1. Field of the Invention
This invention relates generally to a device for use in the surgical repair of heart pathologies, and, more particularly, to an annuloplasty ring, that exhibits a compressed form or an expanded form depending upon temperature.
2. Description of the Related Art
Human heart valves are sometimes damaged by disease or by aging. Such damage may cause problems with the proper function of the leaflets and/or the sub-valvular apparatus attached to the leaflets. Often, degenerative disease causes the valve annulus to enlarge to the point where the leaflets attached to it cannot fully close. This incomplete closure, a condition called valve incompetence, frequently requires surgical correction either by valve repair procedures or by valve replacement. In the former, also called valvular annuloplasty, various types of ring-shaped devices or bands fashioned from biocompatible cloth-like materials are sewn to the distended annulus. By properly sizing and implanting the annuloplasty ring or band, the surgeon can restore the valve annulus to its normal, undilated, circumference.
While many surgical procedures are now performed using less-invasive techniques, such as endoscopy, valvular annuloplasty continues to be performed primarily using traditional thoracotomy procedures. In a conventional thoracotomy, a large incision is made in the chest wall and, typically, the sternum is divided to gain access to the heart. In a thoracic endoscopic procedure, small incisions are made into the thoracic cavity for passage of an endoscope and other surgical instruments into the thoracic cavity. As compared to traditional thoracotomy, endoscopic methods generally result in less overall trauma to the patient's skin and muscles. Because the patient's internal tissues are not exposed to the operating room atmosphere over long periods of time as in conventional thoracotomy, such procedures typically result in a reduced infection rate. Conventional annuloplasty rings, however, are typically not suitable for use in endoscopic procedures. Generally, these rings and their installation tools are too large to pass through the small endoscopic incisions.
Conventional annuloplasty rings are most typically either highly flexible or are stiff and comparatively rigid. Rigid rings typically consist of an open wire element completely covered with cloth. The wire is somewhat stiff yet resiliently deformable and is not intended to be removable from the cloth covering. These annuloplasty rings, because of their rigidity, lie flat and maintain their somewhat oval shape during implantation. Although a rigid ring's oval shape has been claimed to enhance the competence of the repaired valve, its rigidity can also impede the beneficial flexing movements of the native annulus during the cardiac cycle. Flexible annuloplasty rings generally consist of a soft core of elastomeric material, e.g., silicone rubber, completely enclosed by a sheath of biocompatible cloth. Because of their flexibility, these rings can be difficult to handle during surgical manipulations and generally must be supported during implantation by a holder that is subsequently removed after tying off the implanting sutures.
To overcome some of the deficiencies of flexible and rigid ring structures, an annuloplasty ring would desirably be stiff during handling and implantation, but then become flexible after implantation. As disclosed in U.S. Pat. No. 5,716,397, an annuloplasty ring may consist of a flexible ring into which a rigid structure is inserted to provide temporary rigidity during implantation. Once the ring is implanted and tested, the rigid structure may be removed. However, this approach requires undesirable additional handling after the ring is implanted. Another annuloplasty ring, as disclosed in U.S. Pat. No. 5,104,407, consists of a ring constructed partially of a flexible material and partially of a rigid material. Unfortunately, this type of ring is difficult and costly to manufacture and suffers from the drawbacks afflicting both flexible and rigid rings.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.
In one aspect of the present invention, an annuloplasty ring is provided. The annuloplasty ring includes an elastomeric member and a shape memory member disposed in the elastomeric member enabling the annuloplasty ring to exhibit a compressed form and an expanded form depending on the temperature of the shape memory member. The annuloplasty ring further includes an outer wrap covering the elastomeric member.
In another aspect of the present invention, an annuloplasty ring is provided, including an elastomeric member and a shape memory member disposed in the elastomeric member enabling the annuloplasty ring to exhibit a compressed form and an expanded form depending on the temperature of the shape memory member. The annuloplasty ring further includes an outer wrap covering the elastomeric member and a first end and a second end spaced apart from the first end.
In yet another aspect of the present invention, an annuloplasty ring is provided, including an elastomeric member, a shape memory member disposed in the elastomeric member enabling the annuloplasty ring to exhibit a compressed form and an expanded form depending on the temperature of the shape memory member, and an outer wrap covering the elastomeric member. The annuloplasty ring comprises a saddle shape.
In another aspect of the present invention, an annuloplasty apparatus is provided, comprising an annuloplasty ring and a holder for the annuloplasty ring. The annuloplasty ring includes an elastomeric member, and a shape memory member disposed in the elastomeric member enabling the annuloplasty ring to exhibit a compressed form and an expanded form depending on the temperature of the shape memory member and an outer wrap covering the elastomeric member. The holder includes a handle, a head defining a groove, and a stem extending between the handle and the head, such that the annuloplasty ring, in its compressed form, is retained in the groove. In one aspect, the head comprises a frustoconical head. Such a frustoconical head may have a smaller diameter at a forward end thereof than proximate the stem. Alternatively, such frustoconical head may have a larger diameter at the forward end thereof than proximate the stem.
In yet another aspect of the present invention, a method of training an annuloplasty ring is provided. The method includes providing an annuloplasty ring comprising an elastomeric member; a shape memory member disposed in the elastomeric member enabling the annuloplasty ring to exhibit a compressed form and an expanded form depending upon the temperature of the shape memory member; and an outer wrap covering the elastomeric member. The method further includes bringing the shape memory member of the annuloplasty ring to a temperature above its transformation temperature range and plastically deforming the shape memory member into its expanded shape. Yet further, the method includes bringing the shape memory member to a temperature below its transformation temperature range and plastically deforming the shape memory member into its compressed shape.
In another aspect of the present invention, a method of using an annuloplasty ring including a shape memory member is provided. The method includes inserting the annuloplasty ring in a compressed form into a patient's body and using heat from the patient's body to bring the annuloplasty ring to a temperature above its transformation temperature range to expand the annuloplasty ring into an expanded form.
The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which the leftmost significant digit(s) in the reference numerals denote(s) the first figure in which the respective reference numerals appear, and in which:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
The present invention relates to various embodiments of an annuloplasty ring and its holder that can be used in less invasive surgical procedures. At a temperature lower than a patient's body temperature, the annuloplasty ring exhibits a compressed geometric form that may pass through small incisions or access ports into the patent's body. In this form, the ring is retained on its holder. As the temperature of the ring increases, the annuloplasty ring's form changes and it is released from its holder. At patient body temperatures, the annuloplasty ring has an expanded geometric form suitable for supporting a cardiac valve annulus.
The shape memory member 105 enables the annuloplasty ring 100 to exhibit different geometric forms, such as the compressed form of
While the present invention is not to be limited to the use of any particular shape memory material, examples of shape memory materials that may comprise the shape memory member 105 include:
Shape memory materials are generally relatively weak and pliable when the material is at a temperature below its transformation temperature range. Such materials are generally relatively strong and may have superelastic properties when the material is at a temperature above its transformation temperature range. The properties of a given shape memory material typically vary within its transformation temperature range. The unique properties of shape memory materials enable a structure made of such a material to have one geometric form at a temperature below its transformation temperature range and another geometric form at a temperature above its transformation temperature range. For purposes of the present invention, the working or ambient temperatures of the annuloplasty ring 100 are typically within a range of temperatures found in a patient's body. The transformation temperature range of the shape memory member 105, therefore, falls below the working temperatures of the annuloplasty ring 100. In one embodiment, the transformation temperature range is below about 32° C.
The shape memory member 105 may be processed or “trained” to exhibit the compressed form of
While it may be desirable in some annuloplasty procedures to utilize a “D-type” annuloplasty ring having ends proximate one another, such as the annuloplasty ring 100 of
Studies have shown that some valvular annuli are planar, while others are not. Specifically, the annulus of a mitral valve is generally considered to be “saddle shaped” and, thus, nonplanar. Accordingly,
Sutures, such as the suture 205 shown in
It may be desirable in certain situations to apply sutures (e.g., the suture 205 of
In other situations, it may be desirable to configure a holder for one of the annuloplasty rings 100, 300, 400 that may be more easily inserted through an incision or access port. Accordingly,
As discussed above, each the annuloplasty rings 100, 300, 400 may be trained by plastically deforming the annuloplasty ring 100, 300, 400 either above or below its transformation temperature range to produce the compressed or expanded forms, respectively. In one embodiment of the present invention, illustrated in
In one embodiment, the transformation temperature range of the shape memory member 105 is below about 32° C. Further, in certain embodiments, the shape memory member 105 may be plastically deformed into a generally planar shape (e.g., as in
This concludes the detailed description. The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.