US 5,207,706 AGrant
Method and Means for Gold-Coating Implantable Intravascular Devices
Issue Date:1993-05-04
•7 Claims
•2 Drawing Sheets
Abstract
Implantable vascular prostheses, formed of synthetic, woven fibers are coated with a thin layer of metallic gold sufficient to create a continuous coating over the surfaces of the fibers that come into contact with blood. The coating is applied by vapor deposition or sputtering to coat the fibers without blocking or bridging the interstices formed by the intersection of the fibers.
Metadata
Inventor
- Gerald Menaker, M.D.
Application Information
Application Number:US 6409121
Filing Date:1991-01-07
Priority Date:1988-10-05
Art Unit:338
Classifications
IPC:
A61F 206
Field of Search:
6234276041;11;12;662266
Patent Drawings (2 sheets)
Description
Brief Summary of the Invention
Vascular grafts, shunts, patches and heart valves are provided with a metallic coating which is chemically inert, readily deformable, hydrophobic, electrically conductive and non-reactive with body tissue or fluids.
In a first, preferred embodiment of the present invention, synthetic vascular shunts and patches are provided with gold coatings applied by vapor-deposition or by sputtering. The use of the vapor-deposition technique is described in U.S. Pat. No. 4,167,045 (Sawyer) and in articles entitled "Vacuum Metallized Shielding" (distributed by Deep-Coat Metallizing, Inc. of Lemont, Illinois), and R. Allen Myers. "An Introduction to Functional Thin Films" presented at the June, 1987 EMI/RFI Symposium of Plastics Engineers. Sputtering is described in "The Handbook of Thin Film Technology" edited by Leon Maissel and Rheinhardt Glang (McGraw-Hill Publishing Co., 1970) at pages 3-30 through 3-37.
Such a coating should be capable of flexing with the implant as the implant is twisted into position for permanent attachment, as the implant may flex during pulsative transmission of blood therethrough. Such coating should also preserve the porous construction of the graft to allow for the infiltration of fibrous tissue.
In yet another preferred embodiment of the invention, artificial heart valves and the suturing cuffs used to anchor such valves are similarly coated with gold prior to implantation.
These and further aspects of the present invention will be more apparent upon a consideration of the accompanying drawings wherein:
FIG. 1 is a sectional view of a portion of an implant in the form of a vascular shunt or graft embodying the present invention;
FIG. 2 is an implantable patch embodying the present invention;
FIG. 3 is a scanning electron microscope photograph taken at 15 KU #20.times. magnification showing vapor-deposition coating of a Dacron (Registered U.S. Trademark) implant;
FIG. 4 shows the shunt of FIG. 3 at 15 KU 86.times. magnification; and
FIG. 5 shows a heart valve and suture cuff generally of the type discussed herein.
Detailed Description of the Invention
It is well-known that gold may be applied to a substrate or an article by the techniques of vapor-deposition or sputtering.
The present invention involves the construction of implantable, grafts, shunts, patches, heart valves or other devices to be incorporated as part of the vascular system of a living body consistent with the foregoing teachings of the prior art and providing the finished implants with a coating of gold. The coating is applied to the surfaces of the implant intended to come into contact with the patient's blood stream thereby providing a lining or coating which is chemically inert and which has been observed and predicted to inhibit the formation of thromboses and possibly infection.
A preferred embodiment of the present invention involves the manufacture of synthetic vascular grafts, shunts and cuffs from products such as Dacron (Registered U.S. Trademark), Teflon (Registered U.S. Trademark) or Gore-Tex (Registered U.S. Trademark) materials, and the subsequent application of a layer of gold thereto. It is expected that the layer of gold may be applied either during or after the manufacturing process, depending upon the specific manufacturing steps undertaken by the producer of such implants. For example, for implants formed by "rolling" a cylinder from a flat piece of synthetic material, it is expected that gold may be applied to the material before or after such rolling occurs. Where material is drawn, as over a mandrel, to form a seamless tube, it is expected that the vapor deposition or sputtering techniques will induce the gold to adhere tightly to the inner and outer walls of the implant.
In a first, preferred embodiment, a vascular shunt manufactured by Meadox Medicals, Inc. of Oakland, N.J. 07436 from Dacron (Registered U.S. Trademark) and sold under the trademark "Cooley 2" is coated with gold by the vapor-deposition process. As seen in FIG. 1, graft construction 10 includes a length of cylindrical shunt or graft 11 to which gold has been applied to outer wall 12 and inner wall 13 and the Dacron (Registered U.S. Trademark) construction is characterized by numerous interstices created by the woven nature of the fabric, as seen in FIGS. 3 and 4. It has been found desirable to maintain the openness of these interstices to provide sites for infiltration by fibrous body tissue. Such infiltration stabilizes and firmly holds the graft 11 after implantation. As shown in FIGS. 3 and 4, photomicrographic examination establishes that the individual fibers making up shunt 11 are coated evenly with gold without bridging or otherwise blocking the interstices formed by the weave pattern. It is expected that the gold so applied will penetrate within the intersticial fiber bundles so that the coating will extend inward from both the inner and outer surfaces.
The variety of vascular grafts manufactured by W. L. Gore and Associates use a fabric identified by the registered trademark Gore-Tex. The essential characteristic of Gore-Tex (Registered U.S. Trademark) fabric is a controllable and selectable distribution of pore sizes, making the material readily adaptable to create the type of pore distribution which will allow the implant to attract and support the growth of body tissue to hold the implant in place.
Another method of manufacture for graft 10 may be to vapor-deposit gold on an outer surface 14 of graft 11, then to turn graft 11 inside out to position gold layer 12 within shunt 11 along the path of blood flow.
Referring now to FIG. 2, the numeral 20 indicates generally a patch 21 prepared in accordance with the teachings of the present invention. A layer 22 of gold is applied to be coextensive with patch 21, and the patch may be trimmed to meet selected surgical requirements.
In the practice of a first, preferred embodiment of the invention, patch 20 has a coating 22 applied by vapor-deposition of metallic gold as described hereinabove.
Preferably, the use of gold with synthetic implants is contemplated. However, it is also expected that the techniques described herein are applicable to shunts such as those described in Dardik, et al. (U.S. Pat. Nos. 3,974,526 and 3,988,782).
Referring now to FIG. 5, the numeral 30 indicates generally an artificial implantable heart valve. The particular valve herein depicted is one manufactured and sold under the registered trademark "St. Jude Medical", and consists of a generally circular valve housing 31 within which valve leaflets 32 and 33 are pivotally mounted. Leaflet 32 is supported at pivot points 34 and 35, while leaflet 33 is supported at pivot points 36 and 37. Leaflets 32 and 33 are shaped and suspended in such fashion as to pivot open when blood is pumped or drawn there through, and to pivot shut, preventing backflow, between heart beats.
When implanted, valve housing 31 is surrounded by suture cuff 38 formed, in one embodiment, from bio-compatible Dacron.RTM. double velour vascular graft material. Cuff 38 is fashioned to eliminate seams along its outer surface to reduce the availability of sites for the generation of thromboses.
In the preferred practice of the present invention, valve 30 and cuff 38 are coated with gold by vacuum-deposition. Coating valve 30 provides the benefits described above with respect to prevention of thromboses, limiting of electrical currents, inertness and bio-compatibility. Gold coatings also help keep leaflets 32 and 33, and pivot points 34, 35, 36 and 37 clear of tissue and detritus to assure the reliable operation of the valve. It is also expected that the bacteriacidal properties of gold will aid in preventing or alleviating bacterial infections at the implant site.
Coating suture cuff 38 with gold provides these same benefits and preserves the presence of open interstices for the infiltration of fibrous tissue that will eventually anchor the cuff 30 and valve housing 31 into permanent contact with the heart tissue.
The use of the terms "vacuum deposition" or "sputtering" are not intended to be limiting, but to include other application techniques which allow devices such as those described herein to be protected by a coating of metallic gold while meeting the requirements of the present invention.
The present invention has been described in terms consistent with the implantation of artificial grafts, shunts, patches and valves in human beings, but it should be understood that the present invention may also be used in other animals as well.
While the foregoing has presented certain specific embodiments of the present invention, it is to be understood that these embodiments have been presented by way of example only. It is expected that others skilled in the art will perceive variations which, while differing from the foregoing, do not depart from the spirit and scope of the invention as herein described and claimed and no limitation as to the description of the present invention is hereby made or intended.
Claims
What is claimed is:
1. In a vascular graft for implanting into the blood circulatory system of a living recipient, said graft formed from a woven fabric of `synthetic` material polymeric substrate, said fabric characterized by interstices created by the woven nature of the fabric another, said graft having a surface formed by said fabric, said surface for exposure to the blood of said recipient, the improvement comprising: a thin layer of metallic gold applied to coat said fabric forming said surface, said layer applied to leave said interstices open and unblocked.
2. The construction of claim 1 wherein said vascular graft further comprises a tubular body formed from said fabric, said tubular body having an inner wall, said inner wall coated with gold.
3. The construction of claim 1 wherein said layer of metallic gold is vapor-deposited onto said vascular graft.
4. The construction of claim 1 wherein said layer of metallic gold i sputtered onto said vascular graft.
5. The construction of claim 1 wherein said synthetic material is tetrafluoroethylene polymer.
6. The construction of claim 1 wherein said synthetic material is polyethylene glycol terephthalate.
7. The construction of claim 1 wherein said synthetic material is expanded microporous polytetrafluoroethylene.
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