Abstract:
A device useful for implantation at a native heart valve can include an anchor element having a tubular configuration defining a longitudinal direction and a circumference, a heart valve prosthesis disposed within the anchor element, and a plurality of elongate members positioned at equidistant angular intervals about the circumference of the anchor element. The device can be configured to be transitioned from a radially collapsed delivery configuration to a radially expanded implantation configuration, and the plurality of elongate members can have a length extending in the longitudinal direction of the tubular member in the expanded implantation configuration.

Description:
STATEMENT OF RELATED APPLICATIONS 
       [0001]    This application is a continuation under 35 U.S.C. §120 of U.S. application Ser. No. 14/019,071, filed Sep. 5, 2013, now pending, which is a continuation under 35 U.S.C. §120 of U.S. application Ser. No. 13/279,800, filed Oct. 24, 2011, now U.S. Pat. No. 8,585,756 B2, which is a continuation under 35 U.S.C. §120 of U.S. application Ser. No. 12/138,983, filed on Jun. 13, 2008, now U.S. Pat No. 8,216,301 B2, which is a continuation under 35 U.S.C. §120 U.S. application Ser. No. 10/210,085, filed on Aug. 2, 2002, now abandoned, which applications are incorporated herein by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The current invention relates to an implant implantation unit and to a procedure for fitting the unit in a tubular element. 
         [0003]    The problem at the origin of the invention concerns the implantation of heart valves. Until recently this necessitated open heart surgical operations, with stages such as stopping the heart, the implementation of extra bodily blood circulation and restarting the heart after the implantation of replacement heart valves. These surgical operations are difficult and delicate and present mortal risks related to operating shocks. 
       BACKGROUND 
       [0004]    U.S. Pat. No. 5,824,063 thus describes a unit carrying replacement heart valves, the unit comprising a tubular implant in synthetic material carrying internally a replacement valve in natural material. 
         [0005]    U.S. Pat. No. 5,855,601 and U.S. Pat. No. 5,868,783 describe new heart valve implantation methods, which offer the advantage of avoiding open heart surgery. These methods provide the implantation, by movement through the blood circulation system, of a heart valve replacement unit comprising a radially expandable intra-vascular cylinder carrying a biological valve internally. An inflatable part of a balloon catheter is placed inside the carrier cylinder and the implantation is done by introduction into a vein and movement as far as the failed valve using A catheter. A two dimensional image screen display allows the detection that the carrier cylinder has reached the required position and the cylinder is then dilated by inflating the balloon through the catheter and maintains its expanded shape. The balloon is then deflated and withdrawn with the catheter. 
         [0006]    The carrier cylinder presents a sealed casing, which is thus forced against the artery wall, so as to avoid the blood flow bypassing the replacement valve. 
         [0007]    However, when the aorta is involved this procedure is not applicable because the coronary arteries open close to the failed native valves, so that the carrier cylinder is likely to block them, provoking the death of the patient. 
       SUMMARY 
       [0008]    The inventors of the present application have therefore thought of providing two corresponding openings in the wall of the carrier cylinder casing. However, so that these openings will be placed opposite the two coronaries, the position of the carrier cylinder in the aorta must be completely controlled. Monitoring on the screen allows the progress, or axial position, of the carrier cylinder to be checked, but the angular position will be neither visible nor controlled. 
         [0009]    The applicants have therefore found a solution, described below, allowing the position of the carrier cylinder to be controlled. 
         [0010]    They have therefore thought about the resolution of the more general problem of positioning an implant unit or transport vehicle in a tubular element with difficult access and for which imaging is insufficient or even impossible. The field of application could thus concern other fields than the medical, such as the petroleum or nuclear industries, for installing sensors, valves and other items. The scope of the present application must therefore not be considered as limited to the resolution of the original problem. In a more general way, the invention aims to allow, the placing, in a difficult to access location of a tubular element, of a unit intended to carry an implant, whatever the function of the implant. 
         [0011]    To this end, the invention concerns in the first place a unit for the implantation in a determined position of a tubular element with a wall comprising a cavity, the unit being arranged to cooperate with means for driving the unit in the tubular element, a unit characterized by the fact that it comprises deformable feelers arranged so that, under the control of means for remote activation, it passes from a stowed to a deployed functional shape, to detect the cavity and position itself there with reference to the position of the cavity. 
         [0012]    Thus, the unit can be made to advance blind and the feelers allow the automatic detection of the cavity and positioning at it. 
         [0013]    The final required position can also be reached even through a contraction of the tubular element for example an access artery leading to an artery of larger diameter. 
         [0014]    The invention also concerns a process, which is not surgical and without therapeutic aim, for implantation of the inventive unit, at a predetermined position in a tubular element presenting a wall comprising a cavity which procedure is characterized by the fact that 
         [0015]    a user inserts the unit through an open end of the tubular element 
         [0016]    he activates drive means to make the unit advance to a position before the determined position, 
         [0017]    he commands the feeler remote activation means and, with the advance continuing, 
         [0018]    he stops the action of the drive means when he detects a blockage of the advance, indicating that the feeler means are positioned in the cavity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The characteristics and advantages of the present invention will appear more clearly with the aid of the following description of a particular form of the realization of the inventive unit and a variant, as well as the procedure for using it, with reference to the attached drawing, in which: 
           [0020]      FIG. 1  is a lateral cross section of the inventive unit, representing the feeler positioning and anchoring elements, associated with a cylinder carrying a valve prosthesis, the whole being covered by two removable concentric activation casings, 
           [0021]      FIG. 2  corresponds to  FIG. 1 , the feeler positioning and anchoring elements having been deployed radially by axial withdrawal of the external casing, 
           [0022]      FIG. 3  corresponds to  FIGS. 1 and 2 , with the carrier cylinder surrounded by positioning and anchoring feeler elements having been deployed radially after axial withdrawal of the internal casing, 
           [0023]      FIG. 4  is a lateral view of the carrier cylinder and the positioning and anchoring feeler elements, 
           [0024]      FIG. 5  is a lateral perspective view of the positioning and anchoring feeler elements, 
           [0025]      FIG. 6  is a schematic face view of the inventive unit, and 
           [0026]      FIG. 7  is a schematic lateral section of the variant. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    As shown in  FIG. 1 , the present implementation example corresponds to the medical problem, explained at the beginning, of implanting a functioning replacement valve for the native aorta valve. The valve implantation unit  10  comprises a carrier element  20  to hold the implant, joined to a plurality of feeler, or palpation, elements or fingers  30 ,  31 , here regularly spaced angularly all around, for positioning and anchoring relative to relief features, specifically a cavity in the aorta wall, unit  10  being linked removably to a positioning catheter  60 . Unit  10  is associated with two concentric sleeves  41 ,  42  for successive remote activation, by radial expansion, of feeler elements  30 ,  31  then the carrier element  20 . The direction of movement of unit  10  is therefore towards the left in  FIGS. 1 to 3 . Reference  62  represents an axis of symmetry and the drive direction of unit  10  and catheter  60 . 
         [0028]    The implantation valve forms a prosthesis  1  comprising valve units  2  of the valve whose shape and size correspond perfectly, in the operating position, to those of the native aorta valves  50  ( FIG. 2 ). The prosthesis  1  is fixed to the implant holding carrier vehicle element  20 , here comprising a cylindrical mesh in a bio-compatible material such as steel, gold alloys and for preference as here, nitinol, which comprises a shape memory nickel-titanium alloy offering the ability to regain its shape after initial deformation, here by radial compression. The fixing of prosthesis  1  to the cylindrical nitinol mesh is made in well-defined locations leaving free those regions that correspond to the valve units  2  after deployment from the stowed position of  FIG. 2 , as illustrated below in respect of  FIG. 3 . 
         [0029]      FIG. 4  represents the cylindrical mesh  20  in the deployed form, carrying the valve units  2  also deployed internally, on which are connected the feeler elements  30 ,  31 , here in the form of a generally cylindrical exterior ring of wire loops of which one ( 31 ) at least, here in fact three, protrudes laterally and towards the front, opposite the catheter  60 . In this example, the loops  31  extend, in the deployed position, in a direction inclined at about 30 degrees towards the front (direction of movement towards the target position) relative to the axis  62  of the mesh  20  and the ring  30 . The feeler elements  30 ,  31  are joined to the cylindrical mesh  20  in such a way that their axial and angular positions relative to it are perfectly defined. The assembly, cylindrical mesh  2  and feeler elements  30 ,  31 , is here composed of the auto expandable bio-compatible material mentioned above. 
         [0030]    The cylindrical carrier mesh  20  is here covered with an impermeable lateral casing intended to be pressed against the aorta wall to avoid bypassing by the blood circulation. 
         [0031]      FIG. 5  shows the feeler elements  30 ,  31  in perspective.  FIG. 6  is a schematic view, along the unit  10  axial direction, showing the three loops  31  protruding laterally from the tubular grid  20  that carries them, while the  2  valve units of the valve to be implanted are fixed internally to the carrier cylinder  20 . 
         [0032]    In addition, if necessary, an inflatable balloon, joined to the catheter  60 , can here be placed inside the carrier cylinder  20 , to be fed with liquid under pressure through catheter pipe  60  so as to cause or assist the radial expansion of the carrier cylinder  20  to the required deployed form. 
         [0033]    As the feeler elements  30 ,  31  are made in a self-expanding material such as nitinol, or an equivalent element forming an elastically protruding foot or finger, unit  10  is covered with an inhibition sleeve  42  to hold the feeler elements  30 ,  31  in a stowed position, the loops  31  being folded on the ring  30  and thus also on the mesh  20 . Sleeve  42  extends to cover the catheter  60 . A second sleeve  41 , effectively the same length and without effect on the feeler elements  30 ,  31 , is here similarly provided to hold the carrier cylinder  20  in the stowed position, so as to avoid unplanned deployment even in the absence of inflation of the balloon  3 . The two sleeves  41 ,  42 , are mounted concentrically on the catheter  60 . The sleeves  41  and  42  are accessible from the end of catheter  60  opposite to the unit  10 . Elements  3 ,  41 ,  42 , and  60  comprise a functional catheter assembly separable from the unit  10 , for the positioning and switching on this latter and the payload ( 2 ). 
         [0034]    The two sleeves  41 ,  42  inhibit the radial deployment or the structure  20 ,  30 ,  31  until the latter reaches the region of the native aorta valve  50  to be functionally replaced, and thus allow the introduction of unit  10  into the blood circulation system, such as a reduced diameter incised artery. As indicated, the catheter  60 , with balloon  3 , is detachably joined to the implantation unit  10  so as to allow an axial advance of the implantation unit  10  in the blood circulation system up to the implantation location, and the withdrawal of the catheter assembly  3 ,  41 ,  42 ,  60 . 
         [0035]    To free itself, the catheter  60  comprises, in this example, at the fixed end of carrier cylinder  20 , a spring effect clamp (not shown), with remotely controlled teeth, fitted to rotate radially, for connection to the unit  10  and has a sliding central remote control metal wire to axially push back the claw branches or teeth so as to separate them radially and so free the catheter  60  of the implantation unit  10  according to the sugar claw principle. 
         [0036]    When the cylindrical mesh  20  is deployed, the pressure on the aorta internal wall is provided by the shape memory effect, which thus ensures the radial dilation of the prosthesis  1 . The failed native valve unit  50  is flattened by being pressed by the tubular grid  20  against the aorta internal wall, each of the three loops  31  protruding laterally having previously been engaged in one, specifically, of the three native valve units  50  and being similarly pressed to confirm its anchorage. The valve units  50  are thus clamped between the mesh  20 ,  30  and the respective loops  31 . 
         [0037]    The implantation procedure for the unit  10  described above, according to the preferred method of implementation, comprises the following steps. After insertion of the implantation unit  10  into the circulatory system, and after having pushed it using the catheter  60  to a position above the final target position, here precisely where the unit  10  arrives in the aorta, and so that a large diameter space is thus offered to it, the following stage consists of freeing the lateral loops  31 , initially pressed against the stowed mesh  20 ,  30 . The release of the loops  31  is done by withdrawing the external retention sleeve  42  ( FIG. 2 ), that is to say withdrawn whilst maintaining the thrust on the catheter  60 . The forward movement of the unit  10  continuing, the loops  31 , being then protruded laterally towards the front with respect to the axial direction of forward movement, in opposition to the catheter  60 , they form a sort of tripod and simultaneously penetrate the three respective native valves  50 , effectively identical, comprising an arrangement of connection pockets in a complete ring with each extending over 120 degrees, filling in total the whole of the perimeter of the aorta internal wall  51 . Each native valve unit  50  offers a rounded base. 
         [0038]    Each lateral protrusion  31 , turned towards the front, presses against the base of the native valve unit  50  concerned, in general in a point distant from the “lowest” point of the base, that is to say, the furthest from the catheter  60 . This is therefore a partial stop because the axial advance of the unit  10  continues by thrust from the catheter  60 , the axial thrust of the unit  10  causing it to slide to the lowest point. The bottom of the valve unit  50  thus comprises a sort of inclined plane guidance track (not orthogonal to the axis ( 62 ) of the aorta) which, in reaction to the axial forward force, creates a circumferential reaction force causing the rotation of the unit  10  until the feeler loop considered  31  reaches the lowest point, which corresponds to a complete end wall (with tangential plane orthogonal to the axis ( 62 ) of the aorta  51 ), and thus corresponds to the final axial and angular position sought for the unit  10 . 
         [0039]    Each lateral protrusion  31 , with rounded ends, here as a loop, so as to be able to slide in the bottom of the valve unit  50 , thus comprises, by continuous cooperation with the variable depth rounded base of the native valves  50 , means for rotational drive of the feeler elements  30 ,  31  and thus also of the cylindrical mesh  20 , to which it is joined. However if the lateral protrusions  31  by chance bump against a native valve unit  50  commissure, the implantation unit  10  can be slightly withdrawn and the operator twists the catheter  60  so that it pivots angularly to be able to restart the positioning and anchoring operation. 
         [0040]    The assembly, feeler elements  30 ,  31  and cylindrical mesh  20 , being positioned axially and at an angle with respect to the specific relief of the aorta comprising the native valve units  50 , it is then automatically positioned with respect to the two coronary openings ( 52 ) for which the axial and angular position with respect to the valve units  50  is determined and known, the valve unit-coronary axial distance evidently depending on the size of the patient. 
         [0041]    In the case considered here in which the three native valves  50  form a circular circumference to the aorta wall extending over 360 degrees, a single lateral protrusion is sufficient to modulo 120 degrees positioning and anchoring the cylindrical mesh  20 . As stated above, in a general case, there could only be one feeler  30 ,  31  working with a row of cavities or pockets covering all the circumference of the tubular element, or even a single pocket of cavity  50  only occupying a sector of the circumference and a plurality of feelers  30 ,  31  all around the unit  10  so that one of them fits in the cavity. 
         [0042]    It will be noted that, in the present example, modulo  120  degrees positioning can be tolerated because the two coronaries ( 52 ) naturally effectively show this angle. If this was not the case, it would be necessary laterally to enlarge two openings or serrations  22  provided in the casing  21  so that they were positioned opposite the coronaries ( 52 ) ( FIG. 4  and position marked on  FIG. 3 .), or again to feel, using the feelers  31 , the coronaries ( 52 ) themselves, which also comprise cavities in the aorta  51 , and not to sense the native valve units  50 . This case corresponds to the variant described below. 
         [0043]    Positioning thus having been effected, the following stage, as show in  FIG. 3 , consists of deploying the cylindrical mesh  20  carrying internally the valve units  2  by withdrawing the internal retaining sleeve  41 , to consolidate the anchorage and change the valve units  2  to their operational form. For the clarity of the drawing, in particular the protrusions  31 , the mesh  20  has been represented with a relatively small diameter, whereas in fact it matches that of the aorta  51 , with a slight increase to ensure the required lateral pressure. In the same way, two protrusions  31  have been represented, although in fact they are separated by 120 degrees, with the plane of  FIG. 3  only in reality cutting one. For this reason, only a single coronary has been drawn ( 52 ). 
         [0044]    The three loops  31  protruding however provide by themselves a basic anchorage in the bottom of the pockets comprising the native valves  50  and ensure the positional stability of the prosthesis  1 . After a few weeks, fibrous tissue will cover the prosthesis  1 , combining with the lateral protrusions  31  to further improve the fixing. 
         [0045]    It will be noted however that, in the deployed position of the feeler elements  31 , it is not necessary that their free ends should be firmly pressed against the aorta  51  wall. It is sufficient that their radial extension should be sufficient that they hook, in passing, onto the valve units  50 . Because of this, when the feeler elements  31  are deployed, before the final position, the later axial translation of the unit  10 , up to this position, is done without “hard” rubbing under pressure, of the part of the loops  31  on the aorta wall  51 . The latter thus does not run any risk of damage due to scratching or piercing, the loops  31  being feelers, that follow the aorta wall  51  to detect the valve units  50 . As described above, rounded feet or lugs can also be suitable. 
         [0046]    The feeler loops  31  thus do not here have very firm anchoring of the unit  10  in the aorta  51  as their main function, because they do not aim to exert a large radial anchoring pressure. As indicated above, this is only a basic anchoring. It is then the radial deployment of the mesh  20  that creates, by shape memory, a definitive radial anchoring pressure that forces the mesh  20  under pressure against the aorta wall  51  and thus blocks any relative movement, such as the withdrawal of the unit  10  that could be due to blood flow, in a direction opposite to the insertion of the unit  10 . The feeler elements  11  are then functionally superfluous. They however contribute to maintaining position by pinching the valve units  2 . As the mesh offers a relatively high contact surface with the aorta  51 , any risk of damaging the latter is excluded. The shape memory material allows the radial pressure exerted on the aorta  51  to be precisely determined, the diameter of the latter thus increased being then perfectly defined, which eliminates all risk of excessive radial stress. 
         [0047]    The inventive procedure can be implemented in non-surgical manner and without therapeutic aims, to implant the unit  10  (or equivalent) in a determined position in a tubular elements offering a wall including a cavity, the procedure comprising the following stages: a user inserts the unit ( 10 ) into an open end to the tubular element, the user activates the drive means ( 60 ) (catheter, external magnet or other) to move the unit ( 10 ) up to a position upstream the determined position, the user commands the feeler element ( 30 , 31 ) activation means ( 42 ) and, the forward motion continuing, the user stops the activation of the drive means ( 60 ) when he detects a blockage of the advance, due to the fact that the feeler means ( 30 , 31 ) are positioned in the cavity. 
         [0048]    To ease the drive of the unit  10 , this one can be associated with a type of precursor rostrum  61  ( FIGS. 1 to 3 ) forming a guide, in the form of a cylindrical element of a limited diameter, joined to the catheter  60 . 
         [0049]    It will be noted that the implantation unit according to the invention can, first, be implanted alone, without implant or payload, the latter being implanted later on the implantation unit according to the same principle. In a similar case, the inventive unit comprises means for receiving the second support, to come, of the implant, said means being arranged to ensure the positioning and anchorage, both axially, by stopping, and radially, with angular error correction means such as a finger or cavity provided to fit with an element of matching shape in the second support. 
         [0050]    In the variant shown in  FIG. 7 , the implantation unit has the reference  110  and comprises functional elements similar to those of unit  10 , with the same references preceded by the hundred  1 , which have not however all been represented, with the aim of clarity. The cylindrical carrier element  120  is joined to a feeler element  131  which protrudes laterally and which has the same type of construction as the carrier element  120 . In precise fashion, the feeler element  131  appears in the form of a cylinder, stowed radially in the rest position. When the unit  110  is pushed by the catheter  160 , towards the bottom in  FIG. 7 , from a position above that shown, it engages in the coronary  52  when the free end is thus released from contact with the internal wall of the aorta  51 . 
         [0051]    The unit  110  thus comprises a type of fork that locks by stopping in the bifurcation between the aorta  51  and the coronary  52 . When the end position is reached the two cylindrical elements  120 ,  131  are deployed by two balloons respectively and form a type of two fingered glove. 
         [0052]    Thus, during the positioning phase, the feeler  131  presents a radially stowed form, thus with reduced diameter not risking blocking the coronary  52 . Then the feeler  131  is deployed, by inflation of the associated remote control balloon, and constitutes a lining, or internal ‘casing’, pressed against the internal wall of the coronary  52  in accordance with the principle explained above for the carrier cylinder  20 . 
         [0053]    It will be noted that, as  120  and  131  each occupy a particular branch  51 ,  52 , they can be considered as functionally equivalent, with the two principle functions if required. Each of them can in effect be a payload ( 2 ) carrier and can also be considered as being a feeler, because the aorta  51  can be considered (functionally in the context of the present invention) as being a cavity or branch with respect to the coronary  52 . Thus the feeler means comprise a cylindrical element  131  arranged to change from a stowed form to a radially deployed form, supported against a wall of the cavity, here the coronary  52 , under the influence of remote control means (balloon and catheter  160 ), 
         [0054]    To avoid the risks of movement of the feeler  131  into the coupling position to the coronary  52 , due to an angular error that necessitates several attempts, it can be arranged for a guide wire to be passed into the coronary  52  and the upper part of the aorta  51 , the unit  110  being threaded above it across the feeler  131  that is thus angularly oriented towards the coronary  52 . Another guide wire can at the same time guide cylinder  120  into the aorta  51 .