Abstract:
A device and method for treatment of atrioventricular regurgitation comprises a suturing device. The suturing device is configured to be introducible, via blood vessels leading to the heart, to two leaflets of the atrioventricular valve between the atrium and a corresponding ventricle of the heart. The suturing device is configured for binding together the two leaflets along the free edges of the leaflets. A method of using the device includes inserting the suturing device into a catheter, introducing the catheter to the heart and positioning a distal end of the catheter close to two leaflets of an atrioventricular valve, capturing the free edges of the two leaflets with the suturing device in its open state, binding together the two leaflets by transition of the suturing device into its closed state, and retracting the catheter from the heart. As a result, the closing of the valve is improved.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 10/383,596, filed Mar. 10, 2003 under the same title, now U.S. Pat. No. 7,011,669, which is a continuation of U.S. application Ser. No. 09/670,082, filed Sep. 26, 2000 under the same title, now U.S. Pat. No. 6,719,767. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a device for treatment of atrioventricular regurgitation and a method for treatment of atrioventricular regurgitation using said device. 
     The heart has two atrioventricular valves, the mitral valve, which is situated between the left atrium and the left ventricle, and the tricuspid valve situated between the right atrium and the right ventricle. The tricuspid valve has three leaflets, two of which are much bigger than the third. These two bigger leaflets could be considered to correspond to the two leaflets of the mitral valve. Therefore, only the mitral valve will hereinafter be discussed although corresponding discussions could apply to the tricuspid valve. 
     Mitral regurgitation is the medical name of a problem that occurs in the heart. A person that suffers from mitral regurgitation has a mitral insufficiency, i.e. the mitral valve between the left atrium and the left ventricle cannot close entirely. Thus, when the ventricle is contracted in order to pump out blood through the aorta, some blood leaks back into the atrium instead. This will lead to a reduced functionality of the left ventricle and subsequently to heart insufficiency, which is a mortal disease. 
     Mitral insufficiency can result from, for example, ischemic disease, degenerative disease of the mitral apparatus, rheumatic fever, endocarditis, congenital heart disease and cardiomyopathy. The four major structural components of the mitral valve are the annulus, the two leaflets, the chordae and the papillary muscles. Any one or all of these in different combinations may be injured and create insufficiency. 
     At present mitral regurgitation is treated by open-heart surgery. This is a major operation and requires the use of total cardiopulmonary by-pass, aortic cross clamping and cardioplegic arrest. To certain groups of patients this is particularly hazardous and there is an apparent risk of not surviving the operation. 
     The treatment consists of either mitral valve replacement or repair. Replacement can be performed with either mechanical or biological valves. 
     The mechanical valve carries the risk of thromboembolism and requires anticoagulation, with all its potential hazards, whereas biological prostheses suffer from limited durability. Another hazard in connection with replacement is the risk of endocarditis. These risks and other valve related complications are greatly diminished with valve repair. 
     The four basic techniques of repair include the use of an annuloplasty ring, quadrangular segmental resection of diseased posterior leaflet, shortening of elongated chordae, and transposition of posterior leaflet chordae to the anterior leaflet. The techniques of mitral valve repair rely on decreasing valve area to increase leaflet apposition, but fail to address subvalvular dysfunction. Mitral insufficiency caused by prolapse of the anterior leaflet, posterior leaflet with calcified annulus, or prolapse of both leaflets constitutes a more demanding challenge to repair. 
     In 1995 Alfieri et al introduced modifications in the operative technique that allow a more expeditious and reproducible procedure than the traditional of greater complexity. This is achieved by simply anchoring the prolapsing free edge of the leaflet to the facing edge of the other leaflet (edge-to-edge technique), thus creating a double orifice of the mitral valve. The hemodynamic behavior of a double orifice mitral valve does not differ from that of a physiological valve of the same total area. Pressure drops and flow velocity across the valve are not influenced by the configuration of the valve. 
     Some efficient methods of treating mitral insufficiency exist as shown above, but all of them require open-heart surgery. Since many patients with mitral regurgitation are elderly or have a poor left ventricular function, they would benefit from a less invasive procedure that does not involve the use of cardiopulmonary by-pass as required by conventional techniques. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a device and a method for treatment of atrioventricular regurgitation that will be applicable to a beating heart. 
     Thus, a device for treatment of atrioventricular regurgitation comprises a suturing means having such dimensions as to be introducible, via blood vessels leading to the heart, to two leaflets of an atrioventricular valve between an atrium and a corresponding ventricle of the heart and being designed for binding together the two leaflets in a position along the free edges of the leaflets, whereby the closing of the atrioventricular valve is improved. 
     Preferably, the atrioventricular valve is the mitral valve between the left atrium and the left ventricle of the heart. 
     Diseases to the atrioventricular valves are much more common in the mitral valve than in the tricuspid valve. Therefore the focus of the invention is on the treatment of the mitral valve although treatment of the tricuspid valve could work equally well using the device. 
     The suturing means is preferably transitional between two states, being open in a first state and substantially closed in a second state. 
     This makes the suturing means capable of reaching the free edges of the mitral leaflets in the first state and of bringing them closer to each other when transitioned into the second state. 
     In a preferred embodiment, the suturing means comprises a clip. 
     Preferably, the clip has two arms pivotally connected to each other at a first end thereof, the arms forming a V in the first state of the clip and being substantially parallel in the second state of the clip. 
     Consequently, the arms of the clip can capture both mitral leaflets in the first state and bring them closer together in the second state. 
     Desirably, the arms of the clip have second, free ends bent towards each other so that these ends of the arms in the second state of the clip are brought proximal to each other. 
     This means that the mitral leaflets can be brought in close proximity to create a suture as the ends of the arms capturing the mitral leaflets in the second state of the clip are brought proximal to each other. 
     Further, each second end of the arms is preferably sharp. 
     As a result, the clip can easily capture the mitral leaflets and are capable of gripping the leaflets between its arms. 
     Suitably, the clip has two pairs of arms connected to each other by two crossbars near the connected first ends of the arms. 
     This means that the clip can get a good and lasting grip on the mitral leaflets. 
     Preferably, the device comprises a catheter for introduction of the clip via the blood vessels into the heart, said catheter having an outermost sheet covering the clip and being retractable therefrom. 
     This allows the clip to easily be introduced into the heart and there be uncovered for application to the mitral valve. 
     In one embodiment the catheter has a rod for holding the clip substantially in the open state within the outermost sheet and an applicator for pushing the clip off the rod for transition thereof into the closed state when the outermost sheet is retracted from the clip. 
     This is desirable for the application of the suturing means, as the transition between the two states of the suturing means can be controlled for capturing and suturing of the mitral leaflets. 
     In another embodiment the catheter has a rod for holding the clip substantially in the open state within the outermost sheet, said rod also having a puncturing means at a distal tip thereof. 
     This means that the catheter can be introduced via a vein since the puncturing means can be used to puncture the interatrial septum so as to enable the device to be brought into the left atrium from the right atrium. 
     Preferably, the suturing means consists of a memory material such as Nitinol. 
     As a result, the suturing means can easily be made to transform from its first state to its second and thereafter maintain its second state. 
     According to the present invention, the method for treatment of atrioventricular regurgitation comprises the steps of providing a suturing means having an open state and a closed state; inserting the suturing means into the distal end of a catheter; introducing the catheter via blood vessels leading to the heart, so as to position the distal end of the catheter close to the free edges of two leaflets of an atrioventricular valve between an atrium and a corresponding ventricle of the heart; capturing the free edges of the two leaflets with the suturing means in its open state; binding together the two leaflets by transition of the suturing means into its closed state; and retracting the catheter from the heart while leaving the suturing means fixed on the two leaflets. 
     Preferably, the atrioventricular valve is the mitral valve between the left atrium and the left ventricle. 
     Preferably, the suturing means is covered with a protective sheet of the catheter when introduced into the distal end thereof and uncovered by retraction of the protective sheet when positioned close to the free edges of the two leaflets of the atrioventricular valve. 
     Consequently, the suturing means can be introduced into the heart in a convenient way and be exposed in the ventricle. 
     In a mitral valve embodiment of the invention the catheter is introduced into the brachial or femoral artery and is passed retrograde to the blood flow through the aorta to the left ventricle. 
     In another mitral valve embodiment the catheter is introduced into a vein and passed up to the heart via the vein. The catheter could be introduced through any suitable vein, such as the femoral, jugular or subclavian veins. In this embodiment, the catheter preferably has a puncturing means on a distal tip thereof, such that the interatrial septum may be punctured by said puncturing means and the catheter be introduced through the septum to the left atrium and then passed to the left ventricle. 
     This means that the catheter may be introduced through the femoral vein since a passage from the right side of the heart to the left side is achievable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood by means of the following description of preferred embodiments referring to the accompanying drawings, in which 
         FIG. 1  is a partially sectional view of a heart having a suturing means applied on the mitral valve according to the present invention; 
         FIG. 2  is a perspective view of a suturing means according to the present invention; 
         FIG. 3  is a sectional view of a catheter carrying a suturing means according to one embodiment of the invention; 
         FIG. 4  is a perspective view of the catheter in  FIG. 3  carrying a suturing means that has been unsheathed; 
         FIG. 5  shows schematically how a device according to the invention can be inserted through an artery into the left ventricle of the heart; 
         FIG. 6  is a sectional view of a catheter carrying a suturing means according to another embodiment of the present invention; 
         FIG. 7  is a perspective view of the catheter in  FIG. 6  carrying a suturing means that has been unsheathed according to another embodiment of the invention; and 
         FIG. 8  shows schematically how a device according to the invention can be inserted through a vein into the left ventricle of the heart. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The device will now be described with reference to its use on a mitral valve. However, it is obvious that the device could also be used on the two biggest leaflets of the tricuspid valve. 
       FIG. 1  shows a heart  1 . The left side of the heart  1  is shown in section. A clip constituting a suturing means  2  is applied to the free edges of the mitral valve  3  keeping the mitral leaflets  4 ,  5  together in a connection point so as to create a double orifice, one orifice on each side of the connection point, thus allowing the leaflets  4 ,  5  to close completely. 
     In the following there will be described a device and a method for creating a double orifice in the mitral valve  3  of a beating heart  1 . 
     Referring now to  FIG. 2 , an enlargement of the suturing means  2  is showed. The suturing means  2  being a clip consists of two pairs  6 ,  7  of arms  8 - 9  and  10 - 11 . The arms  8 - 9  and  10 - 11  in the pairs are connected in one end  14 ,  15  and thus are formed in one piece. In their other end the arms  8 - 9  and  10 - 11  are bent towards each other in a bent portion  16 . The bent portions  16  are terminated with a sharp tip  17  so as to be able to engage and grab the mitral leaflets  4 ,  5 . 
     The clip  2  has two parallel crossbars  12 ,  13  that each connect one arm  8 ,  9  in one pair  6  to one arm  10 ,  11  in the other pair  7 . The crossbars  12 ,  13  are equally long and are connected to the arms  8 - 9  and  10 - 11  at equal distance from the connections  14 ,  15 . The pairs  6 ,  7  of arms are thus kept parallel by the crossbars  12 ,  13 . The crossbars  12 ,  13  are attached to the arms  8 - 9  and  10 - 11  near the connection ends  14 ,  15 . 
     The clip  2  is made of a memory metal, such as Nitinol, and in  FIG. 2  it is shown in a second state where the arms  8 - 9  and  10 - 11  in the pairs are parallel and the bent portions  16  in their ends are brought in close proximity to each other. The memory material of the clip  2  biases the clip  2  towards its second, closed state. In a first state, the arms  8 - 9  and  10 - 11  in the pairs are opened, forming a V, as the angle in their connections  14 ,  15  is increased. The clip  2  is capable of grasping the mitral leaflets  4 ,  5  at their free edges and bind the edges together by capturing the leaflets  4 ,  5  in the first state of the clip  2  and keeping them together in the second state of the clip  2 , where the arms are closed and parallel. 
     The clip  2  is inserted into a beating heart  1  by using a catheter. Referring to  FIGS. 3 and 4 , a first embodiment of a catheter  18  will be described. In its innermost part the catheter  18  has a supportive rod  19  that is slidable in a hollow applicator  20 . In its outermost part the catheter  18  has a protective sheet  21  that also is slidable upon the applicator  20 . 
     The clip  2  is attached in a distal end of the catheter to the applicator  20 . The attachment is made in the connections  14 ,  15  of the arms  8 - 9  and  10 - 11  in the pairs. The supportive rod  19  can be extended out of the applicator  20  and be held between the two crossbars  12 ,  13  of the clip  2 . The supportive rod  19  does in this condition hold the arms  8 - 9  and  10 - 11  in the pairs of the clip  2  apart to create a clip opening  25  configured to receive and close upon tissue, keeping the clip  2  in its first, open state. The protective sheet  21  can be pushed over the clip  2  to make the catheter  18  easier to introduce into the heart  1  and keep the arms  8 - 9  and  10 - 11  in the pairs parallel from the crossbars  12 ,  13  towards the bent portions  16  as shown in  FIG. 3 , the clip  2  still being held substantially in an open state, and more specifically in an intermediate state where the arms are not together as in the second, closed state and are also not at the full distance apart they are in the first, open state depicted in  FIG. 4 . In this way the clip  2  does not get stuck as it is passed into the heart  1 . 
     In  FIG. 4  the protective sheet  21  is drawn back along the applicator  20 , thus uncovering the clip  2  and allowing the clip  2  to take the form of its first, open state. In the first, open state the clip  2  has a clip length  26  and the clip opening  25  has a clip opening width  27 . The clip  2  can then be transformed into its second, closed state by retracting the supportive rod  19  that keeps the crossbars  12 ,  13  of the clip  2  apart. 
     A second alternative embodiment of the catheter  18 ′ is shown in  FIGS. 6 and 7 . The catheter  18 ′ comprises a supportive rod  19 ′ that in the distal end of the catheter can be entered and held between the two crossbars  12 ,  13  of the clip  2  and extend past the connection ends  14 ,  15  of the arms  8 - 9  and  10 - 11  in the pairs. The supportive rod  19 ′ does in this condition hold the arms  8 - 9  and  10 - 11  in the pairs of the clip  2  apart to create a clip opening  25  configured to receive and close upon tissue, thus keeping the clip  2  in its first, open state. 
     In its distal end the supportive rod  19 ′ has a needle  22  that can be used to puncture the interatrial septum. The catheter  18 ′ has an outermost protective sheet  21 ′ that is slidable upon the supportive rod  19 ′. When the catheter  18 ′ is inserted into the heart  1 , the protective sheet  21 ′ covers the clip  2  keeping the arms  8 - 9  and  10 - 11  in the pairs parallel from the crossbars  12 ,  13  towards the bent portions  16  as shown in  FIG. 6  and also covers the needle  22  of the supportive rod  19 ′. However, the clip  2  is still held substantially in an open state with its free ends  16  apart, and more specifically in an intermediate state that is not fully closed or fully open. As the protective sheet  21 ′ is drawn back, it first uncovers the needle  22  allowing it to puncture the interatrial septum and then uncovers the clip  2  allowing it to take the form of its first, open state. In the first, open state the clip  2  has a clip length  26  and the clip opening  25  has a clip opening width  27 . The supportive rod  19 ′ can then be retracted making the clip  2  transform into its second state. 
     The catheter  18 ,  18 ′ could also have an ultrasound probe to provide an easy way for visualizing the device inside the heart  1 . The supportive rod  19 ,  19 ′ could be designed to also provide the ultrasound probe. Ultrasound could also be used in other ways for visualization, e.g. by inserting an ultrasound probe inside the oesophagus. 
     Two alternative methods for inserting the device for treating mitral regurgitation will be described in the following. The insertion is done into a beating heart and can be performed in local anesthesia. 
     Both methods include an introduction of a catheter into the heart. These introductions described below are standard techniques currently used for diagnostic left heart catheterization. 
     The first method uses the catheter  18  shown in  FIGS. 3 and 4 . Referring to  FIG. 5 , the catheter  18  is inserted into the body through the brachial or the femoral artery. The catheter  18  is then passed retrograde along the artery into the left ventricle of the heart  1 . The protective sheet  21  is then retracted as shown in  FIG. 4 , thus uncovering the clip  2 . The clip  2  is now in its first, open state and is used to capture the mitral leaflets  4 ,  5 , preferably in the middle of their free edges. The sharp ends  17  of the bent portions  16  of the arms  8 - 11  give a steady grip on the mitral leaflets  4 ,  5 . The supportive rod  19  is then retracted, thus allowing the clip  2  to transform into its second state. The clip  2  thereby closes and keeps the captured parts of the two mitral leaflets  4 ,  5  together. The clip  2  is now in place to grasp and approximate the free edges of the mitral leaflets  4 ,  5  by the edge-to-edge technique. A double orifice, one on each side of the suture, is thus formed. This double orifice can be closed completely by the mitral valve. Finally, the catheter  18  is retracted from the heart  1 , leaving the clip  2  forming the double orifice. 
     The second method uses the catheter  18 ′ shown in  FIGS. 6 and 7 . The catheter  18 ′ is inserted into the body through the femoral vein. The catheter  18 ′ could be inserted through any other suitable vein, such as the jugular or the subclavian vein. Referring to  FIG. 8 , the catheter  18 ′ is passed along the femoral vein into the vena cava and further into the right atrium. The needle  22  in the distal end of the supportive rod  19 ′ is unsheathed by a retraction of the protective sheet  21 ′ of the catheter  18 ′. The needle  22  is then used to puncture the interatrial septum to give the catheter  18 ′ a passage into the left atrium and then through the mitral valve into the left ventricle. When the catheter has been passed into the left ventricle, the protective sheet  21 ′ is retracted further, whereupon the clip  2  unfolds. The clip  2  is now in its first, open state and the mitral leaflets  4 ,  5  can be captured in the same manner as described for the first method. When the supportive rod  19 ′ is retracted, the clip  2  transforms into its second state, thus closing and keeping the mitral leaflets  4 ,  5  together. The clip  2  is now in place to grasp and approximate the free edges of the mitral leaflets  4 ,  5  by the edge-to-edge technique. As for the first method a double orifice that the mitral valve can close completely is created. Finally the catheter  18 ′ is retracted completely from the body leaving the clip  2  forming the double orifice. 
     When treating tricuspid regurgitation the catheter  18 ′ is used without the needle  22  on the distal end of the supportive rod  19 ′. The catheter  18 ′ is inserted into the body through a vein, such as the femoral, jugular or subclavian veins. The catheter  18 ′ is passed along the vein into the right atrium of the heart  1 . The catheter  18 ′ is then inserted through the tricuspid valve into the right ventricle. Here the protective sheet  21 ′ is retracted to uncover the clip  2  and the capture of the two biggest leaflets of the tricuspid valve could be performed in the same manner as described for the mitral valve described above. Finally, the catheter  18 ′ is retracted leaving the device fixed on two leaflets of the tricuspid valve. 
     Although particular embodiments of the present invention have been described, the application is not limited to these embodiments but includes modifications that are obvious to the skilled man and are comprised in the scope of the invention as defined in the appended claims. For example, it is obvious that different embodiments of clips can be designed. Modifications of the suturing means are possible in numerous ways without extending beyond the spirit of the invention.