This patent application is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "It is well known in the field of heart valve repair to use implantable annuloplasty rings for surgical correction of certain mitral or tricuspid heart valve disorders. Clinical experience has shown that the repair of heart valves, where this technique is possible, produces significantly better long term results than do valve replacements.
"Wright, U.S. Pat. No. 5,674,279, the contents of which are expressly incorporated by reference herein, describes in detail various effects of valvular dysfunction, known corrective procedures and various prosthesis that have been used in conjunction with mitral or tricuspid valve repair. Wright is also directed to an annuloplasty ring structure that has experienced considerable success in both mitral and tricuspid valve repair.
"Known annuloplasty rings are either completely flexible or have an internal frame in at least a portion of the annuloplasty ring to impart some structural rigidity. Those annuloplasty rings with a rigid internal frame (i.e., a frame is rigid both along a circumferential axis of the frame and radially relative to the circumferential axis) can interfere with normal movement of the mitral valve annulus during diastole and systole. More particularly, during diastole the mitral valve annulus assumes a substantially planar configuration. During systole the anterior leaflet of the mitral valve bows into the left atrium due to aortic pressure, forming the mitral valve annulus into a partially flattened saddle shape. A rigid annuloplasty ring can interfere with the anterior segment of the mitral valve annulus assuming this bowed configuration during systole, leading to a condition known as systolic anterior motion or SAM. Thus, this is one limitation of the Carpentier-Edwards D-Shaped 'Classic' semi-closed ring discussed in the Wright '279 patent, and the Carpentier-Edwards 'Physio' ring.
"Other rings are flexible, such as the Cosgrove-Edwards band, which is a fully flexible C-shaped ring and the Medtronic Duran ring, which is fully flexible and circular. Both of these rings are also discussed in the Wright '279 patent. Because flexible annuloplasty rings can be hard for surgeons to manipulate and implant due to their flexible nature, flexible rings and bands typically require a holder for implantation by a surgeon. Moreover, flexible rings are subject to axial compression or bunching when implantation sutures are tightened and tied during implantation.
"The present invention is directed toward overcoming one or more of the problems discussed above."
In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventor's summary information for this patent application: "A first aspect of the embodiments is an annuloplasty ring comprising an elongate
"tube of suturable material formed into a ring. A stiffener configured to prevent axial compression and to resist radial deformation of the ring is received in the formed tube in a first circumferential segment of the ring. As used herein, 'axial compression' means along a circumferential axis of the ring and 'radial deformation' means deformation radially (or transverse) of the circumferential axis. Thus, 'radial deformation' includes deformation in the same or opposite direction of blood flow with the annuloplasty ring implanted on a heart valve annulus. As used herein, 'resist radial deformation' means providing sufficient radial rigidity to prevent radial deformation of greater than 0.3 inches with a load of 25-75 grams (depending on the ring or band size, which for the embodiments described herein generally vary between about 40-24 mm across the trigones) applied across a major diameter, but to permit a substantially normal range of axial movement of a posterior portion of a mitral valve annulus with the annuloplasty ring installed on a mitral valve annulus and depicted in FIG. 7. In other words, with the first circumferential segment of the ring attached to the posterior portion of the mitral valve annulus between the right and left trigones. The qualifier 'substantially' means the qualified function or property occurs without material interference diminishing its intended effectiveness. An axial support configured to prevent axial compression of the ring and to permit substantially free radial deformation of the ring is received in the tube in a second circumferential segment of the ring. As used herein, 'substantially free radial deformation' means sufficient radial rigidity to prevent radial deformation of greater than 0.3 inches with a load of 25-75 grams (depending on the ring diameter) applied across the major diameter, but to permit a substantially normal range of axial movement of an anterior portion of a mitral valve aunulus with an annuloplasty ring installed with the second circumferential segment of the ring attached to an anterior portion of a mitral valve annulus, as depicted in FIG. 7. In one embodiment a close-coiled spring formed into a ring corresponding to the ring of suturable material is received inside the tube. In this embodiment the stiffener comprises a metal wire axially received in a cavity defined by the circumferential portion of the close-coiled spring corresponding to the first circumferential segment. In this embodiment the axial support comprises a circumferential portion of the close-coiled, spring corresponding to the second circumferential segment not having a metal wire axially received therein. The first circumferential segment of the ring may correspond to a posterior portion of a mitral valve annulus with the first circumferential portion configured to extend between the right and the left fibrous trigones of the mitral valve annulus upon implantation. The second circumferential segment of the ring may correspond to an anterior portion of a mitral valve annulus and the second circumferential segment is configured to extend between the right and left fibrous trigones of the mitral valve annulus upon implantation. The suturable material may be a braided heat settable material. The heat settable material may be polyethertetraphylate heat set into the desired cross-sectional configuration.
"Another aspect is a method of making an annuloplasty ring. The method includes providing a length of a close-coiled spring. A pre-formed stiffener is inserted into a cavity formed by the spring coils and axial movement of the stiffener within the cavity is prevented. The close-coiled spring is formed into a ring by securing the ends of the length of close-coiled spring together. A ribbon of suturable material is provided and formed into a ring by securing its ends together. The close-coiled spring formed into a ring is placed into contact with the ring of suturable material and the ring of suturable material is formed into a ring surrounding the close-coiled spring. The method may further include securing the close-coiled spring to the tube to prevent circumferential movement of the close-coiled spring within the tube. The method may further include inserting the close-coiled spring within an elastomeric tube. An elastomeric core may be inserted into the cavity formed by the spring coils with the elastomeric core having a length sufficient such that, with the spring formed in the ring, the elastomeric core prevents axial movement of the stiffener within the cavity.
"Yet another aspect is an annuloplasty ring band comprising an elongate tube of suturable material. A stiffener configured to prevent axial compression and to resist radial deformation of the ring is formed into a C-shape and sized and shaped to conform to a posterior portion of a mitral valve annulus extending between left and right trigones of the mitral valve annulus. The stiffener may comprise a close-coiled spring and a metal wire axially received in a lengthwise cavity of the close-coiled spring. A cap of a circular cross section with a chamfered edge may be provided at each end of the softener with the caps being configured to prevent the stiffener ends from protruding through the suturable material. The metal wire may be made of a bio-compatible metal having a diameter in a range of 0.015 and 0.050 inches. The bio-compatible metal may be a Carpenter MP35N alloy.
"The semi-rigid annuloplasty ring in accordance with the present embodiments provides a circumferential segment for providing desired axial rigidity while resisting radial deformation and an axiaily rigid and radially flexible circumferential segment which is conformable to valve anatomy when such conformity is required. In the particular application of an annuloplasty ring for a mitral valve repair, an annuloplasty ring in accordance with the present embodiments provides a posterior portion which is axiaily rigid while resisting radial deformation attachable to the mitral valve annulus between the left and right fibrous trigones and an axially rigid but radially flexible anterior segment attachable to the anterior portion of the mitral valve. The flexible annular portion can accommodate bowing of the anterior annulus out of the normal plane of the annulus into the left atrium as a result of aortic pressure during systole of a normally beating heart. The axial stiffness of the anterior segment prevents bunching of the annuloplasty ring suturable material cover during implantation and subsequent implantation suture tying. The semi-rigid annuloplasty band provides many of the advantages of the semi-rigid annuloplasty ring and meets the needs of surgeons that prefer a band with no anterior segment to the ring having an axially rigid and radially flexible circumferential posterior segment.
BRIEF DESCRIPTION OF THE DRAWINGS
"FIG. 1 is a plan view of a semi-rigid annuloplasty ring;
"FIG. 2 is a plan view of the semi-rigid annuloplasty ring of FIG. 1 with portions cut away to reveal the internal construction;
"FIG. 3 is a cross-section taken along line A-A of FIG. 2;
"FIG. 4 is a cross-section taken along line B-B of FIG. 2;
"FIG. 5 is a cross-section taken along line C-C of FIG. 2;
"FIG. 6 is a plan view of a semi-rigid stiffener of the annuloplasty ring of FIG. 1 with the suturable cover removed and portions of the stiffener shown in lengthwise cross-section;
"FIG. 7 is an isometric view of a semi-rigid annuloplasty ring of FIG. 1 sewn into the mitral aunulus of a heart during ventricular systole;
"FIG. 8 is a plan view of a semi-rigid annuloplasty band;
"FIG. 9 is a plan view of the semi-rigid annuloplasty band of FIG. 8 with portions cut away to reveal the internal construction;
"FIG. 10 is a cross-section taken along line A-A of FIG. 9;
"FIG. 11 is a plan view of a semi-rigid stiffener of the annuloplasty ring of FIG. 8 with the suturable cover removed and the ends of the stiffener shown in lengthwise cross-section; and
"FIG. 12 is an isometric view of a semi-rigid annuloplasty band of FIG. 8 sewn into the mitral annulus of a heart during ventricular systole."
URL and more information on this patent application, see: Wright,
Keywords for this news article include:
Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC
Most Popular Stories
- Ukraine Crisis Limits Losses in Gold, Silver
- Can GOP Dodge Immigration Bullet?
- Software Writers Sought in Indiana
- Photo ID Required for Unemployment Benefits
- Chiquita, Fyffes to Form Top Banana
- Job Fair for S.C. Grads
- Big Earthquake Rumbles Northern California
- Tech Firms to Increase Hiring for 4th Year in a Row
- China's Money Rate Drops on Slowdown Concern
- '300' Sequel Conquers Box Office Foes