Patent Application
20100160906
The present application relates generally to medical treatment devices, such as devices that treat lung diseases by applying energy to airways to reduce the resistance to airflow in the airways.
Asthma is a disease that makes it difficult to breathe and in many cases can be debilitating. Asthma is generally manifested by (a) bronchoconstriction, (b) excessive mucus production, and/or (c) inflammation and swelling of airways that cause widespread but variable airflow obstructions. Asthma can be a chronic disorder often characterized by persistent airway inflammation, but asthma can be further characterized by acute episodes of additional airway narrowing via contraction of hyper-responsive airway smooth muscle tissue.
Conventional pharmacological approaches for managing asthma include (a) administering anti-inflammatories and long-acting bronchodilators for long-term control, and/or (b) administering short-acting bronchodilators for management of acute episodes. Both of these pharmacological approaches generally require repeated use of the prescribed drugs at regular intervals throughout long periods of time. However, high doses of corticosteroid anti-inflammatory drugs can have serious side effects that require careful management, and some patients are resistant to steroid treatment even at high doses. As such, effective patient compliance with pharmacologic management and avoiding stimuli that trigger asthma are common barriers to successfully managing asthma.
Asthmatx, Inc. has developed new asthma treatments that involve applying energy to alter properties of the smooth muscle tissue or other tissue (e.g., nerves, mucus glands, epithelium, blood vessels, etc.) of airways in a lung of a patient. Several embodiments of methods and apparatus related to such treatments are disclosed in commonly assigned U.S. Pat. Nos. 6,411,852, 6,488,673, 6,634,363, 7,027,869, 7,104,987 and 7,425,212; and U.S. Patent Application Publication Nos. US 2005/0010270 and US 2006/0247746, all of which are incorporated by reference herein in their entirety.
Many embodiments of the foregoing asthma treatments that apply energy to tissue of the airways use catheters that can be passed (e.g., navigated) through the tortuous passageways defined by the lung airways.
One challenge of delivering energy to the airways in the lung is that it may take three sessions of 30-60 minutes each to treat a substantial portion of the lungs of a patient (e.g., upper and lower lobes). The three treatment sessions are usually performed on separate days, so it is also desirable to reduce the time necessary for such treatments. One factor affecting the treatment time is the length or width of the electrodes that contact the airway tissue. Another factor affecting treatment time is the loss of energy to surrounding tissue when monopolar configurations are employed.
Typical monopolar energy delivery devices require about 10 second activation time periods at approximately 65° C. to sufficiently treat target tissue and have small, short electrodes that limit the size of the contact area to reduce or mitigate non-uniformities of the current density in the tissue at the electrode. More specifically, the difference between the current density in the tissue at an edge of an electrode and the center of the electrode increases with increasing electrode dimensions (e.g., electrode length) due in part to tissue resistivity characteristics. The current density in the tissue proximate to the edges of a large, long electrode is accordingly significantly higher than the current density in the tissue at the center of the long electrode. This is known as the “edge effect,” and it is generally undesirable because the higher current densities at the edges or ends of the long electrode (or several short electrodes axially spaced and effectively acting as one long conductive area) may ablate and/or otherwise affect the airway tissue in an undesirable manner.
Current monopolar electrode configurations are accordingly limited to relatively small electrodes (e.g., 3-5 mm long) that exhibit acceptable edge effect non-uniformities. Small electrodes, however, treat corresponding small regions of tissue. Accordingly, small electrodes are advanced axially along airways in a large number of small increments to treat long segments of airways throughout the lung of the patient. As a result, small electrodes require longer and/or more treatment sessions to treat a patient and may result in over/under treatment of long segments due to repeated re-positioning.
Aspects of the present disclosure are directed to devices, systems, and methods for controlling the delivery of energy to tissue within a body cavity. Several examples of such systems have an energy delivery device configured to control the current density in tissue along an extended length. In particular, bipolar energy delivery devices do not exhibit edge effects, and as such efficiency does not decline with electrode length. Further, bipolar configurations provide faster, more efficient treatment because energy is concentrated in the target tissue resulting in more effective energy delivery. Thus, several embodiments of systems in accordance with this disclosure have relatively larger or longer conductive areas that can treat large cross-sectional areas of tissue within shorter activation time periods to reduce the number of treatment sites and cycles compared to shorter or otherwise smaller monopolar electrodes. Accordingly, shorter and/or fewer treatment sessions are needed to treat a patient and improved treatment consistency is achieved.
Specific examples of the system include an energy delivery device having an elongated member and an energy delivery unit at a distal portion of the elongated member. The energy delivery unit can include an inflatable or expandable, compliant member (e.g., a balloon) and one or more flexible, elongatable conductive elements or traces on an outer surface of the inflatable member. The flexible conductive elements can be composed of an electrically conductive, elastic material that stretches with the inflatable member without significant loss of conductivity. In this way, the flexible conductive element(s) effectively function as electrodes, while being simpler and less expensive to manufacture. The flexible conductive elements can have varying sizes, shapes, physical properties, numbers, thickness, spacing, distribution and/or densities. For example, the flexible conductive elements may be composed of conductive inks, polymers, or other suitable materials. The conductive elements can be disposed on the corresponding inflatable member using a variety of different processes. The flexible conductive elements may also be composed of an inelastic material (e.g., wire) configured to longitudinally expand and contract with the inflatable member.
Specific details of several embodiments of treatment devices, systems, and methods for delivering energy to passageways in a patient are described below with respect to delivering radio frequency energy to airways in a lung of a patient to treat asthma. Other embodiments of the technology, however, can deliver other energy modalities to lung airways or other tissues (e.g., body cavities, nerves, glands, skin, etc.) or passageways (e.g., blood vessel) for treating other indications. For example, the system can be configured to deliver thermal (resistive and/or infrared), laser, microwave, ultrasonic (e.g., HIFU), cryo-ablation, mechanical or other types of energy modalities to tissue. Moreover, several other embodiments of the invention can have different configurations, components, or procedures than those described in this section. As such, several of the details set forth below are provided to describe the following examples in a manner sufficient to enable a person skilled in the relevant art to practice, make and use the described examples without undue experimentation. Several of the details and advantages described below, however, may not be necessary to practice certain embodiments of the technology. Additionally, the technology may include other embodiments and methods that are within the scope of the claims but are not described in detail. Moreover, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more embodiments of the technology.
The energy delivery device 204 is an example of a treatment device for treating asthma or other indications associated with passageways in a human. The embodiment of the energy delivery device 204 illustrated in
Several embodiments of the elongated body 236 are flexible catheters configured to slide through the working lumen of an access device (e.g., bronchoscope; not shown in
The energy delivery unit 242 can have an inflatable member 260 movable between a retracted and an expanded configuration and one or more flexible conductive elements 250 configured to deliver energy to the tissue of an airway, passageway, or other body cavity in the patient. The inflatable member 260, for example, can be configured to contact the passageway and present the conductive elements 250 to the passageway. For example, the inflatable member 260 may comprise a compliant balloon or another type of member that is inflatable, self-expandable, and/or mechanically actuatable. The inflatable member may expand anywhere from two to three times from its initial diameter so as to treat airways in a range from 2-6 mm and 2-8 mm, respectively. The conductive elements 250 can be flexible or expandable metal bands, metallic arrays, traces, electrode segments, or other electrically conductive mediums or elements that can conduct sufficient electrical current in applications that deliver RF energy or other electrical energy. Further details describing various embodiments of suitable energy delivery units 242 are described below with reference to
The handle 244 is configured so that a single operator can hold an access device (e.g., a bronchoscope) in one hand (e.g., a first hand) and use the other hand (e.g., a second hand) to (a) advance the elongated body 236 through a working lumen of the access device until the energy delivery unit 242 projects beyond the distal end of the access device and is positioned at a desired target site and (b) inflate or otherwise expand the inflatable member 260 to move the conductive elements 250 outwardly until they contact the sidewall of an airway passage while the catheter is held in place relative to the access device with the same second hand. The same operator can also operate the switch 230 of the power/control unit 202 such that the entire procedure can be performed by a single person. The handle 244 is described in greater detail in U.S. patent application Ser. No. 11/777,225, which is incorporated by reference herein in its entirety.
In several embodiments of the system, the controller 208 includes a processor that is generally configured to accept information from the system 200 and components associated with the system 200. The processor can process the information according to various algorithms to produce control signals for controlling the energy generator and/or produce information signals. The information signals produced by the processor may be directed to visual indicators, a digital display, or an audio tone generator of the user interface to inform the user of the system status, component status, procedure status, or any other useful information monitored by the system. The processor of the controller 208 may be a digital IC processor, analog processor, or any other suitable logic or control system that carries out the control algorithms.
Specific embodiments of systems that control power output to the energy delivery device 204 are described in U.S. Pat. No. 7,104,987, U.S. Patent Application Publication No. US 2006/0247746, and U.S. patent application Ser. No. 12/179,301, which are incorporated by reference herein in their entirety. The system 200 may deliver energy to target sites via the energy delivery device 204 in a variety of treatment patterns. Further details with respect to other designs and types of treatment devices, examples of energy, and/or examples of treatment patterns may be found in commonly-assigned U.S. Pat. No. 6,411,852.
The inflatable member 260 comprises a non-conductive, non-porous, compliant balloon. The inflatable member 260 can be composed of a material such as silicone, a low durometer polymer (e.g., urethane), or another suitable biocompatible material that allows the inflatable member 260 to expand (e.g., approximately 2-3 times) from its original diameter. In the illustrated embodiment, the energy delivery unit 242 includes two flexible, elongatable conductive elements 250a and 250b carried by an outer surface of the inflatable member 260. The conductive elements 250a and 250b of this embodiment are composed of an elastic material that stretches with the inflatable member 260 (such as in the expanded configuration of
In operation, the energy delivery unit 242 is inserted into the passageway 300 in the retracted configuration (as shown in
After the inflatable member 260 is expanded, the power control unit 202 (
One feature of the bipolar energy delivery unit 242 described above is that the depth and uniformity of the treatment area can be increased as compared with conventional monopolar energy delivery devices. For example, the bipolar design of the energy delivery unit 242 allows the full circumference of the passageway (e.g., airway) to be treated. Thus, the energy delivery unit 242 may provide a uniform or near uniform current density in tissue around the circumference and/or along a length of a bronchial airway or other passageway. In addition, more energy can be delivered to the passageway during each treatment session because the longitudinal coverage of the conductive elements 250a and 250b along the airway wall can be far greater than the 5 mm maximum length of monopolar electrodes (e.g., 5-10-15 mm) without the effectiveness of the conductive elements being hampered by edge effects. Accordingly, the total treatment time for a patient can be reduced. Moreover, less total energy is required than with conventional monopolar devices because the energy loss to the surrounding tissue is expected to be reduced as energy is concentrated in the treatment area. As such, activation time periods in bipolar mode can be reduced (e.g., 1-4 seconds at approximately 60-75° C.; 2-3 seconds at approximately 65-70° C.).
Another feature of the energy delivery unit 242 is that the spacing between the conductive elements 250a and 250b can be precisely controlled. For example, the depth of heating can be adjusted by varying the conductivity, width, and/or spacing of the conductive elements 250a and 250b on the surface of the inflatable member 260. This feature is expected to provide better control and enhance the ability to produce generally uniform treatment areas about the energy delivery unit 242.
Still another feature of the energy delivery unit 242 described above is that a range of airway sizes can be treated with a single design. For example, because the flexible conductive elements 250a and 250b can stretch or expand with the inflatable member 260, the energy delivery unit 242 can be used in airways having varying geometries. Accordingly, a single design can be used for treating airways having a wide range of sizes and/or shapes.
Referring first to
The conductive ink 400 and 410 may be applied to the inflatable member 260 using a pen, a silk screen process, a pad print process, a spraying process, an ink jet printing process, or other suitable techniques. In one embodiment, for example, the conductive ink 400 and 410 can be applied to the inflatable member 260 and cured while the inflatable member 260 is in an expanded position. In some situations, however, the conductive ink 400 and 410 may separate, tent, or crack when applied to the inflatable member 260 in a fully expanded position. Accordingly, in other embodiments, the inflatable member 260 can be expanded to an intermediate (or semi-expanded) position for application of the conductive ink 400 and 410. For example, if conductive ink 400 and 410 is being applied to an inflatable member 260 that has a diameter of approximately 2 mm in its retracted configuration (e.g.,
The conductive filler 404a-b in the conductive inks 400 and 410 changes in resistance when the corresponding inflatable member (e.g., inflatable member 260 of
In still other embodiments, the conductive inks 400 and/or 410 can include different features and/or have different configurations. For example, in one embodiment the individual elements of the conductive particles 404a-b may be aligned or at least approximately aligned to minimize the resistance of the corresponding conductive ink 400 and 410 when it is fully stretched. In another embodiment, the conductive ink 400 and 410 may be overloaded with the conductive particles 404a-b so that the resistance of the conductive ink 400 and 410 is greater when the conductive ink is in its initial, unstretched state than when the conductive ink 400 and 410 stretches as the inflatable member 260 is inflated.
The energy delivery units described above with reference to
The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology. Additionally, unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in a sense of “including, but not limited to.” Words using the singular or plural number also include the plural or singular number, respectively. When the claims use the word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
The foregoing specific embodiments of the disclosure have been described for the purposes of illustration, but various modifications may be made without deviating from the scope of the disclosure. For example, specific features or processes of the various examples described above can be combined to provide further examples. Aspects of the technology may accordingly be modified, if necessary, to employ treatment devices with a plurality of treatment units, thermally conductive devices with various configurations, and concepts of the various patents, applications, and publications incorporated by reference to provide yet further embodiments of the technology. These and other changes, therefore, can be made to the technology in light of the above detailed description. In general, in the following claims, the terms used should not be construed to limit the technology to the specific examples disclosed in the specification and the claims, but should be construed to include all embodiments in accordance with the claims. Accordingly, the technology is not limited by the disclosure, but instead its scope is to be determined entirely by the following claims.
The present application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/140,547, filed Dec. 23, 2008, the disclosure of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61140547 | Dec 2008 | US |
