Patent Publication Number: US-2021162197-A1

Title: Percutaneous conduit deployment method and instruments therefor

Description:
RELATED APPLICATIONS 
     This application claims priority benefit of U.S. Provisional Application Ser. No. 62/652,368 filed 4 Apr. 2018, the contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention in general relates to medical devices and systems and in particular, to create an appropriate pathway through the skin to serve as a conduit through which a medical appliance or a percutaneous access device (PAD) can be implanted and a method of deployment thereof. 
     BACKGROUND OF THE INVENTION 
     Heart disease is one of the leading causes of death. Currently, medical science cannot reverse the damage done to the cardiac muscle by heart disease. One solution for such patients is a heart transplant. However, the number of cardiac patients in need of a heart transplant far exceeds the limited supply of donor hearts available. 
     The scarcity of human hearts available for transplant, as well as the logistics necessary to undertake heart transplant surgery, makes an implantable cardiac assist device a viable option for many heart patients. A blood pump can be surgically implanted, or adjacent to, the cardiovascular system to augment the pumping action of the heart. The blood pump is sometimes referred to as a mechanical auxiliary ventricle assist device, dynamic aortic patch, balloon pump, mechanical circulatory assist device, or a total mechanical heart. Alternatively, the blood pump can be inserted endovascularly. 
     Typically, the blood pump systems include a driveline that serves as a power and/or signal conduit between the blood pump internal to the patient and a controller/console external to the patient. Often, a percutaneous access device (PAD) can be surgically implanted at the location in the skin where the driveline penetrates the skin to provide a through-the-skin coupling for connecting the supply tube to an extra-corporeal fluid pressure source. Electrical leads from electrodes that may be implanted in the myocardium are likewise brought out through the skin by means of the PAD. The aortic valve status or any cardiovascular parameter that is associated with this status can be employed to control the fluid pressure source to inflate and deflate the inflatable chamber in a predetermined synchronous relationship with the heart action. 
     The surface of the driveline, or of the optional PAD used in cardiac assist systems may have characteristics which promote the formation of a natural biologic seal between the skin and the device to form a barrier to microbial invasion into the body at the skin penetration site. More generally, medical appliances which are implanted so as to cross the skin surface and therefore violate the “barrier function” of the skin, may also illustratively be used for other medical purposes including peritoneal dialysis catheters, chronic indwelling venous access catheters, neurologic prostheses, osseointegrated prostheses, drug pumps, and other treatments that require skin penetration. 
       FIG. 1  illustrates wearable and implanted components of an exemplary prior art cardiac assist system. A PAD  10  serves as an attachment point for an external supply line  12  that supplies air or fluid from a wearable external drive unit (EDU)  14 . The EDU  14  is powered by a wearable battery pack  16 . Inside the body of the patient, a drive line  18  is attached to the PAD  10  and provides an air or fluid conduit to a cardiac assist device  20 . 
     While conventional aortic balloon pumps and other implanted assist devices are well known to the art, driveline infection remains one of the most frequent and costly adverse events, associated with implanted assist devices, at the percutaneous access device (PAD). Driveline infections may be predisposed to systemic infections due to ascending microbial invasion. 
     Ventricular Assist Device (LVAD) driveline infections (DLI) are the most common type of infection associated with implantable pumps. These infections occur at the skin penetration site because current devices require an external power source with energy supplied via a tunneled percutaneous driveline. Driveline infections frequently occur because the driveline exit site creates a conduit for entry of bacteria. DLI, along with gastrointestinal bleeding (GIB) and stroke, are the leading causes of unplanned readmission for patients with an LVAD 
     There is a continuing need for internal drivelines for implanted devices and methods of implantation thereof that significantly minimize or inhibit the risk of driveline and exit site infections 
     SUMMARY OF THE INVENTION 
     A system for deploying a percutaneous conduit from within the skin of a patient in the subcutaneous layer includes a tunneler having an elongated passer section, the elongated passer section having a proximal end terminated with an attachment feature for the percutaneous conduit and a distal end terminated in a tunneling head. A central needle is in the tunneling head in a coaxial channel in the elongated passer section containing a wire for advancement of the central needle. A cylindrical trephine blade is attached to the central needle, where when the central needle is advanced through and pierces an outer layer of the patient&#39;s skin in an outward direction away from the patient, and the central needle defines a longitudinal axis of trephination or cylindrical cut of the cylindrical trephine blade in the patient&#39;s skin that is used for placement of a medical appliance or a percutaneous access device (PAD). 
     A system for deploying a percutaneous conduit from within the skin of a patient in the subcutaneous layer includes a tunneler having an elongated passer section, the elongated passer section having a proximal end terminated with an attachment feature for the percutaneous conduit and a distal end terminated in a tunneling head. A central needle with a cam is in a central channel of the tunneling head, where a lower chamber in the form of a semicircle off of the central channel allows for partial upward movement of the cam to a first stop, and an upper chamber in the form of a semicircle off of the central channel that allows for partial upward movement of the cam to a second stop. A coaxial channel in the elongated passer section contains a wire for advancement and twisting of the central needle. A cylindrical trephine blade is actuated by the cam of the central needle in the upper chamber, where when the central needle is advanced through and pierces an outer layer of the patient&#39;s skin in an outward direction away from the patient, and the central needle defines a longitudinal axis of trephination or cylindrical cut of the cylindrical trephine blade in the patient&#39;s skin that is used for placement of a medical appliance or a percutaneous access device (PAD). 
     A method for deploying a percutaneous conduit from within the skin of a patient in the subcutaneous layer includes making a sub cut in the subcutaneous layer, inserting a tunneler in the sub cut, and advancing the tunneling head to form a tunnel in the subcutaneous layer to an exit location. Subsequently, a central needle is deployed, or following a pre-positioned central guidewire, to pierce through the skin of the patient. A cylindrical trephine blade is deployed to make a cylindrical cut in the skin, and the tunneler is pulled or pushed out of the patient to expose the driveline and for positioning the medical appliance or PAD in the cylindrical cut. The tunneler is then detached from the driveline 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  illustrates prior art wearable and implanted components of a cardiac assist system with a percutaneous access device (PAD) and internal driveline; 
         FIGS. 2A-2E  are a series of partial cutaway side perspective views showing the internal implantation and deployment of an internal driveline and an optional PAD in the subcutaneous layer below the dermis and above the fascia layer in accordance with embodiments of the invention; 
         FIG. 3  is an exploded sectioned view of a tunneler tip and corresponding central lead needle, and cylindrical trephine blade in accordance with an embodiment of the invention; 
         FIGS. 4A-4D  are a series of side perspective cross-sectional views showing the internal implantation and deployment of an internal driveline using the tunneler tip of  FIG. 3  in accordance with an embodiment of the invention; 
         FIGS. 5A-5E  are a series of detailed cross-sectional side views of the tunneler tip of  FIG. 3  illustrating the deployment of the central lead needle and cylindrical trephine blade in a patient according to an embodiment of the invention; 
         FIG. 6  is a side perspective cross-sectional view of a quick locking fastener according to an embodiment of the invention; and 
         FIG. 7  is a side perspective cross-sectional view of a tunneler to central lead needle locking mechanism according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An interior driveline and driveline deployment system according to the present invention has utility to mitigate the risk of infections for a variety of implanted medical appliances with a percutaneous conduit. While the present invention is further detailed with respect to a cardiac assist device driveline, it is appreciated that the present invention informs the deployment of various implanted medical devices having a percutaneous conduit, such devices also illustratively include a percutaneous central catheter (PICC), a colostomy port, a peritoneal dialysis catheters, a dialysis conduit, an insulin pump, neurologic prostheses, osseointegrated prostheses, drug pumps, and other treatments that require skin penetration or any connection between an internal organ or cavity and an extracorporeal device. Embodiments of the inventive interior driveline and driveline deployment system allow for the deployment of a driveline and an optional corresponding percutaneous access device (PAD) from within the tissue layers below the dermis, prior to exiting the body of a patient. It has been surprisingly found that deployment related infections can be effectively eliminated with resort to the present invention. The counterintuitive interior introduction of the driveline and corresponding PAD of the present invention thereby precludes entrainment introduction of exogeneous pathogens associated with the traditional approach for insertion of a driveline with an exterior to interior directionality relative to the subject corpus. 
     In a specific embodiment the interior driveline (DL) or percutaneous conduit incorporates a polymeric or polyester velour. In specific inventive embodiments the textured contacting outer surfaces is based on Integrally Textured Polymer (ITP) formed as a membrane and in an exemplary embodiment an Integrally Textured (IT) Polyurethane. Other suitable materials for an ITP illustratively include polyamides, polyimides, polyesters, polycarbonates, copolycarbonate esters, polyethers, polyetherketones, polyetherimides, polyethersulfones, polysulfones, polyvinylidene fluoride, polybenzimidazoles, polybenzoxazoles, polyacrylonitrile, cellulosic derivatives, polyazoaromaties, poly(2,6-dimethylphenylene oxide), polyphenylene oxides, polyureas, polyurethanes, polyhydrazides, polyazomethines, polyacetals, cellulose acetates, cellulose nitrate, ethyl cellulose, styrene-acrylonitrile copolymers, brominated poly(xylylene oxide), sulfonated poly(xylylene oxide), tetrahalogen-substituted polycarbonates, tetrahalogen-substituted polyesters, tetrahalogen-substituted polycarbonate esters, polyquinoxaline, polyamideimides, polyamide esters, polysiloxanes, polyacetylenes, polyphosphazenes, polyethylenes, polyphenylenes, poly(4-methylpentene), poly(trimethylsilylpropyne), poly(trialkylsilylacetylenes), polyureas, polyurethanes, blends thereof, block copolymers thereof; a fiber or particle filled forms of any of the aforementioned. 
     Furthermore, the surface of the medical appliance or PAD used in inventive embodiments promotes the formation of a natural biologic seal between the skin and the device to form a barrier to microbial invasion into the body via the skin penetration site. Embodiments of the PAD may also illustratively be used cardiac assist devices and for other devices including peritoneal dialysis catheters and chronic indwelling venous access catheters that require skin penetration. The percutaneous access device used with some inventive embodiments of the percutaneous conduit are pre-coated with a recipient&#39;s dermal fibroblasts. These dermal fibroblasts inhibit epidermal down growth, preventing sinus tract formation along the driveline; and an environment that supports microbial growth. 
     Embodiments of the percutaneous conduit may be treated with a primary coating to promote long-term stability and therefore any implanted device anchored thereto. Such coating substances illustratively include heparin, antibiotics, radiopaque agents, anti-thrombogenic agents, anti-proliferative agents, pro-proliferative agents, anti-angiogenic agents, and pro-angiogenic agents; each alone, or in combination. It is further appreciated that a secondary coating overlying the first coating is provided to promote sustained release of the underlying coating substance. Such secondary coatings illustratively include polylactic acid, polyglycolic acid, polyethylene oxide, polycaprolactone, polydioxanones, combinations thereof, and co-polymers thereof. 
     In certain inventive embodiments, the interior driveline may be formed from a material that induces immunocompatible granulation tissue overgrowth thereon. Coatings operative herein illustratively include poly- L -lysine (PLL), polylmethyl coguanidine-cellulose sulphate (PMCG)-CS/PLL-sodium alginate (SA), polyethylenimine, poly(dimethyldiallylammonium chloride), chitosan, polyacrylacid, carboxymethylcellulose, cellulose sulfate, pectin, and combinations thereof to form multilayers. It is appreciated that such coatings are readily impregnated with compounds that reduce the immune cascade or alternatively, enhance the inflammatory cascade, these illustratively include heparin and factor H. 
     Referring now to the figures,  FIGS. 2A-2E  are a series of partial cutaway side perspective views showing a system  30  for the internal implantation and deployment of an embodiment of the internal driveline  52  and an optional PAD  62  in the subcutaneous layer  42  below the dermis  44  and above the fascia layer  46 . In  FIG. 2A  a sub cut is made for a subcutaneous tunnel that is formed in the subcutaneous layer  42  when a tunneler is inserted in and advanced through the sub cut. The tunneler has an elongated passer section  32  with a proximal end terminated with an attachment feature  54  illustratively including screw threads, and a distal end terminated in a tunneling head  36 . The attachment feature  54  may be used to secure a primary “T” handle  34  that is used to push the tunneler through the subcutaneous layer  42  to a desired exit site. The elongated passer section  32  may have a coaxial channel with a wire  40  therein. The wire  40  may be used to advance a central needle  38  connected to the distal end of the wire  40  in the tunneling head  36 . In  FIG. 2B  the central needle  38  is advanced through and pierces the dermis  44  in an outward direction away from the patient. The central needle  38  defines a longitudinal axis of the trephination or cylindrical cut in the dermis  44  where the medical appliance, with the optional PAD  62 , will be inserted as shown in  FIG. 2E . In  FIG. 2C  as the central needle  38  is further advanced through the dermis  44 , and the cylindrical trephine blade  50  begins to deploy from the tunneling head  36  and pierce the dermis  44 . In  FIG. 2D  a secondary “T” handle  56  is attached via an engagement feature or eyelet  48  in the central needle  38  and is used to pull and twist (arrow  60 ) the trephine blade  50  through the dermis  44  with the removed cored tissue  58  held by the tunneling head  36  within the cylindrical area of the trephine blade  50 . Also shown in  FIG. 2D , a driveline  52  is attached to the attachment feature  54  of the elongated passer  32  and pulled through the subcutaneous layer  42  to the newly created skin opening. As shown in  FIG. 2E , the driveline  52  is continued to be pulled out of the patient until the prior secured optional PAD  62 , which concentrically surrounds the driveline  52 , is pulled into the newly created skin opening. At this point the driveline  52  is in the final desired position. The driveline  52  is subsequently attached to the implanted device (not shown). It is appreciated that the eyelet  48  is amenable to engage a cam (not shown) or similar engagement mechanism to secure the secondary T handle  56 . Additionally, not shown, a hollow channel or eyelet can allow a guidewire to serve to define a percutaneous path to be followed thereafter by the needle  38 . 
     In some inventive embodiments, a tracking system is deployed that includes two or more receivers to detect the position of fiducial markers (e.g., retroreflective spheres, active light emitting diodes (LEDs), or radiofrequency identification tags) arranged on a subject body and the inventive tunneler apparatus. The fiducial markers collectively define a fiducial marker array. In some inventive embodiments, each fiducial marker has a unique arrangement of fiducial markers, or a unique transmitting wavelength/frequency to distinguish one marker array from another. An example of an optical tracking system operative herein is described in U.S. Pat. No. 6,061,644. With resort to a tracking system computer that includes tracking hardware, software, data, and utilities to determine the position and orientation (POSE) of objects (e.g., receipt tissue and instruments) in a local or global coordinate frame, an inventive method is amenable to being conducted under autonomous or semiautonomous robotic control. The POSE of the objects is collectively referred to herein as POSE data, where this POSE data may be communicated to the device computer through a wired or wireless connection. Alternatively, the device computer may determine the POSE data using the position of the fiducial markers detected from the optical receivers directly. 
     The POSE data is determined using the position data detected from the receivers and operations/processes such as image processing, image filtering, triangulation algorithms, geometric relationship processing, registration algorithms, calibration algorithms, and coordinate transformation processing. For example, the POSE of an optically tracked digitizer probe with an attached probe fiducial marker array is calibrated such that the probe tip is continuously known as described in U.S. Pat. No. 7,043,961. Registration algorithms may be executed to determine the POSE and coordinate transforms between recipient tissue, pre-operative tissue data, a fiducial marker array, a surgical plan, a surgical robot, and/or tracking system using the registration methods as described above. 
       FIG. 3  is an exploded sectioned view of an inventive embodiment of a tunneler head  100  and corresponding tunneler tip  102 , central lead needle  116 , and cylindrical trephine blade  124  (shown in longitudinal section with a long side ( 124 L) and short side ( 124 S). The cylindrical trephine blade  124  is designed to be carried within tunneler tip  102  of the tunneler head  100  in slots ( 112 L,  122 S). The cylindrical trephine blade  124  is secondarily deployed to incise a core of dermis/epidermis at an exit site. The anti-incision end (flat end) of the long side ( 124 L) engages with a cam  122  on the central needle  116  as is best shown in  FIGS. 5D and 5E . The tunneler tip  102  has a central channel  104  that houses the central needle  116 . A lower chamber  106  in the form of a semicircle off of the central channel  104  allows for partial upward movement of the cam  122  with a first stop  108 . In order to further advance the central needle  116 , the cam  122  needs to be rotated into the semicircle shaped upper chamber  110 . As best shown in  FIGS. 5D and 5E , the cam  122  then engages the long side ( 124 L) of the cylindrical trephine blade  124  to provide secondary deployment of the cylindrical trephine blade  124  from slots ( 112 L,  112 S) until a second stop  114  is reached that halts further advancement of the central needle  116  and the cylindrical trephine blade  124 . 
       FIGS. 4A-4D  are a series of side perspective cross-sectional views showing the internal implantation and deployment of an internal driveline  52  using the tunneler tip  102  of  FIG. 3 . In  FIG. 4A  the primary “T” handle  34  is connected to the distal end of the elongated passer  32 , while the proximal end of the passer  32  is connected to the tunneler tip  102  with the tip  120  of the central needle  116  beginning to pierce the dermis  44  of the patient. In  FIG. 4B  wire  40  is advanced to push the central needle  116  through the dermis  44 . The primary “T” handle  34  is removed from the distal end of the passer  32 , and a secondary “T” handle  56  is attached to the central needle  116  via the engagement feature or eyelet  118  to pull the central needle  116  completely through the dermis  44 .  FIG. 4C  shows the deployment of the cylindrical trephine blade  124  into the dermis  44 , and the attachment of the internal driveline  52  to the distal end of the passer  32 .  FIG. 4D  illustrates the passing of the tunneler tip  102  completely through the dermis  44  with a cored section of removed skin  58  held by the cylindrical trephine blade  124 . 
       FIGS. 5A-5E  are a series of detailed cross-sectional side views of the tunneler tip  102  of  FIG. 3  illustrating the deployment of the central lead needle  116  and cylindrical trephine blade  124  in a patient.  FIG. 5A  illustrates the tip  120  of the central needle  116  just prior to piercing the dermis  44 . In  FIG. 5B , the cam  122  advances in the lower chamber  106  until the first stop  108  with the central needle  116  fully passing through the dermis  44 . In  FIG. 5C , the secondary “T” handle  56  is joined to the central needle  116  via an engagement feature or eyelet  118 . In  FIG. 5D , the central needle  116  is twisted (arrow  126 ) with the secondary “T” handle  56  to rotate the cam  122  into the upper chamber  110  to engage the long side of the cylindrical trephine blade  124 L. In  FIG. 5E  the central needle  116  is pulled with the secondary “T” handle  56  to expose the cylindrical trephine blade  124  and to create a trephination or cylindrical cut in the dermis  44  where the PAD will be placed. 
     It is appreciated that while the cylindrical trephine is described as being advanced through the dermis with a twisting or rotating action, a unidirectional or oscillating action, may be introduced via mechanisms contained in the tunneler itself, or a detachable external or internal rotational mechanism. In specific inventive embodiments the size of the cylindrical trephine is appropriately sized to create a slight interference between the dermal/epidermal trephination incision and the surface of the medical appliance or PAD to encourage and generate tissue ingrowth into the device. Furthermore, not to be limited to a specific theory, but it is believed that potential gaps between the trephination incision and the surface of the medical appliance or PAD encourage the formation of reservoirs which serve to accumulate reactive wound fluids containing dissolved molecules utilized by bacteria to support infective colonization and thereby interfere with the rapid integration of dermal fibroblasts with the surface of the medical appliance or PAD. 
     In a specific inventive embodiment, in lieu of the central flat or round needle, a guide wire can be separately placed to pierce the skin at the planned skin exit site and a hollow channel within the tunneler head may then follow the pathway of the guidewire outwardly from the patient, where the pathway may be at any arbitrary angle of incidence to the epidermis. In other words, the needle or guidewire may be placed from external-to internal or from internal-to-external, but the remainder of the tunneler, trephine, medical appliance or PAD are passed from the internal-to-external. 
     In a specific inventive embodiment, a collapsible/expandable trephine with a cannulated central channel can, in its collapsed state, follow the guidewire from outside the skin, past the epidermis, at any arbitrary angle of incidence to the epidermis, and dermis into the subcutaneous tissue, thence open to an expanded state, and subsequently can be pulled externally through the subcutaneous tissue layer/dermis layer and epidermis layer. Thusly, a skin trephination can be excised in a fashion which will provide accurate intimate coaptation of skin layers against the medical appliance in the service of promoting healing between skin layers and the medical appliance. 
     While it is appreciated that a guidewire introduced from external-to-internal might contaminate the needle tract from the introduced external wire, it is understood that this contaminated skin would be excised by the cylindrical trephine with the core of removed skin tissue. Moreover, while the needle or guidewire may be placed from external-to internal or from internal-to-external, the remainder of the tunneler, trephine, medical appliance or PAD are passed, with appropriate sheathing or other protective mechanisms, either from the internal-to-external direction or the external-to-internal direction. 
       FIG. 6  is a side perspective cross-sectional view of a quick locking fastener  130 . 
       FIG. 7  is a side perspective cross-sectional view of a tunneler to central lead needle locking mechanism  140 . The tunneler tip head  142  has a series of pawls  144  that are complementary to pawls  144 ′ along the side of the central needle  146 . Under tunneler tip head  142  compression, the tip is locked to the serrated edges of the complementary pawls  144 ′ of the central needle  146 . Pressure on the tunneler tip head  142  is relieved prior to advancing the central needle  146 . Advancing the needle (and any hand motion) will permit the teeth of the pawls  144  to dislodge from the complementary pawls  144 ′ and permit advancement of the central needle  146 . 
     Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference. 
     The foregoing description is illustrative of particular embodiments of the invention but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.