Patent Application
20240023951
The present invention relates to a catheter device for repair of the heart by implanting an artificial chordae line, a method of use of a catheter device for repair of the heart by implanting an artificial chordae line, and a method of manufacture of a catheter device for repair of the heart by implanting an artificial chordae line.
The chordae tendineae are cord-like tendons that connect the papillary muscles to the tricuspid valve and the mitral valve in the heart. The valves consist of leaflets that open and close with the beating of the heart in order to control blood flow and blood pressure within the heart.
Mitral valve disease presents an important challenge to cardiac surgeons and cardiologists. Mitral regurgitation has become the leading pathophysiological condition of the mitral valve in the developed world. One of the most important causes of regurgitation is prolapse of one of the mitral leaflets. The pathological abnormality that requires repair is rupture or other degenerative changes of the chords, leaflet or other related structures. When the chord(s) remain intact, the mitral leaflets open and close synchronously and in a fashion that prevents leakage of the valve. The normal chords can rupture acutely causing acute decompensation, in the form of, heart failure. This usually results in an emergency condition requiring rapid intervention. Damage to the chord(s) can also occur more slowly including rupturing or elongation due to degenerative processes, causing the mitral valve to develop leaks or regurgitation.
Surgical repair of the mitral valve has become relatively standardized, using resection of the prolapsed leaflet and/or implantation of new, artificial chordae lines to control leaflet motion. In addition a mitral ring is frequently placed to shrink the size of the mitral valve annulus. Surgical replacement of ruptured or elongated chords is highly effective in eliminating or minimizing mitral valve regurgitation. The procedure is presently performed with open heart surgery techniques. This requires use of cardiopulmonary bypass and arresting of the heart. This surgical approach, although working well, is a highly invasive procedure which can cause serious complications, long hospital stays and substantial expense. Consequently a less invasive approach would be preferable.
Insertion of mitral leaflet chords has been done using a minimally invasive surgical approach entering the heart through its apex. The technique, was developed by the company Neochord Inc. and is described, for example, in WO 2012/167120, but still requires a surgical incision and the chords do not get inserted in the papillary muscles where they normally should be fixed.
WO 2008/101113 describes another example of a system for repair of the heart, including implantation of artificial chordae lines. In the described method an anchor can be attached to the papillary muscle and is coupled to the leaflet of the mitral valve by an artificial chordae line, a suture and a clip. The clip allows for adjustment of the length of the artificial chordae line. A complex multi-stage process is required to implant the papillary anchor and the suture and join them together. The papillary anchor is formed of a memory metal such as nitinol and has a ‘flowered’ shape with sharp ‘petals’ for hooking the anchor to body tissue. The flowered shape is flattened into a tube shape and held in a tube that is passed into the heart. The tube and anchor are then pressed against the papillary muscle and the anchor is pushed out of the tube so that the petals pierce the muscle and fold outward through the muscle to provide a secure coupling of the anchor to the muscle tissue. In a subsequent surgical procedure, an artificial chordae line may be attached to the anchor. Then in a further step, the suture is attached to the leaflet and this suture is joined to the chord by the clip. The suture is attached to the leaflet by locating a vacuum port near to the leaflet and pulling it into the vacuum port where it can be pierced.
It will be appreciated that this technique, whilst avoiding open heart surgery, still requires a sequence of relatively complex steps. The number of steps required increases the risk. Furthermore, the complexity of the device means that parts implanted within the body are at risk of coming loose and injuring the patient by embolization. In particular, the clip could come loose from the anchors. It is also thought that the use of a suture with an additional clip, as proposed, may not effectively repair the heart valve since it will not closely simulate a natural chord.
In earlier patent applications, WO2016/042022 and WO2020/109596, the present applicant disclosed catheter devices for implanting an artificial chordae line to repair a heart valve. The catheter devices of WO2016/042022 and WO2020/109596 include a mechanical gripper device for grasping the leaflet of the heart valve, with a leaflet anchor housed in the gripper. The leaflet anchor can be formed from a flexible material, such as nitinol, with a grapple hook shape in an unfolded configuration, and being able to deform elastically into the folded configuration, for example when constrained within a leaflet anchor channel in the gripper device. The hooks are straightened out when the leaflet anchor is in the folded configuration. When the leaflet is grasped by the gripper device then the leaflet anchor can be pushed out of the gripper to drive the hooks though the leaflet whilst they return elastically to the unfolded configuration, thereby securing the leaflet anchor in the leaflet. In each of WO2016/042022 and WO2020/109596, the disclosed embodiments generally require that the gripper arm contact the leaflet of the heart valve from a ventricular side. The leaflet anchor, deployed from the leaflet anchor channel in the gripper device, is therefore implanted into the leaflet from the ventricular side.
The devices described in WO2016/042022 and WO2020/109596 also use a papillary anchor with a broadly similar arrangement of foldable hooks. The papillary anchor is held within a tube of the catheter device in a folded configuration and can be pushed out of the tube with the hooks being driven through the papillary muscle whilst they return elastically to the unfolded configuration, thereby securing the papillary anchor to the muscle. The papillary anchor includes a locking ring acting as a locking mechanism for clamping an artificial chordae line when no force is applied. The locking ring maybe elastically deformed to release the line from the locking mechanism for adjustment of the length of the chordae line.
Whilst the devices of WO2016/042022 and WO2020/109596 provided significant advances in this field it has been found that further refinement of the design may be advantageous. The present disclosure relates to new features building on the design of the devices disclosed in WO2016/042022 and WO 2020/109596 in various respects.
It is therefore an objective of the discussed embodiments to provide an improved catheter device for repair of the heart by implanting an artificial chordae line.
Viewed from a first aspect of the present invention, there is provided a catheter device for repair of the heart by implanting an artificial chordae line, the catheter device comprising: a housing section extending from a distal end of the catheter device along the length of the catheter device toward a proximal end of the catheter device; a leaflet anchor for placement in a leaflet of a heart valve, wherein the leaflet anchor is arranged to be coupled to the artificial chordae line; and a leaflet anchor deployment mechanism for deploying the leaflet anchor to attach it to the leaflet of the heart, wherein the leaflet anchor deployment mechanism comprises a mechanical gripper device for grasping the leaflet of the heart valve, and a leaflet anchor tube for housing the leaflet anchor in a folded configuration; the gripper device and leaflet anchor being arranged such that when, in use, the gripper device grasps the leaflet, the leaflet anchor can be pushed out of a leaflet anchor tube to pierce the leaflet and form the leaflet anchor into an unfolded configuration so that hooked formations of the leaflet anchor can, in use, secure the leaflet anchor in the leaflet; wherein the mechanical gripper device includes a gripper arm rotatably coupled to a main body of the catheter device so that the gripper arm can rotate relative to the catheter device to move an outer end of the gripper arm away from the main body of the catheter device; and wherein the leaflet anchor tube is arranged to implant the leaflet anchor in the leaflet of the heart by piercing the leaflet from an atrial side of the leaflet.
This device allows a leaflet to be easily gripped and a new chord securely attached to the leaflet. There is no need for a complex procedure involving the use of vacuum and sutures as in WO 2008/101113. The mechanical gripper device can be opened and closed several times if required to release and re-engage the leaflet until it is in the desired position for the anchor to be placed. The piercing of the leaflet involves a single movement of the leaflet anchor, in contrast to the device of WO 2008/101113, where it is required to first pierce with a needle passing in one direction, and then pull through a suture in the other direction. Thus the device of the first aspect is simpler and more effective than the prior art device.
The previous catheter devices of WO2016/042022 and WO2020/109596 generally contemplated the implantation of the leaflet anchor in the leaflet of the heart by piercing the leaflet from a ventricular side of the leaflet, rather than an atrial side of the leaflet. However, the present applicant recognises that a catheter device which implants a leaflet anchor from an atrial side of the leaflet provides a number of advantages which may not be present when a leaflet anchor is implanted from a ventricular side of the leaflet of the heart.
When implanted from a ventricular side of the leaflet, the leaflet anchor may need to be located towards an edge of the leaflet in order to provide adequate support to the flailing leaflet. In contrast, when implanted from an atrial side of the leaflet, the leaflet anchor may provide adequate support to the edge of the leaflet when the leaflet anchor is implanted towards the edge of the leaflet, or towards an annulus of the leaflet.
The chosen location of implantation of the leaflet anchor may depend on a number of factors, and may be patient-specific. Implanting the leaflet anchor in an atrial side of the leaflet may provide a surgeon with greater flexibility in choosing where to implant the leaflet anchor, i.e. by being able to implant the leaflet anchor towards an edge of the leaflet, towards an annulus of the leaflet, or in between.
The tissue of the leaflet closer to the annulus, rather than towards an edge of the leaflet, may be less prone to experiencing trauma associated with the implantation of the leaflet anchor. The tissue towards the annulus of the leaflet may be thicker than that closer to the leaflet edge, for example. The tissue towards the annulus of the leaflet may be more able to withstand the tension associated with the artificial chordae line during the cardiac cycle, when the line is taut.
By implanting the leaflet anchor from the atrial side, the leaflet anchor may be able to be implanted closer towards an annulus of the leaflet of the heart whilst still providing adequate support to the edge of the leaflet.
When the artificial chordae line is used to prevent mitral regurgitation the line will generally be fixed at two ends, with one end located at/in the papillary muscle of the heart, and the other located at the leaflet anchor. If the leaflet anchor is therefore implanted in the leaflet from the ventricular side, the line will extend to the papillary muscle without providing any support to the edge of the leaflet, i.e. at a flailing end of the leaflet. However, when implanted in the leaflet from the atrial side, the line may extend along an atrial-side surface of the leaflet, and extend over the edge of the leaflet before descending into the ventricle to the location of implantation in the papillary muscle. As such, the line may provide support to the flailing edge of the leaflet with the anchor implanted towards the leaflet annulus. This may also better replicate the action of chordae tendineae located towards the edge of the leaflet of the heart valve.
The leaflet anchor may be arranged to be deployed such that the artificial chordae line will be in contact with an atrial side of the leaflet of the heart between the leaflet anchor and an edge of the leaflet of the heart valve.
When the leaflet anchor is implanted from the atrial side, it will be understood that the artificial chordae line may provide support to the flailing edge when implanted in the atrial side of the leaflet, given that the line will descend from the atrial side to the ventricular side through the mitral valve over an edge of the leaflet, when the line is implanted. This may be particularly beneficial when treating flailing leaflets.
The previous catheter devices of WO2016/042022 and WO2020/109596 may generally require precise implantation of the leaflet anchor in the leaflet to provide adequate support to the edge of the leaflet. As the leaflet anchor does not provide any additional support to the edge of the leaflet other than its own implantation, the location of implantation of the anchor determines how much support is provided to the edge of the leaflet. Accordingly, implantation of the leaflet anchor may need to be more precise to ensure adequate support to the edge of the leaflet.
However, due to the contact of the artificial chordae line with the edge of the leaflet when the leaflet anchor is implanted in the atrial side of the leaflet, the location of implantation of the leaflet anchor of the present invention need not be so precise, as additional support is provided to the edge of the leaflet regardless of whether the leaflet anchor is implanted towards the edge of the leaflet or towards the atrial annulus of the leaflet. This may result in more efficient implantation of the leaflet anchor, as movement of the leaflet during the cardiac cycle which may alter the location of implantation of the leaflet anchor will be of lesser detriment to the overall support provided by the leaflet anchor.
The artificial chordae line may have a varying cross-sectional area. The artificial chordae line may have a first cross-sectional area at an end distal to the leaflet anchor and/or configured to be located at/in the papillary muscle. The artificial chordae line may have a second cross-sectional area at an end proximal to and/or attached to the leaflet anchor.
The first cross-sectional area and the second cross-sectional area may be different. The second cross-sectional area may be a rectangular cross-sectional area. The second cross-sectional area may be an oval cross-sectional area. A major axis of the second cross-sectional area may be configured to be parallel to an atrial surface of the leaflet anchor. The second cross-sectional area may be greater than the first cross-sectional area. The first cross-sectional area may be circular.
By providing an artificial chordae line comprising a second cross-sectional area as discussed, the surface are of the artificial line which is in contact with the atrial side of the leaflet may be increased. The artificial chordae line may therefore provide a greater degree of support to the flailing leaflet when implanted.
The artificial chordae line may comprise a plurality of sutures. The plurality of sutures may increase an area of contact between the artificial chordae line and the atrial side of the leaflet, such that a greater degree of support is provided to the flailing leaflet by the artificial chordae line. Additionally, if one of the plurality of sutures fails, there is a redundancy introduced such that one or more of the plurality of sutures may still be successfully implanted.
The catheter device comprises a housing section extending from a distal end towards a proximal end of the catheter device. The most distal end of the catheter device may be where the artificial chordae line is generally implanted from, whilst the proximal end may be located at an opposite end of the catheter device. The catheter device may generally be inserted into the body in a direction aligned with the direction of extension from the proximal end to the distal end of the catheter device.
The leaflet anchor tube may take the form of a generally cylindrical channel sized to be slightly larger than the leaflet anchor in its folded configuration.
The leaflet anchor may be formed from an elastic material and to be arranged so that it assumes the unfolded configuration when no force is applied, and to be able to deform elastically into the folded configuration, for example when constrained within the leaflet anchor tube.
The leaflet anchor may be arranged to be deployed by pushing it out of an opening at the end of the leaflet anchor tube, wherein the opening is arranged to be in contact with an atrial side of the leaflet of the heart during deployment.
Placing the opening of the leaflet anchor tube in contact with the atrial side of the leaflet of the heart during deployment may facilitate the implantation of the leaflet anchor from the atrial side of the leaflet. For example, placing the opening in contact with the atrial side may ensure proper placement, location and deployment of the anchor as it assumes its unfolded configuration from its elastically folded configuration.
The leaflet anchor may be arranged to be pushed out of the leaflet anchor deployment mechanism from the proximal end of the catheter device toward the distal end of the catheter device.
The catheter device may comprise a linear-shaped rod for deployment of the leaflet anchor. The linear-shaped rod may be configured to push the leaflet anchor out of the leaflet anchor deployment mechanism.
The previous devices disclosed in WO2016/042022 and WO2020/109596 each taught a U-shaped rod for pushing the leaflet anchor out of the leaflet anchor deployment mechanism. The U-shaped rod was required in each of these prior art devices due to the leaflet anchor being deployed in a ventricular side of the leaflet, i.e. beneath the leaflet. However, for the present device, the leaflet anchor is configured to be implanted in an atrial side of the leaflet. Accordingly the leaflet is approached from above, and as such the leaflet anchor is deployed in a distal direction of the catheter device. In other words, the leaflet anchor is deployed in the same direction by which the catheter device approaches the leaflet of the heart.
As such, a linear rod may be used. The linear rod, being linear, may generally be easier to manufacture. The linear rod may also be easier to arrange in the catheter device, along any other number of wires, rods and the like for operating other components located in the distal end of the catheter device. As such the linear rod may ease manufacture of the catheter device, particularly when compared to previous U-shaped rod designs.
The catheter device may generally approach the location of implantation from an atrial side of the heart rather than a ventricular side of the heart due to known techniques of insertion of the catheter device into the heart. That is, on approach a distal end of the catheter device will be oriented towards the atrial side of the leaflet of the heart. As such, to facilitate deployment of the leaflet anchor in the atrial side of the leaflet (the surface of which will be oriented towards the proximal end of the catheter device), the leaflet anchor may be pushed out of the leaflet anchor deployment mechanism from the proximal end of the catheter device toward the distal end of the catheter device.
The leaflet anchor tube may be formed in the main body of the catheter device. The leaflet anchor tube may not be formed in the gripper device. An opening of the leaflet anchor tube may be located on a surface of the main body of the catheter device, such that the leaflet anchor may be deployed from the main body of the catheter device. The opening may be located such that the leaflet anchor is deployed from a circumferential surface and/or side of the catheter device.
The leaflet anchor tube may extend generally along a length of the main body of the catheter device. The leaflet anchor tube may also have a component of extension along a radius of the catheter device such that the leaflet anchor may be deployed from the catheter device from a position on the circumferential surface of the catheter device.
The present applicants have realised that forming the leaflet anchor tube in the main body of the catheter device, rather than in the gripper device, may provide a number of advantages not previously known. Thus whilst the following features are described in combination with the first aspect of the present invention, it will be understood that they may be novel and inventive in their own right.
In WO2020/109596 and WO2016/042022, a catheter device comprising a gripper arm, with the leaflet anchor tube formed in the gripper arm of the device, is contemplated. To be able to house the leaflet anchor tube within the gripper arm, the gripper arm is hence longer than the leaflet anchor in the prior art device. The extended length of the gripper arm to accommodate the leaflet anchor, and the location of deployment from the gripper arm, may effectively reduce the range of depth at which the leaflet anchor may be implanted in the leaflet.
When the leaflet anchor tube is formed in the main body of the catheter device, the gripper arm may be shorter in length than the leaflet anchor when in the folded configuration. This is possible as the leaflet anchor is not housed within the gripper arm. A shorter gripper arm may be able to grab the leaflet harder than a longer gripper arm when the same force is applied to the gripper arm. When the leaflet anchor is deployed in the leaflet at a location adjacent to a generally distal end of the gripper arm, the moment of the force associated with deploying the anchor may be reduced when using the shorter gripper arm. Thus the leaflet may be more firmly held in place during implantation of the anchor.
Additionally or alternatively, the length of the leaflet anchor may not be constrained by the length of the gripper arm. As such, when the leaflet anchor tube is formed in the main body of the catheter device, leaflet anchors longer than the length of the gripper arm may be utilised. Longer leaflet anchors may be capable of securing and/or supporting a larger portion of the leaflet of the heart, when implanted, compared to a shorter anchor.
The gripper arm may be arranged to meet an opening of the leaflet anchor tube. The leaflet anchor tube may be formed in the main body such that a surface of the gripper arm meets the opening of the leaflet anchor tube when it is held against the main body of the catheter. The opening of the leaflet anchor tube may meet a distal end of the gripper arm. The opening of the leaflet anchor tube may meet a surface of the gripper arm located towards the distal end of the gripper arm.
By arranging the gripper arm to meet an opening of the leaflet anchor tube, the leaflet anchor may be more reliably deployed at the desired location in the heart. For example, when the gripper arm grasps the leaflet, the leaflet may be held between the gripper arm and the leaflet anchor tube such that the leaflet anchor may be deployed into the leaflet at the grasped location. The gripper arm, located against a proximal side of the leaflet, may provide resistance against the leaflet as the anchor is deployed, such that the leaflet is suitably constrained during deployment.
Alternatively, the leaflet anchor tube may be housed within the gripper arm. An opening of the leaflet anchor tube may be at the end of the gripper arm and oriented towards a distal end of the catheter.
In this arrangement, it will be understood that the gripper arm may be hinged towards a proximal end of the catheter device, with a distal end of the gripper arm oriented towards a distal end of the catheter device. Thus, contrary to the gripper arms disclosed in WO2016/042022 and WO2020/109596, the gripper arm may be oriented such that the leaflet anchor is configured to be deployed in a distal direction of the catheter, rather than a proximal direction.
The opening of the leaflet anchor tube, located in the gripper arm, may be configured to meet a complementary surface of the main body of the catheter device. As such, when the leaflet is grasped by the gripper arm, the main body of the catheter device may provide resistance against the leaflet as the anchor is deployed, such that the leaflet is suitable constrained during deployment.
The gripper arm may be configured to grasp the leaflet such that the leaflet anchor tube is arranged to implant the leaflet anchor toward an annulus of the leaflet. The gripper arm may be configured in this way when the leaflet anchor tube is formed in the main body of the catheter device or the gripper arm.
For example, the gripper arm may grasp the leaflet such that an opening of the leaflet anchor tube is located towards the annulus of the leaflet. When the leaflet anchor tube is located in the main body of the catheter device, the gripper arm may grasp the leaflet from a ventricular side such that the distal end of the gripper arm is in contact with the leaflet at or towards a ventricular annulus of the leaflet, and the opening of the leaflet anchor tube is located at or towards the annulus of the leaflet on the atrial side. When the leaflet anchor tube is located in the gripper arm, the gripper arm may grasp the leaflet from an atrial side such that the distal end of the gripper arm is in contact with the leaflet at or towards the atrial annulus of the leaflet, and the opening of the leaflet anchor tube is hence located at or towards the atrial annulus of the leaflet.
The gripper arm may be additionally or alternatively configured to grasp the leaflet such that the leaflet anchor tube is arranged to implant the leaflet anchor toward an edge of the leaflet. The gripper arm may be configured in this way when the leaflet anchor tube is formed in the main body of the catheter device or the gripper arm.
The catheter device may comprise a hinge mechanism for the gripper arm, wherein the hinge mechanism is formed integrally with the material of the main body and rotates away from the main body by elastic deformation of that material.
A single wire may be provided to actuate the gripper arm by bending the hinge mechanism to rotate the end of the gripper arm away from the main body, with the gripper arm returning elastically to its rest position if no force is applied to the wire.
The gripper arm may be actuated with a single wire or with multiple wires. Advantages can be obtained if a hinge mechanism for the gripper arm is formed integrally with the material of the main body and rotates away from the main body by elastic deformation of that material. The gripper arm as well as the hinge mechanism may be formed integrally with the material of the main body. Alternatively, the gripper arm may include a separately formed arm section, such as a milled piece or a laser cut piece, with the separate arm section being attached to a hinge mechanism of the main body, for example by gluing or welding.
In some examples, the main body of the catheter device may be formed from an elastic metal such as nitinol with a hinge being provided by an elastic joint formed in the elastic metal. In that case a single wire can be used to elastically deform the gripper arm by bending an elastic joint with the main body to rotate the end of the gripper arm away from the main body, with the gripper arm returning elastically to its at rest position once no force is applied to the wire. An advantage of this is that the elastic force of the gripper arm can hold it in place against the main body of the catheter device when the force is released from the wire, without the need for a separate wire to be pulled to keep the grip on the leaflet secure. A second wire may however be implemented as a backup if it may be needed.
In other examples, the main body of the catheter device may be formed from a composite material, such as carbon or glass reinforced PEEK. The gripper arm may then be joined to the main body of the catheter device using a pin joint, the pin forming the axis of rotation of the gripper arm. The pin joint mentioned herein may be a revolute joint or a hinge joint, i.e. comprising intermeshing features with a pin or cylindrical member joining said members, the pin forming the axis of rotation for the joint.
Alternatively or in addition the gripper arm can be heat set in a “more than closed” configuration. This would allow the gripper arm to grasp tissue towards the main body of the device.
To form the gripper arm and the hinge integrally with the main body of the catheter device, the main body of the catheter may comprise an outer tube, with the gripper arm being formed as an articulated section of the outer tube. Several forms of slits and/or patterns can be formed in the tubing in order to provide a weakened hinge section allowing for bending without plastic deformation of the gripper arm.
In alternative arrangements a hinged gripper arm may be used. In that case the gripper arm may be milled, actuation in that case could be done with a spring for closing, and wire for opening, or vice versa, or with two wires (one for opening and one for closing). A pulley cut in the device can be used to redirect the pulling force from the pull wire.
The gripping surface of the gripper arm may be arranged to hold the leaflet with friction. For example the gripping surface may use a material with a high coefficient of friction and/or the gripping surface may have a texture or surface profile for increasing friction, such as a ridged or saw-toothed profile.
The housing section may be a two-part housing section. The catheter device may comprise: the two-part housing section extending from the distal end of the catheter device along the length of the catheter device toward the proximal end of the catheter device, the two-part housing section comprising a distal part at the distal end of the catheter device and a proximal part located on the proximal side of the distal part; the leaflet anchor deployment mechanism being at the proximal part of the housing section; a papillary anchor deployment mechanism at the distal part of the housing section for deployment of a papillary anchor for attachment to the papillary muscle, wherein the papillary anchor deployment mechanism is arranged for deployment of the papillary anchor by moving it outward in the distal direction relative to the distal part; and a flexible joint located between the proximal part and the distal part of the two-part housing section, wherein the flexible joint allows a centreline of the distal part to be angled relative to a centreline of the proximal part.
The two-part housing section may be arranged to be coincidentally placed between the papillary muscle and a leaflet of the heart during use of the catheter device.
The gripper arm may be provided in the proximal part of the two-part housing section and may be rotatably coupled to the catheter device. The gripper arm may be rotatably coupled via any of the above-discussed mechanisms.
The two-part housing section may be formed from two tubular sections in any suitable material, i.e. a medically appropriate material. Stainless steel or nitinol may be used. In the alternative, composite materials such as carbon-fibre or glass-fibre reinforced PEEK may be used. The catheter device may be formed via a combination of such materials with the materials for different parts of the device being selected dependent on the required characteristics of those parts. A material that allows Ultrasound to pass through and at the same time have sufficient strength is preferred, Carbon reinforced PEEK meets these demands well, and would also allow Injection moulding of the components which lowers manufacturing cost. Fibre reinforced plastic are normally not visible on X-ray, so strategically placed radiopaque markers in all components may be used to determine device component(s) position and orientation on X-ray relative to each other, as complementary information to ultrasound imaging.
The flexible joint may include a hinge element, for example with the distal part of the two-part housing section coupled to the proximal part via a pivoting mechanism or via an elastically deformable element. For example, the two parts of the housing section may be composite or metal parts coupled together by the hinge element.
The papillary anchor may be housed within the distal part of the housing section before its deployment. The papillary anchor may have a similar cross-section as the distal part of the housing section. For example, both may have a tubular form when the anchor is held in the distal part. As noted above the anchor may have a folded and an unfolded configuration allowing pins of the anchor to form into hooks within the body tissue during deployment of the papillary anchor. The papillary anchor deployment mechanism may take a similar form to that of WO2016/042022 or WO2020/109596.
In one example the papillary anchor deployment mechanism includes a first wire or rod for pushing the papillary anchor in the distal direction relative to the distal part of the two-part housing section. There may additionally be a second wire or rod for releasing the papillary anchor from the papillary anchor deployment mechanism in order to disengage the papillary anchor from the catheter device after it is implanted in the body tissue, i.e. the tissue of the papillary muscle and/or tissue adjacent to the papillary muscle.
The papillary anchor may have a chordae line attached to it, and may include a locking mechanism, such as a locking ring as in WO2016/042022 or in WO2020/109596, the locking mechanism being for clamping the chordae line when no force is applied to the locking mechanism. The locking ring may be able to be elastically deformed to release the line from the locking mechanism for adjustment of the length of the chordae line. The papillary anchor deployment mechanism may include a locking ring holder for holding the locking ring in its elastically deformed position, with the papillary anchor deployment mechanism being arranged to selectively withdraw the locking ring holder from the locking ring so that the chordae line can be locked in place after deployment of the papillary anchor and after any required adjustment of the length of the chordae line.
The leaflet anchor deployment mechanism may allow for retraction and repositioning of the leaflet anchor after deployment of the anchor into the leaflet via an ejector unit having a grasping device with a first configuration arranged to permit deployment of the leaflet anchor into the leaflet without disengagement of the leaflet anchor from the ejector unit, and a second configuration in which the leaflet anchor is reversibly released from the ejector unit; wherein in the first configuration the grasping device of the ejector unit grasps a proximal end of the leaflet anchor, whilst a distal end of the leaflet anchor is unimpeded by the grasping device to enable it to be implanted in the leaflet; and wherein in the second configuration the grasping device of the ejector unit is disengaged from the leaflet anchor.
The leaflet anchor may be retracted with a retraction tube/catheter, by pulling the chordae so the leaflet anchor folds inside the retraction tube. The retraction tube may be placed on top of a chordae only attached to the leaflet (with device removed) or a leaflet anchor placed in a poor location (partly engaged, free floating, entangled etc.). The retraction tube may be a deflectable shaft, with or without a flexible section on the tip (that allows the tip to find the leaflet anchor base, to allow retraction). Alternatively the retraction shaft may be a flexible tube that is arranged to engage with the base of the leaflet anchor. In either configuration a marker band in the tip is needed to confirm that the retraction tube is at the base of the leaflet anchor, prior to applying tension to the chordae, to prevent any unwanted damage to the implant or native tissue.
Another alternative to retract the leaflet anchor when it is free floating (not attached to anything) is to tension the chordae until the leaflet anchor can be folded inside the papillary anchor housing, either in the distal end or through an opening in the papillary anchor housing wall.
The leaflet anchor deployment mechanism include a leaflet anchor and/or a leaflet anchor deployment mechanism such as those disclosed in WO2016/042022 and WO2020/109596.
Viewed from a second aspect of the present invention, there is provided a method of use of the catheter device of the first aspect for repair of the heart by implanting an artificial chordae line, the method comprising: moving an outer end of the gripper arm away from the main body of the catheter device; grasping the leaflet between the gripper arm and the main body of the catheter device by moving the outer end of the gripper arm back towards the main body of the catheter device; and pushing the leaflet anchor out of the leaflet anchor tube to pierce the leaflet from an atrial side and form the leaflet anchor into an unfolded configuration so that hooked formations of the leaflet anchor secure the leaflet anchor in the leaflet.
Viewed from a third aspect of the present invention, there is provided a method of manufacture of the catheter device of the first aspect, the method comprising forming the main body of the catheter device from an elastic material. The method may comprise forming the leaflet anchor tube in the main body of the catheter device. The method may comprise forming a hinge of the gripper arm integrally with the main body of the catheter device via cutting of an elastic metal tube. The method may include forming the entirety of the gripper arm, including the hinge, integrally with the main body. It is considered to offer particular benefits to be able to form the device of the first aspect in this way, although it should be noted that other manufacturing methods may be used as discussed above. A nitinol tube may be used and/or the cutting step may use laser cutting. The laser cut tube may be electropolished after cutting in order to remove any sharp edges.
Certain example embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings in which:
The catheter devices presented here are proposed for non-surgical (endovascular) insertion of mitral chords to address mitral regurgitation caused by prolapse of a leaflet 12 of the valve. The Figures show different forms of catheter device 2 for this purpose, but it will be understood that the general principles are the same for each device in terms of implantation of a leaflet anchor 10 and a papillary anchor 9 in order to insert one or more artificial chordae lines 14 into the heart. The artificial chordae line(s) 14 are fixed to the prolapsing leaflet 12 and to the papillary muscle 26, thereby recreating a normal anatomy. A single catheter device 2 is used to place both a leaflet anchor 10 and a papillary anchor 9. The length of the chord 14 can be adjusted, again using the same catheter device 2, to eliminate the mitral regurgitation. Thus, the new device enables a single minimally invasive endovascular procedure to be used to repair the mitral valve, providing significant advantages compared to earlier systems requiring more invasive procedures and/or multiple operations.
It should be noted that although an endovascular approach is preferred and the device is hence capable of using this approach, the device could of course be used in different procedures, including more invasive procedures. Many of the advantages will remain, and it could be beneficial to use this device in situations where a more invasive procedure is merited. In addition, it is contemplated that, as discussed above, aspects of the design of the papillary anchor 9 could be used for an anchor for other purposes and this disclosure is not intended to be limited in this regard.
The catheter device 2 described in the following can be used to insert mitral chords through the venous system, starting in the femoral vein in the groin. A catheter is advanced to the right atrium. Approach to the left atrium is then gained by a so-called transseptal puncture whereafter a larger guidance catheter is advanced into the left atrium. The catheter device 2 for the heart repair is then introduced through the guiding catheter and into the left atrium.
X-ray and ultrasound guidance is used to position the device and, as explained in more detail below, the mitral leaflet 12 is grabbed and an artificial chordae line 14 is attached using a self-expandable leaflet anchor 10. The artificial chordae line 14 is then attached to the papillary muscle 26, using a, papillary anchor 9. The chord length can now be adjusted to eliminate any mitral regurgitation. Excess chord is then cut and all catheters are withdrawn. Echo and Doppler imaging is used to perform the procedure and monitor the result. The successful use of this endovascular technique will drastically reduce the invasiveness, complications and cost of mitral valve repair.
More detail on the structure and function of the device is set out below with reference to the Figures. The procedure of using one form of the device can be summarised as follows:
The leaflet anchor 10 is connected to an artificial chordae line 14, which can sit inside a narrow channel that goes along the surface of the first gripper arm 30 (as shown in
The two-part housing section, with the gripper housing (proximal part) 4 and papillary anchor housing (distal part) 8 might be approximately 6-7 mm in diameter, and approximately 30 mm in length.
A ridged surface on the gripper arm(s) 30, 32 may be provided to help it grip the leaflet 12. 3D ultrasound and/or other available sources can be used to confirm that the gripper mechanism 6 has grasped the correct part of the leaflet 12.
The gripper mechanism 6 can be opened and closed as many times as needed to grasp the right part of the leaflet 12. The opening and closing may be facilitated by a system allowing for one wire to pull the gripper mechanism 6 open, and one to pull it closed. Different arrangements of wires and/or rods may be used to control the example with two gripper arms 30, 32, as discussed above. Once the position of the gripper mechanism 6 is confirmed then the leaflet anchor 10 can be pushed out of the end of the leaflet anchor tube 38, such as by pulling a wire in the other end of the catheter.
As noted above, an ejector unit 36 may be used as shown in
In the first configuration the grasping device arranged to permit deployment of the leaflet anchor 10 into the leaflet 12 without disengagement of the leaflet anchor 10 from the ejector unit 36. Thus, the grasping device 50, which in this example comprises two grappling hooks 50 as shown, grips the leaflet anchor 10 and can advance along the leaflet anchor tube 38 from the fully stowed position as in
The grasping device 50 moves into the second configuration when the constraint from the leaflet anchor tube 38 is no longer present, for example when the grappling hooks 50 move beyond the end of the tube as shown in
If the physician is not satisfied by the connection during the testing (for example, if there is too much movement of the anchor 10 and/or not enough resistance to force on the line) then the leaflet anchor 10 can be retracted and placed in another location. If the grasping device 50 did not change from the first configuration during this test then the latter procedure may be carried out by reversing the deployment of the ejector unit 36 and leaflet anchor 10, for example by drawing those parts back into the leaflet anchor deployment mechanism. If the second configuration was used before it was determined that the connection of the anchor was not adequate then to retract the anchor 10 the ejector unit 36 should be first moved back to the first configuration so that the grasping device 50 reengages with the leaflet anchor 10, and then after that the deployment of the ejector unit 36 and leaflet anchor 12 is reversed, for example by drawing those parts back into the leaflet anchor tube 38.
A groove 52 is provided in a wall of the leaflet anchor tube 38 for guiding the ejector unit 36. The groove 52 ensures that the ejector unit 36 remains a single orientation relative to the tube 38 while it is moved along the tube. The groove 52 can set maximum limits on the range of movement of the ejector unit 36 and thus may prevent it from going too far in either direction, out of or into the leaflet anchor tube 38. The ejector unit 36 has a guide pin 56 for engagement with the groove 52. A narrowing 54 in the groove 52 is provided to act as an indicator to let the operator know when the ejector unit 36 has reached a certain position. The size of the guide pin 56 and the width of the narrowing 54 are set so that engagement of the pin 56 with the narrowing 54 in the groove 52 will require an increased force before further movement can be made, thus providing tactile feedback to the operating physician.
The leaflet anchor deployment mechanism of
In the example shown, the line pusher 58 transitions from a constrained state to a non-constrained state and moves radially outward to push the line 14 out, with this radially outward movement being permitted and the line pusher released once a constraint from the leaflet anchor 10 is removed. The line pusher 58 is an arm that extends axially forward from the ejector unit toward the leaflet anchor 10 and radially outward of the leaflet anchor tube 38 when the arm is at rest with no forces applied. Prior to deployment of the leaflet anchor 10 the arm of the line pusher 58 is bent elastically to place its distal end within the leaflet anchor 10, as shown in
With the leaflet anchor 10 implanted in the leaflet 12 the papillary anchor housing 8 at the end of the treatment catheter is then placed onto the papillary muscle 26. With the use of a flexible and extendable joint 34 this may be done as shown in
When the distal end of the distal part 8 meets the body tissue, and as further force is applied the counterforce from the body tissue eventually surpasses the forces holding the papillary anchor 9 in place, at this point tissue is pushed flat below the base of the distal part 8 giving a maximal chance of placing all pins 62 of the papillary anchor 9 correctly in tissue, and force can be applied to the papillary anchor 9 so that the ends of the pins 62 then move beyond the distal end of the distal part 8 to meet the body tissue. This may be done via additional force on the papillary anchor 9 from rods or wires 60 or extending the adjustment catheter 21, or it may be done through a pre-tension on the papillary anchor 9 (or friction between the adjustment catheter 21 and the distal part 8) that is held by friction with the distal part until the forces from the body tissue on the distal part 8 changes the balance of forces with the friction sufficiently so that the papillary anchor 9 ejects in a way similar to a paper stapler. As the papillary anchor 9 is ejected the pins 62 fold out and form into the hook shape of the unconstrained papillary anchor 9 to thereby engage with the body tissue 26. At this point the connection can be pull tested by operator, and/or visually confirmed on x-ray and/or ultrasound. If the connection is not satisfactory, the papillary anchor 9 can be pulled back into the distal part 8 and re-placed to attempt an improved coupling of the anchor 9 with the body tissue 26.
When the correct length is confirmed then the device is disengaged from the papillary anchor 9. This process also locks the artificial chordae line 14 in place and cuts off any excess, which is retained in the catheter and withdrawn from the body when the catheter is removed. A locking segment 28 of the papillary anchor 9 is held open by the cutting piece (not shown). The locking segment 28 is a band of the papillary anchor 9 that can be flexed to open a gap for the artificial chordae line 14 to pass through. In the natural shape of the papillary anchor 9, when no force is applied, this locking segment 28 fits closely with the remainder of the anchor 9 and so it will hold the artificial chordae line 14 in place. The locking segment 28 is held open until the artificial chordae line 14 is the correct length. The cutting piece cuts the artificial chordae line 14, which is pulled against the blade when the adjustment process is completed.
The catheter device 2 disclosed in each of WO2016/042022 and WO2020/109596 implants the leaflet anchor 10 from a ventricular side of the leaflet 12. As shown in
However, there may be situations in which it is advantageous to implant a leaflet anchor 110, and hence an artificial chordae line 114, from an atrial side of the leaflet 12. For example, as can be seen in
Implanting the leaflet anchor 10 from a ventricular side of the leaflet 12 also requires a more precise placement of the leaflet anchor 10. As there is no additional support provided to the edge 13 of the leaflet 12, the placement of the leaflet anchor 10 will determine to what extent the edge 13 of the leaflet 12 is supported and/or secured by the leaflet anchor 12. In contrast, the placement of a leaflet anchor 110 implanted from the atrial side of the leaflet 12 can be less precise, since the artificial chordae line 114 will provide additional support to the edge 13 of the leaflet 12 as it passes into the ventricle from the atrium of the heart.
The present invention provides a modified catheter device 102 capable of implanting a leaflet anchor 110 from an atrial side of the leaflet 12, as will now be described in detail.
The artificial chordae line 114 can comprise regions of varying cross-sectional area along its length. By increasing the cross-sectional area of the artificial chordae line 114 in certain sections, the artificial chordae line 114 can have an increased area of contact with the leaflet 12 of the heart. As such the force applied by the artificial chordae line 114 to the leaflet 12 may be more evenly distributed, and any pinching of the leaflet 12 which the artificial chordae line 114 may cause can be avoided.
The artificial chordae line 114 comprises a flattened cross-section proximal to the leaflet 12, i.e. such that a major axis of the cross-sectional area of the artificial chordae line 114 lies parallel to the surface of the leaflet 12. In alternative arrangements, the artificial chordae line 114 can be formed of a plurality of sutures, such that an area of contact between the artificial chordae line 114 and the atrial surface of the leaflet 12 is increased.
To implant the leaflet anchor 110 in the leaflet 12 of the heart from an atrial side, a leaflet anchor deployment mechanism and a gripper housing 106 of the catheter device 102 are arranged as shown in either
In both of the arrangements as shown in
In both of the arrangements shown in
The catheter devices taught in each of WO2016/042022 and WO2020/109596 used a U-rod to deploy the leaflet anchor. However, the catheter device 102 employs a linear rod to deploy the leaflet anchor 110. The linear rod will extend from a proximal end of the catheter device 102 and into the leaflet anchor tube 138, such that the leaflet anchor 110 can be deployed into the atrial side of the leaflet 12. The linear rod deploys the leaflet anchor 110 by pushing the leaflet anchor 110 out of the distally-facing opening of the leaflet anchor tube 138, using the end of the linear rod located in the leaflet anchor tube 138. The linear rod is flexible so that it can curve or bend, e.g. from the main body of the catheter device 102 shown in
Whilst the following features will be discussed in relation to the catheter device 102 as discussed in relation to
The gripper lever 132 is fixed at an end adjacent to where the gripper arm 130 is rotated from. The other end of the gripper lever 132 is free to move relative to the main body of the catheter device 102. The free end of the gripper lever 132 is attached to a wire or rod 134 which runs through the main body of the catheter device 102 and pushes the free end of the gripper lever 132. When pushed, the rod 134 therefore actuates the gripper lever 132 such that it is in a deployed configuration. In the deployed configuration, free end of the gripper lever 132 is arranged to meet the gripper arm 130. Thus, when in use, the leaflet 12 can be grasped between the gripper arm 130 and the gripper lever 132.
The combined grasping action of the gripper arm 130 and the gripper lever 132 can help ensure that the leaflet 12 is correctly grasped. The gripper arm 130 can be opened so that a gripping surface 136 of the gripper arm 130 meets the leaflet 12. Without additional support the leaflet 12 may move away from the gripper arm 130 as the gripper arm 130 is closed, due to the motion of the leaflet 12 during the cardiac cycle. However, the present arrangement of the gripper device 106 deploys the gripper lever 132 before the gripper arm 130 is closed. The leaflet 12 is therefore secured between the gripper lever 132 and the gripper arm 130 before the gripper arm 130 is closed. Finally, the gripper lever 132 and the gripper arm 130 can be withdrawn, with the leaflet 12 still secured, so that the leaflet 12 is secured in the desired position between the gripper arm 130 and the main body of the catheter device 102 when the gripper arm 130 is in the closed position. The leaflet anchor 110 can then be deployed in the desired location. Thus the provision of the gripper lever 132 may help increase the likelihood of successfully grasping the leaflet 12, and may ensure the correct positioning of the leaflet anchor 110 in the leaflet 12 during implantation of the leaflet anchor 110.
The gripper lever 132 can include a number of indentations or teeth along its length, which may assist in grasping the leaflet 12. The indentations or teeth increase the frictional hold of the gripper lever 132, such that the leaflet 12 is less likely to accidentally release from the gripper arm 130 and the gripper lever 132 when grasped. The gripper lever 132 is generally flexible so that it can be held at the end at which the gripper arm 130 is rotated from and can be pushed at the free end by the rod 134 to meet the gripper arm 130. The gripper lever 132 and the rod 134 may each be formed of a suitable elastic, yet tensile, material such as nitinol or stainless steel. The gripper lever 132 can be secured to the main body of the catheter device 102 and the rod 134 by welding or gluing the components together.
Whilst the gripper lever 132 has been described herein as being flush to the main body of the catheter device 102 when unconstrained, and contacting the gripping surface 136 when in the rod 134 is actuated, the gripper lever 132 could alternatively be flush to the gripping surface 136 of the gripper arm 130 when unconstrained. Accordingly, the gripper lever 132 will be opened away from the gripper arm 130 when the rod 134 pulls the free end of the gripper lever 132. The leaflet 12 can then be grasped between the open gripper lever 132 and the open gripper arm 130. Releasing the rod 134 will therefore cause the gripper lever 132 to return to its unconstrained position, and hence grasp the leaflet 12 between itself and the gripper arm 130. The gripper lever 132 being biased to grasp the leaflet 12 when no forces are applied may result in a more secure and/or reliable hold of the leaflet 12.
The tip 116 of the leaflet anchor 110 is shown in more detail in the close-up view of
Alternatively to the pins 162 of the leaflet anchor 110 extending in an elongate fashion adjacent to the leaflet 12, the pins 162 of the leaflet anchor 110 can be formed so that the tip 116 of the pins 162 is formed to point away from the leaflet 12.
Whilst multiple arrangements for the leaflet anchor 110 have been described in
Whilst the locking segment openings 129 discussed in relation to
At a distal end of the channel 190 is a chordae lock 192. The chordae lock 192 is disposed across the channel 190. The chordae lock 192 prevents natural chordae tendineae from getting entangled in the distal part 108 of the catheter device 102 during a procedure. To achieve this, the chordae lock 192 is biased such that the chordae lock 192 will deflect in an outwards direction from the circumferential surface of the distal part 108. However, the chordae lock 192 will not open inwards. Thus, when the artificial chordae line 114 is to be deployed, a force can be exerted from within the distal part 108 to open the chordae lock 192. However, when the natural chordae tendineae are proximate to the channel 190, they will be prevented from entering the channel by the chordae lock 192. As such entanglement of the natural chordae tendineae with the catheter device 102 is prevented, avoiding any trauma or damage to the chordae tendineae.
The chordae lock 192 can be housed within a dedicated lock channel 194. The lock channel 194 can be formed within a wall of the distal part 108 of the main body of the catheter device 102, such that the chordae lock 192 does not extend beyond the axial or radial extend of the main body of the catheter device 102. The chordae lock 192 can extend in an axial direction within the channel 194, before extending at a right-angle or substantially perpendicular angle to extend across the channel 190. The chordae lock 192 can also include a further bend at a proximal end of the chordae lock 192 to prevent the chordae lock 192 from being pulled out of the lock channel 194.
The chordae lock 192 can comprise a heat-set nitinol wire, which at rest is in a closed position across the channel 190. The nitinol wire can be arranged to elastically deform under the application of a force to open the chordae lock 192, before returning to its initial position upon withdrawal of the force.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018203.6 | Nov 2020 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/082045 | 11/17/2021 | WO |
