Medical tools and methods for gaining access to the extravascular space

Abstract

In some instances, a tool is described that is used, for example, to create a substernal tunnel in a patient or for other purposes. The tool may include a handle and a tunneling shaft that is coupled to the handle. The tunneling shaft extends from a proximal end to a distal end, and at least a portion of the tunneling shaft extends in a curved direction between a first end and the distal end. The distal end of the tunneling shaft includes a cutting tool with a sharp edge. The cutting tool can be moved from a recessed position, in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft, to an expanded position, in which the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft, to, for example, cut pericardium, scar tissue, and / or connective tissue with the sharp edge.

Description

Technical Field

[0001] The present disclosure relates to tools and associated methods for safely gaining access to a space within a patient's body, and more particularly to tools and associated methods suitable for safely gaining access to a substernal or other extravascular space for positioning a medical device therein. Background Art

[0002] Some medical procedures may include passing through multiple tissue layers to obtain access to a position within the patient's body. Such medical procedures may include implanting one or more medical devices or components thereof, such as medical electrical leads, at the position. One way to enter the intrathoracic position is under the sternum, and includes crossing one or more tissue layers, such as a diaphragm attachment that connects the diaphragm to the sternum. An example of a procedure is implanting the distal portion of one or more leads under the sternum, and may include using an implantation tool to enter the cavity within the patient's chest. One or more leads may be part of an implantable cardiac defibrillator (ICD) system that may be used to deliver high-energy electrical pulses to the patient's heart to terminate life-threatening cardiac arrhythmias, such as ventricular fibrillation. Such an ICD may include or may be part of a system that includes a subcutaneously implantable housing that surrounds a pulse generator or other electronic device of the ICD. The housing of some ICDs may be connected to one or more leads that may be configured to deliver defibrillation and / or pacing pulses. Summary of the invention

[0003] The present disclosure provides tools for obtaining access to a gap in a patient's body and implanting a medical device or its components into the gap (e.g., implanting a lead into an extravascular space) and implantation techniques using such tools. In one example, the present disclosure provides a tool for creating a substernal tunnel in a patient's body. The tool includes: a handle; and a tunneling shaft connected to the handle, wherein the tunneling shaft extends from a proximal end to a distal end, and at least a portion of the tunneling shaft extends in a curved direction between a first end and the distal end, wherein the distal end of the tunneling shaft includes a cutting tool with a sharp edge, the cutting tool being able to move from a recessed position to an expanded position, in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft, and in the expanded position, the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft.

[0004] In another example, the present disclosure relates to a method for creating a tunnel in a patient, for example, using a tool. The method includes inserting a distal portion of a tool into the patient through an incision in the patient, wherein the tool includes a handle, and a tunneling shaft coupled to the handle, wherein the tunneling shaft extends from a proximal end to a distal end, and at least a portion of the tunneling shaft extends in a curved orientation between a first end and the distal end, wherein the distal end of the tunneling shaft includes a cutting tool having a sharp edge, the cutting tool being movable from a recessed position, wherein the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft, to an expanded position, wherein the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft, and when the distal portion of the tool is inserted into the patient through the incision, expanding the cutting tool from the recessed position to the expanded position to cut tissue of the patient using the sharp edge of the cutting tool.

[0005] The present disclosure is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the systems, devices, and methods described in detail in the following drawings and descriptions. Additional details of one or more examples are set forth in the following drawings and descriptions. Other features, objects, and advantages will become apparent from the description and drawings and statements provided below. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The following drawings are illustrative of examples and do not limit the scope of the present invention. The drawings are not drawn to scale (unless otherwise specified) and are intended to be used in conjunction with the explanations in the following detailed description. The examples will be described below in conjunction with the drawings, in which the same reference numerals represent the same elements.

[0007] Figure 1A -B is a schematic illustration showing an exemplary extravascular implant.

[0008] Figure 2 is a schematic illustration used to describe the substernal approach.

[0009] Figure 3-6 is a schematic diagram showing an example tunneling tool according to an example of the present disclosure.

[0010] Figures 7A-7C is a schematic diagram showing a distal portion of another example tunneling tool according to examples of the present disclosure.

[0011] Fig. 8A and 8B is a schematic diagram showing a distal portion of another example tunneling tool according to examples of the present disclosure.

[0012] Fig.9A and 9B is a schematic diagram showing a distal portion of another example tunneling tool according to examples of the present disclosure.

[0013] Figures 10A-10C is a schematic diagram showing a distal portion of another example tunneling tool according to examples of the present disclosure.

[0014] Figures 11A-11C is a schematic diagram showing another example tunneling tool according to examples of the present disclosure.

[0015] Fig.12 is a schematic diagram showing another example tunneling tool according to examples of the present disclosure.

[0016] Fig.13A and 13B is a schematic diagram showing another example tunneling tool according to examples of the present disclosure.

[0017] Fig.14 is a schematic diagram showing another example tunneling tool according to examples of the present disclosure.

[0018] Figures 15A-15C is a schematic diagram showing another example tunneling tool according to examples of the present disclosure.

[0019] Figures 16A-16E is a schematic diagram showing another example tunneling tool according to examples of the present disclosure.

[0020] Fig.17 is a schematic diagram showing a distal portion of another example tunneling tool according to examples of the present disclosure.

[0021] Figures 18A-18D It is a depiction Figure 3 Schematic illustration of a tool being advanced upwardly beneath a patient's sternum, according to some examples.

[0022] Fig.19 is possible with, for example, Figure 3 Conceptual illustration of an example introducer sheath for use in conjunction with a tunneling tool.

[0023] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will become apparent from the description and drawings, and from the claims. DETAILED DESCRIPTION

[0024] The following specific embodiments are exemplary in nature and are not intended to limit the scope, applicability or configuration of the tools and techniques described in this disclosure in any way. Instead, the following embodiments provide practical examples, and those skilled in the art will recognize that some of the examples may have suitable alternatives.

[0025] Figure 1A -B is a schematic illustration of an exemplary extravascular implant of an exemplary system 10, the exemplary system comprising a pulse generator 14 and an implantable medical electrical lead 16 coupled thereto. The pulse generator 14 is shown as being implanted in the left mid-axilla of the patient 12, superficially subcutaneously above the thorax of the patient. The pulse generator 14, which can be configured to provide cardiac pacing and / or defibrillation therapy, comprises an airtightly sealed housing in which suitable electronics and a power source are contained, and the airtightly sealed housing is formed of a conductive material such as titanium or a combination of conductive and non-conductive materials. The pulse generator 14 further comprises a connector module by means of which the lead 16 is electrically coupled to the electronics contained therein via, for example, electrical contacts contained in the connector module and an airtightly sealed feedthrough assembly as known in the art. The conductive material of the device housing can be used as electrodes, for example, to provide the aforementioned therapy in combination with one or more pacing / sensing electrodes 22, 26 and / or defibrillation electrodes 24, 28 of lead 16, which is shown as being implanted in the substernal space 3 within, for example, the loose connective tissue of the anterior mediastinum and / or the substernal muscle tissue.

[0026] Lead 16 can have any of a variety of configurations. For example, lead 16 can include more or fewer pacing / sensing electrodes. In another example, lead 16 can include more or less than two defibrillation electrodes 24, 28 and / or have one or more defibrillation electrodes formed from multiple segments. Examples of leads with multiple defibrillation electrodes and / or segments are described in commonly assigned co-pending U.S. Patent Publication No. 2015 / 0306375 (Marshall et al.), U.S. Patent Publication No. 2015 / 0306410 (Marshall et al.), and U.S. Patent Publication No. 2016 / 0158567 (Marshall et al.).

[0027] Reference Figure 1B , the substernal space 3 can be viewed as being bounded laterally by the pleura 39 surrounding the patient's lungs, posteriorly by the pericardial sac 15 surrounding the patient's heart 6, and anteriorly by the sternum 13. In some cases, the anterior wall of the anterior mediastinum may also be formed by the transverse thoracic muscle and one or more costal cartilages. Although Figure 1A and 1BThe present invention is described in the context of placing the distal portion of lead 16 in the substernal space 3, but in other examples, the tools and implantation techniques described herein can be used to implant the distal portion of lead 16 at other locations outside the heart. In one example, the tools can be used to place the distal portion of lead 16 in the pericardium via a percutaneous subxiphoid approach. In some examples, the tools and implantation techniques described herein can be used to implant other medical devices or components thereof and / or for other spaces in a patient's body, such as implanting a leadless pacemaker on or near the outside of the heart via a substernal approach.

[0028] Figure 2 1 is a schematic illustration showing an access site A for forming a passage between the diaphragm 19 of a patient and the xiphoid process 20 of the sternum 13, for example, to create a substernal tunnel for positioning a medical device such as a medical electrical lead 16 therein. After making a superficial incision, an operator using an appropriate tunneling tool can open a passage between the diaphragm attachment 18 and the diaphragm 19, for example, by blunt and / or sharp dissection, wherein the operator can employ a tunneling tool, such as those example tools described herein, to create a passage, and then form a substernal tunnel (e.g., along the sternum). Figure 2 Because the bony structure of the sternum inhibits external palpation, the operator must be extremely careful during dissection (e.g., blunt and / or sharp) and / or tunneling to avoid damaging the substernal structures or the thoracic cavity, which could damage the pleura 6 of the lungs or the heart. The tools and associated methods disclosed herein are configured to help the operator obtain a desired substernal approach in a controlled manner that mitigates the risk of injury to body organs and create clearance for positioning a medical device such as a medical electrical lead 16 therein.

[0029] In some instances, the distal portion of lead 16 can be implanted to be positioned between the posterior sternum 13 and the anterior wall of the heart 6. The implantation procedure can be performed using a blunt trocar with a flexible port to create a small tunnel near the posterior aspect of the sternum 13 through an entry point into the body located near the xiphoid process 20. The distal portion of lead 16, such as the portion of lead 16 carrying some or all of electrodes 22, 24, 26, 28, is then placed in the anterior mediastinum. The proximal end of lead 16 is then tunneled subcutaneously or submuscularly to the left mid-axillary position of the pulse generator 14 and connected to the pulse generator. The pulse generator 14 and lead 16 are capable of providing, for example, defibrillation, anti-tachycardia pacing (ATP), bradycardia pacing, post-shock pacing, and cardiac arrest "lifeboat pacing."

[0030] The lead 16 can be implanted in the patient 12 using a suitable tunneling tool with a blunt trocar. However, patients who have previously undergone a median sternotomy often have extensive scar tissue, and the pericardium is often adhered to the posterior sternum. This scar tissue makes it very challenging, and in some cases, it is relatively undesirable for a blunt trocar to create a small tunnel in the anterior mediastinum. The surgeon may not want to enter the substernal space of such patients unless he can directly view the location. Therefore, patients who have previously undergone one or more median sternotomies may be less likely to receive an extravascular ICD or other medical device that includes implanting the distal portion of the lead 16 between the posterior sternum 13 and the anterior wall of the heart 6 in the manner described above.

[0031] According to some examples of the present disclosure, a tunneling tool (or trocar) is described that allows a forward, hemispherical view and selectively cuts (e.g., can be selected between blunt and sharp cuts) tissue while tunneling through diaphragmatic attachments, pericardial adhesions, and other soft tissues. Examples include tunneling tools that have a knife blade or other cutting tool with a sharp edge, for example, on the distal end of the tool, for entering the substernal space, cutting adhesions, and creating a working chamber in, for example, the thoracic cavity. Such tunneling tools may also include an optical window for allowing a surgeon or other user, for example, to view the movement of the distal end of the tunneling tool through the tissue using an endoscope inserted into the tunneling tool. This viewing can provide better guidance for the tunneling tool during the implantation procedure, and allows the clinician to identify the location where the cutting tool may be expected to be deployed, for example, to cut tissue near the distal end of the tunneling tool using sharp cutting rather than blunt cutting.

[0032] Examples of the present disclosure can provide a tool that allows blunt dissection / tunneling and transection of adhesions under direct visualization. This tool allows safe placement of an extravascular ICD even in patients who have previously undergone a sternotomy. An optical window with an integrated knife or other cutting blade can allow easy identification of tissue prior to dissection during a tunneling procedure. Examples of the present disclosure can also allow easier access to the chest of a patient who has previously undergone a sternotomy for coronary artery bypass grafting (CABG) or valve replacement. The example tool can allow for reduction of pericardial adhesions to create a working gap for placement, adjustment, and removal of leads.

[0033] Figure 3-6 1 is a schematic diagram illustrating the functionality of an example tunneling tool 30 for gaining substernal access into a patient's body and creating a substernal tunnel, according to some examples. Figure 3 A tunneling tool 30 is shown, comprising a tunneling shaft 32 and a handle 34 . Figure 4 Demonstrates tunneling axis 32 around Figure 3 A cross-sectional view of the cross section AA is shown. Figure 5A and 5B The distal end 38 of the tunneling shaft 32 is shown. Figure 6 A cross-sectional view of the handle 34 is shown.

[0034] like Figure 3 As shown, the tunneling shaft 32 of the tunneling tool 30 extends from a proximal end 36 to a distal end 38 (or "distal tip 38"). The tool 30 also includes a handle 34, which is shown as being coupled to the proximal end 36 of the tunneling shaft 32. As opposed to extending from the proximal end 36 to the distal end 38 in a linear or straight manner, at least a portion of the tunneling shaft 32 extends from the proximal end 36 to the distal end 38 in a curved orientation, for example, relative to an axis 40. The axis 40 may be defined by a central longitudinal axis of the handle 34, or may be defined by a portion of the shaft 32 that initially extends from the handle 34 in a generally straight manner and then exhibits a curved orientation beginning at a point between the proximal end 36 and the distal end 38 of the shaft 32. The curved orientation of the tunneling shaft 32 results in Figure 3 32A between the distal end 38 and the axis 40 shown in FIG. The offset 32A may range from about 0.35 inches to about 1.25 inches, such as about 0.720 inches, but other examples are contemplated. In some cases, the curvature of the tunneling shaft 32 may be maintained during the tunneling procedure with the path of the distal tip close to the posterior side of the sternum and away from vital organs such as the lungs or heart.

[0035] In some examples, tunneling shaft 32 is curved about its entire length from proximal end 36 to distal end 38 (e.g., as shown in FIG. Figure 3 32 ), or may include one or more sections that are substantially straight and one or more other sections that are curved. For example, a proximal portion of the tunneling shaft 32 that extends directly from the handle 34 may be substantially straight for some of the length of the tunneling shaft 32, and then transition to a curved, more distal portion of the tunneling shaft 32. In some examples, the curved portion of the tunneling shaft exhibits a radius of curvature of about 15 inches to about 40 inches.

[0036] The tunnel axis 32 is Figure 4-6, can be tubular, for example, with a circular or elliptical outer profile and / or define one or more inner lumens. Any suitable material can be used for the tunneling shaft 32, for example, metal (stainless steel, coated steel, titanium alloy, aluminum alloy, etc.) and plastic (for strength and rigidity, unfilled and filled with suitable fibers such as glass or carbon) can be used. Suitable plastic materials include but are not limited to acetal copolymers, polytetrafluoroethylene (PTFE) (e.g., TEFLON), polyetheretherketone (PEEK), polyphenylsulfone (PPSU) (e.g., RADEL) and polycarbonate. In some instances, the tunneling shaft 32 can be formed by a material that allows all or at least a portion of the tunneling shaft 32 to be transparent along the length of the shaft 32. The shaft 32 can be substantially rigid, so that the clinician can accurately control the positioning of the tip relative to the vital organs through the optical window 44 under the visualization provided by fluoroscopy or other techniques. To this end, in some instances, the tip of the shaft 32 preferably has at least some metal components (e.g., metal blades), which will allow viewing using appropriate medical imaging techniques.

[0037] In some instances, the stiffness of the shaft 32 can be described in the context of possible forces that can act on the shaft 32 during, for example, an implantation procedure. As an example, there can be a force that an operator can apply to keep the shaft 32 (e.g., distal end 38) pressed against the sternum 13 of the patient 12. The stiffness of the shaft 32 can be such that the shaft 32 does not flex significantly when the operator biases the shaft 32 upward / forward. In some instances, when the operator biases the shaft 32 upward / forward, the shaft 32 may be moved downward. Figure 3 When a force greater than about 5 pounds is applied to the distal end 38 in the direction 37 shown, the shaft 32 exhibits substantially no deflection. Figure 3 When a force greater than about 5 pounds is applied to the distal end 38 in the direction 37 shown, the shaft 32 will not "stuck" (eg, still allow the cutting tool 50 to be deployed and / or allow viewing through the optical window 44).

[0038] Another example force that may act on the shaft 32 is the torque on the shaft 32 when the operator attempts to keep the shaft 32 aligned during insertion. If the operator rotates the shaft 32 back and forth along the axis 40, the shaft 32 must have substantial stiffness to sweep back and forth across the posterior side of the sternum 13, clearing adhesions, and still "excite" with a torque on the order of about 5 inch*lbs without getting stuck (e.g., still allowing the cutting tool 50 to deploy).

[0039] The tunneling shaft 32 may exhibit any suitable shape and size. Figure 4The tunneling shaft 32 is shown to have a substantially circular cross section, but other example cross-sectional shapes are contemplated. For example, as further described below, in some instances, the tunneling shaft 32 can exhibit an elliptical cross section. The outer diameter (in the case of a circular cross section) or the maximum outer dimension (in the case of a non-circular cross section) of the tunneling shaft 32 can range from about 3 millimeters (mm) to about 15 mm, but other instances are contemplated. The length of the tunneling shaft 32 from the proximal end 36 directly adjacent to the handle 34 to the distal end 38 can range from about 4 inches to about 12 inches, but other instances are contemplated. In instances where a portion of the shaft 32 is substantially straight from the proximal end 36 located near the handle, and then converted to a curved portion at a point between the proximal end 36 and the distal end 38, approximately 1 / 3 (one third) of the length outside the proximal end 36 of the shaft 32 can be substantially straight. In some instances, the length of the substantially straight portion of the shaft 32 can be from about 0.5 inches to about 1.5 inches (e.g., when the total length of the shaft 32 is about 4 inches). In some examples, the length of the generally straight portion of the shaft 32 can be about 3 inches to about 5 inches (e.g., where the total length of the shaft 32 is about 12 inches). In some examples, about 2 / 3 (two-thirds) of the total length of the shaft 32 beyond the proximal end 36 can be generally straight. In some examples, the length of the generally straight portion of the shaft 32 can be about 7 inches to about 9 inches (e.g., where the total length of the shaft 32 is about 12 inches).

[0040] The tunneling shaft 32 defines an inner lumen 46 extending from the proximal end 36 to the distal end 38. Figure 6 As shown, the inner lumen 46 extends from the tunneling shaft 32 through the handle 34, terminating at a proximal opening 48 of the handle. The distal end 38 of the tunneling tool 32 also includes an optical window 44 that is shaped to allow blunt dissection when tunneling through the tissue of the patient 12, such as using one or more of the techniques described herein. Figure 3-6 In the example of the embodiment of the present invention, the optical window 44 has a dome shape for the front edge to allow blunt dissection. However, other shapes are contemplated. The optical window 44 can be formed of a transparent material, such as glass, quartz, or a transparent plastic such as polycarbonate (e.g., LEXAN) or acrylic. During the implantation procedure, an endoscope or other optical tool can be inserted into the lumen 46 through the proximal opening 48 in the handle 34 and advanced through the lumen 46 to the distal end 38 of the tunneling tool 32 adjacent to the optical window 44. In this way, the surgeon or other user can view the path of the distal end 38 while advancing through the tissue of the patient 12 during insertion of the tunneling tool 32 into the patient 12.

[0041] In addition, if Figure 5A and 5BAs shown, tunneling tool 30 includes a cutting tool 50 located at distal end 38. Cutting tool 50 can take the form of a knife blade, scalpel blade, or other tool having a sharp edge 51 that is configured to cut through tissue, such as scar tissue, of patient 12 to a target location as tool 30 tunnels through substernal space 3 of patient 12. Cutting tool 50 can be configured to be positioned by a surgeon or other user from a recessed position (such as Figure 5A ) is selectively actuated to a deployed position (as shown) Figure 5B ). When the cutting tool 50 is in the recessed position, the lead edge or cutting edge of the cutting tool 50 is recessed into the distal end 38 of the shaft so that the outer surface of the optical window 44 defines the leading edge of the tool, thereby allowing blunt dissection of tissue while the tunneling shaft 32 is advanced in the substernal space of the tissue. Conversely, when the cutting tool 50 is in the deployed position, the cutting tool 50 defines the leading edge of the tunneling shaft 32, thereby allowing tissue such as scar tissue to be cut by the tool by sharp dissection rather than blunt dissection.

[0042] Any suitable mechanism may be utilized to allow the cutting tool 50 to be positioned in the recessed position ( Figure 5A ) and expansion positioning (such as Figure 5B For example, Figure 3 , 4 6, the tunneling shaft 32 includes blade arms 54A and 54B (collectively referred to as "blade arms 54") parallel to the plane of the leading edge 51 of the cutting tool 50 within the tunneling shaft 32, the blade arms being coupled to the cutting tool 50 at the distal end and extending rearwardly to the handle 34. The blade arms 54 may be located within the tunneling shaft 32, inside the inner lumen 46 and near the inner wall of the tunneling shaft 32 and / or near the outer surface of the tunneling shaft 32 (e.g., recessed into a track in the tunneling shaft 32). In instances where the blade arms 54 are positioned adjacent to the outer surface of the tunneling shaft 32 (e.g., within a recessed track), the tunneling tool 30 may include an outer sheath, such as a thin shrink wrap, that helps secure the blade arms in place relative to the tunneling shaft 32.

[0043] The blade arm 54 is mechanically coupled to the handle 34 so that actuation of the trigger 56 translates the blade arm 54 along the curved axis 32 toward the distal end 38 of the tool 30 to transfer mechanical energy to the cutting tool 50 to actuate the cutting tool 50 from the recessed position to the deployed position. In the deployed position, the sharp / front edge 51 of the cutting tool 50 can extend about 0.25 mm to about 2 mm beyond the distal end 38 of the tunneling axis 32. In other words, in the deployed position, when the cutting tool 50 is in the recessed position, the sharp / front edge 51 of the cutting tool 50 can extend beyond the leading edge of the distal end 38, e.g., about 0.25 mm to about 2 mm of the outer surface of the optical window 44.

[0044] In some instances, the pressing (pulling) of trigger 58 actuates cutting tool 50 from recessed positioning to deployed positioning, and cutting tool 50 can remain in deployed positioning before trigger 58 releases. Alternatively, tunneling member 30 can be configured to actuate trigger 56, for example, the pressing or pressing and releasing of trigger 56 can cause cutting tool 50 to actuate to deployed positioning from recessed positioning, and then for example, automatically returns to recessed positioning after cutting tool 50 advances forward a preset distance. In some instances, surgeon or other user, when pressing trigger 56 to control the length of tissue cut by cutting tool 50, can keep handle 34 of tool 30 static, described length approximately corresponds to when pressing trigger 56 to move cutting tool 50 to deployed positioning, the sharpness / front edge 51 of cutting tool 50 extends to the length beyond distal end 38. Alternatively or in addition, the surgeon or other user may advance the tunneling shaft 32 forward via the handle 34 while maintaining the cutting tool 50 in the deployed position, wherein the length of tissue dissection performed by the cutting tool 50 generally corresponds to the length by which the tunneling shaft 32 is advanced under the control of the surgeon or other user.

[0045] As an example, in Figure 6 In the configuration shown in FIG. 5 , the drive arm 54 is connected to a spring / hammer / bushing mechanism in the handle 34, which contains a mirror retaining slot 58, a hammer 60, a blade bushing 62, and a bushing stop 64. When the trigger 56 is pulled, the hammer 60 is retracted against the spring 66. The trigger 56 has a cantilever beam 56A with a hook. The hook engages with the hammer 60 and drives it against the spring 66. The beam 56A also has a post 56B that interacts with a slot in the wall of the handle body (not shown). When the trigger 56B is fully advanced, the pin 56B guided by the slot raises the hook and releases the hammer 60. After release, the hammer 60 springs forward, striking the blade bushing 60 to transfer mechanical energy to the blade drive arm 54 until it strikes a stop point defined by the bushing hard stop 64. The bushing hard stop 64 in the handle 34 prevents the blade bushing 62 from being advanced beyond the distal end 38 of the tunneling shaft 32 from the cutting tool 50 by a safe distance.

[0046] During a procedure for gaining substernal access into a patient and creating a substernal tunnel, e.g., for implanting a medical device such as a lead 16, the tunneling shaft 32 can be inserted into an inner lumen of an introducer sheath, e.g., wherein the sheath is sized to extend from a substantially distal end 38 to a substantially proximal end 36 of the tool shaft 32 prior to inserting and advancing the tunneling shaft 32 into the patient 12. An example of an introducer sheath 41 is shown in FIG. Fig.19. The sheath 41 includes a body 43 and a handle 45. The body 43 of the sheath 41 defines an inner passage. In one example, the sheath 41 can be an open sheath as shown and described in U.S. Patent Application No. 14 / 196,298 and U.S. Patent Application No. 14 / 196,443, both of which are incorporated herein by reference in their entirety. In the case of an open sheath, the sheath 41 can include an opening along the length of the body 43, and the inner passage can be entered through the opening anywhere along the length of the body 43. In another example, the sheath 41 can be a split sheath, wherein the body 43 includes a notch or other weakened portion for allowing the body 43 to split, as shown and described in further detail in U.S. Patent Application No. 14 / 196,443 previously incorporated above. In yet another example, the sheath 41 can be a sheath without any voids or scores on the body 43, in which case the sheath 41 can be removed by slitting the sheath using a cutter, as shown and described in U.S. Patent Application No. 14 / 196,443 previously incorporated above. The sheath 41 can have the other properties described above with reference to U.S. Patent Application Nos. 14 / 196,298 and 14 / 196,443 or any commercially available sheath.

[0047] The distal portion of the introducer sheath 41 can have an open end so as not to obstruct the view through the optical window 44 and the deployment of the cutting tool 50 at the distal end 38 of the tunneling shaft 32. Moreover, the open end allows the lead to be inserted into the target area. Once the tunneling shaft 32 is inserted into the introducer sheath 41, the distal end 38 can be inserted into the incision site, such as at the entry site A, and then tunneled upward to form a channel and then form a substernal tunnel (e.g., along the sternum). Figure 2During tunneling, the surgeon or other operator can control the advancement and direction of the tunneling shaft 32 by grasping the handle 34 positioned outside the patient's body. The surgeon or other operator can view the path of the distal end 38 of the tunneling shaft 32 during the procedure by using an optical window 44 of an endoscope or other viewing device inserted into the inner lumen 46 of the shaft 32. The surgeon or other operator can use the distal end 38 of the tunneling shaft to tunnel through the tissue of the patient 12 by blunt dissection with the cutting tool in a recessed position. The surgeon or other operator can also selectively deploy the cutting tool 50, for example, to cut scar tissue or other areas where blunt dissection does not allow the tunneling tool shaft 32 (for example, through the distal end 38 when the cutting tool 50 is recessed). Then, for example, the tunneling shaft 32 of the tool 30 is withdrawn from the patient's body, leaving the introducer sheath 41 in the substernal tunnel. The operator can pass a medical device such as the lead 16 described above through the inner lumen of the sheath through the proximal opening of the introducer sheath. The surgeon or other operator may then, according to some examples and methods, remove the introducer sheath 41 from the body, leaving the lead 16 within the substernal tunnel, and then remove the sheath from the lead, such as by cutting or splitting the introducer sheath away from the surrounding lead.

[0048] Figures 18A-18D is a conceptual diagram illustrating advancement of tunneling tool 30 during an example tunneling technique according to the present disclosure to insert at least a portion of shaft 32 into the substernal space beneath sternum 13. As described herein, a surgeon or other operator can selectively expand or retract cutting tool 50 at distal end 38 of tunneling shaft 32 as desired during the tunneling procedure, and view the tissue space through optical window 44 during the procedure.

[0049] like Fig.18A As shown, the distal portion of the tunneling shaft passes through the incision site, e.g. Figure 2 , wherein the cutting tool 50 is located in a recessed position at the distal end 38 of the tunneling shaft 32, wherein the operator controls the movement of the shaft 32 by grasping the externally located handle 34. The handle 34 remains external to the patient 12 to allow the surgeon or other operator to manipulate the tunneling shaft 32 along a desired path within the substernal space of the patient 12. The distal end 38 of the shaft 32 can be advanced upwardly, for example, to Fig.18BThe surgeon or other operator can view the path of the distal end 38 of the tunneling shaft 32 during the procedure by using the optical window 44 of an endoscope or other viewing device inserted into the inner lumen 46 of the shaft 32. The surgeon or other operator can use the distal end 38 of the tunneling shaft to tunnel through the tissue of the patient 12 by blunt dissection with the cutting tool 50 in the recessed position.

[0050] exist Fig.18B In the illustrated position, the operator can use, for example, the optical window 44 to determine that tissue (e.g., septal appendages, pericardium, scar tissue, or connective tissue) is directly adjacent to the distal end 38 of the shaft 32. In the illustrated position, the operator can deploy the cutting tool 50 to the deployed position (e.g., as shown in FIG. Fig.18C The cutting tool 50 is then moved to the extended position, such as shown in the figure, to cut tissue near the distal end 38 of the shaft 32, for example by using the sharp cutting of the leading edge 51 of the cutting tool 50. The operator can expand the cutting tool 50 to the expanded position by pressing the trigger 56. In some examples, during the pressing of the trigger 56, the operator can fix the handle and therefore the shaft 32 in the general position while advancing the cutting tool 51 beyond the distal end 38 to the expanded position to cut nearby tissue. Once the tissue has been cut by expanding the cutting tool 50, the cutting tool 50 can be retracted back to the recessed position (e.g., automatically or by releasing the trigger 56), and then advanced by the operator through the cut tissue to the extended position. Fig.18D The positioning is shown, for example, to provide a pathway for placement of a lead 16 in the anterior mediastinum.

[0051] like Figures 18A-18DAs shown, the operator can tunnel the distal portion of the shaft 32 or otherwise advance the distal portion from the incision site to the desired position so that the cutting tool 50 is selectively deployed from the recessed position to the deployed position, for example, cutting through tissue near the distal end 38, such as diaphragmatic appendages, pericardium, scar tissue or connective tissue as needed during the tunneling procedure. Depending on the patient's anatomical structure, tissue may be present along the path of the shaft 32 in the anterior mediastinum or other anatomical locations. During the initial insertion, the shaft 32 may penetrate the diaphragmatic appendages that were not cut with the initial incision. If the patient has not previously undergone a sternotomy or other surgery, the mediastinal tissue (pericardium, lungs) may move freely. After the incision is made and air is introduced, there may be an open gap, but the expansion of the lungs during breathing may fill this gap. The tool 30 may be particularly useful for patients who have previously undergone a sternotomy or other thoracotomy. These patients may therefore have severe adhesions to the posterior sternum. In such cases, the tissue may be a mixture of pericardium, scar tissue, or connective tissue that is formed in response to the injury caused by the first surgical procedure. When the distal portion of shaft 32 is introduced into these patients, shaft 32 may tunnel and cut (e.g., by selectively deploying cutting tool 50) through this mixture of tissue to safely place a lead, such as lead 16, within patient 12 as desired using the example techniques described herein.

[0052] like Figures 18A-18D As shown, the curvature of the tunneling shaft 18 is such that the distal portion of the tunneling shaft is biased toward the inner surface of the sternum 13. In addition, the front edge 51 (e.g., Figure 5B ) extends along a plane that is not orthogonal (e.g., substantially parallel) to the plane of the sternum 13 and the outer surface of the pericardial sac near the tunneling axis 32. For example, with the front edge 51 of the cutting tool 50 extending from Figure 3 This configuration may allow the blade arm 54 to be more easily driven from a mechanism within the handle 34, compared to the 90 degree rotated configuration shown in FIG.

[0053] When employed by the tunneling tool 30, the cutting tool 50 may have any suitable orientation. Figure 3-6 In the example of , the plane of the leading edge / sharp edge 51 of the cutting tool 50 is oriented to be generally parallel to the central longitudinal axis of the handle 34 and the direction in which the trigger 56 is pressed to deploy the cutting tool 50. In addition, the cutting tool 50 extends along a plane such that during normal use to tunnel through tissue in the substernal space 3 as described herein, the cutting tool 50 is oriented to be non-orthogonal (e.g., generally parallel) to the inner surface of the sternum, pericardium, and / or heart of the patient 12.

[0054] In addition to or as an alternative to the cutting tool 50, the tool 30 can include an electrosurgical implement. In this example, the drive arm 54 can be configured to conduct current and be insulated from tissue contact within the tunneling shaft 32 when in a recessed position. An electrical connector can be located in the handle 34, for example. In this example, pressing the trigger 56 can temporarily advance the electrosurgical tool beyond the distal end 38 to cauterize or dissect tissue.

[0055] Figures 7A-7C is a schematic diagram showing a distal portion of another example tunneling tool 70 according to examples of the present disclosure. Fig. 7A and 7B Shown along Figure 7C A cross-sectional view of the tunneling tool 70 taken at cross section CC. Figure 7C Shown along Fig. 7A A cross-sectional view of the tunneling tool 70 taken at cross section BB. The tunneling tool 70 may be Figure 3-6 The tunneling tool 30 described is substantially the same, and similar features are similarly numbered. However, unlike the tunneling tool 30, the tool 70 includes a single blade arm 54 that translates to transfer mechanical energy from the handle 34 to the cutting tool 50, rather than two blade arms 54A, 54B as shown for the tunneling tool 30. The single blade arm 54 can extend from the handle 34 along the curved tunneling axis to the cutting tool 50 positioned at the distal end 38 of the tunneling tool 70. As previously described, the blade arm 54 can translate (e.g., by pressing the trigger 56) to move the cutting tool 50 from a recessed position (e.g., Fig. 7A ) to the expanded position (as shown) Figure 7B As shown, a single drive arm 54 transmits mechanical energy from the handle 34 to the proximal side of the cutting tool 50, while the other side of the cutting tool 50 is anchored (e.g., by a pin) to a portion of the tunneling shaft 32, such as the optical window 44. The transmitted energy causes the cutting tool 50 to rotate about the anchor point to expose the sharp leading edge of the cutting tool 50 to the tissue near the optical window 44. In some examples, the use of a single blade arm 54 rather than two or more blade arms, such as blade arms 54A and 54B of the tunneling tool 30, allows the diameter of the tunneling shaft 32 to be reduced.

[0056] Fig. 8A and 8B is a schematic diagram showing a distal portion of another example tunneling tool 80 according to another example of the present disclosure. Fig. 8A It is from Fig. 7A and 7B The cross-sectional view of the cutting tool 70 is shown in the example from a perspective similar to that shown in FIG. Figure 8B is a side view of the distal portion of the tunneling tool 80. The tunneling tool 70 may be used with respect to Figure 3-6The tunneling tool 30 described is substantially the same, and similar features are numbered similarly. However, in contrast to the tunneling shaft 32 comprising a single curved tube within the inner lumen, the tunneling tool 80 comprises a tunneling shaft 32 comprising a first curved tube 82 and a second curved tube 84 of substantially matching curvature. The diameter of the first tube 82 is greater than the diameter of the second tube 84, so that the second tube 84 is, for example, coaxially nested within the first tube 82. The first tube 82 and the second tube 84 can be sized and configured to be movable relative to each other. In some examples, the second tube 84 can be substantially rigid and made of, for example, a metal or metal alloy, while the first tube 82 can be configured to be flexible, for example, using a flexible plastic material.

[0057] In some examples, movement of the first tube 82 relative to the second tube 84 can be actuated by depressing the trigger 56 to selectively transition the cutting tool 50 between the recessed configuration and the deployed configuration, for example, as described above with respect to Figure 3-6 However, instead of using the blade drive arm 54 to transmit force from the handle 34 to convert the cutting tool 50 from the recessed position to the expanded position, in Fig. 8A and 8B In the example of FIG. 5 , actuation of the trigger 56 can cause the first tube 82 to move distally while the second tube 84 remains stationary. The optical window 44 can be connected to the fixed second tube 84. Fig. 8A As shown, the cutting tool 50 can be welded or otherwise connected to the metal base 86 at a location 81 at the distal end of the first tube 82 so that distal movement of the first tube 82 brakes the cutting tool 50 to extend from the concave configuration out of the hole in the optical window 44 (such as Figure 8B 44) to reach the expanded configuration, for example to dissect tissue immediately adjacent to the optical window 44. In other examples, the second tube 84 can be moved with actuation of the trigger 56, while the first tube 82 is fixed, wherein the cutting tool 50 is connected to the second tube 84, and the optical window 44 is connected to the first tube 82. In such examples, movement of the second tube 84 can use the trigger 56 to convert the cutting tool 50 from the recessed configuration to the expanded configuration.

[0058] In some examples, the tunneling tool 80 can include a lubricating layer positioned between the outer surface of the second tube 84 and the inner surface of the first tube 82 to facilitate movement of the tubes 82 and 84 relative to each other. For example, the outer surface of the second curved tube 84 is hard-coated with a lubricating layer 81, for example, in the form of baked Teflon or other lubricants. Additionally or alternatively, the lubricating layer 81 can be formed on the inner portion of the first curved tube 82.

[0059] In some instances, both the first tube 82 and the second tube 84 can be flexible. In such instances, one or both of the first tube 82 and the second tube 84 (e.g., only the second tube 84) can include one or more flexible wires (not shown) that can be extended along the longitudinal length to allow the tunneling shaft to maintain a certain curvature when being bent by the user. For example, one or more flexible wires can be embedded in the wall of the first tube 82 and / or the second tube 84, or are additionally connected to the first tube 82 and / or the second tube 84 (e.g., using a heat-shrinkable outer sheath). In this way, the curvature or other shapes of the shaft 32 can be modified by the operator as needed to optimize the geometry of the shaft 32 for the anatomical structure of a specific patient. In some instances, the first tube 82 and / or the second tube 84 can be extruded in, for example, the side wall of the tube using this flexible wire. In some instances, one or more flexible wires can be 21 gauge (about 0.0318 inch diameter) 301 stainless steel, 1 / 4 hard wire, but other instances are contemplated.

[0060] Similar to the tunneling tool 30, the tunneling tool 80 includes an optical window 44 through which an endoscope or other optical device can be used to allow a surgeon or other user to view the gap outside the distal end 38 of the tool 80 during the implantation procedure. Likewise, as described above, the tunneling tool 80 includes a semicircular cutting tool 50 (e.g., a semicircular blade) that can be selectively actuated between a recessed position and an expanded position, such as to allow the tunneling tool 80 to be used for blunt dissection and sharp dissection of tissue, respectively, as needed during implantation in the substernal space 3 based on the tissue that can be viewed through the optical window 44. In some examples, the semicircular blade 50 is welded or otherwise attached in a vertical arrangement relative to the circular metal base 86.

[0061] Fig.9A and 9B is a schematic diagram illustrating a distal portion of another example tunneling tool 90 from side and top cross-sectional views according to another example of the present disclosure. Fig. 9B yes Fig.9A 90. The tunneling tool 90 may be used in conjunction with Figure 3-6 The tunneling tool 30 described is substantially identical and like features are similarly numbered.

[0062] exist Fig.9A and 9B In the example of FIG. 1 , the tunneling shaft 32 has a substantially elliptical (e.g., elongated elliptical) cross-section in a plane orthogonal to the longitudinal axis of the tool 90. The elliptical cross-sectional shape allows for a substantially flat surface (at the center of the tunneling shaft 32) to be substantially flat when utilized in accordance with the tunneling techniques described herein. Fig.9AThe "top" and "bottom" surfaces are shown in the direction shown in FIG. 1 ) and are located near the inner surface of the sternum and the outer surface of the pericardial sac (with Figure 3-6 9). In some examples, the "flat upper" surface of the shaft 32 can be guided or otherwise contacted with the inner surface of the sternum during the tunneling procedure, which can provide increased stability of the tool 90 in one or more hands of the surgeon or other operator. The tunneling shaft 32 includes an inner lumen 46, blade arms 54, and one or more additional lumens 92 (only a single lumen is numbered in FIG. 9) extending from the proximal end 36 of the tunneling shaft 32 to the distal end 38.

[0063] In some instances, the tunneling shaft 32 can be an extruded tube that includes a desired number of inner lumens having a desired size, such as a diameter. The one or more inner lumens of the tunneling shaft 32 are used to insert one or more scopes (e.g., flexible endoscopes) for viewing lead insertion / placement outside of the optical window 44 (e.g., in lieu of using an introducer sheath), one or more blade drive arms 54, one or more flexible guide wires for positioning and defining the curvature of the tunneling shaft 32, reinforcing rods, working channels for additional instruments (for contrast dye, tools for electrocautery), etc. Similar to other examples described herein, the tunneling shaft 32 includes an optical window 44 and a cutting blade 50, the optical window being located at the distal end 38 for allowing the surgeon to view the gap near the distal end 38 during the tunneling procedure, and the cutting blade can be selectively deployed during the tunneling procedure and retracted as needed to cut tissue. Fig.9A and 9B In the example of FIG. 5 , the leading edge of the cutting tool 50 extends in a straight line with the major axis of the elliptical cross-section of the tunneling shaft 32 .

[0064] Figures 10A-10C is a schematic diagram showing a side view ( Fig. 10A and 10B ) and top cross-sectional view ( Fig. 10C )Look at the distal portion of another example tunneling tool 100. Fig. 10C yes Fig. 10A 1. The tunneling tool 100 may be used in conjunction with a cross section EE of the tool 100. Figure 3-6 The tunneling tool 30 described is substantially identical and like features are similarly numbered.

[0065] and Fig.9A and 9B Similar to tool 90, tool 100 includes a tunneling shaft 32 having a substantially elliptical cross-sectional shape. The elliptical cross-sectional shape allows a substantially flat surface (at the bottom) of tunneling shaft 32 to be formed when utilized in accordance with the tunneling techniques described herein. Fig. 10AThe top and bottom surfaces shown in FIG. 1 are located near the inner surface of the sternum and the outer surface of the pericardial sac (with Figure 3-6 The tool 30 shown in FIG. 1 has a circular top surface and a bottom surface that are opposite). Fig. 10A and 10C As shown, the leading edge of the cutting tool 50 can extend in a direction substantially perpendicular to the long axis of the elliptical cross-section of the tunneling axis 32 and be positioned between the additional (or “working”) lumens 92 . Fig. 10B Examples are shown in which the leading edge of the cutting tool 50 can extend in a non-perpendicular direction that is angled relative to the long axis of the elliptical cross-section of the tunneling axis 32. The angled orientation of the cutting tool 50 allows the length of the cutting tool 50 to be longer than, for example, the length of the cutting tool 50 that is oriented perpendicular to the long axis of the elliptical cross-section, thereby producing a larger cutting profile.

[0066] Figures 11A-11C 1 is a schematic diagram showing another example tunneling tool 110 according to an example of the present disclosure. The tunneling tool 110 can be used with respect to Figure 3-6 The tunneling tool 30 described is substantially identical and like features are similarly numbered. Fig. 11B The distal end 38 of the tunneling shaft 32 is shown, containing an optical window 44 and a cutting tool 50 (shown in a recessed position). Fig. 11C Shown with Fig.11A 34 is similar to the tunneling tool of the present invention, but the outer portion of the handle 34 is removed for display of the tunneling tool 110, wherein the mechanism is used to allow the trigger to be actuated so that mechanical energy is translated to the cutting tool 50, for example, to selectively unfold the cutting tool 50 for sharp dissection of tissue. Unlike the tunneling tool 30, the tool 110 includes a guide member 88 extending from the handle 34 to the vicinity of the tunneling axis 32 and coplanar with the tunneling axis. The tunneling axis 32 is bent toward the guide member 88. The handle 34 has a shape configured to accommodate the fingers of the surgeon's or other operator's hand, but can have any other suitable configuration for grasping. When grasped by the surgeon or other operator, fingers such as the index finger can be positioned in a manner that allows the finger to easily press and release the trigger 56.

[0067] During a procedure for obtaining substernal access into a patient and creating a substernal tunnel, once the distal end 38 is inserted into the patient 12, the guide member 88 can assist the surgeon or other operator in advancing the tunneling shaft 32. In some instances, the curved distal portion 90 of the guide member 88 can be configured to "ride" on the skin above the sternum 13 during this procedure, rather than being bonded to the skin. In this way, the guide member 88 can limit the depth to which the tunneling shaft 32 below the sternum 13 can be advanced during the tunneling procedure. Further, the curvature of the tunneling shaft 32 toward the guide member 88 can cause the distal end 38 to "ride" near the medial surface of the sternum 13 during its upward advancement as an additional aid to the operator. In some instances, the distance 93 between the guide member 88 and the tunneling shaft 32 can be adjusted by the surgeon or other operator as desired, for example based on the patient's physical characteristics. Examples of guide members 88 employed in tunneling tools may include guide members described by Malewicz et al. in US Patent Application No. 15 / 204,579, the entire contents of which are incorporated herein by reference.

[0068] like Fig. 11C As shown, the handle 34 includes an elastic member, such as a cable, chain or belt 95, connected to the trigger 56. When the trigger is pulled, the elastic member drives the slider 57, which in turn activates the hammer mechanism, which temporarily deploys the cutting tool 50 to cut the adhesion. The cutting tool 50 automatically retracts as in the mechanism described above.

[0069] Fig.12 1 is a schematic diagram showing another example tunneling tool 120 according to an example of the present disclosure. The tunneling tool 120 can be used with respect to Fig.11A The tunneling tool 110 described in Figures 1-1E is substantially the same, and similar features are similarly numbered. An endoscope or other tool can be inserted into the proximal opening 48 of the handle 34 and advanced, for example, through the inner lumen 46 to reach at or near the distal end 38 of the tunneling shaft 32. The shape of the handle 34 of the tool 120 is different from the shape of the handle 34 of the tool 110. For example, the handle 34 is shaped so that when grasped by the hand of a surgeon or other operator, the trigger 56 can be pressed or otherwise actuated by the thumb of the hand rather than a finger such as an index finger as in the case of the tool 110.

[0070] Fig.13A and 13B 1 is a schematic diagram showing another example tunneling tool 130 according to an example of the present disclosure. The tunneling tool 130 may be used in conjunction with Fig.12 The tunneling tool 120 described is substantially identical, and like features are similarly numbered. Fig. 13B The proximal opening 48 in the handle 34 is shown, and Fig.13AAn endoscope or another tool 94 is shown inserted proximally of the opening 48. As previously described, the endoscope or other tool 94 can be inserted through the opening 48 in the handle 34 into the inner lumen 46 of the tunneling shaft 32 to, for example, allow a surgeon or other operator to view through the optical window 44 located at the proximal end 38 of the shaft 32 during tunneling. Fig.13A and 13B As shown, the trigger 56 may be shielded by an adjacent wall of the handle 34 by recessing the trigger 56 somewhat into the surface of the handle to, for example, prevent unintended depression of the trigger 56 during a tunneling procedure.

[0071] Fig.14 1 is a schematic diagram showing another example tunneling tool 140 according to an example of the present disclosure. The tunneling tool 140 can be used with respect to Fig.11A -11E are substantially identical to the tunneling tool 110 described above, and similar features are similarly numbered. Unlike the tunneling tool 110, the handle 34 of the tunneling tool 140 includes a trigger guard 96 for preventing the surgeon or other operator from accidentally depressing the trigger 56 during the tunneling procedure.

[0072] Figures 15A-15C 1 is a schematic diagram showing another example tunneling tool according to an example of the present disclosure. Fig.11A The tunneling tool 110 described in connection with FIG. 11E is substantially identical, and similar features are similarly numbered. Unlike the tunneling tool 110 , the vertical portion of the handle 34 of the tunneling tool 140 is angled further toward the distal end 38 of the tunneling shaft 38 .

[0073] Figures 16A-16E is a schematic diagram showing another example tunneling tool 160 according to examples of the present disclosure. Fig.16A and 16B Two different perspective views of tool 160 are shown. Fig. 16C and 16D The distal end 38 of the tunneling shaft 32 is shown with the optical window 44 and the cutting tool 50 in a recessed position and an expanded position, respectively. Fig.16E A cross-sectional view of the handle 34 is shown.

[0074] Although the tunneling shaft 32 of the tool 120 is substantially straight from the proximal end 26 to the distal end 38, in some instances, the tunneling shaft 32 may be curved, e.g., Figure 3-630 is similar to the tunneling shaft 32 of the tool 30 shown in FIG. The tunneling shaft 32 includes an inner lumen 46 that is open and can receive a rigid or flexible scope through a proximal opening 48 in the handle 34. The distal end 38 of the tunneling shaft 32 can be made of a clear or otherwise transparent material to enable direct viewing of the tissue through which the shaft 32 is advanced. The handle 34 houses the mechanism and includes a trigger 56 that can cause the cutting tool 50 to move from a recessed position ( Fig. 16C ) extends to the expanded position ( Fig.16D ). When the cutting tool 50 is in the concave position, the distal end 38 is typically blunt, for example, to prevent damage to vital organs such as the mammary arteries or the lungs during the tunneling procedure. Fig. 16C and 16D The distal end 38 having an optical window 44 in the form of an angled tip is shown. However, other distal end geometries are contemplated. For example, Fig.17 Another example is shown in which the distal end 38 includes a dome or spherical shaped tip that may be made of a clear or otherwise transparent material.

[0075] like Fig. 16C As shown, the cutting tool 50 is recessed in the channel 98 at the distal end 38 when in the recessed position. The tunneling shaft 32 also contains additional lumens 102A and 102B, which can be used, for example, for insufflation, focusing, adding contrast, flushing the lens, removing cavitation, etc.

[0076] Reference Fig.16E , the proximal end 104 of the cutting tool (which may be similar to the proximal end of one or more blade arms 54) is engaged to a spring-loaded slider 106. The inclined surface 108 of the slider 106 acts as a cam. The rod 112 pivots around the first column 114, and its travel is limited by the second column 116 that travels inside the groove of the handle 34. The tip 118 of the rod 112 engages the slider ramp 108 to drive the cutting tool 50 forward to the deployed position by pressing the rod 112 of the trigger 56 when necessary. In this example, the cutting tool 50 can remain in the deployed position until the trigger 56 is no longer pressed, which is contrary to automatically retracting to the recessed position when the trigger 56 is pressed, for example.

[0077] Various examples have been described. These and other examples are within the scope of the following claims and examples.

[0078] Example 15. A method comprising: inserting a distal portion of a tool into the patient's body through an incision in the patient's body, wherein the tool comprises: a handle; and a tunneling shaft connected to the handle, wherein the tunneling shaft extends from a proximal end to a distal end, and at least a portion of the tunneling shaft extends in a curved direction between a first end and the distal end, wherein the distal end of the tunneling shaft comprises a cutting tool with a sharp edge, the cutting tool being movable from a recessed position to an expanded position, in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft, in which the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft; and when the distal portion of the tool is inserted into the patient's body through the incision, expanding the cutting tool from the recessed position to the expanded position to cut the patient's tissue using the sharp edge of the cutting tool.

[0079] Example 16. The method of Example 15, wherein the incision is proximal to the patient's xiphoid process, the method further comprising, after cutting the tissue, advancing the distal portion of the tool, the patient's anterior mediastinum, to create a substernal tunnel between the patient's sternum and the patient's heart.

[0080] Example 17. A method according to any one of Examples 15 or 16, wherein the tunneling shaft of the tool is positioned within the lumen of an introducer sheath when inserted into the patient's body through the incision, the method further comprising: after insertion into the patient's body, withdrawing the tunneling shaft from the lumen of the introducer sheath to leave the distal portion of the introducer sheath in the patient's body; inserting a medical lead into the lumen of the introducer sheath while in the patient's body; and subsequently, removing the introducer sheath while in the patient's body to leave the medical lead in the patient's body.

[0081] Example 18. A method of any of Examples 15 to 17, wherein the handle includes a trigger connected to the cutting tool, wherein deploying the cutting tool from the recessed position to the deployed position includes pressing the trigger to transfer mechanical energy to the cutting tool to move the cutting tool from the recessed position to the deployed position.

[0082] Example 19. The method of Example 18, wherein the tool includes at least one blade arm extending from the cutting tool to the handle, wherein pressing the trigger to transfer the mechanical energy to the cutting tool to move the cutting tool from the recessed position to the expanded position includes transferring the mechanical energy from the handle to the cutting tool through the at least one blade arm.

[0083] Example 20. The method of Example 19, wherein the at least one blade arm comprises a single blade arm coupled to a first end of the cutting tool and an opposite end of the cutting tool is anchored to the tunneling shaft.

[0084] Example 21. The method of any one of Examples 18 to 20, wherein pressing the trigger to transfer mechanical energy to the cutting tool to move the cutting tool from the recessed position to the deployed position includes automatically moving the cutting tool from the deployed position back to the recessed position.

[0085] Example 22. The method of any of Examples 15 to 21, wherein deploying the cutting tool from the recessed position to the deployed position comprises extending the sharp edge by approximately 0.25 millimeters (mm) to approximately 2 mm beyond the distal end of the tunneling shaft when in the deployed position.

[0086] Example 23. A method of any of Examples 15 to 22, wherein the tunneling shaft comprises a first shaft and a second shaft, the second shaft being nested within the first shaft, wherein deploying the cutting tool from the recessed position to the deployed position comprises moving the first shaft and the second shaft relative to each other around a longitudinal axis of the tunneling shaft.

[0087] Example 24. The method of Example 23, wherein the distal end of the tunneling shaft includes an optical window, and wherein one of the first shaft and the second shaft is connected to the cutting tool, and the other of the first shaft and the second shaft is connected to the optical window.

[0088] Example 25. The method of any one of Examples 15-24, wherein the tunneling shaft comprises an inner lumen extending from the proximal end to the optical window.

[0089] Example 26. The method of any one of Examples 15 to 25, wherein the tunneling shaft comprises an inner lumen extending from the proximal end to the distal end of the tunneling shaft and an optical window located at the distal end of the tunneling shaft.

[0090] Example 27. The method of any of Examples 15 to 26, further comprising advancing the distal end of the tunneling shaft while the cutting tool is in the concave position to bluntly dissect another tissue of the patient.

[0091] Example 28. The method of any of Examples 15 to 27, wherein the tool includes a guide member extending from a distal end of the guide member to a proximal end of the guide member, wherein the proximal end of the guide member is connected to the handle, and wherein the tunneling axis extends along the guide member and is coplanar with the guide member.

[0092] Example 29. The method of any of Examples 15 to 28, wherein the length of the tunneling shaft from the proximal end to the distal end is about 4 inches to about 12 inches.

[0093] Example 30. The method of any of Examples 15 to 29, wherein the tunneling shaft exhibits a radius of curvature of about 15 inches to about 40 inches over at least a portion of the length of the tunneling shaft.

[0094] Example 31. A method according to any one of Examples 15 to 30, wherein when the distal portion of the tool is inserted into the patient's body through the incision, the cutting tool is expanded from the concave position to the expanded position to utilize the sharp edge of the cutting tool to cut the patient's tissue, including when the distal portion of the tool is inserted into the patient's body through the incision, the cutting tool is expanded from the concave position to the expanded position to utilize the sharp edge of the cutting tool to cut at least one of the patient's septal appendages, pericardium, scar tissue or connective tissue.

Claims

1. A tool comprising: handle; as well as a tunneling shaft coupled to the handle, wherein the tunneling shaft extends from a proximal end to a distal end and at least a portion of the tunneling shaft extends in a curved orientation between the proximal and distal ends, wherein the distal end of the tunneling shaft includes a cutting tool having a sharp edge, the cutting tool being movable from a recessed position in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft to an expanded position in which the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft, wherein the handle includes a trigger coupled to the cutting tool, wherein pressing the trigger in a first direction transfers mechanical energy to the cutting tool to move the cutting tool from the recessed position to the deployed position in a second direction, wherein the first direction is different from the second direction, wherein the tool further comprises at least one blade arm extending from the cutting tool to the handle, wherein the at least one blade arm is configured to transfer the mechanical energy from the handle to the cutting tool when the trigger is depressed, and Wherein the trigger and the cutting tool are configured such that pressing the trigger causes the cutting tool to move from the recessed position to the deployed position and automatically moves the cutting tool back to the recessed position without releasing the trigger.

2. The tool of claim 1, wherein the at least one blade arm comprises a single blade arm coupled to one end of the cutting tool and an opposite end of the cutting tool is anchored to the tunneling shaft.

3. The tool of any one of claims 1 to 2, wherein the sharp edge of the cutting tool extends 0.25 millimeters (mm) to 2 mm beyond the distal end of the tunneling shaft when in the deployed position.

4. The tool according to any one of claims 1 to 3, wherein the tunneling shaft comprises a first shaft and a second shaft, the second shaft being nested within the first shaft, and wherein the first shaft and the second shaft are movable relative to each other about a longitudinal axis of the tunneling shaft.

5. The tool of claim 4, wherein the distal end of the tunneling shaft comprises an optical window, and wherein one of the first shaft and the second shaft is coupled to the cutting tool, and the other of the first shaft and the second shaft is coupled to the optical window.

6. The tool according to any one of claims 1 to 5, wherein the tunneling shaft comprises an inner lumen and an optical window, the inner lumen extending from the proximal end to the distal end of the tunneling shaft, and the optical window is located at the distal end of the tunneling shaft.

7. The tool of any one of claims 1 to 6, wherein the tunneling shaft comprises an extruded tube defining a plurality of inner lumens extending from the proximal end to the distal end.

8. A tool according to any one of claims 1 to 7, wherein the distal end of the tunneling shaft is configured to perform blunt dissection of the patient's tissue when the cutting tool is in the recessed position, and is configured to perform sharp dissection of the tissue when the cutting tool is in the expanded position.

9. The tool according to any one of claims 1 to 8, further comprising a guide member extending from a distal end of the guide member to a proximal end of the guide member, wherein the proximal end of the guide member is connected to the handle, and wherein the tunneling axis extends along the guide member and in the same plane as the guide member.

10. The tool of any one of claims 1 to 9, wherein the length of the tunneling shaft from the proximal end to the distal end is 4 inches to 12 inches.

11. The tool of any one of claims 1 to 10, wherein the tunneling shaft exhibits a radius of curvature of 15 inches to 40 inches over at least a portion of the length of the tunneling shaft.

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