Abstract:
A method for positioning a centering introducer in a heart of a patient, which includes the steps of inserting an anchoring wire delivery catheter through a heart wall and to a treatment region of the heart, deploying at least one anchoring wire from the delivery catheter and into tissue in the treatment region of the heart, and removing the delivery catheter from the heart. A centering introducer can then be advanced along the anchoring wire to the treatment region, wherein the centering introducer includes an introducer element and at least one balloon. At least one of the balloons can then be inflated to reorient the introducer element in at least one direction relative to a longitudinal axis of the centering introducer.

Description:
TECHNICAL FIELD 
     The present invention relates generally to devices and methods for repair or replacement of heart valves, and more particularly to delivery systems and methods for accurately navigating to the area of the native mitral valve, such as for repairing the mitral valve area or for replacing a native mitral valve with a prosthetic heart valve. 
     BACKGROUND 
     One of the two atrio-ventricular valves in the heart is the mitral valve, which is located on the left side of the heart and which forms or defines a valve annulus and valve leaflets. The mitral valve is located between the left atrium and the left ventricle, and serves to direct oxygenated blood from the lungs through the left side of the heart and into the aorta for distribution to the body. As with other valves of the heart, the mitral valve is a passive structure in that it does not itself expend any energy and does not perform any active contractile function. 
     The mitral valve includes two moveable leaflets that open and close in response to differential pressures on either side of the valve. Ideally, the leaflets move apart from each other when the valve is in an open position, and meet or “coapt” when the valve is in a closed position. However, problems can develop with these valves, which can generally be classified as either stenosis, in which a valve does not open properly, or insufficiency (also called regurgitation), in which a valve does not close properly. Stenosis and insufficiency may occur independently or concomitantly in the same valve. The effects of valvular dysfunction vary, with mitral regurgitation or backflow typically having relatively severe physiological consequences to the patient. Regurgitation, along with other abnormalities of the mitral valve, can increase the workload placed on the heart. The severity of this increased stress on the heart and the patient, along with the ability of the heart to adapt to the increased stress, determine the treatment options that are available for a particular patient. In some cases, medication can be sufficient to treat the patient, which is the preferred option when it is viable; however, in many cases, defective valves have to be repaired or completely replaced in order for the heart to function normally. 
     One situation in which repair of a mitral valve can be viable is when the defects present in the valve are associated with dilation of the valve annulus, which not only prevents competence of the valve but also results in distortion of the normal shape of the valve orifice. Remodeling of the annulus is central to these types of reconstructive procedures to the mitral valve. When a mitral valve is repaired in this way, one common result is a reduction in the size of the posterior segment of the mitral valve annulus. As a part of the mitral valve repair, the involved segment of the annulus is diminished (i.e., constricted) so that the leaflets may coapt correctly on closing, and/or the annulus is stabilized to prevent post-operative dilatation from occurring. Either result is frequently achieved by the implantation of a prosthetic ring or band in the supra annular position. The purpose of the ring or band is to restrict, remodel and/or support the annulus to correct and/or prevent valvular insufficiency. Such repairs of the valve, when technically possible, can produce relatively good long-term results. 
     However, repair of the mitral valve area is sometimes either impossible or undesirable or has failed, such as in cases where dilation of the valve annulus is not the problem, leaving valve replacement as the preferred option for improving operation of the heart. In cases where the mitral valve is replaced, it can generally be replaced with either mechanical valves or bioprosthetic or tissue valves. The surgical procedure for implantation of many of these mechanical and tissue valves involves opening the patient&#39;s chest to access the mitral valve through the left atrium, and sewing the new valve in position. In order to simplify surgical procedures and reduce patient trauma, methods and devices have recently been developed for replacing the mitral valve using minimally invasive and/or percutaneous replacement techniques and devices. In one exemplary valve replacement procedure, a replacement valve can be delivered in a compressed condition to the native valve site, where it is expanded for implantation into the target site in a patient. With specific regard the replacement of the mitral valve, a replacement mitral valve can be inserted into a balloon catheter and delivered percutaneously via the vascular system to the annulus of the native mitral valve, where the replacement valve can be expanded by a balloon. 
     Due to the relatively complicated path through which a delivery system must travel to reach the area of the mitral valve for either its repair or replacement, many delivery systems that are currently available cannot provide for consistent navigation to the desired area. Thus, there is a continued desire to provide for improved mitral valve delivery systems and repair or replacement procedures that accommodate the physical structure of the heart without causing undue stress to the patient during the operation on the heart. 
     SUMMARY 
     In one aspect of this invention, a delivery system and method are provided for guiding an introducer tip, introducer element, and/or other components to desired locations in the area of the mitral valve, such as the annular region of the mitral valve. In one embodiment, the method is used to navigate a catheter to areas of the heart that are typically difficult to reach, such as areas that are only reachable via a path that includes one or more curves that have a tight radius. Such delivery systems and methods may be desirable for a number of reasons, such as to insert anchors for a mitral annulus reduction, to orient a replacement mitral valve in the area of the native mitral valve annulus, to insert a clip or other device during a mitral valve repair procedure, for example. 
     One exemplary delivery system of the invention includes two separate catheters. One of these catheters includes an anchoring wire and its delivery system, while the other of the catheters is used as a centering introducer. With this delivery system, a guidewire and at least one anchoring wire are delivered to a desired area of the heart with an anchoring wire delivery system, and then this delivery system and guidewire are removed from the patient, while the anchoring wire is attached to tissue of the patient and therefore remains in the patient. The anchoring wire is then used in a similar manner as a guidewire for engagement with a lumen of a centering introducer (i.e., to facilitate a desired positioning of the centering introducer relative to the heart of a patient). 
     In accordance with an embodiment of the invention, a method is provided for positioning a centering introducer in a heart of a patient. The method includes the steps of inserting an anchoring wire delivery catheter through a heart wall and to a treatment region of the heart, deploying at least one anchoring wire from the delivery catheter and into tissue in the treatment region of the heart, and removing the delivery catheter from the heart. A centering introducer can then be advanced along an anchoring wire to the treatment region, wherein the centering introducer comprises an introducer element and at least one balloon. At least one of the balloons can then be inflated to reorient the introducer element in at least one direction relative to a longitudinal axis of the centering introducer. The method may further include inserting a guidewire through the heart wall and to the treatment region of the heart, and then advancing the anchoring wire delivery catheter along the guidewire. According to one aspect of the invention, the treatment region of the heart is the annular region of a mitral valve. Once the centering introducer and its introducer element are positioned in a desired location a treatment device, such as a clip, an anchor, or a replacement heart valve can be introduced through the introducer lumen and introducer element and into the treatment region of the heart. 
     In accordance with an embodiment of the invention, a delivery system is provided for positioning an introducer element relative to a predetermined area of the heart. The delivery system includes an anchoring wire delivery catheter comprising a guidewire lumen and an anchoring wire lumen, an anchoring wire that is slideably engageable within the anchoring wire lumen, and a centering introducer comprising an introducer element and at least one balloon. The centering introducer can further include an anchoring wire lumen that is slideably engageable with the anchoring wire, and an inflation lumen operatively attached to the at least one balloon. The delivery system can further comprise a guidewire that is slideably engageable with the anchoring wire delivery catheter and which can be used to position the anchoring wire delivery catheter in a desired location relative to the patient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein: 
         FIG. 1  is a front view of an anchoring wire assembly of an exemplary embodiment of a delivery system of the invention; 
         FIG. 2  is a top view of the anchoring wire assembly illustrated in  FIG. 1 ; 
         FIG. 3  is an enlarged front view of a distal end portion of a delivery system, which includes an anchoring wire assembly of the type illustrated in  FIG. 1 , along with an extending guidewire; 
         FIG. 4  is a top view of the distal end portion of the delivery system illustrated in  FIG. 3 ; 
         FIG. 5  is a front view of a distal end portion of a delivery system of the type illustrated in  FIG. 3 , which illustrates the anchoring wire assembly in a retracted position with its needle tips exposed; 
         FIG. 6  is a top view of the distal end portion of the delivery system illustrated in  FIG. 5 ; 
         FIG. 7  is a front view of a distal end portion of a centering introducer and balloon in a deployed state; 
         FIG. 8 a    is a top view of the distal end portion of the centering introducer and balloon illustrated in  FIG. 7 ; 
         FIG. 8 b    is a cross-sectional view of a portion of the centering introducer taken along section line  1 - 1  of  FIG. 8   a;    
         FIG. 9  is a top view of the distal end portion of the centering introducer and balloon illustrated in  FIG. 8 , and further illustrating a portion of the tubing that is adjacent to the distal end portion; 
         FIGS. 10 through 16  are partial sectional perspective views of a heart as a delivery system is being guided, navigated, and deployed into the area of the native mitral valve; and 
         FIG. 17  is a perspective view of a centering introducer component of a delivery system in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the Figures, wherein the components are labeled with like numerals throughout the several Figures, and initially to  FIG. 1 , one exemplary configuration of a distal end portion of an embodiment of an anchoring wire assembly  10  of the invention is illustrated. Anchoring wire assembly  10  generally includes an anchor wire  12  attached by a crimp sleeve  14  to two anchor loops  16 ,  18 . The anchor loops  16 ,  18  may be fabricated of platinum, stainless steel, Nitinol, an alloy of the type commercially available under the trade designation MP35N, or other biocompatible metal. In one embodiment, the anchor loops  16 ,  18  are made of a shape memory material and formed into a loop or coil that that can be at least partially straightened or deformed by the application of a force, then can return generally to the loop or coil configuration when that force is removed or reduced. Each of the anchor loops  16 ,  18  includes its own respective distal tip  20 ,  22 , which can be relatively sharp for penetration into the tissue of a patient, as will be described below. 
     The anchor loops  16 ,  18  can be crimped or otherwise attached to the anchor wire  12  via the crimp sleeve  14 , which can be made of stainless steel, for example. The crimp sleeve  14  can initially be a generally tubular shaped portion that can optionally first be attached to the anchor wire  12  at its proximal end, such as by crimping, adhesives, or the like. The ends of the anchor loops  16 ,  18  that extend from the curved portion can then be inserted into the distal end of the crimp sleeve  14  by a desired amount, after which the crimp sleeve  14  can be compressed until it is sufficiently tight around the anchor wire  12  and anchor loops  16 ,  18  to securely attach the components to each other. Alternatively, the crimp sleeve  14  can be a separate component that is attached to the anchor wire  12  and anchor loops  16 ,  18  simultaneously, such as positioning a proximal end of the crimp sleeve over a distal end of the anchor wire  12 , inserting the wires of the anchor loops  16 ,  18  into the proximal end of the anchor wire  12 , then compressing the crimp sleeve  14  onto the anchor wire  12  and anchor loops  16 ,  18  with the use of a single crimping tool or other compression device(s). 
     In yet another alternative, the anchor loops  16 ,  18  are adhered within the crimp sleeve  14 , which may or may not also need to be compressed to further secure the components to each other. In yet another alternative, the anchor loops  16 ,  18  are attached to the anchor wire  12  without the use of a crimp sleeve  14 , such as by twisting the anchor loops onto the anchor wire  12  or by welding the anchor loops onto the end of the anchor wire  12 , for example. In yet another alternative, the anchor loops  16 ,  18  are integrally formed with the anchor wire  12  so that the loops  16 ,  18  are extensions from the distal end of the anchor wire  12 , rather than attachable components 
     Like the anchor loops  16 ,  18 , the anchor wire  12  may be fabricated of platinum, stainless steel, Nitinol, an alloy of the type commercially available under the trade designation MP35N, or other biocompatibie metal. In one embodiment, the anchor wire  12  is made of the same flexible wire material and assembly composition as that of a standard guidewire. The length of the wire  12  can vary, but is generally long enough to be able to extend outside the body of a patient when it is used for navigation into the patient and able to perform an exchange in accordance with the methods of the invention. 
     The anchoring wire assembly  10  is insertable into one lumen of an anchoring wire assembly delivery system, which consists of a multi-lumen catheter, such as a lumen  32  of a dual-lumen catheter  30  that is illustrated in  FIGS. 3 and 4 . As shown, anchor wire  12  is enclosed within the lumen  32 , with the anchor loops  16 ,  18  extending beyond a distal end of the catheter  30 . If the assembly  10  includes a crimp sleeve  14 , at least a portion of it can also extend beyond the distal end of the catheter  30  for full anchor deployment, or it can instead be enclosed within the lumen  32 . The catheter  30  further includes a second lumen  34 , in which a guidewire  36  is positioned. Guidewire  36  includes a distal end portion that extends beyond a distal end of the second lumen  34 . The catheter  30  of this embodiment is preferably made of a flexible material that can track relatively easily along the length of the guidewire  36 . It is understood that the catheter can further include one or more additional lumens for the insertion of other devices or components that can be used in accordance with the methods of the invention. 
     In order to prepare the catheter for insertion into a patient, the anchor wire  12  is pulled a proximal direction until the anchor loops  16 ,  18  are pressed against the distal end of the catheter  30 . The anchor wire  12  is then pulled even further in the proximal direction until the wires of the anchor loops  16 ,  18  begin to come uncoiled and are pulled into the lumen  32 . As shown in  FIGS. 5 and 6 , this movement of the anchor wire  12  relative to the distal end of catheter  30  can be continued until only the distal tips  20 ,  22  extend beyond the distal end of the catheter  30 . In order to prevent interference between these distal tips  20 ,  22  and any tissue within the patient, these tips  20 ,  22  can be retracted even further into the lumen  32  so that they do not extend beyond the end of the catheter  30 . The proximal end of the catheter  30  (not illustrated) can include a valve, such as a hemostasis valve, for both wires. A removable pin vise can be attached to the anchor wire  12  near the hemostasis valve to assist in the process of retracting the anchor wire  12  and its attached anchor loops  16 ,  18  and also in the deployment of these wires and loops. 
       FIGS. 7, 8   a , and  8   b  are front, top, and cross-sectional views, respectively, of an assembly that includes a centering introducer  50 , and  FIG. 17  is a perspective view of the centering introducer  50  separate from the other components of the assembly. Centering introducer generally includes a multi-lumen tube  52 , such as a tri-lumen tube, which can be at least somewhat flexible along its length. It is contemplated that different portions of the tube  52  can have different flexibilities along its length. When used in accordance with methods of the invention that will be described in further detail below, the dual-lumen catheter  30  and guidewire  36  described above are removed from a patient to leave the anchor wire  12  secured within the patient, such that the multi-lumen tube  52  can then be guided along the anchoring wire  12  to position it in a desired location within a patient. 
     Centering introducer  50  includes a first lumen  54  of the tube  52  that extends along the tube length and which is positionable over the anchoring wire. Tube  52  also includes a second lumen  56  that extends along the tube length, but is plugged at its distal tip  58  and includes a notched area  60  that is open for communication with the inside of a balloon  62 . Tube  52  further includes a third lumen  63  that extends through its length and then branches off from the main body of the centering introducer  50  adjacent to the balloon  62 . This third lumen  63  may also be referred to as an introducer lumen, which can be used for helping to guide an end effector or introducer element  64  that extends from this lumen  63  and to a specific location, as will be described in further detail below. 
     The balloon  62  can be provided with a number of different shapes when it is expanded, such as the diamond-like shape illustrated in  FIGS. 7 and 8 , although it is understood that a number of different external shapes for the balloon can be used. When the device is inserted into a patient, the balloon will be unexpanded so that it is has a minimal profile size. However, after the device is located in a desired position within a patient, the balloon will be expanded in such a way that it will push the introducer element  64  away from the anchor wire  12 . Thus, the size and shape of the balloon  62  can be designed or selected to provide a desired deflection of the introducer element when the balloon is inflated. The proximal end of the centering introducer (not illustrated) can include a handle that includes a valve (e.g., a small hemostasis valve) for the anchoring wire, a valve (e.g., a large hemostasis valve) for any device that is guided through the introducer lumen, and/or a port  68  for injection of saline or air into the lumen that is used to inflate the balloon. 
     The system may further include a separate flexible tube or sheath  66  that is positionable over the multi-lumen tube  52 . The inside diameter of the sheath  66  is at least slightly larger than the outer diameter of the multi-lumen tube  52  so that it can move along the length of the tube  52 . The sheath  66  can further be configured so that when it is moved toward the distal end of the delivery system, it can fully encase both the introducer element  64  and the balloon  62  (when the balloon is in its uninflated or semi-inflated condition). 
       FIG. 9  illustrates an embodiment of the delivery system of the invention that includes a multi-lumen tube  52  that has a pre-set curve. The curve can provide the advantage of retaining the position of keeping the introducer element in a desired position relative to the balloon. The curve of this figure is only illustrative, and it is contemplated that the pre-set curve may have a larger or smaller radius than shown and/or the tube can include multiple sections that have different curves. For example, adjacent sections or lengths of the tube can have different radii of curvature in order to accommodate different patient anatomies. In addition, different curves can be attained with the use of a steerable catheter. It is further contemplated that the tubing can be at least slightly twisted along its length, such as to cause the introducer element to be able to track in a perpendicular direction to the distal tip when it is being inserted into a patient. In addition, it is contemplated that the tube can be sufficiently stiff so that it generally retains its shape when being inserted into a patient, but can also have enough flexibility so that it can be reconfigured prior to insertion of the delivery system into a patient, if desired. 
       FIGS. 10 through 16  are partial sectional perspective views of a heart  100  with an embodiment of the delivery system of the invention as it can be guided, navigated, and deployed into the area of the native mitral valve. In particular,  FIG. 10  illustrates a number of components of heart  100 , including the left atrium  102 , the mitral valve  104 , the left ventricle  106 , the right ventricle  108 , the right atrium  110 , the fossa ovalis  112 , the inferior vena cava (IVC)  114 , and the right pulmonary veins  116 . The mitral valve  104  further includes an area that is commonly referred to as the A1-P1 commissure, which is generally designated with reference number  118 . This nomenclature for the mitral valve is derived from its two primary leaflets, which are referred to as the anterior and posterior leaflets, each of which is further broken down into scallops or regions divided by commissures, or zones of apposition. Three regions are found on the anterior leaflet (A1 through A3) with opposing regions on the posterior leaflet (P1 through P3). The mitral valve  104  further includes multiple chordae  120  attaching to the anterior and posterior papillary muscles of the left ventricle  106 . 
     A delivery system of the invention can be guided to the area of the mitral valve in a number of ways, one of which includes accessing the right atrium  110  through the femoral vein, while a trans-septal puncture would be used to gain access to the left atrium  102 . A guidewire  130  can then be advanced into the left ventricle  106 . In most cases, this guidewire  130  will naturally track into the A1-P1 commissure region  118 , as is illustrated in  FIG. 10 . The stiffness of the guidewire  130  can be chosen or designed to provide for ease of tracking to the desired area, where a guidewire that is too flexible may have difficulty reaching the desired target area of the heart, such cases, it may be desirable to instead use a guidewire with a higher stiffness in order to increase the likelihood that the guidewire will more easily reach its desired location in the heart. 
     After the guide wire  130  is positioned in its desired location, a distal tip of an anchoring wire delivery catheter  132  can be guided forward over the guidewire  130  to the A1-P1 commissure region  118 , as is illustrated in  FIG. 11 . The distal tip can be pressed against the annulus in the A1-P1 commissure region  118  as it is being monitored, such as can be accomplished using echo and/or tactile feedback. An anchor wire  134 , which is located within the delivery catheter  132 , can then be pushed forward to deploy the anchor into the annular tissue. In order to be sure the anchor is securely attached to the tissue, the user can pull the wire with slight to moderate tension in a direction that is opposite the deployment direction. Once the anchor wire is in place, the delivery catheter  132  can be removed, leaving only the anchor wire  134  in the patient, as is illustrated in  FIG. 12 . 
       FIG. 13  illustrates a subsequent step in the delivery process, in which a centering introducer  140  is advanced over the anchor wire  134  and into the A1-P1 commissure region  118 . At this point, a sheath  142  can be moved proximally to expose a balloon  144  and an introducer element  146  that can extend at an angle relative to the body of the delivery, system, as is illustrated in  FIG. 14 . Although a single balloon is illustrated in this embodiment, it is contemplated that the centering introducer may instead include multiple balloons, which may optionally each include their own inflation controls. 
     Referring now to  FIG. 15 , after the introducer element  146  and balloon  144  are in their desired locations in the patient, the balloon  144  can be inflated, which will contact and displace the introducer element  146 . In one exemplary embodiment, inflation of the balloon  144  causes the introducer element  146  to travel across the mitral valve from the A1-P1 commissure region  118 , where it was originally positioned, and toward another region of the native mitral valve (e.g., the A3-P3 commissure region). Displacement of the introducer element  146  can be controlled by monitoring and controlling the inflation of the balloon  144  and the corresponding amount of interference between the balloon  144  and the introducer element  146 . Thus, different levels of balloon inflation will provide for access to different areas of the leaflets. In addition, the balloon can be designed and used in such a way the balloon  144  can also push off of the atrial wall, which can provide additional leverage for positioning the delivery system. 
     In cases where it is desired to obtain additional repositioning of the delivery system when it is in a patient, the proximal end or handle area of the delivery system can be rotated, as is illustrated in  FIG. 16 . Such a rotation of the system can allow the introducer element  146  to move across the valve and toward one of the annular regions. In order to achieve additional adjustability for the delivery system, tension can be applied to the anchor wire, and/or the entire catheter can be pushed or pulled, if desired. 
     After the centering introducer is positioned in its desired location relative to the native mitral valve, one or more procedures can be performed within the adjacent area of the heart. In such procedures, devices and instruments can be moved into the desired area of the heart via the introducer lumen and introducer element. For example, anchors can be inserted for a mitral valve annulus reduction or reshaping, a replacement mitral valve can be deployed and/or oriented, one or more clips can be inserted for mitral repair, and/or the like. For another example, the therapy delivery catheter can be inserted and advanced prior to navigation. In any case, when all of the desired procedures are completed, the delivery system can be removed from the patient. This may be accomplished by deflating the balloon, sliding the sheath toward the distal end of the delivery system to recapture the balloon and introducer element. In addition, the anchor wires can be pulled in a proximal direction until they are released from the mitral valve annulus area. The delivery system can then be removed from the heart of the patient. 
     The present invention has now been described with reference to several embodiments thereof. The entire disclosure of any patent or patent application identified herein is hereby incorporated by reference. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the structures described herein, but only by the structures described by the language of the claims and the equivalents of those structures.