WO1998017202A1

WO1998017202A1 - Method and apparatus for endovascular venous transplantation

Info

Publication number: WO1998017202A1
Application number: PCT/US1997/018736
Authority: WO
Inventors: Alan B. Lumsden; John D. Hughes
Original assignee: Emory University
Priority date: 1996-10-22
Filing date: 1997-10-21
Publication date: 1998-04-30
Also published as: AU4906497A

Abstract

The present invention provides a device (10) for endovascular deployment within a first blood vessel (2) comprising a preselected portion of a second blood vessel (4) having a predetermined length and diameter, and attached to at least a portion of an inner surface (6) of a radially self-expanding stent (8). The second blood vessel graft (4) can be any vessel of the body, but is preferably a vein or an artery. Sutures (12) can be used to attach the stent (8) to the second blood vessel (4).

Description

METHOD AND APPARATUS FOR ENDO VASCULAR VENOUS TRANSPLANTATION

FIELD OF THE INVENTION

The present invention relates to a device and method for endovascular

deployment of a fresh or cryopreserved venous graft at a predetermined site in a patient.

BACKGROUND OF THE INVENTION

Venous insufficiency is a widespread problem, affecting up to 20 million people

in the United States alone. (See, Taheri SA, Rigan D, Wels P, Mentzer R, Shores Rm.

Experimental prosthetic vein valve. Am J Surg 1988; 156-144.) The chronicity of the

disease leads to great expense in both physical morbidity and loss of work.

The problems of valvular insufficiency and outflow obstruction lead to a

common pathway of increased venous pressure, and subsequent limb edema, skin

changes, and eventual ulceration. Although current techniques are often effective and

produce initial healing, they leave the extremity subject to recurrence, and require

diligent maintenance.

Direct treatment of the primary problems include conventional surgical valve replacement or repair to restore valvular competency, and vein replacement to alleviate

outflow obstruction (See, Taheri SA, Lazar L, Elias S. Status of vein valve transplant

after 12 months. Arch Surg 1982; 117:1313-1317; Bry JD, Muto PA, O'Donnell TF,

Isaacson LA. The clinical and hemodynamic results after axillary-to-popliteal vein valve

transplantation. J Vase Surg 1995; 21 : 110-119; and Arch Surg 1967; 95:826-834).

These types of reconstruction require relatively extensive dissection and mobilization of

already diseased vessels, and, as such, the repaired vessel may be prone to thrombosis and dilatation with recurrent obstruction and incompetence, leading to recurrent venous

hypertension.

Two patents to Dardik et al., U. S. Patent No. 5,131,908 and U.S. Patent

4,990,131, both for a "Tubular Prosthesis for Vascular Reconstructive Surgery and

Process for Preparing Same" are directed to the use of chemically fixed (tanned)

umbilical cord vessels which are designed for conventional surgical implantation. The

chemically fixed vessel portions may be attached to an external mesh support which

allows for ingrowth of extra fibrocollagenous tissue from outside the graft at the surgical implantation site.

Likewise, U.S. Patent No. 5,500,014 to Quijano et al., for a "Biological Valvular

Prosthesis" is directed to the use of a chemically fixed biological derived conduit that

has at least one integrally formed tissue valve for conventional surgical implantation. A process of chemical fixation utilizing glutaraldehyde is used to chemically fix the valve so that it normally remains open and closes upon the exertion of back pressure. A support cage or external prosthesis can be added to strengthen the valve. Additionally,

DeLaria et al., "Hemodynamic evaluation of a bioprosthetic venous prosthesis", J. Vase

Surg. (United States) Oct. 1993, 18(4) p. 577-84 is directed to utilizing glutaraldehyde

fixed bovine jugular veins as a venous valve substitute for conventional surgical implantation.

These conventional valve transplants are prone to thrombosis and graft dilation,

with subsequent incompetence. Thus, there is a need in the art for a device and a

minimally invasive method of graft delivery which minimizes complications associated with conventional. Accordingly, the present invention provides a device and methods

for the construction and endovascular placement of a native fresh or cyro preserved

venous valve-stent graft in a vein as a potential new treatment of valvular incompetence.

Venous reflux is also a key factor in the widespread and often debilitating

disease of venous insufficiency. Valve transplantation has been successfully performed

to restore valve competency, but necessarily involves a relatively large operative

procedure for recovery of the donor valve segment and graft interposition to the

recipient vein. Accordingly there exists a need for a technique of valve transplantation

requiring minimally invasive methods of donor valve harvest, and valve deployment in the recipient vein. Accordingly, the present invention provides a fresh or cyro-preserved

section of donor vein mounted on a stent for endovascular deployment in a recipient vein.

SUMMARY OF THE INVENTION

The present invention provides a device and a method of endovascular delivery

and deployment of a self-expanding stent which surrounds a section of fresh or

cryopreserved venous tissue. An appropriately sized fresh or cyro preserved venous

graft is sutured in position within the lumen of a standard endovascular stent, e.g., a Wallstent (Schneider). Deployment is generally directed under fluoroscopic

visualization.

The endovascular venous graft of the present invention is believed to be

particularly useful in treating dialysis associated central venous stenosis or central

venous stasis. Therefore, the endovascular venous grafts of the invention may also contain one or more venous valves as directed by the patient's needs.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a photograph which shows, from top to bottom, an introducer and dilator for

deployment of the stent and attached venous graft. A scalpel is shown at bottom for

referencing size.

Figure 2 is a close up photograph of the stent of one embodiment of the invention containing the venous graft sutured within the lumen of the stent.

Figure 3 is a photograph showing at left the graft/stent preloaded on the introducer

catheter with dilator in position for deployment. A scalpel is shown at right for

referencing size.

Figure 4 is a side elevational drawing of the stent with a venous graft sutured in the

lumen.

Figure 5 is a cross-sectional view of the stent/graft deployed at within a patient's blood

vessel.

DETAILED DESCRIPTION OF THE INVENTION

As shown in Figures 4-5, the present invention provides a device 10 for

endovascular deployment within a first blood vessel 2 comprising: a preselected portion

of a second blood vessel 4 having a predetermined length and diameter and attached to

at least a portion of an inner surface 6 of a radially self-expanding stent 8. The second

blood vessel (graft vessel) can be any vessel of the body but is preferably a vein or an

artery.

In one embodiment the second blood vessel is a vein and the preselected portion contains at least one valve, however the venous graft need not contain a valve. In the

embodiment shown in Figures 4-5 the second blood vessel portion (graft) 4 is attached

to stent 8 by sutures 12. One of skill in the art will recognize that other means of

attachment are possible, including, for example, biocompatable cements such as fibrin

glue or collagen glue.

The preselected portion of the second blood vessel can be venous graft material that is harvested and deployed as fresh tissue. In one embodiment, the preselected

portion of the second blood vessel is cryopreserved tissue.

Figures 1-3 are actual color photographs of one embodiment of the device of the

invention as set forth and described in Figures 4-5. Figures 1-3 are not necessary for an

understanding of the invention and are presented merely for clarification of the

embodiments set forth and described herein..

The present invention also provides a method of treating a predetermined section

of a first blood vessel, comprising: placing, by endovascular means, a preselected

portion of a second blood vessel having a predetermined length and diameter and attached to at least a portion of an inner surface of a radially self-expanding stent within

the first blood vessel at the predetermined section. The predetermined section can be

any section of any vessel within the body. EXAMPLE 1

MATERIALS AND METHODS

In an ex vivo model, a segment of native vein containing a valve is placed inside

a self expanding stent, and deployed inside a vein from a remote access site. After

deployment, the valve is inspected angioscopically from both the downstream and

upstream ends, demonstrating valve patency and competence. Photographs of the

valve-stent construction and the deployment apparatus are presented as Figures 1-3.

A segment of external jugular vein containing a valve was exposed and mobilized

in a dog. The valve was examined for competence and patency using a strip test and

Doppler flow probe. The segment was excised and sewn inside a self-expanding

stainless steel stent, leaving only 1-2 mm of stent exposed on each end (Figs. 1-2). The

apparatus was then compressed and loaded into a #14F introducer (Fig. 1 and 3). The

valve stent was deployed by withdrawing the introducer over a #12F dilator, uncovering

the valve-stent (Fig. 3).

To test the device, it was deployed in transparent 3/8" plastic tubing. Patency

and competency of the device was determined by direct angioscopic examination of the

valve while injecting the tubing with saline both retrograde and antegrade. DESCRIPTION OF A PRESENTLY PREFERRED

EMBODIMENT OF THE DEVICE

Components:

1) 4 cm length of axillary vein, harvested from the patient's upper

arm, which contains a hemodynamically competent valve.

2) Wallstent (Schneider, Inc. U.S.A.), 10 mm diameter, 4 cm

length.

3) The vein is placed inside the self expanding Wallstent and sutured

in situ (Figs. 2 and 4).

4) The Wallstent is compressed and placed inside a 12Fr sheath (Fig. 3).

5) The self expanding stent opens spontaneously exposing the valve

to venous flow.

One of skill in the art will appreciate that the size of the graft, stent and deployment device as well as the type of stent can vary depending upon the particular area of the patient being treated and the pathological condition associated therewith.

Likewise, the stent can be constructed of any of a number of suitable materials all well

known in the art such as, e.g., stainless steel or a biocompatable polymer.

The venous graft tissue can be harvested fresh and utilized or a cryopreserved specimen can be utilized. Methods are known in the art for cryopreservation of blood

vessel tissue such as, for example, those utilized by CryoLife, Inc. of Atlanta, GA.

RESULTS

Patency and competency of the valve-stent were confirmed. No flaps or folds

were observed after 1 week of implantation. The valve leaflets functioned in a normal

fashion with both retrograde and antegrade injection. The methods and devices

demonstrate herein maintenance of patency and competency and offer encouraging new

minimally invasive methods of therapy.

EXAMPLE 2

METHODS AND MATERIALS

Five female goats were studied. A valve-stent (V-S) was constructed in the following method: A valve-containing segment of external jugular vein was excised

using an endoscopic subcutaneous video-assisted technique; the segment was sutured

inside a self-expanding stainless steel stent Wallstent, covering all but the terminal 1-2

mm of each end of the stent. The V-S was compressed and loaded into a 14 Fr

introducer sheath which was then inserted retrograde into the contralateral external

jugular vein through a small cutdown and venotomy. The V-S was deployed by

withdrawing the sheath over a 12 Fr dilator, leaving the expanded stent in place. The

goat was given 100 u/kg heparin SQ every 12 hours. At one week, patency and competency was evaluated with a flow probe, in situ retrograde and antegrade

endoscopy, and strip test. The V-S was excised and inspected histologically.

RESULTS

All five V-S were patent with competent valve function. A small non-occlusive

luminal clot was attached to the downstream exposed stent struts on two V-S.

Microscopic evaluation demonstrated no valve pathology.

CONCLUSION

In this goat model, we have demonstrated the feasibility of venous valve

transplantation, maintaining patency and competency, using minimally invasive

techniques of endovascular delivery and deployment. The techniques, methods and devices of the present invention are discussed further in recent publications, e.g., in "endoscopic Venous Valve transplantation with a

Valve-Stent Device", Ofenloch J.C. et al, Ann Vase Surg 1997; 11;62-67, and Chapter

32 (entitled "Valve Stent: A Technique for Endovascular Delivery of Functioning

Venous Valves") from the text "Current Critical Problems in Vascular Surgery" Volume

8, edited by Frank J. Veitch M. D. and published by Quality Medical Publishing, St. Louis Missouri (Critical Problems in Vascular Surgery 1997; 32:206-209 (in press)).

Throughout this application various publications and methods are referenced.

The disclosures of these publications and the referenced methods in their entireties are

hereby incorporated by reference into this application in order to more fully describe the

state of the art to which the invention pertains.

Claims

What is claimed is:

1. A device for endovascular deployment within a first blood vessel comprising a preselected portion of a second blood vessel having a predetermined length and

diameter and attached to at least a portion of an inner surface of a radially self- expanding stent.

2. The device of claim 1, wherein the second blood vessel is an artery.

3. The device of claim 1, wherein the second blood vessel is a vein.

4. The device of claim 3, wherein the second blood vessel is a vein and the

preselected portion contains at least one valve.

5. The device of claim 1, wherein the preselected portion of the second blood

vessel is attached to the stent by at least one suture.

6. The device of claim 1, wherein the preselected portion of the second blood is attached to the stent by a biocompatable cement.

7. The device of claim 6, wherein the biocompatable cement is selected from the

group consisting of fibrin glue and collagen glue.

8. The device of claim 1, wherein the preselected portion of the second blood

vessel is a venous graft material that is harvested and deployed as fresh tissue.

9. The device of claim 1, wherein the preselected portion of the second blood

vessel is a cryopreserved tissue.

10. The device of claim 1, wherein the stent is a hollow tubular stent and comprised

of a biocompatable material selected from the group consisting of a metal, a polymer, a

plastic or combinations thereof.

11. A method of treating a predetermined section of a first blood vessel, comprising:

placing, by endovascular means, a preselected portion of a second blood vessel having a predetermined length and diameter and attached to at least a portion of an inner

surface of a radially self-expanding stent within the first blood vessel at the

predetermined section.

12. The method of claim 10, wherein the predetermined section within the first blood

vessel is a diseased section of a patient's vein.