CLOT RETRIEVAL DEVICE FOR REMOVING CLOT FROM A BLOOD VESSEL
A clot retrieval device 1 for removing occlusive clot from a blood vessel, the device comprises an inner elongate body 3 having a collapsed delivery configuration and an expanded deployed configuration and an outer elongate body 2 at least partially overlying the inner elongate body 2. The outer elongate body 2 is expandable to a radial extent which is greater than the radial extent of the inner body 3 in the deployed configuration to define a clot reception space 11. The outer elongate body 2 comprises a distal end portion 24,49 and the inner elongate body 3 comprises a main body portion 10 and a distal portion which extends in the deployed configuration towards the outer elongate body 2 to a greater extent than the main body portion. The distal portion 10 of the inner elongate member 3 and the distal end portion 24,49 of the outer elongate body 2 together define a three dimensional protective structure to substantially prevent distal egress of clot or clot fragments from the device.
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This invention relates to devices and methods of removing acute blockages from blood vessels. The invention especially relates to removing acute obstructions from blood vessels. Acute obstructions may include clot, misplaced devices, migrated devices, large emboli and the like. Thromboembolism occurs when part or all of a thrombus breaks away from the blood vessel wall. This clot (now called an embolus) is then carried in the direction of blood flow. An ischemic stroke may result if the clot lodges in the cerebral vasculature. A pulmonary embolism may result if the clot originates in the venous system or in the right side of the heart and lodges in a pulmonary artery or branch thereof. Clots may also develop and block vessels locally without being released in the form of an embolus—this mechanism is common in the formation of coronary blockages. The invention is particularly suited to removing clot from cerebral arteries in patients suffering acute ischemic stroke (AIS), from pulmonary arteries in patients suffering from pulmonary embolism (PE), from coronary native or graft vessels in patients suffering from myocardial infarction (MI), and from other peripheral arterial and venous vessels in which clot is causing an occlusion.
BACKGROUNDThere are significant challenges associated with designing clot removal devices that can deliver high levels of performance:
There are a number of access challenges that make it difficult to deliver devices. In cases where access involves navigating the aortic arch (such as coronary or cerebral blockages) the configuration of the arch in some patients makes it difficult to position a guide catheter. These difficult arch configurations are classified as either type 2 or type 3 aortic arches with type 3 arches presenting the most difficulty. The tortuosity challenge is even more severe in the arteries approaching the brain. For example it is not unusual at the distal end of the internal carotid artery that the device will have to navigate a vessel segment with a 180° bend, a 90° bend and a 360° bend in quick succession over a few centimetres of vessel. In the case of pulmonary embolisms, access may be gained through the venous system and then through the right atrium and ventricle of the heart. The right ventricular outflow tract and pulmonary arteries are delicate vessels that can easily be damaged by inflexible or high profile devices. For these reasons it is desirable that the clot retrieval device be compatible with as low profile and flexible access and support catheters as possible.
The vasculature in the area in which the clot may be lodged is often fragile and delicate. For example neurovascular vessels are more fragile than similarly sized vessels in other parts of the body and are in a soft tissue bed. Excessive tensile forces applied on these vessels could result in perforations and hemorrhage. Pulmonary vessels are larger than those of the cerebral vasculature, but are also delicate in nature, particularly those more distal vessels.
The clot may comprise any of a range of morphologies and consistencies. Long strands of softer clot material may tend to lodge at bifurcations or trifurcations, resulting in multiple vessels being simultaneously occluded over significant lengths. More mature and organized clot material is likely to be less compressible than softer fresher clot, and under the action of blood pressure it may distend the compliant vessel in which it is lodged. Furthermore the inventors have discovered that the properties of the clot may be significantly changed by the action of the devices interacting with it. In particular compression of blood clot causes dehydration of the clot and results in a dramatic increase in both clot stiffness and coefficient of friction.
The clots may not only range in shape and consistency, but also may vary greatly in length, even in any one given area of the anatomy. For example clots occluding the middle cerebral artery of an ischemic stroke patient may range from just a few millimeters to several centimeters in length.
Stent-like clot retrievers are being increasingly used to remove clot from cerebral vessels of acute stroke patients. These are self expanding devices, similar in appearance to a stent attached to the end of a long shaft, and are advanced through a microcatheter and deployed across clot obstructions in order to trap and retrieve them. They rely on a pinning mechanism to grab the clot by trapping the clot between the self-expanding stent-like body and the vessel wall. This approach has a number of disadvantages:
A stent-like clot retriever relies on its outward radial force (RF) to retain its grip on the clot. If the RF is too low the stent-like clot retriever will lose its grip on the clot, but if the RF is too high the stent-like clot retriever may damage the vessel wall and may require too much force to withdraw. Therefore stent-like clot retrievers that have sufficient radial force to deal with all clot types may cause vessel trauma and serious patient injury, and stent-like clot retrievers that have appropriate radial force to remain atraumatic may not be able to effectively handle all clot types.
The stent-like clot retriever pinning mechanism tends to compress the trapped clot. This compressive force will tend to dehydrate the clot, which in turn tends to increase its coefficient of friction, making it more difficult to remove from the vessel.
Conventional Stent-like clot retriever designs do not retain their expanded shape very well when placed in tension in bends, due to the manner in which their strut elements are connected to one another. This can result in a loss of grip on a clot as the stent-like clot retriever is withdrawn proximally around a bend in a tortuous vessel, with the potential escape of the captured clot. This occurs because the struts of the stent-like clot retriever are placed in tension when it is retracted. This tension is due to friction between the device and the blood vessel, and is increased if an additional load is applied load such as that provided by a clot. In a bend the struts on the outside of the bend are placed in higher tension than those on the inside. In order to attain the lowest possible energy state the outside surface of the stent moves towards the inside surface of the bend, which reduces the tension in the struts, but also reduces the expanded diameter of the stent-like clot retriever.
Another disadvantage with this approach is that it relies on pinning the clot between the stent-like clot retriever and the vessel wall and thus may not restrain the clot effectively when passing a branch vessel or when passing into a vessel that is larger than the fully expanded diameter of the stent-like clot retriever.
Pinning the clot between the stent-like clot retriever and the vessel wall in order to remove it from the vessel also results in high shear forces against the side of the clot as it is removed, potentially releasing fragments of the clot. If these fragments are not retained by the device they may be released leading to further blockages in the distal vasculature.
A particular difficulty encountered when attempting to remove long clots is that conventional devices may be shorter than the clot itself. A device that is shorter than the clot is unlikely to be able to restore flow through the occluded area upon deployment, and thus the pressure gradient across the clot remains a significant impediment to its removal. Simply making such a device longer would likely render it difficult to track through tortuous anatomies and could be traumatic to the vasculature, taking more force to withdraw and potentially getting stuck and requiring surgery to remove.
For many reasons including some or all of the above limitations it is often necessary for a physician to make multiple passes with a clot retrieval device in order to fully remove an obstructive clot. However each time a clot retrieval device is withdrawn the access to the target site is lost. Thus it is necessary to re-advance a guidewire and microcatheter to access and re-cross the clot, and then remove the guidewire and advance the clot retrieval device through the microcatheter. Navigating the guidewire and microcatheter to the clot can take a considerable amount of time especially if the vessels are tortuous. This additional time and device manipulation all adds to the risks to which the patient is exposed.
The challenges described above need to be overcome for any device to provide a high level of success in removing clot, restoring flow and facilitating good patient outcomes. Existing devices do not adequately address these challenges.
STATEMENT OF THE INVENTIONAccording to the invention there is provided a clot retrieval device for removing occlusive clot from a blood vessel, the device comprising:
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- an inner elongate body having a collapsed delivery configuration and an expanded deployed configuration;
- an outer elongate body at least partially overlying the inner elongate body;
- the outer elongate body being expandable to a radial extent which is greater than the radial extent of the inner body in the deployed configuration to define a clot reception space;
- wherein the outer elongate body comprises a distal end portion; and
- wherein the inner elongate body comprises a main body portion and a distal portion which extends in the deployed configuration towards the outer elongate body to a greater extent than the main body portion,
- the distal portion of the inner elongate member and the distal end portion of the outer elongate body together defining a three dimensional protective structure to substantially prevent distal egress of clot or clot fragments from the device.
In this aspect of the invention the embolization risk is reduced by providing a distal net or scaffolding zone across the vessel lumen towards the distal end of the device. This scaffolding in this case is appended to both the inner or outer member or to both members, and is three dimensional in that it has depth as well as surface area. Combining the scaffolding of both inner and outer members provides a more effective filter than utilizing one member alone. In some cases fibres or fine wires are utilised to provide added scaffolding with minimal impact on device profile or deliverability.
In one embodiment the distal portion of the inner elongate body comprises a plurality of struts which are configured in a volumetric pattern.
In one case the distal portion of the inner elongate body comprises a bulged or flared framework of struts.
In one embodiment the distal end portion of the outer elongate body comprises distal struts. In one case the distal struts of the distal end portion of the outer elongate member are configured in a generally conical shape.
In one embodiment at least some of the struts comprise an attachment point, such as an eyelet, for reception of a fibre. The protective structure may include a plurality of fibres providing a distal net.
In one embodiment the outer elongate body comprises a first monolithic structure.
In one embodiment the inner elongate body comprises a second monolithic structure.
In one case wherein the inner elongate body extends proximally of a proximal end of the outer elongate body.
In one embodiment the outer elongate body comprises a plurality of clot receiving openings and a plurality of clot engaging regions, and wherein the clot engaging regions are adapted, on engagement with clot, to urge clot towards the clot receiving openings and into the reception space between the outer elongate body and the inner elongate body.
The clot engaging regions of the outer elongate body comprises scaffolding openings, the clot receiving openings being substantially larger than the scaffolding openings.
In one embodiment the outer elongate body comprises at least two longitudinally spaced-apart segments. There may be at least one hinge is provided between the segments.
The disclosed designs overcome many of the disadvantages of existing mechanical thrombectomy solutions.
Various interchangeable terms are used herein to describe those portions of the invention that are configured to engage with the clot, being generally deployed within the clot and engaging with it. These terms include “clot engaging portion”, “expandable member”, “expandable body”, “clot engaging element”; while the terms “elongate basket”, “engaging basket” and “stent basket” may also be used to describe this portion of the device.
Designs are disclosed in which a clot engaging portion of the device is configured to be expanded within an occlusive clot in a blood vessel so that the expanding engager allows the clot to migrate into a reception space within the body of the engager as the engager expands. The engager is delivered through a catheter to the site of the occlusion and is positioned within the clot. The engager is expandable at the site of the occlusion and starts to compress the clot as it is expanded. The engager surface comprises inlet openings and the inlet openings allow the clot to ‘escape’ from compression by displacing a significant portion of the clot through the inlet openings in the wall of the engager. Because a significant portion of the clot is urged through the inlet openings in the engager this minimizes compression of the clot and hence minimizes the resultant increase in the clot coefficient of friction. This also reduces the radial force on the vessel in the region of the clot which means a lesser force is required to withdraw the captured clot, which in turn means less vessel trauma and less tension on the distal vascular bed. The device is configured such that the radial force of the device acts strongly at a small diameter to engage with and grip clot, but acts softly at a larger diameter to gently contact the vessel wall are also disclosed.
Designs with dual expandable members are disclosed whereby the device comprises a first inner expandable member and a second outer expandable member the inner member being arranged substantially within the lumen of the outer member. The properties of the inner and outer members may be tailored independently of each other. The inner member may have a very different radial force to the outer member. The inner member may have a very different level of porosity to the outer member. The inner member may have a fully expanded diameter that is very different to that of the outer member. The length of the inner member may be different to that of the outer member. The shape of the struts of the inner member may be different to the shape of the struts of the outer member. There may be a clearance between the inner member and the outer member in the expanded configuration. There may be a clearance between the inner member and the outer member in the collapsed configuration. One, or both or neither of the inner and outer members may have a seam which runs substantially longitudinally along at least a portion of the wall of the member. One, or both of the inner and outer members may comprise a laser cut member, a braided member, a knitted member, an extruded member, a pultruded member, One or both of the inner and outer members may be manufactured with a process involving a laser cutting step, a braiding step, a knitting step, an extrusion step, a pultrusion step, an electropolishing step, a heat treatment step. One or both of the inner and outer members may comprise a tapered section, a flared section, a closed end section or a closed mid section. One or both members may comprise a substantially tubular or cylindrical section.
These dual expandable member devices have a number of benefits. (1) The inner member can be configured to provide a strong opening force to create a lumen through the clot and restore flow immediately on deployment. This flow lumen reduces the pressure gradient across the clot, making it easier to remove the clot. (2) The diameter to which the inner member expands may be tailored so as to reduce the risk of a reperfusion injury. With this embodiment the inner member expands to a diameter that is significantly smaller than the diameter of the vessel immediately adjacent to and distal of the occlusion. This small diameter inner member creates a small flow lumen across the occlusion and restricts the initial blood flow to the affected portion of the brain. This restricted blood flow ensures that the pressure applied to blood vessels immediately after flow restoration is lower than normal and this reduces the risk of bleeding in the ischemic vascular bed. Full perfusion is subsequently restored by removing the device and the clot. (3) The inner member may be configured to expand to a lesser diameter than the outer basket and to a lesser diameter than any vessel in which it is to be deployed. This means that a strong radial force may be safely exerted on the clot to open up a flow lumen, but need not be exerted on the vessel. (4) The inner member can serve to scaffold the lumen created through the clot, preventing the liberation of emboli from the clot into the resultant fast flowing bloodstream. (5) The inner member may at least partially comprise a stent and can provide a strong grip on the clot for the critical initial step of disengaging the clot from the vessel, enabling the outer basket to be configured with a low radial force. (6) The outer member may be configured to have large inlet openings so as to urge clot across the wall of the outer. The inner member on the other hand may be configured to prevent distal migration or fragmentation or embolization of clot that traverses the wall of the outer member. By configuring the outer member so as to encourage clot to traverse the wall of the outer member the device can more effectively disengage clot from the wall of the vessel while the device is also effective at preventing loss of clot material with an inner member with a shape and substructure that provides scaffolding.
Designs are also disclosed which further reduce this embolization risk by providing a distal net or scaffolding zone across the vessel lumen towards the distal end of the device. This scaffolding may be appended to either the inner or outer member or to both members, and may be three dimensional in that it has depth as well as surface area. Combining the scaffolding of both inner and outer members may provide a more effective filter than utilizing one member alone. Designs are disclosed utilising fibres or fine wires to provide added scaffolding with minimal impact on device profile or deliverability.
Designs are disclosed of devices with long and highly flexible inner members which may extend significantly proximally of the outer member, enabling the device to be used to retrieve particularly long clots. The small diameter and flexible inner member expands to provide a flow lumen through the clot (reducing the pressure gradient and making the clot easier to remove) but does not expand to the diameter of the vessel in which it is deployed. Thus the resultant device can be delivered and retrieved more safely (at much lower forces) than a similar length device whose diameter was configured to engage with the vessel over its entire length.
Designs are also disclosed of clot retrieval structures from which portions can be detached and left in-situ as implants. This might be desirable as a bail-out option in the event that the device became lodged in place and the physician felt that the force required to retrieve device was too high to be safely applied. This might also be desirable in the event that the occlusion was thrombotic or atherosclerotic—in which case the outer member could be detached and left in place as a stent to maintain a flow lumen through the clot and scaffold the lesion. Detachable designs are disclosed in which the outer member can be detached from the inner member, and in which one or both ends of the outer member can be reconfigured to allow the outer member to expand to a generally tubular shape which can appose the lesion and/or vessel wall.
Various embodiments of the invention are described in more detail below. Within these descriptions various terms for each portion of the devices may be interchangeably used as discussed previously. Each of the described embodiments are followed by a list of further qualifications (preceded by the word “wherein”) to describe even more detailed versions of the preceding headline embodiment. It is intended that any of these qualifications may be combined with any of the headline embodiments, but to maintain clarity and conciseness not all of the possible permutations have been listed.
In one embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and an expandable clot engaging element configured to extend across the clot in its expanded state, the expandable clot engaging element comprising a first monolithic structure and a second monolithic structure, the first monolithic structure encircling the second monolithic structure over at least a portion of its length, the second monolithic structure comprising a proximal section, an intermediate section and a distal section, the distal section comprising an expansion.
Some optional features of this embodiment include:
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- wherein the first monolithic structure is configured to substantially encapsulate the second monolithic structure;
- wherein the first monolithic structure comprises a proximal section, an intermediate section and a distal section, the distal section comprising an enclosed distal end;
- wherein the distal end of the clot engaging element comprises an enclosed distal end said enclosed distal end configured to capture clot fragments and/or to prevent distal migration of clot fragments;
- wherein the expansion is configured to prevent clot fragment migration;
- wherein the distal end of the first monolithic structure comprises an enclosed distal end said enclosed distal end defining a surface the surface configured as a clot fragment barrier surface;
- wherein the clot fragment barrier surface comprises an interconnected network of struts;
- wherein the distal section of the clot engaging element is configured to provide a three dimensional barrier to clot migration;
- wherein the device further comprises a elongate connector element said elongate connector element comprising a proximal end and a distal end, the proximal end connected to the second monolithic structure and the distal end connected to the first monolithic structure;
- wherein the elongate connector element comprises a spring element and said spring element is integral with the second monolithic structure;
- wherein the first monolithic structure and the second monolithic structure are connected at their distal ends;
- wherein the first monolithic structure and the second monolithic structure are not connected at their distal ends; and/or
- wherein the proximal sections of said first and second monolithic structures are connected to a distal end of the elongate member.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and an expandable clot engaging element configured to extend across the clot in its expanded state, the expandable clot engagement element comprising a proximal segment, a clot engaging segment and a distal segment, the proximal segment configured to extend proximal of the clot in use and the distal end configured to extend distal of the clot in use, the clot engaging segment configured to engage with the clot in its expanded state, the distal end comprising a fragment protection structure, the fragment protection structure comprising a plurality of struts configured in a volumetric pattern.
Some optional features of this embodiment include:
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- wherein the volumetric pattern comprises at least partially a conically shaped volumetric pattern;
- wherein the volumetric pattern comprises at least partially a cylindrical volumetric pattern;
- wherein the volumetric pattern comprises at least one plurality of interconnected struts;
- wherein the volumetric pattern comprises at least two pluralities of interconnected struts;
- wherein the volumetric pattern comprises a first plurality of struts arranged about a first axis and a second plurality of struts arranged about a second axis;
- wherein the position of the first axis is moveable relative to the position of the second axis;
- wherein the first axis and the second axis comprise centre lines and in use said centre lines may comprise straight and/or curved centre lines;
- wherein the centrelines are deflectable relative to one another;
- wherein the volumetric pattern comprises a terminal end;
- wherein the terminal end comprises a terminal junction for at least some of said plurality of struts;
- wherein the terminal end comprises a connection point at which said plurality of struts are terminated and/or connected;
- wherein the volumetric pattern comprises a first plurality of struts, and a second plurality of struts;
- wherein the second plurality of struts is at least partially encompassed by the first plurality of struts;
- wherein the second plurality of struts encircles the first plurality of struts;
- wherein the first plurality of struts is arranged about a first axis and the second plurality of struts is arranged about a second axis and said first and second axes are substantially parallel;
- wherein the first plurality of struts is arranged about a first axis and the second plurality of struts is arranged about a second axis and said first and second axes are substantially parallel;
- wherein the first plurality of struts comprises a conical shape; and or
- wherein the second plurality of struts comprises a spherical shape, a flattened spherical shape, a cylindrical shape or a spindle torus shape.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and an expandable clot engaging element comprising a first tubular structure and a second tubular structure, the first tubular structure at least partially encircling the second tubular structure, the first tubular structure comprising a proximal end, a distal end, a proximal termination and a distal termination, the second tubular structure comprising a proximal end, a distal end, a proximal termination and a distal termination, the proximal termination of the first and second tubular structures being connected to the elongate member and the distal terminations of the first and second tubular structures being connected to each other.
Some optional features of this embodiment include:
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- wherein the first tubular structure and the second tubular structure comprise monolithic structures of interconnected struts;
- wherein the first tubular structure and the second tubular structure comprise longitudinally extending structures;
- wherein both the first tubular structure and the second tubular structure comprise collapsed delivery configurations and expanded deployed configurations and the first tubular structure at least partially encircling the second tubular structure in both the expanded configurations and the collapsed configurations;
- wherein one or both of the first tubular structure and the second tubular structure comprise a proximal collar for connecting one or both of the first tubular structure and the second tubular structure to a distal end of the elongate member;
- wherein the at least one proximal collar comprises a partial collar; and/or
- wherein the at least one proximal collar is cut from a hypotube and encircles at least a portion of a distal end of the elongate member.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and an expandable clot engaging element comprising a first tubular structure and a second tubular structure, the first tubular structure at least partially encircling the second tubular structure, the first tubular structure and the second tubular structure connected to a distal end of the elongate member at a connection point, the first tubular structure comprising a first proximal connecting strut and a first connector element, the second tubular structure comprising a second proximal connecting strut and a second connector element, the first connector element encircling the second connector element at the connection point.
Some optional features of this embodiment include:
-
- wherein the first connector comprises a collar;
- wherein the second connector comprises a collar or partial collar; and/or
- wherein the elongate member comprises a distal safety stop configured to prevent distal movement of the first connector and/or the second connector.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and an expandable clot engaging element configured to extend across the clot in its expanded state, the expandable clot engagement element comprising a first luminal structure and a second luminal structure, the first luminal structure being larger in diameter than said second luminal structure, the distal end of said first luminal structure comprising a plurality of struts converging towards the axis of the first luminal structure, the distal end of said second luminal structure comprising a plurality of struts diverging away from the axis of said second luminal structure.
Some optional features of this embodiment include:
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- wherein the distal end of said first and second luminal structures are configured to form a three dimensional clot fragment migration barrier;
- wherein the distal end of said second luminal structure further comprises an inflection region where a tangent to said plurality of struts is substantially parallel to the axis of said second luminal structure;
- wherein the distal end of said second luminal structure further comprises a converging region where said plurality of struts converged on the axis of said second luminal structure;
- wherein the distal end of said second luminal structure further comprises a second distal junction where said plurality of struts terminate;
- wherein the distal end of said first luminal structure further comprises a first distal junction where said plurality of struts terminate;
- wherein the first distal junction is distal of the second distal junction; and/or
- wherein the first distal junction is connected to the second distal junction by a connector element.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and a clot engaging element comprising a collapsed delivery state and an expanded clot engaging state, the clot engaging element configured to extend across the clot in its expanded state, the clot engaging element comprising a proximal section, an intermediate section and a distal section, the intermediate section comprising a luminal structure and the distal section comprising an expansion region.
Some optional features of this embodiment include:
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- wherein the diameter of the expansion region is larger than the diameter of the intermediate section in the expanded state;
- wherein the clot engagement element comprising plurality of struts connected in a monolithic structure;
- wherein the expansion region comprises a region of divergence and a region of convergence;
- wherein the expansion region comprises an inflection point between the region of divergence and the region of convergence;
- wherein the expansion region is integral with the intermediate section;
- wherein the expansion region comprises a transition section the transition section comprising a plurality of struts connection the expansion region to the intermediate section;
- wherein the expansion region comprises a tapering distal end;
- wherein the device comprises an elongate member connected to the distal end of the expansion region; and/or
- wherein in the expanded state the luminal structure is configured to define a flow lumen through the clot.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and a clot engaging element comprising a collapsed delivery state and an expanded clot engaging state, the clot engaging element configured to extend across the clot in its expanded state, the clot engaging element comprising a proximal section, an intermediate section and a distal section, the proximal section and the intermediate section comprising a luminal structure, the proximal section comprising a smaller diameter than the intermediate section.
Some optional features of this embodiment include:
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- wherein the diameter of the proximal section is less than 60% of the diameter of the intermediate section;
- wherein the diameter of the proximal section is less than 50% of the diameter of the intermediate section;
- wherein the diameter of the proximal section is less than 40% of the diameter of the intermediate section;
- wherein the diameter of the proximal section is less than 30% of the diameter of the intermediate section;
- wherein the diameter of the proximal section is less than 25% of the diameter of the intermediate section;
- wherein the diameter of the proximal section is less than 20% of the diameter of the intermediate section;
- wherein the proximal section comprises a proximal axis and the distal section comprises a distal axis and the proximal axis is offset relative to the distal axis in the expanded state.
- wherein the proximal section comprises a first sub-structure and the intermediate section comprises a second sub-structure;
- wherein the luminal structure of proximal section extends through the luminal structure of the intermediate section;
- wherein the luminal structure of proximal section interconnects with the luminal structure of the intermediate section;
- wherein the clot engaging element comprises a transition section interspersed between proximal section and the intermediate section and configured to provide a smooth transition between the proximal section and the intermediate section; and/or
- wherein the distal section comprises a plurality of struts configured in a closed distal end.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising: an elongate member, and an expandable clot engaging element configured to extend across the clot in its expanded state, the expandable clot engagement element comprising a first luminal structure and a second luminal structure, the first luminal structure being larger in diameter than said second luminal structure and encircling at least a portion of the second luminal structure, the second luminal structure extending substantially proximal of the first luminal structure.
Some optional features of this embodiment include:
-
- wherein the first luminal structure comprises a proximal section, an intermediate section and a distal section and the second luminal structure comprises a proximal section, an intermediate section and a distal section;
- wherein the intermediate section of the second luminal structure extends substantially proximal of the intermediate section of the first luminal structure;
- wherein the proximal section of the second luminal structure comprises a connection to a distal end of the elongate member;
- wherein the proximal section of the first luminal structure comprises a connection to a distal end of the elongate member;
- wherein the proximal section of the first luminal structure comprises a connection to the second luminal structure;
- wherein the proximal section of the first luminal structure comprises a connector extending from the intermediate section to a connection point with the elongate member; and/or
- wherein the connection point with the elongate member is proximal of the second luminal structure.
In another embodiment of the invention the treatment apparatus comprises a device for removing clot from a blood vessel comprising: an elongate member, and an expandable clot engaging element configured to extend across the clot in its expanded state, the expandable clot engagement element comprising a first luminal structure and a second luminal structure, the first luminal structure being larger in diameter than said second luminal structure and encircling at least a portion of the second luminal structure, the second luminal structure comprising a clot capture structure at its distal end, the clot capture structure comprising a flared section.
Some optional features of this embodiment include:
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- wherein the clot capture structure comprises a plurality of struts and at least one fibre configured into a filter;
- wherein in the expanded state the diameter of at least a portion of the clot capture structure is similar to the diameter of the blood vessel;
- wherein in the expanded state the diameter of at least a portion of the clot capture structure is larger than the diameter of the second luminal structure; and/or
- wherein in the expanded state the diameter of at least a portion of the clot capture structure is similar to the diameter of the first luminal structure.
In another embodiment of the invention the treatment apparatus comprises a clot retrieval device comprising an elongate member, a first expandable member and a second expandable member; both expandable members having a proximal section, a body section, and a distal section, the body section of the first expandable member in the freely expanded state being larger in diameter than that of the second expandable member in the freely expanded state, and the proximal section of the first expandable member being distal of the proximal section of the second expandable member.
Some optional features of this embodiment include:
-
- wherein the distal section of the first expandable member comprises a clot capture structure;
- wherein the distal section of the second expandable member comprises a clot capture structure;
- wherein the clot capture structure comprises a plurality of struts;
- wherein the clot capture structure comprises a plurality of struts and at least one fibre configured into a filter;
- wherein the proximal end of the first expandable member is connected to the distal section of the elongate shaft;
- wherein the proximal end of the first expandable member is connected to the second expandable member;
- wherein the proximal end of the second expandable member is connected to the distal section of the elongate shaft;
- wherein the distal end of the first expandable member is not connected to the distal end of the second expandable member;
- wherein the distal end of the first expandable member is connected to the distal end of the second expandable member;
- wherein the body section of the second expandable member in the freely expanded state is less than 50% of the diameter of the body section of the first expandable member in the freely expanded state;
- wherein the body section of the second expandable member in the freely expanded state is less than 40% of the diameter of the body section of the first expandable member in the freely expanded state;
- wherein the body section of the second expandable member in the freely expanded state is less than 30% of the diameter of the body section of the first expandable member in the freely expanded state; and/or
- wherein the body section of the second expandable member in the freely expanded state is less than 20% of the diameter of the body section of the first expandable member in the freely expanded state.
A method of using a clot retrieval device to retrieve a clot from a vessel, said clot retrieval device comprising an expandable body and an elongate shaft, said method comprising: delivering the device through a microcatheter to a target site, retracting the microcatheter to deploy the device at least partially within or beneath the clot, expanding a proximal section of the expandable member within a proximal section of the clot to a diameter smaller than that of the vessel, expanding a distal section of the expandable member distal of the clot to a diameter substantially equal to that of the vessel, withdrawing the device and clot proximally and removing both from the patient.
Some optional features of this embodiment include:
-
- wherein the expandable body comprises an inner expandable member and an outer expandable member;
- wherein the expanded diameter of the inner expandable member is smaller than that of the outer expandable member;
- wherein at least a portion of the inner expandable member extends within at least a portion of the outer expandable member;
- wherein at least a portion of the inner expandable member extends proximal of the outer expandable member;
- wherein the distal section of the expandable body comprises a clot capture structure;
- wherein the clot capture structure is connected to the inner expandable member;
- wherein the clot capture structure is connected to the outer expandable member; and/or
- wherein the elongate shaft extends outside of the patient in use.
A clot retrieval device for removing occlusive clot from a blood vessel, the device comprising: an elongate shaft; an inner elongate body having a collapsed delivery configuration and an expanded deployed configuration; an outer elongate body at least partially overlying the inner elongate body; the outer elongate body being expandable relative to the inner elongate body to a radial extent which is greater than the radial extent of the inner body in the deployed configuration; the proximal end of the outer elongate body being detachably fixed to the distal end of the elongate shaft.
Some optional features of this embodiment include:
-
- wherein the proximal end of the outer elongate body comprises two or more struts;
- wherein detachment of the proximal end of the outer elongate body from the distal end of the elongate shaft frees the proximal struts to expand apart;
- wherein the outer elongate body adopts a substantially cylindrical or tubular shape upon detachment;
- wherein the outer elongate body further comprises a closed distal clot capture structure comprising a plurality of struts converging at a terminal connection;
- wherein the distal end of said plurality of struts are detachable from the terminal connection;
- wherein detachment of said plurality of struts from the terminal connection frees the struts to expand apart;
- wherein the device further comprises a detachment system; and/or
- wherein the detachment system comprises a pull-wire, a bio-absorbable collar or fibre, an electrolytic system or a resistance heating system.
The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:
Specific embodiments of the present invention are now described in detail with reference to the figures, wherein identical reference numbers indicate identical or functionality similar elements. The terms “distal” or “proximal” are used in the following description with respect to a position or direction relative to the treating physician. “Distal” or “distally” are a position distant from or in a direction away from the physician. “Proximal” or “proximally” or “proximate” are a position near or in a direction toward the physician.
Accessing cerebral, coronary and pulmonary vessels involves the use of a number of commercially available products and conventional procedural steps. Access products such as guidewires, guide catheters, angiographic catheters and microcatheters are described elsewhere and are regularly used in cath lab procedures. It is assumed in the descriptions below that these products and methods are employed in conjunction with the device and methods of this invention and do not need to be described in detail.
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Although the description of the invention is in many cases in the context of treatment of intracranial arteries, the invention may also be used in other body passageways as previously described.
A common theme across many of the disclosed designs is a dual layer construction in which the device comprises an outer expandable member within which runs an inner expandable member, both members being directly or indirectly connected to an elongate shaft, and a distal net or scaffold configured at the distal end of the device to prevent the escape of clot fragments. This distal net may be appended to either the shaft, the inner or the outer members or to several of these. A range of designs are envisaged for each of these elements as described throughout this document, and it is intended that any of these elements could be used in conjunction with any other element, although to avoid repetition they are not shown in every possible combination. For example it is intended that the outer expandable member/outer cage of
Both the inner and outer expandable members are desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material such as Nitinol or an alloy of similar properties is particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable 30 manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure to create a framework of struts and connecting elements. This framework can be any of a huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements (such as Platinum for example) or through a variety of other coatings or marker bands.
The inner expandable member may in some cases form a generally tubular structure and is ideally configured to expand to a lesser diameter than that of the smallest vessel in which it is intended to be used. This diameter is typically less than 50% that of the outer expandable member may be as low as 20% or less of the outer member diameter.
A range of different distal net or distal scaffolding zone designs are disclosed, some of which incorporate strut elements from the framework of the outer and/or inner expandable members, and some of which incorporate fine wires or fibres to provide added scaffolding with minimal impact of overall device profile or deliverability. Suitable materials ideally have a high tensile strength so that a very fine wire or fibre with sufficient integrity for manufacturability and use can be produced, such as for example polymers materials like UHMWPE, Aramid, LCP, PET or PEN, or metals such as Tungsten, MP35N, stainless steel or Nitinol.
The inner and outer members are preferably made of a super-elastic or pseudo-elastic material such as Nitinol or another such alloy with a high recoverable strain. Shaft 6 may be a tapered wire shaft, and may be made of stainless steel, MP35N, Nitinol or other material of a suitably high modulus and tensile strength. Shaft 6 may have indicator bands 7 on the shaft to indicate to the user when the distal end of the device is approaching the end of the microcatheter during insertion. These bands are positioned so that as they approach the microcatheter hub or haemostasis valve they indicate the distal tip of the device is approaching the end of the microcatheter. These indicator bands can be formed by printing or removing or masking areas of shaft coating so that they are visually differentiated from the remainder of the shaft. In another embodiment the indicator bands 7 are recessed below the surface of the shaft to give tactile feedback to the user as they approach the microcatheter.
Shaft 6 has a coil 4 adjacent its distal end and proximal of the outer member 2 and inner tubular member 3. This coil 4 may be metallic and may be formed from stainless steel or from a more radiopaque material such as platinum or gold for example or an alloy of such a material. In another embodiment the coil 4 may be coated with a low friction material or have a polymeric jacket positioned on the outer surface of the coil. Adjacent to this coil 4 a sleeve 5 may be positioned on the shaft 6. This sleeve 5 may be polymeric and may be positioned over the tapered section of the shaft. The sleeve 5 may be rendered radiopaque through the addition of a filler material such as tungsten or barium sulphate. The sleeve 5 and shaft 6 may be coated with a material to reduce friction and thrombogenicity. The coating may consist of a polymer, a low friction lubricant such as silicon, a hydrophilic or a hydrophobic coating. This coating may also be applied to the outer member 2 and inner tubular member 3.
Referring especially to
The collar of the outer member 12 is eccentric to the shaft 6 therefore in this embodiment a strut 14 is formed attached to the partial collar of the inner member 13. This strut 14 projects proximally and acts as a locating element for the proximal coil 4. When the proximal radiopaque coil 4 is located on the proximal strut 14 and the shaft 6, the coil is substantially concentric with the collar 12 of the outer member. Adhesive may be applied to the joint between the proximal coil and outer member collar to maintain the joint integrity. In another embodiment a solder, brazing or weld process may be used in this joint.
The outer member 2 is configured to self-expand upon release from a restraining sheath (such as a microcatheter) to a diameter larger than that of the inner tubular member 3. Expansion of the outer member 2 causes compression and/or displacement of the clot during expansion. When an expandable body provides a high level of scaffolding the clot is compressed. When an expandable body provides an escape path or opening the expanding body will urge the clot towards the opening. However if the expandable body provides only modest scaffolding the clot will be displaced but since the clot has many degrees of freedom it may move in a variety of different directions and therefore cannot be controlled. By providing a tubular expandable body where the length of the tubular expandable body is substantially as long as the length of the occlusive clot or longer, many of the degrees of movement freedom available to the clot are removed. When, as with the current invention, inlet openings 22 (as illustrated for example in
Outer member 2 comprises proximal struts 20 connected at their proximal ends to a collar 12 and at their distal ends to a first expandable member 26. The proximal struts 20 may have a tapered profile to ensure a gradual stiffness transition from the shaft 6 to the clot engagement section of the device. The first expandable member 26 is connected to a second expandable member 27 by two connecting arms 29, which run from a proximal junction 39 to a distal junction 40. In one embodiment these connecting arms comprise generally straight struts running parallel to the central axis of the device. In other embodiments these connecting arms may comprise a plurality of struts configured in one or more cells, or may comprise curved or spiral arms. The region between the first and second expandable member comprises two inlet mouths 22 through which clot may pass and enter the reception space 11 defined by the region between the inner and outer members.
The second expandable member 27 is in turn connected to a third expandable member 28 by two connecting arms 30, which run from a proximal junction 41 to a distal junction 42. In one embodiment these connecting arms comprise generally straight struts running parallel to the central axis of the device. In other embodiments these connecting arms may comprise a plurality of struts configured in one or more cells, or may comprise curved or spiral arms. The region between the second and third expandable member comprises two inlet mouths 22 through which clot may pass and enter the reception space 11 defined by the region between the inner and outer members. The connecting arms between the first expandable member 26 and the second expandable member 27 may be substantially aligned with the connecting arms between the second and third expandable members 27,28 to align the neutral axis of the expandable members 26,27,28 during bending. In another embodiment the connecting arms between the first expandable member 26 and the second expandable member 27 may be aligned at an angle, such as 90° to the connecting arms between the second and third expandable members 27,28.
The first expandable member 26 comprises a series of interconnected struts, with certain struts such as strut 43 terminating in crowns with no distal connecting elements, and other struts such as 44 terminating in junction points such as 45 and 46. The second expandable member 27 comprises a series of interconnected struts, with certain struts such as strut 47 terminating in crowns with no distal connecting elements, and other struts such as 48 terminating in junction points. One or more expandable members may comprise marker bands or radiopaque features such as gold or platinum marker or coils. In this embodiment a gold oval marker 25 is shown fixed in an eyelet on a strut in the third expandable member 28. The gold marker is positioned to indicate to the user the distal end of the barrel section of the outer member to aid in accuracy of deployment. The struts in the expandable members may be configured so that during loading, multiple crowns do not align at the same distance from the proximal collar, for example 45 and 50. During loading or resheathing, a higher force is generally required to load a crown than a strut into the sheath, therefore if multiple crowns are loaded at the same time the user may notice an increase in loading force. By offsetting the crowns by making alternative struts 44 and 51 different lengths the loading force may be reduced and the perception to the user is improved.
The distal end of the third expandable member 24 comprises a circumferential ring of struts 23 connected to a series of struts 24 that ultimately terminate at a distal junction point 9, thus defining a closed end to the outer member. This series of struts may comprise a generally conical shape as shown in
Inner tubular member 3 comprises a generally cylindrical section of interconnected struts 31, which is connected at its proximal end by strut 34 to partial collar 13. The distal end of the inner tubular member 3 consists of an expansile section formed from expanded struts 10 which have a diameter greater than that of the body section of the inner tubular member 3. These expanded struts are connected to a coil section 18 which in this embodiment is laser cut from the tubing that the inner tubular member 3 is also cut from during processing. The distal end of the coil 18 has a castellated profile 35 which is joined to the distal collar 9 of the outer member 2 during assembly. The distal end of the coil 18 on the inner tubular member 3 is bonded to the distal collar of the outer member 2 by adhesive. The castellated feature 35 on the inner tubular member 3 facilitates this adhesive bond and improves the strength of the bond by providing a reception space 38 for the adhesive within the collar and preventing it from wicking into the coil area. In another embodiment this joint may be assembled using a solder, weld or braze process.
The outer member 2 and the inner tubular member 3 are joined at the proximal and distal ends during assembly thereof to minimise tension within the members during use, the length of the outer member 2 should be substantially the same as the length of the inner tubular member 3 in the freely expanded configuration and the loaded configuration. The expanded struts 10 of the inner tubular member 3 elongate during loading so that the lengths of the inner and outer members are equal when fully loaded in a microcatheter. Length differentials between the inner tubular member 3 and the outer member 2 can still occur when the device is deployed in a small vessel or during the loading or deployment process. The coil 18 at the distal end of the inner tubular member 3 can accommodate minor length differentials by stretching without applying significant tensile or compressive forces to the device. In another embodiment this coil could be formed separately to the inner tubular member 3 and then be assembled to it. The coil could be formed from a stainless steel material, a polymer or from a more radiopaque metal such as gold or platinum or an alloy of such a material. The coil could also be replaced with a longitudinal length of an elastic material such as a low modulus polymer or elastomer.
In other embodiments the inner tubular member may not be connected to the distal end of the outer member at all, or may be constrained within the outer member without being fixedly attached. In other embodiments the inner tubular member may have a non-cylindrical cross-section, may be non-uniform in diameter, and may have tailored strut patterns to provide regions of differing radial force or flexibility.
An isometric view of the distal end of another embodiment of a clot retrieval device similar to device 1 is shown in
An isometric view of the distal end of another embodiment of a clot retrieval device similar to device 1 is shown in
Another embodiment of the device is shown in
Referring now to
Each of the shaft and inner and outer expandable members may be constructed in a variety of manners as disclosed herein. This dual layer construction is intended to allow clot to enter through the large openings 161 of the outer expandable member and sit in the reception space 162 provided between the two expandable members. The inner member has a denser scaffold than that of the outer such that the clot is prevented from entering its lumen, thus creating a flow channel across the clot once the device is deployed across it. The long proximal portion of the inner member can be constructed with a very small volume of material, as it only expands to a fraction of the diameter of the outer member, and can thus be highly flexible in both the collapsed and expanded states. A significant benefit of this proximally extending member is that it allows a flow channel to be created across very long clots without overly compressing the clot or engaging with the vessel wall.
The distal scaffolding zone may comprise a generally conical tapering of the distal end of the outer member defined by a plurality of strut elements. In one embodiment one or more fibres are attached to the distal region of the outer member to increase the scaffolding by reducing the pore size of the openings in a manner similar to that shown in
The outer expandable member 204 comprises clot scaffolding regions 210 and inlet openings 211 such that clot is urged by the scaffolding regions to flow through the openings into the reception space 212 between inner and outer members as described in more detail elsewhere.
In other embodiments the inner and outer members and distal net may comprise any of the designs disclosed elsewhere herein for these elements. In this embodiment connecting arms 206 of the outer member pass through openings in the framework of inner member 203 and join to the shaft, while in other embodiments the outer member may be attached directly to the inner member. In yet another embodiment the portion of the inner expandable member proximal to the outer expandable member may be formed from the same piece of material (for example a single piece of nitinol tubing) as the outer expandable member, and the portion of the inner expandable member distal to the proximal end of the outer expandable member may be formed from a separate piece of material.
In the embodiment shown the compliance of the inner member is made possible by the design of the framework of struts and connectors from which this member is formed. The inner member illustrated in
In yet another embodiment the inner member is constructed in a similar fashion to that described above except that the connectors alternate in direction between each adjacent ring—for example all of the connectors between the first and second rings may be oriented clockwise, while all of the connectors between the second and third rings may be oriented anticlockwise. Thus when the device expands or contracts each ring twists relative to its adjacent ring, but each twist counterbalance the next so that minimal twisting occurs to the distal end of the inner member relative to the proximal end.
In yet another embodiment the inner member comprises a closed cell pattern of cells, each cell bounded by struts, and the cells configured in a generally spiral pattern around the circumference of the member.
In another embodiment the inner member comprises a braided structure, formed from one or more wires. The braided structure comprises a series of opposing spirals, with multiple overlap points where one wire crosses over another. At least some of these crossover points are not fixed attachment points, so that the member can easily accommodate a bend by a sliding action of one wire over another at these crossovers.
In yet another embodiment the inner member comprises an open cell framework of struts and connectors.
In the embodiment shown the proximal joint 657 is generally concentric with the device and is radially displaced from the side wall of the vessel. Therefore the proximal struts 662 would obstruct the vessel lumen if left unaltered, causing potential recrossing difficulties and acting as a potential nidus for future clot formation. To address this issue the proximal terminations 652 separate upon detachment from the proximal joint 657, freeing the proximal struts (which are heat set to remember a preferred radially outwardly projecting configuration) to expand and appose the vessel wall or clot. A variety of means can be employed to detach the proximal joint and terminations, including: electrolytically, resistance heating of a low melt joining material, or other mechanical pull-wire or twisting mechanism. An example of a pull wire joint is shown in
In one embodiment the distal terminations 655 are held together by a bioabsorbable fibre or collar, which is configured to dissolve after a period of time in contact with blood and thus allow the terminations to separate and the distal cone to expand towards a cylindrical shape and appose the vessel wall. This time period is ideally greater than 30 minutes and less than 7 days, and is most preferably between 1 and 3 hours. In other embodiments the distal joint is connected to the distal end 661 of the inner expandable member in such a way that retraction of the inner expandable member relative to the outer expandable member disconnects the distal joint and allows the distal cone of the outer member to expand. In yet other embodiments the distal terminations are released by means similar to that described above for the release of the proximal terminations.
The method of use is similar to that described in relation to
The distribution of the large inlet windows and smaller cells is key to the performance of the device and in this configuration the large inlet windows and smaller scaffolded cells are generally alternated along the length of the device, for example large cell 973 is adjacent to smaller cell 977 which is adjacent to larger cell 978 which is adjacent to smaller cell 980, along the length of the device. In this configuration the larger inlet windows and pairs of smaller scaffolded cells are also generally alternated radially around the circumference of the device. For example large inlet window 978 is adjacent to smaller cells 981 and 982 which are adjacent to large inlet window 983 around the circumference of the outer member.
In this embodiment the proximal struts 971 are connected to a ring of smaller scaffolded cells 972 around the proximal end of the outer member. The distal end of the body section may be connected to a ring of struts 974 that provide sufficient radial force to prevent the movement of clot past the distal end of the device during retraction in the vessel. The distal ring of struts 974 is connected to a series of struts 975 which form a closed end on the outer member and terminate at the distal collar 976.
It will be apparent from the foregoing description that, while particular embodiments of the present invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the present invention be limited and should be defined only in accordance with the appended claims and their equivalents.
Claims
1-24. (canceled)
25. A clot retrieval device for removing clot from a blood vessel, the device having a collapsed delivery configuration and an expanded deployed configuration and comprising:
- an inner expandable body; and
- an outer expandable body having a closed distal end and at least partially overlying the inner expandable body, the outer expandable body being expandable to a radial extent which is greater than the radial extent of the inner expandable body in the deployed configuration to provide a clot reception space radially between the inner expandable body and the outer expandable body;
- wherein each of the inner expandable body and the outer expandable body includes a plurality of struts and a porosity provided by the struts of the inner expandable body is less than a porosity provided by the plurality of struts of the outer expandable body.
26. The device of claim 25, wherein the outer expandable body extends distally of the inner expandable body.
27. The device of claim 25, wherein the inner expandable body includes a main body portion and a distal strut portion, wherein the distal strut portion is expandable to a radial extent which is greater than the extent of the main body portion in the deployed configuration.
28. The device of claim 27, wherein the main body portion is generally tubular.
29. The device of claim 25, wherein each of the inner expandable body and the outer expandable body are comprised of self-expandable material.
30. The device of claim 25, wherein the outer expandable body defines at least one clot inlet mouth extending through the outer expandable body and into the clot reception space.
31. The device of claim 30, wherein the plurality of struts of the outer expandable body include a plurality of scaffolding segments, wherein the at least one clot inlet mouth is positioned between adjacent scaffolding segments.
32. The device of claim 25, further including an elongate member, wherein a proximal end of each of the outer expandable body and the inner expandable body are coupled to a distal portion of the elongate member.
33. The device of claim 25, wherein the plurality of struts of the outer expandable body are arranged in a non-uniform strut pattern.
34. The device of claim 33, wherein the plurality of struts of the inner expandable body are arranged in a uniform strut pattern.
35. A clot retrieval device for removing clot from a blood vessel, the device having a collapsed delivery configuration and an expanded deployed configuration and comprising:
- an inner expandable body; and
- an outer expandable body at least partially overlying the inner expandable body and including a plurality of scaffolding segments and at least one clot inlet mouth between adjacent scaffolding segments, the outer expandable body being expandable to a radial extent which is greater than the radial extent of the inner expandable body in the deployed configuration to provide a clot reception space radially between the inner expandable body and the outer expandable body;
- wherein each of the inner expandable body and the outer expandable body includes a plurality of struts, wherein a porosity provided by the plurality of struts of the inner expandable body is less than a porosity provided by the plurality of the struts of the outer expandable body.
36. The device of claim 35, wherein the outer expandable body includes a closed distal end.
37. The device of claim 35, wherein each of the inner expandable body and the outer expandable body are comprised of self-expandable material.
38. The device of claim 35, wherein the inner expandable body includes a main body portion and a distal strut portion, wherein the distal strut portion is expandable to a radial extent which is greater than the extent of the main body portion in the deployed configuration, and wherein the main body portion is generally tubular.
39. A clot retrieval device for removing clot from a blood vessel, the device having a collapsed delivery configuration and an expanded deployed configuration and comprising:
- an inner expandable body including a plurality of struts arranged in a uniform strut pattern; and
- an outer expandable body and at least partially overlying the inner expandable body, the outer expandable body including a plurality of struts arranged in a non-uniform strut pattern, the outer expandable body being expandable to a radial extent which is greater than the radial extent of the inner expandable body in the deployed configuration to provide a clot reception space radially between the inner expandable body and the outer expandable body;
- wherein a porosity provided by the plurality of struts of the inner expandable body is less than a porosity provided by the plurality of struts of the outer expandable body.
40. The device of claim 39, wherein the outer expandable body includes a closed distal end.
41. The device of claim 39, wherein each of the inner expandable body and the outer expandable body are comprised of self-expandable material.
42. The device of claim 39, wherein the outer expandable body defines at least one clot inlet mouth extending through the outer expandable body and into the clot reception space.
43. The device of claim 39, wherein the plurality of struts of the outer expandable body include a plurality of scaffolding segments, wherein the at least one clot inlet mouth is positioned between adjacent scaffolding segments.
44. The device of claim 15, wherein a distal net structure is included at the distal end of the outer expandable body.
Type: Application
Filed: Dec 31, 2015
Publication Date: Apr 28, 2016
Applicant: Neuravi Limited (Galway)
Inventors: Eamon BRADY (County Galway), Brendan CASEY (Galway), Michael GILVARRY (County Galway), David HARDIMAN (Dublin 5), Kevin McARDLE (County Galway), Mahmood RAZAVI (Irvine, CA), David VALE (County Galway)
Application Number: 14/985,628
