Patent Publication Number: US-2023149011-A1

Title: Suturing catheter and relative system for percutaneously reducing mitral insufficiency

Description:
It is the object of the present invention a suturing catheter for reducing mitral insufficiency by applying a suturing point percutaneously, and a relative system for reducing mitral insufficiency by applying suturing points (“edge to edge” technique) percutaneously. 
     Mitral valve insufficiency is a heart disease which affects the mitral valve, one of the four valves located within the heart, whose function is to regulate the passage of blood between the left atrium and the left ventricle. The mitral valve is formed by two flaps, a posterior one (thicker) and an anterior one, attached to a base (mitral ring) and the free edges of the flaps are subtended by the tendon cords attached to the papillary muscles. 
     In physiological conditions, during the diastolic phase of filling the ventricle, the blood flows from the left atrium to the left ventricle by virtue of the opening of the mitral valve. During the systolic phase, when the ventricle contracts and empties, the mitral valve promptly closes, preventing a reflux of blood from the left ventricle to the left atrium. 
     When the mitral valve does not properly close during the phase of emptying the left ventricle, then part of the blood flows back to the left atrium, and this is called mitral valve insufficiency. 
     Moderate-severe mitral insufficiency is traditionally tackled with open heart surgery, since the disease, in addition to being disabling (causing dyspnea due to exertion, palpitation, reduced functional capacity), has a high mortality, equal to 5% per year. 
     Surgical correction of mitral insufficiency may be based on different techniques, including, for example, “edge to edge” technique, developed by Prof. Ottavio Alfieri. This is an operation in which the two mitral flaps are joined in the central portions thereof, with a suturing point (the so-called “Alfieri stitch”) causing the formation of a double exit mitral valve. 
     For some years now, a technique has been developed to repair the mitral valve percutaneously, with an “edge to edge” technique, without the need for a conventional surgery with chest opening, cardiac arrest, extracorporeal circulation. The technique is based on the use of a small metal prosthesis which is positioned in the heart by means of a complex control system, under the guidance of transesophageal angiography, radioscopy and echocardiography. An example of such a prosthesis is shown in US patent document 2012/0041453 A1. 
     The use of such prostheses or clips, however, has some drawbacks: in some cases, it is not possible to position the clip since the flaps are too damaged; usually, it is not possible to place more than one clip, corresponding to a single suturing point; furthermore, in case of incorrect positioning, it is not possible to remove the clip. 
     Suturing catheters are known in the sector for reducing mitral insufficiency by percutaneously applying suturing points, shown, for example, in the documents US 2019/150903 A1 or US 2011/190793 A1. 
     It is the object of the present invention to provide a system for reducing mitral insufficiency which is simple and safe. 
     In particular, it is the object of the present invention to provide a system for reducing mitral insufficiency by percutaneously applying suturing points with an “edge to edge” technique. 
     And again, it is the object of the present invention to provide a system for reducing mitral insufficiency capable of providing at least one suturing point even on very deteriorated mitral flaps, as well as providing more suturing points when required, and also to allow the removal of any suturing points badly positioned, all percutaneously. 
     Such an object is achieved by means of a suturing catheter for reducing mitral insufficiency by applying a suturing point percutaneously, in accordance with claim  1 , and a relative system for reducing mitral insufficiency by applying suturing points (“edge to edge” technique) percutaneously, in accordance with claim  9 . The dependent claims describe preferred embodiments of the invention. 
    
    
     
       The features and advantages of the catheter and of the system for reducing mitral insufficiency according to the present invention will become apparent from the following description, given by way of a non-limiting example, in accordance with the accompanying drawings, in which: 
         FIG.  1 A  shows a sectional view of a heart in which a component of the system for reducing mitral insufficiency according to the present invention is inserted, in particular, a suturing catheter in a positioning step; 
         FIG.  1 B  shows a detail of  FIG.  1 A , in particular, the approaching of the suturing catheter towards a flap of the mitral valve; 
         FIG.  2 A  shows the suturing catheter of  FIG.  1 A  in a step of applying a suturing point on a flap of the mitral valve; 
         FIG.  2 B  shows the suturing catheter of  FIG.  2 A , with a different angle, to better show the application of the suturing point; 
         FIG.  3 A  shows the suturing catheter in accordance with the present invention, in a closed advancement configuration; 
         FIGS.  3 B to  3 D  show in detail the constituent components of the suturing catheter of  FIG.  3 A ; 
         FIG.  4 A  shows the suturing catheter in accordance with the present invention, in a configuration for applying a suturing point; 
         FIGS.  4 B to  4 D  show in detail the constituent components of the suturing catheter of  FIG.  4 A ; 
         FIG.  5 A  shows a further component of the system for reducing mitral insufficiency according to the present invention, in particular, a knotting catheter for knotting suture filaments; 
         FIG.  5 B  shows a detail of the suture filaments of  FIG.  5 A ; 
         FIG.  6    shows a further component of the system for reducing mitral insufficiency according to the present invention, in particular, a cutting catheter for cutting suture filaments. 
     
    
    
       FIG.  1 A  shows a sectioned heart C in which there is a defect of the mitral valve VM whose function is to regulate the passage of blood between the left atrium AS and the left ventricle VS. The mitral valve formed of two flaps, a posterior one, referred to as LP (larger), and an anterior one, referred to as LA. 
     The system for reducing mitral insufficiency according to the present invention comprises at least one suturing catheter  100  as shown in  FIGS.  1 A to  4 D . 
     The suturing catheter  100  comprises a catheter body  101  which extends between a proximal end (not shown) and a distal end  102 . 
     Preferably, the distal end  102  is closed, and possibly rounded and/or tapered to avoid damaging or puncturing the heart tissue during the step of advancing the suturing catheter  100  up to the working position of  FIG.  1 A . 
     The catheter body  101  is provided with at least one internal lumen, defined as a suture lumen  103 , adapted to receive a suture filament  1  that can slide therein, as shown in  FIG.  3 D . 
     In particular, the suture filament  1  is folded into a “U”, with the joining portion (not shown) towards the proximal end of the catheter body  101 , and the two free ends  11  towards the distal end of the catheter body  101 . 
     Therefore, as it may be seen in  FIG.  3 D , the two free ends  11  of the same suture filament  1 , joined together further downstream, slide parallel inside the suture lumen  103 . 
     As shown in  FIG.  3 C , the two free ends  11  of the suture filament  1  are arranged inside the catheter body  101  in a distal position. Each free end  11  of the suture filament  1  is connected to a suture needle  13 . Therefore, the suture filament  1  is connected to a pair of suture needles  13 . 
     Preferably, suture needles  13  are elastic and flexible, made of nitinol and therefore with a shape memory, and have a rectilinear course. 
     The catheter body  101  is also provided with an internal lumen, defined as a catch lumen  104 , adapted to receive a pair of stylets  12  that can slide therein, as shown in  FIG.  3 D . 
     Therefore, as it may be seen in  FIG.  3 D , the two stylets  12  slide parallel inside the catch lumen  104 . 
     As shown in  FIG.  3 C , the distal ends of the stylets  12  are arranged inside the catheter body  101  in the distal position. The distal ends of the stylets are connected to a respective catch needle  15 . Therefore, inside the catheter body  101 , a pair of catch needles  13  is arranged in a distal position. 
     Preferably, the suture lumen  103  has a substantially eight-shaped or slot-shaped section. Such shape allows suture needles  13  to be kept in the correct position, i.e., side by side and facing each other at the respective catch needles  15  (as shown in  FIG.  3 C ), and at the same time allows the sliding of the U-shaped connecting portion of the suture filament  1 . 
     The catch lumen  104  has a substantially eight-shaped, or oval-shaped, section, and simultaneously receives both stylets  12 . 
     In an embodiment variant not shown, the catheter body  101  is provided with a pair of parallel catch lumens  104 , each adapted to receive a respective stylet  12 , sliding therein. 
     It is therefore important that the suture lumen  103  and the catch lumen  104  run parallel inside of the catheter body  101  (as shown in  FIG.  3 D ). In other words, it is important that the plane on which the axes of the two free ends  11  of the suture filament  1  lie is parallel to the plane on which the axes of the stylets  12  lie. 
     As it may be noticed in  FIG.  4 D , the catch needles  15  are provided, at the ends thereof, with a piercing tip  151  adapted to pierce a flap of the mitral valve. 
     Both the catch needles  15  and the suture needles  13  are provided, at the free ends thereof, with a connecting portion adapted to allow a catch needle  15  to mechanically engage with a respective suture needle  13  (as shown in  FIG.  4 D ). 
     The suture needles  13  have a connecting portion  132  preferably in the form of a through hole, or slot, or groove. The catch needles  15  have a connecting portion  152  preferably in the form of a harpoon, or hook. 
     Back to  FIG.  3 A , the suture catheter  100  comprises, at the distal portion, a lever  110  connected to the catheter body  101  by means of a pin  111  which forms the fulcrum of the lever  110 . Therefore, the catheter body  101 , together with the lever  110 , define a staple structure  109  for the suturing catheter  100 . 
     The lever  110  comprises a stapling arm  112  which, together with the catheter body  101 , defines a catch zone  113  of a flap of the mitral valve. 
     Preferably, the suture lumen  103  at least partially extends also inside the stapling arm  112 . Therefore, the suture lumen  103  has an initial rectilinear course inside the catheter body  101 , a curvilinear course in the passage zone towards the lever  110 , and a final, again rectilinear, course inside the stapling arm  112 . It should be noted that the suture needles  13  are arranged inside the stapling arm  112  and at least partially at the curve of the suture lumen  103  ( FIG.  3 C ). 
     The stapling arm  112  is provided with an engagement opening  119 , in the form of a through hole, preferably in the form of a slot. At the engagement opening  119 , the connecting portions of the catch needles  15  and of the suture needles  13  meet, engaging with each other (as shown in  FIG.  4 D ). 
     The suture lumen  103  ends in a distal outlet  107 , obtained in the stapling arm  112 , at the engagement opening  119 . The catch lumen  104  ends in a distal outlet  108  obtained in the catheter body  101 , which faces the engagement opening  119 . 
     The suturing catheter  100  therefore comprises two suture needles  13  (parallel) and two catch needles  15  (parallel) contained inside a respective channel (suture lumen  103  and catch lumen  104 ) which is open towards the engagement opening  119 . 
     The lever  110  further comprises an opposite operating arm  114  which, together with the catheter body  101 , defines an operating zone  115  of the staple  109 . 
     Preferably, the catch zone  113  is arranged in a position close to the fulcrum  111  and/or to the operating zone  115 . 
     The catheter body  101  is also provided with an internal lumen, defined as a control lumen  105 , adapted to receive a control mandrel  16  that can slide therein, as shown in  FIG.  3 D . 
     Preferably, the control lumen  105  has a substantially circular section. 
     As shown in  FIG.  3 C , the distal end of the control mandrel  16  is arranged inside the catheter body  101  in the distal position. Such distal end of the control mandrel  16  is connected, by means of a joining means  161 , to the operating arm  114  of the lever  110 . By retracting the control mandrel  16 , the operating arm  114  is dragged into the closing position of the staple  109 . By advancing the control mandrel  16 , the operating arm  114  is pushed by the joining means  161  into the opening position of the staple  109 . 
     Preferably, the joining means  161  is a relatively rigid loop engaged with the operating arm  114 . Such solution is preferable, since the traction forces on the operating arm  114  are better distributed. 
     In an alternative example, the joining means is a traction wire engaged with the operating arm  114 . 
     The operating arm  114 , and consequently the staple structure  109  of the suturing catheter  100 , may be operated by means of the control mandrel  16  between a closing position (as in  FIG.  3 A ) and an opening position (as in  FIG.  4 A ). 
     In use, the suturing catheter  100  is advanced with staple  109  in the closing position ( FIG.  1 B ). Once the zone to be treated is reached, the control mandrel  16  is advanced so as to push the operating arm  114  of the lever  110  towards the opening configuration of the staple  109  ( FIG.  4 A ). It should be noted that the operating arm  114  of the lever  110  is pushed towards the opening configuration of the staple  109  also by the blood flow and by the elastic force of the suture needles  13  which, when resting, have a rectilinear configuration, and are now forced inside of the curvilinear portion of the suture lumen  103 . 
     The suturing catheter  100 , with the staple  109  open, is retracted until it catches a flap LP of the mitral valve inside the catch zone  113 . By retracting the control mandrel  16 , the operating arm  114  of the lever  110  is dragged towards the closing configuration of the staple  109  so as to pinch and firmly hold the flap LP of the mitral valve inside the catch zone  113 . 
     At this point, the distal outlet  107  of the suture lumen  103  is aligned with the distal outlet  108  of the catch lumen  104 . The catch needles  15  are advanced, pushing the respective stylets  12 , so as to pierce, from side to side, the flap LP of the mitral valve. The catch needles  15  are advanced up to the inside of the engagement opening  119 , in which they mechanically engage (by virtue of the harpoon shape thereof) with the respective suture needles  13  ( FIG.  4 A ). 
     By retracting the stylets  12 , and the catch needles  15  therewith, it is possible to drag the suture needles  13  inside the catch lumen  104 , and also the suture filament  1  therewith, until the U-shaped joining portion of the filament itself is positioned on the mitral flap LP. A suturing point was thus obtained. 
     By virtue of the presence of the suture needles  13 , the two free ends  11  of the suture filament  1  are inserted inside a microcatheter  20  (preferably a monorail one) which allows to remove the suturing catheter  100  without friction on the ends of the of suture filament  1 . 
     The above operation is repeated so as to position a second suturing point on the opposite mitral flap LA, and possibly also a third or fourth suturing point, if required. 
     Preferably, the system for reducing mitral insufficiency according to the present invention further comprises at least one knotting catheter  200  for knotting the suture filaments  1 , shown in  FIGS.  5 A and  5 B . 
     The knotting catheter  200  comprises a catheter body  201  which extends between a proximal end (not shown) and a distal end  202  which ends in a distal opening  203 . 
     The catheter body  201  is provided with at least one internal lumen, defined as a containment lumen  204 , adapted to receive, sliding therein, at least one microcatheter  20  in which the suture filament  1  forming the suturing point on the mitral flap LP, previously positioned with the suturing catheter  100 , is accommodated. 
     At the distal end  202 , preferably along the edge of the catheter body  201  defining the distal opening  203 , a tightening filament  210  is accommodated, adapted to knot together the two free ends  11  of the suture filaments  1 . 
     The tightening filament  210  comprises a loop (not shown, since it is accommodated inside a special seat  214 ), a slip knot  211 , a constricting flap  212  that can reduce the diameter of the loop, and a fixing flap  213  that can tighten the slip knot  211 . Preferably, the constricting flap  212  and the fixing flap  213  are different in terms of geometry, or surface, or color, so that they may be easily distinguished from each other. 
     The loop is accommodated in a seat  214 , for example a ring-shaped seat, obtained on the edge of the catheter body  201  defining the distal opening  203 . 
     The seat  214  is provided with an opening portion  215 , also ring-shaped, obtained by pre-incision, or pre-cut, or weakening. 
     Preferably, the opening portion  215  faces towards the inside of the containment lumen  204 . 
     During use, the microcatheters  20  containing the suture filaments  1  are inserted inside the knotting catheter  200 . The distal end  202  of the knotting catheter  200  is approached to the valve flaps LP, LA on each of which at least one suturing point has been placed. By approaching the knotting catheter  200 , and keeping the ends of the suture filaments  1  under tension, the mitral flaps are brought closer by reducing the section of the mitral valve and thus obtaining the desired effect of the Alfieri operation. During this step it is possible to evaluate the effectiveness of the section reduction, and possibly to modify it on the basis of the degree of residual insufficiency (by positioning the knotting catheter  200  more or less forward). Once the optimal residual section has been defined, the suture filaments are knotted together. In particular, by pulling the constricting flap  212  of the tightening filament  210 , the diameter of the loop is reduced and comes out of the seat  214  through the opening portion  215 . The diameter of the loop is reduced until all the suture filaments  1  are enclosed in a single bundle. At this point, by pulling the fixing flap  213  of the tightening filament  210 , the slip knot  211  tightens to lock the loop in the position for tightening the suture filaments  1 . Once the suture filaments  1  have been knotted, it is possible to remove the knotting catheter  200 . 
     Preferably, the system for reducing mitral insufficiency according to the present invention further comprises at least one cutting catheter  300  for cutting the ends of the suture filaments  1  and of the tightening filament  210 , shown in  FIG.  6   . 
     The cutting catheter  300  comprises a catheter body  301  which extends between a proximal end (not shown) and a distal end  302  which ends in a distal opening  303 . 
     The catheter body  301  is provided with at least one internal lumen, defined as a main lumen  304 , adapted to receive, sliding therein, the ends of the suture filaments  1  forming the suturing points on the mitral flap LP previously positioned with the suturing catheter  100 , and the ends of the tightening filament  210 . 
     Inside the main lumen  304 , an abutment element  305  is accommodated, against which a blade  306  acts. 
     The catheter body  301  is provided with a further internal lumen, defined as a secondary lumen  308 , adapted to receive a blade  306  and a relative operating mandrel  307 . 
     In the resting configuration, the blade  306  is received inside the secondary lumen  308  so as not to interfere with the filaments sliding inside the main lumen  301 . By retracting the operating mandrel  307 , the blade  306  comes out of the secondary lumen  308  towards and inside the main lumen  304 . The blade intercepts the filaments until pushing them in abutment against the abutment element  305  and therefore cuts the aforesaid filaments. 
     During use, the suture filaments  1  and/or the tightening filament  210  are inserted inside the cutting catheter  300 . The distal end  302  of the cutting catheter  300  is approached to the valve flaps LP, LA until the desired position is reached. At this point, the blade  306  is operated to cut the aforesaid filaments. 
     Innovatively, a catheter and a system for reducing mitral insufficiency in accordance with the present invention is easy to use, safe and particularly effective. 
     Advantageously, a system for reducing mitral insufficiency in accordance with the present invention allows the treatment of mitral insufficiency by percutaneously applying suturing points with an “edge to edge” technique. 
     Advantageously, a catheter and a system for reducing mitral insufficiency in accordance with the present invention is capable of performing at least one suturing point even on very deteriorated mitral flaps. 
     Advantageously, a system for reducing mitral insufficiency in accordance with the present invention allows to position more suturing points on the same mitral flap when required. 
     Advantageously, a system for reducing mitral insufficiency in accordance with the present invention allows the removal of any badly positioned suturing points. 
     It is apparent that those skilled in the art may modify the object described above, without departing from the scope of protection as defined by the following claims.