Patent Application
20220346805
The present invention relates to a patch deployment device for deploying a patch within a patient, in particular for deploying a patch to damaged tissue within a patient. The present invention further relates to a patch deployment system comprising the patch deployment device and the patch to be deployed and/or a funnel to be used with the patch deployment device. The present invention further relates to a method of applying a patch.
Positioning patches within the body is useful for a range of medical procedures. Patches can be used to deliver a therapeutic agent or they can be used for repairing damaged tissue. For example, it has recently been proposed to treat tears in the aorta by applying a patch over the tear, thus stopping flow of blood out of the tear and a possible aortic dissection resulting from the tear. In order to apply a patch in a minimally invasive way, it needs to be introduced into the body through as small an incision as possible and then successfully and securely applied to the affected area. The present invention addresses this need.
The present invention provides a patch deployment device, the device comprising a pusher wire having a proximal end and a distal end; a plurality of deployment wires, wherein each deployment wire; (i) has a first end and a second end, and the first end and second end are connected to the distal end of the pusher wire; and (ii) is configured to be in an unexpanded state when positioned and constrained within a catheter, and configured to self-expand into an expanded state when positioned beyond a distal end of the catheter and not constrained, wherein in the expanded state at least a portion of the wire is positioned within a plane that is substantially perpendicular to the longitudinal axis of the pusher wire and has an asymmetric form when viewed along a direction parallel to the longitudinal axis of the pusher wire.
This patch deployment device is able to adopt an unexpanded configuration for ease of insertion into the patient and then it is able to adopt an expanded position when at the location where the patch is to be applied. This minimises the trauma associated with applying a patch to an internal surface of a patient.
Further, each deployment wire extending between a first end and a second end, where the ends are connected to the distal end of the pusher wire, as well as having an asymmetric form in-between these ends, results in the deployment wire experiencing asymmetric forces when self-expanding. This results in a rotational aspect to the deployment of the device and so reduces the amount of headspace required around the distal end of the catheter when expanding the patch deployment device. In other words, the presence of an asymmetric loop-like structure results in asymmetric forces on the deployment wire and thus corresponding asymmetric movement when the deployment wires self-expand. This allows the deployment wires to move from the unexpanded state to the expanded state in an efficient manner. This means that the free volume required around the distal end of the catheter for the expansion to occur is reduced which makes the device easier to use within the confined spaces within the body of the patient.
The present invention further provides a patch deployment device, the device comprising a pusher wire having a proximal end and a distal end; a plurality of deployment wires, wherein each deployment wire: (i) has a first end and a second end, and the first end and the second end are connected to the distal end of the pusher wire; and (ii) is configured to be in an unexpanded state when positioned and constrained within a catheter, and configured to self-expand into an expanded state when positioned beyond a distal end of the catheter and not constrained; wherein at least a portion of each of the plurality of wires collectively form a patch applicator, wherein along a first direction that extends across the patch applicator when the plurality of deployment wires are in the expanded state, the distance of the patch applicator from a plane perpendicular to the longitudinal axis of the pusher wire is substantially constant; and along a second direction that extends across the patch applicator when the plurality of deployment wires are in the expanded state, the distance of the patch applicator from the plane perpendicular to the longitudinal axis of the pusher wire varies.
This patch deployment device is also able to adopt an unexpanded configuration for ease of insertion into the patient and then it is able to adopt an expanded position when at the location where the patch is to be applied. This minimises the trauma associated with applying a patch to an internal surface of a patient.
Further, the varying distance of the patch applicator surface from a reference plane allows tailoring of the patch deployment device for particular patch application scenarios. In particular, it allows a tailored amount of application pressure to be applied to regions of the patch when applying the patch to the patient and can provide improved adhesion of the patch to the patient.
In general, the patch deployment device is a device that is capable of being used with a patch, such as a therapeutic patch, and can be used to deploy this patch to the required site within the body of a patient.
The pusher wire is a wire that is capable of transmitting forces from its proximal end to its distal end. Such forces can be a pushing force or pulling force applied to the proximal end of the pusher wire by the user of the patch deployment device. A typical user of the patch deployment device could be the surgeon conducting a procedure involving the application of the patch from the patch deployment device.
As used herein, the terms “proximal” and “distal” are used relative to the user of the patch deployment device, i.e. the surgeon. In this way, the proximal part of a component is closer to the user than the distal part of the component when in use.
As noted above, the pusher wire has a proximal end and a distal end. These two ends represent the far extremities of the wire. The wire can be made of any suitable material for transmitting forces from one of its ends to the other. A possible material for the pusher wire is stainless steel. Another possible material for the pusher wire is a nickel-titanium alloy, such as Nitinol. Further possible materials for the pusher wire include aluminium or any suitable metallic alloy.
The patch deployment device has a plurality of deployment wires. Deployment wires are wires that are involved in the deployment action performed by the device. In particular, the deployment wires can be directly in contact with the patch that is being deployed. The deployment wires each have the form of a wire. That is, each of the deployment wires has an elongate form.
The deployment wires can be made of any material that is capable of self-expanding in the patient. In other words, any material that can be constrained within a catheter to then elastically expand into a neutral expanded state. Such materials include elastic, superelastic and shape-memory materials, such as some plastics, metallic alloys or composite materials.
Each of the plurality of deployment wires has a first end and a second end. The first end and the second end are the respective limits along the length of the wire. The first end and the second end of each deployment wire is connected to the distal end of the pusher wire. When referring to the respective ends being connected to other components, this is considered to encompass a portion at the end of the respective components being connected to a referenced component. In other words, a portion adjacent the first end and a portion adjacent the second end of the deployment wire are connected to a portion adjacent the distal end of the pusher wire. A portion adjacent to the end relates to a portion that extends no more than 10% of the total length of the wire away from the respective ends, preferably no more than 5%, even more preferably no more than 2%.
Since the first and the second end of each deployment wire is connected to the distal end of the pusher wire, each deployment wire has a loop-like form where it is connected at the first end at the distal end of the pusher wire, it then extends along its length away from the pusher wire and then returning to be connected at the second end to the distal end of the pusher wire. Having two ends of each deployment wire connected to the distal end of the pusher wire increases the stability of the deployment wire extending between the two ends and thus increases the stability of the patch application procedure where the deployment wire is used to apply a force to the patch against an application site in the patient in order to assist adhering the patch to the required application site.
The connection between the first end and the second end of the deployment wires and the distal end of the pusher wire can be achieved by any suitable means. The connection may be a connection provided by an adhesive. The deployment wires may be tied or welded, or soldered to the distal end of the pusher wire. The connection may be provided by a compression fitting such as a sleeve around the ends of the deployment wires at the distal end of the pusher wire. In this way, the sleeve is holding the ends of the pusher wire against the distal end of the pusher wire and thus securing them in place.
Each of the deployment wires is configured to be in an unexpanded state when positioned and constrained within a catheter. The deployment wires are configured to self-expand into an expanded state when positioned beyond a distal end of the catheter and not constrained. In this manner, the plurality of deployment wires can adopt a configuration so that they can fit within a catheter when constrained to do so, but then return to a neutral configuration when they are not constrained. In this way, the neutral state (i.e. a state in which the plurality of deployment wires are not experiencing any external forces, beyond those used to connect the ends of the deployment wires to the distal end of the pusher wire) is the so-called expanded state. In the expanded state, the plurality of deployment wires are in the configuration utilised for applying the patch to an application site within the patient. The term “unexpanded state” is used to contrast to the expanded state but refers to a state where the plurality of deployment wires experience an external constraining force such as by being contained by the inner walls of a catheter.
The ability of the deployment wires to self-expand into the expanded state is based on the deployment wires ability to be elastically deformed so as to be in the unexpanded state when constrained. The deployment wires can then elastically return to an expanded state when that external force is removed. In this way, the plurality of deployment wires which are positioned in the catheter in a constrained configuration can move to the expanded state when the plurality of deployment wires are pushed out of the catheter, i.e. beyond a distal end of the catheter, such that they are no longer constrained by external forces.
A catheter is a tube which can be used with the patch deployment device, within which the plurality of deployment wires and the pusher wire can be placed. The catheter may have any suitable form and may be a commercial catheter. In particular, the catheter should be made of a suitable material that can be used within the body of a patient. The catheter has an opening at its distal end so that the plurality of deployment wires may be pushed out of the catheter.
A plurality of catheters may be used with the patch deployment device. For example, the patch deployment device can be used with two catheters. In particular, the patch deployment device can be used with an inner catheter, referred to herein as an applier catheter, and an outer catheter, referred to herein as a guider catheter. The patch deployment device can be constrained within the applier catheter to be in its unexpanded state and can be deployed out of the applier catheter to be in its expanded state. The guider catheter can assist in moving the applier catheter to the required application location. The guider catheter may have a steerable tip to further assist with reaching the required application location.
When a deployment wire is in the unexpanded state it is configured such that the maximum distance of the deployment wire from the longitudinal axis of the pusher wire is less than the maximum distance in the expanded state. In this way, the deployment wires can fit within the catheter.
When the deployment wires are in an expanded state, each of the deployment wires may have an asymmetric form when viewed along a direction parallel to the longitudinal axis of the pusher wire. At least a portion of each of the deployment wires may be positioned within a plane that is substantially perpendicular to the longitudinal axis of the pusher wire. In this manner, the plurality of deployment wires form a surface substantially perpendicular to the longitudinal axis of the pusher wire which can then be used to press a patch onto a patch application site in the patient. Thus, this arrangement assists in placing the patch securely where it is required.
The portion of each deployment wire that is positioned within a plane that is substantially perpendicular to the longitudinal axis of the pusher wire may be at least 60% of the total length of the deployment wire, preferably at least 70%, more preferably at least 80%, even more preferably at least 90%. This will allow efficient use of the deployment wire as the patch applicator surface. The portion of each deployment wire that is positioned within a plane that is substantially perpendicular to the longitudinal axis of the pusher wire may be at least 30% or at least 40%.
A significant portion of each deployment wire may be arranged along the longitudinal axis of the pusher wire when the plurality of deployment wires are in the expanded state. In this way, this section of the deployment wire gives additional support to the patch applicator part of the plurality of deployment wires. The deployment wire being arranged along the longitudinal axis of the pusher wire encompasses the deployment wire being arranged around the projection of the pusher wire's longitudinal axis beyond the distal end of the pusher wire. This increases the distance between the end of the pusher wire and the patch applicator part of the plurality of deployment wires. In this case, this section of the deployment wires provides increased flexibility allowing the orientation of the patch applicator part to be changed without the need to bend the pusher wire. The deployment wire may be arranged along the longitudinal axis in a helical manner. The portion of each deployment wire that is arranged along the longitudinal axis of the pusher wire may be at least 10% of the total length of the deployment wire, preferably at least 20%, more preferably at least 30%. The portion of each deployment wire that is arranged along the longitudinal axis of the pusher wire may be less than 85%, preferably less than 70%, more preferably less than 60%. In particular, the portion of each deployment wire that is arranged along the longitudinal axis of the pusher wire may be between 30% and 60%. When referring to the portion of each deployment wire in this context, this relates to the combined portions of both ends of the deployment wires when the deployment wires form a loop, i.e. it is the total length of the first end that extends from the pusher wire and the second end that extends from the pusher wire. In terms of absolute length, the total length of each of the plurality of deployment wires that is arranged along the longitudinal axis of the pusher wire may be at least 20 mm, preferably at least 30 mm, most preferably at least 50 mm.
The longitudinal axis of the pusher wire is the axis that runs along the length of the pusher wire. The deployment wires are perpendicular to the longitudinal axis relative to the direction of the longitudinal axis when it intersects the plane containing the portion of the deployment wire referred to above. When the plane is not intersected by the pusher wire itself, the reference to the longitudinal axis of the pusher wire includes a projection of the longitudinal axis of the pusher wire beyond the distal end based on the direction of the longitudinal axis at the distal end of the pusher wire.
At least a portion of each deployment wire is positioned substantially within a plane that is substantially perpendicular to the longitudinal axis of the pusher wire when in the expanded state. In this manner, the deployment wires in this portion are planar to the extent that they provide a sufficiently flat surface for applying the patch to an application site. Further, this plane is substantially perpendicular to the longitudinal axis, in other words, it is within 10° of perpendicular to the longitudinal axis, preferably within 5°, preferably within 2°.
The portion of the deployment wire that is positioned substantially within a plane that is substantially perpendicular to the longitudinal axis of the pusher wire may also have an asymmetric form. In other words, all of the portion of the deployment wire that is positioned substantially within a plane that is substantially perpendicular to the longitudinal axis of the pusher wire may have an asymmetric form. This asymmetric form can be appreciated when viewing the configuration of the expanded deployment wire along a direction parallel to the longitudinal axis of the pusher wire. That is, the section of the longitudinal axis against which the perpendicular nature of the plane containing the portion of the wire is judged. When viewed in this direction the asymmetric form does not have any planes of symmetry or any axis of rotational symmetry. The asymmetric nature results in the asymmetric forces that result in a rotational aspect to the expansion of the deployment wire from the unexpanded state to the expanded state.
At least a portion of each of the plurality of wires collectively forms a patch applicator. These are the same portions that may also be in an asymmetric form as described herein. The term “patch applicator” is used to denote the combination of portions of the plurality of wires that form the surface that contacts the patch and assists in applying the patch to the patient when the plurality of wires are in the expanded state. The patch applicator may be considered to be the portions of the plurality of deployment wires that are not collectively parallel to the longitudinal axis of the pusher wire, i.e. all parts of the plurality of deployment wires that are not the portions of the deployment wires that collectively extend parallel to the pusher wire but instead collectively form a surface at an angle to the longitudinal axis of the pusher wire.
The relative prominence (in other words, the relative height) of the patch applicator of the patch deployment device may vary across the patch applicator when the plurality of wires are in the expanded state. This prominence can be defined relative to a reference plane. Such a reference plane may be the plane within which the majority of the patch applicator lies. Alternatively, the prominence may be defined relative to a plane perpendicular to the longitudinal axis of the pusher wire. In this way, the prominence is characterised by its form along the direction of application of the pushing force, i.e. parallel to the longitudinal axis of the pusher wire.
The presence of a variation in prominence, allows tailoring of the contact made when applying the patch in the body of the patient. This can optimise the patch application process and promote successful adhesion of the patch.
The distance of the patch applicator from a reference plane, e.g. a plane perpendicular to the longitudinal axis of the pusher wire, may be substantially constant along a first direction that extends across the patch applicator when the plurality of deployment wires are in the expanded state, i.e. the first direction extends from one outer edge of the patch applicator to an opposite outer edge of the patch applicator, and passes through the longitudinal axis of the pusher wire.
The distance of the patch applicator from a reference plane, e.g. a plane perpendicular to the longitudinal axis of the pusher wire, may vary along a second direction that extends across the patch applicator when the plurality of deployment wires are in the expanded state, i.e. the second direction extends from one outer edge of the patch applicator to an opposite outer edge of the patch applicator, and passes through the longitudinal axis of the pusher wire.
The combination of varying prominence along one direction and constant prominence along another allows tailoring of the contact force that the patch will experience when the patch is applied in the patient.
When referring to the distance of the patch applicator from a reference plane, this distance is the shortest distance from the plane as you move along the direction of interest. In other words, in relation to the first direction above, the patch applicator is at a constant distance from the plane as you move along the first direction across the patch applicator. In relation to the second direction above, the patch applicator is not at a constant distance from the plane as you move along the second direction across the patch applicator.
The first direction may be perpendicular to the second direction. This allows the application properties to be relatively altered between these two directions.
It is particularly preferred that the prominence may vary such that the prominence increases with increasing distance of the plurality of deployment wires from the longitudinal axis. In particular, along the second direction, the distance of the patch applicator from the reference plane, e.g. a plane perpendicular to the longitudinal axis of the pusher wire, may increase with increasing distance from the longitudinal axis of the pusher wire. This allows a particularly prominent outer region of the patch applicator, which can usefully tailor the application properties that are relevant to the outer edges of the patch. The outer edges of the patch can be the region of the patch that is most critical to retaining the patch at the desired location within the patient. The variation may be follow an elliptical path so that the rate of increase in distance also increases with distance from the longitudinal axis. This further ensures the relative prominence of the outer edge of the patch applicator.
The varied prominence of the patch applicator may be such that the patch applicator has a concave shape with respect to a point that is distal of the patch applicator, i.e. the concavity is directed towards the intended application site in the patient. This concavity can ensure that pressure is applied where it is most effectively required during the patch application process. Alternatively, the concavity may be with respect to a point that is proximal of the patch applicator.
The patch applicator may have a symmetrical profile in the sense that diametrically opposite points on the patch applicator are at the same distance from the reference plane. This can be true throughout the patch applicator ensuring the prominence profile has an axis of at least two-fold rotational symmetry extending through the surface of the patch applicator. This rotational axis is preferably parallel to the longitudinal axis of the pusher wire, in particular it is preferably coincident with the longitudinal axis of the pusher wire.
It is particularly preferred that the patch applicator has a symmetrical profile, is concave with respect to a point distal of the patch applicator, and the distance of the patch applicator from a plane perpendicular to the longitudinal axis of the pusher wire increases with increasing distance from the longitudinal axis of the pusher wire along a second direction, while being constant along a first direction. It is further preferred that the distance variation along the second direction follows an elliptical path.
When referring to an elliptical path, it is preferred that the semi-minor axis of the ellipse is coincident with the longitudinal axis of the pusher wire, resulting in a lower rate of increase in prominence near the longitudinal axis. The patch applicator may follow the path of the ellipse from the co-vertex of the ellipse at the longitudinal axis of the pusher wire along substantially the full length of the the semi-major axis to the vertex. The patch applicator only follows, at most, half of the ellipse so as to have an open concave shape. It does not follow the elliptical path beyond the vertex, where the elliptical path would return towards the semi-minor axis.
The varying prominence of the patch applicator may be defined relative to the reference plane and the distance of the patch applicator from this reference plane may vary by more than 1 mm, preferably more than 1.5 mm, even more preferably more than 2 mm, alternatively more than 2.5 mm. It may vary by less than 30 mm, preferably less than 25 mm, more preferably less than 22 mm, alternatively less than 20 mm. It may also vary by any combination of these limits such as between 1 mm and 20 mm, or between 1 mm and 25 mm etc.
The varying prominence can alternatively be characterised relative to the maximum diameter, D, of the plurality of deployment wires when in the expanded state. The varying prominence of the patch applicator may be defined relative to the reference plane, and the distance of the patch applicator from this reference plane may vary by more than 0.025 D, more than 0.05 D or more than 0.06 D. It may vary by less than 0.5 D, or less than 0.4 D, or less than 0.3 D, or less than 0.26 D. It may also vary by any combination of these limits such as between 0.05 D and 0.3 D.
When the patch applicator's prominence follows an elliptical path, the varying prominence can be characterised by the eccentricity of the elliptical path. The eccentricity is less than 1 and can be more than 0.7, preferably more than 0.8, even more preferably more than 0.85.
As noted above, the plurality of deployment wires can be in the unexpanded state within the catheter and then be in an expanded state when positioned beyond the distal end of the catheter and no longer constrained. The plurality of deployment wires may be moved within the catheter by moving the pusher wire. The pusher wire may be movably positioned within the catheter in order to achieve movement of the pusher wire relative to the catheter.
The catheter may be a steerable catheter. In this way, the distal end of the catheter may be directed relative to the rest of the catheter so as to more easily position the distal end of the catheter in relation to the proposed application site onto which the patch is intended to be deployed.
The size of the catheter, i.e. its outer diameter, is chosen to be suitable for containing the deployment device as well as being able to be used in the required medical application. The catheter may have a size given in French gauge of from 2 to 97, preferably 4 to 32 or 6 to 30, more preferably 12 to 14. The catheter may have a size of 18 Fr or less. The catheter may have a size of 12 Fr or greater. The catheter may have an inner diameter that is at least 1 less in terms of French gauge compared to its outer diameter. The catheter may have an inner diameter given in French gauge of from 1 to 96, preferably 3 to 31 or 5 to 29, more preferably 11 to 13.
One unit of French gauge is equivalent to ⅓ mm. Therefore, 3 French is equivalent to a diameter of 1 mm.
When two catheters are used, the inner catheter, also referred to as the applier catheter, may have the sizes mentioned above, while the outer catheter, also referred to as the guider catheter, may have an outer diameter size that is 2 or 4 more in terms of French gauge than the applier catheter's outer diameter. The inner diameter of the guider catheter may be at least 1 less in terms of French gauge than the outer diameter of the guider catheter. The guider catheter may have a size (outer diameter) given in French gauge of from 4 to 99, preferably 6 to 34, more preferably 14 to 18. The catheter may have an inner diameter that is at least 1 less in terms of French gauge compared to its outer diameter. The catheter may have an inner diameter given in French gauge of from 3 to 98, preferably 5 to 33, more preferably 13 to 17.
The catheters have a circular cross-sectional shape.
Each of the deployment wires of the plurality of deployment wires may have the same form in the expanded state. In other words, each of the deployment wires may be arranged into the same shape in the expanded state. Even though the deployment wires have the same shape they are not coincident and so will be positioned at different locations around the pusher wire. Each of the deployment wires having the same form contributes to the consistent behaviour when applying the patch to the required location.
The plurality of deployment wires may be arranged so as to be evenly distributed around the longitudinal axis of the pusher wire when in the expanded state. The even distribution of the pusher wires again contributes to the consistent performance in applying a patch to the required location regardless of the angular orientation of the deployment device. Evenly distributed means that each deployment wire of the plurality is positioned at regular angular intervals around the longitudinal axis of the pusher wire.
The asymmetric form of each deployment wire may comprise curved portions. In particular, the asymmetric form may comprise a first curved portion and a second curved portion wherein the first curved portion and the second curved portion are connected via a connecting portion. The connecting portion may also be curved.
The first curved portion may overlap the second curved portion in a circumferential direction around the longitudinal axis of the pusher wire. In other words, when a path is followed in a circumferential manner around the longitudinal axis of the pusher wire, where the path has a constant radial distance from the longitudinal axis of the pusher wire, it first passes through the first curved portion and then the second curved portion.
The first curved portion may be convex. A convex portion in this context is one which protrudes away from the centre of the shape. The second curved portion may be concave. A concave portion in this context is one that protrudes towards the centre of the shape. Reference to a shape here refers to the shape formed by the deployment wire. Having one concave portion and one convex portion joined by a connecting portion provides a crescent-like shape that requires a relatively small volume in order to move from the unexpanded state within a catheter to the expanded state outside of the catheter. The connecting portion may be the portion of deployment wire where the deployment wire transitions from being a concave shape to a convex shape.
The first curved portion may comprise a minimum radius of curvature that is less than the minimum radius of curvature of the second curved portion. In other words, at some point along the first curved portion there is a minimum radius of curvature and that value of radius of curvature is less than the point along the second curved portion that has a minimum radius of curvature for the second curved portion. Conversely, the first curved portion may comprise a minimum radius of curvature that is more than the minimum radius of curvature of the second curved portion. In other words, at some point along the first curved portion there is a minimum radius of curvature and that value of radius of curvature is more than the point along the second curved portion that has a minimum radius of curvature for the second curved portion. This increases the asymmetric nature of the deployment wire and this contributes to the asymmetric forces that are experienced when the deployment wire moves from the unexpanded to the expanded state, thus assisting an efficient deployment that requires less volume in order for the deployment to occur. In relation to the radius of curvature it could also be said that the first curved portion has a tighter curve than the second curved portion. Conversely, it could also be said that the second curved portion has a tighter curve than the first curved portion.
The plurality of deployment wires may be arranged such that there is overlap in a direction substantially parallel to the longitudinal axis of the pusher wire between different deployment wires. This can help increase the stability of the device in the expanded state when it is used to apply a patch to a required location. When there is a first curved portion and a second curved portion the first curved portion of one deployment wire may overlap the second curved portion of an adjacent deployment wire in a direction substantially parallel to the longitudinal axis of the pusher wire. Further, the first curved portion of one deployment wire may overlap the second curved portion of an adjacent deployment wire in a direction substantially parallel to the longitudinal axis of the pusher wire at a plurality of points, for example two points. Alternatively, or in addition, the first curved portion of one deployment wire may overlap the first curved portion of an adjacent deployment wire in a direction substantially parallel to the longitudinal axis of the pusher wire. Further, the first curved portion of one deployment wire may overlap the first curved portion of a plurality of adjacent deployment wires in a direction substantially parallel to the longitudinal axis of the pusher wire, for example, two adjacent deployment wires. Such overlap described herein can be true for all the deployment wires that are present so that each deployment wire is providing a further support to at least one other deployment wire.
Where the prominence of the patch applicator varies, the deployment wires that are the most prominent may overlap with adjacent deployment wires in a direction parallel to the longitudinal axis of the pusher wire such that the adjacent deployment wires are underneath the most prominent deployment wire when viewed from the direction in which the prominence extends. In addition, or alternatively, the deployment wires that are the least prominent may overlap with adjacent deployment wires in a direction parallel to the longitudinal axis of the pusher wire such that the adjacent deployment wires are on top of the least prominent deployment wire when viewed from the direction in which the prominence extends. In this manner, extra support is provided to the more prominent deployment wires increasing the stability of the patch deployment device.
The overlapping nature of the plurality of deployment wires may result in the plurality of deployment wires having an overall shape that is at least partially defined by each of the plurality of deployment wires. In addition, the plurality of deployment wires when in the expanded state may be arranged such that they collectively form a wire ring when viewed along the longitudinal axis of the pusher wire. In other words, a wire ring that goes around the longitudinal axis of the pusher wire can be discerned which comprises parts of the plurality of deployment wires. The plurality of deployment wires may, in combination, have the shape of a circle, i.e. the outer shape of the plurality of deployment wires is a circle when viewed along the longitudinal axis of the pusher wire. In this case, the wire ring may be the outer perimeter of the plurality of deployment wires. This provides consistent support to the patch around the perimeter of the plurality of deployment wires.
The plurality of deployment wires, when in the expanded state, may collectively form a ring and a further ring that is substantially concentric with the ring referred to above. They can both be of a substantially circular shape. This provides two ring regions of consistent support, an inner ring and an outer ring. The first ring may be used to apply a consistent force to the outer region of a patch. When this is the inner ring, the further ring is the outer, concentric ring and may be used to apply a consistent force to the area of the patient around where the patch is being applied. This helps restrain this area to aid adhesion of the patch. When an inner ring and an outer ring are present, the features described herein may apply just to the portions of the plurality of deployment wires that are part of, and within, the inner ring. For example, the reference herein to the maximum diameter of the plurality of deployment wires in the expanded state can apply just to the maximum diameter of the inner ring. In this situation, the outer ring can extend at least 2 mm beyond the inner ring, preferably at least 5 mm beyond, more preferably at least 7 mm beyond, most preferably at least 10 mm beyond. Alternatively and preferably, the features described herein may apply to the whole of the plurality of deployment wires. In relation to maximum diameter, it is preferred that when an inner ring and outer ring are present, the outer ring has a maximum diameter of 70 mm or less, more preferably 50 mm or less. When the outer ring is also present, it is preferred that the inner ring has a maximum diameter of 50 mm or less, more preferably 30 mm or less.
It is especially preferred that the plurality of deployment wires are formed from Nitinol. Nitinol is a nickel-titanium alloy that can exhibit shape memory and superelastic properties. The superelastic properties are particularly beneficial to the present invention since they allow the extensive deformation to elastically occur between the unexpanded state and the expanded state. This contributes to the ability of the deployment device to be contained within a small catheter. However, any material with sufficient elastic properties may be used with the present invention.
When Nitinol is used it is preferred that it exhibits its superelastic properties at body temperature. In this way, the deployment device will be exhibiting superelastic properties when used within the body. In order to ensure superelastic properties are exhibited the austenite finish temperature of the Nitinol should be below body temperature, i.e. below 37° C. It is particularly preferred that the Nitinol has an austenite finish temperature of 28° C. or less. The austenite finish temperature may be −20° C. or greater, or −15° C. or greater. Typically, the austenite finish temperature is between 18° C. and 28° C. In any case, the composition of the Nitinol should be chosen such that the Nitinol exhibits the required superelastic properties when used within the body.
The plurality of deployment wires may comprise any number of deployment wires that are suitable for the application. The plurality of deployment wires may comprise 20 deployment wires or fewer, 16 deployment wires or fewer, more preferably 12 deployment wires or fewer. A lower number of deployment wires makes it easier for the device to fit into smaller catheters.
The plurality of deployment wires may comprise two deployment wires or more, preferably four deployment wires or more, preferably 6 deployment wires or more. An increasing number of deployment wires improves the stability of the device when applying a patch to the required location.
A particularly favourable combination is to utilise eight deployment wires.
The plurality of deployment wires may each have a diameter of 0.127 mm (0.005 inches) or more. This assists the device in having a good level of stability when applying the patch to the required location.
The plurality of deployment wires may each have a diameter of 0.508 mm (0.02 inches) or less. This assists in the deployment device in having less internal forces when moving from the unexpanded state to the expanded state and being contained within a small catheter.
The diameter of each of the deployment wires relates to the maximum diameter of a cross-section of the wire that is perpendicular to the longitudinal axis of the wire. It is particularly preferred that the cross-section of the wire is circular.
The plurality of deployment wires may have a maximum diameter of 70 mm or less, preferably 60 mm or less, more preferably 50 mm or less, or 35 mm or less, when each deployment wire of the plurality of deployment wires is in the expanded state. The plurality of deployment wires may have a maximum diameter of 5 mm or more when each deployment wire of the plurality of deployment wires is in the expanded state. A maximum diameter is the greatest diameter that spans across the centre of the plurality of deployment wires. The centre of the plurality of deployment wires is where the pusher wire is located. In general, the maximum diameter may be anything suitable for the required application, but 30 mm to 35 mm has been found to be particularly effective when used for applying patches to the required location.
The patch deployment device may be provided with the patch releasably attached to the plurality of deployment wires. Alternatively, the patch deployment device may be provided with the patch separate for attachment ahead of use. In any case, the releasable attachment of the patch to the plurality of deployment wires means that is can be released from the deployment wires when positioned and secured at the required location in the patient. The patch can be releasably attached to the plurality of deployment wires by using a bioadhesive. Such a bioadhesive may lose adhesion when positioned in the body and thus facilitate its removal from the deployment wires.
The patch may be attached to the plurality of deployment wires by a single thread, wherein the single thread is threaded through a plurality of loops associated with the patch, wherein both ends of the thread extend to the proximal end of the pusher wire. In this way, the user of the patch deployment device can hold both ends of the thread. By holding both ends of the thread, the patch is retained on the deployment wires. When the patch needs to be released, the user can let go of one end of the thread and pull the other end thus unthreading the wire through the loops and removing the means by which the patch was retained on the deployment wire assisting its release from the plurality of the deployment wires. The loops associated with the patch may be holes that are present in the patch. Instead of being weaved within the deployment wires, there can be a plurality of loops attached to the deployment wires through which the single thread is threaded. The thread may be a suture thread.
The patch deployment device may be inserted into the catheter with the assistance of a funnel. The funnel may be attached to the distal end of the catheter so that its narrowest end is closest to the distal end of the catheter, and it flares outwards in the distal direction. The deployment wires can then be drawn through the funnel such that they are gradually moved towards the unexpanded state from the expanded state by the decreasing diameter of the funnel. In this way, the funnel can contribute to the efficient packing of the deployment wires in the catheter. The funnel may be made from any suitable material including any suitable plastic.
Any suitable patch may be used as part of the patch deployment device, for example the patch may be bioabsorbable. The patch may be made from a polymeric material. The patch may be any suitable shape. However, an advantageous shape is circular shape so that it may be deployed at any angular orientation. Another advantageous shape is a rectangular shape, since patches are commonly deployed over linear tears, which can be efficiently covered by rectangular patches. The present invention is particularly suitable for use with the patch described in PCT application number PCT/EP2019/056358, which is incorporated herein by reference.
The present invention further provides a patch deployment system comprising the patch deployment device described herein and a separately provided patch and/or funnel and/or catheter.
The present invention also provides a method of applying a patch comprising the following steps: (i) providing the patch deployment device as described herein with a plurality of deployment wires in the unexpanded state within a catheter; (ii) inserting the catheter into a patient so as to position the distal end of the catheter at a patch application site; (iii) moving the pusher wire to move the plurality of deployment wires from the unexpanded state within the catheter to the expanded state beyond the distal end of the catheter; (iii) applying the patch to the patch application site; (iv) releasing the patch from the plurality of deployment wires; (v) moving the pusher wire to move the plurality of deployment wires from the expanded state to the unexpanded state; and (vi) removing the catheter from the patient.
This approach utilising the patch deployment device of the present invention advantageously requires a relatively small amount of headspace around the distal end of the catheter for deploying the patch deployment device within the patient and also suitably supports the patch when applying it to the patch application site. The patch application site can be any site in the patient that requires the application of a patch. The present invention is particularly suited for applying a patch to a tear within the aorta of the patient with a patch that is suitable for repairing that tear.
Further, when using a patch deployment device that has an increasing distance from a reference plane as you move away from the longitudinal axis, such as to provide a concave patch applicator with respect to a point distal to the patch applicator, it is preferred that the direction along which the distance increases is aligned with the direction of blood flow and/or the longitudinal direction of the curvature of the wall. This provides a good contact for the outer region of the patch at locations that may otherwise be more vulnerable to adhesive failure.
The present invention will now be described with reference to the following figures.
The expanded configuration of the deployment wires 8 is shown in greater detail in
A procedure utilising the patch deployment device will now be described in relation to
The outer circle is a wire ring that has been collectively formed by plurality of deployment wires, specifically it has been formed collectively by the first curved portion 48 of each deployment wire. In addition, there is an inner wire ring that is collectively formed by the second curved portion 50 of each of the plurality of deployment wires. In this way, the overall arrangement provides two rings that can provide a continuous circumferential support. A patch can then be applied using the inner ring to support the outer periphery of a circular patch, while the outer ring can apply continuous pressure to the area around the patch application site, to hold the site in position during the application process and so improve the adhesion of the patch.
An experiment was conducted to assess the effect of the patch applicator of
The present invention has been described with reference to specific embodiments. However, the invention is not limited by these specific embodiments and encompasses any subject matter within the scope of the following claims.
The following list of embodiments forms part of the description.
A further list of embodiments that forms part of the description is given below
| Number | Date | Country | Kind |
|---|---|---|---|
| 19382814.2 | Sep 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/076624 | 9/23/2020 | WO |
