(19)
(11)EP 2 693 985 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.07.2020 Bulletin 2020/31

(21)Application number: 12722904.5

(22)Date of filing:  04.04.2012
(51)International Patent Classification (IPC): 
A61F 2/24(2006.01)
A61B 17/04(2006.01)
(86)International application number:
PCT/IL2012/050126
(87)International publication number:
WO 2012/137208 (11.10.2012 Gazette  2012/41)

(54)

Device for heart valve repair

Vorrichtung zur Reparatur einer Herzklappe

Dispositif pour la réparation de valvule cardiaque


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 04.04.2011 US 201161471497 P
11.04.2011 US 201161473873 P

(43)Date of publication of application:
12.02.2014 Bulletin 2014/07

(73)Proprietor: The Medical Research, Infrastructure, And Health Services Fund Of The Tel Aviv Medical Center
64239 Tel-aviv (IL)

(72)Inventors:
  • KUDLIK, Nachman
    69185 Tel Aviv (IL)
  • PEVNAY, Demitry
    71700 Modi'n (IL)

(74)Representative: Grünecker Patent- und Rechtsanwälte PartG mbB 
Leopoldstraße 4
80802 München
80802 München (DE)


(56)References cited: : 
US-A1- 2005 075 654
US-A1- 2007 118 151
US-A1- 2009 276 038
US-A1- 2005 119 735
US-A1- 2008 009 888
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    FIELD OF THE INVENTION



    [0001] This invention relates to medical devices, and more specifically to such devices for treating a heart valves.

    BACKGROUND OF THE INVENTION



    [0002] In the heart, the mitral valve is located between the left atrium and the left ventricle, while the tricuspid valve is located between the right atrium and the right ventricle. Each valve consists of thin leaflets, located between the atrium and the ventricle. The valve leaflets are attached to the inner wall of the ventricle by a series of fibers called chordae. In a healthy heart, when the ventricles contract during systole, the valve leaflets are apposed and thus prevent backflow of blood from the ventricle into the atrium. When the ventricles relax during diastole, the valve opens to allow blood to flow from the atrium into the ventricle.

    [0003] In mitral valve prolapse, the chordaes have become elongated due to myxomatous degeneration in which collagen in the heart structures forms abnormally and causes thickening, enlargement, and redundancy of the leaflets and chordae. In addition this process may causes rupture of chordae. Under these conditions, the leaflets prolapse (flap backwards into the left atrium) during systole when the ventricles contract, allowing regurgitation of blood through the valve from the ventricle into the atrium. When severe, mitral regurgitation leads to heart failure and abnormal heart rhythms.

    [0004] Mitral valve prolapse is the most common heart valve abnormality, affecting five to ten percent of the world population. Significant (moderate to severe) mitral regurgitation is much less common. For example, in one study of two million untreated people in the U.S, moderate or severe mitral regurgitation was found to occur in about 2-3 percent of people

    [0005] Surgery is required for people with severe mitral regurgitation. Guidelines from the American Heart Association and European Society of Cardiology define a person as having severe chronic mitral regurgitation based upon echocardiogram measurements of the heart, heart valves, and blood flow. Mitral valve surgery is a major, open-heart, surgical procedure. The heart is arrested during critical parts of the operation, while oxygenated blood is pumped throughout the body with a heart-lung machine. A small part of the heart is then opened to expose the mitral valve.

    [0006] Methods for non-invasive or minimally invasive mitral valve prolapse repair have been developed.

    [0007] One method for treating heart valve prolapse involves binding together the two leaflets along the free edges of the leaflets using a clip. A method and system for suturing valve leaflets is disclosed, for example, in US Patent 8,062,313 to Kimblad. A clip for holding together valve leaflets is disclosed, for example, in US Patent 8,029,518 to Goldfarb et al.

    [0008] Another method of valve repair involves introducing one or more artificial filaments to replace torn chordate. The filaments, sometimes referred to as "neochordae", are attached at one end to a valve leaflet and at another end to cardiac tissue. A system of this type is disclosed, for example, in US Patent 8,043,368 to Crabtree. These methods require reliable determination of the required length of the neochordae to be introduced, which can be difficult to obtain in a beating heart. In most systems of this type it is difficult to adjust the lengths of the neochordae after deployment.

    [0009] US 2007/0118151 relates to a method and system to achieve leaflet coaptation in a cardiac valve percutaneously by creation of neochordae to prolapsing valve segments. This technique is disclosed as being especially useful in cases of ruptured chordae, but may be utilized in any segment of prolapsing leaflet.

    [0010] US 2009/0276038 relates to a tissue connecting device. Disclosed is a valve support structure which includes a central body, a first leaflet clamp defining an upper compressive portion, and a second leaflet clamp defining a lower compressive portion. The two clamps may be positioned to engage the valve leaflets therebetween.

    [0011] US 20050119735 relates to catheter based systems and methods for securing tissue including the annulus of a mitral valve. The systems and methods employ catheter based techniques and devices to plicate tissue and perform an annuloplasty.

    [0012] US 2005/075654 relates to devices and methods for improved soft tissue securement, and to tissue anchoring elements and deployment thereof. Such tissue anchoring elements may comprise a linkage element and an array of spreading elements.

    [0013] US 2008/009888 relates to tissue anchors, which include a flat, broad, and large contact surface for engagement with a portion of tissue. Several embodiments of composite tissue anchors include a support element and an overlay element. Tissue anchor assemblies include two or more tissue anchors, a connector, and a cinching mechanism. In some embodiments, the tissue anchors included in the tissue anchor assemblies are of different types, sizes, and/or shapes.

    SUMMARY OF THE INVENTION



    [0014] The invention provides a device for treating a heart valve according to claim 1 and a system for treating a heart valve according to claim 4. Preferred embodiments are listed in the dependent claims.

    [0015] In one of its aspects, the present invention provides a device for treating a mitral or tricuspid valve. The device of the invention comprises an anchor having an expanded configuration in which the anchor is deployed on both sides of the prolapsed area of a valve leaflet to be treated, and a low caliber configuration in which the anchor is delivered to the site of its deployment. One or more sutures are attached to the anchor. After deployment of the anchor on the valve leaflet being treated, the sutures pass ventricle wall and are then sewn outside the ventricle wall to function as prosthetic
    chordae, as explained below. The proper length of the artificial chordae can be obtained under echocardiography.

    [0016] The anchor may have any form that allows the anchor to be applied to both of the leaflet surfaces.

    [0017] In its second aspect, the present invention provides a delivery system for delivering the device of the invention to the site of its deployment in the body. The delivery system comprises a needle into which the device of the invention can be inserted with the anchor in its undeployed configuration. The delivery system further comprises a catheter dimensioned to receive the needle, and a pusher that is used to push the device through the needle, as explained below.

    [0018] In use, device of the invention in its undeployed configuration is inserted into the needle and the needle is inserted into the catheter or thess. The tube is inserted through a chest incision, and into the ventricle via apex until the echo guided tip of the tube is just below the prolapsed area of the leaflet to be treated. The device is then pushed in the needle until the tip of the needle pierces the valve leaflet being treated. The anchor is then released from the needle and allowed to attain its deployed configuration on both sides of the leaflet being treated. Attainment of the deployed configuration may occur spontaneously upon release of the anchor from the tube (for example, if the anchor is made from a resiliently flexible material), or upon a temperature transition, in the case of a anchor formed from a shape memory alloy such as Nitinol. The anchor may be coated, for example, with pericardium or various drugs such as antibiotics.

    [0019] After deployment of the anchor, the sutures are tied outside the left ventricle wall so as to allow the sutures to function as prosthetic chordate.

    [0020] The disclosure also provides a method for treating a heart valve comprising:
    1. (a) providing a system for treating a heart valve comprising:
      1. i) A device for treating a heart valve comprising:

        an anchor having an expanded deployed configuration and a low caliber undeployed configuration; and

        one or more sutures attached to the anchor;

      2. ii) a delivery catheter having a catheter lumen having proximal end and a distal end;
      3. iii) a needle slidable in the catheter lumen, the needle having a needle lumen dimensioned to receive the device in the low caliber configuration of the device, the needle further having a sharp tip; and
      4. iv) a rod configured to push the device in the needle lumen towards the distal end of the catheter.
    2. (b) inserting the device into the delivery system;
    3. (c) inserting the distal end of the catheter through myocardium of the heart, until the catheter tip is juxtaposed to the underside of the leaflet;
    4. (d) piercing the leaflet with the sharp tip of the needle;
    5. (e) pushing the rod towards the tip of the needle until the anchor in its undeployed configuration passes through the needle tip and is released from the catheter;
    6. (f) bringing the anchor to it deployed configuration on one or both surfaces of the valve leaflet.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0021] In order to understand the disclosure and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

    Fig. 1 shows a device for treating a heart valve leaflet from a first perspective in accordance with one embodiment of the invention;

    Fig. 2 shows the device of Fig. 1 from a second perspective;

    Fig. 3 shows the device of Fig. 1 in an undeployed configuration;

    Fig. 4 shows a device having a wire loop for treating a heart valve leaflet in accordance with an embodiment not falling under the invention;

    Fig. 5 shows the device of Fig. 4 in an undeployed configuration;

    Fig. 6 shows a rod device for treating a heart valve leaflet in accordance with an embodiment not falling under the invention;

    Fig. 7 shows the device of Fig. 6 in an undeployed configuration;

    Fig. 8 shows a delivery system for delivering and deploying a device of the invention;

    Fig. 9a shows delivery of a device of the invention to a heart valve leaflet;

    Fig. 9b shows piercing a heart valve leaflet with a needle;

    Fig. 9c shows a first stage in the deployment of a device of the invention at a heart valve;

    Fig. 9d shows a second stage in the deployment of a device of the invention at a heart valve; and

    Fig. 9e shows a device of the invention after deployment in a heart valve and removal of the delivery device.


    DETAILED DESCRIPTION OF EMBODIMENTS



    [0022] Figs. 1 to 3 show a device 50 for treating a heart valve in accordance with one embodiment of the invention. The device 50 has an expanded configuration shown from different perspectives in Figs. 1 and 2 in which the device 50 is deployed in a heart chamber, as explained below. The device 50 also has a low caliber undeployed configuration, shown in Fig. 3, which is used during delivery of the device 2 to a heart valve.

    [0023] The device 50 has an anchor portion 51 comprising a central hub 52 from which extend a plurality of loops 54 and 56. The hub 52 is a tube that is completely closed at the distal end of the tube, for example, by plugging the distal end of the tube with an adhesive 53. In the embodiment of Figs. 1 to 3, there are 12 loops. This is by way of example only, and the device 50 may have any number of loops are required in any application. The device 50 includes six coplanar loops 54 and another six loops 56 located below the plane of the loops 54 and which curve upwards towards the plane of the loops 54. The loops 54 and 56 are made from a single piece of wire that may be for example, a Nitinol™ wire having a diameter of about 0.2 mm. The anchor may be coated with bovine pericardium in order to enhance integration of the anchor in the leaflet.

    [0024] Two sutures 58 and 60 are attached at one end to the hub 52 and extend away from the anchor portion. The sutures 58 and 60 may be, for example, GoreTex ePTFE fibers.

    [0025] In the compressed configuration shown in Fig. 3, the flat loops 54 and 56 are collapsed upwards away from the hub 52 and filaments 58 and 60, while the curved loops 56 are folded downwards towards the hub and filaments 58 and 60, so that the device 50 attains a low caliber suitable for delivery to the site of its deployment in a heart chamber.

    [0026] Figs. 4 and 5 show a device 2 for treating a heart valve in accordance with an embodiment not falling under the invention. The device 2 has an anchor portion 4 comprising an elliptical wire ring, with one or more cross elements. Two cross elements 6 and 8 are shown in Figs. 4 and 5. This is by way of example only, and the anchor 4 may any number of cross elements. The device 2 has an expanded configuration shown in Fig. 4 in which the device 2 is deployed in a heart chamber and a low caliber undeployed configuration, shown in Fig. 5, which is used during delivery of the device 2 to a heart valve. A pair of sutures 12 and 14 are tied at one end to the cross elements 6 and 8. The other ends of the sutures 12 and 14 are free prior to deployment of the device 2 in a heart valve, as explained below. The sutures may be, for example, Gortex sutures.

    [0027] The anchor 4 is formed from a deformable material that allows the anchor 4 in the deployed configuration (Fig.4) to be collapsed into the undeployed configuration (Fig. 5) prior to delivery of the device, and then to regain the deployed configuration after proper positioning in the heart. The wires of the anchor 4 may be made, for example, from a biocompatible elastic or spring-like material, such as silicone rubber, stainless steel or Nitinol. Alternatively, the wires of the anchor 4 may be made from a shape memory alloy (one-way or two-way), in which case the anchor 4 can alternate between the deployed configuration and the undeployed configuration by an appropriate transition of temperature, as is known in the art of shape memory alloys. The anchor may be coated with bovine pericardium in order to enhance integration of the anchor in the leaflet.

    [0028] Figs. 6 and 7 show a device 60 for treating a heart valve in accordance with another embodiment not falling under the invention. The device 60 has an anchor portion 62 comprising wire rod 64. The rod 64 may be made, for example, from a biocompatible elastic or spring-like material, such as silicone rubber, stainless steel or Nitinol. The device 60 has an expanded configuration shown in Fig. 6 in which the device 60 is deployed in a heart chamber and a low caliber undeployed configuration, shown in Fig. 7, which is used during delivery of the device 60 to a heart valve. A pair of sutures 64 and 66 are tied to the rod 64 at the center of the rod 64. The other ends of the sutures 64 and 66 are free prior to deployment of the device 60 in a heart valve, as explained below. The sutures may be, for example, Gortex sutures. The rod 64 may be coated with bovine pericardium in order to enhance integration of the anchor in the leaflet.

    [0029] Fig. 8 shows the device 50 of Figs 1 and 2 in its undeployed configuration inserted into a delivery system 20. The delivery system 20 comprises a delivery catheter 23 having a proximal end 21 and a distal end 29, that is visible under echocardiography. The delivery system 20 also comprises a needle 22 into which the device 50 is inserted in its undeployed configuration. The needle 22 terminates at its distal end in a sharp tip 24 that is used to pierce the valve leaflet being treated during deployment of the device 2. The delivery system 20 further comprises a pushing rod 26 dimensioned to be slidable within the needle 22. The rod 26 is longer than the needle 22 so as to be accessible at the proximal end of the delivery system 20 during delivery of the device 50. The rod 26 is used to push the device 50 through the tip 24 of the needle 22 during deployment of the device 50. The catheter 23 terminates in a blunt tip 25 at its distal end. Attached to the blunt tip 25 is a spiral wire 27 configured to screw into the underside of the valve leaflet being treated, as explained below.

    [0030] Also at the distal end of the catheter 23 is a toroidal shaped balloon 28 that is visible in echocardiography.. A delivery tube is provided with a Luer fitting for attachment of a syringe containing a liquid such as sterilized water or saline. The liquid is delivered to the balloon 28 via the delivery tube 100 and enters the balloon 28 through one or more apertures 102. As the balloon 28 is filled with the liquid, and residual air in the balloon or excess liquid is forced out of the balloon 28 through a second set of one or more apertures 104 into a return tube 106 to the proximal end of the catheter 23. The delivery tube 100 and the return tube 106 may be continuous with each other. This allows complete removal of any air in the balloon 28.

    [0031] Deployment of the device of the invention for the treatment of a prolapsed mitral valve will now be described with reference to the device 50 shown in Figs. 1 and 2, it being self-evident that other embodiments of the device of the invention may be deployed in a similar fashion.

    [0032] Fig. 9 shows a method for deploying the device 50 for treatment of a prolapsed mitral valve. Fig. 9a shows a cut away view of a left ventricle 30 including a posterior mitral valve leaflet 32 and an anterior mitral valve leaflet 34. Malocclusion of the leaflets 32 and 34 is evident by a space 36 between the leaflets due to elongation of the chordae 35. For deployment of a device 50, the device 50 is inserted into the delivery system 20, as shown in Fig. 8. The tip 25 of the catheter 23 is inserted through the myocardium 38, until the catheter tip 25 is juxtaposed to the underside of the leaflet 32. Movement of the delivery system in the left ventricle, and deployment of the device may be monitored by echocardiography of the balloon 23. Bleeding can be controlled by a purse string suture. With the heart still beating or while using frequent heart pacing, the catheter 23 is rotated so as to screw the spiral wire 27 into the underside of the valve leaflet 32. Then as shown in Fig. 9b, the sharp tip 24 of the needle 22 is made to pierce through the leaflet 32.

    [0033] Now, as shown in Fig. 9c, the rod 26 is pushed towards the tip 24 of the needle causing the anchor region 51 in its undeployed configuration to pass through the needle tip 24 and to be released from the catheter 23 with the upper loops 54 positioned in the left atrium above the leaflet 32 and the curved loops 56 positioned in the ventricle below the leaflet 32. At this point the anchor 51 is allowed to attain its deployed configuration (Fig. 9d). This may occur spontaneously upon release of the anchor from the tube 22 (for example, if the anchor is made from a resiliently flexible material), or upon a temperature transition, in the case of a anchor formed from a shape memory alloy such as Nitinol. As the delivery system 20 is removed from the left ventricle, the sutures 12 and 14 are pulled downwards the proper length of neochordaes may be monitored by echocardiography. The sutures continue to be pulled until the leaflets are apposed, and the space 36 is eliminated (Fig. 9e), so that the mitral regurgitation has been corrected. When the correct length of the sutures has been determined, the sutures are fixed to the myocardium 38 so that the sutures can function as prosthetic chordaes.


    Claims

    1. A device (50) for treating a heart valve comprising:

    (a) an anchor (51) applicable to both surfaces of a valve leaflet and having an expanded deployed configuration and a low caliber undeployed configuration; and

    (b) one or more sutures (58, 60) attached to the anchor (51), wherein the anchor (51) in the deployed configuration comprises a first set of one or more wire loops (54) lying in a first plane and a second set of one or more wire loops (56) not lying in the first plane,
    wherein the anchor portion (51) comprises a central hub (52) from which the two sets of one or more wire loops (54, 56) extend;
    characterized in that
    the second set of wire loops (56) are curved towards the first plane.


     
    2. The device according to claim 1, wherein, in the low caliber undeployed configuration, the first set of loops are collapsed away from the central hub and the sutures and the second set of loops are collapsed towards the central hub and the sutures.
     
    3. The device according to any one of claims 1 or 2, wherein the central hub is a tube that is completely closed at the distal end of the tube.
     
    4. A system for treating a heart valve comprising:

    (a) a device for treating a heart valve according to any one of the previous claims;

    (b) a delivery catheter having a catheter lumen having proximal end and a distal end; and

    (c) a needle slidable in the catheter lumen, the needle having a needle lumen dimensioned to receive the device in the low caliber configuration of the device, the needle further having a sharp tip.


     
    5. The system according to claim 4, further comprising a rod configured to push the device in the needle lumen towards the distal end of the catheter.
     
    6. The system according to claim 4 or 5, wherein the distal end of the catheter is provided with a spiral wire.
     
    7. The system according to Claim 4 or 5, wherein the distal end of the catheter is provided with an inflatable balloon that is visible in echocardiography.
     


    Ansprüche

    1. Vorrichtung (50) zur Behandlung einer Herzklappe, die umfasst:

    (a) einen Anker (51), der auf beide Oberflächen eines Klappensegels anwendbar ist und eine erweiterte entfaltete Konfiguration und eine niedrigkalibrige nicht entfaltete Konfiguration hat; und

    (b) ein oder mehrere Nahtfäden (58, 60), die am Anker (51) befestigt sind,

    wobei der Anker (51) in der entfalteten Konfiguration einen ersten Satz von einer oder mehreren Drahtschlaufen (54), die in einer ersten Ebene liegen, und einen zweiten Satz von einer oder mehreren Drahtschlaufen (56) umfasst, die nicht in der ersten Ebene liegen,
    wobei der Ankerteil (51) eine zentrale Nabe (52) umfasst, von der sich die beiden Sätze von einer oder mehreren Drahtschlaufen (54, 56) erstrecken;
    dadurch gekennzeichnet, dass
    der zweite Satz von Drahtschlaufen (56) zur ersten Ebene hin gekrümmt ist.
     
    2. Vorrichtung nach Anspruch 1, wobei in der niedrigkalibrigen, nicht entfalteten Konfiguration der erste Satz von Schlaufen von der zentralen Nabe und den Nähten weg zusammenfällt und der zweite Satz von Schlaufen zur zentralen Nabe und den Nähten hin zusammenfällt.
     
    3. Vorrichtung nach einem der Ansprüche 1 oder 2, wobei die zentrale Nabe ein Rohr ist, das am distalen Ende des Rohres vollständig geschlossen ist.
     
    4. System zur Behandlung einer Herzklappe, das umfasst:

    (a) eine Vorrichtung zur Behandlung einer Herzklappe nach einem der vorhergehenden Ansprüche;

    (b) einen Zuführungskatheter mit einem Katheterlumen mit einem proximalen Ende und einem distalen Ende und

    (c) eine im Katheterlumen verschiebbare Nadel, wobei die Nadel ein Nadellumen hat, das so dimensioniert ist, dass es die Vorrichtung in der niedrigkalibrigen Konfiguration der Vorrichtung aufnimmt, wobei die Nadel des Weiteren eine scharfe Spitze hat.


     
    5. System nach Anspruch 4, das des Weiteren einen Stab umfasst, der konfiguriert ist, um die Vorrichtung im Nadellumen zum distalen Ende des Katheters zu schieben.
     
    6. System nach Anspruch 4 oder 5, wobei das distale Ende des Katheters mit einem Spiraldraht bereitgestellt wird.
     
    7. System nach Anspruch 4 oder 5, wobei das distale Ende des Katheters mit einem aufblasbaren Ballon bereitgestellt wird, der in der Echokardiographie sichtbar ist.
     


    Revendications

    1. Dispositif (50) de traitement d'une valve cardiaque comprenant :

    (a) une ancre (51) applicable aux deux surfaces d'un feuillet de valve et présentant une configuration déployée expansée et une configuration non déployée de faible calibre ; et

    (b) une ou plusieurs sutures (58, 60) fixées à l'ancre (51),

    l'ancre (51) dans la configuration déployée comprenant un premier ensemble d'une ou plusieurs boucles de fil (54) reposant dans un premier plan et un second ensemble d'une ou plusieurs boucles de fil (56) ne reposant pas dans le premier plan,
    la portion d'ancrage (51) comprenant un moyeu central (52) depuis lequel les deux ensembles de l'une ou plusieurs boucles de fil (54, 56) s'étendent ;
    caractérisé en ce que
    le second ensemble de boucles de fil (56) est incurvé vers le premier plan.
     
    2. Dispositif selon la revendication 1, dans la configuration non déployée de faible calibre, le premier ensemble de boucles est replié loin du moyeu central et les sutures et le second ensemble de boucles sont repliés vers le moyeu central et les sutures.
     
    3. Dispositif selon l'une quelconque des revendications 1 ou 2, le moyeu central est un tube qui est entièrement fermé à l'extrémité distale du tube.
     
    4. Système de traitement d'une valve cardiaque comprenant :

    (a) un dispositif de traitement d'une valve cardiaque selon l'une quelconque des revendications précédentes ;

    (b) un cathéter de pose ayant une lumière de cathéter ayant une extrémité proximale et une extrémité distale ; et

    (c) une aiguille pouvant coulisser dans la lumière de cathéter, l'aiguille ayant une lumière d'aiguille dimensionnée pour recevoir le dispositif dans la configuration de faible calibre du dispositif, l'aiguille ayant en outre une pointe aiguë.


     
    5. Système selon la revendication 4, comprenant en outre une tige configurée pour pousser le dispositif dans la lumière d'aiguille vers l'extrémité distale du cathéter.
     
    6. Système selon la revendication 4 ou 5, l'extrémité distale du cathéter étant pourvue d'un fil en spirale.
     
    7. Système selon la revendication 4 ou 5, l'extrémité distale du cathéter étant pourvue d'un ballonnet gonflable qui est visible en échocardiographie.
     




    Drawing
































    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description