Patent Description:
Arterial and venous thromboembolic disease remains a major cause of death and disability. Strokes may be caused by a rupture or bleeding of a cerebral artery ("hemorrhagic stroke"), or a blockage in a cerebral artery due to a thromboembolism ("ischemic stroke"). Intracerebral hemorrhage (ICH) bleeding has long been associated with high rates of morbidity and mortality. Treatment choices for ICH are limited, and the effectiveness of currently available therapies is inadequate. Thrombolytics alone are not recommended, but are currently being investigated for use in conjunction with aspiration and other surgical techniques.

While intracranial hemorrhage is caused by blood clots located outside the blood vessels in the brain, Acute Ischemic Stroke (AIS) is caused by blood clots blocking a blood vessel in the brain arteries. Endovascular and outside of endovascular thromboembolic disease remain very widespread causes of death and disability with no ideally effective treatment currently available. Thus, there is a significant need for improved devices, methods and systems for treating thromboembolic disease.

There are many approaches for removing thromboembolic material from the body, either surgical or using catheter devices for endovascular and outside endovascular removal of obstructive matter, such as blood clots, thrombus, atheroma, plaque and the like. These techniques are related to rotating baskets or impellers, cutters, high pressure fluid injections, Archimedes screw, vacuum, rotating wires and other means.

<CIT> relates to endovascular thrombectomy devices for the endovascular procedures within the neurovascular space. A thrombectomy catheter includes a distal tip having a tip inner diameter (ID); a tip outer diameter (OD); a tip distal end; a tip proximal end; a flared end towards the tip distal end having a flared end ID and a flared end OD; and a variable diameter portion towards the tip proximal end having a variable outer diameter (OD). The thrombectomy catheter may additionally include a proximal shaft having a shaft inner diameter (ID); a shaft outer diameter (OD); a shaft proximal end; and a shaft distal end.

<CIT> a catheter comprising an inner liner, an outer jacket, and a structural support member positioned between at least a portion of the inner liner and the outer jacket. The inner liner, the outer jacket, and the structural support member define a catheter body that comprises a proximal portion having a first outer diameter, a distal portion having a second outer diameter less than the first outer diameter, the distal portion including a distal end of the catheter body, and a medial portion positioned between the proximal portion and the distal portion, the medial portion tapering from the first outer diameter to the second outer diameter.

<CIT> relates to a special catheter for thrombus aspiration from a distal cerebral vessel, the catheter comprising a catheter base, a stress release tube, and a tube body. The main body part of the tube body is composed of three layers including an inner layer, a woven layer and an outer layer, wherein the material of the outer layer is mainly prepared from one of more of nylon, PEBAX and TPU polyester materials mixed with one another. The material of the outer layer uses a sectional design, and is designed according to the physiological anatomical structure of the cerebral vessel to provide the corresponding flexibility according to different sections of a blood vessel, such that the catheter can effectively adapt to the structure of a blood vessel to facilitate the catheter in reaching a lesion position.

<CIT> relates to novel enhanced ischemic stroke thrombus aspiration systems, processes, and products. More specifically, it is directed to a large bore aspiration catheter configured for the removal and/or destruction of an occlusion within a vessel, particularly for the removal of thrombus material from within a cerebral artery so as to restore blood flow therethrough and minimize damage to affected brain tissue.

Removal of thromboembolic material and blood clots from brain arteries are described using several devices and methods such as: embolectomy devices, clot pullers, retrieving devices or separating devices with aspiration. While most of these devices are capable of removing blood clots from the human arteries, there is still a clinical need for a simple, quick and easy access with devices to the treatment site through tortuous brain arteries, and safe removal of blood clots in a single pass. Often, catheters used to remove clots from brain arteries get clogged after partial removal of clots even under absolute vacuum. Thus, there is a need for more efficient and effective devices that facilitate a quick and single pass for the removal of thromboembolic material. In particular, the inventors of the present disclosure found that an aspiration catheter allowing a sufficient aspiration force may alleviate the problems with existing removal systems.

Therefore, there is still a need to provide an aspiration catheter and clot removal system which improves therapeutic results and which can be fabricated economically, at the same time being robust even in challenging application environments.

Advantageous embodiments of the present invention are the subject matter of the dependent claims.

The present invention is based on the idea that a sufficiently high removal force and efficiency may be achieved by combining a large inner open lumen diameter of the catheter with a low outer diameter and a sufficiently large catheter inner volume. In particular, the present disclosure provides an aspiration catheter for a clot removal system, the catheter having a distal section and a proximal section, wherein, in the distal section, a ratio of an outer diameter and an open lumen inner diameter is in a range between <NUM> and <NUM>, the lumen inner diameter is in a range between <NUM> *<NUM>-<NUM>m (<NUM> inch) and <NUM> *<NUM>-<NUM>m (<NUM> inch), and wherein a volume of the catheter is in a range between <NUM> *<NUM>-<NUM>m<NUM> (<NUM> cubic inch) and <NUM><NUM> (<NUM> cubic inch). The length of the catheter is in a range between <NUM> (<NUM>) and <NUM> (<NUM>), It could be shown that with such an aspiration catheter an enhanced thrombus removal force and an enlarged thrombus entry area may be achieved. At the same time, the outer diameter is small enough to allow navigation into narrow passages.

As used herein, the terms "proximal" and "distal" are to be taken as relative to a user using the disclosed aspiration devices. "Proximal" is to be understood as relatively closer to the user and "distal" is to be understood as relatively farther away from the user. Further, as this is generally known, the outer diameters of a catheter are given in F ("French"), <NUM> F being <NUM>,<NUM> inches (<NUM>).

According to an advantageous example, in the distal section, the open lumen inner diameter is <NUM> *<NUM>-<NUM>m (<NUM> inches) and the outer diameter is <NUM> *<NUM>-<NUM>m (<NUM> F), and wherein the total volume of the catheter is <NUM> *<NUM>-<NUM>m<NUM> (<NUM> cubic inches), the catheter having a length of <NUM>.

The present invention is further based on the idea that particularly advantageous characteristics of the aspiration catheter may be obtained by providing, in addition to the proximal and distal sections, one or more intermediate sections with different cross sectional geometries and characteristics compared to the proximal and distal sections. For example, the aspiration catheter may further comprise at least one intermediate section, wherein the distal section, the at least one intermediate section, and the proximal section are arranged adjacently, and wherein each section has an increasing wall thickness with the proximal section having the highest wall thickness. However, the thickness may also vary differently, i. being smaller at certain sections. Moreover, the one or more intermediate section may also differ from the distal and proximal section by physical and/or chemical characteristics, such as hardness, material composition and/or structure. For instance, the one or more intermediate sections may comprise different reinforcement layers, which differ in material and/or structure from the reinforcement layer of the adjacent sections. As reinforcement layers, coils or braids or slotted tubes made from various metals, e. Nitinol, a metal alloy of nickel and titanium which has a shape memory, tungsten, or stainless steel, or a combination of these materials may be used.

According to a further advantageous example, the distal section comprises an inner liner, a reinforcement layer encompassing the inner liner, and an outer jacket encompassing the reinforcement layer, wherein a total thickness of inner liner, the reinforcement layer, and the outer jacket is in a range between <NUM> *<NUM>-<NUM>m (<NUM> inches) and <NUM> *<NUM>-<NUM>m (<NUM> inches). Such comparatively small wall thicknesses allow for a large open lumen inner diameter in combination with a low outer diameter, so that the aspiration catheter can be introduced into small vessels. For stabilizing such thin walls, the reinforcement layer may for instance be formed from a Nitinol coil having a comparatively high wraps per inch (WPI) count. For instance, a WPI count between <NUM> and <NUM> (a wraps per meter count between <NUM> and <NUM>) may be chosen.

In order to provide the open lumen throughout the catheter with a smooth and inert inner surface the inner liner may comprise a PTFE layer extending along all sections of the catheter.

As mentioned above, the reinforcement layer may comprise Nitinol, tungsten, or stainless steel, or a combination of these materials. Nitinol has the advantage of showing a shape memory effect, which is advantageous for controlling the maneuvering of the distal section of the catheter. In particular, the reinforcement layer in the distal section may comprise a coil, the coil being formed from a wire with a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) and a tightness of <NUM> to <NUM> wraps per inch (<NUM> to <NUM> wraps per meter).

According to the present disclosure, any suitable material may be chosen for the outer jacket in any of the sections. However, the inventors found that particularly advantageous characteristics may be achieved if the outer jacket comprises a layer of a polyamide material, e. polyether block amide (for instance PEBAX® or VESTAMIDO) and/or if the outer jacket comprises a layer of an aliphatic polyether-based thermoplastic elastomer.

Furthermore, according to an advantageous example of the present disclosure, each of the distal section, the at least on intermediate section, and the proximal section have outer jackets with different thickness and/or hardness. For instance, a Shore hardness may vary between 35D and 72D. As this is known in the art, there are different Shore hardness scales for measuring the hardness of different materials and there is overlap on the different scales. For example, a material with a Shore hardness of 95A is also a Shore 45D. The Shore D hardness scale measures the hardness of hard rubbers, semi-rigid plastics and hard plastics.

According to a further advantageous example, the reinforcement layer in at least one of the at least one intermediate section and the proximal section comprises a braid with a pic count in a range between <NUM> PPI and <NUM> PPI (<NUM> pics per meter and <NUM> pics per meter).

Furthermore, the reinforcement layer in at least one of the at least one intermediate section and the proximal section may comprise a coil with a coiling in a range between <NUM> WPI (<NUM> wraps per meter) and <NUM> WPI (<NUM> wraps per meter).

In order to reach the desired inner volume of the aspiration catheter according to the present disclosure, the aspiration catheter is comparatively long, it may for instance have a total length of <NUM>.

The present disclosure further provides a clot removal system (also referred to as a thromboembolic system) comprising an extraction device with an aspiration catheter according to the present disclosure and drive unit with a vacuum pump device. The clot removal system can be provided as a single unit with affixed components, or the components of the system may be detachable and attachable before, during or after the thromboembolic material removal procedure.

The devices and systems of the present disclosure relate to removal of thromboembolic material that include but are not limited to: clots, thrombus, atheroma, fluid, polyps, cysts or other obstructive matter from endovascular system. The endovascular system includes arteries, veins, previously implanted stents, grafts, shunts, fistulas and the like. Removal of thromboembolic materials may also include locations outside of the endovascular system such as: body organs, head, ureters, bile ducts, fallopian tubes, localized tumors, cancerous tissue removal or other particular target site. In the following, the term "clot removal system" is intended to cover all these applications.

The accompanying drawings are incorporated into the specification and form a part of the specification to illustrate several embodiments of the present invention. These drawings, together with the description serve to explain the principles of the invention. The drawings are merely for the purpose of illustrating the preferred and alternative examples of how the invention can be made and used, and are not to be construed as limiting the invention to only the illustrated and described embodiments. Furthermore, several aspects of the embodiments may form-individually or in different combinations-solutions according to the present invention. The following described embodiments thus can be considered either alone or in an arbitrary combination thereof. The described embodiments are merely possible configurations and it must be borne in mind that the individual features as described above can be provided independently of one another or can be omitted altogether while implementing this invention. Further features and advantages will become apparent from the following more particular description of the various embodiments of the invention, as illustrated in the accompanying drawings, in which like references refer to like elements, and wherein:.

In the following, the present invention will be described in detail with reference to the Figures, first referring to <FIG> shows a schematic side view of an aspiration catheter <NUM> according to a first example, <FIG> shows a schematic cross sectional view of a distal section <NUM> of the catheter <NUM>. It is important to note that in all the Figures the shown dimensions are highly schematic and may by no means be interpreted as being true to scale. In particular, the longitudinal dimensions of the catheter are represented strongly shortened, whereas the layers of the cross section are exaggerated in their thickness.

As may be seen from <FIG>, the aspiration catheter <NUM> comprises four different sections: Firstly the distal section <NUM>, adjacent thereto a first intermediate section <NUM> and a second intermediate section <NUM>. The proximal section <NUM> is arranged at the end of the aspiration catheter <NUM> which is connected to a drive device.

As can be seen from <FIG>, the distal section <NUM> of the catheter <NUM> comprises three layers. The innermost layer is a liner <NUM> which may pass through the complete length of the catheter <NUM>. For reinforcing the catheter <NUM>, a reinforcement layer <NUM> is provided. An outer jacket <NUM> is arranged as the outermost layer encompassing the other layers. The inner diameter ID may for instance be as large as <NUM> *<NUM>-<NUM>m (<NUM> inches).

According to the present disclosure, a distal outer diameter Dd of <NUM> *<NUM>-<NUM>m (<NUM> F) can be achieved. This is possible by providing a comparatively low total thickness of the various layers, for instance by forming the reinforcement layer <NUM> as a Nitinol wire coil, the wire having a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) and a WPI count of <NUM> (<NUM> wraps per meter). The outer jacket <NUM> in the distal section <NUM> is for instance formed by a PEBAX® layer with a shore hardness of 35D and a thickness of <NUM> *<NUM>-<NUM>m (<NUM> inches). The inner liner <NUM> is advantageously formed by a combination of an inner PTFE layer (e. <NUM> *<NUM>-<NUM>m (<NUM> inches)) and a thinner outer layer of an aliphatic polyether-based thermoplastic elastomer such as Tecoflex® (<NUM> *<NUM>-<NUM>m (<NUM> inches)). In the shown example, the distal section has a length of <NUM> (<NUM>). The total length of the aspiration catheter <NUM> is chosen to be <NUM> (<NUM>), so that a total inner volume of <NUM> *<NUM>-<NUM>m<NUM> (<NUM> cubic inches) is obtained. According to the present disclosure, each of the sections <NUM>, <NUM>, <NUM>, <NUM> has a different outer jacket and/or reinforcement layer, but the identical liner is running along the complete length of the aspiration catheter <NUM>.

For instance, the first intermediate section <NUM> is formed using a 55D shore hardness PEBAX® outer jacket having a thickness of <NUM> *<NUM>-<NUM>m (<NUM> inches). According to the claimed invention, the first intermediate section <NUM> is subdivided into two sub-sections wherein the first sub-section is reinforced by another Nitinol wire coil (diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) and a WPI count of <NUM> (<NUM> wraps per meter)) and the second sub-section is reinforced by a stainless steel wire coil, the wire having a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) and a WPI count of <NUM> (<NUM> wraps per meter). The first intermediate section <NUM> may have a length of <NUM> (<NUM>), each of the subsections having a length of <NUM> (<NUM>).

Furthermore, adjacent to the first intermediate section <NUM>, a second intermediate section <NUM> is arranged which has an outer jacket formed from a 63D PBAX® with a thickness of <NUM> *<NUM>-<NUM>m (<NUM> inches). The reinforcement layer of the second intermediate section <NUM> is for instance formed by a stainless steel wire coil having a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) and a WPI count of <NUM> (<NUM> wraps per meter) the second intermediate section <NUM> may have a length of <NUM> (<NUM>).

Finally, adjacent to the second intermediate section <NUM>, the proximal section <NUM> is arranged, which may be brought into contact with the drive device. The proximal section <NUM> is the longest section (<NUM> (<NUM>)) and comprises a 72D PBAXO outer jacket with a thickness of <NUM> *<NUM>-<NUM>m (<NUM> inches). The reinforcement layer in the proximal section <NUM> is advantageously of the same type as in the second intermediate section <NUM>, namely a stainless steel wire coil having a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) and a WPI count of <NUM> (<NUM> wraps per meter). The proximal section <NUM> does not have to have such an extremely small outer diameter Dp. In the present example, the outer diameter of the proximal section <NUM> has for instance <NUM> *<NUM>-<NUM>m (<NUM> F).

With the above explained particular combination of materials, a sufficiently stable and steerable structure can be provided, at the same time achieving a particularly large inner diameter ID in combination with a small outer diameter Dd.

Turning now to <FIG>, a further example of an aspiration catheter <NUM> will be explained in the following. The aspiration catheter <NUM> differs from the catheter <NUM> according to the first example in that a much greater variety of intermediate sections 204A to 204F is provided. Furthermore, not only wire coils are used for the reinforcement layers, but also wire braids. In particular, a coil zone <NUM> is provided within about <NUM> (<NUM>) from the distal tip and a braid zone <NUM> is provided for the rest of the aspiration catheter <NUM>. The coils in the coil zone <NUM> are formed from a Nitinol wire having a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) and varying wrap counts (WPI) as shown in <FIG>.

In the braid zone <NUM>, a stainless steel braiding is provided as the reinforcement layer with a DL load pattern of <NUM> *<NUM>-<NUM>m (<NUM> inches) times <NUM> *<NUM>-<NUM>m (<NUM> inches). The varying PPI counts are given in <FIG>.

In the present example, the outer diameter Dd of the distal section <NUM> is <NUM> *<NUM>-<NUM>m (<NUM> F) and the outer diameter Dp of the proximal section <NUM> has for instance a value of <NUM> *<NUM>-<NUM>m (<NUM> F). The total length of the aspiration catheter <NUM> is <NUM> (<NUM>). The inner diameter ID is <NUM>,<NUM> *<NUM>-<NUM>m (<NUM> inch), so that a total inner volume of <NUM> *<NUM>-<NUM>m<NUM> (<NUM> cubic inches) is obtained.

The following table <NUM> summarizes the material characteristics for the aspiration catheter <NUM> of the second example.

In combination with the above materials for the outer jacket <NUM>, a liner <NUM> is provided which comprises an inner layer of <NUM> *<NUM>-<NUM>m (<NUM> inches) PTFE and an outer layer of <NUM> *<NUM>-<NUM>m (<NUM> inches) Tecoflex®. Of course, any other liner material and material combination may also be used.

Advantageously, the aspiration catheter <NUM> has a further improved performance regarding distal flexibility, trackability, aspiration volume, and proximal stiffness.

Turning now to <FIG>, a further example of an aspiration catheter <NUM> will be explained in the following. The aspiration catheter <NUM> differs from the catheter <NUM> according to the first example in that a much greater variety of intermediate sections 304A to 304F is provided. Furthermore, not only wire coils are used for the reinforcement layers, but also a braiding. In particular, a coil zone <NUM> is provided within about <NUM> (<NUM>) from the distal tip and a braid zone <NUM> is provided for the rest of the aspiration catheter <NUM>. The coils in the coil zone <NUM> are formed from a Nitinol wire having a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches) or a tungsten wire having a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches), the wire being applied with varying wrap counts (WPI) as shown in <FIG>.

In the braid zone <NUM>, a stainless steel braiding is provided as the reinforcement layer with a flat wire having a rectangular cross section of <NUM> *<NUM>-<NUM>m (<NUM> inches) times <NUM> *<NUM>-<NUM>m (<NUM> inches). The varying pics per inch (PPI) counts are given in <FIG>. The third example differs from the second example by the particular values of the WPI and PPI counts.

In the example of <FIG>, the outer diameter Dd of the distal section <NUM> is <NUM> *<NUM>-<NUM>m (<NUM> F) and the outer diameter Dp of the proximal section <NUM> has for instance a value of <NUM> *<NUM>-<NUM>m (<NUM> F). The total length of the aspiration catheter <NUM> is <NUM> (<NUM>). The inner diameter ID is <NUM> (<NUM> inch), so that a total inner volume of <NUM> *<NUM>-<NUM>m<NUM> (<NUM> cubic inches) is obtained.

The following table <NUM> summarizes the material characteristics for the aspiration catheter <NUM> of the third example.

Advantageously, the aspiration catheter <NUM> has a further improved performance regarding distal flexibility, trackability, and proximal stiffness. A highest thrombus removal force of <NUM> N (<NUM> gf) can be generated at a -<NUM> *<NUM>-<NUM>m (-<NUM> inch) Hg vacuum.

<FIG> illustrate a perspective view of an aspiration catheter <NUM> according to the first example, having a distal tip <NUM> and a proximal tip <NUM>. The proximal tip <NUM> is formed to be connected to a drive unit comprising a vacuum pump. It should be noted that the aspiration catheters <NUM>, <NUM> according to the second and third example will essentially look the same as the aspiration catheter <NUM> according to the first example.

As can be seen from <FIG>, the longitudinal dimension of the catheter having for instance a length of <NUM> (<NUM>) is comparatively large, while the outer diameter at the distal tip <NUM> is very small.

In summary, the present disclosure provides a particularly advantageous ratio of the outer diameter Dd in the distal section and the open lumen inner diameter ID, i. particularly close to the value <NUM>. For instance, an inner diameter ID as large as <NUM> *<NUM>-<NUM>m (<NUM> inches) could be reached for a <NUM> *<NUM>-<NUM>m (<NUM> F) outer diameter. The inner layer, the reinforcement layer and the outer layers are accommodated within a thickness of <NUM> *<NUM>-<NUM>m (<NUM> inches). According to the present disclosure, three different types of reinforcement may be used, namely Nitinol round wire with a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches), stainless steel 304V round wire with a diameter of <NUM> *<NUM>-<NUM>m (<NUM> inches), and tungsten flat wire with a rectangular cross section of <NUM> *<NUM>-<NUM>m (<NUM> inches) x <NUM> *<NUM>-<NUM>m (<NUM> inches).

The PPI range of the braid varies from <NUM> PPI (<NUM> pics per meter) to <NUM> PPI (<NUM> pics per meter) and the coiling WPI range varies from <NUM> WPI (<NUM> wraps per meter) to <NUM> WPI (<NUM> wraps per meter). The particular variations along the longitudinal axis of the aspiration catheter gives designed performance output like distal flexibility, trackability, proximal stiffness and aspiration volume.

The outer jacket segment materials used in the particular sections and their specific lengths further contribute to the particular desired performance.

It could be shown that a maximum thrombus removal force of <NUM> N (<NUM> gf) can be generated by a <NUM> *<NUM>-<NUM>m (<NUM> F) outer diameter aspiration catheter at -<NUM> *<NUM>-<NUM>m (-<NUM> inch) Hg vacuum.

Claim 1:
Aspiration catheter for a clot removal system, the aspiration catheter (<NUM>) having a distal section (<NUM>) and a proximal section (<NUM>),
wherein, in the distal section (<NUM>), a ratio of an outer diameter (Dd) and an open lumen inner diameter (ID) is in a range between <NUM> and <NUM>, and
wherein a volume of the aspiration catheter (<NUM>) is in a range between <NUM> *<NUM>-<NUM>m<NUM> (<NUM> cubic inch) and <NUM>*<NUM>-<NUM> m<NUM> (<NUM> cubic inch),
wherein the aspiration catheter (<NUM>) further comprises at least one intermediate section (<NUM>, <NUM>),
wherein the distal section (<NUM>), the at least one intermediate section (<NUM>, <NUM>), and the proximal section (<NUM>) are arranged adjacently,
characterised in that
the at least one intermediate section (<NUM>, <NUM>) comprises a reinforcement layer (<NUM>),
wherein the at least one intermediate section (<NUM>, <NUM> ) comprises two sub-sections,
wherein the reinforcement layer (<NUM>) comprises a coil, the coil being formed from a wire ,
wherein a diameter of the wire at a first sub-section of the at least one intermediate section (<NUM>, <NUM>) is <NUM> *<NUM>-<NUM>m, (<NUM> inches), and has a wraps per meter count of <NUM> (wraps per inch, WPI, of <NUM>), and a diameter of the wire at a second sub-section of the at least one intermediate section (<NUM>, <NUM>) is <NUM> *<NUM>-<NUM>m, (<NUM> inches), and has wraps per meter count of <NUM> (wraps per inch of <NUM>), and
wherein the wire of the coil in the first sub-section comprises Nitinol and the wire of the coil in the second sub-section comprises stainless steel.