Patent Application
20230363775
The present invention generally relates to devices and methods for removing acute blockages from blood vessels during intravascular medical treatments. More specifically, the present invention relates to retrieval catheters with expandable tips into which an object or objects can be retrieved.
Clot retrieval aspiration catheters and devices are used in mechanical thrombectomy for endovascular intervention, often in cases where patients are suffering from conditions such as acute ischemic stroke (AIS), myocardial infarction (MI), and pulmonary embolism (PE). Accessing the neurovascular bed in particular is challenging with conventional technology, as the target vessels are small in diameter, remote relative to the site of insertion, and highly tortuous. Traditional devices are often either too large in profile, lack the deliverability and flexibility needed to navigate particularly tortuous vessels, or are ineffective at removing a clot when delivered to the target site.
Many existing designs for aspiration retrieval catheters are often restricted to, for example, inner diameters of 6Fr or between approximately 0.068 to 0.074 inches. Larger sizes require an even larger guide or sheath to be used, which then necessitates a larger femoral access hole to close. Most physicians would prefer to use an 8F guide/6F sheath combination, and few would be comfortable going beyond a 9F guide/7F sheath combination. This means that once at the target site, a clot can often be larger in size than the inner diameter of the aspiration catheter and must otherwise be compressed to enter the catheter mouth. This compression can lead to bunching up and subsequent shearing of the clot during retrieval. Firm, fibrin-rich clots can also become lodged in the fixed-mouth tip of these catheters making them more difficult to extract. This lodging can result in softer portions breaking away from firmer regions of the clot.
Small diameters and fixed tip sizes are also less efficient at directing the aspiration necessary to remove blood and thrombus material during the procedure. The suction must be strong enough such that any fragmentation that may occur as a result of aspiration or the use of a mechanical thrombectomy device cannot migrate and occlude distal vessels. When aspirating with a fixed-mouth catheter, a significant portion of the aspiration flow ends up coming from vessel fluid proximal to the tip of the catheter, where there is no clot. This significantly reduces aspiration efficiency, lowering the success rate of clot removal.
Intermediate- and aspiration-catheters and/or those with expandable tips are therefore desirable because they provide a large lumen and distal mouth to accept a clot with minimal resistance. However, current designs with fixed braids, frames, or expanded sizes do not allow for any additional expansion of the tip which can complicate the interaction with and reception of a clot during ingestion.
It is an object of the present designs to provide devices and methods to meet the above-stated needs. The designs can be for a clot retrieval catheter capable of remove a clot from cerebral arteries in patients suffering AIS, from coronary native or graft vessels in patients suffering from MI, and from pulmonary arteries in patients suffering from PE and from other peripheral arterial and venous vessels in which a clot is causing an occlusion.
One example of the present disclosure provides a catheter. The catheter can include an elongate body having a longitudinal axis, an inner diameter, and a distal end. The catheter can include a support frame connected at the distal end of the elongate body. The support frame can have a collapsed delivery configuration, an expanded deployed configuration, and a framework of struts including a plurality of distal hoop segments. At least a portion of the distal hoop segments can fold distally in the collapsed delivery configuration such that a collapsed inner diameter of the support frame is approximately equal to the inner diameter of the elongate body. The support frame can have a maximum outer diameter in the expanded deployed configuration. The maximum outer diameter can be less than an inner diameter of a target vessel at a treatment site.
A first more distal hoop segment of the plurality of distal hoop segments can have a first diameter when the support frame is in the expanded deployed configuration, and a second more proximal hoop segment of the plurality of distal hoop segments can form a second diameter when the support frame is in the expanded deployed configuration. The first diameter can be greater than the second diameter.
The struts of the distal hoop segments can have a curvilinear profile in the collapsed delivery configuration.
The support frame can have a longitudinal length sized to be less than three times the inner diameter of the elongate body.
The catheter can include one or more connecting spines connecting the distal hoop segments of the support frame with the elongate body.
The plurality of distal hoop segments can fold so the support frame has a collapsed inner diameter in the collapsed delivery configuration approximately equal to the inner diameter of the elongate body.
The plurality of distal hoop segments can include distally unconnected peaks which move distally when the support frame is folded to the collapsed delivery configuration.
The distally unconnected peaks can move proximally when the support frame is in the expanded deployed configuration.
A first more distal hoop segment of the plurality of distal hoop segments can form a first folded angle with respect to the longitudinal axis when the support frame is in the collapsed delivery configuration. A second more proximal hoop segment of the plurality of distal hoop segments can form a second folded angle with respect to the longitudinal axis when the support frame is in the collapsed delivery configuration. The first folded angle can be less than the second folded angle.
The plurality of distal hoop segments can form a series of rings concentric with the longitudinal axis when the support frame is in the expanded deployed configuration.
At least a portion of each of the plurality of distal hoop segments can form an acute angle with respect to the longitudinal axis when the support frame is in the collapsed delivery configuration.
Each hoop segment of the plurality of distal hoop segments can have a non-planar cross section when the support frame is in the collapsed delivery configuration.
One or more hoops of the plurality of distal hoop segments can include one or more axial curves when the support frame is in the collapsed delivery configuration.
The support frame can include a plurality of ribs and one or more axial spines. At least one of the one or more axial spines can be aligned with a connecting spine of the support frame.
Another example of the present disclosure provides a catheter. The catheter can have a longitudinal axis. The catheter can include a support frame having a collapsed delivery configuration, an expanded deployed configuration, and a framework of struts including one or more pairs of opposing C-shaped petals. Each pair of opposing C-shaped petals can include a proximal petal and a distal petal. The proximal petal and the distal petal can be folded to an axially-elongated profile in the collapsed delivery configuration. The support frame can have a maximum outer diameter in the expanded deployed configuration. The maximum outer diameter can be less than an inner diameter of a target vessel at a treatment site.
The opposing C-shaped petals can be located (clocked) at 90 degrees to one another.
The opposing C-shaped petals can include distally unconnected peaks.
At least one of the distally unconnected peaks can include a circumferential undulation.
At least one of the opposing C-shaped petals can include an intermediate hoop.
The support frame further can include a proximal ring member connected to a distal end of an elongate body of the catheter.
The plurality of distal hoop segments can have a planar cross section in the expanded deployed configuration.
The support frame can have a collapsed length in the collapsed delivery configuration and an expanded length in the expanded deployed configuration. The collapsed length can be greater than the expanded length.
At least one hoop segment of the plurality of distal hoop segments can define a plane passing through at least a portion of a perimeter of the hoop segment. The plane can form an acute angle with respect to the longitudinal axis when the distal end is in the collapsed delivery configuration.
The distal end of the support frame in the expanded deployed configuration can have a circular profile including a center radially offset from the longitudinal axis of the elongate body.
In some examples, the hoop segments themselves can form cells of the support frame and can bend proximally or distally to fold to a smaller diameter in the collapsed delivery configuration. In one example, the hoop segments can be one or more pairs of opposing C-shaped petals which can be heat set or sprung to expand radially outward when the expandable tip is deployed. In another example, the hoop segments form two longitudinally-opposed rows connected by one or more axial spines. In a further example, the hoop segments can be in the shape of broad loops joined by a single axial spine.
In these examples, when the frame is expanded and the hoops flex radially outward, a first radial size of a more distal hoop or pair of opposing hoops can be greater than a second radial size of an adjacent, more proximal hoop or set of opposing hoops. This can allow the expanded frame to form a substantially funnel shape as the radial size is incrementally increased in more distal hoops. In other examples, at least one of the one or more hoop segments can have a distal peak that does not share a connection with another hoop segment, allowing for independent flexing and a greater range of motion.
Other aspects of the present disclosure will become apparent upon reviewing the following detailed description in conjunction with the accompanying figures. Additional features or manufacturing and use steps can be included as would be appreciated and understood by a person of ordinary skill in the art.
The above and further aspects of this invention are further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention. The figures depict one or more implementations of the inventive devices, by way of example only, not by way of limitation. It is expected that those of skill in the art can conceive of and combine elements from multiple figures to better suit the needs of the user.
Specific examples of the present invention are now described in detail with reference to the Figures, where identical reference numbers indicate elements which are functionally similar or identical. The examples address many of the deficiencies associated with traditional clot retrieval aspiration catheters, such as poor or inaccurate deployment to a target site and ineffective clot removal.
The designs herein can be for a clot retrieval catheter with a lumen and a distal tip that can expand to a diameter larger than that of the guide or sheath through which it is delivered when advanced beyond the distal end. The designs can have a proximal elongate body for the shaft of the catheter, and a distal tip with an expanding support frame and, in some examples, a jacket (e.g., a polymeric jacket) to give the tip atraumatic properties and the ability to flexibly expand further in the expanded deployed configuration when ingesting a clot. The catheter frame and tip can be sufficiently flexible to navigate highly tortuous areas of the anatomy and be able to recover and maintain the inner diameter of the lumen when displaced in a vessel.
Accessing the various vessels within the vascular, whether they are coronary, pulmonary, or cerebral, involves well-known procedural steps and the use of a number of conventional, commercially-available accessory products. These products, such as angiographic materials, mechanical thrombectomy devices, microcatheters, and guidewires are widely used in laboratory and medical procedures. When these products are employed in conjunction with the devices in the description below, their function and exact constitution are not described in detail. While the description is in many cases in the context of thrombectomy treatments in intercranial arteries, the disclosure may be adapted for other procedures and in other body passageways as well.
Turning to the figures,
The clot retrieval catheter 100 can have a flexible elongate body 110 serving as a shaft with a large internal bore (which in some cases can be 0.080 inches or larger) and a distal tip section having a collapsible support frame 210. They can help the catheter to be delivered to a target site by a variety of methods, including over a guidewire, over a microcatheter, with a dilator/access tool, or by itself.
In many cases, the design of the tip of the support frame 210 can be configured so that the entire catheter 100 can be delivered through (and retrieved back through) common standard 6F sheaths/8F guides, which typically have inner lumens of less than 0.090 inches. The tip can self-expand once advanced to an unconstrained position distal to the distal end 32 of the guide sheath 30. As the catheter can be deployed proximal to, and can then be advanced independently to, a remote occlusion, the support frame 210 of the tip is designed to resist collapse from the forces of aspiration, have excellent lateral flexibility in both the expanded and collapsed states, and an atraumatic profile to prevent snagging on bifurcations in vessels.
The structure for the elongate body 110 can define the catheter lumen, which can be used for the delivery of auxiliary devices, contrast injection, and direct distal aspiration to a clot face through the support frame 210. The underlying structure of the elongate body 110 can be, for example, a frame cut from a hypotube of a superelastic material with shape memory properties, such as Nitinol with an internal low friction liner and outer polymer jacket or jackets 180 that can be reflowed into the structure during manufacturing. Alternately, a more traditional polymer and/or metal braid or coil support structure can be used, or some combination of these.
The outer surface of the elongate body 110 and support frame 210 can be at least partially covered by a jacket or jackets 180.
As mentioned, the elongate body 110 can be sized to be compatible with relatively low-profile guide sheaths 30 and catheters, so that a puncture wound in the patient's groin (in the case of femoral access) can be easily and reliably closed. For example, the clot retrieval catheter 100 may be required to pass through the lumen of a guide sheath 30 with an inner diameter of less than 0.110 inches, for example 0.090 inches, or in some cases less than 0.087 inches, and preferably less than 0.085 inches. In other examples with a 5Fr sheath, the inner diameter can be less than 0.080 inches and can be as small as 0.070 inches. Therefore, the catheter 100 can have an overall delivery profile with an inner diameter 115 of approximately 0.067-0.074 inches (0.084 inch or 2 mm outer diameter), and yet be able to expand its distal tip and mouth at the support frame 210 to a size just smaller than the diameter of the vessel approximate where the clot is located, which can be as large as 5 mm. It will be appreciated that larger or smaller catheter shafts can be used if paired with a larger or smaller guide sheath 30.
The support frame 210 can similarly be sized for compatibility. The support frame 210 can have an inner diameter in the collapsed delivery configuration sized so that radial forces are not excessively high for delivery through the selected guide sheath 30, which can for example have an inner diameter of 0.085 inches. Once deployed beyond the distal end 32 of the guide sheath 30, the support frame 210 can grow radially such that the tip is just smaller in diameter than the target vessel. For example, a large size of approximately 3-5 mm for clots in the ICA, an intermediate size for proximal/large M1 clots of approximately 0.090-0.110 inches in diameter, and/or a small size for small/distal M1 clots of approximately 0.080-0.090 inches in diameter. In many situations, the tip can have a maximum inner diameter 115 within a range of approximately 0.080-0.120 inches in the expanded deployed configuration. The support frame 210 further comprising a longitudinal length 211 sized to be less than three times the inner diameter 115 of the elongate body 110. The support frame 210 can include a collapsed length 221 in the collapsed delivery configuration and an expanded length 222 in the expanded deployed configuration, the collapsed length being greater than the expanded length.
Referring again to
The distal hoop segments 213 can fold distally in the collapsed configuration so that the distal hoop segments 213 are angled toward the distal end of the catheter 100. These folds in the support frame 210 can unfold when the catheter 100 is expended into the expanded configuration. In some examples, the plurality of distal hoop segments 213 can have distally unconnected peaks 228 which move distally when the support frame 210 is folded to the collapsed delivery configuration, as shown in
In certain examples, the support frame 210 can include one or more connecting spine(s) 216 from which the distal hoop segments 213 extend. In some examples, the connecting spine(s) 216 can be aligned with the axial spine 116 of the elongate body 110; in some examples, the connecting spine(s) 216 can be radially offset from the axial spine 116, as shown in
Alternately, a similar design can see a series of supporting ribs 118 merging into diametrically opposed spine connectors for connections with twin spines 116 spaced 180 degrees apart. Additional spines can also be envisioned which trade some lateral flexibility for better pushability than can be achieved with fewer spines. The additional axial stiffness can also help prevent the elongate body from stretching under tension, such as when an expandable tip is being drawn proximally into an outer sheath with a firm clot.
The catheter 100 can include a support ring 234 positioned between the elongate body 110 and the support frame 210. One end of the support ring 234 can be connected to the one or more axial spines 116 of the elongate body (e.g., after the distalmost rib 227), and the other end of the support ring 234 can be connected to the one or more connecting spines 223 of the support frame 210. The support ring 234 can add structural support of the junction between the elongate body 110 and the support frame 210. The support ring 234 can also provide an indication of the location of the support frame 210 within a target vessel, for example when viewing the target site under fluoroscopy. In some examples, the support ring 234 can include radiopaque markers 235 embedded therein or otherwise attached thereto. The radiopaque markers 235 can include a denser material than the remainder of the catheter 100 so as to alert the user of the location of the support frame 210. For example, the catheter 100 can comprise a flexible material such as Nitinol, whereas the radiopaque markers 235 can include high-density materials such as gold or platinum.
In some examples, the support frame 210 can include one or more floating spines 220. The floating spine(s) 220 can be positioned at, for example, 90 degrees around the circumference of the hoop segments 213, and can provide support to the hoop segments 213 as they unfold to the expanded deployed configuration. For example, the floating spine(s) 220 can ensure the hoop segments 213 unfold into a substantially circular shape. Unlike the connecting spine(s) 223, the floating spine(s) 220 can be disconnected from the support ring 234.
In some examples, the elongate body 110 can include a seam 148 between certain ribs 118 of the elongate body 110 and the axial spine 116. The seam 148 can help to disconnect the ribs 118 from the axial spine 116 a certain degree to enable radial expansion of the elongate body 110 and to provide a greater degree of flexibility to the body. The seam 148 can be created by forming the ribs 118 into a serpentine shape such that only every second, third, fourth, etc. rib 118 is attached to the axial spine 116 via spine connector 146.
The C-shaped petals 413 can be clocked at 90 degrees to each other for improved flexibility and enhanced ability to recover and maintain the shape and inner diameter of the support frame 410 when displaced laterally in a vessel. Additionally, a clocking offset between the connecting spine 416 of the support frame 410 and the axial spine 116 of the elongate body 110 can have a hinge effect allowing the structure to easily deflect away from vessel walls. As shown, the opposing C-shaped petals 413 can include distally unconnected peaks 428 at a distal end 414 of the support frame 410.
The jackets 180 can also be applied in a combination of other ways. Depending on their axial location on the elongate body 110 and/or support frames (e.g., support frame 210,310,410) the jacket 180 can be dip coated, sprayed, electro spun, and/or plasma deposited onto the support frame. In other examples, the jacket 180 can be a straight extrusion or extruded and post-formed onto the expanding tip and catheter body.
In order to allow for smooth delivery of the clot retrieval catheter 100 through an outer catheter, the outer surface of the jacket 180 can be coated with a low-friction or lubricious material, such as PTFE or commercially available lubricious coating.
The invention is not necessarily limited to the examples described, which can be varied in construction and detail. The terms “distal” and “proximal” are used throughout the preceding description and are meant to refer to a positions and directions relative to a treating physician. As such, “distal” or distally” refer to a position distant to or a direction away from the physician. Similarly, “proximal” or “proximally” refer to a position near or a direction towards the physician. Furthermore, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±20% of the recited value, e.g. “about 90%” may refer to the range of values from 71% to 99%.
In describing example embodiments, terminology has been resorted to for the sake of clarity. As a result, not all possible combinations have been listed, and such variants are often apparent to those of skill in the art and are intended to be within the scope of the claims which follow. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose without departing from the scope and spirit of the invention. It is also to be understood that the mention of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Similarly, some steps of a method can be performed in a different order than those described herein without departing from the scope of the disclosed technology.
The present application claims benefit of, and priority to, U.S. Provisional Patent Application No. 63/341,145 filed May 12, 2022. The entire contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63341145 | May 2022 | US |
