Patent Application
20090157163
This disclosure relates generally to medical devices and, more particularly, to retrieval devices having integrally formed wire baskets, and methods of manufacturing and using the same.
Extractors have been used for the removal of stones, calculi, and other foreign matter from within the body. One type of extractor has an end effector configured to form a basket at the distal end of a drive wire which extends into the body. The drive wire extends within a sheath and connects to an actuation handle located external to the body. The basket may be collapsed within the sheath to achieve a reduced diameter profile, and may be opened when it extends beyond the sheath. Once opened, a targeted stone may be captured within the basket. The captured stone, along with the extractor, may then be removed from the body. The baskets of such extractors may typically be formed by soldering, welding, or otherwise mechanically joining wires to form tips at distal and proximal ends of the basket. The drive wire may also be soldered, welded, or mechanically connected (mechanical joint) to the proximal end of the basket to couple the basket to the handle which actuates the basket.
In typical baskets, the mechanical joints that are used to form the tips may hinder access to the targeted stone and may increase the possibility of tissue damage within the body. In addition, the mechanical joints may also obstruct the sliding of the drive wire within the sheath during actuation. The size of the basket and the mechanical joint may also necessitate the use of a larger diameter sheath (to pass the drive wire through), increasing patient discomfort or hindering the ability of the device to be passed through a scope, such as a ureteroscope.
The present disclosure provides retrieval devices and methods of manufacturing and using the same that avoid some or all of the aforementioned shortcomings of existing devices.
In an exemplary embodiment of the present disclosure, a retrieval device is disclosed. The retrieval device may include a sheath including a lumen extending longitudinally through the sheath, an elongate member slidably disposed within the lumen, and a basket at a distal end of the elongate member. The basket may include a plurality of legs formed integrally with the elongate member. The elongate member and the basket may be formed of a single wire and the legs may be made by splitting a length of the single wire.
Various embodiments of the retrieval device may include one or more of the following aspects: a tip at a distal end of the plurality of legs, the tip may be formed integrally with the elongate member and the plurality of legs; the elongate member, the basket and the tip may be formed integrally without joints; the plurality of legs may be formed by one or more cuts extending all the way through a diameter of the elongate member; one cut may form two legs of the plurality of legs and two cuts may form four legs of the plurality of legs; the retrieval device may further include a handle at a proximal end of the elongate member, the handle may be configured to transition the basket from a retracted configuration to an expanded configuration; the retracted configuration may be a configuration where the basket is disposed within the lumen and the expanded configuration may be a configuration where the basket is disposed external to the lumen; the basket in the expanded configuration may form a closed cage with the plurality of legs having a bulbous shape; the basket in the expanded configuration may form an open cage with the plurality of legs forming prongs of a grasping device; the elongate region and the plurality of legs may be made of nitinol; and a diameter of the elongate region may be between about 8 mils and about 14 mils.
Another embodiment of the invention may include a method of manufacturing a medical device. The method may include splitting a length of wire at a distal end of the wire to form a plurality of legs separated by longitudinal slots, and shaping the plurality of legs to define a basket. The method may further include disposing the wire within a longitudinal lumen of a sheath such that the basket is proximate to a first end of the sheath.
Various embodiments of the method may include one or more of the following aspects: splitting the length of wire may include one of laser cutting, chemical etching, die cutting, Electronic Discharge Machining (EDM), and mechanically slicing; splitting a length of wire may include cutting all the way through a diameter of a section of the wire to form two legs of the plurality of legs; splitting a length of wire may further include rotating the wire and cutting the section of the wire all the way through the diameter to form four legs of the plurality of legs; the wire may be made of nitinol; the diameter of the wire may be between about 8 mils and about 14 mils; the length of wire may be separated from a distal-most end of the wire by a small section of the wire; shaping the plurality of legs may include curving the plurality of legs to form a closed basket having a bulbous shape; the length of wire may abut a distal-most end of the wire; shaping the plurality of legs may include curving the plurality of legs to form an open cage with the plurality of legs forming prongs of a grasping device; disposing the wire may include slidably disposing the wire such that the basket is configured to transition from a first configuration to a second configuration, the first configuration may be a configuration where the basket is disposed within the lumen and the second configuration may be a configuration where the basket is disposed external to the lumen.
Yet another embodiment of the invention may include a method of removing matter from the body of a patient. The method may include providing a medical device which includes a sheath defining a lumen, an elongate member slidably disposed within the lumen, and a basket having a plurality of legs. The elongate member and the basket may be made of a single wire, and the plurality of legs may be formed by splitting a length of the single wire at a distal end of the single wire. The method may also include advancing the medical device to a treatment site within the body of the patient, capturing the matter within the basket of the medical device, and removing the medical device from the body of the patient.
Various embodiments of the method may include one or more of the following aspects: the elongate member and the basket may be formed integrally without joints; capturing the matter may include transitioning the basket from a retracted configuration to an expanded configuration, the retracted configuration may be a configuration where the basket is disposed within the lumen and the expanded configuration may be a configuration where the basket is disposed external to the lumen; the length of the single wire may be separated from a distal-most end of the single wire by a small section of the single wire, and the basket may be configured to have a bulbous shape in the expanded configuration; the length of the single wire may abut a distal-most end of the single wire, and the basket may be configured to form an open cage with the plurality of legs forming prongs of a grasping device in the expanded configuration; the method may further include immobilizing the matter with the plurality of legs of the basket; the method may further include fragmenting the matter; the method may further include sweeping at least a portion of the matter from the treatment site with the plurality of legs of the basket; the matter may be one of a kidney stone, a struvite, an uric acid stone, a cystine stone, and a solid deposit; one cut may forms two legs of the plurality of legs; and two cuts may form four legs of the plurality of legs.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.
Exemplary embodiments of the present disclosure are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
The basket 16 may be attached to the member distal end 14. The basket 16 may be comprised of a plurality of legs 20. The plurality of legs 20 may include any number of legs (2, 3, 4, 5, etc.). The proximal end of these plurality of legs 20 may join together and be attached to the member distal end 14 and the distal end of the plurality of legs 20 may join together and be attached to the tip 18. In some embodiments, the tip 18 may possess an atraumatic configuration. In these embodiments, the tip 18 may possess any atraumatic configuration known in the art. For example, the tip 18 may be rounded, crimped, and/or capped.
The legs 20 may be attached to the elongate region 10 (at the member distal end 14) and the tip 18 in any conventional manner (such as, welding, soldering, gluing, crimping, or other mechanical connections). However, as will be described in connection with certain preferred embodiments, the legs 20 may be integrally formed with the elongate region 10 and/or the tip 18. That is, the legs 20 may be formed out of the same piece of material as the elongate region 10, such that the legs 20 and the elongate region 10 have a continuous material formation (for example, no welding, soldering, gluing, mechanical connections, etc. to connect two distinct parts together). In some embodiments, the tip 18 may also be integrally formed with the legs 20 and the elongate region 10. In these embodiments, the legs 20 may be created such that one end of the plurality of legs 20 is integral with the elongate region, and the other end is integral with the tip 18. In some other embodiments, only the legs 20 and the elongate region 10 may be integrally formed, while the legs 20 may be joined at the tip 18 in a conventional manner. It is also contemplated that, in some embodiments, the tip 18 may be eliminated and the legs 20 may extend all the way to the distal-most end of the inner member 11.
In the retracted configuration, illustrated in
The handle 50 of the device 100 may be configured to assist in transitioning the basket 16 between the retracted configuration (
In certain preferred embodiments of the invention, including those described herein, the inner member 11 may be a single solid wire integrally formed with the basket 16 and the tip 18, the wire having a relatively small and uniform diameter along its length. The inner member 11, however, may also be formed from a flexible rod, tube, hypotube, cannula, stent, or other piece of biocompatible material or combination of biocompatible materials known in the art. Such materials may include, but are not limited to, nylon, urethane, polyamide, PEBAX, stainless steel (such as 300 and 400 series including 316L, 304, 445), cobalt, chromium, nickel, titanium, nitinol, thermoforming plastic, polytetrafluoroethylene (“PTFE”), and expanded polytetrafluoroethylene (“ePTFE”). The inner member 11 may also be a metal coated with a polymer and may have one or more layers of material.
The elongate region 10 may be solid or hollow, and may be substantially cylindrical. In some embodiments, the diameter of the elongate region 10 may vary along the length. For instance, the diameter of the elongate region 10 may be greater near the member proximal end 12 than the member distal end 16. In these embodiments, the varying diameter of the elongate region 10 may make the inner member 11 stiffer near the handle 50 than near the basket 16. The varying stiffness of the inner member 11 may assist in sliding the inner member 11 in response to sliding of the thumb slide 8, and/or inserting the device 100 through tortuous anatomy of a patient. Alternatively, the elongate region 10 may have a substantially uniform cross-section along its length. In an exemplary embodiment, the elongate member 10 may be formed from a nitinol wire.
The overall length and diameter of the inner member 11 and/or the elongate region 10 may vary depending on the application. For example, a relatively long inner member 11 may be advantageous for retrieving stones 34 or other calculi deep within the body of the patient. In addition, an inner member 11 having a relatively small diameter may be advantageous for retrieving stones 34 from restricted passageways within the human urinary tract. The inner member 11 may be relatively flexible to facilitate the retrieval of stones 34 located in complex, tortuous body structures. In an exemplary embodiment, the diameter of the inner member 11 may be between about 0.008″ to 0.014″ (about 8 mils to about 14 mils, or about 200 microns to 360 microns).
The sheath 40, the handle 50, and the thumb slide 8 may be formed from any suitable materials used in the art. In some embodiments, the sheath 40, the handle 50, and the thumb slide 8 may be formed from a material discussed above with respect to the elongate region 10. Although
As described earlier, some preferred embodiments of the invention include a one-piece inner member 11 of integrally formed elongate region 10, basket 16, and tip 18. In such embodiments, no mechanical joints are used to attach the basket 16 to the elongate region 10 and/or the tip 18. Elimination of the mechanical joints reduces the overall cross-sectional size of the inner member 11, allowing a reduction in the diameter of the lumen 30. Reduction in the diameter of the lumen 30, in turn, reduces the cross-sectional size of the device 100, thereby reducing patient discomfort. Reduction in size of the device 100 also increases the capability of device 100 to traverse through restricted or tortuous body cavities. All other variables remaining the same, the flexibility (the inverse of flexural rigidity) of the device 100 is inversely proportional to the square of the device diameter. That is, a small decrease in device diameter may significantly increase the device flexibility. Increased flexibility of the device 100 increases the maneuverability of the device 100 within the body. A retrieval device made according to such embodiments can be in the range of approximately 1 Fr. in diameter.
Elimination of mechanical joints in the inner member 11 may also improve the ability of the inner member 11 to slide within the lumen 20 without the joint hindering such movement. Therefore, in embodiments of the invention with one-piece inner member 11, it may be easier to transition the basket 16 from retracted to an expanded configuration and vice versa.
Elimination of the joints may also reduce the possibility of device failure through breakage of a joint. Reduced possibility of inner member 11 breakage may increase the durability of the device 100. In addition, it may be safer to use a device 100 with a one-piece inner member 11 due to the reduced possibility of broken pieces of the inner member 11 being trapped within the body. Elimination of joints may also reduce the possibility of the joint scarring or tearing body tissue during operation.
Fabrication of an inner member 11 with a one piece inner member 11 may also be simpler and faster due to elimination of process steps. In addition to the elimination of one or more joining steps, the creation of a basket 16 on a one-piece inner member may be easier. For instance, for an inner member 11 made of a wire, a distal region can be split into two with one cutting operation to create two legs 20 of the basket 16. The inner member 11 may then be rotated and the two legs 20 split again in one cutting operation to create four legs 20. That is, a total of two cutting operations may create four legs 20. By contrast, for an inner member 11 made of, for example, a tube, two cutting operations may be required to separate one single leg.
In some embodiments of the current disclosure that achieve at least some of these advantages, the basket 16 may be formed by slicing a wire. The legs 20 of the basket 16 may be formed by slicing a length of material at the distal end of the inner member 11. Any process, such as laser cutting, chemical etching, electrical discharge machining (EDM), machine cutting, etc., capable of slicing a section of the inner member 11 may be used for the slicing operation.
The width of the longitudinal slot 22 may be controlled by controlling the width of the laser or by other means. As explained earlier, one longitudinal slot 22 may create two legs 20 of the basket 16. Multiple longitudinal slots 22 may be cut through the inner member 11 to create more legs 20. For instance, two longitudinal slots 22 ninety degrees (90°) apart may be cut through the entire diameter of the inner member 11 to form four symmetric legs 20. An even number of legs 20 may be formed in this manner. In embodiments, where an odd number of legs 20 are desired, one leg may be further laser cut to form two separate legs 20. A portion of the distal-most end of the inner member 11 may remain uncut to form the tip 18. In some embodiments, the tip 18 may be eliminated and the longitudinal slot 22 may extend to the distal-most end of the inner member 11. In such embodiments, the multiple legs 20 may be connected together only at the member distal end 14.
A secondary operation may now separate the legs 20 and increase the space between the legs 20 to form the basket 16.
The width and length L of the longitudinal slots 22, and the space between these slots 22 created during the secondary operation, may define the size and mechanical behavior of the basket legs 20. The desired width, length L, and spacing may vary depending on the particular application. For example, for some applications, relatively narrow basket legs 20 separated by large spaces may be desired to retrieve a relatively large stone 34. Each leg 20 may have the same length and width, or the length and width of each leg 20 may vary depending on the particular application. In addition, the width of the longitudinal slots 22 between the legs 20 may vary or be constant.
The shape of the legs 20 may be tailored to suit a particular application. For instance, as depicted in
The basket 16 may be subjected to additional processing steps to change the physical characteristics and mechanical behavior of the legs 20. For instance, the basket 16 may be heat treated to improve the elastic characteristics of the legs 20. The legs 20 may retain their shape and elasticity after repeated transitions between the expanded and retracted configuration. The shape of the basket 16 may be substantially formed when the basket 16 transitions from the retracted to the expanded configuration. The basket in the expanded configuration may possess a bulbous shape as depicted in
In some embodiments, cuts made through the inner member 11 may also form one or more relief features (not shown) at the ends of the longitudinal slots 22. These relief features may include widened ends of the longitudinal slots 22 and may assist in arresting crack propagation that may tend to fracture one or more legs 20. That is, the relief features may assist a longitudinal slot 22 in resisting tearing proximally and/or distally as a result of repeated opening and closing of the basket 16.
In some embodiments, the basket 16 may also include webbing, netting, or any other retrieval material (not shown) disposed between portions of at least two of the legs 20. The retrieval material may be, for example, polyvinylethylene (“PVE”), polyvinyl alcohol (“PVA”), ePTFE, PTFE, foam, rubber, plastic, polyurethane, or any other polymer or composite known in the art. The retrieval material may extend partially or completely along the length of the legs 20 between which it is disposed, and may act as a sieve between those legs 20. The retrieval material may allow, for example, fluid or other material to pass through, while preventing stones 34 from escaping the basket 16. The retrieval material may be attached to the legs 20 by welding, grafting, tying, or any other attachment method known in the art. The legs 20 of the basket 16 may also be coated with a sheet of protection material (not shown) to protect the legs 20 during processes such as, for example, laser lithotripsy.
The configurations, materials, and other characteristics of the basket 16 described herein permit the basket 16 to assume a retracted configuration within the sheath 40 for delivery to a treatment site, and an expanded configuration for use at the treatment site. At least some aspects of the present disclosure may be used, for example, to retrieve a stone 34, calculus, or other material from any location within the body, such as, for example, in the urinary tract of the patient. An exemplary application of the disclosed retrieval device 100 will now be described.
The device 100 may be inserted through the urethra of the patient or, alternatively, the device 100 may be inserted percutaneously to a treatment site. The treatment site within the body may correspond to the location of a targeted stone 34. The stone 34 targeted for retrieval may be a kidney stone, a struvite, an uric acid stone, a cystine stone, or other solid deposit commonly removed from a body structure or passageway within the body. Such stones 34 may contain various combinations of chemicals, including, but not limited to, calcium, oxalate, and phosphate. The stone 34 may be of any size and could have a length or diameter of approximately 1 mm to 12 mm. These lengths and diameters are merely exemplary, and aspects of the present disclosure may assist in the retrieval of stones larger or smaller than those discussed herein. Stones 34 may be of any shape and could be, for example, flat, round, smooth, or jagged. The device 100 may retrieve stones 34 that are both impacted and free floating.
The device 100 may be advanced to the treatment site through an access sheath (not shown), stent, or other access or dilatation device known in the art. In addition, the device 100 may be used in conjunction with an endoscope (not shown) or other type of intracorporeal scope known in the art. The endoscope may advance through the body to the treatment site. Once the treatment site has been reached, the device 100 may be fed through an access port of the endoscope to gain access to the stone 34.
While being advanced to the treatment site, the basket 16 of the device 100 may be in the retracted configuration within the sheath 40. The retracted configuration (shown in
If, however, the targeted stone 34 is too large (in some embodiments, larger than approximately 3 mm) to be safely removed from the body, the user may first reduce the size of the stone 34 prior to removal. In this case, the device 100 may be used to capture the stone 34 as described earlier. The user may then perform a stone-reduction process, such as, for example, laser lithotripsy, to break up or otherwise reduce the size of the stone 34. The device 100 may act as a backstop during such a process and may assist in preventing particles of the stone 34 from migrating or escaping from the treatment site during (or after) the stone-reduction process. In such a process, a laser fiber (not shown) or other conventional device may be used to break up the stone 34. The laser fiber may be delivered to the stone 34 through an access port of the endoscope (or a lumen of the sheath 40) and used to fragment (reduce the size of) the stone 34. Once the stone 34 has been fragmented, the basket 16 may be swept across the area to sweep the stone fragments into the basket 16. The captured stone fragments may then be extracted from the body.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. For example, the inner member 11 and/or the sheath 40 may include a plurality of flexibility features configured to increase the flexibility of the device 100. The flexibility features may be formed by removing a portion of the inner member 11 and/or the sheath 40. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.
This application is based upon and claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/006,053 to Cheng et al. filed on Dec. 17, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 61006053 | Dec 2007 | US |
