US20090069797A1 - Bipolar devices for modification of airways by transfer of energy - Google Patents

Abstract

This relates to a device for treating lung disease, and more particularly, relates to a device for exchanging energy with airway tissue such as that found in the airways of human lungs. The exchange of energy with this airway tissue in the airways reduces the ability of the airways to constrict and/or reduces the resistance within the airway to the flow of air through the airway.

Description

• This is a Continuation-in-part application of U.S. application Ser. No. 09/296,040 filed Apr. 21, 1999, and of Continuation-in-part U.S. application Ser. No. 09/095,323 filed Jun. 10, 1998 both of which applications are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The invention relates to a device for treating lung disease, and more particularly, the invention relates to a device for transferring energy into airway tissue such as that found in the airways of human lungs. This includes heating and applying RF energy to the airway. In the airways of the lung, the transfer of energy into the airway tissue stiffens that tissue or reduces the ability of the airways to constrict. In general the treatment reduces the resistance to the flow of air through the airway.
• 2. Brief Description of the Related Art
• Asthma is a disease in which (i) bronchoconstriction, (ii) excessive mucus production, and (iii) inflammation and swelling of airways occur, causing widespread but variable airflow obstruction thereby making it difficult for the asthma sufferer to breathe. Asthma is a chronic disorder, primarily characterized by persistent airway inflammation. However, asthma is further characterized by acute episodes of additional airway narrowing via contraction of hyper-responsive airway smooth muscle.
• Asthma stimuli may be allergenic or non-allergenic. Examples of allergenic stimuli include pollen, pet dander, dust mites, bacterial or viral infection, mold, dust, or airborne pollutants; non-allergenic stimuli include exercise or exposure to cold, dry air.
• In asthma, chronic inflammatory processes in the airway play a central role. Many cells and cellular elements are involved in the inflammatory process, particularly mast cells, eosinophils T lymphocytes, neutrophils, epithelial cells, and even airway smooth muscle itself. The reactions of these cells result in an associated increase in the existing sensitivity and hyperresponsiveness of the airway smooth muscle cells that line the airways to the particular stimuli involved.
• The chronic nature of asthma can also lead to remodeling of the airway wall (i.e., structural changes such as thickening or edema) which can further affect the function of the airway wall and influence airway hyperresponsiveness. Other physiologic changes associated with asthma include excess mucus production, and if the asthma is severe, mucus plugging, as well as ongoing epithelial denudation and repair. Epithelial denudation exposes the underlying tissue to substances that would not normally come in contact with them, further reinforcing the cycle of cellular damage and inflammatory response.
• In susceptible individuals, asthma symptoms include recurrent episodes of shortness of breath (dyspnea), wheezing, chest tightness, and cough. Currently, asthma is managed by a combination of stimulus avoidance and pharmacology.
• Stimulus avoidance is accomplished via systematic identification and minimization of contact with each type of stimuli. It may, however, be impractical and not always helpful to avoid all potential stimuli.
• Asthma is managed pharmacologically by: (1) long term control through use of anti-inflammatories and long-acting bronchodilators and (2) short term management of acute exacerbations through use of short-acting bronchodilators. Both approaches require repeated and regular use of the prescribed drugs. High doses of corticosteroid anti-inflammatory drugs can have serious side effects that require careful management. In addition, some patients are resistant to steroid treatment. Patient compliance with pharmacologic management and stimulus avoidance is often a barrier to successful asthma management.
• Asthma is a serious disease with growing numbers of sufferers. Current management techniques are neither completely successful nor free from side effects.
• Accordingly, it would be desirable to provide an asthma treatment which improves airflow without the need for patient compliance.
• In addition to the airways of the lungs, other body conduits such as the esophagus, ureter, urethra, and coronary arteries, are also subject to periodic spasms that interfere with their normal function.
SUMMARY OF THE INVENTION
• The present invention relates to a device for treating airway tissue within the lungs by transfer of energy into the walls of the airway to reduce plugging of the airway, to prevent the airway from being able to constrict, to increase the inner airway diameter, or to reduce resistance to flow through the airway. The invention is particularly directed to the treatment of the airways in the lungs to reduce the effects of asthma and other lung disease. One variation of the invention includes the transfer of energy to the airway wall via the application of heat.
• The present invention provides devices to decrease airway responsiveness and airway resistance to flow which may augment or replace current management techniques. In accordance with one variation of the present invention, an energy transfer apparatus for treating conditions of the lungs by decreasing airway responsiveness includes transferring energy into an airway wall to alter the airway wall in such a manner that the responsiveness of the airway is reduced.
• In particular, the inventive device is an energy transfer apparatus which facilitates energy transfer with a mass of tissue within the airways of a lung. The inventive device is sized to enter the bronchus or bronchiole of a human lung to conduct energy transfer with the airway tissue therein. The inventive device may also be sized to fit within a bronchoscope. The bronchoscope may have a channel with a diameter of preferably 2 mm or less.
• A variation of the inventive device includes a flexible elongated body having a proximal portion and a distal portion with a lumen extending between the proximal and distal portions. The flexible elongated body may be of sufficient stiffness to pass through a seal of a working channel of a bronchoscope and allow operation of the device through the working channel seal. The device may include an expandable portion that is adjacent to a distal portion of the elongated body. The expandable portion has a first state, e.g., a size, and a second state where the second state is radially expanded in size from the elongated body. The device may include a temperature detecting element which is placed near to the expandable portion. The device also includes at least one energy transfer element at an exterior of the expandable portion, where the energy transfer elements are configured to contact the wall of the bronchus or bronchiole when the expanded portion is in an expanded state. The device may also include a deployment member that is configured to move the expandable portion between the first and second radially expanded states. The deployment member may extend between the expandable portion and the proximal portion of the elongated body. The inventive device may further include a distal tip located at a distal end of the apparatus. One variation of the inventive device includes an expandable portion that has a diameter of less than 15 mm when in a second expanded state.
• Another variation of the invention includes an expandable portion which includes pre-shaped tines. Such tines are configured to be in a first state within an elongated body and, when advanced out of the elongated body, to expand into a second expanded state. The tines may be connected to each other with an expanding element to prevent the tines from entering multiple airways at a bifurcation.
• Another variation of the invention includes an expandable portion comprised of a balloon. This variation of the invention may include the use of a fluid which may expand the balloon into the second state. Yet another variation of this invention includes the use of a heat generating element in the balloon which conducts heat to the fluid to heat an exterior of the balloon. In this variation, the exterior of the balloon serves as the energy transfer element.
• A further variation of the inventive device includes an expandable portion which comprises a plurality of legs which forms a basket. The legs of this variation may extend from a proximal joint that is found at an intersection of a distal portion of the elongated body to a distal joint that is adjacent to a distal tip. Each leg may have a center that is substantially parallel to the elongated body so that there is sufficient contact between the airway walls and the parallel portion of the leg. The center that is substantially parallel is usually referred to as the active region of the leg. The
• The legs of this variation may be spaced around a circumference of the elongated body to form a basket. The legs of this variation may have a circular cross section or a rectangular cross section, or other non-axisymmetric cross sections. The cross sections may be chosen to allow ready deployment from a first state to a second expanded state, while resisting out-of-plane bending which may distort the spacing of the legs or the contact of electrodes with the airway surface. One variation of the invention includes a basket in which the distance between the proximal and distal joint is less than 35 mm when the basket is not expanded. Another variation of this invention includes a basket that comprises four or five legs. In this case, the legs may be placed evenly around a circumference of the elongated body. In this case the legs may be found at intervals of 90 or 72 degrees. Other variations of the invention include devices having less than four legs or more than five legs. Another variation of this inventive device includes placing a temperature detecting element on one or on more legs. In this variation, the temperature of one leg may be monitored or the temperature of several legs may be independently monitored to control the energy delivery. In a further variation, multiple temperature sensing elements may be combined with independent control of energy to each leg. Both of these variations may also apply to a variation of the device having pre-shaped tines. The legs may be soldered or made to adhere using adhesives to the elongated body at the proximal and distal ends. Another variation of the invention includes a multi-lumen elongated body into which a portion of each leg is inserted. It is also contemplated that an elongated member may be reinforced via a reinforcing member. Such a reinforcing member may include a coiled or braided wire, polymeric insert, or any other similar reinforcing member.
• The energy transfer element of the invention may include an element that directly heats tissue by delivering current such as an RF based electrode. The RF electrode may be either bipolar or monopolar or a heated element that conductively heats tissue. In variations of the invention using RF energy, the frequency of the RF may be selected to be in the 400 kHz range or any other standard medical range used in electro-surgical applications.
• When the electrode directly heats the tissue, the heated element may use AC or DC current to resistively heat the element. RF energy may also be used to resistively heat the element. An indirect method of heating includes a resistively heated element that conducts heat to the expandable portion or directly to the airway. The invention may also include a combination of the types of electrodes mentioned above.
• In the variation of the invention in which the expandable portion comprises a basket, each of the energy transfer elements may be a RF electrode that is attached to each leg. The electrode may be fastened by a heat shrink fastener. In such a case, a temperature detecting element may be placed on the leg and underneath the fastener. A resistance heating element may be coiled around a portion of the leg. In this case, a temperature detecting element may be placed underneath the coil. Other examples of the energy transfer element include a polymeric heating element, an electrically conductive paint, or a printed flex circuit which are on a portion of the leg. Another variation employs the basket leg itself as either a RF electrode or a heated element. In such cases, the temperature sensing element may be attached directly to a basket leg by soldering, welding, adhesive bonding, or other means.
• Another variation of the invention includes a sheath slidably coupled to and exterior to the expandable portion. The expandable portion may be resilient and self-expand into the second state when no longer confined by the sheath. For example, the sheath may be withdrawn in a proximal direction or the expandable portion may be advanced out of the sheath.
• Yet another variation of the invention includes a deployment member comprising a handle adjacent to a proximal end of the elongated body. The elongated body may be slidably attached to the handle. The deployment member may also comprise a wire that extends from the handle through the lumen of the elongated body and is fixedly attached to the distal tip. This wire may also provide a current to the energy transfer members. The elongated body, the wire, and the distal tip may be slidably moveable in a distal and proximal direction. This variation of the deployment member may also include a stop configured to prevent distal movement of the wire beyond a deployment point. In this variation, beyond the deployment point, movement of the elongated body against the non-moving distal tip causes the expansion member to expand from a first state into a second expanded state.
• Another variation of the invention includes a deployment member comprising a sheath that covers the elongated member and expandable portion and a handle at a proximal end of the sheath. The sheath may be slidably attached to the handle while the elongated member is rigidly attached to the handle. A wire may extend from said handle to a distal tip through a lumen of the elongated member. The variation may include a first control member attached to the sheath and slidably attached to the handle where proximal movement of the first control member causes the sheath to retract on the elongated member and uncover the expandable portion. This variation may also include a second control member which is attached to the wire where proximal movement of the second control member causes the distal tip and the expandable portion to retract against the non-moving elongated member and causes the expandable portion to radially expand into a second state.
• Another variation of the invention includes a deployment member having force compensation or deflection limiting stops to prevent over-expansion of the expandable member when deployed within the body.
• A variation of the invention includes placing a sheath exterior to the elongated body and expandable portion such that the expandable portion is placed within the sheath in a first unexpanded state. When the expandable portion is no longer restrained by the sheath, the expandable portion expands into its second state. The invention may also include a control member moveably secured to the handle where the member is configured to advance the elongated body and the wire in the distal and proximal directions. Another variation of the invention includes a detent means for maintaining the elongated body distally of the deployment point. The control member may also be configured to frictionally maintain the elongated body distally of the deployment point. In these cases, the expandable portion will be in the second expanded state. Other variations of the inventive device may include use of levers, control wheels, or screw mechanisms in place of a control member.
• Another variation of the inventive device includes a distal tip that may be configured to prevent gouging of the airway tissue. The distal tip may have a redundant joint to prevent separation of the tip from the apparatus. The distal tip may also be sized to fit within a bronchoscope.
• Another variation of the invention includes a central wire extending from the distal tip to the proximal portion of the device. The wire may be configured to provide a current to the energy transfer elements. A temperature detecting element may also be attached to the wire.
• The inventive device may also be radiopaque or may have radiopaque elements.
• Another variation of the invention includes providing a steering member in the device to deflect the distal tip of the apparatus in a desired direction.
• Another variation of the invention includes placing a vision system on the apparatus. The vision system may include a fiber-optic cable or a CCD chip.
• Another variation of the invention includes providing a power supply configured to deliver energy through the energy transfer elements to the airway walls. The power supply may be configured to include a high temperature shut off or one which shuts down if a minimum temperature is not detected within a predetermined time or if a minimum temperature slope is not detected during a predetermined time.
• The invention further includes a kit comprising an energy transfer apparatus for facilitating energy transfer into a mass of airway tissue and a generator configured to delivery energy to the energy transfer apparatus. The kit may further include a bronchoscope.
• The invention further includes an energy transfer apparatus for facilitating energy transfer into a mass of airway tissue within a lung, the energy transfer apparatus having been rendered sterile for the purposes of prevention of infection of the lung.
• The invention further includes a modified lung configured to have an artificially altered airway within the lung, the airway being artificially altered by transfer of energy to the airway such that the airway has a reduced ability to constrict, an increased airway diameter, a increase in resistance to plugging, and a decrease in resistance to airflow.
• The present invention may be used for a treatment of asthma or other constriction or spasm of a bodily conduit by application of energy. The treatment reduces the ability or propensity of the airway to contract, reduces plugging of the airway, increases the inner airway diameter, and/or reduces resistance to flow through the airway.
BRIEF DESCRIPTION OF THE DRAWINGS
• The invention will now be described in greater detail with reference to the various embodiments illustrated in the accompanying drawings:
• FIG. 1 is a cross sectional view of a medium sized bronchus in a healthy patient.
• FIG. 2 is a cross sectional view of a bronchiole in a healthy patient.
• FIG. 3 is a cross sectional view of the bronchus ofFIG. 1 showing the remodeling and constriction occurring in an asthma patient.
• FIG. 4 is an illustration of the lungs being treated with a device according to the present invention.
• FIG. 5A is a partial side view of a variation of the inventive device having a plurality of wire shaped electrodes.
• FIG. 5B is a cross sectional side view of another variation of a device having a plurality of wire shaped electrodes with a deployment wire attached to a distal tip of the device.
• FIG. 5C shows a partial view of a variation of an elongated member of inventive device having a plurality of lumens for nesting the legs of the basket.
• FIGS. 5D-5I illustrate a variation of the invention and a deployment member for deploying the device.
• FIGS. 5J-5L illustrate examples of energy transfer elements of the device.
• FIG. 5M shows a partial view of a thermocouple attached to a basket leg.
• FIGS. 6A-6D illustrates distal joints of the invention.
• FIG. 6E illustrates a proximal joint of the invention.
• FIGS. 7A-7D illustrates a series and parallel wiring of legs of the basket.
• FIGS. 8A-8C illustrate examples of variable thicknesses of legs of the basket.
• FIGS. 9A-9D illustrate examples of a basket formed from a single sheet or piece of material.
• FIG. 10 is a side cross sectional view of a variation of the inventive device having a balloon with electrodes positioned exterior to the balloon.
• FIG. 11 is a partial side view of a variation of the inventive device having a balloon with heat generating elements positioned within the balloon for indirect heating of the tissue.
• FIG. 12 is cross sectional view of the inventive device with electrodes and pre-shaped tines as the expandable member.
• FIG. 13 is a cross sectional view of a variation of the inventive device with energy transfer elements positioned on expandable balloons.
• FIG. 14 is an illustration of a variation of the inventive device with electrodes positioned in grooves.
• FIG. 15 is an illustration of a variation of the inventive device with electrodes and a biasing element.
• FIG. 16 is an illustration of another variation of the inventive device having electrodes and a biasing element.
• FIG. 17 is a partial side view of a variation of the inventive device having electrodes exposed by cut away sections of an elongated member.
• FIG. 18 is a partial side view of the inventive device with electrodes positioned on a loop shaped member.
• FIG. 19 is a cross sectional view of a variation of the inventive device having a looped shaped electrode in an unexpanded position.
• FIG. 20 is a cross sectional view of the variation ofFIG. 19 with the looped shape electrode in an expanded position.
DETAILED DESCRIPTIONReducing the Ability of the Airway to Contract
• The inventive airway energy treatment may be used to reduce the ability of the airways to narrow or to reduce in diameter due to airway smooth muscle contraction. This treatment to reduce the ability of the smooth muscle to contract lessens the severity of an asthma attack. The reduction in the ability of smooth muscle to contract may be achieved by treating the smooth muscle itself or by treating other tissues which in turn influence smooth muscle contraction or the response of the airway to smooth muscle contraction. Treatment may also reduce airway responsiveness or the tendency of the airway to narrow or to constrict in response to a stimulus.
• The amount of smooth muscle surrounding the airway can be reduced by exposing the smooth muscle to energy which either kills the muscle cells or prevents these cells from replicating. The reduction in smooth muscle reduces the ability of the smooth muscle to contract and to narrow the airway during a spasm. The reduction in smooth muscle and surrounding tissue has the added potential benefit of increasing the caliber or diameter of the airways, reducing the resistance to airflow through the airways. In addition to use in debulking smooth muscle tissue to open up the airways, the device of the present invention may also be used for eliminating the smooth muscle altogether by thermally damaging or destroying it. The elimination of the smooth muscle prevents the hyper-reactive airways of an asthma patient from contracting or spasming, reducing or eliminating this asthma symptom.
• The ability of the airway to contract can also be altered by treatment of the smooth muscle in particular patterns. The smooth muscle is arranged around the airways in a generally helical pattern with pitch angles ranging from about −30 to about +30 degrees. Thus, the treatment of the smooth muscle by energy which is selectively delivered in an appropriate pattern interrupts or cuts through the helical pattern at a proper pitch and prevents the airway from constricting. This procedure of patterned application of energy eliminates contraction of the airways without completely eradicating smooth muscle and other airway tissue. A pattern for treatment may be chosen from a variety of patterns including longitudinal or axial stripes, circumferential bands, helical stripes, and the like as well as spot patterns having rectangular, elliptical, circular or other shapes. The size, number, and spacing of the treatment bands, stripes, or spots are chosen to provide a desired clinical effect of reduced airway responsiveness while limiting insult to the airway to a clinically acceptable level.
• The patterned treatment of the tissues surrounding the airways with energy provides various advantages. The careful selection of the portion of the airway to be treated allows desired results to be achieved while reducing the total healing load. Patterned treatment can also achieve desired results with decreased morbidity, preservation of epithelium, and preservation of a continuous or near continuous ciliated inner surface of the airway for mucociliary clearance. The pattern of treatment may also be chosen to achieve desired results while limiting total treatment area and/or the number of airways treated, thereby improving speed and ease of treatment.
• Application of energy to the tissue surrounding the airways also may be used to cause the DNA of the cells to become cross linked. The treated cells with cross linked DNA are incapable of replicating. Accordingly, over time, as the smooth muscle cells die, the total thickness of smooth muscle decreases because of the inability of the cells to replicate. The programmed cell death causing a reduction in the volume of tissue is called apoptosis. This treatment does not cause an immediate effect but causes shrinking of the smooth muscle and opening of the airway over time and substantially prevents re-growth. The application of energy to the walls of the airway may also be used to cause a cross linking of the DNA of the mucus gland cells thereby preventing them from replicating and reducing excess mucus plugging or production over time.
• The ability of the airways to contract may also be reduced by altering mechanical properties of the airway wall, such as by increasing stiffness of the wall or by increasing parenchymal tethering of the airway wall. Both of these methods increase the strength of the airway wall and opposes contraction and narrowing of the airway.
• There are several ways to increase the stiffness of the airway wall. One way to increase stiffness is to induce fibrosis or wound healing response by causing trauma to the airway wall. The trauma can be caused by delivery of therapeutic energy to the tissue in the airway wall or by mechanical insult to the tissue. The energy is preferably delivered in such a way that it minimizes or limits the intra-luminal thickening that can occur.
• Another way to increase the effective stiffness of the airway wall is by altering the submucosal folding of the airway upon narrowing. The submucosal layer is directly beneath the epithelium and its basement membrane and inside the airway smooth muscle. As an airway narrows, its perimeter remains relatively constant, with the mucosal layer folding upon itself. As the airway narrows further, the mucosal folds mechanically interfere with each other, effectively stiffening the airway. In asthmatic patients, the number of folds is fewer and the size of the folds is larger, and thus, the airway is free to narrow with less mechanical interference of mucosal folds than in a healthy patient. Thus, asthmatic patients have a decrease in airway stiffness and the airways have less resistance to narrowing.
• The mucosal folding in asthmatic patients can be improved by treatment of the airway in a manner which encourages folding. Preferably, a treatment will increase the number of folds and/or decrease the size of the folds in the mucosal layer. For example, treatment of the airway wall in a pattern such as longitudinal stripes can encourage greater number of smaller mucosal folds and increase airway stiffness.
• The mucosal folding can also be increased by encouraging a greater number of smaller folds by reducing the thickness of the submucosal layer. The decreased thickness of the submucosal layer may be achieved by application of energy which either reduces the number of cells in the submucosal layer or which prevents replication of the cells in the submucosal layer. A thinner submucosal layer will have an increased tendency to fold and increased mechanical stiffening caused by the folds.
• Another way to reduce the ability of the airways to contract is to improve parenchymal tethering. The parenchyma surrounds airways and includes the alveolus and tissue connected to and surrounding the outer portion of the airway wall. The parenchyma includes the alveolus and tissue connected to and surrounding the cartilage that supports the larger airways. In a healthy patient, the parenchyma provides a tissue network which connects to and helps to support the airway. Edema or accumulation of fluid in lung tissue in asthmatic patients is believed to decouple the airway from the parenchyma reducing the restraining force of the parenchyma which opposes airway constriction. Application of therapeutic energy can be used to treat the parenchyma to reduce edema and/or improve parenchymal tethering.
• In addition, the applied energy may be used to improve connection between the airway smooth muscle and submucosal layer to the surrounding cartilage, and to encourage wound healing, collagen deposition, and/or fibrosis in the tissue surrounding the airway to help support the airway and prevent airway contraction.
Increasing the Airway Diameter
• Airway diameter in asthmatic patients is reduced due to hypertrophy of the smooth muscle, chronic inflammation of the airway tissues, and general thickening of all parts of the airway wall. The overall airway diameter can be increased by a variety of techniques to improve the passage of air through the airways. Application of energy to the airway smooth muscle of an asthmatic patient can be used to debulk or reduce the volume of smooth muscle. This reduced volume of smooth muscle increases the airway diameter for improved air exchange.
• The airway diameter can also be increased by reducing inflammation and edema of the tissue surrounding the airway. Inflammation and edema (accumulation of fluid) of the airway occur in an asthmatic patient due to irritation. The inflammation and edema can be reduced by application of energy to stimulate wound healing and regenerate normal tissue. Healing of the epithelium or sections of the epithelium experiencing ongoing denudation and renewal allows regeneration of healthy epithelium with less associated airway inflammation. The less inflamed airway has an increased airway diameter both at a resting state and in constriction. The wound healing can also deposit collagen which improves parenchymal tethering.
• Inflammatory mediators released by tissue in the airway wall may serve as a stimulus for airway smooth muscle contraction. Smooth muscle contraction, inflammation, and edema can be reduced by a therapy which reduces the production and release of inflammatory mediators. Examples of inflammatory mediators are cytokines, chemokines, and histamine. The tissues which produce and release inflammatory mediators include airway smooth muscle, epithelium, and mast cells. Treatment of these structures with energy can reduce the ability of the airway structures to produce or release inflammatory mediators. The reduction in released inflammatory mediators will reduce chronic inflammation, thereby increasing the airway inner diameter, and may also reduce hyper-responsiveness of the airway smooth muscle.
• A further process for increasing the airway diameter is by denervation. A resting tone of smooth muscle is nerve regulated by release of catecholamines. Thus, by damaging or eliminating nerve tissue in the airways the resting tone of the smooth muscle will be reduced, and the airway diameter will be increased.
Reducing Plugging of the Airway
• Excess mucus production and mucus plugging are common problems during both acute asthma exacerbation and in chronic asthma management. Excess mucus in the airways increases the resistance to airflow through the airways by physically blocking all or part of the airway. Excess mucus may also contribute to increased numbers of leukocytes found in airways of asthmatic patients by trapping leukocytes. Thus, excess mucus can increase chronic inflammation of the airways.
• One type of asthma therapy involves treatment of the airways with energy to target and reduce the amount mucus producing cells and glands and to reduce the effectiveness of the remaining mucus producing cells and glands. The treatment can eliminate all or a portion of the mucus producing cells and glands, can prevent the cells from replicating or can inhibit their ability to secrete mucus. This treatment will have both chronic benefits in increasing airflow through the airways and will lessen the severity of acute exacerbations.
• Illustrated below are different treatment devices for transferring energy into the airways. Described below are just some of the examples of the type of treatment devices which may be used to treat airway tissue according to the present invention. It should be recognized that each of the treatment devices described below can be modified to deliver or to remove energy in different patterns depending on the treatment to be performed. The treatment devices may be actuated continuously for a predetermined period while stationary, may be pulsed, may be actuated multiple times as they are moved along an airway, may be operated continuously while moving the device in an airway to achieve a “painting” of the airway, or may be actuated in a combination of any of these techniques. The particular energy application pattern desired can be achieved by configuring the treatment device itself or by moving the treatment device to different desired treatment locations in the airway.
• The treatment of an airway with the treatment device may involve placing a visualization system such as an endoscope or bronchoscope into the airways. The treatment device is then inserted through or next to the bronchoscope or endoscope while visualizing the airways. Alternatively, the visualization system may be built directly into the treatment device using fiber optic imaging and lenses or a CCD and lens arranged at the distal portion of the treatment device. The treatment device may also be positioned using radiographic visualization such as fluoroscopy or other external visualization means. The treatment device which has been positioned with a distal end within an airway to be treated is energized so that energy is applied to the tissue of the airway walls in a desired pattern and intensity. The distal end of the treatment device may be moved through the airway in a uniform painting like motion to expose the entire length of an airway to be treated to the energy. The treatment device may be passed axially along the airway one or more times to achieve adequate treatment. The “painting-like” motion used to exposed the entire length of an airway to the energy may be performed by moving the entire treatment device from the proximal end either manually or by motor. Alternatively, segments, stripes, rings or other treatment patterns may be used.
• According to one variation of the invention, the energy is transferred to or from an airway wall in the opening region of the airway, preferably within a length of approximately two times the airway diameter or less, and to wall regions of airways distal to bifurcations and side branches, preferably within a distance of approximately twice the airway diameter or less. The invention may also be used to treat long segments of un-bifurcated airway.
Decreasing Resistance to Airflow
• There are several ways to decrease the resistance to airflow though the airways which occurs in asthma patients both at rest and during an asthma attack. One such treatment alters the structure of the airway, such as by reducing the amount of airway tissue. For example, the addition of energy to the airway tissue may cause the DNA of the muscle cells to become cross linked. The smooth muscle cells with cross linked DNA cannot replicate. Thus, over time, as smooth muscle cells die, the total thickness of the muscle decreases because of the inability of the cells to replicate. Another treatment alters the function of the airway, such as by reducing smooth muscle contraction, mucus gland secretions, or disrupting the inflammatory response. These treatments can be performed by applying energy of different types and in different patterns to achieve the desired results. In such cases, stiffness of the airway is increased as the energy induces a fibrosis or wound healing response that causes trauma to the airway wall.
• FIGS. 1 and 2 illustrate cross sections of two different airways in a healthy patient. The airway ofFIG. 1 is a medium sized bronchus having an airway diameter D1 of about 3 mm.FIG. 2 shows a section through a bronchiole having an airway diameter D2 of about 1.5 mm. Each airway includes a folded inner surface orepithelium10 surrounded bystroma12 andsmooth muscle tissue14. The larger airways including the bronchus shown inFIG. 1 also havemucous glands16 andcartilage18 surrounding thesmooth muscle tissue14.Nerve fibers20 andblood vessels22 also surround the airway.
• FIG. 3 illustrates the bronchus ofFIG. 1 in which thesmooth muscle14 has hypertrophied and increased in thickness causing the airway diameter to be reduced from the diameter D1 to a diameter D3.
• FIG. 4 is a schematic side view of the lungs being treated with anenergy transferring apparatus30 according to the present invention. Thedevice30 is an elongated member for facilitating exchanging energy with a mass of airway tissue at atreatment site34 within the lungs. Thedevice30 must be of a size to access the bronchus or bronchioles of the human lung. The device may be sized to fit within bronchoscopes, preferably, with bronchoscopes having a working channel of 2 mm or less. Also, the device should be of sufficient stiffness to fit and operate through the seal covering the working channel a bronchoscope.
• The energy may be delivered by thetreatment device30 in a variety of treatment patterns to achieve a desired response. Examples of patterns are discussed in further detail below. The energy which is delivered by thetreatment device30 may be any of a variety of types of energy including, but not limited to, radiant, laser, radio frequency, microwave, heat energy, or mechanical energy (such as in the form of cutting or mechanical dilation).
• Also, the device may, but is not necessarily, configured to deliver energy in non-intersecting strip patterns which are parallel with a central axis of an airway. For example, other variations of the device may be configured to deliver energy in a torsional pattern, or in a circumferential pattern around a wall of the airway. Such configurations which may be determined to deliver energy to the airway tissue that maximize the ability of the airway to permit airflow are considered to be within the scope of this invention.
• The inventive devices include tissue contacting electrodes configured to be placed within the airway. These devices can be used for delivering radio frequency in either a monopolar or a bipolar manner or for delivering other energy to the tissue, such as conducted heat energy from resistively heated elements. As shown inFIG. 4, for monopolar energy delivery, one or more electrodes of the treatment device are connected to a single pole of theenergy source32 and an optionalexternal electrode44 is connected to an opposite pole of the energy source. For bipolar energy delivery, multiple electrodes are connected to opposite poles of theenergy source32 and theexternal electrode44 is omitted. Naturally, theexternal electrode44 depicted inFIG. 4, is not required in the case of bipolar energy delivery. The number and arrangement of the electrodes may vary depending on the pattern of energy delivery desired. The treatment devices ofFIGS. 5A-10, and12-20 are used to deliver radiant or heat energy to the airway. The treatment device ofFIG. 11 may also be used to deliver indirect radio frequency, microwave energy, or conductive heat energy to the tissue. In cases of heat energy generated by resistive heating, the current may be AC or DC current or in the case of AC, the current may be delivered in the RF range. The use of RF provides an added safety feature of minimizing the possibility of harm to the patient caused by escaped current. The device may also use a combination of any of the energy transferring element configurations described herein.
• The following illustrations are examples of the invention described herein. It is contemplated that combinations of aspects of specific embodiments or combinations of the specific embodiments themselves are within the scope of this disclosure.
• Thetreatment device302 ofFIG. 5A includes anelongated member102 for delivering anexpandable member104 to a treatment site. Theexpandable member104 may have a plurality of energy transfer elements (not illustrated) which are placed on a plurality ofbasket legs106 to transfer energy at the treatment site. In this variation, the expandable member comprises abasket104 which is defined by a number ofbasket legs106. Thebasket legs106 are formed from a plurality of elements which are soldered or otherwise connected together at two connection areas, a proximal joint108 and adistal joint110.
• A desirable length of thebasket104, or the expandable portion of any variation of the invention, depends upon numerous factors. One consideration in determining a desired length of the expandable member, e.g., the distance between the joints of the basket, of the inventive device is related to the dimension of the target area or treatment region. For instance, some other factors include considerations of minimizing the amount of the expandable portion which is distal to the treatment region for optimized access, minimizing the amount of the expandable portion that is proximal to the treatment region for visualization and access concerns, and setting a desirable length of the expandable portion that will contact a sufficient portion of the treatment region during each application of the device. A compromise of such factors along with other considerations provides a desirable length for the expandable portion of the device. Preferably, the distance between the distal and proximal joints of the basket is less than 35 mm when the basket is in a first unexpanded state.
• Thelegs106 may be selected from a material that allows the basket to expand without plastic deformation. For example, the legs may comprise a stainless steel, or a shape memory/superelastic alloy such as a nitinol material. Thebasket legs106 may have a rectangular cross section in those variations where thelegs106 are formed from ribbons, or thelegs106 may have a circular cross section in those variations where the legs are formed from wires. As discussed below, thelegs106 may also have other cross section as desired. It is also contemplated that thelegs106 need not all have similar cross sections. For instance, the cross section of each of thelegs106 in abasket104 may be individually chosen to optimize such factors as the resilience of thebasket104, or to optimize energy transfer characteristics. The legs may also have a variable cross section along the length of the basket.
• Illustrated are variations of theinventive device302 having abasket104 comprising of fourlegs106. It is preferred that thelegs106 are spaced at equal intervals around the expandable member orbasket104. For example, in variations of the invention having fourlegs106, thelegs106 are preferably, but not necessarily spaced at approximately 90 degree intervals around thebasket104. In variations having fivelegs106, thelegs106 may be spaced at approximately 72 degree intervals. Other variations of the invention include devices having less than four legs or more than five legs. It is thought that the most effective number of legs is a compromise based on the size of the target airway, contact surface between theleg106 and airway wall, and the maximum outer diameter of theelongated member102.
• The proximal108 and/or distal110 joints may also contain adhesive to bind thelegs106. Thebasket legs106 between the proximal108 and distal joint110 are formed into thebasket shape104 so that arch shaped portions of thebasket legs106 will contact the walls of an airway to facilitate energy transfer. Although the figures illustrate thebasket legs106 as having a semi-circular or arc shape the device is not limited to such shapes. For example, thelegs106 may have a more oblong shape or sharper bends to allow for a more parallel leg surface area that contacts the target tissue. Eachleg106 may have a center that is substantially parallel to the elongated body so that there is sufficient contact between the airway walls and the parallel portion of theleg106. The center that is substantially parallel is usually referred to as the active region of theleg106.
• The length of thebasket104 between the proximal and distal110 joints may be less than 35 mm when thebasket104 is in a first unexpanded state. Thelegs106 may be coated with an insulating material (not shown) except at the tissue contact points. Alternatively, thelegs106 of thebasket104 may be exposed while the proximal108 and distal joint110 are insulated. In this variation, thebasket104 is formed of a resilient material which allows the distal end of theinventive device302 to be confined by a sheath (not shown) for delivery of thedevice302 to the treatment site and allows thebasket104 to return to its original basket shape upon deployment. In other words, a variation of the invention is that the basket self-expands from a first state to a second expanded state upon the removal of any constraining or restrictive member such as a sheath (not shown). Theinventive device302 is preferably configured such that thebasket legs106 have sufficient resilience to come into contact with the airway walls for treatment.
• FIG. 5A further illustrates a variation of theinventive device302 in which a distal end of thedevice302 is provided with adistal tip112 that can have a radius to facilitate insertion of thedevice302 into the lungs and also to minimize the possibility of causing trauma to surrounding tissue. Thetip112 is preferably sized to prevent the gouging of airway by the sheath. The design of the distal tip is selected to be atraumatic. The size of the tip may be selected to be large enough to prevent the sheath from gouging airways yet small enough to pass in and out of a bronchoscope.
• FIG. 5B illustrates a variation of theinventive device302 havingbasket legs108 connected to adistal end114 of theelongated member102 and forming abasket104. In this variation, a proximal joint is found at thedistal end114 of theelongated member102. Thebasket104 is expanded radially, to its second state, during use to ensure contact between the energy transfer elements (not shown) and the airway walls (not shown) by, for example, pulling on acenter pull wire116 which is connected to adistal tip118 of theexpandable portion104. Thecenter pull wire116 may extend through a lumen of theelongated member102 towards a proximal portion (not shown) of theelongated member102. It is also contemplated that thecenter pull wire116 may be configured to deliver current to the energy transfer elements found on theexpandable member104. Theinventive device302 may be delivered to a treatment site through adelivery sheath120 and may be drawn along or moved axially along the airway to treat the airway in a pattern of longitudinal or helical stripes.
• As noted above, thebasket104 may be resilient or self-expanding (e.g., seeFIG. 5A) to expand to a second expanded state or thebasket104 may require an expanding force (e.g., seeFIG. 5B). An example of this variation of theinventive device304 is shown inFIG. 5B. In this variation, thebasket104 may be resilient and thesheath120 may comprise the deployment member. In this variation, when theelongate body102 andbasket104 are withdrawn into thesheath120, thebasket104 contracts within thesheath120 and assumes a first state. In one variation of the invention, upon advancing thebasket104 andelongate body102 out of thesheath120, thebasket104 may resiliently assume a second expanded state. In another variation of the invention, thebasket104 may assume a second expanded state with the aid of awire116. This wire may also be configured to deliver power to theenergy exchange elements106.
• FIG. 5C illustrates another variation of the inventive device where anelongated member102 of is configured to have a plurality of lumens140 so that each of thebasket legs106 are isolated within the lumens140 of theelongated member102 until thelegs106 exit theelongated member102 and connect at a proximal joint108. The invention may havebasket legs106 selected with a sufficient length such that the ends of each of thelegs106 extend substantially into the lumens140. As a result of being inserted deeply within the lumen, the ends of thelegs106 would require significant travel before they exited the lumen140. This feature provides added safety as it minimizes the risk of thebasket legs106 dislodging from theelongate member102.
• In another variation of the invention, theelongated member102 may comprise concentric tubes (not shown) rather than multi-lumen tubes where basket legs are inserted in the annulus between the tubes. It is also contemplated that an elongated member may be reinforced with the use of a reinforcing member. Such a reinforcing member may include a coiled wire or polymeric insert.
• FIG. 5D-5I illustrate variations of the inventive device that use an expanding force to expand the basket.FIG. 5D illustrates a deployment member of the device.FIG. 5E illustrates the device ofFIG. 5D when the elongated member is moved in a distal direction to a deployment point.FIG. 5F-5G illustrates theelongated member102,sheath120,expandable member104,distal tip118, andwire122 extending through the device.FIG. 5F illustrates thebasket104 in a first unexpanded state when theelongated member102 andwire122 are proximal of thedeployment point130.FIG. 5G illustrates the expansion of thebasket104 to a second expanded state as theelongated member102 moves distally and thewire122 is restrained at thedeployment point130.
• Turning now toFIG. 5D, the deployment member may comprise ahandle124 which is adjacent to a proximal portion of anelongated member102. The handle may be designed to be operated by a single hand, either right or left. The handle may also have a control switch for operation of the device. Such a switch could control the power supply attached to the device as well. Also, the handle may be configured to determine the position of the device within a human body as the device is advanced to a target site. For example, marks on the handle or even a readout could provide information to the user as to the relative deployment state of the expandable member. Also, a sensor may be placed on thehandle124, this sensor may be used to determine the position of the expandable member. Such a sensor could also be used to measure the size of the airway, such a measurement could be used as a control variable to determine the amount of energy that the device power supply must deliver. Thehandle124 may control the expandable member using force compensation (e.g., a spring, etc.) or deflection limiting stops to control the expansion of the expandable member. Such force compensation or deflection stops provide a limit to the expansion member to avoid over-expansion of a particular airway.
• Turning now to thehandle124 ofFIG. 5D, anelongated member102 may be slidably mounted to the handle. The variation of the invention depicted in these Figures may also, but does not necessarily, include asheath120 exterior to theelongated body102. Awire122 extends from the handle through theelongated member102 and may be attached to adistal tip118 of the device. Thewire122,elongated member102, and distal tip (not shown) are slidably moveable in both a distal and proximal directions. The handle may also include astop126 which prevents thewire122 from moving distally beyond adeployment point130. Thestop126 may be connected to a spring (not shown) to limit the expansion of the expandable member upon reaching a pre-determined force. Thehandle124 may include acontrol member128 that is moveably attached to thehandle124 for moving theelongated member102 in a distal/proximal direction. Although thehandle124 in the figures is depicted to have acontrol member128 as illustrated, other variations of control members are also contemplated to be within the scope of this invention. For example, though not illustrated, ahandle124 may include other configurations, such as lever, thumb-wheel, screw-mechanism, ratchet mechanism, etc., which are attached to thehandle124 to provide control actuation for the expandable member.
• FIG. 5E illustrates a variation of the inventive device when theelongated member102 andwire122 are moved in a distal direction. In this illustrations, astop126 prevents thewire122 from moving distally of adeployment position130. This illustration further illustrates a variation of the invention where thestop126 is attached tosprings127 which provide force compensation for the expandable member on the device. Although not shown, acontrol member128 may have a stop which limits its travel along ahandle124. Such a stop is an example of a deflection limiting mechanism which controls the movement of thecontrol member128, thus controlling the extent of the expansion of the expandable member.
• FIG. 5F illustrates the invention when the expandable member orbasket104 is in a first unexpanded state. As noted above, thewire122 is attached to adistal tip118 of the device and both are prevented from distal movement when thewire122 is in thedeployment position130. Therefore, as depicted inFIG. 5G, movement of theelongated member102 in a distal direction against adistal tip118, that is restrained by awire122, causes abasket104 to compress between the advancingelongated member102 and the stationarydistal end118. Thus, thebasket104 is forced outward and radially expands into a second expanded state. As noted above, thewire122 may also be used to transfer energy to or from the energy transfer elements found on thebasket104. Also, it is contemplated that thewire122 may be a wire, a ribbon, a tube, or of any other equivalent structure. Also contemplated, but not shown, is a detent means for maintaining the elongated member in a distal position to expand thebasket104 against thedistal tip118 without the need for continual applied force by a user of the device. Also contemplated is a ratchet member, or friction member to maintain thebasket104 in the expanded state.
• FIG. 5H illustrates another variation of a deployment member. In this variation, asheath120 may be slidably attached to ahandle124. In this variation, theelongate member102 is rigidly attached to thehandle124. Thesheath120 may be attached to afirst control member129. Awire122 extends through theelongate member102 and is attached to the distal tip of the device (not shown). Thewire122 may be attached to asecond control member131. As indicated inFIG. 5I, proximal movement of thefirst control member129 causes thesheath120 to proximally retract over theelongate member102 and uncover the expandable portion (not shown). Proximal movement of thesecond control member131 causes thewire122, distal joint, and expandable member to move against the non-movingelongate member102 which causes the expandable member to expand into a second state.
• Turning now to the energy transfer elements located on the expandable portion,FIG. 5J-5L illustrate examples of energy transfer elements that may be located on the expandable portion of the device. In the variation of the invention where the expandable portion comprises a basket havingbasket legs106, thebasket legs106 may function as heat exchange elements. In other words, the device may be configured so that the leg is an electrode or the conductive heating element. In these variations, theleg106 may be partially covered with an insulation only leaving an active region exposed for delivery of energy to the airways. Examples of such insulation include a heat shrink sleeve, a dielectric polymeric coating, or other material which may function as an insulator.
• FIG. 5J illustrates an example of abasket leg106 with anenergy transferring element132 coiled around theleg106. In this example, the energy transferring element uses conductive heating and comprises aresistance heating element132 coiled around theleg106.FIG. 5K illustrates a variation of the invention having an RF electrode attached to thebasket leg106. The RF electrode may be attached to thebasket leg106 via the use of afastener134. For example, the electrode may be attached via the use of aheat shrink fastener134, (e.g., polymeric material such as PET or polyethylene tubing).
• FIG. 5L illustrates another variation of the invention where the energy transfer element is a printedcircuit138 that is situated around theleg106 and secured to the leg. Also contemplated, but not shown for use as energy transfer elements are a polymeric heating material, an electrically conductive paint, a resistance element sputtered onto the leg in a pattern or formed on a substrate by photofabrication. Also, the basket leg itself may be chosen of appropriate size and resistivity to alloy dual use as a basket and energy transfer element. Many nickel-chromium alloys have both high specific resistance and significant spring-like properties. In any variation of the invention the use of adhesives or other coatings may also be used to secure the energy transfer element to thebasket leg106. Also, the energy transfer elements are not limited to what is illustrated in the drawings. It is also contemplated that other types of energy transferelements may be used such as radiant, laser, microwave, and heat energy.
• FIG. 6A illustrates a variation of adistal tip210 having a redundant joint. Thedistal tip208 has apolymeric cap210 covering the distal ends of thebasket legs106 andwire212. Thelegs106 are soldered214 to the distal end of thewire212. Also used to maintain the joint is an adhesive216 substantially filling thepolymeric cap210. Amulti-lumen piece218 separates thelegs106 andwire212. A side view of themulti-lumen piece218 is shown inFIG. 6B. A multi-lumen tubing may be used for themulti-lumen piece218. The ends220 of thepolymeric cap210 may be heat formed or otherwise tapered down around thelegs106.
• FIG. 6C illustrates another variation of adistal tip222 having a redundant joint. Thedistal tip222 has apolymeric cap210 covering the distal ends of thebasket legs106 andwire212. Thelegs106 are soldered214 to the distal end of thewire212. Also used to maintain the joint is an adhesive216 substantially filling thepolymeric cap210. A hypo-tube224 covers thelegs106 andwire212. A side view of the hypo-tube224 is shown inFIG. 6D. The distal end of the hypo-tube224 may be flared to seat a ball located on a distal end of thewire212 and thelegs106. A proximal end of the hypo-tube224 may be flared to provide greater interlock withends220 of thepolymeric cap210. As shown inFIG. 6C, the ends of thelegs106 taper outwards from the hypo-tube224 and form an area with a diameter larger than the end of thecap226 which may be tapered down around thelegs106 andwire212. The ends220 of thepolymeric cap210 may be heat formed or otherwise tapered down.
• FIG. 6E shows another variation of the invention having a hoop orring228 at a proximal joint of the device. Thehoop228 may be soldered or welded to thelegs106 and keeps thelegs106 attached even if a joint fails between the legs and theelongate member102. Also, thehoop228 may electrically connect the legs, preventing disconnection ofsingle leg106 having a temperature sensing element attached.
• The invention also includes a temperature detecting element (not shown). Examples of temperature detecting elements include thermocouples, infrared sensors, thermistors, resistance temperature detectors (RTDs), or any other apparatus capable of detecting temperatures or changes in temperature. The temperature detecting element is preferably placed in proximity to the expandable member. In the variation illustrated inFIG. 5C, a temperature sensor may be mounted along thepull wire116. For the variations depicted inFIG. 5J-5L, a temperature sensor may be mounted between theenergy transfer elements132,136,138 and theleg106. In one variation of the invention a temperature sensor is placed on asingle basket leg106 to provide a signal to control energy transfer. It is also contemplated that a temperature sensor may be placed on more than onebasket leg106, and/or on acentral wire116 to provide control for multiple areas of energy transfer. The temperature sensor may be placed on the inside of thebasket leg106 to protect the temperature sensor while still providing a position advantageous to determining the device temperature at the energy transfer element.
• FIG. 5M illustrates a variation of the invention having thermocouple leads139 attached to aleg106 of the device. The leads may be soldered, welded, or otherwise attached to theleg106. This variation of the invention shows both leads139 of thethermocouple137 attached in electrical communication to aleg106 atseparate joints141. In this case, the temperature sensor is at the surface of the leg. This variation provides in case either joint becomes detached, the circuit will be open and thethermocouple137 stops reading temperature. The device may also include both of the thermocouple leads as having the same joint.
• FIG. 7A-7D illustrate variations of the device in which impedance may be varied by wiring thebasket legs106 in series or in parallel.FIG. 7A illustrates a series wiring diagram in which acurrent path142 flows from a first leg to asecond leg106, athird leg106, and afourth leg106 sequentially.FIG. 7B illustrates the series wiring diagram and shows asingle wire143 connecting thelegs106 in series. Thewire143 may, for example, extend to a distal end of the leg and wrap over itself to the proximal end of theleg106. A covering (not shown) may be placed over thewire143 wrappedleg106 at the proximal end of the device.FIG. 7C illustrates another variation of a series wiring diagram. In this example, awire143 extends from the proximal end of aleg106 to its distal end and then extends to the distal end of anadjacent leg106 and extends back to the proximal end of theadjacent leg106.
• FIG. 7D illustrates a parallel wiring diagram in which acurrent path142 flows to eachleg106. Series wiring has an added advantage in that all current will pass through each energy transfer element. By design, this configuration equalizes the heat dissipated at each leg through construction of legs with equal resistance. In addition, in the event of failure of any electrical connection, no energy is delivered. This provides an additional safety feature over parallel wiring. As mentioned elsewhere, the electrical current may be AC or DC. AC may be delivered in the RF range as a safety measure additional to electrical isolation. DC may be used to allow a portable device powered by a battery pack or provide an energy source within the device itself.
• FIG. 8A-8C illustrates variation of thelegs106 of thebasket104. As discussed above, the legs may, for example, comprise a stainless steel, or a shape memory/superelastic alloy such as a nitinol material. Thebasket legs106 may have a rectangular cross section in those variations where thelegs106 are formed from ribbons, or thelegs106 may have a circular cross section in variations where thelegs106 are formed from wires. Also, aleg106 may be configured to have a non-axisymmetric cross-section. For example, the leg may have an oval or flat cross section as well. Thelegs106 of abasket104 need not all have similar cross sections. For instance, the cross section of each of thelegs106 in abasket104 may be individually chosen to optimize such factors as the resilience of thebasket104, or to optimize energy transfer characteristics. An example of a cross section of abasket leg106 is seen inFIG. 8A which illustrates a top view of abasket leg106 that has a contouredshape144. In this illustration, the energy exchange element is not shown in the figure for clarity. One of the purposes of such acontoured shape144 is illustrated inFIG. 8B. When the basket (not shown) expands to its second state,leg106 is configured to bend at or substantially near to points146. A benefit of such a configuration is to allow a substantially parallel active surface as defined by thecontour shape144.FIG. 8C illustrates another variation of aleg106. In this variation, theleg106 has a region of increaseddiameter148 in the case of round wire, or increased width or thickness in the case of rectangular or other non-axisymmetric wire. Such aregion106 could also be a flat wire with bumps or protrusions creating areas of increased width of the flat wire. Thisregion148 may, for example, provide a stop that assists in locating insulation, heat shrink, or other external covering around theleg106. Also contemplated is aleg106 that consists of a composite construction. In this variation, theleg106 may comprise of differing materials in predetermined regions to control the bending of theleg106 as thebasket104 expands, or the leg may be constructed of different materials to selectively control regions of deliver of energy on the leg.
• FIG. 9A-9D illustrates another variation of the inventive device in which the expandable member comprises basket from a single piece or sheet of material. Such a configuration could comprise an etched, machined, laser cut, or otherwise manufactured piece of metal.FIG. 9A illustrates a partial view of abasket104 formed from a single piece of material. The thickness of the material is, for example 0.005 inches but may vary as desired. The illustration ofFIG. 9A shows thebasket104 prior to being wrapped about the Z direction as indicated. As shown, thelegs106 may be of varying length or they may be thesame length106 or a combination thereof. Thebasket104 may have adistal portion164 orbasket head164 which may be configured to facilitate construction of the device. For example, thebasket head164 may be notched166 to obtain a desired shape as the basket is wrapped about the Z direction.FIG. 9B illustrates a variation of thebasket head165 being notched such thatsections165 of the material may be bent from the plane of the material to formtabs165.Tabs165 may be used to form mechanical joints with another part, such as a distal tip cap.FIG. 9C illustrates another variation of abasket104 made from a single piece of material. In this example, thelegs106 of thebasket104 are bent in a direction orthogonal to the plane of thebasket head164. In this example, the distance between the ends of thelegs106 may be, for example, about 2.75 inches.FIG. 9D illustrates a variation of the proximal ends of thelegs106 of thebasket104. In this example, the proximal ends of thelegs106 may havefeatures168 which promote the structural integrity of the proximal joint (not shown) of the device. In this variation, the ends of thelegs106 have a saw-tooth design which improve the integrity of the proximal joint connecting thelegs106 to the elongated member. The variation ofFIG. 9D also illustrates a proximal end of theleg106 as having a radius, however, the end of theleg106 may have other configurations as required. Also, thelegs106 may have a width of, for example, 0.012 inches and a separation of, for example, 0.016 inches. However, these dimensions may vary as needed.
• FIG. 10 illustrates another variation of theinventive device306 in which the expandable member comprises aballoon member150. This variation of thedevice306 includeselectrodes154 positioned on an exterior surface of theballoon member150. Theelectrodes154 may be connected to an energy source (not shown) byleads156 extending through the balloon and through the lumen of anelongated member102. Theballoon member150 may be filled with a fluid152 such as saline or air to bring theelectrodes154 into contact with theairway wall10. As noted above, the electrodes may also be resistance heating elements, RF electrodes, or another suitable element for conducting energy transfer with the airway. Also, a single electrode may continuously surround a circumference of aballoon150, or a plurality of electrodes may be spaced at certain intervals to substantially surround the circumference of aballoon150.
• FIG. 11 illustrates another variation of theinventive device308 in which the expandable member comprises aballoon member150 in which afluid152 within theballoon member150 is heated by aheat generating element158. Theheat generating elements158 are illustrated in the shape of coils surrounding the shaft of theelongated member102, however other types of heat generating elements (not shown) shapes may also be used. Theheat generating elements154 may be used as resistance heaters by application of an electric current to the heat generating elements. Alternatively, radio frequency or microwave energy may be applied to theheat generating elements158 to heat fluid152 within theballoon member150. The fluid may be configured to optimize conductive heat transfer from theelectrodes158 to the exterior of theballoon member150. The heat then passes from an exterior of theballoon150 to theairway wall10. Radio frequency or microwave energy may also be applied indirectly to the airway wall through the fluid and the balloon. In addition, hot fluid may be transmitted to theballoon member150 from an external heating device for conductive heating of the airway tissue.
• Another variation of theinventive device310 is illustrated inFIG. 12 includes a plurality ofenergy transfer elements162 positioned onpre-shaped tines160. Thepre-shaped tines160 may be outwardly biased such that they expand from a first shape insidesheath120 into a second expanded shape once advanced out ofsheath120. Thetines160 may also be configured so that they retract into a first state once withdrawn into asheath120. Thepre-shaped tines160 may be connected to anelongate member102 which is positioned within asheath120. Thepre-shaped tines160 and theenergy transfer elements162 may be delivered through adelivery sheath120 to a treatment site within the airways. When thepre-shaped tines160 exit a distal end of thesheath120, thepre-shaped tines160 may bend outward until theenergy transfer elements162 come into contact with the airway walls for transfer of energy with the airway walls.
• FIG. 13 illustrates a variation of theinventive device314 in which aelongated member102 is provided with a plurality ofenergy transfer elements170 positioned on at least oneinflatable balloon172. Theenergy transfer elements170 may be RF electrodes or resistance heating elements. Theballoons172 are inflated through theelongated member102 to cause theenergy transfer elements170 to come into contact with theairway walls10. Theenergy transfer elements170 are preferably connected to the energy source (not shown) by conductive wires (not shown) which extend from theenergy transfer elements170 through or along theballoons172 and through theelongated member102 to the energy source. In the variation where theenergy transfer elements170 are RF electrodes, theelectrodes170 may be used in a bipolar mode without an external electrode. Alternatively, theinventive device314 may be operated in a monopolar mode with an external electrode (not shown, seeFIG. 4). Another variation of the invention includes using resistance heating elements as theenergy transfer elements170. Theenergy transfer elements170 may be a single continuous circular element or there may be a plurality ofelements170 spaced around theballoons172.
• An alternative of theinventive device316 ofFIG. 14 includes anelongated member102 having one ormore grooves174 in an exterior surface. Positioned within thegrooves174 areelectrodes176 for delivery of energy to the airway walls. Although thegrooves174 have been illustrated in a longitudinal pattern, the grooves may be easily configured in any desired pattern. Preferably, theinventive device316 ofFIG. 14 includes a biasing member (not shown) for biasing theelongated member102 against an airway wall such that theelectrodes176 contact airway tissue. The biasing member (not shown) may be a spring element, an inflatable balloon element, or other biasing member. Alternatively, the biasing function may be performed by providing a preformed curve in theelongated member102 which causes the device to curve into contact with the airway wall when extended from a delivery sheath (not shown).
• FIG. 15 illustrates a variation of theinventive device318 having one ormore electrodes178 connected to a distal end of anelongated tube102. Theelectrodes178 are supported between the distal end of theelongated tube102 and adistal tip180. A connectingshaft182 supports thetip180. Also connected between the distal end of theelongated member102 and thedistal tip180 is aspring element184 for biasing theelectrodes178 against a wall of the airway. Thespring element184 may have one end which slides in a track or groove in theelongated member102 such that thespring184 can flex to a variety of different positions depending on an internal diameter of the airway to be treated.
• FIG. 16 illustrates an alternative of theinventive device320 in which the one ormore electrodes186 are positioned on abody188 secured to an end of anelongated member102. In theFIG. 16 variation, thebody188 is illustrated as egg shaped, however, other body shapes may also be used. Theelectrodes186 extend throughholes190 in thebody188 and along the body surface. A biasing member such as aspring element184 is preferably provided on thebody188 for biasing the body with theelectrodes186 against the airway walls.Leads192 are connected to theelectrodes186 and extend through theelongated member102 to the energy source not shown.
• FIGS. 17 and 18 illustrate embodiments of theinvention322,324 in whichelectrodes194 in the form of wires are positioned in one ormore lumens196 of anelongated member102.Openings198 are formed in side walls of theelongated member102 to expose theelectrodes194 to the surrounding tissue. As shown inFIG. 17, theinventive device322 may havemultiple lumens196 withelectrodes194 provided in each of thelumens196. The side wall of theinventive device322 is cut away to expose one or more of theelectrodes194 through aside wall opening198. InFIG. 17, theopening198 exposes twoelectrodes194 positioned in adjacent lumens. Theinventive device322 may be provided with a biasing member as discussed above to bring the electrodes195 of the device into contact with the airway wall.
• Another variation of theinventive device324 as shown inFIG. 18 includes anelongated member102 which has an expandable loop shapedmember202 to allow theelectrodes194 to be exposed on opposite sides of thedevice324 which contacts opposite sides of the airway. The resilience of the loop shapedmember202 causes theelectrodes194 to come into contact with the airway walls.
• FIGS. 19 and 20 illustrate a further variation of theinventive device326 having anexpandable member204 in a first non-expanded state and in a second expanded state.FIG. 19 illustrates the device as having one or more loop shapedelectrodes204 connected to anelongated member102. In the unexpanded position shown inFIG. 19, the loop of theelectrode204 lies along the sides of acentral core206. A distal tip of theloop electrode204 is secured to thecore206 and to adistal tip208. Thecore206 may be slidable in a lumen of theelongated member102. Once theinventive device326 has been positioned with the distal end in the airway to be treated, theelectrode204 is expanded by pulling thecore206 proximally with respect to theelongated member102, as shown inFIG. 20. Alternatively, theelectrode204 or thecore206 may be spring biased to return to a configuration ofFIG. 20 when a constraining force is removed. This constraining force may be applied by a delivery sheath or bronchoscope through which theinventive device326 is inserted or by a releasable catch.
• The treatment of the tissue in the airway walls by transfer of energy according to the present invention provides improved long term relief from asthma symptoms for some asthma sufferers. However, over time, some amount of smooth muscle or mucus gland cells which were not affected by an initial treatment may regenerate and treatment may have to be repeated after a period of time such as one or more months or years.
• The airways which are treated with the device according to the present invention are preferably 1 mm in diameter or greater, more preferably 3 mm in diameter. The devices are preferably used to treat airways of the second to eighth generation, more preferably airways of the second to sixth generation.
• Although the present invention has been described in detail with respect to devices for the treatment of airways in the lungs, it should be understood that the present invention may also be used for treatment of other body conduits. For example, the treatment system may be used for reducing smooth muscle and spasms of the esophagus of patients with achalasia or esophageal spasm, in coronary arteries of patients with Printzmetal's angina variant, for ureteral spasm, for urethral spasm, and irritable bowel disorders.
• The devices and method describe herein provide a more effective and/or permanent treatment for asthma than the currently used bronchodilating drugs, drugs for reducing mucus secretion, and drugs for decreasing inflammation.
• Moreover, the inventive device may also include a steering member configured to guide the device to a desired target location. For example, this steering member may deflect a distal tip of the device in a desired direction to navigate to a desired bronchi or bronchiole. Also contemplated it the use of the device with a vision system. Such a vision system may comprise a fiber optic cable which allows a user of the device to guide a distal tip of the device to its desired location. The vision system may include a CCD chip.
• Also contemplated as the inventive device is the use of a power supply for providing energy as described above. The power supply provides the energy to be delivered to airway tissue via the energy transfer device. While the main goal of the power supply is to deliver enough energy to produce the desired effect, the power supply must also deliver the energy for a sufficient duration such that the effect persists. This is accomplished by a time setting which may be entered into the power supply memory by a user.
• A power supply may also include circuitry for monitoring parameters of energy transfer: (for example, voltage, current, power, impedance, as well as temperature from the temperature sensing element), and use this information to control the amount of energy delivered.
• A power supply may also include control modes for delivering energy safely and effectively. Energy may be delivered in open loop power control mode for a specific time duration. Energy may also be delivered in temperature control mode, with output power varied to maintain a certain temperature for a specific time duration. In the case of RF energy delivery via RF electrodes, the power supply may operate in impedance control mode.
• In temperature control mode with RF electrodes described here, the power supply will operate at up to a 75° C. setting. The duration must be long enough to produce the desired effect, but as short as possible to allow treatment of all of the desired target airways within a lung. For example, 5 to 10 seconds per activation (while the device is stationary) is preferred. Shorter duration with higher temperature will also produce acceptable acute effect.
• Using RF electrodes as described above in power control mode, power ranges of 10-15 W with durations of 3-5 seconds are preferred but may be varied. It should be noted that different device constructions utilize different parameter settings to achieve the desired effect. For example, while direct RF electrodes typically utilize temperatures up to 75° C. in temperature control mode, the resistively heated electrodes may utilize temperatures up to 90° C. Also, in addition to the control nodes specified above, the power supply may include control algorithms to limit excessive thermal damage to the airway tissue. For example, in order to stop delivery of energy in the event of contact between airway tissue and device legs having temperature sensing capabilities, an algorithm may be employed to shut down energy delivery if the sensed temperature does not rise by a certain number of degrees in a pre-specified amount of time after energy delivery begins. Another way to stop energy delivery includes shutting down a power supply if the temperature ramp is not within a predefined rage at any time during energy delivery. Other algorithms include shutting down a power supply if a maximum temperature setting is exceeded or shutting down a power supply if the sensed temperature suddenly changes, such a change includes either a drop or rise, this change may indicate failure of the temperature sensing element.
• Moreover, a variation of the invention includes configuring each energy exchange element independently to provide selective energy transfer radially about the device. As discussed above, another variation of the invention includes providing feedback control to determine the impedance of the airway to determine the power required by a power supply. Again, as discussed above, the feedback control could also be used to determine the size of the airway in which the device is positioned.
• Further details as to the use or other variation of the apparatus described herein may be drawn from the background which is intended to form part of the present invention. It is noted that this invention has been described and specific examples of the invention have been portrayed to convey a proper understanding of the invention. The use of such examples is not intended to limit the invention in any way. Additionally, to the extent that there are variations of the invention which are within the spirit of the disclosure and are equivalent to features found in the claims, it is the intent that the claims cover those variations as well. All equivalents are considered to be within the scope of the claimed invention, even those which may not have been set forth herein merely for the sake of brevity. Also, the various aspects of the invention described herein may be modified and/or used in combination with such other aspects also described to be part of the invention either explicitly or inherently to form other advantageous variations considered to be part of the invention covered by the claims which follow.

Claims (24)

1-78. (canceled)

79. An apparatus for delivering energy to airway tissue, comprising:

a flexible elongated body having a proximal portion and a distal portion;

a radially expandable electrode array including a rounded tip and at least four elongated flexible electrodes projecting from the distal portion of the body and longitudinally relative to the body, wherein each electrode has a proximal end attached to the distal portion of the elongated body, a distal end attached to the rounded tip, and an active region between the proximal and distal ends;

a first electric cable configured to be attached to one pole of an RF energy source and a first plurality of the electrodes, and a second cable configured to be attached to an opposite pole of the RF energy source and a second plurality of the electrodes, wherein the first and second cables provide RF energy to the first and second plurality of electrodes in a bipolar manner; and

a deployment member extending along the elongated body and attached to the rounded tip, wherein proximal movement of the deployment member flexes the electrodes such that the active regions move away from a longitudinal axis of the elongated body to contact the airway.

80. The apparatus ofclaim 79 wherein the electrodes are equally spaced apart from each other.

81. The apparatus ofclaim 79 wherein the active regions are approximately 10 mm long.

82. The apparatus ofclaim 79 wherein opposing active regions of the electrodes are diametrically spaced apart from each other by a distance of 10-12 mm in a fully flexed expanded state.

83. The apparatus ofclaim 79, further comprising a first thermocouple operatively coupled to one of the first plurality of electrodes and a second thermocouple operatively coupled to one of the second plurality of electrodes.

84. The apparatus ofclaim 79 wherein the electrodes are made from a flat wire positioned to flex so that the active regions move radially outward to a deployed configuration.

85. The apparatus ofclaim 79, further comprising a power source that provides RF energy in bipolar fields within airway tissue such that the electrodes reach a temperature of 65° C. for an activation time of at least 3 seconds.

86. The apparatus ofclaim 79, further comprising a power source that provides RF energy in bipolar fields within airway tissue such that the electrodes reach a temperature of 70° C. for an activation time of 2 seconds.

87. The apparatus ofclaim 79 wherein individual active regions form individual arches when moved radially outward.

88. An apparatus for delivering energy to airway tissue, comprising:

a flexible elongated body having a proximal portion and a distal portion;

a radially expandable electrode array including a rounded tip and at least four elongated flexible electrodes projecting longitudinally relative to the body, wherein each electrode has a proximal end attached to the distal portion of the elongated body, a distal end attached to the rounded tip, and an active region between the proximal and distal ends, and wherein the electrodes extend generally parallel to a longitudinal axis of the elongated body in a collapsed state and are configured to flex such that the active regions move radially outward relative to the longitudinal axis of the elongated body to contact the airway in an expanded state; and

a first electric cable configured to be attached to one pole of an RF energy source and a first plurality of the electrodes, and a second cable configured to be attached to an opposite pole of the RF energy source and a second plurality of the electrodes, wherein the first and second cables provide RF energy to the first and second plurality of electrodes in a bipolar manner such that airway smooth muscle tissue is debulked and the ability of the airway smooth muscle to contract is reduced.

89. The apparatus ofclaim 88 wherein the electrodes are equally spaced apart from each other.

90. The apparatus ofclaim 88 wherein the active regions are approximately 10 mm long.

91. The apparatus ofclaim 88 wherein opposing active regions of the electrodes are diametrically spaced apart from each other by a distance of 10-12 mm in a fully flexed expanded state.

92. The apparatus ofclaim 88, further comprising a first thermocouple operatively coupled to one of the first plurality of electrodes and a second thermocouple operatively coupled to one of the second plurality of electrodes.

93. The apparatus ofclaim 88 wherein the electrodes are made from a flat wire positioned to flex so that the active regions move radially outward to a deployed configuration.

94. The apparatus ofclaim 88, further comprising a power source that provides RF energy in bipolar fields within airway tissue such that the electrodes reach a temperature of 65° C. for an activation time of at least 3 seconds.

95. The apparatus ofclaim 88, further comprising a power source that provides RF energy in bipolar fields within airway tissue such that the electrodes reach a temperature of 70° C. for an activation time of 2 seconds.

96. The apparatus ofclaim 88 wherein individual active regions form individual arches when moved radially outward.

97. A method for treating asthma, comprising:

inserting a radially expandable electrode array into an airway in a lung of a patient, the radially expandable electrode array including at least four elongated flexible electrodes projecting from the distal portion of the body and longitudinally relative to the body, wherein each electrode has a proximal end attached to the distal portion of the elongated body, a distal end attached to a tip, and an active region between the proximal and distal ends;

flexing the electrodes such that the active regions move radially outward relative to a longitudinal axis of the elongated body and contact a wall of the airway, wherein individual active regions extend longitudinally along the wall of the airway; and

delivering RF energy to the wall of the airway via the electrodes in a bipolar manner such that airway smooth muscle tissue is debulked and the ability of the airway smooth muscle to contract is reduced.

98. The method ofclaim 97 wherein delivering the RF energy comprises heating the electrodes to at least 65° C. for at least 3 seconds and then terminating the RF energy.

99. The method ofclaim 97 wherein delivering the RF energy comprises heating the electrodes to approximately 70° C. for approximately 2 seconds and then terminating the RF energy.

100. The method ofclaim 97 wherein flexing the electrodes comprises moving the tip proximally, and wherein the method further comprises releasing the tip after terminating the RF energy such that the electrodes exert a longitudinal force that drives the tip distally and moves the active regions radially inward relative to the longitudinal axis of the elongated body.

101. The method ofclaim 97 wherein:

flexing the electrode comprises drawing a pull wire attached to the tip proximally such that the tip moves proximally;

delivering the RF energy comprises heating the electrodes to at least 65° C. for at least 3 seconds at a first treatment site in the airway and then terminating delivery of the RF energy;

releasing the pull wire after terminating delivery of the RF energy at the first treatment site, whereby the electrodes exert a longitudinal force that drives the tip distally and moves the active regions inward relative to the longitudinal axis of the elongated body;

moving the expandable electrode array proximally within the airway to a second treatment site;

pulling the pull wire proximally, which moves the tip proximally and causes the electrodes to flex such that the active regions move radially outward relative to the longitudinal axis of the elongated body and contact the wall of the airway at the second treatment site;

delivering the RF energy in a bipolar manner to the wall of the airway at the second treatment site such that the electrodes are heated to at least 65° C. for at least 3 seconds.

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