US 20060085054 A1
One embodiment comprises an apparatus for applying energy to a hollow anatomical structure having an inner wall. The apparatus comprises an elongate shaft having a distal end and a proximal end opposite the distal end; and a capacitive treatment element located near the distal end. The capacitive treatment element is sized for insertion into the hollow anatomical structure and placement near the inner wall. The capacitive treatment element is configured to create an electric field that extends at least partially into the inner wall. Other devices and methods for treatment of hollow anatomical structures are disclosed as well.
1. An apparatus for applying energy to a hollow anatomical structure having an inner wall, said apparatus comprising:
an elongate shaft having a distal end and a proximal end opposite said distal end;
a capacitive treatment element located near said distal end;
said capacitive treatment element being sized for insertion into said hollow anatomical structure and placement near said inner wall;
said capacitive treatment element being configured to create an electric field that extends at least partially into said inner wall.
2. The apparatus of
3. The apparatus of
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9. The apparatus of
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11. The apparatus of
12. An apparatus for applying energy to a hollow anatomical structure having an inner wall, said apparatus comprising:
an elongate shaft suitable for insertion into said hollow anatomical structure; and
a dielectric heating element connected to said shaft.
13. The apparatus of
14. The apparatus of
15. The apparatus of
16. The apparatus of
17. The apparatus of
18. The apparatus of
19. A method of treating a hollow anatomical structure, said method comprising:
inserting a capacitive treatment element into said hollow anatomical structure;
positioning said capacitive treatment element near an inner wall of said hollow anatomical structure;
with said capacitive treatment element, creating an electric field that extends at least partially into said inner wall.
20. The method of
21. The method of
22. The method of
23. The method of
24. The method of
positioning said capacitive treatment element in a first portion of said vein;
energizing said capacitive treatment element while it is in said first portion;
reducing or shutting off power delivery to said capacitive treatment element after energizing said capacitive treatment element while it is in said first portion;
after reducing or shutting off power delivery to said capacitive treatment element, moving said capacitive treatment element to a second portion of said vein; and
energizing said capacitive treatment element while it is in said second portion.
25. The method of
This application claims the benefit under 35 U.S.C. § 119(e) of each of the following U.S. Provisional Patent Applications: No. 60/608,335, filed Sep. 9, 2004, titled CATHETER WITH THERMAL ELEMENT FOR LIGATION OF HOLLOW ANATOMICAL STRUCTURES; No. 60/617,621, filed Oct. 8, 2004, titled ELECTRODE ELEMENT SYSTEMS; No. 60/618,827, filed Oct. 13, 2004, titled CATHETER WITH THERMAL ELEMENT FOR LIGATION OF HOLLOW ANATOMICAL STRUCTURES; No. 60/621,251, filed Oct. 22, 2004, titled VEIN CONFORMING CATHETER; No. 60/624,009, filed Nov. 1, 2004, titled CATHETER WITH THERMAL ELEMENT FOR LIGATION OF HOLLOW ANATOMICAL STRUCTURES; No. 60/645,964, filed Jan. 21, 2005, titled HOLLOW ANATOMIC STRUCTURE CONFORMING CATHETER; No. 60/659,287, filed Mar. 7, 2005, titled CATHETER WITH THERMAL ELEMENT FOR LIGATION OF HOLLOW ANATOMICAL STRUCTURES; and No. 60/664,316, filed Mar. 22, 2005, titled CATHETER WITH CAPACITIVE ELEMENT FOR TREATMENT OF HOLLOW ANATOMICAL STRUCTURES. The entirety of each of the above-mentioned provisional patent applications is hereby incorporated by reference herein and made a part of this specification.
1. Field of the Inventions
Certain embodiments disclosed herein relate to methods and devices for treating hollow anatomical structures such as varicose veins.
2. Description of the Related Art
The human venous system of the lower extremities consists essentially of the superficial venous system and the deep venous system with perforating veins connecting the two systems. The superficial system includes the long or great saphenous vein and the small saphenous vein. The deep venous system includes the anterior and posterior tibial veins which unite to form the popliteal vein, which in turn becomes the femoral vein when joined by the short saphenous vein.
The venous system contains numerous one-way valves for directing blood flow back to the heart. Venous valves are usually bicuspid valves, with each cusp forming a sack or reservoir for blood. Retrograde blood flow forces the free surfaces of the cusps together to prevent continued retrograde flow of the blood and allows only antegrade blood flow to the heart. When an incompetent valve is in the flow path, the valve is unable to close because the cusps do not form a proper seal and retrograde flow of the blood cannot be stopped. When a venous valve fails, increased strain and pressure occur within the lower venous sections and overlying tissues, sometimes leading to additional, distal valvular failure. Two venous conditions or symptoms which often result from valve failure are varicose veins and more symptomatic chronic venous insufficiency.
One embodiment comprises an apparatus for applying energy to a hollow anatomical structure having an inner wall. The apparatus comprises an elongate shaft having a distal end and a proximal end opposite the distal end; and a capacitive treatment element located near the distal end. The capacitive treatment element is sized for insertion into the hollow anatomical structure and placement near the inner wall. The capacitive treatment element is configured to create an electric field that extends at least partially into the inner wall.
One embodiment comprises an apparatus for applying energy to a hollow anatomical structure having an inner wall. The apparatus comprises an elongate shaft suitable for insertion into the hollow anatomical structure; and a dielectric heating element connected to the shaft.
One embodiment comprises a method of treating a hollow anatomical structure. The method comprises inserting a capacitive treatment element into the hollow anatomical structure; positioning the capacitive treatment element near an inner wall of the hollow anatomical structure; and, with the capacitive treatment element, creating an electric field that extends at least partially into the inner wall.
One embodiment is an apparatus for applying energy to a hollow anatomical structure having an inner wall. In one such embodiment, the apparatus comprises a heat emitter containing an electrically resistive fluid. The heat emitter generates heat in the resistive fluid by passing an electrical current through the fluid. The heat emitter can be positioned within a hollow anatomical structure in order to ligate a portion of the hollow anatomical structure.
An alternative embodiment of an apparatus for applying energy to a hollow anatomical structure having an inner wall comprises a heat emitter containing a heating medium that has a self-regulating maximum temperature associated with a phase change of the heating medium. The heat emitter is generally configured to be positioned within the hollow anatomical structure.
Another embodiment comprises a method of treating a hollow anatomical structure having an inner wall. The method comprises positioning a heating element in a first position in said hollow anatomical structure. The heating element has a length and a width measured orthogonal to the length. The length of the heating element is preferably greater than the width. While in a first position, the heating element is operated and emits heat from substantially all of its length. The heat is emitted into the inner wall of the hollow anatomical structure. The element is subsequently moved to a second position within the anatomical structure by a distance corresponding to approximately the structure's length. While stationary in this position, the element is again operated and again emits heat into the inner wall along substantially the length of the element. In one embodiment, the element is turned off before it is moved to the second position.
In another embodiment is also an apparatus for applying energy to a hollow anatomical structure comprises a catheter sized for at least partial insertion into the hollow anatomical structure. The catheter has a heat-emission region, which in turn has a length and a width measured orthogonal to the length. The length of the heat emission region is preferably greater than its width. The heat-emission region emits heat at a substantially uniform temperature along substantially all of its length.
In some embodiments, methods of adjusting an operating temperature of the system are provided. In one embodiment, the operating temperature can be adjusted by adjusting a relief valve. In another embodiment, the operating temperature of the system can be adjusted by choosing or adjusting the fluid used in the system. In another embodiment, the operating temperature of the system can be varied by adjusting both a relief valve and varying the properties or amount of a fluid.
One embodiment is an apparatus for applying energy to a hollow anatomical structure having an inner wall. In one such embodiment, the apparatus comprises a heating element configured to create an electric field that extends at least partially into a tissue of a surrounding HAS in which the device is positioned. The heating element generates heat in the surrounding fluid and/or tissue by causing movement of dipolar molecules in the surrounding fluid/tissue.
In one embodiment, a capacitive heating element comprises a pair of elongate parallel electrodes separated by a non-conductive element. The non-conductive element can comprise an air gap, a solid non-conductive material, or a combination thereof. In another embodiment, a capacitive heating element comprises two pairs of elongate parallel electrodes separated by non-conductive elements. In further embodiments, a capacitive heating element can include three or more pairs of elongate parallel electrodes separated from one another by electrically non-conductive elements. In further embodiments, a capacitive heating element can include a plurality of electrodes wrapped in a helical pattern around a solid or hollow central core. In another embodiment, a capacitive heating element comprises a plurality of ring-shaped electrodes. In each of the above embodiments, the electrodes can be configured to be joined to a power source in order to apply electric fields across adjacent electrodes such that the electric fields extend outwards from the radial extent of the device.
In one embodiment, a catheter comprises an elongate shaft and an electrode element located distal of the elongate shaft. A sheath is slidably disposed on the shaft. The sheath and catheter are relatively moveable between a first configuration in which the sheath covers substantially all of the electrode element, and a second configuration in which the sheath covers less than substantially all of the electrode element. The electrode element may be energized by an energy source using alternating current in the RF range.
In another embodiment, a catheter system comprises an elongate shaft and an energy-emission element located distal of the elongate shaft. The energy-emission element includes a plurality of emission segments, a plurality of the segments are independently operable to emit energy into the surroundings of the energy-emission element. Optionally, the catheter system further comprises a power source drivingly connected to the emission segments. The power source is operable pursuant to a multiplexing algorithm to deliver power to, and operate, the emission segments in a multiplexed fashion. In one embodiment, the energy-emission element comprises an electrode element. The electrode element may be energized by an energy source using alternating current in the RF range. In one embodiment, the electrode comprises an RF emitter.
In another embodiment, a catheter system comprises an elongate shaft and an energy-emission element located distal of the elongate shaft. The energy-emission element has an effective axial length along which the energy-emission element emits energy. The effective axial length is adjustable.
In another embodiment, a catheter comprises an elongate shaft and one or more expandable members located on the elongate shaft. One or more electrode elements are positioned on the one or more expandable members. The one or more electrode elements may be energized by an energy source using alternating current in the RF range.
In another embodiment, a device for treating a hollow anatomical structure comprises an elongate structure with an energy-delivering distal portion. The distal portion is movable between a first position with a minimal transverse dimension and a second position with a maximum transverse dimension, wherein the maximum transverse dimension of the planar shape is selected to engage an internal wall of the hollow anatomical structure sufficiently to cause the hollow anatomical structure to conform to the shape of the distal portion.
Certain disclosed embodiments comprise a device and/or a method capable of providing heat energy along a circumferential band to a vein wall over a specific length without localized boiling, the likelihood of recurrence due to neovascularization, excessive pain levels & recovery times, coagulum build-up causing incomplete treatments, long treatment times from having to pull back the catheter, and the issue of variable pullback rates causing incomplete treatments and the subsequent need for re-treatment.
In one embodiment, a catheter includes a plurality of primary leads to deliver energy for ligating a hollow anatomical structure. Each of the primary leads includes electrodes located at the working end of the catheter. The primary leads are constructed to expand outwardly within a single plane for the purpose of conforming the hollow anatomical structure it is placed within to the expanded profile of the catheter. In doing so, the hollow anatomical structure is placed into apposition with the electrodes. Energy can then be applied from the leads to create a heating effect in the surrounding tissue of the anatomical structure. The diameter of the hollow anatomical structure is reduced by the heating effect, and the electrodes of the primary leads are moved closer to one another as the diameter reduces. Where the hollow anatomical structure is a vein, energy is applied until the diameter of the vein is reduced to the point where the vein is occluded. The catheter can include a lumen to accommodate a guide wire or to allow fluid delivery.
Certain devices and methods disclosed herein are capable of more evenly distributing energy along the target hollow anatomical structure utilizing lower temperatures and the ability to regulate power via a temperature feedback loop in a continuous simultaneous length.
Devices and methods disclosed herein are preferably suitable for ligation of hollow anatomical structures in the body, including but not limited to varicose veins generally, perforator and superficial veins, as well as hemorrhoids, esophageal varices, and also fallopian tubes.
Certain objects and advantages of the invention are described herein. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of the embodiments summarized above are intended to be within the scope of the invention herein disclosed. However, despite the foregoing discussion of certain embodiments, only the appended claims (and not the present summary) are intended to define the invention. The summarized embodiments, and other embodiments of the present invention, will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed.
FIGS. 77A-F illustrates embodiments of distal flexible components for use in an HAS conforming device.
Referring now to
Contained within the catheter shaft 12 is a fluid lumen 34. The fluid port 16 communicates with the interior of fluid lumen 34, with the interior of catheter shaft 12 and with a manually adjustable pressure relief valve 20. The fluid lumen 34 terminates just proximal to the tip 36 and allows fluid to flow into the interior of catheter shaft 12. The electrically conductive fluid or liquid can flow from the reservoir 18, through the fluid port 16, through the fluid lumen 34, into the catheter shaft 12, thus surrounding the positive RF wire 26 and the negative RF wire 30. The fluid lumen 34 can be used to infuse additional fluid into the catheter shaft 12. This additional fluid may become necessary as a replacement for fluid that has changed phase, formed vapor bubbles and moved up the catheter shaft 12 toward the pressure relief valve 20. Replacement fluid can be slowly dripped into the catheter shaft 12 at a rate sufficient to keep the system functioning, but not so much that the added fluid would cool the catheter shaft 12 too much. In one embodiment, the fluid lumen 34 can have an outside diameter of about 0.5 mm to 1 mm.
The catheter shaft 12 can be vented to ambient air via the pressure relief valve 20. This valve can be used to build, maintain and/or relieve pressure in the system and tune the boiling point as desired. As the fluid is heated to its boiling point, the gaseous bubbles that form within the shaft 12 interrupt the path of the electrical energy as it flows through and heats the fluid. As the fluid temperature increases, the presence of more and more bubbles increases this inhibiting effect. Accordingly, the creation of bubbles (and/or the retention of bubbles in the conduction path(s) between the exposed portions of the wires 26, 30) is one mechanism that can be used to control the temperature of the system. Bubbles created through boiling can be controllably released through the pressure relief valve 20, discussed above.
In addition, at a given pressure (which can be set via the pressure relief valve 20) the conductive fluid has an inherent or “self-regulating” maximum temperature or boiling point which in turn sets an inherent or “self-regulating” maximum temperature of the working end of the catheter. This advantageously provides an effective safety feature for the catheter, which can be set to prevent overheating of the treated tissue and/or to preclude the need for a temperature feedback loop that actively governs power delivery to achieve a desired set-point temperature.
In some embodiments, electrically conductive fluids of varying degrees of viscosity, and conductivity might be employed. Such fluids might include saline, water, biocompatible oils, dextrose solution, and the like. The fluid is chosen to get a desired boiling point. The boiling point can be derived from a desired treatment temperature (for example, a treatment temperature of 100° might require a conductive-fluid boiling point of 113°, given potential losses in the catheter system, and potential losses in the thermal coupling of the catheter to the wall of the HAS in which the catheter is employed). Thus, a temperature of the working end can be controlled by controlling the boiling point of the fluid (for example, by choosing a fluid with a particular boiling point), by controlling a flow rate of the fluid through the system, or by controlling the pressure at which the pressure valve vents.
The following table shows examples of liquids that can be used alone or mixed in such a system, including the boiling points of the liquids at one atmosphere (1 atm), or seven hundred and sixty torr (760 mm Hg).
The catheter shaft 12 can include an atraumatic tip 36 for facilitating manipulation of the catheter into the HAS of the patient. The tip 36 is preferably tapered inward or rounded at its distal end, or the tip 36 can have other shapes that facilitate threading or tracking of the catheter through the bends in the vascular system.
In one embodiment, the tip 36 can, for example, be fabricated from a polymer having a soft durometer, such as 70 Shore A. Further, the tip can be fabricated from any number of materials with varying durometer such as pebax, polyimide, polyethylene, silicone (softer more atraumatic materials) or stainless-steel or ceramic as a blunt tip. Additionally, the tip might employ an endostructure or exostructure to define its flexibility characteristics.
A second embodiment of the catheter, depicted in
An outer sheath 38 can be used to enclose and straighten the coiled catheter shaft 36 for introduction into and advancement through the HAS to be treated. In certain embodiments, the outer sheath 38 can be retractable, and the treatment length can be adjusted by actuating the retractable outer sheath 38 from outside of the body. This can be done by introducing the catheter into the body with the sheath 38 covering an active portion of the catheter and advancing the tip to the treatment site. The sheath 38 can then be withdrawn until the length of the active portion matches the length of the desired treatment area. The retractable sheath 38 can accordingly insulate adjacent tissue from thermal damage.
One embodiment of the inventions comprises a method of treating a HAS by gaining HAS access; inserting a catheter with an outer access sheath into the HAS; positioning the tip of the catheter near the saphenofemoral junction or other desired treatment starting point in the HAS; withdrawing the protective outer sheath to allow the catheter to assume a deployed (e.g. helical) shape (see the coiled catheter shaft 36 of
Referring now to
Referring now to
In some embodiments, a catheter can include holes positioned along the length of the catheter tube to allow fluid to escape and heat the surrounding tissue. Furthermore, in an embodiment where such holes are present, higher fluid flow rates and pressure can be maintained to force small jets of liquid against and/or into the wall of the target anatomical structure.
In some embodiments, the sheath 80 is made of a material that can withstand high temperatures, such as Polyamide, Teflon or Ultem. This sheath 80 is preferably sufficiently lubricious to allow introduction into the HAS, to facilitate navigation through the HAS to the desired treatment site, and to prevent blood coagulum build-up on its exterior. The sheath 80 can therefore be coated with a lubricious and/or non-stick coating, comprising Teflon or Paralyene, for example. The outer sheath 80 may also be made from a suitable kink-resistant material, such as braided Polyimide, for example.
As shown in
In some embodiments, the energy element 81 extends along substantially the entire length of the outer sheath 80 so that the inner member tip is adjacent the tip of the outer sheath 80. In some embodiments, the energy element 81 may extend a finite length, for example 45 cm, measured from the distal tip of the outer sheath 80 towards the proximal handle 14. Preferably, the length of the energy element 81 generally corresponds to the desired length of the HAS to be treated.
In some embodiments, energy is transferred from the energy element 81 to a HAS via a fluid located within the outer sheath 80 and surrounding the energy element 81 within a fluid chamber 86. In some embodiments, the fluid is introduced into the fluid chamber 86 as a liquid which is then heated above its boiling temperature, thereby causing a phase change that initiates production of gas (such as steam when the liquid is water). Once the fluid pressure of the gas exceeds a threshold pressure, the gas is forced through the micro-perforations in the outer sheath 80 towards the HAS. Before the fluid pressure within the fluid chamber 86 exceeds the threshold pressure, the micro-perforations remain closed, thereby retaining the heated fluid within the fluid chamber 86.
The liquid may be delivered into the fluid chamber 86 via an internal lumen 83 extending longitudinally through the energy element 81. In some embodiments, the energy element 81 comprises only a single distal opening such that fluid may exit through only the very distal tip of the energy element 81. The energy element 81 further comprises a proximal opening (not shown) configured to allow a fluid to enter the lumen in the handle 14 via a connector 20 from an auxiliary fluid source 18 (see
In some embodiments, the fluid is heated through direct contact with the energy element 81. The energy element 81 heats the liquid via regulated power delivery from the energy source 24 (see
The boundaries of the fluid chamber 86 are defined by the outer sheath 80, the distal tip, and a proximally-placed seal component 84 that seals around the energy element 81 and abuts the inner walls of the outer shaft 80. The seal is preferably substantial enough to prevent undesired leakage at the expected operating fluid pressures. Thus, in some embodiments, the fit between the seal component 84 and the energy element 81 is an interference fit. Additionally, a material from which the seal component 84 is made will preferably be substantially resistant to high temperatures and will provide a good sealing force. In some embodiments, the sealing component comprises a Silicone material. Alternatively, the sealing component can be made of Pebax, Santoprene, PET, or other suitable material. A seal component can be formed by molding, casting, machining or otherwise shaping from a suitable material.
In some embodiments, the length of the fluid chamber 86 can be adjusted by varying an axial placement of the seal 84. For example, in some embodiments this adjustment is performed by actuating an attached seal actuation member 85. This actuation member 85 is preferably strong enough and attached to the seal 84 with enough strength to allow for significant ‘pushability’ as well as ‘pullability’ since it has to overcome a relatively large frictional force created by the internal seal. Therefore, in some embodiments, the actuation member 85 can be a tube made of a material capable of providing significant column strength while still bonding well to the seal, such as stainless-steel or Hytrel. Actuation of the member 85 may be facilitated by any suitable mechanism located at the proximal catheter handle 14.
With reference now to
In the embodiment illustrated in
In some embodiments, a thin electrically insulative material 104 such as polyimide, Teflon or silicone tape may be helically wound around the inner lumen assembly (e.g., the inner lumen 102 and the electrodes 101). The insulative material 104 can be about 0.003 inches to about 0.020 inches thick. However, material thicknesses outside of this range can also be used.
Helically winding an electrically insulative material 104 around the electrodes 101 can effectively form multiple discrete shorter electrodes from each longer electrode 101. When the sections of exposed electrodes are equal in surface area along each strip (each exposed section having a corresponding exposed section of approximately similar dimensions on the other electrode 101), the heat produced starts near the signal wire attachment section and eventually propagates along the electrodes 101 to the distal end. For example, the portions of the electrodes 101 nearest the attachment point of the signal wire 103 can be hotter than those portions of the electrodes 101 farther away from that attachment point. The pitch of the helical tape windings of the insulative material 104 can be varied as shown in
Alternatively, the wires 122 can wind helically through the tube wall to promote overall device flexibility.
The isometric view of
Yet another variation can be to have a common wire, which has exposed section windows, and each of the other wires defines a treatment length by its section of skived window electrodes. This version typically reduces the number of wires required, yet the device could nonetheless be operated in a multiplexed fashion, as discussed above.
Any of the energy elements depicted in
In some preferred embodiments, the balloon 131 can be made from substantially elastic materials such as silicone, or C-FLEX (i.e. any of the family of materials manufactured and sold under the trademark C-FLEX by CONSOLIDATED POLYMER TECHNOLOGIES, INC. based in Clearwater, Fla.). These balloons are typically adjustable in diameter and can expand to fit within many different HAS diameters. Alternatively, the balloon can be made of PET or similar inelastic materials which predefine the balloon size. The balloon can be expanded or collapsed by at least one fluid port located on the catheter shaft and inside the balloon section. This fluid port can be configured to communicate with another lumen that runs internal to the outer catheter shaft, and it can exit in the handle 14 (see
As the balloon 131 is expanded, it can also displace any fluid, such as blood, present in the immediate treatment area of the HAS. This fluid displacement can facilitate treatment of the HAS further by removing possible heat sinks and focusing the heat more directly into the wall of the HAS.
The balloon 131 can further be configured to collapse as the HAS itself is collapsing in response to the applied treatment. By evaluating the amount of fluid forced out of the balloon at the catheter handle, treatment success or completion can be indicated. The balloon can be inflated with fluid so as to completely fill the volumetric portion of the vein it is delivering treatment to. If the fluid is then allowed to be squeezed out by the surrounding and collapsing vein wall (typically via a release valve at the proximal handle), then the amount of vein collapse can be determined by correlating the ejected fluid volume with the reduction in the internal volume of the treated HAS segment. Since HAS collapse is indicative of a successful treatment, the amount of fluid released at the proximal handle valve can be measured to indicate treatment completion.
The balloon 131 can also be manually collapsed during the last portion of the treatment cycle. This manual collapse can allow the natural collapse of the HAS being treated.
Except as further described herein, the catheters of
Exemplary, but non-limiting embodiments of the devices of
Some equipment that can be used is set forth in this list: soldering iron; UV light source; ruler; razor blades; plastic toothpicks; scalpel and blades; tweezers; cutting tweezers; microscope; EFD dispensing tips; syringe (e.g., 3 cc); foam swabs.
The following list and figures describe a procedure that can be used for preparation and assembly of an embodiment of the inventions described herein.
The following list describes an example of a setup and testing procedure and method for using embodiments of the inventions described above:
Many materials, both electrically conductive and non-conductive, dissipate energy when subjected to an alternating electric field through a process known as dielectric heating. Dielectric heating generally works by causing rapid movement of dipolar molecules (such as water) within a material by applying a rapidly alternating electric field, thereby causing the dipolar molecules to rapidly re-orient according to the orientation of the field. The quantity of energy dissipated in the form of heat when the material is placed in an alternating electric field depends on a material property called a “dielectric loss factor.” The dielectric loss factor of a material is the product of the Dielectric Constant of the material (Er) and the Loss Tangent (tan δ) of the material.
Dipolar molecules have both positive and negative charges separated by a small distance. When an electric field is created in the vicinity of dipolar molecules, the molecules are forced to align with the field. As the polarity of the electric field alternates, the dipolar molecules rotate to align to the new field orientation. This rapid movement of the molecules effectively heats the material by internal friction. Thus, materials with more polar molecules will tend to have higher dielectric loss factors than materials with fewer polar molecules. Non-polar materials such as fat and dry tissue do not react to the electric field, and therefore, are not directly heated by capacitive RF energy.
In a typical good quality, low loss capacitor used in electronic applications, it is desirable to reduce the effects of dielectric heating. Thus, the dielectric materials of such capacitors typically have relatively low dielectric loss factors as a result of a high dielectric constant (i.e., a higher number of molecules that react to the electric field) and a small loss tangent (i.e., a measure of how much energy is lost to molecular friction). However, in situations where it is desirable to heat the dielectric material, the dielectric material preferably has a relatively large loss factor as a result of a larger loss tangent. In both cases, the dielectric material preferably includes a sufficiently high dielectric constant to achieve the desired degree of capacitance.
The degree of the dielectric heating effect depends upon the frequency of the AC power used, the RF voltage field and the loss factor of the material being heated. The equation shown below determines the heating effect:
From this expression, it is apparent that power dissipation in the dielectric material increases proportionally with frequency, dielectric constant, and loss tangent.
Unlike polymeric and ceramic materials used for making most capacitors for electronic applications, the dielectric properties of biological materials change more rapidly with changing frequency. For example, as illustrated in the following table, dielectric constant (εr) and loss tangent (tanδ) increase at increasing applied frequencies:
Applying the earlier formula for volumetric heating using the values in the preceding table, and using an electric field strength of 10,000 V/m yields:
Thus, as shown above, with all other things being equal, the highest dissipation of heat occurs in saline, and then in blood, with heat dissipation to the vessel wall occurring the slowest.
Radiofrequency generators will generally output power efficiently over a finite range of impedance and phase angle. If the source and the load impedances are not matched, a reduced amount of power is transmitted from the source to the load. In the case of dielectric heating, the load is represented by the parallel resistance created by the properties of the capacitor, i.e., dielectric constant and loss tangent.
Dielectric resistivity manifests itself both as a series and a parallel resistance with the pure capacitance. Generally, a low series resistance and high parallel resistance. The impedance presented to the RF generator is then the parallel impedance of the Rp and Cp in series with the series resistor, Rs. Since this impedance varies with frequency, either steps to match the impedance with the RFG should be performed, or an operating frequency should be selected to match the impedance of the circuit. Coupling the electric field through the dielectric is generally easier when operating at higher frequencies, because the impedance experienced by the capacitive device is lower at higher frequencies.
The electrodes 510A, 510B, 560A, 560B, 560C, 560D, 610A, 610B, 660A-E are preferably separated by electrically non-conductive, insulative segments 520, 570, 620, 670. For example, as shown in
The outer non-conductive sheath 515, 565, 615, 665 surrounding the electrodes preferably are made of a material that is substantially electrically non-conductive, yet is substantially “invisible” to the RF field at the applied frequency. For example, many polymers will have sufficiently few dipolar molecules as to be substantially unaffected by the alternating electric field across the electrodes elements. It is believed that, at sufficiently high frequencies (e.g., about 10 to about 30 MHz), materials such as PET, PTFE, FEP, PE Polyolefin (or other materials with dielectric constants and loss tangents that are appreciably less than the same properties of the biological structure to be treated) will be substantially unaffected by RF power in the electrodes. The thickness of the outer sheath is typically minimized to substantially limit the amount of heating experienced by the sheath, yet remains thick enough to provide adequate electrical insulation and to resist melting due to contact with the heated tissue.
In an alternative embodiment, illustrated for example in
In an alternative embodiment, illustrated for example in
In some embodiments, the electrodes extend along substantially an entire desired working length. For example, in some embodiments, the electrodes can have an operative length of anywhere from one to sixty cm. For example, in some embodiments, total working lengths of 9 cm, 15 cm, 30 cm, 45 cm or other lengths can be used as desired. In some embodiments, variable length treatment devices may be constructed by providing a plurality of discrete segments along the axis of the device. The operative length of the device can then be varied by activating or de-activating one or more pairs or sets of discrete segments as desired.
The elongate electrodes can be made of any suitable material, such as copper or other conductive metallic tape, etched flex circuits, metalized polymer substrates (e.g., formed by vapor deposition or other process). In some embodiments, a metallic tape can be co-extruded into an elongate catheter. In some embodiments, the electrodes are preferably substantially flexible to allow the device to be guided to a desired treatment site.
Embodiments of methods for using devices such as those illustrated in
In some embodiments, any of the devices of
The devices of
Although many of the forgoing embodiments have been described in the context of treating a hollow anatomical structure (such as a blood vessel), it should be understood that the above embodiments are not necessarily limited to such uses. For example, the systems and devices described herein can be used for any clinical procedure in which it is desirable to apply energy to anatomical, biological, or foreign structures within a patient.
In some respects, some embodiments of the devices described herein may be similar to one or more of the catheters described in U.S. Pat. No. 6,401,719, issued Jun. 11, 2002, titled METHOD OF LIGATING HOLLOW ANATOMICAL STRUCTURES. In addition, the devices described herein may, in certain embodiments, be employed by practicing any of the methods disclosed in the above-mentioned U.S. Pat. No. 6,401,719, the entirety of which is hereby incorporated by reference herein and made a part of this specification.
The features of a system and method having electrode elements will now be described. The drawings, associated descriptions, and specific implementation are provided to illustrate embodiments of the invention and not to limit the scope of the invention. In addition, methods and functions described herein are not limited to any particular sequence, and the acts or states relating thereto can be performed in other sequences that are appropriate. For example, described acts or states may be performed in an order other than that specifically disclosed, or multiple acts or states may be combined in a single act or state.
In one embodiment, an energy source 702 comprises an alternating current (AC) source. In other embodiments, the energy source 702 comprises a direct current (DC) power supply, such as, for example, a battery, a capacitor, or other energy source. In some embodiments, the energy source 702 preferably comprises an RF generator powered by an AC or DC supply. The power source 702 may also incorporate a controller that, by use of a microprocessor, applies power using a temperature sensor located in the working portion of the catheter 700. For example, the controller may heat the tissue of a hollow anatomical structure to a set temperature. In an alternate embodiment, the user selects a constant power output of the energy source 702. For example, the user may manually adjust the power output relative to the temperature display from the temperature sensor in the working portion of the catheter 700.
In some embodiments, the catheter 710 has an internal lumen. The lumen preferably communicates between the distal tip and the proximal handle. The lumen may be used for fluid delivery such as saline, a venoconstrictor, sclerosant, high-impedance fluid, adhesive, hydrogel, or the like. In one embodiment, the catheter lumen can be used to apply a venoconstrictor prior to treatment with the electrode element. Application of a venoconstrictive agent to an interior portion of a hollow anatomical structure, e.g., a vein, can improve the apposition of the energy applying device to the structure wall. Venoconstrictive agents, when suitably applied, rely on the body's own physical reaction to the agent to contract and collapse around the therapeutic device.
The venoconstrictive agent preferably is easily applied over the target treatment length to enhance the performance of the device. The venoconstrictive agent preferably is non-toxic, well tolerated, effective in both sedated and non-sedated patients, and substantially free of adverse side effects. The venoconstrictive agent preferably is metabolized relatively quickly. Some embodiments comprise one or more of the following exemplary venoconstrictive agents: phenyl ephrine, high-concentration K+ solution, sumatriptan, dihydroergotamine, 5-hydroxytryptamine (or an equivalent that can bind to 5-HT1 receptors found in the saphenous vein), and other suitable agents.
In one application, the venoconstrictive agent is administered by direct injection to the interior of the hollow anatomical structure. In other applications, the venoconstrictive agent can be administered by superfusion to the exterior surface via injection, by systemic injection, or by other suitable methods. Application of the venoconstrictive agent may be made through the energy delivering device (e.g., the catheter 710), through another specialized delivery device, or through a nonspecialized delivery device. In some embodiments, occlusive methods, e.g., manual compression surrounding the area of interest, the use of a balloon, insertion of bioabsorbable occlusive elements or adhesives, can be used to locally isolate the venoconstrictive agent.
External physical and/or manual compression can also improve the apposition of the energy applying device to the structure wall. Compression methods can include external mechanical means to achieve compression, such as, for example, tumescent anesthesia, manual compression, vessel collapsing mechanisms that include spreadable opposed elements, reciprocating jaw mechanisms having penetrating elements, and devices for applying negative pressure to collapse the blood vessel.
Reducing the intra-luminal diameter of the vein can decrease the distance between the vein wall and the energy delivering device to increase the efficiency and uniformity of energy delivery to the vein wall. The vein can then be treated with the RF electrode element to further shrink the vein.
Upon completion of treatment, a hydrogel may be exuded from the distal catheter end allowing for complete vessel occlusion. For example, the hydrogel may be biocompatible or bioresorbable. In other embodiments, the hydrogel may be displaced by the constriction of the hollow anatomical structure resulting from the thermal injury response which results in substantially complete occlusion. In those sections of the hollow anatomical structure in which the material has not completely compressed, it can be resorbed by the body naturally. In yet other embodiments, the lumen may also accommodate a guide wire for catheter placement.
Some embodiments comprise a multi-ball configuration employed with or without a multiplexing process. For example,
In some embodiments, one or more electrode elements can be temperature controlled by having a temperature sensor as shown in
Alternatively, in one embodiment having multiple electrode elements, a temperature sensor is located on the most distal electrode. For example, the most distal electrode may be used for the initial treatment profile, and the successive electrode pairs may use the same and/or a predetermined energy-time profile.
In one embodiment, a method of use of the RF electrode element system 760, which is similar to the system described with reference to
Each tissue section adjacent to an electrode preferably is kept at the treatment temperature by cycling through the electrode sequence within a defined time. With reference to
In one embodiment, the electrode elements 760 through 768 are sequentially energized for a dwell time of 0.2 seconds. In the example shown, three electrode elements are powered at a time. The table in
In one embodiment, to avoid overcooling of a particular electrode element, the cycle time for the 8 active electrodes is of a short duration and/or the total number of electrode elements is limited. That is, in one embodiment, an electrode element may be re-energized before substantial cooling takes place. In addition, in one embodiment, to increase the treatment zone, the catheter may comprise multiple treatment zones, such as, for example, groups of eight electrode elements, as is shown in
Alternatively, at least one of the eight active electrode elements is energized to treat the hollow anatomical structure until treatment is complete. Then, the next active electrode element(s) apply a similar treatment time, and so on moving along the treatment zone. For the eight active electrode elements illustrated in
In other embodiments, alternate treatment cycles may be used. For example, active electrode elements 761 and 762 may concurrently treat the hollow anatomical structure for 40 seconds. Then, active electrode elements 763 and 764 apply a similar treatment, and so forth through active electrode elements 767 and 768 to complete the cycle.
In one embodiment, the catheter 780 is placed in the hollow anatomical structure, and then the balloon 782 is inflated through the internal ports. Once the balloon is inflated and in apposition to the vein wall, the fluid ports 784 preferably clear the treatment zone of the hollow anatomical structure of native fluid, such as blood, distal to the balloon 782, by injecting displacing fluid, such as, for example, saline. In one embodiment, the displacing fluid is followed by another injection of a venoconstrictor, which reduces the hollow anatomical structure lumen size prior to treatment. By temporarily reducing the hollow anatomical structure's size, the treatment time used for the active electrode elements 752 is reduced, thereby resulting in a shorter, safer and more effective treatment. Additionally, in one embodiment, constricting the hollow anatomical structure exsanguinates it of blood, enhancing the functionality of the device by reducing coagulum formation and promoting a better long-term efficacy by reducing the thrombotic occlusion.
In another embodiment, the device has a balloon at each end of the electrode set. The proximal balloon is inflated. A displacing fluid (as discussed above) is delivered using the fluid ports 784. The distal balloon preferably is partially inflated prior to fluid delivery and then fully inflated after fluid delivery to help isolate displacing fluid within that section of the hollow anatomical structure.
With reference to
In some embodiments, one or more electrode splines comprise one or more electrode elements. In one embodiment, a bipolar device comprises a plurality of electrodes on one or more splines. In another embodiment, a bipolar device has a plurality of splines having opposite polarities. In one embodiment, the electrode sets of each spline preferably are staggered relative to one another to form a checkerboard-like pattern. The checkerboard-like pattern preferably limits the likelihood that the electrodes will contact each other in the collapsed configuration. The exposed electrode portions preferably are positioned on the outer surface or face of the spline to contact a vein wall.
The device is designed to collapse by use of an outer sheath, which in
The self-adjusting splines preferably allow an appropriate amount of expansion for apposition to the tissue, while adjusting axially to bends or curves in the hollow anatomical structure. As the hollow anatomical structure is heated during treatment, the lumen preferably constricts and/or shrinks. The spline set preferably adjusts and collapses concurrently with the hollow anatomical structure. This same characteristic also gives the device of
Alternatively, the device comprises a stylet wire attached to the distal tip and placed axially and internally to the catheter in order to collapse and expand the pre-shaped splines. In this embodiment, the splines may be manually collapsed during treatment to duplicate the collapse or lumenal reduction of the hollow anatomical structure.
In some embodiments, each spline 802 is made of a spring type material such as Nitinol®. Other nickel based spring alloys, stainless spring alloys, 17-7 stainless, Carpenter 455 type stainless, or other non ferrous alloys such as beryllium copper can also be used. A temperature sensor can also be attached to one or more splines for temperature controlled energy delivery. Each spline 802 thus comprises a conductor which is covered in insulation over most of its length. To form one or more electrodes the insulation is skived away from portion(s) of the outward-facing surface of the spline(s) to selectively expose the underlying conductor.
In the embodiment illustrated in
As discussed above with respect to the fixed diameter electrode element systems, spline electrode elements, when individually wired for power, may be used in conjunction with a multiplexing process. Such an embodiment allows for the sequential or “cascading” heating of specific active electrode element subsets of the spline set. This may involve energizing at least one spline for a specific dwell time and then cascading axially or moving to the next adjacent spline(s) or electrode element(s) until the end spline or electrode element is reached. The cycle is then repeated until the complete treatment time is reached. Multiplexing can be used with monopolar or bipolar configurations of electrode element subsets. For a monopolar mode, a ground pad or virtual electrode is used in conjunction with active spline electrodes powered by the multiplexer. For a bipolar mode, adjacent electrodes on each spline are powered for treatment along each spline. In another embodiment, adjacent splines are bipolar so that spline pairs treat the vein along the spline length. In one embodiment, an active spline and two return splines are powered to treat the hollow anatomical structure.
A balloon can also be used to expand and collapse the electrode elements. The balloon preferably displaces blood from lumen being treated and can reduce the amount of coagulum build-up on the inside of the heating element. Minimizing coagulum build-up during the collapse and removal of the device is advantageous. In one embodiment, the balloon occludes the vessel, impairing blood flow and subsequent coagulum build-up to facilitate device removal. The balloon can act as a support structure for the outer electrodes to enhance vein wall apposition.
A temperature sensor can be placed on the distal end of the cantilevered spline electrode. In some embodiments, the sensor can be used with the RF power controller described above. The temperature sensor preferably is placed proximal to the treatment zone. In some embodiments the device is used such that the electrodes move or are ‘pulled back’ during treatment. Using multiple electrode sets preferably reduces the treatment time required. In other embodiments, the device is used in a stationary manner and subsequently moved to another section of the hollow anatomical structure for another treatment.
The embodiments illustrated in
With reference to
One or more temperature sensors can be placed on the distal end of the cantilevered spline electrodes. The device of the illustrated embodiment can be used with an RF power controller similar to that described above. The temperature sensor preferably is placed proximal to the treatment zone. The device can be used such that the device-electrodes move during treatment. Using multiple electrode sets preferably reduces the treatment time.
Another embodiment of a device 950 shown in
In one embodiment, each loop preferably is individually erectable or powered to match varying hollow anatomical structure diameters providing tailored treatment parameters. In one embodiment, all loops can be of the same length/diameter and can be actuated simultaneously.
The loop 955 may comprise an electrode element similar to the initial embodiment of
In one embodiment, the active electrodes are bipolar (e.g., comprising a positive and negative pain) on the loop itself. Each loop is used to treat a section of the vein. The number of loops expanded determines the treatment length enabling the device to be adjusted to provide a variable treatment length. In some embodiments, the device is moved and newly placed to treat the adjacent vein wall relative to the initial treatment.
In one embodiment, the foam is all open celled. In another embodiment, portions of the foam are open-celled. Open celled foam allows electrically conductive fluids, such as saline, to flow through it. The conductive fluid is used as a virtual electrode to contact the vein wall.
The foam component preferably has portions that are not open-celled in order to control or direct the conductive fluid flow. This is accomplished by using closed-cell foam or giving the foam surface a skin, which creates a fluid barrier.
This skived window 1052 creates an electrode from the exposed wire section and places it in contact with the vein wall only. The window creates a skived electrode similar to the checkerboard device electrode, however the individual braid wires 1054 are helically wound in the braid pattern and create a diamond pattern of electrodes. The braid electrode pattern is in apposition to the vein wall and is conformable before and during treatment.
The embodiment 1060 of
In one embodiment, the braid wire is sleeved in polyimide to isolate the wires from each other where they overlap as well as to create the skived electrode. The braid component can be created using standard braiding technology. Alternatively, a single wire may be woven into the braid component. The method is relevant for the overall resistance or impedance of the device for the energy source.
The proximal and distal ends of the braid 1066 component are captured in a two-part crimp sleeve, 1069 and 1071, in order to anchor the ends to the catheter tube 1070 and stylet 1067. The braid 1066 in this embodiment is expanded by the use of the catheter stylet 1067, which runs the internal axial length of the catheter, from the distal tip 1071 to the proximal handle (not shown). The proximal end of the stylet passes through a Touhy Borst type fitting on the catheter handle and in turn is a handle for stylet manipulation. In this case, pushing the stylet distally collapses the braid (illustrated in
In the embodiment of the invention illustrated in
It should be noted that the typical silicone extrusion may expand axially and radially when inflated. This causes the balloon to become “S” shaped for a set axial length of tubing, thus causing the braid to have non-uniform tissue apposition with the hollow anatomical structure. To compensate for this issue, the extrusion 1068 may be pre stretched axially just prior to anchoring on the catheter tubing to the stylet component 1067. The stretched tube may then expand radially with little to no axial expansion, depending on the amount of pre-stretch achieved. The balloon may be used to occlude the vessel to impair blood flow and to remove blood from the braid portion of the catheter. This creates a static fluid volume and makes the heat treatment more efficient. Also, the balloon promotes braid apposition with the hollow anatomical structure. In other embodiments, the balloon is at least partially expanded and contracted through expansion and compression of the ends 1081, 1084.
In one embodiment, a temperature sensor 1072 is attached to the braid wire along its axial length. The sensor 1072 may be used for temperature control during the application of energy for the controller. Although the sensor 1072 is shown attached near the proximal end of the braid wire, the sensor 1072 may be located along other portions of the braid wire. In addition, more than one sensor may be used.
In another embodiment, the balloon is a separate device from the braid device. For example, the balloon device may fit within the lumen of the braid device, and the tips of both devices may connect and anchor to one another. For example, the anchor mechanism may include a set of male and female threads appropriately sized. Alternatively, the device tips may be anchored together by use of axially aligned holes in both tips through which a wire is placed and tied off. Alternatively, the tips may be designed with a spring ball detent to anchor the tips together. Alternatively, strong magnets of opposite polarity may be used to locate the tips and hold them together.
As discussed above for the fixed diameter electrode element, the skived electrode wires, when individually wired for power, can be used in conjunction with the multiplexing process. This allows the heating of specific active electrode element subsets of the braid wire set. In one embodiment, at least one braid wire is energized for a specific dwell time and cascades or moves to the next braid wire until the end braid wire electrode set is reached. The cycle is then repeated until the complete treatment time is reached. The multiplexing can be used for monopolar or bipolar configurations of braid wire electrode sets. For a monopolar mode, a ground pad preferably is used in conjunction with active braid wire electrodes powered by the multiplexer. For a bipolar mode, adjacent braid wire electrode sets are powered for treatment. Alternatively, adjacent braid wires can be bipolar so that the pairs treat the vein along the braid length. Alternatively, one active braid wire and the two adjacent return braid wires can be powered to treat the vein wall.
Alternatively, the electrode set can be collapsed to a smaller diameter by moving the proximal end of the spline set axially in a proximal direction. A pull wire can be used to move the proximal end.
In another embodiment the proximal end is anchored and the electrode set is collapsed or expanded distally in the axial direction. A sheath can be used to expand or contract the electrode set.
In some embodiments, the distal portion of the catheter is collapsible to allow diametrical reduction of the hollow anatomical structure towards the catheter shaft. As the hollow anatomical structure is reduced, the distal catheter portion moves with respect to the catheter shaft in a radially collapsing direction. This movement preferably is monitored and/or conveyed to the handle to signal the end of treatment. In some embodiments, a pre-set axial migration of the distal portion is correlated to a specific lumenal reduction.
Except as further described herein, any of the catheters and/or devices or components of these catheters or devices disclosed in
The catheter shaft 1210 can be comprised of a biocompatible material preferably having a low coefficient of friction, such as polyimide, Teflon®, Hytrel® or other suitable material. The catheter shaft can be sized to fit within a hollow anatomical structure (HAS) between 6 and 8 French, which corresponds to a diameter of between 2.0 mm (0.08 in) and 2.7 mm (0.10 in), or other sizes as appropriate. The catheter shaft 1210 is used to maneuver the distal portion of the catheter during placement.
The retractable sheath 1216 exposes the distal portion of the device that applies energy to the HAS. The sheath can be employed to protect the device during placement, facilitate introduction of the device and/or adjust the exposed axial length for a desired treatment length. The sheath can be made from a biocompatible material preferably having a low coefficient of friction, such as polyimide, Teflon®, Hytrel® or other suitable material.
The distal portion of the device transfers electrical energy to the HAS for treatment. This portion may have a heating element that directly heats the HAS through heat conduction from the catheter shaft to the wall tissue. This portion may also incorporate a set of electrodes that deliver RF energy to the HAS and thereby generate heat within the HAS. This energy can be delivered up to a predetermined temperature or power level.
An atraumatic tip 1215 can be attached to the distal-most catheter end. The tip facilitates manipulation of the catheter through the HAS. The tip is preferably tapered inward at its distal end or is “nosecone” shaped, however, it can have other shapes that facilitate tracking of the catheter over a guide wire and through the bends and ostia in the vascular system. The nosecone-shaped tip can, for example, be fabricated from a polymer having a soft durometer. In some embodiments, the tip can be fabricated from polymers having durometers between about 60 and about 90 Shore A. In other embodiments, the tip can be fabricated from polymers with durometers between about 70 and about 80 Shore A, and in one preferred embodiment, a material with a durometer of about 70 Shore A is used.
A sensor 1211 can be attached to the exterior of the distal catheter shaft; this sensor can sense values pertinent to measuring the treatment's progress, such as temperature, impedance, or other pertinent treatment parameters. A single sensor 1211 is shown as part of the heating element; there can also be multiple sensors placed along the axial catheter length. The parameter measured will typically be that of the HAS tissue itself. The energy system 1218 can be employed to monitor the individual sensors and use the multiple inputs for feedback. The controller can be employed to monitor for high or low signals, and the microprocessor can be employed to determine the energy output accordingly. This control feedback mechanism may facilitate a more appropriate amount of energy to effectively and safely treat the HAS.
The handle houses an open port 1212 that directly communicates with an inner lumen extending the entire catheter length.
The treatment area of the HAS can also be flushed with a fluid such as saline through the inner lumen 1217 in order to evacuate blood from the treatment area of the HAS so as to prevent the formation of coagulum and subsequent thrombosis.
When the energy delivery method is an RF-based system, the use of a dielectric fluid (e.g., disposed within or around the HAS) can minimize unintended heating effects away from the treatment area. The dielectric fluid prevents the current of RF energy from flowing away from the HAS, instead it concentrates the energy delivered to the intended target. Any suitable dielectric fluid can be used as desired, for example dextrose is often used as a dielectric fluid in medical treatment contexts.
Alternative endolumenal implementations of fluid that can be delivered through the inner lumen 1217 might include drug therapies that promote fibrotic growth post endothelial layer destruction, such as TGF (Transforming Growth Factor) which is widely known to promote fibrotic reactions.
The inner lumen 1217 may also allow for the delivery of sclerosants to the interior of the HAS through an outlet at or near the distal end. Sclerosants typically denude the endothelial layer to damage and scar the inner HAS and further facilitate treatment of the HAS together with electrical energy delivery. Sclerosants, such as Polidocanol, hypertonic saline and Sclerodex or other chemical solutions with appropriate toxicity to endothelial cells are widely known in the art.
Finally, a guidewire can also be introduced through the inner lumen 1217 to facilitate catheter navigation to the desired treatment site. The guidewire is advanced to the treatment site prior to catheter advancement; once in place, the catheter is advanced over the guidewire to the treatment site.
The handle 1214 also houses an electrical connection that connects the energy system 1218 to a single or plurality of leads traveling down the catheter shaft. These leads may transfer direct thermal heat, or they may be switched as desired to operate in either a bipolar or a monopolar RF-based configuration. The number of leads can be dependent on the size or diameter of the HAS to be treated; larger vessels may require more leads to ensure proper current density and/or heat distribution.
The energy source 1223 is typically an AC (alternating current) power supply like an RF generator, or a DC (direct current) power supply. The DC power source may also be disposable in form such as a battery. Alternate energy sources may also comprise a laser, microwave, ultrasound, high-intensity ultrasound or other source.
The controller 1220, receives data from the feedback mechanism 1221 and modifies the energy delivery accordingly. The feedback mechanism may receive data from the sensor 1211, for example, and the controller may modify the energy source to supply heat to the HAS at a pre-set parameter. In an alternate embodiment, the user can select a constant power output; the user can then manually adjust the power output relative to the visual output 1222 from the sensor 1211 located at the working portion of the catheter.
The microprocessor 1219 works in conjunction with the controller to provide the algorithm by which the feedback data is processed.
The visual output 1222 can be employed to provide visual verification of critical values obtained during treatment of the HAS.
Alternatively, a softer distal tube section could be used which would be more flexible. In this configuration shown in
In another embodiment shown in
The ribbon elements 1240 can be made of an electrically-resistive material, such as nickel chromium, copper, stainless-steel, Nitinol®, Alumel® or other suitable materials, that heat when an energy source is applied. This mode of energy transfer would be direct heat conduction to the HAS tissue. The relative resistance or impedance of the resistive element is designed to be optimized for the energy source 1223. The resistive element will depend on the catheter diameter, the energy required, and the energy source requirements.
The ribbon elements 1240 and catheter shaft 1210 can also be used as electrodes to facilitate an RF-based treatment. In this embodiment, the ribbon elements 1240 would be made of a conductive material, such as those already discussed in the previous paragraph. In one scenario, the ribbon elements 1240 could be positively charged, and the catheter shaft could be negatively charged. In a second scenario, one of the ribbon elements could be positively charged, and the other ribbon element could be negatively charged. In a third scenario, both ribbon elements and the catheter shaft could both be positively charged to facilitate a monopolar RF-based treatment.
An alternate embodiment is shown in
In another embodiment, as shown in
To ensure even more complete HAS contact, other means to facilitate HAS wall contact may be applied in the form of tumescent infiltration, exterior manual compression, Trendelenburg positioning, and/or the use of veno-constrictive agents. For example,
In any of the device embodiments already discussed, the distal portion of the catheter may be collapsible in nature to allow lumenal reduction of the HAS towards the catheter shaft during energy application. As this lumenal reduction occurs, the distal end may move axially, in the proximal direction. Since reduction in HAS diameter typically signals successful application of energy, this axial movement could be monitored and/or conveyed to the handle signaling the end of treatment. In other words, a pre-set axial migration of the distal device portion could be correlated to a specific lumenal reduction. A signal capturing this movement could also be conveyed directly to the energy system as a feedback mechanism to the microprocessor to signal end of treatment to the energy source. The energy source could then stop delivering energy and the visual output could indicate successful and/or treatment end.
In one embodiment, a distal end of an HAS conforming device can be made of a shape-memory material, such as a nickel-titanium alloy. Such a device can be shape set and heat treated such that the device assumes a contracted shape when the material is below a pre-determined transition temperature, and assumes an expanded shape when the material is raised above the transition temperature. In some embodiments, the material can be selected and treated such that the transition temperature is above a patient's normal body temperature, but below an operating temperature of the device. In the case of a resistance-heated device, the temperature of the distal section can be controlled directly.
The first step in facilitating complete vein wall conformance is to introduce the device to the HAS. Once the device is placed in the desired location within the HAS, the device is deployed causing HAS conformance. If applicable and practical, the external compartment is then infiltrated with tumescent agent(s), and externally-placed manual compression is applied directly down onto the HAS. These steps help to promote a more effective treatment by removing HAS conformance inconsistencies due to vessel variability. Likewise, the additional measures of veno-constrictive agents and/or Trendelenburg positioning may be used.
Except as further described herein, any of the catheters disclosed in
Although invention(s) have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the invention(s) extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention(s) and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the disclosed invention(s) should not be limited by the particular embodiments described above, but should be determined only by a fair reading of the claims that follow.