WO2017091803A1

WO2017091803A1 - Percutaneous tunneling devices and methods of use

Info

Publication number: WO2017091803A1
Application number: PCT/US2016/063755
Authority: WO
Inventors: Ali Rezai; Zibly ZION; Deogaonkar MILIND
Original assignee: Ohio State Innovation Foundation
Priority date: 2015-11-25
Filing date: 2016-11-25
Publication date: 2017-06-01

Abstract

A percutaneous tunneling device can include a tunneler housing with an inner lumen extending longitudinally through the tunneler housing. A removable stylet can be disposed within the inner lumen. The stylet can include at least one light source, at least one suction lumen extending longitudinally through the stylet, and at least one working lumen extending longitudinally through the stylet and being configured to receive at least one tissue dissection modality.

Description

PERCUTANEOUS TUNNELING DEVICES AND METHODS OF USE

RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62/259,995, filed November 25, 2015, the entirety of which is hereby incorporated by reference for all purposes.

TECHNICAL FIELD

[0002] The present disclosure relates generally to devices and methods for percutaneous surgical or medical procedures and, more particularly, to devices and methods that permit rapid, accurate, and safe percutaneous tissue dissection during various surgical or medical procedures.

BACKGROUND

[0003] Certain devices can be used during surgical and medical procedures to form a percutaneous tunnel in a subject. To facilitate tunnel formation, conventional tunneling devices require active force and pressure to maneuver the devices within the subject. These forces can cause the tunneling device to diverge into different paths or tissue planes from the planned path and penetrate different organs. During travel through the tissue, such devices can also cause subcutaneous bleeding by cutting tissue and rupturing blood vessels. Furthermore, the tissue dissection process can be slow, in particular with repeat operations, and thereby require additional time to complete tunnel formation. SUMMARY

[0004] The present disclosure relates generally to devices and methods for percutaneous surgical or medical procedures and, more particularly, to devices and methods that permit rapid, accurate, and safe percutaneous tissue dissection during various surgical or medical procedures.

[0005] One aspect of the present disclosure can relate to a percutaneous tunneling device that comprises a tunneler housing with an inner lumen extending longitudinally through the tunneler housing. A removable stylet can be disposed within the inner lumen. The stylet can include at least one light source, at least one suction lumen extending longitudinally through the stylet, and at least one working lumen extending longitudinally through the stylet and being configured to receive at least one tissue dissection modality.

[0006] One aspect of the present disclosure can relate to a percutaneous tunneling device consisting of a tunneler housing with an inner lumen extending longitudinally through the tunneler housing. A removable stylet can be disposed within the inner lumen. The stylet can include a light source, a suction lumen extending longitudinally through the stylet, and a working lumen extending longitudinally through the stylet and being configured to receive at least one tissue dissection modality.

[0007] Another aspect of the present disclosure can relate to a method for forming a tunnel in a target tissue of a subject. One step of the method can include providing a percutaneous tunneling device that includes a tunneler housing with an inner lumen extending longitudinally through the tunneler housing. A removable stylet can be disposed within the inner lumen. The stylet can include at least one light source, at least one suction lumen extending longitudinally through the stylet, and at least one working lumen extending longitudinally through the stylet and being configured to receive at least one tissue dissection modality. The at least one tissue dissection modality can be actuated while advancing the tunneler housing through the target tissue to simultaneously cut and cauterize the target tissue and thereby form the tunnel in the target tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing and other features of the present disclosure will become apparent to those skilled in the art to which the present disclosure relates upon reading the following description with reference to the accompanying drawings, in which:

[0009] Fig. 1 is a perspective view of a percutaneous tunneling device, in a disassembled configuration, constructed in accordance with one aspect of the present disclosure;

[0010] Fig. 2 is a schematic illustration showing the percutaneous tunneling device of Fig. 1 in an assembled configuration;

[0011] Fig. 3 is a front view of the percutaneous tunneling device in Fig. 2;

[0012] Fig. 4 is a process flow diagram illustrating a method for forming a

percutaneous tunnel in a target tissue of a subject according to another aspect of the present disclosure;

[0013] Fig. 5 is a schematic illustration showing the percutaneous tunneling device in Fig. 1 positioned adjacent the target tissue;

[0014] Fig. 6 is a schematic illustration showing the percutaneous tunneling device in Fig. 5 being inserted into the target tissue; [0015] Fig. 7 is a schematic illustration showing deflection of the percutaneous tunneling device in Fig. 6 during tunnel formation;

[0016] Fig. 8 is a schematic illustration showing a camera extending through the percutaneous tunneling device in Fig. 7; and

[0017] Fig. 9 is a schematic illustration showing an electrode being positioned within the tunnel via the percutaneous tunneling device in Fig. 8.

DETAILED DESCRIPTION

Definitions

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which the present disclosure pertains.

[0019] In the context of the present disclosure, the singular forms "a," "an" and "the" can include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," as used herein, can specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

[0020] As used herein, the term "and/or" can include any and all combinations of one or more of the associated listed items.

[0021] As used herein, phrases such as "between X and Y" and "between about X and Y" can be interpreted to include X and Y.

[0022] As used herein, phrases such as "between about X and Y" can mean

"between about X and about Y." [0023] As used herein, phrases such as "from about X to Y" can mean "from about X to about Y."

[0024] It will be understood that when an element is referred to as being "on," "attached" to, "connected" to, "coupled" with, "contacting," etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, "directly on," "directly attached" to, "directly connected" to, "directly coupled" with or "directly contacting" another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

[0025] Spatially relative terms, such as "under," "below," "lower," "over," "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms can encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features.

[0026] It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

Thus, a "first" element discussed below could also be termed a "second" element without departing from the teachings of the present disclosure. The sequence of operations (or steps) is not limited to the order presented in the claims or figures unless specifically indicated otherwise.

[0027] As used herein, the term "subject" can be used interchangeably with the term "patient" and refer to any warm-blooded organism including, but not limited to, human beings, pigs, rats, mice, dogs, goats, sheep, horses, monkeys, apes, farm animals, livestock, rabbits, cattle, etc.

[0028] As used herein, the term "target tissue" can refer to a desired portion of biological tissue {e.g., skin, muscle, bone, etc.) within or through which a tunnel can be formed.

[0029] As used herein, the term "in communication" can refer to at least a portion of a component, element, or structure being adjacent, in the general vicinity, in close proximity, and/or directly next to a second component, element, or structure.

Overview

[0030] The present disclosure relates generally to devices and methods for percutaneous surgical or medical procedures and, more particularly, to devices and methods that permit rapid, accurate, and safe percutaneous tissue dissection during various surgical or medical procedures. Advantageously, the present disclosure provides a percutaneous tunneling device for: (1 ) simplifying tunneling procedures {e.g., DBS lead installation procedures, etc.) by permitting rapid transfer of tissue dissection tools during tunnel formation; (2) preventing or minimizing complications {e.g., bleeding, pneumothorax, peritonitis, etc.) typically associated with percutaneous tunnel formation; (3) improved maneuvering and advancement through different tissues to avoid complex subject anatomy without comprising patient safety; and (4) decreasing the time needed to perform certain surgical and medical procedures.

Devices

[0031] One aspect of the present disclosure can include a percutaneous tunneling device 10 (Figs. 1 -2) for forming a tunnel 76 (Fig. 6) in a target tissue of a subject. As discussed in more detail below, the percutaneous tunneling device 10 (Fig. 1 ) can comprise a tunneler housing 12 configured to receive a stylet 14. The stylet 14 can be inserted into the tunneler housing 12 {e.g., during tunnel formation) and, upon tunnel formation, removed from the tunneler housing.

Tunneler Housing

[0032] In one aspect, the tunneler housing 12 can comprise a main tunneler housing body 16 having a distal end portion 18 spaced apart from a proximal end portion 20. The main tunneler housing body 16 can also include an inner surface 22 and an outer surface 24. The inner surface 22 can define an inner lumen 26 extending between the distal and proximal end portions 18 and 20. In some instances, the inner lumen 26 can be sized and dimensioned to receive the stylet 14 (or any other desired medical instrument, such as an endoscope, a camera, etc.). All or only a portion of the tunneler housing 12 can have a rigid, semi-rigid or flexible configuration. In one example, the tunneler housing 12 can have a flexible configuration to permit controlled flexion of the percutaneous tunneling device 10 during tunnel formation. The tunneler housing 12 can have a tubular shape; however, other shapes are possible. The tunneler housing 12 can be made from one or a combination of metals {e.g., aluminum, etc.) and/or non- metals {e.g., plastics, etc.). [0033] In another aspect, one or more light ports 28 can be located at the distal end portion 18 of the tunneler housing 12. The light port 28 can extend radially between the inner and outer surfaces 22 and 24 of the main tunneler housing body 16, and can define a light port lumen 30 that is in communication with the inner lumen 26. The light port lumen 30 can have a circular cross-sectional shape; however, other cross-sectional shapes are possible. During use of the percutaneous tunneling device 10, the light port 28 can convey light generated by a component of the stylet 14 through the light port lumen 30. Advantageously, this provides a device operator {e.g., a surgeon) with the ability to track the percutaneous tunneling device 10, but without the need for

cumbersome and expensive imaging equipment.

[0034] In another aspect, the proximal end portion 20 of the main tunneler housing body 16 can include a handle 32 operably connected thereto. The handle 32 can include a main handle body 34 having a distal handle end portion 36 spaced apart from a proximal handle end portion 38. As shown in Fig. 1 , the distal handle end portion 36 can be coupled to the proximal end portion 20 of the main tunneler housing body 16. In some instances, the handle 32 can include a handle lumen 40 that is coaxially aligned, and in fluid communication with, the inner lumen 26 of the tunneler housing 12. The handle lumen 40 can extend between the distal and proximal handle end portions 36 and 38 of the main handle body 34. In one example, the handle 32 can have a circular cross-sectional shape (or any other desired cross-sectional shape). The handle 32 can be made of the same material(s) or different material(s) used to form the tunneler housing 12. [0035] The handle 32 is rotatable about the tunneler housing 12, which causes flexion of the distal end portion 18 relative to the handle 32. For example, the handle 32 can be rotated about the proximal end portion 20 {e.g., clockwise or counterclockwise) to cause flexion of the distal end portion 18 relative to the handle 32. The handle 32 can be operably connected to the distal end portion 18 by a control mechanism {e.g., cables) (not shown). Advantageously, flexion of the distal end portion 18 relative to the handle 32 can allow a user to steer the percutaneous tunneling device 10 along a nonlinear path during tunnel formation.

Stylet

[0036] In another aspect, the stylet 14 of the percutaneous tunneling device 10 can be configured for insertion into the inner lumen 26 of the tunneler housing 12 (Figs. 1 -3). Advantageously, the stylet 14: (1 ) can accommodate multiple components or tools to facilitate tunnel formation; and (2) can be easily removed from the tunneler housing 12 to permit placement of relatively larger components or tools through the tunneler housing.

[0037] As shown in Fig. 1 , the stylet 14 can comprise a main stylet body 42 having a distal stylet end portion 44 spaced apart from a proximal stylet end portion 46. In some instances, the main stylet body 42 can be configured to be friction-fit with the inner lumen 26. Upon insertion of the stylet 14 into the inner lumen 26, the proximal stylet end portion 46 can be co-planar, or substantially co-planar, with the proximal handle end portion 38, and the distal stylet end portion 44 can be concentric with the distal end portion 18 of the tunneler housing 12 (Figs. 2-3). The stylet 14 can have a tubular shape; however, other shapes are possible {e.g., a shape substantially similar to the shape of the tunneler housing 12). The stylet 14 can be made from one or a combination of metals {e.g., aluminum, etc.) or non-metals {e.g., plastics, etc.). All or only a portion of the stylet 14 can have a rigid, semi-rigid or flexible configuration. For example, the stylet 14 can have a flexible configuration to permit controlled flexion of the distal stylet end portion 44.

[0038] In another aspect, the stylet 14 can include at least one light source 48 associated therewith. In some instances, the light source 48 can be an LED that extends through the stylet 14 and whose light emission portion is located at the distal stylet end portion 44. In other instances, the light source 48 can be located external to the stylet 14 {e.g., on a portion of the tunneler housing 12, on an apparatus located external to the percutaneous tunneling device 10, etc.). The light source 48 can provide light at the distal end portion 18 of the tunneler housing 12 during tunnel formation. For example, the light source 48 can be in communication with the light port lumen 30 of the tunneler housing 12 such that light emitted from the light source 48 is conveyed from the stylet 14 through the light port lumen 30. The light source 48 can also permit visualization of the target tissue during a surgical or medical procedure {e.g., where a camera or endoscope is used).

[0039] In another aspect, the stylet 14 can include a suction lumen 50 extending {e.g., longitudinally) between the distal and proximal stylet end portions 44 and 46. In some instances, the suction lumen 50 can be defined by a proximal suction lumen opening (not shown) located at the proximal stylet end portion 46, and a distal suction lumen opening 52 located at the distal stylet end portion 44. The suction lumen 50 can have a circular cross-sectional shape (or any other desired cross-sectional shape). In some instances, the suction lumen 50 is configured to receive a suction device (not shown) {e.g., medical tubing) for withdrawing dislodged tissue particulates.

Alternatively, a suction device {e.g., a pump) can be placed in communication with the suction lumen 50 at the proximal suction lumen opening so that suction is applied through the suction lumen.

[0040] In another aspect, the stylet 14 can include a working lumen 54 extending {e.g., longitudinally) between the distal and proximal stylet end portions 44 and 46. In some instances, the working lumen 54 can be defined by a proximal working lumen opening (not shown) at on the proximal stylet end portion 46, and a distal working lumen opening 56 located at the distal stylet end portion 44. As shown in Figs. 1 -3, the distal working lumen opening 56 can be spaced apart from the distal suction lumen opening 52. The working lumen 54 can be configured to receive one or more tissue dissection modalities (not shown), such as a gamma knife, a bone drill, a dermatome, a lancet, an electrocauterizer, an ultrasound probe, etc. The working lumen 54 can have a circular cross-sectional shape (or any other desired cross-sectional shape).

[0041] It will be appreciated that, in some instances, the stylet 14 can include only a single light source 48, only a single suction lumen 50, and only a single working lumen 54.

Methods

[0042] Another aspect of the present disclosure can include a method 58 (Fig. 4) for forming a tunnel in a target tissue. The method 58 can generally include the steps of: providing a percutaneous tunneling device 10 (Step 60); advancing at least one dissection modality through the percutaneous tunneling device (Step 62); inserting the percutaneous tunneling device into a target tissue (Step 64); advancing the percutaneous tunneling device through the target tissue (Step 66); optionally deflecting a portion of the percutaneous tunneling device 10 relative to the target tissue (Step 68); and performing a medical or surgical procedure (Step 70). It will be appreciated that the method 58 can find use in a variety of medical or surgical applications, such as in neurosurgery {e.g., DBS procedures, peripheral nerve stimulation, drug pump implantation, VP shunt procedures, etc.), plastic surgery procedures {e.g., breast augmentation, liposuction, etc.), general surgery, and the like.

[0043] At Step 60, a percutaneous tunneling device 10 can be provided. In some instances, the percutaneous tunneling device 10 can be configured as shown in Fig. 1 and described above. For example, the percutaneous tunneling device 10 can comprise a tunneler housing 12 and a stylet 14 installed within an inner lumen 26 of the tunneler housing 12. It will be appreciated that the particular dimensions of the percutaneous tunneling device 10 will depend upon the particular medical or surgical procedure.

[0044] At Step 62, at least one dissection modality 72 can be advanced through the working lumen 54. In some instances, the at least one dissection modality 72 can include a first dissection modality 72a for cutting tissue {e.g., a gamma knife, a bone drill, a dermatome, a lancet, etc.), and a second dissection modality 72b for cauterizing tissue {e.g., an electrocauterizer, an ultrasound probe, etc.). In one example, the first and second dissection modalities 72a and 72b can be simultaneously advanced through the working lumen 54 for ultimate deployment beyond the distal end portion 18 of the tunneler housing 12. In another example, the first and second dissection modalities 72a and 72b can be sequentially advanced through the working lumen 54 for ultimate deployment beyond the distal end portion 18 of the tunneler housing 12. The first and second dissection modalities 72a and 72b can be deployed beyond the distal end portion 18 of the tunneler housing 12 after the percutaneous tunneling device 10 is placed into contact with a target tissue 74 (Fig. 5).

[0045] At Step 64, the percutaneous tunneling device 10 can be inserted into the target tissue 74. As shown in Fig. 6, the distal end portion 18 of the tunneler housing 12 can be placed into contact with {e.g., pierce) the target tissue 74. The first and second dissection modalities 72a and 72b can be activated and then advanced ahead of the tunneler housing 12 into the target tissue 74. In one example, the first and second dissection modalities 72a and 72b can be activated and advanced to simultaneously cut and cauterize the target tissue 74 as the percutaneous tunneling device 10 is inserted into the target tissue.

[0046] At Step 66, the percutaneous tunneling device 10 can be advanced through the target tissue 74. As the percutaneous tunneling device 10 is advanced through the target tissue 74 (Fig. 6), the outer surface 24 of the tunneler housing 12 can displace the cut and cauterized portion of the target tissue 74 to form a tunnel 76 though the target tissue. As the percutaneous tunneling device 10 is urged though the target tissue 74, the light source 48 can be activated to emit light, which is then conveyed through the light port lumen 30. The conveyed light advantageously allows visualization of the distal end portion 18 of the tunneler housing 12 through the skin of the patient. In some instances, a suction device 78 can be advanced through the suction lumen 50 and out of the distal suction lumen opening 52 to withdraw dislodged tissue particulates as the percutaneous tunneling device 10 is advanced through the target tissue 74.

[0047] At Step 68, the percutaneous tunneling device 10 can optionally be deflected relative to the tunneler housing 12 to change the trajectory of the distal end portion 18 of the tunneler housing 12 and thus the tunnel 76 (Fig. 7) to avoid tunneling through certain tissue structures {e.g., one or more organs) or to reach a target surgical location. To do so, the handle 32 can be rotated about the tunneler housing 12 so that the distal stylet end portion 44 and the distal end portion 18 of the tunneler housing 12 are each deflected relative to the tunneler housing 12.

[0048] At Step 70, the percutaneous tunneling device 10 can be used for performing a medical or surgical procedure. In some instances, once the tunnel 76 has been formed, the stylet 14 can be removed from the inner lumen 26 while the tunneler housing 12 remains in the tunnel 76. In one example, a camera 80 (Fig. 8) can then be advanced through the tunneler housing 12 and into the tunnel 76 to visualize the tunnel. After visualizing the tunnel 76, the camera 80 can be removed from the inner lumen 26 and the stylet 14 can be re-installed into the inner lumen. The percutaneous tunneling device 10 can then be urged further into the target tissue 74 to enlarge the tunnel 76.

[0049] In another example, the camera 80 can be used to visualize a desired location for installing an electrode 82 (Fig. 9) (or another other suitable implant, such as a stent, a screw, etc.) within the tunnel 76. For instance, the electrode 82 can be advanced through the inner lumen 26 and into the tunnel 76. The electrode 82 can then be installed within the tunnel 76 in any suitable manner {e.g., a friction-fit, sutures, etc.). Once the electrode 82 is installed within the tunnel 76, the tunneler housing 12 can be removed from the tunnel to complete the medical or surgical procedure.

[0050] From the above description of the present disclosure, those skilled in the art will perceive improvements, changes, and modifications. Such improvements, changes, and/or modifications are within the skill of the art and are intended to be covered by the appended claims.

Claims

The following is claimed:

1 . A percutaneous tunneling device comprising:

a tunneler housing having an inner lumen extending longitudinally through the tunneler housing; and

a removable stylet disposed within the inner lumen, the stylet including: at least one light source;

at least one suction lumen extending longitudinally through the stylet; and

at least one working lumen extending longitudinally through the stylet and being configured to receive at least one tissue dissection modality.

2. The percutaneous tunneling device of claim 1 , further comprising a handle coupled to a proximal end of the tunneler housing;

wherein rotation of the handle about the tunneler housing deflects a distal end of the tunneler housing relative to the handle.

3. The percutaneous tunneling device of claim 2, further comprising at least one light port located at the distal end of the tunneler housing, the at least one light port for conveying light generated by the at least one light source.

4. The percutaneous tunneling device of claim 1 , wherein the at least one working lumen is configured to simultaneously receive at least one first tissue dissection modality for cutting a target tissue and at least one second tissue dissection modality for cauterizing the target tissue.

5. The percutaneous tunneling device of claim 1 , further comprising a camera configured for advancement through the inner lumen of the tunneler housing upon removal of the stylet.

6. A percutaneous tunneling device consisting of:

a removable stylet disposed within the inner lumen, the stylet including: a light source;

a suction lumen extending longitudinally through the stylet; and a working lumen extending longitudinally through the stylet and being configured to receive at least one tissue dissection modality.

7. The percutaneous tunneling device of claim 6, further comprising a handle coupled to a proximal end of the tunneler housing;

8. The percutaneous tunneling device of claim 7, further comprising at least one light port located at the distal end of the tunneler housing, the at least one light port for conveying light generated by the light source.

9. The percutaneous tunneling device of claim 1 , wherein the working lumen is configured to simultaneously receive at least one first tissue dissection modality for cutting a target tissue and at least one second tissue dissection modality for cauterizing the target tissue.

10. The percutaneous tunneling device of claim 6, further comprising a camera configured for advancement through the inner lumen of the tunneler housing upon removal of the stylet.

1 1 . A method for forming a tunnel in a target tissue of a subject, the method comprising the steps of:

providing a percutaneous tunneling device that comprises:

a removable stylet disposed within the inner lumen, the stylet including:

at least one light source;

at least one suction lumen extending longitudinally through the stylet; and

at least one working lumen extending longitudinally through the stylet and being configured to receive at least one tissue dissection modality; and actuating the at least one tissue dissection modality, while advancing the tunneler housing through the target tissue, to simultaneously cut and cauterize the target tissue and thereby form the tunnel in the target tissue.

12. The method of claim 1 1 , wherein the step of providing a percutaneous tunneling device further comprises the steps of:

providing the tunneler housing with a handle coupled to a proximal end thereof; and

rotating the handle about the tunneler housing to deflect a distal end of the tunneler housing relative to the handle.

13. The method of claim 1 1 , wherein the step of providing a percutaneous tunneling device further comprises the step of:

positioning the stylet in the inner lumen such that a distal end portion of the stylet is concentric with a distal end of the tunneler housing.

14. The method of claim 1 1 , wherein the step of actuating the at least one tissue dissection modality further comprises the steps of:

providing at least one first tissue dissection modality and at least one second tissue dissection modality;

simultaneously advancing the at least one first tissue dissection modality and the at least one second tissue dissection modality through the at least one working lumen; operating the at least one first tissue dissection modality to cut the target tissue; and

operating the at least one second tissue dissection modality to cauterize the target tissue.

15. The method of claim 1 1 , wherein the step of actuating the at least one dissection modality further comprises the step of:

withdrawing dislodged tissue particles through the at least one suction lumen.

16. The method of claim 1 1 , further comprising the steps of:

advancing a camera through the inner lumen of the tunneler housing upon removal of the stylet; and

visualizing the target tissue with the camera.

17. The method of claim 1 1 , further comprising the steps of:

providing the tunneler housing with at least one light port located at a distal end of the tunneler housing;

actuating the at least one light source; and

determining the location of the distal end of the tunneler housing via the at least one light port while the tunneler housing is advanced through the target tissue.

18. The method of claim 1 1 , further comprising the steps of: removing the stylet from the inner lumen after the tunnel is formed in the target tissue; and

advancing at least one electrode through the inner lumen into the tunnel.