Abstract:
A mounting structure for connecting a device to an organ. The mounting structure includes a mounting element defining a bore. The mounting element is adapted for mounting to an exterior surface of the organ of a living subject. The mounting element includes a collar having a deformable wall defining a main bore. A gimbal ring disposed within the main bore and within the collar is included, the gimbal ring defining a gimbal bore co-axial with the main bore and including a plurality of separate arcuate elements cooperatively disposed in a circumferential direction around the gimbal bore, the plurality of separate arcuate elements being movable toward one another to constrict the gimbal bore.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is related to and claims priority to U.S. Provisional Patent Application Ser. No. 62/273492, filed Dec. 31, 2015, entitled MULTI-PIECE GIMBAL RING, the entirety of which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    n/a 
       TECHNICAL FIELD 
       [0003]    The present invention relates to components and methods used for mounting devices such as ventricular assist devices and associated elements to the heart of a living subject. 
       BACKGROUND 
       [0004]    The heart is sometimes incapable of providing sufficient pumping capacity to meet the needs of the body. The effects of this inadequacy can be alleviated by providing a mechanical pump referred to as a mechanical circulatory support device (“MCSD”). An MCSD can be implanted to supplement the pumping action of the heart, most commonly for an extended period of time such as several years. 
         [0005]    An MCSD is most commonly connected to the left ventricle. In this arrangement, an inlet end of the pump, or an inlet cannula connected to the inlet end of the pump, is implanted in the wall of the ventricle, such as at the apex of the ventricle. An outlet cannula is connected between the outlet end of the pump and an artery such as the aorta. MCSDs which are connected to a ventricle commonly are referred to as ventricular assist devices or “VADs.” During operation, the VAD assists the heart to pump blood from the left ventricle to the aorta. 
         [0006]    Certain MCSDs are typically connected to the heart through the use of a mounting ring, as disclosed in U.S. Published Patent Application Nos. 2004/0171905, 2007/0134993, and 2015/0112120 (“the ‘ 120  Publication”), the disclosures of which are hereby incorporated by reference herein. A mounting ring has a body and a main bore extending through the body, and also has features which can be used to attach the body to the outside of the heart wall so that the bore extends towards and away from the wall. For example, some mounting rings are equipped with a ring of fabric encircling the body, so that the mounting ring can be secured in place by suturing. Other mounting rings are equipped with barbs or other fasteners for attaching the body of the ring to the heart wall. The mounting ring is arranged so that a portion of the body defining at least part of the main bore is compressible to constrict the bore around an element of the MCSD to hold the element in place. As shown, for example, in the aforementioned U.S. Published Patent Application No. 2007/0134993 (“the &#39;933 Publication”), the body may include a base plate which faces toward the body when the ring is installed, and a pair of generally C-shaped arms encircling the main bore. The arms have fixed ends attached to the base plate near one location on the circumference of the bore. At least one of the arms is attached to the base plate only at and near its fixed end, so that the portion of the arm remote from the fixed end is free to bend towards the opposing arm. A clamp is provided for squeezing the arms together to constrict the main bore. 
         [0007]    The mounting ring may also incorporate an element referred to as a gimbal ring. The gimbal ring is a generally hoop-shaped element which defines a gimbal ring bore. The gimbal ring is disposed inside the main bore defined by the body. The gimbal ring may have a spherical outer surface, and the main bore may have a corresponding interior surface, so that the gimbal ring can pivot to tilt the axis of the gimbal ring bore relative to the main bore and thus relative to the body of the mounting ring. The gimbal ring typically is formed from a relatively hard polymeric material, and is provided with a slot extending through the wall of the ring at one point around its circumference. Thus, when the main bore is constricted, the mounting ring can be compressed slightly to constrict the gimbal ring bore. 
         [0008]    A one-way valve may be mounted within the gimbal ring bore. The one-way valve typically is formed as a tubular or ring-like structure with flaps or collapsible sections which can close to occlude the gimbal ring bore. 
         [0009]    In use of such a mounting ring, the base of the body is secured to the outside of the heart. A cruciate cut is made in the heart wall within the gimbal ring bore and a separate surgical tool is used to core a hole in the heart. The valve temporarily occludes the gimbal ring bore to prevent massive blood loss when the coring tool is removed. A pump, an inlet cannula or other element of an MCSD is, is then inserted through the interior of the valve and through the gimbal ring bore into hole into the heart. The gimbal ring can be tilted to align the axis of the MCSD element with the anatomical features of the heart. Once the MCSD element has been positioned as desired, clamp is tightened to constrict the main bore and thus constrict the gimbal ring bore to secure the MCSD element in position. The MCSD element must be secured so as to remain in place during operation, despite the loads imposed by the beating heart and by movement of the patient. While mounting rings of this type have been very effective, it is sometimes difficult to tighten the clamp sufficiently. 
       SUMMARY 
       [0010]    The present invention advantageously provides for a mounting structure for connecting a device to an organ. The mounting structure includes a mounting element defining a bore. The mounting element is adapted for mounting to an exterior surface of the organ of a living subject. The mounting element includes a collar having a deformable wall defining a main bore. A gimbal ring disposed within the main bore and within the collar is included, the gimbal ring defining a gimbal bore co-axial with the main bore and including a plurality of separate arcuate elements cooperatively disposed in a circumferential direction around the gimbal bore, the plurality of separate arcuate elements being movable toward one another to constrict the gimbal bore. 
         [0011]    In another aspect of this embodiment, the plurality of arcuate elements includes at least three arcuate elements. 
         [0012]    In another aspect of this embodiment, a deformable element is included, the deformable element being more readily deformable than the plurality of separate arcuate elements, the deformable element being configured to connect the plurality of separate arcuate elements with one another. 
         [0013]    In another aspect of this embodiment, the deformable element includes a resilient tube sized to be disposed within the gimbal bore. 
         [0014]    In another aspect of this embodiment, the deformable element defines a one-way valve within the gimbal bore. 
         [0015]    In another aspect of this embodiment, the plurality of arcuate elements is configured to attach to the resilient tube. 
         [0016]    In another aspect of this embodiment, at least one of the plurality of separate arcuate elements is slideably engaged with at least one other of the plurality of arcuate elements to provide movement relative to one another in the circumferential direction. 
         [0017]    In another aspect of this embodiment, the plurality of separate arcuate elements cooperatively define an exterior surface having a shape substantially in the form of a spherical segment. 
         [0018]    In another aspect of this embodiment, each of the plurality of separate arcuate elements includes a slot at a first end and a projection at the opposite second end. 
         [0019]    In another aspect of this embodiment, a flexible strip disposed between each of the plurality of separate arcuate elements is included. 
         [0020]    In another aspect of this embodiment, the deformable element includes projections configured to couple with corresponding gaps in the gimbal ring. 
         [0021]    In another embodiment, the mounting structures includes a mounting element defining a bore. The mounting element is adapted for mounting to an exterior surface of the heart of a living subject. The mounting element includes a collar having a deformable wall defining a main bore. A clamp is engaged with the collar, the clamp being arranged to deform the collar so as to constrict the main bore. A gimbal ring is disposed within the main bore, the gimbal ring defining a gimbal bore co-axial with the main bore and including a plurality of separate arcuate elements cooperatively disposed in a circumferential direction around the gimbal bore, the plurality of separate arcuate elements being movable toward one another to constrict the gimbal bore. The plurality of separate arcuate elements are movable from an unconstricted condition in which a gap is defined between adjacent arcuate element and a constricted condition in which the gaps are closed. 
         [0022]    In another aspect of this embodiment, the main bore defines a longitudinal axis there through, and wherein the collar defines a first slot substantially parallel with the longitudinal axis. 
         [0023]    In another aspect of this embodiment, the collar defines a second slot between the mounting element and the collar. 
         [0024]    In another aspect of this embodiment, the plurality of separate arcuate elements are substantially rigid. 
         [0025]    In another aspect of this embodiment, a deformable tube is included, the deformable tube being more readily deformable than the plurality separate of arcuate elements, the deformable tube being configured to connect the plurality of separate arcuate elements with one another. 
         [0026]    In another aspect of this embodiment, the deformable element defines a one-way valve within the gimbal bore. 
         [0027]    In another aspect of this embodiment, at least one of the plurality of arcuate elements is slideably engaged with at least one other of the plurality of arcuate elements to provide movement relative to one another in the circumferential direction. 
         [0028]    In another aspect of this embodiment, each of the plurality of separate arcuate elements includes a slot at a first end and a projection at the opposite second end. 
         [0029]    In yet another embodiment, the mounting structure includes a mounting ring defining a bore. The mounting ring is adapted for mounting to an exterior surface of the heart of a living subject. The mounting ring including a collar having a deformable wall defining a main bore. A clamp is engaged with the collar, the clamp being arranged to deform the collar so as to constrict the main bore. A gimbal ring is disposed within the main bore, the gimbal ring defining a gimbal bore co-axial with the main bore and including a plurality of separate arcuate elements cooperatively disposed in a circumferential direction around the gimbal bore, the plurality of separate arcuate elements being rigid and movable toward one another to constrict the gimbal bore. A deformable tube is included, the deformable tube defining a one-way valve and being more readily deformable than the plurality separate of arcuate elements, the deformable tube being configured to connect the plurality of separate arcuate elements with one another. Each of the plurality of separate arcuate elements includes a slot at a first end and a projection at the opposite second end, and at least one of the plurality of arcuate elements is slideably engaged with at least one other of the plurality of arcuate elements to provide movement relative to one another in the circumferential direction. The plurality of separate arcuate elements being movable from an unconstricted condition in which a gap is defined between adjacent arcuate element and a constricted condition in which the gaps are closed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    A more complete appreciation of the subject matter of the present invention and the various advantages thereof can be realized by reference to the following detailed description, in which reference is made to the accompanying drawings: 
           [0031]      FIG. 1  is a diagrammatic exploded view of a mounting structure according to one embodiment of the invention; 
           [0032]      FIG. 2  is a fragmentary sectional view of an element in the structure of  FIG. 1 ; and 
           [0033]      FIG. 3  is a fragmentary elevational view of a component used in a structure according to a further embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Referring now to the drawings in which like reference designators refer to like elements, there is shown in  FIG. 1  a mounting structure constructed in accordance with the principles of the present application and designated generally as “ 8 .” The mounting structure  8  according to this embodiment includes a mounting element or body  10  in the form of a mounting ring  10 . In one configuration, mounting ring  10  includes a base plate  12  and a collar  14  projecting from a proximal side  13  of the base plate  12 . In one configuration, the collar  14  is cylindrical and in other embodiments may be other shapes. A main bore  16  having a main bore axis  18  extends through mounting ring  10  and is coaxial with collar  14 . In one configuration, the main bore  16  extends through the entire length of the collar  14  and through the base plate  12 . 
         [0035]    The collar  14  may further define a first slot  20  extending through a wall  15  of collar  14  and extending parallel to the main bore axis  18 . The wall  15  of collar  14  may be formed integrally with the base plate  12  or otherwise secured to the base plate  12  around a portion of the circumference of bore  16 . The height of the wall  15  and the thickness of the wall  15  may vary in different configurations. In the configuration shown in  FIG. 1 , the height of wall  15  is greater than the height of the base plate  12 . The collar  14  may further define a second slot  22  extending around at least a portion of the circumference of the main bore  16  configured separate at least a portion of the wall  15  of collar  14  from the base plate  12  around this portion of the circumference. Stated another way, a portion of the wall  15  of collar  14  defines a generally C-shaped arm having a free end  24  adjacent first slot  20  and a fixed end  26  that is fixed to the base plate  12  by the remainder of the collar  14 . This arm may be moved toward the opposite site of the collar  14  so as to bend it inwardly and thereby constrict main bore  16 . In one configuration, the interior surface of collar  14  defining the main bore  16  is substantially in the form of a zone of a sphere or spherical segment. 
         [0036]    Continuing to refer to  FIG. 1 , mounting element  10  is provided with a structure suitable for attaching the base plate  12  to the exterior surface of a human or animal patient&#39;s heart. In this embodiment, that structure includes a ring of suturable material  26  secured to the periphery of base plate  12 . For example, the suturable material may include a layer of a fabric or felt and may also include a layer of a tough polymeric material such as a polymer sheet. In one configuration, ring body  10  may be secured to base plate  12  by sutures (not shown) extending through apertures (not shown) in the base plate or by any other structural attachment. Other structures suitable for attaching the base plate to the heart wall include mechanical anchors such as barbs or hooks disposed around the periphery of the base plate. One scheme employing such mechanical anchors is shown in the aforementioned &#39;120 Publication. In still other embodiments, mechanical anchors such as staples may be inserted through apertures (not shown) in the base plate. 
         [0037]    A clamp  28  is schematically depicted as an eccentric cam that can be rotated about an axis parallel to the main bore axis  18 . When clamp  28  is rotated from the position shown, a portion of the clamp  28  bears on the arm defined by wall  15  and force the free end of the arm toward first slot  20 , thus constricting main bore  16 . In actual practice, the clamp  28  may include additional elements such as a movable element disposed between the cam and the wall  15  of the collar. For example, the clamp  28  may be as disclosed in U.S. Published Patent Application 2015/0359952, the disclosure of which is incorporated by reference herein. Other forms of clamps may be employed. For example, a clamp may include a screw having a head carried on one portion of the collar  14  and threadably received in the opposite portion of the collar  14 , so that rotation of the screw constricts the collar  14  and thus constrict the main bore  16 . In yet another arrangement, clamp  28  may include a screw (not shown) threadably engaged with the base plate  12  for movement along an axis parallel to the bore axis  18 . The screw may have a beveled head forming a cam surface. As the screw is advanced, the beveled head is forcibly engaged with a movable element mounted to the base plate  12 , thus urging the movable element against the collar  14  to force the collar  14  into a constricted configuration when the screw is advanced. The mounting element  10  and clamp  28  may be of any construction which allows for constriction of the mounting element bore  16 . 
         [0038]    The mounting structure  8  according to one embodiment includes a gimbal ring  30 . The gimbal ring  30  includes a plurality of separate arcuate pieces  32 ,  34 , and  36 . Piece  32  has a projection  38  extending generally in the arcuate or circumferential direction at one end and a slot  40  at the opposite end. Each of the other pieces  34  and  36  have corresponding projections and slots. When the pieces are in an assembled, unconstricted condition as shown in  FIG. 1 , the projection  38  of each piece is received in the slot  40  of an adjacent piece. In this condition, there is a gap  41  between the end of arcuate piece  32  and the end of the next adjacent arcuate piece  36 , with the projection of piece  36  extending across the gap  41  and into slot  40 . There is a similar gap between the end of piece  34  and the adjacent end of piece  32 , and another similar gap between the end of piece  36  and the adjacent end of piece  34 . The three pieces  32 ,  34 , and  36  cooperatively define a ring having a gimbal ring bore  42 , with the arcuate pieces  32 ,  34 , and  36  being circumferentially disposed around the axis  44  of the gimbal ring bore  42 . The interior wall of the gimbal ring bore  42  defined by pieces  32 ,  34 , and  36  is substantially cylindrical. The exterior surface of the ring  30 , also defined by pieces  32 ,  34 , and  36  has a configuration complimentary to the spherical configuration defined by wall  14 ; the exterior surface of the ring is substantially a zone of a sphere or a spherical segment. 
         [0039]    In the assembled but unconstricted condition shown, the end of each piece  32 ,  34 , and  36  is free to move toward the end of the next adjacent piece  32 ,  34 , and  36 . This motion is accommodated by sliding a respective projection  38  disposed at a first end  39  of each piece  32 ,  34 , and  36  and within a respective slot  40  disposed at a second end  43  opposite the first end  39 . Thus, the ends  39  and  43  of the pieces  32 ,  34 , and  36  are free to be displaced toward one another in the circumferential direction around axis  46 , thus bringing the gimbal ring  30  to a constricted configuration in which the diameter of the gimbal ring bore  42  is reduced and the gap  41  is closed. It should be appreciated that such movement does not require deformation of the arcuate pieces  32 ,  34 , and  36 . Rather, the gaps  41  between the arcuate pieces  32 ,  34 , and  36  are closed during movement from the conditions shown in  FIG. 1  to a constricted configuration. Because the pieces  32 ,  34 , and  36  of the gimbal ring  30  need not deform as the gimbal ring  30  is constricted, the pieces  32 ,  34 , and  36  can be formed from a relatively rigid material such as a stiff polymer. 
         [0040]    The mounting structure  8  according to this embodiment further includes a deformable element or tube  50  in the form of a thin tube of a rubber-like material. The tube  50  is hollow, as best seen in  FIG. 1 . Deformable element or tube  50  is formed integrally with three flaps  52  which form a valve. In the closed configuration shown in  FIG. 1 , flaps  52  cooperatively occlude the interior of the tubular member. In one configuration, pieces  32 ,  34 , and  36  of the gimbal ring  30  are secured to the exterior surface of the tube or deformable element  50 . When secured to the deformable element  50 , the pieces  32 ,  34 , and  36  are in the unconstricted or expanded configuration shown in  FIG. 1 . The pieces  32 ,  34 , and  36  of the gimbal ring  30  may be secured to the deformable element  50 , for example, by bonding the interior surfaces of the pieces to the wall of the deformable element  50 . Optionally, deformable element  50  may have projections  56  on its exterior surface, and these projections can be engaged within the gaps  41  between adjacent pieces  32 ,  34 , and  36  of the gimbal ring.  30 . The tube  50  also optionally may have further projections  58  on its exterior surface to hold the pieces  32 ,  34 , and  36  of the ring in a generally coplanar arrangement. In this condition, the deformable element  50  holds the pieces  32 ,  34 , and  36  together to provide a subassembly that can be readily handled. The subassembly can be assembled to mounting element  10  by inserting the deformable element  50 , with the pieces  32 ,  34 , and  36  of the ring  30  thereon, into the main bore  16  of mounting element  10 . During this process, the ring  30  may be temporarily constricted as, for example, by the operator&#39;s hand or by a fixture (not shown). Once the pieces  32 ,  34 , and  36  of ring  30  are disposed within the bore  16 , the resilience of the deformable tube  50  tends to push the pieces  32 ,  34 , and  36  outwardly and thus restore the ring  30  to its unconstructed configuration. In this configuration, the spherical exterior surface defined by ring  30  bears on the spherical interior surface defined by the wall of main bore  18  in the mounting element  10 . In this condition, the axis  46  of the ring bore  16  is generally coaxial with the axis of main bore  18 . 
         [0041]    The mounting structure  8  may be used in the normal manner. Thus, mounting element  10  is secured to the exterior surface of the heart wall as, for example, by suturing material  26  to the wall of the heart or by actuating other fastening devices (not shown). A hole is formed in the wall of the heart through valve  54  and through the gimbal ring bore  42  and main bore  18  to the surface of the heart and forming a cruciate cut. Following the cruciate cutting operation, a coring tool (not shown) may be inserted through the valve to form an open hole in the heart. The coring tool is then withdrawn and an element of an MCSD (not shown) such as a body of a pump or an inlet cannula is inserted through the valve, through the gimbal ring bore  42 , and through the main bore into the heart. The MCSD element may be tilted as desired. This tilting motion is accommodated by pivoting motion of the gimbal ring  30  within the main bore  16 . The spherical surface formed by pieces  32 ,  34 , and  36  of the gimbal ring  30  provides a pivoting action and allows accurate alignment of the MCSD element with the anatomical features as desired. Once the desired alignment has been achieved, clamp  28  is actuated so as to deform the wall defining main bore  16  and constrict the main bore. This drives the pieces  32 ,  34 , and  36  of gimbal ring  30  towards a constricted configuration in which the gaps  41  between the ends of the pieces  32 ,  34 , and  36  are diminished, thus constricting the gimbal ring bore  42  and securely clamping the MCSD element within the gimbal ring  30  and within the mounting element  10 . Because the pieces  32 ,  34 , and  36  of the gimbal ring  30  are free to move relative to one another in the circumferential direction, they offer little or no resistance to constricting movement. This, in turn, reduces the forces that must be applied to collar  14  by clamp  28  and reduces the forces required to actuate clamp  28 . During this process, the adhesive bond between the pieces  32 ,  34 , and  36  of the gimbal ring  30  and the deformable element  50  may be broken or may remain intact. In either configuration, because the deformable element  50  is formed from a material that is more deformable than the arcuate pieces  32 ,  34 , and  36  of the mounting ring  10 , the deformable element  50  offers essentially no resistance to the constricting movement. Numerous variations of the features discussed above can be used. For example, it is not essential for the deformable element  50  connecting the arcuate pieces  32 ,  34 , and  36  of the gimbal ring  30  to be a tubular element as shown. The deformable element  50  may be an  0 -ring or other structure which does not include a valve. 
         [0042]    Now referring to  FIG. 3 , in another configuration gimbal ring  130  may include thin, flexible structures such as strips  150  extending across the gaps  141  between adjacent arcuate pieces  132  and  134  of the gimbal ring  130 . These strips  150  may be formed integrally with the arcuate pieces  132  and  134 . The strips  150  may sufficient strength to hold the gimbal ring  130  together during handling and assembly, but do not materially impede movement of the arcuate pieces during constriction of the gimbal ring  130 . 
         [0043]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention.