Endovascular catheter and thrombectomy or atherectomy system having an endovascular catheter

Abstract

The present invention relates to an endovascular catheter for use in atherectomy or thrombectomy, comprising a catheter body having a proximal and a distal end, the catheter body extending in a longitudinal direction of the catheter, and a tissue ablation means positioned at the distal end of the catheter, the tissue ablation means being arranged for ablating thrombotic tissue adhering to the inside of a vessel wall, the catheter body comprising a reorientation means comprising at least one shape memory element for reorienting the distal end of the catheter, the reorientation means being arranged so that, upon selective activation of the shape memory element, the distal end of the catheter can be reoriented in at least two different directions.

Description

[0001] ENDOVASCULAR CATHETER AND THROMBECTOMY OR ATHERECTOMY SYSTEM HAVING AN ENDOVASCULAR CATHETER

[0002] TECHNICAL FIELD

[0003] The present disclosure is directed at endovascular catheters and thrombectomy and atherectomy systems having such catheters .

[0004] During thrombectomy and / or atherectomy procedures , a catheter is introduced into a vessel to aspirate and / or macerate occlusive material . Such catheters typically have a rotor at a distal end which rotates relative to a catheter body . The rotatable part may be configured to promote removal of occlusions and / or calci fications that adhere to a vessel wal l during a procedure .

[0005] During such a procedure , the catheter is advanced through the often tortuous vasculature of a patient to a target site where material is to be ablated . Once it reaches that site , an ablation means arranged at the distal tip removes material on the inside of the blood vessel .

[0006] SUMMARY

[0007] In view of the existing technology, it was noticed that it would be desirable to extend the range over which thrombectomy and atherectomy devices ablate material . Generally speaking, with atherectomy / thrombectomy catheters , their function of a "drill" through adhering material tends to mean that mostly, thrombotic tissue extending to the center of the blood vessel is ablated . There will , however, be material adhering to the sides of the blood vessel which also ought to be removed . However, with the conventional technology, it becomes di f ficult to reach - and thus ablate - such material .

[0008] Thus , the range over which adhering material can be ablated is generally limited to about the diameter of the distal tip of the catheter . Accordingly, i f one wants to increase the range over which one can ablate material , the conventional technology suggests increasing the diameter of the distal tip . On the other hand, advancing a catheter having a wider distal tip to the target site through the often tortuous and narrow vasculature of a patient proves di f ficult and may even be impossible . It would thus be desirable to increase the range over which one can ablate adhering tissue without having to signi ficantly increase the diameter of the distal end of the catheter .

[0009] It would also be desirable to make it easier for a surgeon using an atherectomy / thrombectomy device to reach vascular occlusions arranged on the entire circumference of a blood vessel without having to twist the catheter . As it presently stands , twisting the catheter to reach those positions is often cumbersome , so that it would be desirable to make a thrombectomy / atherectomy procedure less awkward to perform .

[0010] The present disclosure has been conceived in view of the above challenges and aims to alleviate or even solve at least some of them . The present disclosure aims at providing an endovascular catheter that makes it easier for a surgeon to reach vascular occlusions and calci fications arranged at di f ferent circumferential positions inside a blood vessel .

[0011] Embodiments are directed to an endovascular catheter for use in atherectomy and thrombectomy . Such catheters can, in embodiments , be used for ablating calci fied tissue arranged at the walls of a blood vessel .

[0012] A catheter body of an endovascular catheter has a proximal end and a distal end, with the catheter body extending in a longitudinal direction of the catheter . The proximal end of the catheter body is that end of the catheter body that will , when in use , be closest to a surgeon whilst the distal end of the catheter body is , during use , inserted into a patient ' s vasculature . The endovascular catheter furthermore comprises a tissue ablation means that is positioned at the distal end of the catheter and is arranged for ablating thrombotic tissue adhering to the inside of the vessel wall . In embodiments , this tissue ablation means can comprise a rotor that is rotatable relative to a stationary part of the catheter and that can be rotated to remove thrombotic tissue .

[0013] The endovascular catheter comprises a reorientation means which comprises at least one shape memory element . This reorientation means is arranged so that , upon selective activation of the reorientation means , the distal end of the catheter can be reoriented in at least two di f ferent directions . In embodiments , those two di f ferent directions mean that relative to the catheter body, the distal end will be pointing in two di f ferent directions , which could mean that the distal end is inclined to di f ferent circumferential positions or is inclined at a di f ferent angle of inclination relative to the longitudinal direction of the catheter body . By this feature , by means of di f ferently activating the reorientation means , the shape memory element will cause a change in the orientation of the distal end to thus allow the distal end to be bent relative to the longitudinal direction of the catheter whilst pointing at di f ferent positions inside the blood vessel . As a result , the range over which thrombotic tissue can be ablated is increased . Further, this increase in range is achieved without signi ficantly increasing the crosssection of the distal end of the catheter . In addition, the change in direction can be achieved without extensive manipulations of the catheter by a surgeon simply by di f ferently activating the reorientation means . Further, using shape memory elements has the advantage of avoiding a complicated set up at the distal end for reorienting the distal end of the catheter . This also reduces the crosssection of the distal end . This change in shape can also help in reaching the target site inside a patient ' s vasculature .

[0014] Optionally, the reorientation means comprises at least two , further optionally at least four shape memory elements arranged at di f ferent locations along the catheter body so that they can be individually activated to reorient the distal end of the catheter . Thereby, by having individually activatable shape memory elements , the surgeon can, should they wish to reorient the distal end of the catheter to thereby ablate thrombotic tissue at di f ferent locations inside a vessel , simply activate the individual shape memory elements which will then cause the reorientation of the distal end of the catheter .

[0015] Within the present context , a shape memory element is defined as a component that comprises a shape memory material . A shape memory material is a material that has been deformed, typically during manufacture , and can return to its previous shape due to an activation, for example by heating but also due to exposure to light or electricity or other kinds of stimuli .

[0016] In embodiments , the shape memory elements are arranged at di f ferent circumferential positions along the catheter . By doing so , it becomes possible to tilt the catheter into di f ferent circumferential directions since one can selectively activate the shape memory elements arranged at di f ferent circumferential positions to make the distal end point in di f ferent directions .

[0017] Further optionally, the shape memory elements are arranged at di f ferent longitudinal positions along the catheter . This allows for having di f ferent longitudinal shapes of the catheter that can be activated as desired and in particular for tilting di f ferent longitudinal parts of the catheter point in di f ferent directions since one can selectively activate shape memory elements arranged at di f ferent longitudinal positions to cause di f ferent shapes of the distal end of the catheter .

[0018] In embodiments , the shape memory elements are heat activated . By this , it is meant that they transition to cause the reorientation of the distal end of the catheter when heated above a preset threshold temperature . This allows for an easy to implement way of selectively activating the shape memory elements .

[0019] In embodiments , the shape memory elements have di f ferent activation temperatures . In that way, it becomes possible to cause a phase transition of only one of the shape memory elements by heating the distal end which may comprise potentially more than one shape memory element above a preset threshold temperature that is particular to that shape memory element . In that way, only one of the shape memory elements will be activated whilst the other shape memory elements will not be activated . This makes the endovascular catheter easier to control .

[0020] In embodiments , the tissue ablation means is arranged directly adj acent to the at least one shape memory element so that activation of the at least one shape memory element directly reorients the tissue ablation means . By directly adj acent , it is meant that there are no intervening elements between the at least one shape memory element and the tissue ablation means .

[0021] In that way, it becomes possible for the shape memory element to directly act upon the tissue ablation means which means that that part of the endovascular catheter that carries out the tissue ablation can have its orientation rearranged .

[0022] In embodiments , the shape memory elements comprise a multiple state shape memory material having at least a first and a second activated state . In embodiments , the first and second activated states correspond to di f ferent geometric configurations of the shape memory element . By this feature , it becomes possible to achieve di f ferent configurations using a single shape memory element , namely that shape memory element that comprises a multiple state shape memory material . This simpli fies the structure of the endovascular catheter . In embodiments , such a multiple-state shape memory material comprise shape memory polymers such as polytetrafluoroethylene ( PTFE ) , polylactide ( PLA) , and ethylene-vinyl acetate (EVA) and etc . and / or shape memory alloys such as copper-aluminium- nickel, nickel-titanium (NiTi) , .... Some multi state materials / components are described in Pritha Ghosh et al., "Design of multi-state and smart-bias components using Shape Memory Alloy and Shape Memory Polymer composites", Materials & Design, vol. 44, pp . 164-171.

[0023] In embodiments, the first and second activated states correspond to different shapes of the shape memory element. Accordingly, with the same shape memory element, two different spatial configurations of the distal end can be achieved. This simplifies the structure of the endovascular catheter whilst achieving a highly flexible functionality.

[0024] In embodiments, the at least one shape memory element comprises a shape memory metal. Such shape memory metals are widely used in endovascular catheters and are known for their biocompatibility. Examples of such shape memory metals are nitinol or NiTiCu, which change their shape when brought to a temperature within a range of between -20°C and 70°C. Shape memory metal are more resilient and harder than other shape memory materials, in particular shape memory polymers, so that they are better at keeping their transitioned shape, and have a reasonably short timescale (typically less than 2s) within which they change their shape.

[0025] In alternative embodiments, the at least one shape memory element comprises a shape memory polymer. Shape memory polymers include polytetrafluoroethylene (PTFE) , polylactic acid (PLA) , and ethylenevinyl acetate (EVA) . Shape memory polymers (SMPs) can be activated by heat, electric and light stimuli, so that they are more versatile in their mode of activation. They are generally softer than shape memory alloys, which, in embodiments, makes it easier to advance them to the target site through a patient's vasculature. Among SMPs, there are materials that allow for one way, that is, irreversible, shape changes whilst others undergo reversible shape changes. Some SMPs are also multi-state shape memory materials, that is, depending on their activation, they can assume different activated states. All of these different types of SMPs can be employed in catheters according to the present disclosure . Whilst SMPs generally have slower response times than shape memory alloys , their response times are still fast enough to allow for use in thrombectomy / atherectomy catheters (with some SMPs having response times of about 20 s ) .

[0026] In further embodiments , the shape memory elements are heat activated and have , in embodiments , a transition temperature within the range of from 39 ° C to 45 ° C . Heat activated shape memory elements can be comparatively easily activated in surgical environments which makes them user- friendly and easy to implement . A transition temperature within the range of from 39 ° C to 45 ° C ensures that the temperatures to which the shape memory elements are heated to activate them are not likely to cause harm to a patient .

[0027] In embodiments , the endovascular catheter comprises a means for selectively heating up the shape memory elements . This allows for activating them in situ during surgery .

[0028] In further embodiments , the shape memory elements are electrically activated . This also allows for an easy activation of them by means of conducting electricity to them .

[0029] In further embodiments , the endovascular catheter comprises a means for conducting electricity to the shape memory elements which makes it easy to activate them . Such means for connecting electricity could, in embodiments , take the form of embedded wires or other types of electrical conductors .

[0030] In embodiments , the shape memory elements are light activated and / or chemically activated .

[0031] In yet further embodiments , a thrombectomy or atherectomy system having the endovascular catheter as described before is an aspect of the present disclosure .

[0032] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 schematically depicts a catheter for use in an atherectomy device according to the present invention .

[0033] Figure 2 shows an atherectomy system according to the first embodiment .

[0034] Figure 3 shows the functionality of an endovascular catheter according to the first embodiment .

[0035] Figure 4 schematically depicts the functionality of a catheter according to the first embodiment of the invention .

[0036] DETAILED DESCRIPTION

[0037] Figure 1 shows an endovascular catheter 1 according to an embodiment of the invention . The catheter 1 extends in the longitudinal direction L . The distal end lb of the catheter 1 points in the distal direction . The catheter 1 comprises a stationary part / stator 3 and a rotatable part / rotor 4 at its distal end lb . The rotatable part 4 is at the catheter' s distal end lb and may form the catheter' s distal tip . The rotatable part 4 has a cyl indrical section extending substantially in the longitudinal direction L . Likewise , stationary part 3 has a cylindrical section substantially extending in the longitudinal direction L . The catheter 1 further includes a catheter body 1c arranged proximal to the proximal end of the stationary part 3 . The catheter body 1c extends towards the proximal end of the catheter 1 .

[0038] As can be seen from Figure 1 , the catheter 1 comprises a guidewire 9 which passes through an opening at the distal end lb of the catheter 1 formed inside the distal tip of the rotatable part 4 . The rotatable part 4 and the stationary part 3 are furthermore provided with windows 6 , 7 arranged in an overlapping orientation so that an opening through the rotatable part 4 and the stationary part 3 is formed . Through this opening, a helix 5 is visible . The helix 5 is connected to the rotatable part 4 , in particular at the distal end lb of the rotatable part 4 . The helix 5 transports material removed from the vasculature from the distal end lb of the catheter 1 towards the proximal end of the catheter 1 . Rotation of the helix 5 imparts a rotation to the rotatable part 4 .

[0039] Figure 2 shows an aspiration system 2 , which is an example of an atherectomy / thrombectomy system . The aspiration system 2 comprises in addition to the catheter 1 a handle 10 including a housing 11 and a motor 12 . The motor 12 serves for rotating the helix 5 and hence of the rotatable part 4 . The aspiration system 2 further comprises a control unit 13 for controlling rotation of the rotatable helix 5 and an optional foot switch 14 for controlling the control unit 13 . The aspiration system 2 also comprises a collection bag 15 for collecting material removed from the vasculature .

[0040] Figure 3 shows how the distal end lb of the catheter 1 changes its orientation inside a blood vessel V . As can be seen from Figure 3a ) , the catheter 1 is advanced with its distal tip lb adj acent to thrombotic tissue 0 inside a blood vessel V . In order to get there , it is guided by a guidewire 9 . When it has arrived at that destination, the guidewire 9 can, depending on the details of the implementation, be withdrawn or be left in place and the shape memory element (not illustrated in Figure 3 ) is activated to create a kink K, as shown in Figure 3b ) . As can be seen from Figure 3b ) , the distal end lb of the catheter 1 is thus pointing towards the thrombotic tissue 0 and can thus remove that tissue .

[0041] In order to make the distal end lb of the catheter 1 also point to the other parts of the thrombotic tissue 0 to thereby ablate it , the system as illustrated in Fig . 4 is employed .

[0042] Here , Figure 4d) shows the distal end lb of a catheter 1 . As can be seen from that figure , the catheter 1 has arranged therein three shape memory elements 21 arranged at di f ferent circumferential positions which form a reorientation means . By means of a selective activation of either one of those shape memory elements 21 , the distal end lb of the catheter 1 can be tilted in di f ferent directions to thereby reach thrombotic tissue at di f ferent circumferential positions of a blood vessel . This selective activation can be achieved by means of using di f ferent electrical signal s to activate di f ferent shape memory elements 21 .

[0043] In contrast with this , Figures 4b and 4c show an endovascular catheter in which only a single shape memory element 21 is arranged . As can be seen from comparing Figures 4b and 4c, by means of applying a stimulus to the shape memory elements 21 , the distal end lb of the catheter can be tilted . It can, however, only be tilted in one way so that with a thus designed catheter, a surgeon would need to rotate the catheter 1 to thereby remove thrombotic tissue at di f ferent circumferential positions of the blood vessel .

[0044] Figure 4a shows the change in shape of individual shape memory elements 21 . As can be seen from that figure , the shape memory element 21 arranged on left-hand side is straight prior to activation . However, when being activated, it assumes the shape indicated on the right-hand side which has a kink . This kink is preset into the shape memory element 21 during manufacture .

[0045] REFERENCE S IGNS

[0046] 1 catheter lb distal end of catheter

[0047] 1c catheter tube

[0048] 2 aspiration system

[0049] 3 stationary part ( stator )

[0050] 4 rotatable part ( rotor )

[0051] 5 helix

[0052] 6 window in stationary part

[0053] 7 window in Irotatable part

[0054] 9 guidewire

[0055] 10 handle

[0056] 11 housing

[0057] 12 motor 13 control unit

[0058] 14 foot switch

[0059] 15 collection bag

[0060] 0 occlusion

[0061] V blood vessel

[0062] K kink

[0063] 20 reorientation means

[0064] 21 shape memory element

Claims

CLAIMS1. Endovascular catheter (1) for use in atherectomy or thrombectomy, comprising: a catheter body (1c) having a proximal and a distal end (lb) , the catheter body (1c) extending in a longitudinal direction (L) of the catheter (1) , and a tissue ablation means (4) positioned at the distal end (lb) of the catheter, the tissue ablation means (4) being arranged for ablating thrombotic tissue adhering to the inside of a vessel wall, the catheter body (1c) comprising a reorientation means (20) comprising at least one shape memory element (21) for reorienting the distal end of the catheter, the reorientation means (20) being arranged so that, upon selective activation of the shape memory element (21) , the distal end (lb) of the catheter can be reoriented in at least two different directions .

2. Endovascular catheter (1) according to claim 1, wherein the reorientation means (20) comprises at least two, optionally at least four shape memory elements (21) arranged at different locations along the catheter body that can be individually activated to reorient the distal end (lb) of the catheter ( 1 ) .

3. Endovascular catheter (1) according to claim 2, wherein the shape memory elements (21) are arranged at different circumferential positions along the catheter (1) .

4. Endovascular catheter (1) according to claim 2 or 3, wherein the shape memory elements (21) are arranged at different longitudinal positions along the catheter.

5. Endovascular catheter (1) according to one of claims 2 to 4, wherein the shape memory elements (21) are heat activated.

6. Endovascular catheter (1) according to claim 5, wherein the shape memory elements (21) have different activation temperatures . . Endovascular catheter (1) according to one of the preceding claims, wherein the tissue ablation means (4) is arranged directly adjacent to the at least one shape memory element (21) so that activation of the at least one shape memory element (21) reorients the tissue ablation means (4) .

8. Endovascular catheter (1) according to one of the preceding claims, wherein the shape memory element (21) comprises a multiple-state shape memory material having at least a first and a second activated state.

9. Endovascular catheter (1) according to claim 8, wherein the first and second activated states correspond to different shapes of the shape memory element (21) .

10. Endovascular catheter (1) according to one of the preceding claims, wherein the at least one shape memory element (21) comprises a shape memory metal.

11. Endovascular catheter (1) according to one of the preceding claims, wherein the at least one shape memory element (21) comprises a shape memory polymer.

12. Endovascular catheter (1) according to one of the preceding claims, wherein the shape memory elements (21) are heat-activated, wherein optionally, the transition temperatures are within the range of from 39°C to 45°C.

13. Endovascular catheter (1) according to claim 12, further comprising a means for selectively heating up the shape memory elements (21) .

14. Endovascular catheter (1) according to one of claims 1 to 11, wherein the shape memory elements (21) are electrically activated .

15. Endovascular catheter (1) according to claim 14, further comprising a means for conducting electricity to the shape memory elements (21) .

16. Endovascular catheter (1) according to one of claims 1 to 11, wherein the shape memory elements (21) are light activated and / or chemically activated.

17. Thrombectomy or atherectomy system (2) having the endovascular catheter (1) of one of the preceding claims.

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