Abstract:
Inflatable heart valve implants and methods utilizing those valves designed to reduce or eliminate the regurgitant jet associated with an incompetent atrioventricular valve. The heart valve implants, which are deployed via a transcatheter venous approach, comprise an inflatable balloon portion movably connected to an anchored guide shaft and movable from a distal position in the ventricle to a more proximal position between leaflets of a native atrioventricular valve. The range of movement of the inflatable valve body can be adjusted in situ after or before the guide shaft has been anchored to native heart tissue during surgery.

Description:
RELATED APPLICATION 
     This application claims priority on U.S. provisional patent application Ser. No. 61/820,601 filed May 7, 2013. 
    
    
     The present invention is directed to inflatable heart valve implants and methods utilizing those valves designed to reduce or eliminate the regurgitant jet associated with an incompetent atrioventricular valve. The embodiments comprise devices and methods wherein, via a transcatheter venous approach, an inflatable balloon portion is movably disposed along an anchored guide shaft from a distal position in the ventricle to a more proximal position between leaflets of a native atrioventricular valve. 
     BACKGROUND 
     Some previously known methods of treating incompetent, i.e. leaking, atrioventricular valves comprise the steps of removing the patient&#39;s native valve leaflets and replacing them with an artificial valve. Some artificial valves, particularly those which are designed to be substantially stationery or fixed relative to the valve annulus, can create a substantial risk of stenosis or obstruction to the desired flow of blood into the ventricle. 
     SUMMARY 
     The various embodiments of the present invention comprise methods and devices for treating an incompetent atrioventricular heart valve without removing the existing valve leaflets and in a manner which does not create a substantial obstruction to the inflow of blood through the valve during the diastolic portion of the cardiac cycle. 
     The valve devices are inflatable transcatheter intracardiac devices designed for placement within an incompetent native atrioventricular valve apparatus (i.e. mitral or tricuspid). As used herein, the term “native” is meant to indicate that the original leaflets of the atrioventricular valve have not been removed. The disclosed valve devices reduce or eliminate the regurgitant jet associated with the incompetent valve with an inflatable balloon which is movably positioned relative to, and preferably on, a guide shaft anchored to the heart wall. The inflated balloon portion occupies the regurgitant valve orifice and coapts with the native leaflets to create a better seal during the systolic portion of the cardiac cycle. The inflated balloon portion is then moved distally into the ventricle by the inflow of blood during the diastolic portion of the cardiac cycle to minimize the obstruction of blood flowing into the ventricle. Some embodiments comprise adjustable attachments between the guide shaft and range limiting structures which limit the range of proximal and distal movement of the balloon portion relative to the guide shaft and discernible indicia to assist the surgeon with proper placement of the valve device during surgery. Thus, while the heart valve implant is initially provided such that the balloon has some predetermined range of movement relative to the guide shaft, that range of movement can be changed, i.e. adjusted. As used herein, the term “predetermined” is not used to indicate that a given range of movement is permanent. 
     The methods comprise the steps of anchoring one of the valve devices to a heart wall and inflating the movable balloon portion. Some methods also comprise the steps of radiographically observing the range of motion of the inflated balloon on the guide shaft via fluoroscopy and transesophageal echocardiography and adjusting the positioning of at least one of the range limiting structures which limit the extent of movement of the balloon in order to properly position the inflated balloon for optimal sealing and blood flow. As used herein, the terms “balloon” and “inflatable valve body” are used interchangeably. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial view of a first valve device of the present invention. 
         FIG. 2  illustrates a first valve device of the present invention with the balloon inflated and in the proximal position. 
         FIG. 3  illustrates a valve device of  FIG. 1  with the balloon inflated and in the distal position. 
         FIG. 4  is a view of a valve device of  FIG. 1  shown in a heart during the systolic portion of the heart cycle. 
         FIG. 5  is a view of a valve device of  FIG. 1  shown in a heart during the diastolic portion of the heart cycle. 
         FIG. 6  is a partial, cross-sectional view of a range limiting structure of the present invention. 
         FIG. 7  is a partial, cross-sectional view of an alternative range limiting structure of the present invention. 
         FIG. 8  is a perspective view of the valve device of  FIG. 1 . 
         FIG. 9  is a partial view of a valve device of a second embodiment of the present invention. 
         FIG. 10  illustrates the valve device of  FIG. 9  with the balloon inflated and in the proximal position. 
         FIG. 11  illustrates a valve device of  FIG. 9  with the balloon inflated and in the distal position. 
         FIG. 12  is a view of a valve device of  FIG. 9  shown in a heart during the systolic portion of the heart cycle. 
         FIG. 13  is a view of a valve device of  FIG. 9  shown in a heart during the diastolic portion of the heart cycle. 
         FIG. 14  is a perspective view of the valve device of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     One valve device of the present invention comprises a flexible shaft which may have an outer layer of polyurethane or a silicon rubber coating with an active fixation distal end. With reference to  FIG. 1  which is a partial view of a first embodiment with elements removed for clarity, a guide shaft  10  comprises an anchor  12  at its distal end. Anchor  12  is generally in the form of a spiral screw and is adapted to be secured to a heart wall by rotating the internal portion of the shaft during transcatheter placement. Anchor  12  can be integrally formed with shaft  10  or separately formed and connected proximate the distal end of shaft  10 . An inflatable balloon  20  is movably positioned relative to shaft  10  within a range of motion described below. Balloon  20  is preferably mounted on shaft  10 . The balloon is also preferably tapered on both ends to promote laminar blood flow around the balloon thereby decreasing the likelihood of thrombogenesis. 
     An inflation lumen  22  is used for inflating and deflating the balloon. The inflation lumen extends to a point outside the surgical site for access by the surgeon. In one embodiment, the inflation lumen is detachable from the balloon after inflation. In this embodiment, the device is then self-contained within the heart. This decreases the risk of thrombosis. In another embodiment, the inflation lumen is not detachable thereby facilitating deflation of the balloon for subsequent removal. 
     All components are formed of suitable materials. Balloon  20  is preferably formed of ePTFE but can be formed of other materials known in the art, such as polypropylene. Balloon  20  also preferably comprises markers  24 , e.g. metal tags, (illustrated in dashed lines in the figures) implanted in distal and proximal portions of the balloon to permit a surgeon to observe the balloon&#39;s position and range of motion via fluoroscopy. 
     The range of motion of balloon  20  along shaft  10  is limited in both the proximal and distal directions by range limiting structure. With reference to  FIGS. 2 and 3 , this embodiment comprises a ring  30 , sometimes referred to herein as a pseudo-annulus ring  30 . The internal opening of the ring  30  is smaller than the outer diameter of the inflated balloon  20  so that the inflated balloon  20  cannot pass through ring  30 . Ring  30  is connected to a proximal portion of the shaft  10  by a plurality of proximal artificial chordae tendineae  33 . The ring  30  is also connected to a more distal portion of the shaft  10  by a plurality of distal artificial chordae tendineae  36 . In preferred embodiments, the distal artificial chordae tendineae  36  are connected to shaft  10  at a position which is spaced from the distal end of shaft  10 . Preferably, when measured from the location where the proximal artificial chordae tendineae are connected to the shaft  10 , the distal artificial chordae tendineae are connected to the shaft at a location spaced by a distance of less than 80% of the distance between the connection of the proximal artificial chordae tendineae to the shaft  10  and the distal end of shaft  10 , more preferably less than 50% of this distance, and most preferably about one-third of this distance. Movement of the balloon is preferably restricted to the proximal third of the ventricle after the valve device has been implanted. By avoiding excessive motion of the balloon, the risk of trauma to the heart wall by the moving balloon is minimized. In this embodiment, all of the artificial chordae tendineae are secured to shaft  10 . The ring  30  is preferably positioned slightly proximally of the atrioventricular annulus. 
     As shown in  FIG. 2 , the proximal movement of the balloon  20  is limited by the length of the distal artificial chordae tendineae which extend from the shaft  10 , pass around the balloon  20 , and then to ring  30 . Balloon  20  is moved to this proximal position illustrated in  FIG. 2  during the systolic portion of the cardiac cycle. In this configuration, the proximal artificial chordae tendineae  33  are unloaded, i.e. not under load, or slack as shown in  FIG. 2 . 
     As shown in  FIG. 3 , the distal range of motion of balloon  20  is constrained by the distal artificial chordae tendineae  36  which are attached at their proximal ends to the ring  30  whose distal movement is constrained by the length of the proximal artificial chordae tendineae  33 . As balloon  20  moves distally at the beginning of the diastolic portion of the cardiac cycle, the proximal artificial chordae tendineae  33  become taut, thereby limiting the distal movement of ring  30 . The balloon  20  will move distally until the tautness of the distal artificial chordae tendineae  36  arrests the further distal movement of the balloon  20 . The artificial chordae tendineae  33 ,  36  of this embodiment and the pseudo-annulus ring  30  are also preferably formed of flexible ePTFE suture material, or other biocompatible filaments commonly used for sutures within the heart and blood vessels. The inherent properties of the artificial chordae tendineae and the pseudo-annulus ring provide for the progressive deceleration of the balloon which provides for the gradual closure of the valve which mimics the normal motion of a healthy, native valve apparatus during the cardiac cycle. 
       FIGS. 4 and 5  illustrate the embodiment shown in  FIGS. 1-3  installed in a right ventricle  50  with the balloon  20  inflated.  FIGS. 4 and 5  are not meant to be exact representations of an actual heart, but suffice to illustrate the positioning of the valve device relative to the leaflets  55  whose proximal movement are normally limited by the patient&#39;s native chordae tendineae  57 . The artificial chordae tendineae  33 ,  36  are omitted from  FIGS. 4 and 5  for clarity. In  FIG. 4 , the inflated balloon  20  is in its proximal position between atrioventricular leaflets  55  which separate the ventricle  50  from the atria  60 . In the position shown in  FIG. 4 , the proximal end of balloon  20  is just distal of the patient&#39;s tricuspid annulus.  FIG. 5  illustrates an example of the position of balloon  20  during the diastolic phase during which the balloon  20  moves distally to allow ventricular filling without obstructing the inflow of blood into the ventricle or creating a stenosis. 
     It will be appreciated that different patients, whether human or other mammals such as dogs, have different size hearts. In order to obtain the proper positioning of the inflated balloon, proper sealing and other functionality such as not creating undue obstruction to blood flow, when using the embodiment shown in  FIGS. 1-6 and 8 , it is necessary to use different sized valve devices, for example having shafts of different lengths and different size balloons. 
     According to other embodiments, the points of attachment of the artificial chordae tendineae to the guide shaft are adjustable. This allows a surgeon to change and fine tune the range of motion of the balloon relative to the guide shaft in situ after or before the guide shaft has been anchored in place. Of course, the adjustment can also be made outside of the patient&#39;s body. 
     With reference to  FIG. 6  which is a partial view of a further embodiment, the artificial chordae tendineae  36  are fixed to a ring  35  which has a selectively adjustable fit with guide shaft  10  which prevents movement relative to shaft  10  under conditions normally encountered in a heart, but can be repositioned with suitable surgical instruments. In other words, ring  35  is sized to fit very snuggly on shaft  10  and will not normally move relative to shaft  10  during the cardiac cycle, but can be purposely repositioned by a surgeon during surgery to adjust the range of movement of the balloon relative to the shaft. 
       FIG. 7  illustrates a still further embodiment wherein guide shaft  110  is provided with a plurality of grooves  115  which partially receive a ring  135 . In this embodiment, the artificial chordae tendineae  36  are fixed to ring  135 , and ring  135  is sized to fit very snuggly within grooves  115  on shaft  110  and will not move relative to shaft  10  except when ring  135  is purposely repositioned by a surgeon during surgery. 
     While rings  35  and  135  and guide shaft  110  have been described and illustrated with the distal artificial chordae tendineae, similar proximal rings  35 ′ and  135 ′ are provided when desired for adjustably connecting the proximal artificial chordae tendineae to the guide shaft. Rings  35 ,  135  can be formed of suitable biocompatible polymeric or rubber-like materials. 
       FIG. 8  is a perspective view of the heart valve implant shown in  FIGS. 2 and 3 . 
       FIGS. 9-14  correspond to the views shown in  FIGS. 1-5 and 8  and illustrate a preferred embodiment of the present invention wherein the heart valve implant comprises an inflatable valve body with more tapered proximal and distal ends. The heart valve implant of this embodiment comprises a guide shaft  210 , anchor  212 , inflatable valve body  220  comprising markers  224 , inflation lumen  222 , proximal artificial chordae tendinae  233  connected to pseudo annulus ring  230  and distal artificial chordae tendinae  236 . This embodiment is deployed in the same manner as the embodiment shown in  FIGS. 1-6 and 8 . 
     During surgery, the valve comprising a deflated balloon is inserted through a delivery device, such as a guiding catheter, and the distal end of the valve device is fixed, preferably into the apex of the related ventricle via active fixation corkscrew mechanism  12 . Once the device is fixed in position, the occluder balloon  20  is inflated via inflation lumen  22  with a mixture of saline and iodinated contrast material or an injectable polymer. The valve device is observed by the surgeon via fluoroscopy and positioned so that balloon  20  sits between the leaflets of the native atrioventricular valve leaflets during the systolic portion of the cardiac cycle. This positioning of the valve occludes blood from regurgitating back into the atria. At the beginning of the diastolic portion of the cardiac cycle the balloon moves into the ventricle allowing for ventricular filling without creating a stenosis or obstruction to inflow. According to certain methods, the surgeon also performs the step of moving one or more of the attachment rings  35 ,  35 ′ relative to the guide shaft in order to adjust the range of movement of the inflatable valve body relative to the guide shaft. The entire guide shaft and/or the inflation lumen, including the injection port for the inflation lumen, can remain attached to the patient or can be detached at some desired point proximal to the attachment site, e.g. attachment ring  35 ′, of the proximal artificial chordae tendineae. 
     The embodiments of the present invention offer several significant advantages. Since they are balloon based, they have a low profile. If desired, the illustrated embodiments can be inserted through narrow blood vessels via a transcatheter venous approach with an 8 French catheter. Many other devices require 18-24 French delivery catheters which can significantly limit vascular access. The sealing function of the presently described devices relies, in part, on the native structure of the atrioventricular valve so this native structure of the patient&#39;s heart is not required to be removed for deployment of the disclosed devices. This reduces the time of surgery and discomfort to the patient. The present valves also rely upon the use of less hardware in the heart when compared to some previously known artificial valves. The movability of the balloon relative to the guide shaft advantageously minimizes the obstruction to blood flow. The preferred tapered configuration of the proximal and distal portions of the inflatable valve body promotes laminar blood flow around the balloon thereby decreasing the likelihood of thrombogenesis. The adjustability of the attachment sites between the artificial chordae tendineae and the guide shaft allows for adjustments to the range of movement of the balloon relative to the guide shaft to be made during deployment to maximize the reduction of the regurgitant jet. The device is deployed via a transcatheter venous method and as a result is much less invasive than traditional open heart surgery and does not require cardiopulmonary bypass. Unlike many known heart valve implants, embodiments of the present invention are retrievable from the patient.