Patent Application
20120265186
In one embodiment of the invention, disclosed is a steerable, curvable energy delivery catheter that can be used in a wide variety of applications including vertebroplasty and kyphoplasty. The catheter can include an elongate, tubular body, having a proximal end, a distal end, and a central lumen extending therethrough; a deflectable zone on the distal end of the tubular body, deflectable through an angular range; a handle on the proximal end of the tubular body; and a deflection control on the handle. The catheter can also include one or two or more energy delivery elements that can be, for example, in the vicinity of the deflectable zone of the device. In some embodiments, the energy delivery elements can be bipolar or monopolar RF electrodes in some embodiments, or as otherwise described in the application. For example, in other embodiments, the energy delivery elements could alternatively or additionally include a cryoprobe. The energy delivery elements can be connected via fiber optics, conductive wires, one or more lumens, other modalities, or wirelessly to an energy source. The energy source can be an RF generator in some embodiments. In other embodiments, the energy source can include a cryogenic source.
In another embodiment, a steerable and curvable ablation catheter is provided. The catheter comprises an elongate tubular body having a proximal end and a distal end, wherein the distal end includes a deflectable zone deflectable through an angular range; a handle on the proximal end of the tubular body; a deflection control on the handle; and an ablation element configured to ablate tissue carried by the deflectable zone. The ablation element can comprise a radiofrequency (RF) electrode or cryoprobe. The steerable and curvable ablation catheter can also comprise an actuator extending axially between the deflection control and the deflectable zone, wherein the actuator comprises and axially moveable element. The deflectable zone can be in a substantially straight configuration from the proximal end to the distal end in an unstressed state. The steerable and curvable catheter can include more than one ablation element.
In another embodiment, a method of ablating tissue is provided. The method comprises positioning a catheter near a zone of tissue to be ablated, the catheter having an elongate body having a proximal end, a deflection control carried by the proximal end, a deflectable distal end, and an ablation element carried by the deflectable distal end; deflecting at least a portion of the distal end of the elongate body through an angular range; and contracting the tissue with the ablation element to ablate the tissue. The ablation element can be an RF heating electrode or a cryoprobe. The tissue to be ablated can comprise cortical bone, cancellous bone, a vertebral body, or a tumor. The ablation can occur as part of a vertebroplasty procedure.
The present invention provides improved delivery systems for delivery of a bone cement or bone cement composite for the treatment of vertebral compression fractures due to osteoporosis (OSP), osteo-trauma, and benign or malignant lesions such as metastatic cancers and myeloma, and associated access and deployment tools and procedures.
The primary materials in the preferred bone cement composite are methyl methacrylate and inorganic cancellous and/or cortical bone chips or particles. Suitable inorganic bone chips or particles are sold by Allosource, Osteotech and LifeNet (K053098); all have been cleared for marketing by FDA. The preferred bone cement also may contain the additives: barium sulfate for radio-opacity, benzoyl peroxide as an initiator, N,N-dimethyl-p-toluidine as a promoter and hydroquinone as a stabilizer. Other details of bone cements and systems are disclosed in U.S. patent application Ser. No. 11/626,336, filed Jan. 23, 2007, the disclosure of which is hereby incorporated in its entirety herein by reference.
One preferred bone cement implant procedure involves a two-step injection process with two different concentrations of the bone particle impregnated cement. To facilitate the implant procedure the bone cement materials are packaged in separate cartridges containing specific bone cement and inorganic bone particle concentrations for each step. Tables 1 and 2, infra, list one example of the respective contents and concentrations in Cartridges 1A and 1B for the first injection step, and Cartridges 2A and 2B for the second injection step.
The bone cement delivery system generally includes at least three main components: 1) stylet; 2) introducer cannula; and 3) steerable injection needle. See
The stylet is used to perforate a hole into the pedicle of the vertebra to gain access to the interior of the vertebral body.
The introducer cannula is used for bone access and as a guide for the steerable injection needle. The introducer cannula is sized to allow physicians to perform vertebroplasty or kyphoplasty on vertebrae with small pedicles such as the thoracic vertebra T5 as well as larger vertebrae. In addition, this system is designed for uni-transpedicular access and/or bi-pedicular access.
Once bone access has been achieved, the steerable injection needle can be inserted through the introducer cannula into the vertebra. The entire interior vertebral body may be accessed using the steerable injection needle. The distal end of the needle can be manually shaped to any desired radius within the product specifications. The radius is adjusted by means of a knob on the proximal end of the device.
The hand-held cement dispensing pump may be attached to the steerable injection needle by a slip-ring luer fitting. The pre-filled 2-chambered cartridges (1A and 1B, and 2A and 2B) are loaded into the dispensing pump. As the handle of the dispensing pump is squeezed, each piston pushes the cartridge material into the spiral mixing tube. The materials are mixed in the spiral mixing nozzle prior to entering the steerable injection needle. The ratio of diameters of the cartridge chambers determines the mixing ratio for achieving the desired viscosity.
The bone cement implant procedures described herein use established vertebroplasty and kyphoplasty surgical procedures to stabilize the collapsed vertebra by injecting bone cement into cancellous bone.
The preferred procedure is designed for uni-transpedicular access and may be accomplished under either a local anesthetic or short-duration general anesthetic. Once the area of the spine is anesthetized, an incision is made and the stylet is used to perforate the vertebral pedicle and gain access to the interior of the vertebral body. The introducer cannula is then inserted and acts as a guide for the steerable injection needle.
Injection of the preferred bone cement involves a two-step procedure. The pre-filled Cartridges 1A and 1B are loaded into the dispensing pump. As the dispensing pump handle is squeezed, each piston pushes material into the spiral mixing tube. The diameter of each chamber may be utilized to determine the mixing ratio for achieving the desired viscosity.
The first step involves injecting a small quantity of PMMA with more than about 35%, e.g., 60% inorganic bone particles, onto the outer periphery of the cancellous bone matrix, i.e., next to the inner wall of the cortical bone of the vertebral body. The cement composite is designed to harden relatively quickly, forming a firm but still pliable shell. This shell is intended to prevent bone marrow/PMMA content from being ejected through any venules or micro-fractures in the vertebral body wall. The second step of the procedure involves a second injection of PMMA with an approximately 30% inorganic bone particles to stabilize the remainder of the weakened, compressed cancellous bone.
Alternatively, the steerable needle disclosed herein and discussed in greater detail below, can be used in conventional vertebroplasty procedures, using a single step bone cement injection.
Injection control for the first and second steps is provided by a 2 mm ID flexible injection needle, which is coupled to the hand operated bone cement injection pump. The 60% (>35%) and 30% ratio of inorganic bone particle to PMMA concentrations may be controlled by the pre-filled cartridge sets 1A and 1B, and 2A and 2B. At all times, the amount of the injectate is under the direct control of the surgeon or intervention radiologist and visualized by fluoroscopy. The introducer cannula is slowly withdrawn from the cancellous space as the second injection of bone cement begins to harden, thus preventing bone marrow/PMMA content from exiting the vertebral body. The procedure concludes with closure of the surgical incision with bone filler. In vitro and in vivo studies have shown that the 60% (>35%) bone-particle impregnated bone cement hardens in 2-3 minutes and 30% bone-particle impregnated bone cement hardens between 4 to 10 minutes.
Details of the system components will be discussed below.
There is provided in accordance with the present invention a steerable injection device that can be used to introduce any of a variety of materials or devices for diagnostic or therapeutic purposes. In one embodiment, the system is used to inject bone cement, e.g., PMMA or any of the bone cement compositions disclosed elsewhere herein. The injection system most preferably includes a tubular body with a steerable (i.e., deflectable) distal portion for introducing bone cement into various locations displaced laterally from the longitudinal axis of the device within a vertebral body during a vertebroplasty procedure.
Referring to
The manifold 18 is additionally provided with a control 26 such as a rotatable knob, slider, or other moveable control, for controllably deflecting a deflection zone 24 on the distal end 16 of the tubular body 12. As is described elsewhere herein, the deflection zone 24 may be advanced from a relatively linear configuration as illustrated in
Referring to
The central lumen 38 has an inside diameter which is adapted to slideably axially receive the steerable injection needle 10 therethrough. This enables placement of the distal end 34 adjacent a treatment site within the body, to establish an access pathway from outside of the body to the treatment site. As will be appreciated by those of skill in the art, the introducer 30 enables procedures deep within the body such as within the spine, through a minimally invasive and/or percutaneous access. The steerable injection needle 10 and/or other procedure tools may be introduced into port 40, through lumen 38 and out of port 42 to reach the treatment site.
The proximal end 32 of introducer 30 may be provided with a handle 44 for manipulation during the procedure. Handle 44 may be configured in any of a variety of ways, such as having a frame 46 with at least a first aperture 48 and a second aperture 50 to facilitate grasping by the clinician.
Referring to
As will be appreciated by those of skill in the art, the stylet 60 has an outside diameter which is adapted to coaxially slide within the central lumen on introducer 30. When block 68 is nested within recess 70, a distal end 64 of stylet 60 is exposed beyond the distal end 34 of introducer 30. The distal end 64 of stylet 60 may be provided with a pointed tip 72, such as for anchoring into the surface of a bone.
Referring to
The shaft 702 defines at least one lumen therethrough that is preferably configured to carry a flowable bone cement prior to hardening. Proximal portion 710 of shaft 702 is preferably relatively rigid, having sufficient column strength to push through cancellous bone. Distal portion 712 of shaft 702 is preferably flexible and/or deflectable and reversibly actuatable between a relatively straight configuration and one or more deflected configurations or curved configurations as illustrated, for example, in
Input port 704 may be provided with a Luer lock connector although a wide variety of other connector configurations, e.g., hose barb or slip fit connectors can also be used. Lumen 705 of input port 704 is fluidly connected to central lumen 720 of shaft 702 such that material can flow from a source, through input port 704 into central lumen 720 of the shaft 702 and out the open distal end or out of a side opening on distal portion 712. Input port 704 is preferably at least about 20 gauge and may be at least about 18, 16, 14, or 12 gauge or larger in diameter.
Input port 704 advantageously allows for releasable connection of the steerable injection device 700 to a source of hardenable media, such as a bone cement mixing device described herein. In some embodiments, a plurality of input ports 704, such as 2, 3, 4, or more ports are present, for example, for irrigation, aspiration, introduction of medication, hardenable media precursors, hardenable media components, catalysts or as a port for other tools, such as a light source, cautery, cutting tool, visualization devices, or the like. A first and second input port may be provided, for simultaneous introduction of first and second bone cement components such as from a dual chamber syringe or other dispenser. A mixing chamber may be provided within the injection device 700, such as within the proximal handle, or within the tubular shaft 702
A variety of adjustment controls 706 may be used with the steerable injection system, for actuating the curvature of the distal portion 712 of the shaft 702. Preferably, the adjustment control 706 advantageously allows for one-handed operation by a physician. In one embodiment, the adjustment control 706 is a rotatable member, such as a thumb wheel or dial. The dial can be operably connected to a proximal end of an axially movable actuator such as pull wire 724. See
In some embodiments, the adjustment control 706 allows for continuous adjustment of the curvature of the distal portion 712 of shaft 702 throughout a working range. In other embodiments, the adjustment control is configured for discontinuous (i.e., stepwise) adjustment, e.g., via a ratcheting mechanism, preset slots, deflecting stops, a rack and pinion system with stops, ratcheting band (adjustable zip-tie), adjustable cam, or a rotating dial of spring loaded stops. In still other embodiments, the adjustment control 706 may include an automated mechanism, such as a motor or hydraulic system to facilitate adjustment.
The adjustment control may be configured to allow deflection of the distal portion 712 through a range of angular deviations from 0 degrees (i.e., linear) to at least about 15°, and often at least about 25°, 35°, 60°, 90°, 120°, 150°, or more degrees from linear.
In some embodiments, the length X of the flexible distal portion 712 of shaft 702 is at least about 10%, in some embodiments at least about 15%, 25%, 35%, 45%, or more of the length Y of the entire shaft 702 for optimal delivery of bone cement into a vertebral body. One of ordinary skill in the art will recognize that the ratio of lengths X:Y can vary depending on desired clinical application. In some embodiments, the maximum working length of needle 702 is no more than about 15″, 10″, 8″, 7″, 6″, or less depending upon the target and access pathway. In one embodiment, when the working length of needle 702 is no more than about 8″, the adjustable distal portion 712 of shaft has a length of at least about 1″ and preferably at least about 1.5″ or 2″.
In some embodiments, the slots 718 can be machined or laser cut out of the tube stock that becomes shaft 702, and each slot may have a linear, chevron or other shape. In other embodiments, the distal portion 712 of shaft 702 may be created from an elongate coil rather than a continuous tube.
Slots 718 provide small compression hinge joints to assist in the reversible deflection of distal portion 712 of shaft 702 between a relatively straightened configuration and one or more curved configurations. One of ordinary skill in the art will appreciate that adjusting the size, shape, and/or spacing of the slots 718 can impart various constraints on the radius of curvature and/or limits of deflection for a selected portion of the distal portion 712 of shaft 702. For example, the distal portion 712 of shaft 702 may be configured to assume a second, fully deflected shape with a relatively constant radius of curvature throughout its length. In other embodiments, the distal portion 712 may assume a progressive curve shape with a variable radius of curvature which may, for example, have a decreasing radius distally. In some embodiments, the distal portion may be laterally displaced through an arc having a radius of at least about 0.5″, 0.75″, 1.0″, 1.25″, or 1.5″ minimum radius (fully deflected) to ∞ (straight) to optimize delivery of bone cement within a vertebral body. Wall patterns and deflection systems for bendable slotted tubes are disclosed, for example, in U.S. Patent Publication No. 2005/0060030 A1 to Lashinski et al., the disclosure of which is incorporated in its entirety by reference herein.
Still referring to
A distal opening 728 is provided on shaft 702 in communication with central lumen 720 to permit expression of material, such as bone cement, from the injector 700. Some embodiments may include a filter such as mesh 812. Mesh structure 812 can advantageously control cement output by controlling bubbles and/or preventing undesired large or unwieldy aggregations of bone cement from being released at one location and thus promote a more even distribution of bone cement within the vertebral body. The mesh 812 may be created by a laser-cut cris-crossing pattern within distal end as shown, or can alternatively be separately formed and adhered, welded, or soldered on to the distal opening 728. Referring to
In some embodiments, the distal shaft 712 can generate a lateral force of at least about 0.125 pounds, 0.25 pounds, 0.5 pounds, 1 pound, 1.5 pounds, 2 pounds, 3 pounds, 4 pounds, 5 pounds, 6 pounds, 7 pounds, 8 pounds, 9 pounds, 10 pounds, or more by activating control 706. This can be advantageous to ensure that the distal portion 712 is sufficiently navigable laterally through cancellous bone to distribute cement to the desired locations. In some embodiments, the distal shaft 712 can generate a lateral force of at least about 0.125 pounds but no more than about 10 pounds; at least about 0.25 pounds but no more than about 7 pounds; or at least about 0.5 pounds but no more than about 5 pounds.
In some embodiments, the distal portion 712 of shaft 702 (or end cap 730) has visible indicia, such as, for example, a marker visible via one or more imaging techniques such as fluoroscopy, ultrasound, CT, or MRI.
The distal curved portion 734 may be configured to be axially movably received within an outer tubular sheath 738. The sheath 738 is preferably configured to have sufficient rigidity and radial strength to maintain the curved distal portion 734 of shaft 732 in a relatively straightened configuration while the outer tubular sheath 738 coaxially covers the curved distal portion 734. Sheath 738 can be made of, for example, a metal such as stainless steel or various polymers known in the catheter arts. Axial proximal withdrawal of the sheath 738 with respect to tubular shaft 736 will expose an unconstrained portion of the shape memory distal end 734 which will revert to its unstressed arcuate configuration. Retraction of the sheath 738 may be accomplished by manual retraction by an operator at the proximal end, retraction of a pull wire attached to a distal portion of the sheath 738, or other ways as known in the art. The straightening function of the outer sheath 738 may alternatively be accomplished using an internal stiffening wire, which is axially movably positionable within a lumen extending through the tubular shaft 736. The length, specific curvature, and other details of the distal end may be as described elsewhere herein.
In another embodiment, as shown in
Introducer 800 includes a needle-redirecting element 804 such as an inclined surface near its distal end. Needle-redirecting element 804 can be, for example, a laser-cut tang or a plug having a proximal surface configured such that when needle 802 is advanced distally into introducer 800 and comes in contact with the needle-redirecting element 804, a distal portion 814 of needle 802 is redirected out an exit port 806 of introducer 800 at an angle 808, while proximal portion 816 of needle 802 remains in a relatively straightened configuration, as shown in
The illustrated embodiment of
The interior sleeve 709 is preferably in the form of a continuous, tubular flexible material, such as nylon or polyethylene. In an embodiment in which the needle 702 has an outside diameter of 0.095 inches (0.093 inch coil with a 0.001 inch thick outer sleeve) and an inside diameter of 0.077 inches, the interior tubular sleeve 709 may have an exterior diameter in the area of about 0.074 inches and an interior diameter in the area of about 0.069 inches. The use of this thin walled tube 705 on the inside of the needle shaft 702 is particularly useful for guiding a fiber through the needle shaft 702. The interior tube 705 described above is additionally preferably fluid-tight, and can be used to either protect the implements transmitted therethrough from moisture, or can be used to transmit bone cement through the steerable needle.
In some embodiments, an outer tubular coating or sleeve (not shown) is provided for surrounding the steerable needle shaft at least partially throughout the distal end of the needle. The outer tubular sleeve may be provided in accordance with techniques known in the art and, in one embodiment, is a thin wall polyester (e.g., ABS) heat shrink tubing such as that available from Advanced Polymers, Inc. in Salem, N.H. Such heat shrink tubings have a wall thickness of as little as about 0.0002 inches and tube diameter as little as about 0.010 inches. The outer tubular sleeve enhances the structural integrity of the needle, and also provides a fluid seal and improved lubricity at the distal end over embodiments with distal joints 718. Furthermore, the outer tubular sleeve tends to prevent the device from collapsing under a proximal force on a pull wire. The sleeve also improves pushability of the tubular members, and improves torque transmission.
In other embodiments, instead of a slotted tube, the needle shaft of a vertebroplasty injection system may include a metal or polymeric coil. Steerable helical coil-type devices are described, for example, in U.S. Pat. No. 5,378,234 or 5,480,382 to Hammerslag et al., which are both incorporated by reference herein in their entirety.
An interior tubular sleeve (not illustrated) may be provided to facilitate flow of media through the central lumen as described elsewhere in the application. In some embodiments, a heat-shrink outer tubular sleeve as described elsewhere in the application is also provided to enhance the structural integrity of the sheath, provide a fluid seal across the chevrons or slots, as well as improve lubricity.
The steerable injection needle (also referred to as the injection shaft) may have an outside diameter of between about 8 to 24 gauge, more preferably between about 10 to 18 gauge, e.g., 12 gauge, 13 gauge (0.095″ or 2.41 mm), 14 gauge, 15 gauge, or 16 gauge. In some embodiments, the inside diameter (luminal diameter) of the injection needle is between about 9 to 26 gauge, more preferably between about 11 to 19 gauge, e.g., 13 gauge, 14 gauge, 15 gauge, 16 gauge, or 17 gauge. In some embodiments, the inside diameter of the injection needle is no more than about 4 gauge, 3 gauge, 2 gauge, or 1 gauge smaller than the outside diameter of the injection needle.
The inside luminal diameter of all of the embodiments disclosed herein is preferably optimized to allow a minimal exterior delivery profile while maximizing the amount of bone cement that can be carried by the needle. In one embodiment, the outside diameter of the injection needle is 13 gauge (0.095″ or 2.41 mm) with a 0.077″ (1.96 mm) lumen. In some embodiments, the percentage of the inside diameter with respect to the outside diameter of the injection needle is at least about 60%, 65%, 70%, 75%, 80%, 85%, or more.
Referring to
Input port 704 is in fluid communication with a distal opening 728 on a distal tip 730, by way of an elongate central lumen 720. Input port 704 may be provided with any of a variety of releasable connectors, such as a luer or other threaded or mechanically interlocking connector known in the art. Bone cement or other media advanced through lumen 720 under pressure may be prevented from escaping through the plurality of slots 718 in the steering region 24 by the provision of a thin flexible tubular membrane carried either by the outside of tubular shaft 702, or on the interior surface defining central lumen 720.
Referring to
Slider 734 is provided with at least one axially extending keyway or spline 742 for slideably engaging a slide dowel pin 744 linked to the handle 708. This allows rotation of the rotatable control 706, yet prevents rotation of the slider 734 while permitting axial reciprocal movement of the slider 734 as will be apparent to those of skill in the art. One or more actuating knob dowel pins 746 permits rotation of the rotatable control 706 with respect to the handle 708 but prevents axial movement of the rotatable control 706 with respect to the handle 708.
Referring to
In general, the distal tip 730 includes a proximal opening 750 for receiving media from the central lumen 720, and advancing media through distal opening 728. Distal opening 728 may be provided on a distally facing surface, on a laterally facing surface, or on an inclined surface of the distal tip 730.
Referring to
Referring to
In the illustrated embodiment, the inclined aperture 728 is defined by an aperture plane 772 intersecting the longitudinal axis 770 at an angle θ which is at least about 5°, often at least about 15°, and in many embodiments, at least about 25° or more. Intersection angles within the range of from about 15° to about 45° may often be used, depending upon the desired clinical performance.
Referring to
Referring to
Referring to
In use, the distal tip 730 may be distally advanced through soft tissue, cortical or cancellous bone, with the distal opening 728 being maintained in a closed orientation. Following appropriate positioning of the distal tip 30, the introduction of bone cement or other media under pressure through the central lumen 720 forces the distal opening 728 open by radially outwardly inclining each leaflet 758 about its flection point 762. This configuration enables introduction of the needle without “coring” or occluding with bone or other tissue, while still permitting injection of bone cement or other media in a distal direction.
Any of the forgoing or other tip configurations may be separately formed and secured to the distal end of the tubular body 702, or may be machined, molded or otherwise formed integrally with the tube 702.
Alternatively, a distal opening aperture may be occluded by a blunt plug or cap, which prevents coring during distal advance of the device. Once positioned as desired, the distal cap may be pushed off of the distal end of the injector such as under the pressure of injected bone cement. The deployable cap may take any of a variety of forms depending upon the injector design. For example, it may be configured as illustrated in
As a further alternative, coring during insertion of an injector having a distal opening may be prevented by positioning a removable obturator in the distal opening. The obturator comprises an elongate body, extending from a proximal end throughout the length of the injector to a blunt distal tip. The obturator is advanced axially in a distal direction through the central lumen, until the distal tip of the obturator extends slightly distally of the distal opening in the injector. This provides a blunt atraumatic tip for distal advance of the injector through tissue. Following positioning of the injector, the obturator may be proximally withdrawn from the central lumen, and discarded. The obturator may be provided with any of a variety of structures for securing the obturator within the central lumen during the insertion step, such as a proximal cap for threadably engaging a complementary luer connector on the proximal opening of the central lumen.
In accordance with another aspect of the present invention, there is provided a combination device in which a steerable injector is additionally provided with a cavity formation element. Thus, the single device may be advanced into a treatment site within a bone, expanded to form a cavity, and used to infuse bone cement or other media into the cavity. Either or both of the expansion step and the infusion step may be accomplished following or with deflection of the distal portion of the injector.
Referring to
The slots 308 oppose a column strength element such as an axially extending spine 310, for resisting axial elongation or compression of the device. A pull wire 312 axially moveably extends throughout the length of the tubular body, and is secured with respect to the tubular body distally of the transverse slots 308. The proximal end of the pull wire is operatively connected to a control on a proximal handpiece or manifold. The control may be any of a variety of structures, such as a lever, trigger, slider switch or rotatable thumb wheel or control knob. Axial proximal traction (or distal advance) of the pull wire 312 with respect to the tubular body causes a lateral deflection of the distal steering section 306, by axial compression or expansion of the transverse slots 308 relative to the spine 310.
A distal aperture 314 is in communication via a central lumen 316 with the proximal end of the steerable injector 300. Any of a variety of tip configurations may be used such as those disclosed elsewhere herein. The proximal end of the central lumen 316 may be provided with a luer connector, or other connection port to enable connection to a source of media such as bone cement to be infused. In the illustrated embodiment, the aperture 314 faces distally from the steerable injector 302, although other exit angles may be used as will be discussed below.
The steerable injector 300 is optionally provided with a cavity forming element 320, such as an inflatable balloon 322. In the illustrated embodiment, the inflatable balloon 322 is positioned in the vicinity of the steerable distal section 306. Preferably, the axial length of a distal leading segment 307 is minimized, so that the balloon 322 is relatively close to the distal end of the steerable injector 300. In this embodiment, the plurality of transverse slots 308 are preferably occluded, to prevent inflation media from escaping into the central lumen 316 or bone cement or other injectable media from escaping into the balloon 322. Occlusion of the transverse slots 308 may be accomplished in any of variety of ways: i) by positioning a thin tubular membrane coaxially about the exterior surface of the tubular body, and ii) heat shrinking or otherwise securing the membrane across the openings. Any of a variety of heat shrinkable polymeric sleeves, comprising high density polyethylene or other materials, is well known in the catheter arts. Alternatively, a tubular liner may be provided within the central lumen 316, to isolate the central lumen from the transverse slots 308.
The balloon 322 is secured at a distal neck 309 to the leading segment 307 as is understood in the balloon catheter arts. The distal neck 309 may extend distally from the balloon, as illustrated, or may invert and extend proximally along the tubular body. In either event, the distal neck 309 of the balloon 322 is preferably provided with an annular seal 324 either directly to the tubular body 301 or to a polymeric liner positioned concentrically about the tubular body, depending upon the particular device design. This will provide an isolated chamber within balloon 322, which is in fluid communication with a proximal source of inflation media by way of an inflation lumen 326.
In the illustrated embodiment, the balloon 322 is provided with an elongate tubular proximal neck which extends throughout the length of the steerable injector 300, to a proximal port or other site for connection to a source of inflation media. This part can be blow molded within a capture tube as is well understood in the balloon catheter arts, to produce a one piece configuration. Alternatively, the balloon can be separately formed and bonded to a tubular sleeve. During assembly, the proximal neck or outer sleeve 328 may conveniently be proximally slipped over the tubular body 301, and secured thereto, as will be appreciated by those of skill in the catheter manufacturing arts.
Referring to
In some embodiments, the cavity-creating element could include a reinforcing layer that may be, for example, woven, wrapped or braided (collectively a “filament” layer), for example, over the liner of a balloon. The filament layer can advantageously protect the balloon from damage while in the working space, for example from jagged cancellous bone fragments within the interior of the vertebral body. The filament layer can also significantly elevated the burst pressure of the balloon, such that it exceeds about 20 ATM, in some embodiments exceeds about 25 ATM, and in a preferred embodiment, is at least about 30 ATM.
The filament layer can also be configured to control the compliance of the balloon depending on the desired clinical result, either symmetrically or, if the filaments are asymmetric, to constrain expansion of the balloon in one or more directions. In some embodiments, the balloon can be said to have a first compliance value when inflated to a first volume at a given first pressure when the balloon expands without being mechanically constrained by the constraining element such as the filament layer. The balloon can have a second compliance value when further inflated to a second volume (greater than the first volume) at a given second pressure (greater than the first pressure) when the balloon expands while being mechanically constrained by the constraining element. The second compliance value is, in some embodiments, less than the first compliance value due to the effect of the constraining element on the balloon. The second compliance value can be, for example, at least about 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, or 70% less than the first compliance value. In other embodiments, the second compliance value can be, for example, no more than about 70%, 60%, 50%, 40%, 30%, 25%, 20%, 15%, 10%, or 5% less than the first compliance value. In embodiments with a plurality of braided layers, the balloon could have an additional third, fourth, etc. progressively lower compliance values.
The filament 340 may comprise any of a variety of metallic ribbons, although wire-based braids could also be used. In some embodiments, the ribbons can be made at least in part of wires in braids or made of strips of a shape memory material such as Nitinol or Elgiloy, or alternatively stainless steel, such as AISI 303, 308, 310, and 311. When using a braid 340 containing some amount of a super-elastic alloy, an additional step may be desirable in some embodiments to preserve the shape of the stiffening braid 340. For instance, with a Cr-containing Ni/Ti superelastic alloy which has been rolled into 1 mm×4 mm ribbons and formed into a 16-member braid 340, some heat treatment is desirable. The braid 340 may be placed onto a, e.g., metallic, mandrel of an appropriate size and then heated to a temperature of 600 degrees Fahrenheit to 750 degrees Fahrenheit for a few minutes, to set the appropriate shape. After the heat treatment step is completed, the braid 340 retains its shape and the alloy retains its super-elastic properties.
In some embodiments, metallic ribbons can be any of a variety of dimensions, including between about 0.25 mm and 3.5 mm in thickness and 1.0 mm and 5.0 mm in width. Ribbons can include elongated cross-sections such as a rectangle, oval, or semi-oval. When used as ribbons, these cross-sections could have an aspect ratio of thickness-width of at least 0.5 in some embodiments.
In some embodiments, the braid 340 may include a minor amount of fibrous materials, both synthetic and natural, may also be used. In certain applications, particularly in smaller diameter catheter sections, more malleable metals and alloys, e.g., bold, platinum, palladium, rhodium, etc., can be used. A platinum alloy with a few percent of tungsten is sometimes could be used partially because of its radio-opacity.
Nonmetallic ribbons or wires can also be used, including, for example, materials such as those made of polyaramides (Kevlar), polyethylene terephthalate (Dacron), polyamids (nylons), polyimide carbon fibers, or a shape memory polymer.
In some embodiments, the braids 340 can be made using commercial tubular braiders. The term “braid” when used herein includes tubular constructions in which the wires or ribbons making up the construction are woven in an in-and-out fashion as they cross, so as to form a tubular member defining a single lumen. The braid members may be woven in such a fashion that 2-4 braid members are woven together in a single weaving path, although single-strand weaving paths can also be used. In some embodiments, the braid 340 has a nominal pitch angle of 45 degrees. Other braid angles, e.g., from 20 degrees to 60 degrees could also be used.
In some embodiments, the cavity creation element includes two or more coaxial balloons, including an inner balloon 322 and an outer balloon 370 as illustrated schematically in
In some embodiments, the cavity creation element could be asymmetrical, for example, as with the balloon 344 offset from the longitudinal axis of the tubular body 301 illustrated schematically in
Referring to
As a further alternative, the distal aperture or apertures 314 may be provided in any of a variety of configurations on a distal cap or tip, adapted to be secured to the tubular body.
In some embodiments, it may be advantageous to have multiple cavity-creation elements on a steerable injector in order to, for example, more quickly and efficiently move sclerotic cancellous bone to better facilitate cavity formation and the subsequent introduction of cement media. Referring to
In some embodiments, the first balloon 330 and the second balloon 332 share a common inflation lumen 326 (such as illustrated in
The first balloon 330 and the second balloon 332 can have substantially the same properties or differing properties, such as thickness, material, inflation diameter, burst strength, compliance, or symmetry (or lack thereof) depending on the desired clinical result. In some embodiments, the distal aperture 314 could be distally facing, positioned on a side wall, or on an inclined surface; or 2, 3, 4, 5, or more apertures could be presented as previously described. Furthermore, while the aperture 314 is illustrated in
The steerable injection systems described above are preferably used in conjunction with a mixing and dispensing pump for use with a multi-component cement. In some embodiments, a cement dispensing pump is a hand-held device having an interface such as a tray or chamber for receiving one or more cartridges. In one embodiment, the pump is configured to removably receive a double-barreled cartridge for simultaneously dispensing first and second bone cement components. The system additionally includes a mixing chamber, for mixing the components sufficiently and reproducibly to fully automate the mixing and dispensing process within a closed system.
Bone cement components have conventionally been mixed, such as by hand, e.g., in mixing bowls in the operating room, which can be a time-consuming and unelegant process. The devices disclosed herein may be used with conventional bone cement formulations, such as manually mixed liquid-powder PMMA formulations. Alternatively, the use of a closed mixing device such as a double-barreled dispensing pump as disclosed herein is highly advantageous in reducing bone cement preparation time, preventing escape of fumes or ingredients, ensuring that premature cement curing does not occur (i.e., the components are mixed immediately prior to delivery into the body), and ensuring adequate mixing of components.
Two separate chambers contain respective materials to be mixed in a specific ratio. Manual dispensing (e.g., rotating a knob or squeezing a handle) forces both materials into a mixing nozzle, which may be a spiral mixing chamber within or in communication with a nozzle. In the spiral mixing nozzle, all or substantially all mixing preferably occurs prior to the bone cement entering the steerable injection needle and, subsequently, into the vertebra. The cement dispensing hand pump may be attached to the steerable injection needle permanently or removably via a connector, such as slip-ring Luer fittings. A wide range of dispensing pumps can be modified for use with the present invention, including dispensing pumps described in, for example, U.S. Pat. Nos. 5,184,757, 5,535,922, 6,484,904, and Patent Publication No. 2007/0114248, all of which are incorporated by reference in their entirety.
Currently favored bone cement compositions are normally stored as two separate components or precursors, for mixing at the clinical site shortly prior to implantation. As has been described above, mixing of the bone cement components has traditionally been accomplished manually, such as by expressing the components into a mixing bowl in or near the operating room. In accordance with the present invention, the bone cement components may be transmitted from their storage and/or shipping containers, into a mixing chamber, and into the patient, all within a closed system. For this purpose, the system of the present invention includes at least one mixing chamber positioned in the flow path between the bone cement component container and the distal opening on the bone cement injection needle. This permits uniform and automated or semi-automated mixing of the bone cement precursors, within a closed system, and thus not exposing any of the components or the mixing process at the clinical site.
Thus, the mixing chamber may be formed as a part of the cartridge, may be positioned downstream from the cartridge, such as in-between the cartridge and the proximal manifold on the injection needle, or within the proximal manifold on the injection needle or the injection needle itself, depending upon the desired performance of the device. The mixing chamber may be a discrete component which may be removably or permanently coupled in series flow communication with the other components of the invention, or may be integrally formed within any of the foregoing components.
In general, the mixing chamber includes an influent flow path for accommodating at least two bone cement components. The first and second incoming flow paths are combined, and mixing structures for facilitating mixing of the components are provided. This may include any of a variety of structures, such as a helical flow path, baffles and or additional turbulence inducing structures.
Tables 1-2 below depict the contents and concentrations of one exemplary embodiment of bone cement precursors. Chambers 1A and 1B contain precursors for a first cement composition for distribution around the periphery of the formed in place vertebral body implant with a higher particle concentration to promote osteoinduction, as discussed previously in the application. Chambers 2A and 2B contain precursors for a second cement composition for expression more centrally within the implanted mass within the vertebral body, for stability and crack arresting, as discussed previously in the application.
One of ordinary skill in the art will recognize that a wide variety of chamber or cartridge configurations, and bone cements, can be used with the present injection system. For example, in one embodiment, a first cartridge includes pre-polymerized PMMA and a polymerization catalyst, while a second cartridge includes a liquid monomer of MMA as is common with some conventional bone cement formulations.
In some embodiments, the contents of two cartridges can be combined into a single cartridge having multiple (e.g., four) chambers. Chambers may be separated by a frangible membrane (e.g., 1A and 2A in a first cartridge and 1B and 2B in a second cartridge, each component separated by the frangible membrane or other pierceable or removable barrier). In other embodiments, contents of the below cartridges can be manually pre-mixed and loaded into the input port of the injection system without the use of a cement mixing dispenser.
As illustrated in
The stylet may have a diameter of between about 0.030″ to 0.300″, 0.050″ to about 0.200″ and preferably about 0.100″ in some embodiments. The introducer cannula 800 is between about 8-14 gauge, preferably between about 10-12 gauge, more preferably 11 gauge in some embodiments. The introducer cannula 800, which may be made of any appropriate material, such as stainless steel (e.g., 304 stainless steel) may have a maximum working length of no more than about 12″, 8″, or 6″ in some embodiments. One or two or more bone cement cartridges, each having one or two or more chambers, may also be provided. Various other details of the components have been described above in the application.
One embodiment of a method for delivering bone cement into a vertebral body is now described, and illustrated in
The cement implantation procedure is designed for uni-transpedicular access and generally requires either a local anesthetic or short-duration general anesthetic for minimally invasive surgery. Once the area of the spine is anesthetized, as shown in
Once bone access has been achieved, as shown in
The actual injection procedure may utilize either one or two basic steps. In a one step procedure, a homogenous bone cement is introduced as is done in conventional vertebroplasty. The first step in the two step injection involves injection of a small quantity of PMMA with more than about 35%, e.g., 60% particles such as inorganic bone particles onto the periphery of the treatment site, i.e., next to the cortical bone of the vertebral body as shown in
Injection control for the first and second steps is provided by an approximately 2 mm inside diameter flexible introducer cannula 800 coupled to a bone cement injection pump (not shown) that is preferably hand-operated. Two separate cartridges containing respective bone cement and inorganic bone particle concentrations that are mixed in the 60% and 30% ratios are utilized to control inorganic bone particle to PMMA concentrations. The amount of the injectate is under the direct control of the surgeon or interventional radiologist by fluoroscopic observation. The introducer cannula 800 is slowly withdrawn from the cancellous space as the bolus begins to harden, thus preventing bone marrow/PMMA content from exiting the vertebral body 1308. The procedure concludes with the surgical incision being closed, for example, with bone void filler 1306 as shown in
The foregoing method can alternatively be accomplished utilizing the combination steerable needle of
At any time in the process, whether utilizing an injection needle having a cavity formation element or not, the steerable injector may be proximally withdrawn or distally advanced, rotated, and inclined to a greater degree or advanced into its linear configuration, and further distally advanced or proximally retracted, to position the distal opening 314 at any desired site for infusion of additional bone cement or other media. More than one cavity, such as two, or three or more, may be sequentially created using the cavity formation element, as will be appreciated by those of skill in the art.
The aforementioned bone cement implant procedure process eliminates the need for the external mixing of PMMA powder with MMA monomer. This mixing process sometimes entraps air, bone marrow and blood in the dough, thus creating porosity in the hardened PMMA in the cancellous bone area. These pores weaken the PMMA. Direct mixing and hardening of the PMMA using an implant procedure such as the above eliminates this porosity since no air, bone marrow or blood are entrapped in the injectate. This, too, eliminates further weakening, loosening, or migration of the PMMA.
A method of using the steerable injection system described, for example, in
Also disclosed herein is a steerable, curvable catheter that can be used to ablate tissue, such as bone, in a wide variety of applications including vertebroplasty or kyphoplasty. In some embodiments, prior to or concurrent with an orthopedic procedure such as vertebroplasty or kyphoplasty, it may be advantageous to remove bone or other tissue, such as sclerotic cancellous bone, in order to facilitate adequate filling of the interior of a vertebral body with bone cement or to create or enhance cavity formation in a kyphoplasty procedure. Systems, devices, and methods to facilitate removal of such tissue such as sclerotic cancellous bone will now be described. While one embodiment illustrated is a steerable, curvable dipole RF ablation catheter, catheters with one or more monopolar RF electrodes or catheters with a tip or other area(s) configured to ablate tissue with other energy modalities are also within the scope of the invention. For example, other types of energy that can be used to ablate tissue include laser, ultrasound such as focused ultrasound or high intensity focused ultrasound (HIFU), microwave, infrared, visible, or ultraviolet light energy, electric field energy, magnetic field energy, cryoablation, combinations of the foregoing, or other modalities. For some forms of energy, the energy can be launched from a source carried by the distal end of the catheter, such as, for example, ultrasound transducers, microwave coil arrays, laser light sources, and others as will be understood in the art. For the same, or other energy forms, the energy source may be coupled to the proximal end of the catheter and the energy propagated distally through the catheter to an energy interface at the distal end of the catheter. Energy may be propagated along any appropriate conduit or circuit, such as fiber optics, conductive wires, one or more lumens (e.g., for cryogenic media) or others as appropriate for the energy source.
Referring to
However, in other embodiments one or more energy delivery elements could be wirelessly activated via an external energy source. In some embodiments, the first RF electrode 1100 and the second RF electrode 1102 are separated by a distance of between about 0.1-10 cm, such as between about 0.5-5 cm, 1-3 cm, or about 2 cm in some embodiments depending on the desired area of treatment. The electrodes can be made of any appropriate material, such as a conductive, flexible corrosion resistant material such as copper, silver, or other metal and optionally coated with another metal such as gold or palladium. The antenna conduits 1101, 1103 can be shielded/insulated from the elongate tubular body 902 that conduits 1101, 1103 run along the outer diameter of by any appropriate material, such as, for example, a nonconductive coating or varnish. However, in other embodiments, one or more of the conduits 1101, 1103 run along the inside diameter of the tubular body 902, such as within a lumen configured to house the conduits 1101, 1103 therethrough. The distal elongate member 902 includes, in some embodiments, a relatively rigid proximal end or segment 924 and a distal deflectable end or segment 923 separated by a transition point 930 defining where the distal portion 923 is configured to be deflectable. The proximal segment 924 can be relatively straight and coaxial with the long axis of the proximal handle portion 1000. The distal segment 923 can be configured to be steerable and curvable through a working range via actuation of a control 901 on the handle 1000 that can be as described in detail supra in the application, such as, for example, at
In some embodiments, the catheter includes one or more thermocouple wires that can determine the temperature at the treatment site. The system could include a feedback system that shuts down power when the temperature exceeds a certain predetermined parameter. In some embodiments, the system is configured to heat the targeted tissue for ablation to a temperature of between about 45 and 90 degrees Celsius, or at or at least about 40, 50, 60, 70, 80, 90, 100, 110, or more degrees Celsius in other embodiments. In other embodiments, the temperature may be no more than about 110, 100, 90, 80, 70, 60, or 50 degrees Celsius, or less. In some embodiments, when a monopolar system is used a passive electrode, return electrode or ground pad replaces one of the first electrode 1100 or second electrode 1102. Other elements of RF systems that can be used with the catheter 900 described herein can be found, for example, in U.S. Pat. No. 6,749,624 to Knowlton or U.S. Pat. Pub. No. 2009/0082762 to Ormsby et al., both of which are hereby incorporated by reference in their entirety. In some embodiments, the catheter can incorporate a cooling system such as a supply lumen and a return lumen for providing a liquid cooling circuit running in the vicinity of the energy delivery element in order to cool tissue before, during, and/or after application of energy.
Generator 1120 can operate at any appropriate frequency. For an RF generator, the frequency could be less than about 30 Mhz, such as between about 375-500 kHz or between about 430-490 kHz or between about 460-480 kHz in some embodiments. The generator could have any appropriate power output depending on the desired clinical results, such as less than about 500 W, such as about 150 W, 200 W, or 250 W in some embodiments.
In some embodiments, the steerable energy delivery vertebroplasty catheter 900 can be used to create a cavity in a vertebral body wherein various types of bone cements can be injected as described supra in the application as well as those disclosed in U.S. patent application Ser. No. 11/626,336, filed Jan. 23, 2007, the disclosure of which is hereby incorporated in its entirety herein by reference.
In some embodiments, this procedure for creating a cavity or otherwise preparing the bone for inserting one of the bone cements described above is performed by making an incision in an appropriate location and inserting the distal portion of the steerable vertebroplasty catheter 900 to the desired osteotomy site. A number of features of this device minimize the degree of invasiveness required to perform this procedure: While the relatively low-profile diameter of the tube 902 minimizes the size of the incision required to guide the device to this location, the ability to change the angle of actuation of the distal segment 923 in which energy delivery members are attached to gives the user significant flexibility in determining the surgical approach for the desired location for making the osteotomy. Once the operator has maneuvered the distal segment 923 of the steerable vertebroplasty catheter 900 to the desired osteotomy site, the operator is then able to activate the energy delivery member(s). The operator can create a cavity therein by activating the energy delivery features of the catheter 900 in the center of the vertebral body thereby ablating the diseased bone. This can be facilitated through the use of the deflectable distal portion 923 of the tube 902 that enables the user to change the angle of deflection without changing the angle of approach. In this manner, a relatively large cavity can advantageously be created within the bone with only a minimally invasive approach and single entry site. One embodiment of this procedure is depicted in
Energy could be delivered to the target tissue for any appropriate time period depending on the desired clinical result. For example, in some embodiments tissue to be ablated could be heated to at least about 60, 70, 80, 90, or 100 degrees Celsius for less than about 5, 4, 3, 2, 1 minute or less. In some embodiments, tissue such as cortical or cancellous bone is heated to between about 90 to 110 degrees Celsius for between about 1 to 8 minutes, or between about 4 to 6 minutes. In some embodiments, the maximum current achievable to the vertebral body can be at or less than about 350 mA, 300 mA, 250 mA, or 200 mA.
Once a zone or cavity of sufficient size has been created within the vertebral body or other bone, the operator can then withdraw the steerable vertebroplasty ablation catheter 900 and introduce a device capable of injecting the desired bone cement or other compound into the cavity as described, for example, elsewhere in the application. As described below, in some embodiments, the cavity creation/ablation catheter and the cement injection catheter could be one and the same, so that the bone cement can be injected through a lumen extending through the ablation catheter.
Persons skilled in the art will recognize that the steerable vertebroplasty energy delivery catheter 900 can be used to drill into bones and tissues including soft tissue other than vertebrae and can be used in a variety of surgical applications. In addition, the device can be used for the purpose of cavity creation for the purpose of introducing chemotherapeutic or radiologic agents. The device can also be used for the purposes of mass reduction or elimination of various pathological tissues, e.g., treatment including destruction of cancerous tissue. The disclosures herein should not be construed as limiting the possible medical uses of the steerable vertebroplasty energy delivery catheter 900. In some embodiments, the energy delivery elements of the steerable, curvable catheter can be incorporated with the bone cement delivery elements on one catheter. For example, the ablation steerable, curvable catheter as described in
The energy delivery catheter 900 can deliver energy via other techniques than using RF electrodes. For example, the principles of cryoablation can be implemented in place of or in addition to using RF electrodes. Such cryoablation catheters can implement any combination of the features described above. A cryoablation catheter could be used in a variety of applications, including but not limited to ablation of malignant and benign tumors such as, for example, bone, lung, heart, liver, breast, prostate, skin, brain, bladder, uterus, and renal tumors; ablation of ectopic cardiac foci; and alleviation of pain, such as back pain via cryoablation of bony structures, such as a facet or sacroiliac joint, cryoablation, or relief of pain via neurolysis. In some embodiments, the deflectable catheters as described herein can be used for a cryoablation and vertebroplasty (CVT) procedure for cervical, lumbar, thoracic, or sacral primary or metastatic vertebral lesions.
Referring to
Cryogenic supply source 1201 can provide cryogen to the distal end 1202 of the catheter 1240 through a conduit, e.g., cryogen supply tube 1244. A cryogen connection tube 1242 can provide cryogen from cryogenic supply source 1201 to the cryogenic supply tube 1244.
A variety of substances can be used for cryogen. Examples of such substances include, but are not limited to, liquid nitrogen, helium, argon, hydrogen, oxygen and the like. A cryosurgical system based on liquid nitrogen is manufactured by Cryomedical Sciences, Inc. (Bethesda, Md.). A cryosurgical system based on argon gas is manufactured by EndoCare, Inc. (Irvine, Calif.). In addition, active thawing of an ablation zone (also referred to as an “ice ball”) can be achieved by the infusion of helium gas or the like into cryoprobes configured to cryoablate tissue, instead of the same substance as cryogen used for freezing.
In some embodiments, argon based systems can achieve a more rapid rate of freezing than liquid nitrogen based systems. Additionally or alternatively, argon based systems can provide a more precise control of temperature parameters and time parameters than nitrogen systems. For example, certain argon based systems that include insulated probes and rapid expansion of the gas in the sealed probe tip, can result in rapid cooling that reaches −100° C. within a few seconds. This rapid cooling is sometime referred to as the Joule-Thompson effect.
A cryogen substance can have a default temperature of, for example, less than 0° C., such as, for example, less than about −50° C., −100° C., −150° C., −180° C., −190° C., −200° C., or even less. A thawing substance can have a default temperature of, for example, 20° C. to 80° C., for example, 37° C. to produce immediate thawing. The temperature at each cryotip can be measured separately. In one embodiment, cryoprobes can be actively thawed for 10-15 min. until they reach approximately 25° C., 30° C., 37° C., or more, at which point they can be removed.
As previously noted, cryoablation catheters can include one, two, or more cryotips that can apply extreme cold to tissue to be ablated. For example, the illustrated cryoablation catheter 1240 includes cryotips 1240, 1242. A single cryotip may be sufficient for removing a smaller portion of tissue. For example if a portion of tissue is less, for example 6 cm, 5 cm, 4 cm, 3 cm, 2 cm, 1 cm, or less in dimension, e.g., length, width, diameter, and/or thickness, a single cryotip may be sufficient. In one embodiment, the entire deflectable distal segment 923 can be a cryotip. However, in certain embodiments, more cryotips may be desirable for ablating larger portions of tissue, providing finer control of the ablation process, or for ablating tissue faster. For example, at least 2, 3, 4, 5, 10, 15, 20, 25, 30, or more cryotips may be desirable to ablate portions of tissue having a dimension, e.g., length, width, diameter, and/or thickness larger than 3 cm, 3.5 cm, 4 cm, 5 cm, 6 cm, 8 cm, or 10 cm, or more. In some embodiments, each of the multiple cryotips may be controlled independently. In other embodiments, two or more cryotips may be controlled together. In some embodiments, all cryotip(s) can be included in distal segment 923. In other embodiments, one or more cryotips can be included in distal segment 923 and one or more cryotips can be included in other sections of the cryoablation catheter 1240. The diameter of a single cryoprobe that couples a cryotips can be, for example 1.2-2.4 mm or approximately 11-17 gauge. In some embodiments, each cryotip could extend circumferentially around the outer diameter of the catheter, or partially circumferentially around the outer diameter of the catheter depending on the desired clinical result.
The shaft of a cryoablation catheter can be made of material including, but not limited to, metals, stainless steel, nickel alloys, nickel-titanium alloys, thermoplastics, high performance engineering resins, fluorinated ethylene propylene (FEP), polymer, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane, polytetrafluoroethylene (PTFE), polyether block amide (PEBA), polyether-ether ketone (PEEK), polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysufone, nylon, perfluoro(propyl vinyl ether) (PFA), and combinations thereof.
In some embodiments, a cryo-insulation sheath configured to at least partially cover one, two, or more of the cryotips may be present and made of any suitable material which prevents a cryogenic effect from passing between the shaft and the tissue being treated. For example, the cryo-insulation sheath may be made of vacuum insulation. Other suitable cryo insulating materials include, without limitation, any closed cell foam such as Neoprene®.
The cryogenic supply tube 1244 may be made of any suitable material for delivering cryogen to the distal end of the shaft. In one embodiment, the cryogenic supply tube is made of stainless steel, but any other suitable material may be used. In another embodiment, the cryogenic supply tube can be made of copper.
Cryoablation time may vary from about 15 seconds to about 3½ hours, or longer. In some embodiments, tissue is ablated from 5 to 15 minutes depending upon the size of the region to be ablated. For example, cryoablation can continue for five minutes from the point at which the temperature around the tissue to be ablated is measured, for example, reaches −20° C. or below. In one embodiment, such a temperature can be measured by a temperature sensor. In such ablation, thawing can then be achieved by introducing warm helium gas through the same probes. The ice ball can subsequently melt within, for example, two minutes.
Cryogen can be delivered to a target tissue for any appropriate time period depending on the desired clinical result. For example, in some embodiments tissue to be ablated could be frozen to less than about −10, −25, −40, −50, −60, −70, −80, −90, or −100 degrees Celsius for less than about 20, 15, 10, 8, 5, 2, 1 minutes, 30 seconds, 20 seconds, or less. In some embodiments, tissue can be ablated from 5 to 15 minutes depending upon the size of the region to be ablated. In some embodiments, tissue such as cortical or cancellous bone can be frozen to between about −90 to −110 degrees Celsius for between about 1 to 15 minutes, or between about 5 to 10 minutes.
In one embodiment, a single freeze-thaw cycle can be performed. In other embodiments, two or more freeze-thaw-freeze cycles can be performed for each ablation zone. Each freeze-thaw-freeze cycle can last from 2-60 minutes, for example, it can be from 8-30 minutes. In some embodiments, each part of a freeze-thaw-freeze cycle can have a varying time. For example, a single freeze-thaw-freeze cycle can be preformed with 5-20 minutes for each freeze portion and 2-15 minutes for the thaw portion. In some embodiments, a freeze-thaw-free cycle can be for 10 minutes, 5 minutes, and 10 minutes, respectively. In other embodiments, a freeze-thaw-free cycle can be for 10 minutes, 8 minutes, and 10 minutes, respectively. These times can vary based on, for example, the size of the ablation zone and the number of cryotips.
Referring to
To achieve a cooling effect at the distal end 1202 of the catheter 1250, refrigerant is pre-cooled in a cooling apparatus 1225 prior to it being conveyed to a pressure line 1213. The cooling apparatus 1225 can include an isolated cooling chamber 1226, through which a tube 1227 can extend helically. The pressure line 1213 can be connected to the tube 1227. From a source of refrigerant, for example, a pressure cylinder 1228, a pressurized fluid can be supplied to the pressure line 1227. By means of an adjustable valve 1229, a specified quantity of pressurized fluid can be set.
In front of the valve 1229, a line can branch off from the refrigerant line which, via a restriction 1234, can open into the cooling chamber 1226. A quantity of fluid supplied into the cooling chamber 1226 can be set by means of a control valve 1230. When passing a restriction 1234, the refrigerant can expand inside the cooling chamber 1226, and, on doing so, can draw heat from the surroundings. For example, the refrigerant passing through the tube 1227 can consequently be cooled. The expanded fluid can be extracted from the chamber 1226 by a line 1231, so that a sufficient pressure difference is maintained across the restriction.
A temperature sensor 1212 can be arranged at the proximal end of the pressure line 1213 which can be in communication with measuring equipment 1223, for example, via signal line 1211. Thus, a temperature of the refrigerant supplied into the proximal end of the pressure line 1213, can be checked. On the basis of the measured temperature, the control valve 1230 can be set. In another embodiment, the control valve 1230 can be operated by a control apparatus on the basis of the temperature as measured with the sensor 1212.
A temperature sensor (not shown) can also be included near the distal end 1202 of the catheter 1250. This temperature sensor can be in communication with measuring equipment 1223, for example, via signal lines. With the aid of this temperature sensor, the temperature of the distal end 1202 of the catheter can be monitored. In some embodiments, a measured value can also be used to set control valve 1229. In another embodiment, operating the control valve 1229 can be done automatically in accordance with the temperature measured at the distal end 1202 of the catheter.
In some embodiments, at the deflectable distal end 1202 of the catheter 1250, an electrode that could be annular in some embodiments, (not shown) can be provided. This annular electrode can be in communication with measuring equipment 1223, for example, by means of a signal line. In certain embodiments, by means of the annular electrode in combination with an electrically conductive head (not shown), measurements can be taken inside tissues in order to determine the correct position for carrying out the ablation procedure.
The catheter 1250 can include a basic, generally tubular body 1215 with, at the distal end 1202, a closed head made of a thermally conductive material, for instance a metal. The head can include cryoprobe 1290. The generally tubular body 1215 can include one or more lumens 1220 which can serve as a discharge channel.
Inside the lumen 1220, a pressure line 1213 can be received, extending from the proximal end 1203 of the catheter 1250 to the distal end 1202. By means of a bonding agent, the pressure line 1213 can be secured in the head. During the manufacturing process, the distal end of the pressure line 1213 can be first secured in the head, after which the generally tubular body 1215 is pushed over the appropriate section of the head and fixed to it.
The pressure line 1213 can include a restriction at its distal end inside the head. The pressure line 1213 can be led outside the generally tubular body at a Y-piece 1206 in the catheter 1250. The pressure line 1213 and the signal lines can be led outside in the Y-piece 1206 in a sealed manner so that the discharge channel formed by the lumen 1220 remains separate.
Via the pressure line 1213, refrigerant under high pressure can be conveyed to the distal end 1202 of the catheter 1250. After passing the restriction, this refrigerant can expand, drawing heat from the surroundings. Because of this, the head will be cooled to a very low temperature.
The expanded gaseous fluid can return via a discharge channel formed by the lumen 1220, to the proximal end 1203 of the catheter 1250. Inside the handle 1204, the discharge channel can be sealed in an appropriate manner, and can be connected to a line 1232 which discharges the expanded fluid subsequently. A pump 1233 may be received in this line 1232, as is the case in the illustrated example of this embodiment, in order to ensure that also, in case of very small diameters of the catheter 1250, the expanded gas is discharged properly and that a sufficient pressure difference is maintained at the restriction in order to achieve the desired cooling effect.
The pressure line 1213 can be made of a synthetic material having, compared to metal, a low modulus of elasticity and a high thermal resistance coefficient. The catheter 1250, and in particular its distal end 1202, can be made adequately pliable because of the low modulus of elasticity of the material of which the pressure line 1213 has been made. For example, the synthetic material can be any one of many plastics, such as polyamide.
Due to the relatively high thermal resistance coefficient of the material of which the pressure line 1213 can be made, the pre-cooled fluid will typically, at the most, absorb only little heat from the surroundings. Inside the generally tubular body 1215 of the catheter 1250, the pressure line 1213 can extend through the central lumen 1220. The expanded gas which can be discharged from the head passes through lumen 1220. Initially, this expanded gas has a very low temperature and is heated only very slightly in the head. The gas passing through the discharge channel can still have, therefore, a low temperature, so that consequently, also no or only little warming up of the refrigerant supplied under pressure, will occur.
The section of the pressure line 1213 connected to the cooling apparatus 1225 can be provided with an isolation layer in order to prevent warming up of the pressure fluid.
Other elements of cryoablation systems that can be used with the catheter 1240 and/or 1250 described herein can be found, for example, in U.S. Pat. No. 5,807,391 to Wijkamp or U.S. Pat. No. 6,379,348 to Onik, both of which are hereby incorporated by reference in their entirety.
In some embodiments, a steerable cryoablation vertebroplasty catheter can be used to ablate a vertebral body wherein various types of bone cements can be injected as described supra in the application as well as those disclosed in U.S. patent application Ser. No. 11/626,336, filed on Jan. 23, 2007; application Ser. No. 12/029,428 filed on Feb. 11, 2008; application Ser. No. 12/469,654 filed on May 20, 2009; and U.S. Provisional App. No. 61/300,401 filed on Feb. 1, 2010, all of which are hereby incorporated by reference in its entirety. In some embodiments, a steerable, curvable vertebroplasty injector could include one, two, or more cavity creating elements as described in the Ser. No. 12/469,654 application as well as one, two, or more ablation elements as described herein for a multi-function injector, cavity creator, and/or ablation catheter.
In some embodiments, this procedure for creating a cavity or otherwise preparing the bone for inserting one of the bone cements described above is performed by making an incision in an appropriate location and inserting the distal portion of the steerable cryoablation vertebroplasty catheter to the desired osteotomy site. A number of features of this device minimize the degree of invasiveness required to perform this procedure, which include, but are not limited to, substantially the same features as described above in connection with the steerable energy delivery vertebroplasty catheter 900. One embodiment of a minimally invasive procedure utilizing such features is depicted in
Referring to
In operation, combined electrosurgical-cryosurgical instrument 1310 may be inserted into tissue near the site to be ablated. The combined electrosurgical-cryosurgical instrument 1310 can include substantially the same steerable curvable functionalities as the other catheters described herein, including, but not limited to, a distal deflectable segment 923 as previously described.
RF generator 1120 can be used to deliver electrical energy to the distal end of shaft 1330, and cryogen supply source 1201 may be used to provide a cryogenic effect at the distal end of shaft 1330. A tissue can be ablated around the radiofrequency-noninsulated portion 1340 of shaft 1330. Similarly, tissue can be ablated around the cryo-noninsulated portion 1340 of shaft 1330.
Combined electrosurgical-cryosurgical instrument 1310 can also be used to ablate tissue using a combination of RF and cryo techniques described herein. For example, this may be accomplished by supplying the distal end of the shaft with both radiofrequency energy and a cryogenic effect, either sequentially or simultaneously. The resulting ablation may possess the advantages of both radiofrequency ablation and cryoablation. For example, the ablated area may be as large as an area created by certain cryoablation techniques, but not exhibit the toxicity effects that are associated with such cryoablation techniques upon breakdown.
Moreover, the principles and advantages described above in reference to any of the RF ablation or cryoablation catheters can be combined based on at least the concepts disclosed in reference to
While described herein primarily in the context of vertebroplasty, one of ordinary skill in the art will appreciate that the disclosed energy delivery catheter can be used or modified in a wide range of clinical applications, such as, for example, other orthopedic applications such as kyphoplasty, treatment of any other bones, pulmonary, cardiovascular, gastrointestinal, gynecological, or genitourinary applications. While this invention has been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention. For all of the embodiments described above, the steps of the methods need not be performed sequentially. Additionally, the skilled artisan will recognize that any of the above-described methods can be carried out using any appropriate apparatus. Further, the disclosure herein of any particular feature in connection with an embodiment can be used in all other disclosed embodiments set forth herein. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above.
This application claims priority under 35 U.S.C. §120 as a continuation application of U.S. patent application Ser. No. 12/987,923 filed Jan. 10, 2011 which is a continuation application of U.S. patent application Ser. No. 12/784,371 filed on May 20, 2010, which in turn claims priority under 35 U.S.C. §119(e) as a nonprovisional of U.S. Provisional App. No. 61/180,058 filed on May 20, 2009. All if the aforementioned priority applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 61180058 | May 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12987923 | Jan 2011 | US |
| Child | 13219445 | US | |
| Parent | 12784371 | May 2010 | US |
| Child | 12987923 | US |
