Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Heart valve – Annular member for supporting artificial heart valve
Reexamination Certificate
1998-09-25
2001-03-13
Milano, Michael J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Heart valve
Annular member for supporting artificial heart valve
C623S002100
Reexamination Certificate
active
06200341
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a mechanical heart valve and method for manufacturing the same.
Mechanical heart valves are used to replace native valves which no longer function properly due to disease or other factors. Mechanical valves typically include an orifice having one or more occulders, which regulate blood flow. Also, mechanical valves typically include a stiffening ring that helps the valve assembly resist the compressive annular loads to which it is exposed when implanted. The stiffening ring can be made integral to the valve orifice or mechanically attached to the valve orifice.
When the stiffening ring is mechanically attached to the valve orifice, a coupling mechanism is required. One coupling mechanism includes a lock wire. For example, the family of Sulzer Carbomedics Prosthetic Heart Valves utilize a titanium lock wire positioned in grooves on the outer wall of the orifice and inner wall of the stiffening ring. A window in the stiffening ring allows insertion of the lock wire when the groove on the orifice is aligned with the groove on the stiffening ring.
Typically, the stiffening ring is incorporated with the sewing cuff. Therefore, in order to perform the mechanical attachment of orifice and ring, the cuff must be cut or otherwise partially disassembled to allow the lock wire to be passed through the window of the stiffening ring and into the aligned grooves. Once the lock wire is inserted, the cuff must be stitched closed again. This process of cutting and repairing the sewing cuff is time consuming. Further, this process leads to rejection of valve assemblies due to visual discrepancies caused by the cut/sew process.
Therefore, there is a need for a mechanical heart valve assembly and method for manufacturing, which reduces the manufacturing time and reduces the rejection of valve assemblies due to visual discrepancies.
SUMMARY OF THE INVENTION
The present invention is directed toward a mechanical heart valve assembly. The mechanical heart valve assembly includes a generally annular valve orifice. The outer surface of the valve orifice has a circumferential lock wire groove. A generally annular valve support ring surrounds at least a portion of the valve orifice. The support ring includes an inner surface with a circumferential lock wire groove. The orifice lock wire groove and support ring lock wire groove are positioned generally opposite each other. A lock wire is positioned in the grooves, operably coupling the orifice and support ring.
The lock wire comprises a super-elastic material. In one embodiment, the lock wire comprises nickel-titanium alloy, e.g., SE508 alloy. The lock wire includes a first and a second end and is generally “C” shaped. In one embodiment, the distance between the first and second ends of the lock wire is about 0.115 inches. In one embodiment, the lock wire has a cross-sectional diameter of about 0.0135 inches.
The support ring includes a window for receiving the wire. In one embodiment, a sewing cuff is disposed circumferentially about at least a portion of the support ring, covering the window.
Additionally, the present invention is directed toward a method of manufacturing a mechanical heart valve assembly. The mechanical heart valve assembly includes an orifice, a stiffening ring, and a lock wire. The lock wire is formed into a super-elastic “C” shape. The stiffening ring is aligned with the orifice so that the stiffening ring surrounds at least a portion of the orifice and so that a lock wire groove on an inner wall of the stiffening ring is generally aligned with a lock wire groove on an outer wall of the orifice. A first end of the lock wire is inserted through a window in the stiffening ring and into the generally aligned lock wire grooves until all of the lock wire is seated in the lock wire grooves.
In one embodiment, a sewing cuff is positioned circumferentially about at least a portion of the stiffening ring. The first end of the lock wire pierces the sewing cuff before it is inserted into the window of the support ring.
The present invention provides several advantages. First, there is no need to cut or otherwise disassemble the sewing cuff in order to insert the lock wire. Consequently, the number of manufacturing steps is reduced and the number of rejections based on visual discrepancies in the cuff is reduced. Both of these reductions help lower the manufacturing cost of the heart valve assembly. Additionally, the super-elastic lock wire is relatively easy to insert and returns to its memory shape when seated in the lock wire grooves. The lock wire will retain its pre-formed shape in a wide range of temperatures and after repeated sterilizations.
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Jones Melanie E.
Kelley Timothy A.
Barrow Kenneth S.
Lyren Phillip S.
Milano Michael J.
Scott Timothy L.
Stewart Alvin
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