SELECTIVE LUNG TISSUE ABLATION

Abstract

Medical methods and systems are provided for effecting lung volume reduction by selectively ablating segments of lung tissue.

Claims

1. A treatment system for ablating a targeted treatment site in a lung of a patient, comprising: a shaft having a proximal end and a distal end; an energy emitting element disposed near the distal end of the shaft, wherein the energy-emitting element comprises an elongate member which will extend through the target site in the lung and an expansion element configured to enable the energy-emitting element to be expanded to conform to a shape of the airway of the treatment site; one or more electronic temperature sensors; and wherein said sensors are connected to a feedback control system configured to control the pressure or temperature between the targeted treatment site versus the neighboring lung tissue to selectively ablate lung tissue.

2. A treatment system as in claim 1, wherein the energy emitting element comprises an elongate coil shaped electrode.

3. A treatment system as in claim 1, wherein the energy emitting element comprises an elongate braided wire electrode.

4. A treatment system as in claim 1, wherein the expansion element comprises an inflatable balloon.

5. A treatment system as in claim 1, wherein the expansion element comprises a constraint which can be released to allow the expansion element to self-expand.

6. A treatment system as in claim 1, wherein the energy emitting element comprises an electrically resistive coil or a hot fluid element.

7. A method for selectively ablating a treatment region in a lung comprising: advancing a treatment apparatus through an airway toward the treatment region in the lung; exchanging energy through the treatment apparatus to heat or cool the treatment region to a level to collapse at least a portion the treatment region; and protecting adjacent regions in the lung and surrounding tissue from thermal damage by controlling pressure or temperature at the treatment region and at one or more untreated regions adjacent the treatment region.

8. A method as in claim 7, wherein the tissue is raised to a temperature in the range from 40° C. to 95° C.

9. A method as in claim 7, wherein the delivered energy comprises radiofrequency, alternating current, microwave, ultrasound, coherent light, incoherent light, radioisotopes, or a combination thereof.

10. A method as in claim 7, further comprising advancing at least one additional treatment apparatus toward the treatment site in the lung region and delivering energy to the treatment site through at least two treatment apparatuses.

11. A method as in claim 7, further comprising ventilating the patient's other lung.

12. A method as in claim 11, further comprising ventilating untreated region(s) of the lung adjacent to the treated region.

13. A method as in claim 7, further comprising controlling pressure and temperature simultaneously in the treatment site and in the one or more untreated regions adjacent the treatment site so that thermal damage to the non-targeted sites is minimized.

14. A method as in claim 7, further comprising introducing an electrically or thermally conducting fluid into the treatment site to improve energy distribution.

15. A method as in claim 14, further comprising deploying isolation barriers to inhibit the conductive fluid from migrating from the treatment site.

16. A method as in claim 7, wherein the treatment site comprises an entire lobe of the lung.

17. A method as in claim 7, further comprising monitoring the temperature within the treatment site and controlling the energy exchange to maintain a temperature within a desired range.

18. A method as in claim 7, further comprising: testing the patient to determine if the treatment site is subject to collateral ventilation; and ablating the treatment site only if the treatment site is subject to collateral ventilation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 illustrates an embodiment of a double lumen tube advanced into the dependent lung.

[0019] FIGS. 2A-2B illustrate example double lumen tubes.

[0020] FIGS. 3A-3B illustrate example endobronchial tubes.

[0021] FIG. 3C illustrates the endobronchial tube of FIGS. 3A-3B positioned in the anatomy with a treatment apparatus.

[0022] FIGS. 4-5 illustrate isolation/aspiration procedures.

[0023] FIGS. 6A-6B, 7, and 8A-8B illustrate embodiments of treatment apparatuses.

[0024] FIG. 9 illustrates the use of isolation balloons for containing an electrical or thermal conduction fluid within a treatment site.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The methods, apparatus, and systems of the present invention are used for delivering energy to diseased target sites within a patient lung for ablation and consequent isolation of the diseased segment to treat diseased lung regions resulting from emphysema, bronchitis, and other primary diseases. The treatment methods of the present invention are more rigorous than and intended as alternatives to the intrabronchial occlusion methods described previously for isolating diseased regions within a patient's lung. The methods of the present invention will be referred to generally hereinbelow as selective lung tissue ablation (SLTA).

[0026] Prior to treatment with the SLTA methods of the present invention, patients will usually be tested with a collateral ventilation (CV) test along with a segmental diagnostic test, such as described in U.S. patent application Ser. No. 11/296,951 (Attorney Docket No. 017534-002820US); and U.S. patent application Ser. No. 10/241733 (Attorney Docket No. 017534-1710US), both incorporated herein by reference for all purposes. Patients who test negative for the collateral ventilation test could probably benefit from the less traumatic endobronchial volume reduction treatment, which relies on placing occlusal stents in their target lung regions (U.S. Pat. No. 6,287,290). Patients who test positive for the CV measurements could be considered for the more invasive SLTA treatment procedure described herein. However, it should be appreciated that patients may receive the SLTA treatment based on a variety of reasons and will not necessarily undergo CV testing prior to receiving SLTA treatment.

[0027] The SLTA methods of the present invention may be used particularly for a treatment site in a lung that is supplied air through one or more collateral pathways. Such ablation may be desired to induce collapse in the lung region. In accordance with one aspect of the invention, there is disclosed a method of inducing one lung ventilation (OLV) in the emphysematous patient. This may be achieved with the use of a variety of devices. For example, FIG. 1 illustrates an embodiment of a double lumen tube 10 (such as manufactured by Mallinkcrodt Corp.) advanced into the dependent lung DL. Double lumen tube 10 in the formula Carlens tube are illustrated in FIGS. 2A-2B. FIG. 2B illustrates the Carlens tube of FIG. 2A inserted in a body lumen at a bifurcation, as it would be placed in the tracheal-bronchial tree.

[0028] OLV could also be introduced by other methods, such as with the use of an endobronchial blocker catheter. Or, with the use of a smaller diameter endobronchial tube 20, such as illustrated in FIGS. 3A-3B. The endobronchial tube may have, for example, a 6 mm ID and be shaped similarly to an endotracheal tube (C shaped to follow the curvature of the upper airway, but also would have a right or left sided curve for selective cannulation of the main stem bronchus). An isolation cuff 22 may have in general shape and pressure/volume characteristics which are similar to an endotracheal tube, however the cuff diameter would be smaller to accommodate the smaller size of the mainstem bronchus. This design would allow the bronchoscopist to advance any treatment apparatus alongside the tube while providing the necessary OLV procedure, as illustrated in FIG. 3C.

[0029] The left side of the lung (dependent lung DL) can thus be isolated and ventilated from the right side of the lung (nondependent lung NL). By puncturing the chest wall with a needle placed percutaneously, the nondependent lung NL can be collapsed. Alternatively, the puncture could be created from inside the inside of the lung, preferably through the wall adjacent to the treatment site that will be sealed during ablation. This separates the target lung region(s) from the chest wall which is intended to minimize thermal damage which may be caused by the ablation process.

[0030] Since emphysematous or other diseased lung tissue may not collapse easily on it's own, an isolation/aspiration procedure may optionally be performed to collapse the target lung region as much as possible. If, for example, the right upper lobe is diseased, an isolation sheath 30 may be introduced over a bronchoscope (as described in U.S. Pat. No. 6,585,639 incorporated herein by reference for all purposes) to isolate the target site (lobe or segment). An additional balloon tipped isolation catheter 32 may be introduced alongside of the sheath/bronchoscope device. The balloon 34 would be positioned the way, that the feeding bronchus to the RML (right middle lobe) and RLL (right lower lobe) both would get occluded. This would close airflow to the RML and RLL, and would prevent collateral channels to backfill the target RUL, thus enhance the collapse of the target lung area. Both of these devices may be introduced, for example, either via a double lumen tube or alongside of an endobronchial tube. After inflating the balloons, an aspiration device may be connected to the working channel of the bronchoscope to facilitate the collapse of the target lung region. The target lung region is thus collapsed as much as possible, as illustrated in FIG. 4 (expiration) and FIG. 5 (inspiration). A treatment apparatus may then be positioned at the treatment site.

[0031] Exemplary treatment apparatuses include a balloon tipped catheter, illustrated in FIGS. 6A-6B, a coil tipped catheter, illustrated in FIG. 7, and a braided wire electrode catheter, illustrated in FIGS. 8A-8B. The balloon-tipped catheter 40 comprises an inflatable balloon 42 or other radially expandable structure having a plurality of electrodes 44 on its outer surface. Inflation of a balloon within an airway of the target site of the lung can thus engage the multiple electrodes against the wall of the airway in order to deliver radiofrequency or other energy, as discussed below. The catheter 50 includes a radially expandably coil-shaped electrode 52 which is flexible and able to conform to the shape and size of the airway in which it is deployed. The catheter 60 carries a self-expanding braided wire electrode structure 62 which is carried in its non-expanded configuration while the catheter 60 is delivered to its target site within the lung. The electrode structure may then be released from constraint, for example, using a release wire 64 which is threaded through the braided electrode. Alternatively, the braided wire electrode structure 62 may be covered with a sheath (not shown) or other restraining structure which may be pulled back to release the sheath so that it can self-expand. In either case, the braided electrode structure can assume an expanded configuration which conforms to the inner wall of the airway A, as shown in FIG. 8B. In all cases, it may be desirable to introduce a conductive gel through the treatment site to enhance electrical conduction. The gel could be introduced on or by the treatment catheters or by other catheters or probes.

[0032] The treatment apparatus is positioned at the treatment site (for example one placed in segment B1 and an other placed in B2 of FIG. 1), and a bipolar RF generator may be activated to provide suitable radiofrequency (RF) energy, preferably at a selected frequency in the range of 10 MHz to 1000 MHz. The emitted energy is converted within the tissue into heat in the range of about 40.degree. C. to about 95.degree. C. As the temperature increases, it is believed that the collagen undergoes a structural transformation whereby the collagen fibers contract and new cross links are formed. If a full lobar ablation is needed, two, three, or more electrode catheters could be placed and either monopolar or bipolar RF energy could be used.

[0033] Selective thermal ablation of the lung tissue is believed to cause the collagen matrix to shrink, thereby reducing the size of the target lung segment as well as closing up the collateral channels to prevent reinflation. Deleterious effects in the cells making up the tissue begin to occur at about 42.degree. C. As the temperature of the tissue increases because of the heat generated by the tissue's resistance, the tissue will undergo profound changes and eventually, as the temperature becomes high enough, that is, generally greater than 45.degree. C., the cells will die. The change of tissue resistance or impedance could be monitored and used for controlling the depth of ablation. The zone of cell death is known as a lesion and the procedure followed to create the lesion is commonly called an ablation. As the temperature increases beyond cell death temperature, complete disintegration of the cell walls and cells caused by boiling off of the tissue's water can occur. Cell death temperatures can vary somewhat with the type of tissue to which the power is being applied, but generally will begin to occur within the range of 45.degree. C. to 60.degree. C., though actual cell death of certain tissue cells may occur at a higher temperature. Optionally, polymerizing gels can be introduced to the treatment site to promote collagen cross-linking and lung volume reduction.

[0034] In addition to RF energy, other forms of energy including alternating electrical current, microwave, ultrasound, and optical, such as coherent (e.g., laser) or incoherent (e.g., light emitting diode or tungsten filament), can be used, as well as thermal energy generated from an electrically resistive coil, a hot fluid element (e.g., circulating liquids, gases, combinations of liquids and gases, etc.), radioisotopes, and the like. Thermal energy also includes the use of cold media (cryo ablation). The hot fluid element may comprise, for example, an elongated member that includes a conduit system whereby heated fluid is transported through the center of the member and then channeled outward toward the inner surface of the member. In one embodiment the heated fluid is diverted to contact the inner surface of the elongated member so that energy radiates from selected areas on the outer surface of the member corresponding to areas. Regardless of the source, energy delivered to the target lung tissue should be such that only the selected lung regions are ablated, while they are away from the chest wall to minimize thermal damage. Optionally, tissue contraction and volume reduction can be enhanced by immediately cooling a heat-ablated treatment site. For example, liquid nitrogen can be introduced following ablation to induce permanent cross-linking of the collagen.

[0035] Neighboring lobes or segments can be ventilated or just pressurized by a cooler gas or liquid to minimize thermal damage to them as well. The isolation catheter 32 of FIG. 3C may be used to deliver cooling media to neighboring lobes, segments, or subsegments of the lung being treated. The balloon 34 tipped isolation catheter 30 would be introduced alongside of the treatment catheter 30. The balloon would be positioned in a manner so that the feeding bronchus to the RML (right middle lobe) and RLL (right lower lobe) both would be occluded. Both of these catheters would be introduced either via the double lumen tube or alongside of the EB tube. Treatment can be done on only one segment or a plurality of segments at once. The cooling media can be any gas or liquid, for example cooled air, cooled oxygen, or a cooled liquid, such as saline or perfluorocarbon, etc. By controlling the pressure and temperature simultaneously between the target lung region versus the neighboring lung tissue, selective lung tissue ablation can be achieved with minimal thermal damage to the non-targeted sites.

[0036] A conductive liquid such as isotonic or hypertonic saline could also be introduced into a lobe or a segment. Air would be desirable to be removed prior to instilling the liquid. An electrode pad may be placed under the patient's chest to provide grounding. Once the liquid is in place, an electrode or plurality of electrodes would be inserted into the proximal end of the liquid pathway to communicate electrically with the instilled conductive liquid. A monopolar RF source could be activated to cause the liquid to heat up to a specific temperature.

[0037] Referring now to FIG. 9, a treatment site TS in the right upper lung is isolated with a balloon catheter 100 having an isolation balloon 102 at its distal end. The right lower lung is isolated with a second balloon catheter 110 having an isolation balloon 112 at its lower end. A pair of secondary balloon catheters 120, 122 having isolation balloons 124, 126 is introduced through a central lumen of the catheter 100. The isolation balloons 124, 126 are advanced into selected airways and inflated to create an isolated region between the balloon 102 and the more distal isolation balloons 124 and 126. It will be appreciated that in some instances only a single secondary isolation balloon would be used, while in other instances, three or more secondary isolation balloons could be used. In all cases, an electrically or thermally conductive fluid is introduced through the catheter 100 into the isolated region created between the isolation balloons 102, 124, and 126. Energy can be transferred with the treatment site TS by delivering energy into the fluid, or optionally cooling the fluid to remove energy from the treatment site. In the case of electrically conductive fluids, radiofrequency or other energy may be introduced into the fluid from catheter 100, where the energy will be conducted throughout the electrically conductive fluid to treat the tissue. Alternatively, electrodes could be provided on the catheters 120 and 122. Still further alternatively, heating elements could be placed on the catheters 120 and 122, or elsewhere within the system in order to heat thermally conductive fluids.

[0038] Other alternative treatment is possible for closing up collateral channels: same One Lung Ventilation (OLV) technique combined with Video Assisted Thoracoscopic Surgery (VATS) and mechanically by clipping or using an RF based cut and seal device to separate the incomplete fissures between lobes. After that either EVR could be performed by placing the occlusal stents or thermal ablation would be required.

[0039] While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.