Medical tools for and methods of gaining access to extra vascular spaces

In some examples, a tool for, e.g., creating a sub-sternal tunnel in a patient or other use, is described. The tool may include a handle and a tunneling shaft 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 orientation between the first end to the distal end. The distal end of the tunneling shaft includes a cutting tool having a sharp edge. The cutting tool is moveable from a recessed position in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft to a deployed position in which the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft in the deployed position, e.g., to cut pericardium, scar tissue, and/or connective tissue with the sharp edge.

TECHNICAL FIELD

The present disclosure pertains to tools and associated methods for safely gaining access to spaces within patient, and more particularly to those suited to safely gain access into a sub-sternal or other extravascular space for the positioning of a medical device therein.

BACKGROUND

Some medical procedures may include crossing multiple tissue layers to gain access to a location within the body of a patient. Such medical procedures may include implanting one or more medical devices or components thereof, e.g., medical electrical leads, at the location. One manner of accessing an intrathoracic location is substernally and includes traversing one or more layers of tissue, e.g., diaphragmatic attachments that attach the diaphragm to the sternum. An example of a procedure is the implantation of the distal portions of one or more leads sub sternally, and may include using an implant tool to access the intrathoracic cavity of the patient. The 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 ICDs may include, or may be part of a system that includes, a subcutaneously-implantable housing that encloses a pulse generator or other electronics of an ICD. The housing of some ICDs may be connected to the one or more leads, which may be configured to deliver defibrillation and/or pacing pulses.

SUMMARY

This disclosure provides tools and implant techniques utilizing such tools to gain access and implant medical devices or components thereof within spaces within a patient, e.g., a lead within an extravascular space. In one example, this disclosure provides a tool for creating a sub-sternal tunnel in a patient. The tool comprises 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 the first end to the distal end, wherein the distal end of the tunneling shaft includes a cutting tool having a sharp edge, the cutting tool moveable from a recessed position in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft to a deployed position in which the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft in the deployed position.

In another example, this disclosure is directed to a method, e.g., for creating tunnel in a patient with a tool. The method inserting a distal portion of a tool in a patient through an incision in the patient, wherein the tool comprises 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 the first end to the distal end, wherein the distal end of the tunneling shaft includes a cutting tool having a sharp edge, the cutting tool moveable from a recessed position in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft to a deployed position in which the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft in the deployed position; and deploying the cutting tool from the recessed position to the deployed position, while the distal portion of the tool is inserted in the patient through the incision, to cut a tissue of the patient with the sharp edge of the cutting tool.

This summary 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 within the accompanying drawings and description below. Further details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the statements provided below.

The details of one or more examples of this disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of this disclosure will be apparent from the description and drawings, and from the claims.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is not intended to limit, in any way, the scope, applicability, or configuration of the tools and techniques described in this disclosure. Rather, the following description provides practical examples, and those skilled in the art will recognize that some of the examples may have suitable alternatives.

FIGS. 1A-Bare schematics showing an exemplary extravascular implant of an exemplary system10that includes a pulse generator14and an implantable medical electrical lead16coupled thereto. Pulse generator14is shown implanted subcutaneously on the left mid-axillary of a patient12, superficially of the patient's ribcage. Pulse generator14, which may be configured to provide cardiac pacing and/or defibrillation therapy, includes a hermetically sealed housing in which the appropriate electronics and a power supply are contained, and which is formed from a conductive material, such as titanium, or from a combination of conductive and non-conductive materials. Pulse generator14further includes a connector module by which lead16is electrically coupled to the electronics contained therein, for example, by electrical contacts contained within the connector module and a corresponding hermetically sealed feedthrough assembly, such as is known in the art. The conductive material of device housing may be employed as an electrode, for example, to provide the aforementioned therapy in conjunction with one or more pace/sense electrodes22,26and/or defibrillation electrodes24,28of lead16, which is shown implanted in a sub-sternal space3, for example, within the loose connective tissue and/or sub-sternal musculature of the anterior mediastinum.

Lead16may have any of a number of configurations. For example, lead16may include more or fewer pace/sense electrodes. In another example, lead16may include more or less than two defibrillation electrodes24,28and/or have a defibrillation electrode(s) that is formed of 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.), each of which is incorporated herein by reference in its entirety.

With reference toFIG. 1B, the sub-sternal space3may be viewed as being bounded laterally by pleurae39that enclose the patient's lungs, posteriorly by the pericardial sac15that encloses the patient's heart6, and anteriorly by the sternum13. In some instances, the anterior wall of the anterior mediastinum may also be formed by the transversus thoracis and one or more costal cartilages. AlthoughFIGS. 1A and 1Bare described in the context of the distal portion of lead16being placed within the sub-sternal space3, in other examples, the tools and implant techniques described herein may be used to implant a distal portion of the lead16at other locations outside the heart. In one example, the tools may be used to place the distal portion of lead16intra-pericardially via a percutaneous subxiphoid approach. In some examples, the tools and implant techniques described herein could be used for implanting other medical devices or components thereof and/or for other spaces within the patient, such as, implanting a leadless pacemaker on or near outside of heart via substernal access.

FIG. 2is a schematic showing an access site A for making a passageway between a patient's diaphragm19and xiphoid process20of sternum13, for example, to create a sub-sternal tunnel in which to position a medical device, such as medical electrical lead16. After making a superficial incision, an operator, using a suitable tunneling tool, may open a passageway between diaphragmatic attachments18and diaphragm19, for example, by blunt and/or sharp dissection, in which the operator may employ a tunneling tool, such as those example tools described herein, to both create the passageway and then form a sub-sternal tunnel (e.g. along the dotted line ofFIG. 2). Because the bony structure of the sternum inhibits external palpation, the operator must take extra care, during the dissection (e.g., blunt and/or sharp) and/or tunneling, not to injure sub-sternal structures or the chest cavity, which could compromise the pleura of the lungs or the heart6. Tools and associated methods disclosed herein are configured to help an operator gain the desired sub-sternal access and create a space in which to position a medical device, such as medical electrical lead16, in a controlled fashion that mitigates the risk of injuring bodily organs.

In some examples, a distal portion of lead16may be implanted to be located between the posterior sternum13and the anterior wall of the heart6. The implant procedure may be performed by using a blunt trocar with a flexible port to create a small tunnel near the posterior aspect of the sternum13via entry into the body near the xiphoid process20. The distal portion of lead16, e.g., the portion of lead16carrying some or all of electrodes22,24,26,28, is then placed in the anterior mediastinum. The proximal end of lead16is then tunneled subcutaneously or submuscularly to a left midxillary location under and connected to the pulse generator14. Pulse generator14and lead16are able to provide, e.g., defibrillation, anti-tachycardia pacing (ATP), bradycardia pacing, post-shock pacing, and asystole “lifeboat pacing.”

Suitable tunneling tools with blunt trocars may be utilized to implant lead16in patient12. However, patients that have had previous median sternotomies tend to have extensive scar tissue and the pericardium is often adhered to the posterior of the sternum. This scar tissue makes it very challenging and, in some cases, relatively undesirable for a blunt trocar to create a small tunnel in the anterior mediastinum. A surgeon may not want to enter the substernal space of such patients unless they have direct visualization of the location. Thus, patients that have had one or more previous median sternotomies may be less likely to receive an extravascular ICD or other medical device that includes the implantation of distal portion of lead16between the posterior sternum13and the anterior wall of the heart6in the manner described above.

In accordance with some examples of the disclosure, a tunneling tool (or trocar) is described that allows for a forward, hemispherical view and selective dissection (e.g., selective between blunt and sharp dissection) of tissue while tunneling through diaphragmatic attachments, pericardial adhesion, and other soft tissue. Examples include tunneling tools having a knife blade or other cutting tool with a sharp edge, e.g., on the distal end of the tool, for accessing the substernal space, dissection adhesions, and creating working room, e.g., in the thoracic cavity. Such tunneling tools may also include an optical window for a surgeon or other user to visualize, e.g., using an endoscope inserted within the tunneling tool, the movement of a distal end of the tunneling tool through tissue. Such visualization may provide for better guidance of the tunneling tool during an implant procedure and allow for a clinician to identify locations in which it may be desirable to deploy the cutting tool, e.g., to cut tissue adjacent the distal end of the tunneling tool using sharp dissection rather than blunt dissection.

Examples of the disclosure may provide tools that allow for blunt dissection/tunneling as well as transection of adhesions under direct visualization. Such a tool enables safe placing of extravascular ICDs even in patients with previous sternotomies. The optical window with integrated knife or other cutting blade may allow for easy identification of tissue prior to dissection during a tunneling procedure. Example of the disclosure may also allow for easier access into the thorax of a patient with previous sternotomies for a coronary artery bypass graft (CABG) or valve replacement. The example tool may allow for the reduction of pericardial adhesions to create working space for placement, adjustment, and removal of lead.

FIGS. 3-6are functional schematic diagrams illustrating an example tunneling tool30for gaining sub-sternal access and creating a sub-sternal tunnel in a patient, according to some examples.FIG. 3illustrates tunneling tool30including tunneling shaft32and handle34.FIG. 4illustrates a cross-section view of tunneling shaft32about cross-section A-A shown inFIG. 3.FIGS. 5A and 5Billustrate the distal end38of tunneling shaft32.FIG. 6illustrates a cross-sectional view of handle34.

As shown inFIG. 3, tunneling shaft32of tunneling tool30extends from proximal end36to distal end38(or “distal tip38”). Tool30also includes handle34, which is shown coupled to proximal end36of tunneling shaft32. Rather than extend from proximal end36to distal end38in a linear or straight manner, at least a portion of tunneling shaft32extends in a curved orientation from proximal end36to distal end38, e.g., relative to axis40. Axis40may be defined by a central longitudinal axis of handle34or may be defined by a portion of shaft32that extends initially from handle34in a substantially straight manner before exhibiting a curved orientation beginning at a point between proximal end36and distal end38of shaft32. The curved orientation of tunneling shaft32results in offset32A between distal end38and axis40shown inFIG. 3. Offset32A may range from approximately 0.35 inches to approximately 1.25 inches, such as, approximately 0.720 inches, although other examples are contemplated. In some instances, the curvature of tunneling shaft32may maintain the path of the distal tip close to posterior side of sternum and away from vital organs like lung or heart during a tunneling procedure.

In some examples, tunneling shaft32be curved about the entire length from proximal end36to distal end38(e.g., as shown inFIG. 3) or may include one or more sections that are substantially straight with one or more other sections that are curved. For example, a proximately portion of the tunneling shaft32extending directly from handle34may be approximately straight for some of the length of tunneling shaft32and then transition to a more distal portion of tunneling shaft32that is curved. In some examples, the curved portion of tunneling shaft exhibits a radius of curvature of about 15 inches to about 40 inches.

Tunneling shaft32may be tubular, e.g., have a circular or oval outer profile and/or define one or more inner lumens, as shown inFIGS. 4-6. Any suitable material may be used for tunneling shaft32, e.g., metals (stainless steel, coated steel, titanium alloys, aluminum alloys and others) and plastics (unfilled and filled with suitable fiber like glass or carbon for strength and rigidity) may be utilized. Suitable plastic materials include but are not limited to acetal copolymer, polytetrafluoroethylene (PTFE)(e.g., TEFLON), polyether ether ketone (PEEK), polyphenylsulfone (PPSU)(e.g., RADEL), and polycarbonate. In some examples, tunneling shaft32may be formed of a material that allows for all or at least a portion of tunneling shaft32to be transparent along the length of shaft32. Shaft32may be substantially rigid so the clinician can control accurately the position of the tip in relation to vital organs under visualization afforded by fluoroscopy or other techniques via optical window44. To that end, in some examples, the tip of shaft32preferably has at least some metal components (like a metal blade) which will allow visualization using suitable medical imaging technology.

In some examples, rigidity of shaft32may be described in the context of possible forces that may act of shaft32, e.g., during an implant procedure. As one example, there may be a force an operator may apply to keep shaft32(e.g., distal end38) pressed against sternum13of patient12. The rigidity of shaft32may be such that shaft32does not flex significantly when the operator is biasing shaft32upwards/anteriorly. In some examples, shaft32exhibits substantially no flex when greater than about 5 pounds of force is applied to distal end38in direction37shown inFIG. 3. In some examples, shaft32does not “jam up” (e.g. can still deploy cutting tool50and/or allow for visualization via optical window44) when greater than about 5 pounds of force is applied to distal end38in direction37shown inFIG. 3.

Another example force that may act on shaft32is a torque on shaft32when an operator is trying to keep shaft32aligned during insertion. If the operator is rotating shaft32back and forth along the axis40, shaft32must have substantial rigidity to sweep back and forth on the posterior side of sternum13, clear away adhesions, and still “fire” without jamming (e.g., still deploy cutting tool50) on the order of about 5 inches*pound of torque.

Tunneling shaft32may exhibit any suitable shape and dimensions. WhileFIG. 4shows that tunneling shaft32has a substantially circular cross-section, other example cross-section shapes are contemplated. For example, as described further below, in some examples, tunneling shaft32may exhibit an oval cross-section. The outer diameter (in the case of a circular cross-section) or greatest outer dimension (in the case of a non-circular cross-section) of tunneling shaft32may range from about 3 millimeters (mm) to about 15 mm, although other examples are contemplated. The length of tunneling shaft32from proximal end36directly adjacent handle34to proximal end38may range from about 4 inches to about 12 inches, although other examples are contemplated. In examples in which a portion of shaft32is substantially straight from the proximal end36adjacent to handle and then transitions to a curved portion at a point between proximal end36and distal end38, approximately ⅓ (one-third) of the length of shaft32out of proximal end36may be approximately straight. In some examples, shaft32may have a portion that is approximately straight for a length of about 0.5 inches to about 1.5 inches (e.g., in the case of shaft32having an overall length of about 4 inches). In some examples, shaft32may have a portion that is approximately straight for a length of about 3 inches to about 5 inches (e.g., in the case of shaft32having an overall length of about 12 inches). In some examples, approximately ⅔ (two-thirds) of the overall length of shaft32out of proximal end36may be approximately straight. In some examples, shaft32may have a portion that is approximately straight for a length of about 7 inches to about 9 inches (e.g., in the case of shaft32having an overall length of about 12 inches).

Tunneling shaft32defines an inner lumen46that extends from the proximal end36to distal end38. As shown inFIG. 6, inner lumen46runs from tunneling shaft32through handle34, terminating at proximal opening48for handle. Distal end38of tunneling tool32also include optical window44that is shaped to allow for blunt dissection when tunneled through tissue of patient12, e.g., using one or more of the techniques described herein. In the example ofFIGS. 3-6, optical window44has a dome shape for the leading edge to allow for blunt dissection. However, other shapes are contemplated. Optical window44may be formed of a transparent material, for example glass, quartz or clear plastics like polycarbonate (e.g., LEXAN) or acrylic. During an implant procedure, an endoscope or other optical tool may be inserted into lumen46via proximal opening48in handle34and advanced through lumen46to distal end38of tunneling tool32adjacent optical window44. In this manner, a surgeon or other user may visualize the path of distal end38when advanced through tissue of patient12during the insertion of tunnel tool32into patient12.

Additionally, as shown inFIGS. 5A and 5B, tunneling tool30includes cutting tool50at distal end38. Cutting tool50may take the form of a knife blade, scalpel blade, or other tool with a sharp edge51that is configured to cut through tissue, such as, scar tissue, of patient12while tool30is tunneled in the sub-sternal space3of patient12to a target location. Cutting tool50may be configured to be selectively actuated by a surgeon or other user from a recessed position (as shown inFIG. 5A) to a deployed position (as shown inFIG. 5B). When cutting tool50is in the recessed position, the lead or cutting edge of cutting tool50is recessed into distal end38of shaft such that the outer surface of optical window44defines the leading edge of the tool, allowing for blunt dissection of tissue while tunneling shaft32is advanced in sub-sternal space of tissue. Conversely, when cutting tool50is in the deployed position, cutting tool50defines the leading edge of the tunneling shaft32, allowing for tissue, such as, scar tissue, to be cut by the tool by sharp dissection rather than be bluntly dissected.

Any suitable mechanism may be utilized to allow for cutting tool50to be transitioned between the recessed position (FIG. 5A) and deployed position (FIG. 5B). For example, as shown inFIGS. 3, 4, and 6, tunneling shaft32includes blade arms54A and54B (collectively “blade arms54”) parallel to the plane of leading edge51of cutting tool50within tunneling shaft32, which are coupled to cutting tool50at the distal end and extend back to handle34. Blade arms54may be located within tunneling shaft32, inside inner lumen46and adjacent to the inner wall of tunneling shaft32, and/or adjacent to the outer surface of tunneling shaft32(e.g., within tracks recessed into tunneling shaft32). In the example in which blade arms54are located adjacent the outer surface of tunneling shaft32(e.g., within recessed tracks), tunneling tool30may include an outer sheath, e.g., a thin shrink wrap, that assists in securing blade arms in place relative to tunneling shaft32.

Blade arms54are mechanically coupled to handle34such that the actuation of trigger56translates blade arms54along curved shaft32towards distal end38of tool30to transfer mechanical energy to cutting tool50to actuate cutting tool50from the recessed position to the deployed position. In the deployed position, sharp/leading edge51of cutting tool50may extend about 0.25 mm to about 2 mm beyond distal end38of tunneling shaft32. Put another way, in the deployed position, sharp/leading edge51of cutting tool50may extend about 0.25 mm to about 2 mm beyond the leading edge of distal end38, e.g., the outer surface of optical window44, when cutting tool50is in the recessed position.

In some examples, the depression (pulling) of trigger58actuates cutting tool50from the recessed position to the deployed position and cutting tool50may remain in the deployed position until trigger58is released. Alternatively, tunneling member30may be configured such that the actuation of trigger56, e.g., depression or depression and release of trigger56, may result in cutting tool50being actuated from the recessed position to the deployed position and then automatically returned to the recessed position, e.g., after cutting tool50advances forward a pre-set distance. In some examples, a surgeon or other user may hold handle34of tool30stationary when trigger56is depressed to control the length of tissue that is dissected by cutting tool50, which approximately corresponds to the length at which sharp/leading edge51of cutting tool50extends out of distal end38when trigger56is depressed to move cutting tool50into the deployed position. Alternatively, or additionally, a surgeon or other user may advance tunneling shaft32forward by handle34when cutting tool50is held in the deployed position, where the length of tissue dissection by cutting tool50corresponds generally to the length that tunneling shaft32is advanced under the control of the surgeon or other user.

As one example, in the configuration shown inFIG. 6, drive arms54are connected to a spring/hammer/bushing mechanism in handle34that includes scope retention slot58, hammer60, blade bushing62and bushing stop64. When trigger56is pulled, hammer60is retracted against spring66. The trigger56has a cantilever beam56A with a hook. The hook engages the hammer60and drives it against spring66. The beam56A has also the post56B interacting with the slot in the wall of the handle body (not shown). When the trigger56B is advanced sufficiently, the pin56B, guided by the slot raises the hook and releases the hammer60. Upon release, hammer60springs forward impacting blade bushing60to transmit mechanical energy to blade drive arms54until impacting a stop point defined by bushing hard stop64. Bushing hard stop64in handle34prevents blade bushing62from advancing cutting tool50beyond a safe distance out of distal end38of tunneling shaft32.

During a procedure to gain sub-sternal access and create a sub-sternal tunnel in a patient, e.g., to implant a medical device such as lead16, tunneling shaft32may be inserted into the inner lumen of an introducer sheath, e.g., wherein the sheath is sized to extend from approximately distal end38to approximately proximal end36of tool shaft32prior to insertion and advancement of tunneling shaft32in patient12. An example of an introducer sheath41is illustrated inFIG. 19. Sheath41includes a body43and a handle45. Body43of sheath41defines an inner channel. In one example, sheath41may be an open sheath as illustrated and described in U.S. patent application Ser. No. 14/196,298 and U.S. patent application Ser. No. 14/196,443, both of which are incorporated herein by reference in their entireties. In the case of an open sheath, sheath41may include an opening along the length of body43and the inner channel is accessible via the opening anywhere along the length of body43. In another example, sheath41may be a splittable sheath in which body43includes a score or other weakened portion to permit splitting of body43, e.g., as illustrated and described in further detail in U.S. patent application Ser. No. 14/196,443, previously incorporated above. In yet another example, sheath41may be a sheath without any gap or score on body43, in which case sheath41may be removed by slitting the sheath using a slitter, as illustrated and described U.S. patent application Ser. No. 14/196,443, previously incorporated above. Sheath41may have other properties describe above in reference to U.S. patent application Ser. No. 14/196,298 and U.S. patent application Ser. No. 14/196,443 or any commercially available sheaths.

The distal portion of the introducer sheath41may have an open end so as to no obstruct the view through optical window44and deployment of cutting tool50at distal end38of tunneling shaft32. Also, the open end allows for insertion of a lead to the targeted area. Once tunneling shaft32is inserted into the introducer sheath41, distal end38may be inserted into an incision site, e.g., at access site A, and then tunneled superiorly to both create the passageway and then form a sub-sternal tunnel (e.g. along the dotted line ofFIG. 2). During the tunneling, a surgeon or other operator may control the advancement and direction of tunneling shaft32by gripping handle34, which is located external to the body of patient. The surgeon or other operator may view the path of distal end38of tunneling shaft32during the procedure through optical window44using an endoscope or other viewing device inserted within inner lumen46of shaft32. The surgeon or other operator may tunnel through tissue of patient12by way of blunt dissection using distal end38of tunneling shaft with cutting tool in the recessed position. The surgeon or other operator may also selectively deploy cutting tool50, e.g., to cut scar tissue or other areas where blunt dissection (e.g., via the distal end38when cutting tool50is recessed) does not allow for tunneling of tool shaft32. Then, for example, tunneling shaft32of tool30is withdrawn from the patient's body, leaving the introducer sheath41within the sub-sternal tunnel. The operator may pass a medical device, such as the above described lead16, through the sheath lumen, via a proximal opening of the introducer sheath. The surgeon or other operator may then remove the introducer sheath41from the body, leaving lead16within the sub-sternal tunnel, and then remove the sheath from the lead for example, by slitting or splitting the introducer sheath from around lead, according to some embodiments and methods.

FIGS. 18A-18Dare conceptual diagrams illustrating a progression of tunneling tool30during an example tunneling technique in accordance with the disclosure to insert at least a portion of shaft32into the substernal space under sternum13. As described herein, the surgeon or other operator may selectively deploy or recess cutting tool50at distal end38of tunneling shaft32as desired during the tunneling procedure as well as visualize the tissue space through optical window44during the procedure.

As shown inFIG. 18A, a distal portion of tunneling shaft is inserted through an incision site, e.g., at access site A shown inFIG. 2, with cutting tool50in the recessed position at distal end38of tunneling shaft32, with the operator controlling the movement of shaft32by gripping handle34, which is located externally. Handle34remains outside patient12to allow for a surgeon or other operator to maneuver tunneling shaft32along the desired path within the substernal space of patient12. Distal end38of shaft32may be advanced superiorly, e.g., to the position shown inFIG. 18B, to create a portion of a passageway and a sub-sternal tunnel. The surgeon or other operator may view the path of distal end38of tunneling shaft32during the procedure through optical window44using an endoscope or other viewing device inserted within inner lumen46of shaft32. The surgeon or other operator may tunnel through tissue of patient12by way of blunt dissection using distal end38of tunneling shaft with cutting tool50in the recessed position.

At the position shown inFIG. 18B, an operator may determine that a tissue (e.g., a diaphragmatic attachment, pericardium, scar tissue, or connective tissue) is directly adjacent to distal end38of shaft32, e.g., using optical window44. At that position, the operator may deploy cutting tool50to the deployed position (e.g., as show inFIG. 18C) to cut the tissue adjacent to distal end38of shaft32, e.g., via sharp dissection with the leading edge51of cutting tool50. The operator may deploy cutting tool50to the deployed position by depressing trigger56. In some example, during the depression of trigger56, the operator may hold the handle and, thus, shaft32generally in place while the cutting tool51is advanced out to distal end38to the deployed position to cut the adjacent tissue. Once the tissue has been cut by the deployment of cutting tool50, cutting tool50may be retracted back to the recessed position (e.g., automatically or with the release to trigger56) and then advanced by the operator past the cut tissue to the position shown inFIG. 18D, e.g., to provide a path for the placement of lead16in the anterior mediastinum.

As illustrated byFIGS. 18A-18D, an operator may tunnel or otherwise advance a distal portion of shaft32from the incision site to a desired location such that cutting tool50is selectively deployed from the recessed to deployed position, e.g., as needed cut through tissue such as, e.g., diaphragmatic attachment, pericardium, scar tissue, or connective tissue, adjacent to distal end38during the tunneling procedure. Depending on patient anatomy, there may be tissue in the anterior mediastinum or other anatomical location along the pathway of shaft32. During initial insertion, shaft32may penetrate through diaphragmatic attachments that were not dissected with the initial incision. If a patient has not had a previous sternotomy or other procedure, the mediastinal tissue (pericardium, lungs) may move be moving freely. Open space may exist after creating the incision and air is introduced, but expansion of the lungs during breathing may fill this space. Tool30may be particularly useful for patients who have had a previous sternotomy or other open chest procedure. These patients may have severe adhesions to the posterior sternum as result. In such cases, the tissue may be a mixture of pericardium, scar tissue, or connective tissue that forms in response to the injury from the first surgery. When the distal portion of shaft32is introduced into these patients, shaft32may be tunneling and cutting (e.g., via selective deployment of cutting tool50) through this mixture of tissue in order to safely place a lead, such as lead16, as desired within patient12using the example techniques described herein.

As shown inFIGS. 18A-18D, the curvature of tunneling shaft18is such that the distal portion of tunneling shaft is biased towards in the inner surface of sternum13. Additionally, the leading edge51of cutting tool50(illustrated inFIG. 5B, e.g.) extends along a plane that is nonorthogonal (e.g., generally parallel) to the plane of sternum13and outer surface of pericardial sac adjacent tunneling shaft32. Such a configuration may allow for blade arms54to be driven from a mechanism within handle34more easily, e.g., compared to a configuration in which leading edge51of cutting tool50is rotated 90 degrees from that shown inFIG. 3.

Cutting tool50may have any suitable orientation when employed by tunneling tool30. In the example ofFIGS. 3-6, the plane of leading/sharp edge51of cutting tool50is oriented approximately parallel to the central longitudinal axis of handle34and direction in which trigger56is depressed to deploy cutting tool50. Additionally, cutting tool50extends along a plane such that, during normal use tunneling through tissue in sub-sternal space3as described herein, cutting tool50is oriented non-orthogonal (e.g., approximately parallel) to the sternum inner surface, pericardium, and/or heart of patient12.

In addition to or as an alternative to cutting tool50, tool30may include an electrosurgery implement. In such an example, drive arms54may be configured to conduct current and insulated from tissue contact within tunneling shaft32when in a recessed position. An electrical connector may be located, e.g., be included in handle34. In such an example, depressing trigger56may advance the electrosurgical tool out of distal end38temporarily to cauterize or dissect tissue.

FIGS. 7A-7Care schematic diagrams illustrating the distal portion of another example tunneling tool70according to an example of the disclosure.FIGS. 7A and 7Billustrates a cross-sectional view of tunneling tool70taken along cross-section C-C ofFIG. 7C.FIG. 7Cillustrates a cross-sectional view of tunneling tool70taken along cross-section B-B ofFIG. 7A. Tunneling tool70may be substantially the same as tunneling tool30described with regard toFIGS. 3-6, and similar features are similarly numbered. However, unlike tunneling tool30, tool70includes a single blade arm54that translates to transmit mechanical energy from handle34to cutting tool50rather than two blade arms54A,54B as shown for tunneling tool30. Single blade arm54may extend from handle34along curved tunneling shaft to cutting tool50located at distal end38of tunneling tool70. As described previously, blade arm54may be translated (e.g., by depressing trigger56) to move cutting tool50from a recessed position (as shown inFIG. 7A) to a deployed position (FIG. 7B). As illustrated, single drive arm54transmits mechanical energy from handle34to an adjacent side of cutting tool50while the other side of cutting tool50is anchored (e.g., via a pin) to a portion of tunneling shaft32, such as, optical window44. The transmitted energy causes cutting tool50to rotate about the anchoring point to expose the sharp leading edge of cutting tool50to tissue adjacent optical window44. In some examples, the use of a single blade arm54instead of two or more blade arms, such as blade arms54A and54B of tunneling tool30, allows for a reduced diameter of tunneling shaft32.

FIGS. 8A and 8Bare schematic diagrams illustrating the distal portion of another example tunneling tool80according to another example of the disclosure.FIG. 8Ais a cross-sectional view of cutting tool70from a perspective similar to that shown in the example ofFIGS. 7A and 7B, andFIG. 8Bis a side view of the distal portion of tunneling tool80. Tunneling tool70may be substantially the same as tunneling tool30described with regard toFIGS. 3-6, and similar features are similarly numbered. However, rather than tunneling shaft32including a single curved tube within inner lumen, tunneling tool80includes a tunneling shaft32including a first curved tube82and second curved tube84of generally matching curvature. First tube82has a greater diameter than that of the diameter of second tube84such that second tube84is nested, e.g., coaxially, within first tube82. First tube82and second tube84may be sized and configured to be moveable relative each other. In some examples, second tube84may be substantially rigid and made from, e.g., a metal or metal alloy, while first tube82may be constructed to be flexible, e.g., using a flexible plastic material.

In some examples, the movement of first tube82relative to second tube84may be actuated by depression of trigger56to selectively transition cutting tool50between a recessed and deployed configuration, e.g., similar to that described above with regard to tunneling tool30ofFIGS. 3-6. However, rather than employing blade drive arms54to transfer the force from handle34to transition cutting tool50from a recessed to deployed position, in the example ofFIGS. 8A and 8B, actuation of trigger56may move first tube82distally while second tube84remains stationary. Optical window44may be connected to stationary second tube84. As shown inFIG. 8A, cutting tool50may be welded or otherwise connected to metal base86at location81at the distal end of first tube82such that the distal movement of first tube82actuates cutting tool50to extend out of the aperture in optical window44(shown inFIG. 8B) from a recessed to deployed configuration, e.g., to dissect tissue directly adjacent optical window44. In other examples, second tube84is moveable with the actuation of trigger56while first tube82is stationary, where the cutting tool50is connected to second tube84and optical window44is connected to first tube82. In such examples, the movement of second tube84may transition cutting tool50from a recessed to deployed configuration using trigger56.

In some example, tunneling tool80may include a lubricious layer located between the outer surface of second tube84and inner surface of first tube82to promote movement of tubes82and84relative to each other. For example, the outer surface of the second curved tube84to be hard coated with lubricious layer81, e.g., in the form of baked Teflon or other lubricant. Additionally or alternatively, lubricious layer81may be formed on the inner portion of first curved tube82.

In some examples, both first tube82and second tube84may be flexible. In such examples, one or both of first tube82and second tube84(e.g., only second tube84) may include one or more bendable wires (not shown) along a longitudinal length that may be malleable to allow for tunneling shaft to retain a curvature when bent by a user. For example, the bendable wire(s) may be embedded in the walls of first tube82and/or second tube84, or otherwise coupled to first tube82and/or second tube84(e.g., using a heat shrinkable outer sheath). In this manner, the curvature or other shape of shaft32may be modified as desired by an operator to optimize the geometry of shaft32to the anatomy of a particular patient. In some examples, first tube82and/or second tube84may be extruded with a such a bendable wire, e.g., within the side wall of the tube. In some examples, the bendable wire(s) may be a gage21(about 0.0318 inch diameter) 301 stainless steel, ¼ hard wire although other examples are contemplated.

Like that of tunneling tool30, tunneling tool80includes optical window44through which an endoscope or other optical device may employed to allow a surgeon or other user to visualize the space outside of distal end38of tool80during an implant procedure. Likewise, as described above, tunneling tool80includes a semi-circular cutting tool50(e.g., a semi-circular blade) that may be selectively actuated between a recessed and deployed position, e.g., to allow for tunneling tool80to be used for blunt and sharp dissection of tissue, respectively, during implantation in the sub-sternal space3as desired based on the tissue viewable via optical window44. In some examples, semi-circular blade50is welded or otherwise attached in a perpendicular arrangement relative to a circular metal base86.

FIGS. 9A and 9Bare schematic diagrams illustrating the distal portion of another example tunneling tool90from a side and top cross-sectional view according to another example of the disclosure.FIG. 9Bis an illustration of cross-section D-D of tool90inFIG. 9A. Tunneling tool90may be substantially the same as tunneling tool30described with regard toFIGS. 3-6, and similar features are similarly numbered.

In the example ofFIGS. 9A and 9B, tunneling shaft32has a substantially oval (e.g., elongated oval) cross-section in a plane orthogonal to the longitudinal axis of tool90. The oval cross-sectional shape allows for substantially flat surfaces (“top” and “bottom” surfaces in the orientation shown inFIG. 9A) of tunneling shaft32to be adjacent to the sternum inner surface and pericardial sac outer surface when utilized according to the tunneling techniques described herein (as opposed to the rounded top and bottom surfaces of tool30shown inFIGS. 3-6). In some example, the “flat upper” surface of shaft32may be guided or otherwise in contact with sternum inner surface during a tunneling procedure, which may provide for increase stability of tool90in the hand(s) of a surgeon or other operator. Tunneling shaft32includes inner lumen46, blade arms54, and one or more additional lumen92(only a single lumen is numbered inFIG. 9) extending from proximal end36to distal end38of tunneling shaft32.

In some examples, tunneling shaft32may be an extruded tube including the desired number of inner lumen with the desired size, e.g., diameter. The inner lumen(s) of tunneling shaft32be used for insertion of one or more scopes (e.g., a flexible endoscope) for visualization out of optics window44, lead insertion/placement (e.g., in lieu of using an introducer sheath), blade drives arm(s)54, bendable wire(s) for positioning and defining the curvature of tunneling shaft32, stiffening rods, working channels for additional instruments (tools for contrast dyes, electrocautery), and the like. Like the other examples described herein, tunneling shaft32includes optical window44at distal end38to allow a surgeon to visualize the space adjacent to distal end38during a tunneling procedure as well as cutting blade50that may be selectively deployed and retract as need to cut tissue during the tunneling procedure. In the example ofFIGS. 9A and 9B, the lead edge of cutting tool50extends in line with the long axis of the oval cross-section of tunneling shaft32.

FIGS. 10A-10Care schematic diagrams illustrating the distal portion of another example tunneling tool100from a side (FIGS. 10A and 10B) and top cross-sectional view (FIG. 10C) according to another example of the disclosure.FIG. 10Cis an illustration of cross-section E-E of tool100inFIG. 10A. Tunneling tool100may be substantially the same as tunneling tool30described with regard toFIGS. 3-6, and similar features are similarly numbered.

Like that of tool90ofFIGS. 9A and 9B, tool100includes tunneling shaft32having a substantially oval cross-sectional shape. The oval cross-sectional shape allows for substantially flat surfaces (top and bottom surfaces in the orientation shown inFIG. 10A) of tunneling shaft32to be adjacent to the sternum inner surface and pericardial sac outer surface when utilized according to the tunneling techniques described herein (as opposed to the rounded top and bottom surfaces of tool30shown inFIGS. 3-6). As shown inFIGS. 10A and 10C, the leading edge of cutting tool50may extend in a direction substantially perpendicular to the long axis of the oval cross-section of tunneling shaft32, and is located between additional (or “working”) lumen92.FIG. 10Billustrates an example in which the leading edge of cutting tool50may extend an angled, non-perpendicular direction relative to the long axis of the oval cross-section of tunneling shaft32. The angled orientation of cutting tool50allows for the length of the cutting tool50to be longer than, e.g., the length of cutting tool50oriented perpendicular to the long axis of the oval cross-section, resulting in a larger cutting profile.

FIGS. 11A-11Care schematic diagrams illustrating another example tunneling tool110according to an example of the disclosure. Tunneling tool110may be substantially the same as tunneling tool30described with regard toFIGS. 3-6, and similar features are similarly numbered.FIG. 11Billustrates distal end38of tunneling shaft32, which includes optical window44and cutting tool50(shown in the recessed position).FIG. 11Cillustrates a view of tunneling tool110similar to that ofFIG. 11Abut with an outer portion of handle34removed to show, among others, the mechanism employed to allow trigger to be actuated such that mechanical energy is translated cutting tool50, e.g., to selectively deploy cutting tool50for sharp dissection of tissue. Unlike that of tunneling tool30, tool110includes guide member88extending from handle34adjacent to and coplanar with tunneling shaft32. Tunneling shaft32is curved towards guide member88. Handle34has a shape configured to receive fingers of a hand of a surgeon or other operator but may have any other suitable configuration for gripping. When gripped by the surgeon or other operator, a finger such as the index finger may be located in a manner that allows the finger to easily depress and release trigger56.

During a procedure to gain sub-sternal access and create a sub-sternal tunnel in a patient, guide member88may help a surgeon or other operator in advancing tunneling shaft32, once distal end38is inserted into patient12. In some examples, curved distal portion90of guide member88may be configured to ‘ride’ on the skin over the sternum13without binding on the skin during such a procedure. In this manner, guide member88may limit the depth below the sternum13that tunneling shaft32may be advanced during the tunneling procedure. Further, the curvature of tunneling shaft32toward guide member88can cause distal end38to ‘ride’ adjacent an inside surface of sternum13during the superior advancement thereof as an additional aid to the operator. In some example, the distance93between guide member88and tunneling shaft32may be adjusted as desired by a surgeon or other operator, e.g., based on the physical characteristics of a patient. Examples of guide members88employed in a tunneling tool may include those described in U.S. patent application Ser. No. 15/204,579, by Malewicz et al., the entire content of which is incorporated herein by reference.

As shown inFIG. 11C, handle34includes an elastic member like a cable, chain or belt95that is coupled to trigger56. When trigger is pulled, the elastic member drives the slider57which in turn activates the hammer mechanism deploying momentarily the cutting tool50to cut through adhesions. The cutting tool50retracts automatically as in the mechanism described above.

FIG. 12is a schematic diagram illustrating another example tunneling tool120according to an example of the disclosure. Tunneling tool120may be substantially the same as tunneling tool110described with regard toFIGS. 11A-11E, and similar features are similarly numbered. An endoscope or other tool be may be inserted into proximal opening48of handle34and advanced, e.g., through inner lumen46to or near distal end38of tunneling shaft32. The shape of handle34of tool120is different from that of handle34of tool110. For example, handle34is shaped such that when gripped by a hand of a surgeon or other operator, trigger56may be depressed or otherwise actuated by the thumb of that hand rather than a finger such as the index finger in the case of tool110.

FIGS. 13A and 13Bare schematic diagrams illustrating another example tunneling tool130according to an example of the disclosure. Tunneling tool130may be substantially the same as tunneling tool120described with regard toFIG. 12, and similar features are similarly numbered.FIG. 13Bshows proximal opening48in handle34andFIG. 13Ashows endoscope or another tool94inserted within proximately opening48. As described previously, an endoscope or other tool94may be inserted into inner lumen46of tunneling shaft32via opening48in handle34, e.g., to allow for visualization by a surgeon or other operator through optical window44at proximal end38of shaft32during a tunneling procedure. As shown inFIGS. 13A and 13B, trigger56may be shielded by adjacent walls of handle34by recessing trigger56to some extent into the surface of handle, e.g., to protect against unwanted depression of trigger56during a tunneling procedure.

FIG. 14is a schematic diagram illustrating another example tunneling tool140according to an example of the disclosure. Tunneling tool140may be substantially the same as tunneling tool110described with regard toFIGS. 11A-11E, and similar features are similarly numbered. Unlike tunneling tool110, handle34of tunneling tool140includes trigger guard96to prevent trigger56from being depressed accidently by a surgeon or other operator during a tunneling procedure.

FIGS. 15A-15Care schematic diagrams illustrating another example tunneling tool according to an example of the disclosure. Tunneling tool150may be substantially the same as tunneling tool110described with regard toFIGS. 11A-11E, and similar features are similarly numbered. Unlike tunneling tool110, the vertical portion of handle34of tunneling tool140is angled further towards distal end38of tunneling shaft38.

FIGS. 16A-16Eare schematic diagrams illustrating another example tunneling tool160according to an example of the disclosure.FIGS. 16A and 16Billustrate two different perspective views of tool160.FIGS. 16C and 16Dillustrate distal end38of tunneling shaft32with optical window44as well as cutting tool50in the recessed and deployed positions, respectively.FIG. 16Eillustrates a cross-sectional view of handle34.

While tunneling shaft32of tool120is substantially straight from proximal end26to distal end38, in some examples tunneling shaft32may be curved, e.g., like that of tunneling shaft32of tool30shown inFIGS. 3-6. Tunneling shaft32includes inner lumen46that is open and may accept a rigid or flexible scope through proximal opening48in handle34. Distal end38of tunneling shaft32may be made of clear or otherwise transparent material so as to enable direct visualization of the tissue through which shaft32is advancing. Handle34houses the mechanism and include trigger56which may extend the cutting tool50from a recessed (FIG. 16C) to a deployed position (FIG. 16D). Distal end38is generally blunt when cutting tool50is in a recessed position, e.g., to prevent wounding of vital organs like mammary arteries or lungs during a tunneling procedures.FIGS. 16C and 16Dshow distal end38as a beveled tip with optical window44. However, other distal end geometries are contemplated. For example,FIG. 17illustrates another example in which distal end38includes a domed or sphere-shaped tip, which may be made of a clear or otherwise transparent material.

As shown inFIG. 16C, cutting tool50is recessed in the channel98at distal end38when in a recessed position. Tunneling shaft32also includes additional lumens102A and102B, which may be used, e.g., for insufflation, irrigation, adding contrast, flushing lens, removing air pockets, and the like.

With reference toFIG. 16E, proximal end104(which may be similar to that of blade arm(s)54) of cutting tool is engaged to spring loaded slider106. A sloped surface108of slider106serves as a cam. Lever112pivots around first post114, and its stroke is limited by second post116which travels inside the slot of the handle34. Tip118of the lever112engages the slider slope108to drive cutting tool50forward when necessary to a deployed position by depressing lever112of trigger56. In such an example, cutting tool50may remain in a deployed position until trigger56is no longer depressed, e.g., as opposed to automatically retracting to a recessed position when trigger56is depressed.