Patent Application: US-27895506-A

Abstract:
this present invention provides a surgical rivet , a rivet deployment actuator , a rivet cutting instrument and a method for securing a prosthetic valve to the heart which has the potential to substantially decrease the ischemic time required for valve implantation and allow larger prostheses to be inserted in small annuli . the surgical rivet is comprised of two flexible preformed elements capable of assuming a preconfigured shape once it is delivered and secured with the deployment actuator . the deployment actuator is a reusable instrument that lowers the prosthesis to the annulus , secures the prosthesis with an “ o ” ring and cuts and deploys the flexible elements so that they rest on the sewing ring of the prosthetic valve . the present invention eliminates the tedious and time - consuming tasks of tying sutures which may be particularly difficult in small annuli . it also automatically cuts the sutures to the appropriate length . the use of single rivets allows for expansion to the annulus and insertion of one full size larger prosthesis than what is possible using the classical horizontal pledget mattress technique . this feature is of particular importance in small annuli where prosthesis / patient mismatch can lead to suboptimal long term results . 1

Description:
this present invention relates to apparatuses and methods for simplifying cardiac valve replacement involving a unique surgical rivet 100 shown schematically in fig1 a - 1b , used to attach a prosthesis sewing ring to a valvular annulus shown in fig9 a . the following description in conjunction with the drawings explains the details of the invention . referring to the drawings , and first to fig1 a , is the surgical rivet 100 comprise of a metallic pledget or stopper 101 , two memory alloy preformed elements 102 encased in a protective sheath 103 causing the elements to be in a high tension or constrained state , attaching the memory alloy elements to a surgical needle 105 . the two preformed elements 102 are wire composed of nitinol or some other memory alloy that can have a circular cross - section shown in fig2 a or non - circular cross - section shown in fig2 b to resist rotation about the elongated direction , permitting the fastener to also resist rotation . the two preformed elements 102 , connected by a metallic pledget 101 as seen in fig3 a - 3b , are movable between a restrained position ( fig1 a - 1b ) and unrestrained position ( fig5 ). the pledget 101 composed of a metallic material is permanently attached to the preformed elements 102 by welding or any other suitable means of connection . fig4 shows how the rectangular shape of the pledget 101 makes it natural for the pledget 101 to align its lengthier side parallel to the annulus 501 . however because of the rotational symmetry of the currently used sutures , the pledget 101 has a tendency to torque out of place at the time of suture placement . but , because the cross - sectional shape of the preformed elements 102 of the present invention is non - circular , which eliminates the rotational symmetry , the pledget 101 is held in place and does not torque . thus , the configuration of the built - in pledget in conjunction with the shape of the preformed elements 102 forces the correct alignment of the rivet 100 to the longitudinal axis of the annulus 501 as illustrated by fig4 . in the pre - deployment state ( fig1 a - 1b ), the preformed elements 102 are parallel and held in tension in an inverted “ t ” shape by the protective sheath 103 . the protective sheath 103 is essentially a hollow elliptical cylinder that fits snugly around the preformed elements 102 and can slide over the preformed element . in the deployed state shown in fig5 , the elements 102 , absent of the protective sheath 103 , are free and assume its natural unrestrained configuration where the ends of the elements are preformed to curl assuming an “ m ” shape . fig6 illustrates an “ o ” ring 201 holding the preformed elements 102 together and securing the connection between a prosthetic valve 500 and annulus 501 . the “ o ” ring 201 is spirally coiled like a spring shown in fig7 or some other configuration that serves the same function . when the ends of the preformed elements 102 are free of the protective sheath 103 , the ends curl in to assume the “ m ” shape which applies tension to the annulus / prosthesis junction . said tension is further reinforced by the “ o ” ring 201 which further secures it in place . since the shape of the “ o ” ring 201 is specially designed to apply a reaction force , it springs back against the ends of the preformed elements so there will always be the same constant net force sandwiching the valve 500 and annulus 501 between the “ o ” ring 201 and the pledget 101 . this eliminates the variability in tension associated with the current conventional suture technique as mentioned previously . included in the present invention is the deployment actuator 200 of fig8 a and fig8 c used to deploy an “ o ” ring 201 and strip the protective sheath 103 off the elements 102 . the deployment actuator 200 comprises of an elongated shaft assembly 202 having a distal end 2021 and a proximal end 2022 with an outer tube 203 that can easily slide over a hollow inner tube 204 . the inner tube 204 is longer than the outer tube 203 and has a slit 205 down the middle for the protective sheath 103 to pass through . at the distal end 2021 portion of the inner tube 204 , which is slightly larger than the opening of the “ o ” ring 201 , the inner tube 204 holds the “ o ” ring 201 in radial tension . to deploy the “ o ” ring 201 the outer tube 203 slides over the inner tube 204 , pushing the “ o ” ring 201 off the inner tube 204 and transferring it onto the preformed elements 102 . also at the distal end portion 2021 but on the inside of the inner tube 204 is a mechanism 206 ( fig8 b ) that strips the protective sheath 103 off the preformed elements 102 . this stripper mechanism 206 is constructed in such a way that when the protective sheath 103 slides into the mechanism 206 nothing is affected . but when the protective sheath 103 slides out , the mechanism 206 is activated and the protective sheath 103 is stripped off the preformed elements 102 . this occurs simultaneously ( fig8 d ) when the inner tube 204 is removed after the “ o ” ring 201 is deployed . once the elements 102 are free of the protective sheath 103 they are no longer constrained and can assume their natural unrestrained “ m ” configuration ( fig8 f ). the valve replacement procedure visualized in fig9 a - 9e embodying this invention includes a surgical rivet 100 comprised of two memory alloy , preformed elements 102 encased in a protective sheath 103 causing the elements 102 to be in a high tension or constrained state , a pledget 101 or stopper at one end and a piercing needle 105 to pass through the tissues at the opposite end . all methods prior to and including trimming of the annular leaflets follow the current standard valve replacement surgical procedure . after the leaflets are trimmed , a surgical rivet 100 is inserted into the annulus 501 using the piercing needle 105 to puncture the annulus 501 and to pull the surgical rivet 100 through until the pledget 101 reaches the annulus ( fig9 a ). the appropriate number of rivets is inserted in the same fashion and the valve is sized . alternative , the rivets 100 can be connected by long strands of flexible wire or other material 106 made of a type of biocompatible material as in fig9 b . the surgeon can choose the appropriate number of rivets 100 by cutting off the excess after the rivets 100 are inserted into the annulus 501 . the protective sheath 103 of the rivet 100 is threaded through the inner tube 204 and exits from the slit 205 shown in fig9 c . fig9 d illustrates how the connection between the prosthetic valve 500 and annulus 501 is tightened . with one hand the surgeon pushes the inner tube 204 down on the sewing ring 500 and with the other hand the surgeon pulls the protective sheath 103 in the opposite direction . the outer tube 203 is slid over the inner tube 204 to transfer the “ o ” ring 201 to the preformed elements 102 . while the outer tube 203 is held against the sewing ring 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