) bioprosthetic valves has been reported as a treatment for chronic deep venous insufficiency. Endothelial progenitor outgrowths cells (EOCs), isolated from whole ovine blood, were evaluated as a source of in vitro autologous seeding for SIS endothelialization. Retention of the EOC monolayer was evaluated to test the feasibility of delivering an endotheliolized SIS valve.2. Objectives At the conclusion of this session, the attendee will be able to (minimum of 3):1. To be familiar with recent studies showing that leaflets pre-seeded with mature endothelial cells (ECs) prevented thrombus and IH from forming on the leaflets and enhanced valve functionality.
2. To have general notions that endothelial progenitor cells (EPCs) are being used as a source of autologous ECs, due to their ease of isolation from circulating blood.
3. To know the criteria for testing the retention of the endothelial layer through loading and delivery, in vitro and ex vivo flow.
3. Topic OutlineA percutaneously implantable bioprosthetic venous valve that remains functional over time is an attractive alternative to direct valvular reconstruction or transplantation. Animal studies demonstrated that leaflets lined with endothelial cells prevented IH, thereby prolonging valve functionality. Critical issues in using percutaneous valve therapy are the source of endothelial cells for harvest in patients and the ability to deliver the valve leaflet with its endothelium intact and fully functioning.
4. ReferencesPavcnik D Percutaneous Management of Deep Venous Reflux: Review of experimental work and clinical experience with bioprosthetic valve. JVM 2008; 13:75
Teebken OE Tissue-engineered bioprosthetic venous valve: Study in sheep. Eur J VES 2003; 25: 305
Pavcnik D Percutaneous Autologous Venous Valve Transplantation: Feasibility Study in an ovine model. JVS 2007; 46: 338
Hinds, M Potential of baboon endothelial progenitor cells for tissue engineered endografts. Biomed Mater Res 2008; 86: 804
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This is not for CCSVI, but for valves in chronic venous insufficiency of the legs. It sounds like they are transplanting valves made from porcine small intestines, making some sort of bioprosthetic valve? What caught my eye also is that they are also harvesting endothelial cells and then lining the valve with endothelial cells and this is preventing intimal hyperplasia.

Could a CCSVI stent be lined with endothelial cells, or would they be damaged when the stent is implanted?

This is for the future!
Cece
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Re: bioprosthetic valves

Postby Cece » Mon Jun 11, 2012 3:03 pm

http://www.jvascsurg.org/article/S0741-5214(07)00749-5/abstract
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.

Background

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.

Methods

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.

Results

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.

Conclusion

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.

Clinical Relevance

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.
Cece
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Posts: 8956
Joined: Mon Jan 04, 2010 4:00 pm


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