Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Including valve
Reexamination Certificate
2002-07-09
2004-02-03
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Including valve
C623S002180
Reexamination Certificate
active
06685739
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of implantable prostheses. More specifically, the present invention relates to implantable prosthetic cardiac, aortic, and venous valves.
BACKGROUND OF THE INVENTION
In human pathology, the proper functioning of both cardiac and venous valves is of paramount importance. Disorders of cardiac valves cause significant morbidity and mortality. These disorders affect persons of all ages and can result from congenital or degenerative conditions, as well as from the sequelae of infections. Stenosis and insufficiency of the aortic or mitral valves have a greater incidence than stenosis and insufficiency of the tricuspid and pulmonary valves. Venous insufficiency is believed to contribute to various maladies, including edema, varicose veins, aching leg pain while standing, lipodermatosclerosis, and ulcerations. Venous insufficiency is essentially caused by venous hypertension and chronic venous stasis due to valvular incompetence both of an idiopathic nature and of a secondary nature following past illnesses of the venous systems.
A prosthetic cardiac or venous valve may regulate the direction of the pulsating blood flow so as to limit the occurrence of blood stasis in the region about the valve. By maintaining the direction of blood flow therethrough, a prosthetic cardia, aortic, or venous valve may alleviate the maladies resulting from valve disorders or venous insufficiency. A prosthetic valve should therefore permit blood flow in the proper predetermined direction to limit or prevent backflow of the blood in a reverse direction.
The art has seen several attempts for providing a prosthetic valve to alleviate the consequences of cardiac valve disorders and of venous insufficiency. These attempts generally fall into two categories, biologic valves and mechanical valves. Biologic valves are comprised of a stent supporting a number of circumferential leaflets made of a flexible material. If the material is biologic in nature, it may be either a xenograft, that is, harvested from a non-human cadaver, or an allograft, that is, harvested from a human cadaver. For example, it is known in the art to apply a pericardium biological tissue layer covering, for providing the valve leaflets, to a stent which provides structural annular integrity to the prosthesis. Non-biologic material such as polyurethane has also been used. The second category of prosthetic valves, mechanical valves, usually comprise a rigid annulus supporting up to three rigid leaflets. The annulus and leaflets are frequently formed in pyrolitic carbon, a particularly hard and wear resistant form of carbon. The annulus is captured within a sewing ring so that the valve may be attached to tissue at the location of the replaced valve. Unfortunately, surgically positioning these implants typically requires suturing or sewing the device into the blood vessel, increasing the risk of thrombosis due to the resulting suturing or anastomoses of the body vessel.
These attempts typically provide a valve structure having a relatively rigid tubular body structure which supports a flexible valve leaf structure. That is, any structural rigidity imparted to the tubular body structure is separated from the valve leaf structure. For example, U.S. Pat. No. 4,759,759 discloses a prosthetic valve having a solid stent member having a diametrically-opposed upstanding posts and a substantially cylindrical flexible cover. The two portions of the cover extending between the upstanding stent posts may be collapsed against each other in sealing registry over a fluid passageway defined by the stent. The stent, being a solid member, limits the radial collapsing thereof for endoscopic delivery within a body lumen. The cover, being unsupported by the stent within the fluid passageway of the valve, must itself provide sufficient strength and resiliency to optimally regulate fluid flow. Alternatively, U.S. Pat. No. 5,855,691 discloses a prosthetic valve having a radially expandable covered stent which defines an elongate fluid passageway therethrough. A flexible valve is disposed within the fluid passageway to regulate fluid flow therethrough. The valve is formed of a flexible and compressible material formed into a disc with at least three radial incisions to form deflectable leaflets. While the stent circumferentially supports the valve body, the leaflets are not supported by any other structure within the fluid passageway. There is therefore a need in the art for a unitary prosthetic valve construction which provides structural reinforcement to both the tubular body portion of the valve and to the valve leafs supported thereon.
SUMMARY OF THE INVENTION
The present invention is directed to providing a fully prosthetic valve having valve leafs formed from a covered valve leaf frame and which may be implanted using a minimally-invasive, endoscopic technique.
The present invention provides a prosthetic valve for implantation within a body lumen. The prosthetic valve of the present invention provides a device for regulating and maintaining the direction of a pulsating fluid flow through the body lumen. The valve includes a radially-collapsible scaffold portion and a radially-collapsible leaf valve portion. The scaffold portion includes a tubular open body scaffold defining a fluid passageway therethrough. The leaf valve portion is deflectable between a closed configuration in which fluid flow through the valve passageway is restricted and an open configuration in which fluid flow through the valve passageway is permitted.
Each of the valve leafs desirably includes a valve leaf frame having an open construction so as to facilitate radially-collapsing or -expanding the leaf valve portion of the valve. Each valve leaf frame defines a valve leaf aperture with the scaffold. The present invention seals each valve leaf aperture to prevent fluid flow therethrough. The material used to seal each valve leaf aperture is sufficiently thin and pliable so as to permit radially-collapsing the leaf valve portion for delivery by catheter to a location within a body lumen. A fluid-impermeable biocompatible non-thrombogenic valve leaf cover may be positioned on each valve leaf frame so as to seal the valve leaf aperture. The valve leaf cover may be formed from a surgically-useful textile such as Dacron, polyethlylene (PE), polyethylene terephthalate (PET), silk, Rayon, or the like. The valve leaf cover may also be formed of a surgically-useful polymeric material such as urethane, polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE). The valve leaf cover may also coated with a cellular growth-inhibiting drug such as Heparin or Taxol or another such composition.
Similarly, each of the valve leaf apertures may be covered with cultured tissue cells derived from a either a donor or the host patient which are attached to the valve leaf frames. The cultured tissue cells may be initially positioned to extend either partially or fully into each valve leaf aperture. In order to provide additional support to the attached cultured tissue cells, a microfilter-type support mesh spanning the valve leaf aperture may also be provided. The present invention further contemplates that the supporting scaffold and valve leaf frames may be formed of either a bioabsorbable material or a non-bioabsorbable material. It is contemplated that the scaffold and valve leaf frames which are formed from a bioabsorbable material will eventually be displaced by the tissue cells as the tissue cells mature. Eventually the cells alone will provide the fully functioning valve. Alternatively, when the scaffold and valve leaf frames are formed from a non-bioabsorbable material, the cultured cells provide a means for reducing any undesirable biological response by the host.
The leaf valve member is normally spring biased towards the closed configuration. The present invention also contemplates biasing the leaf valve member towards the open configuration to simulate known anatomical mechanics of a valve in which the leaf valve portion wo
DiMatteo Kristian
Marshall Peter
Hoffman & Baron LLP
Jackson Suzette J.
Sci-Med Life Systems, Inc.
Willse David H.
LandOfFree
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