Patent Publication Number: US-11027103-B2

Title: Conduit device and system for implanting a conduit device in a tissue wall

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of co-pending U.S. patent application Ser. No. 15/058,703, filed on Mar. 2, 2016, which is a continuation of U.S. patent application Ser. No. 14/475,068, now U.S. Pat. No. 9,308,015, which is a continuation of U.S. patent application Ser. No. 13/845,960, filed on Mar. 18, 2013, now U.S. Pat. No. 8,858,489, which is a continuation of U.S. patent application No. Ser. No. 12/901,810, filed on Oct. 11, 2010, now U.S. Pat. No. 8,430,836 issued on Apr. 30, 2013, which is a continuation of U.S. patent application Ser. No. 11/739,151, filed on Apr. 24, 2007, now U.S. Pat. No. 7,846,123 issued on Dec. 7, 2010, which are hereby incorporated by reference in their entireties herein. 
    
    
     FIELD OF INVENTION 
     This invention relates to devices and methods for creating and maintaining a fluid conduit to establish fluid communication between opposing surfaces of a tissue wall. 
     BACKGROUND OF THE INVENTION 
     Construction of an alternative conduit between the left ventricle and the aorta (an apicoaortic conduit, or AAC) to create a double-outlet left ventricle (LV) has been successfully employed to treat a variety of complex congenital LV outflow obstruction (fibrous tunnel obstruction, aortic annular hypoplasia, tubular hypoplasia of the ascending aorta, and patients with diffuse septal thickening, severe LV hypertrophy and a small LV cavity) as well as adult-onset aortic stenosis in patients with complicating preoperative conditions (previous failed annular augmentation procedures, previous infection, previous CABG with patent anterior internal mammary artery grafts, and a porcelain ascending aorta). 
     However, the AAC insertion procedure has been poorly accepted, primarily because of early valve failures using first-generation bioprostheses as well as the success of direct LVOTO repair and aortic valve replacement. In the United States, despite an aging population, the unadjusted mortality for isolated aortic valve operations in 2001 remained under 4%. Further, the AAC insertion operation, with or without cardiopulmonary bypass, has not been as technically straightforward as direct aortic valve replacement. For most surgeons, AAC insertion is not a familiar operation and is of historical interest only. 
     Nonetheless, several studies have demonstrated that AAC insertion successfully lessens the LV-aortic pressure gradient, preserves or improves ventricular function and maintains normally distributed blood flow through the systemic and coronary circulation. While there have been several techniques described, the most commonly employed method is the lateral thoracotomy approach with placement of the AAC to the descending aorta. Other techniques include a median sternotomy approach with insertion of the distal limb of the AAC to the ascending aorta, to the transverse part of the aortic arch, or to the intra-abdominal supraceliac aorta. 
     In general, the thoracic aorta and the left ventricle apex are exposed through a left lateral thoracotomy, and a needle is passed through the apex and into the left ventricle. While the connector is still spaced apart from the apex, the sutures that will fix the connector to the apex are threaded through a cuff on the connector and through the apex in a matching pattern. The cuff is set back from the end of the connector by 1-2 centimeters to allow the end of the connector to extend through the heart muscle and into the left ventricle. Once the sutures are in place, a ventricular coring device is used to remove a core of ventricular muscle, and the pre-threaded sutures are then pulled to draw the connector into the opening until the cuff comes to rest: on the apex. The sutures are tied off, and additional sutures may be added. Either before or after this procedure, the opposite end of the connector is attached to a valved conduit which terminates at the aorta. 
     The current techniques and technology available to perform AAC insertion were originally designed to be performed on-pump; either with an arrested or fibrillating heart. While off-pump cases have been described, they can be technically difficult due to the shortcomings of presently available conduits and systems for installing such conduits. For example, because existing conduits require the use of sutures to reliably secure the connector in place, it is often difficult for surgeons or other clinicians to insert such sutures reliably in active cardiac and/or vascular tissue. 
     Some devices and methods have been devised to install an AAC conduit, such as those described generally in U.S. patent application Ser. No. 11/251,100, filed on Oct. 14, 2005, and U.S. patent application Ser. No. 10/915,691, filed on Aug. 11, 2004, both of which are hereby incorporated herein in their entirety by reference. However, these AAC conduit devices and installation systems rely on the use of a flexible flange that is inserted through a pre-defined aperture in the ventricular apex. Thus, such methods require the use of a hemostatic device (such as an occlusion balloon and/or “umbrella” device) to prevent blood loss from the aperture during installation of the AAC conduit. 
     SUMMARY OF THE INVENTION 
     Various embodiments of the present invention provide an improved system and method for the insertion of a conduit (such as an AAC conduit) that will significantly simplify the in vivo insertion of a graft into the beating cardiac apex or other tissue walls (such as other areas of the heart including the anterior, lateral, posterior walls of the left or right ventricle, the left or right atrium, the aortic wall, ascending, transverse, or descending, or other blood vessel walls), such that vascular conduit insertions (including AAC procedures) may be rendered far more attractive to clinicians. Because vascular conduits and systems of the present invention may be used to create alternate outflow tracts in “off-pump” procedures, the embodiments of the present invention may effectively reduce and/or negate the detrimental effects of both cardio-pulmonary by-pass (CPB) and global cardiac ischemia. Additionally, because some conduit embodiments of the present invention (for AAC procedures, for example) may be inserted into a ventricular or atrial free wall or cardiac apex, the conduction system of the heart may be avoided, along with the native coronary arteries and grafts from previous surgical revascularization. In some embodiments of the present invention, wherein the system is used to implant an AAC, a small size valve (19 to 21 mm for typical adult body surface areas) is usually adequate; as the effective postoperative orifice is the sum of the native and prosthetic aortic valves. Further, the present invention provides vascular conduits that may be compatible with newer generation biologic valves, such that valved conduit failure is far less likely. Various embodiments of the present invention may also provide general conduit devices (and systems for implanting) suitable for establishing fluid communication between opposing surfaces of tissue walls in a variety of applications, including the establishment of a fluid conduit through the tissue wall of a mammalian urinary bladder. 
     In one exemplary embodiment, a system is provided for implanting a conduit device (such as an AAC component) in a tissue wall having a first surface and an opposing second surface. According to some embodiments, the system comprises an outer tube defining a guide aperture extending axially through the outer tube and an attaching device extending from a distal end of said outer tube. The attaching device is configured for advancing along a helical path at least partially through the tissue wall such that at least a portion of the attaching device becomes disposed substantially between the first surface and the opposing second surface of the tissue wall when the outer tube is rotated relative to the first surface of the tissue wall. The attaching device, in some system embodiments, comprises at least one of a helical static coil and a helical elastic spring having a sharpened distal end adapted for piercing the tissue wall as the outer tube is rotated relative to the first surface of the tissue wall. According to some such embodiments, the attaching device may define a radially-expanding helix as the attaching device extends away from the distal end of the outer tube. 
     In some embodiments, the system also comprises a ring operably engaged about an outer surface of the outer tube and configured for cooperating with the attaching device such that at least a portion of the tissue wall is secured between the attaching device and the ring so as to operably engage said outer tube with the tissue wall. According to some such embodiments, the system may further comprise a plurality of ridges disposed on the outer surface of the outer tube. In such embodiments, the ring comprises at least one deformable pawl member operably engaged therewith for releasably engaging the plurality of ridges on the outer surface of the outer tube. In some other embodiments, the system may comprise threading on at least a portion of the outside surface of the outer tube and corresponding threading on at least a portion of an inside surface of the ring. The threading may thus be configured to cooperate for axially securing the ring relative to the outer tube. Furthermore, some system embodiments may further comprise a nut operably engaged about an outer surface of the outer tube and proximal to the ring. The nut may comprise threading on at least a portion on an inside surface thereof, wherein the threading may be configured for cooperating with the threading on at least a portion of the outside surface of the outer tube. Furthermore, the nut may be configured for cooperating with the ring to advance the ring towards the distal end of the outer tube. 
     In some embodiments, various system components, such as the outer tube and the ring, may be configured to conform to and/or establish a substantially fluid-tight seal with at least a portion a surface of the tissue wall. For example, in some embodiments, the system may comprise a sealing member operably engaged with a distal end of the ring. According to such embodiments, the sealing member may be configured for establishing a substantially fluid tight seal between the ring and the first surface of the tissue wall. In some embodiments, the system may be configured to cooperate and/or operably engage a tissue wall comprising a substantially curved tissue wall. According to some such embodiments, the ring may comprise a frusto-conical assembly configured for receiving at least a portion of the substantially curved tissue wall so as to form a substantially fluid-tight seal between the frusto-conical assembly and the tissue wall. 
     In some embodiments, the system further comprises an inner tube configured for insertion into the guide aperture defined by the outer tube. According to such embodiments, the inner tube defines a conduit aperture extending axially therethrough. Furthermore, in some such embodiments, the outer tube may comprise a first securing device operably engaged with a proximal end of the outer tube and the inner tube may comprise a complementary second securing device operably engaged with a proximal end of said inner tube. Thus, according to such embodiments, the second securing device may be configured for selectively operably engaging the first securing device so as to operably engage the inner tube with the outer tube to install and maintain the conduit. 
     In some embodiments, the system may also comprise a coring device configured for advancing through the conduit aperture defined by the inner tube and through the tissue wall to define an aperture therein by removing a tissue core. The coring device may be further configured for carrying the inner tube through the aperture such that the inner tube extends at least partially through the aperture so as to establish fluid communication between the first and second surfaces of the tissue wall. The coring device may define a coring bore extending axially therethrough and configured for receiving the tissue core removed by the coring device. In some embodiments, the coring device may further comprise a piercing rod slidably advancable and retractable within the coring bore. The piercing rod may further comprise a retrieval device operably engaged with a distal end thereof and configured for axially retaining the tissue core removed by the coring device. Thus, in some embodiments, the piercing rod may be configured for advancing so as to pierce the tissue wall prior to removal of the tissue core and/or retracting after removal of the tissue core such that the tissue core is retrievable via a proximal end of the coring device. In some such embodiments, the coring device may further comprise a handle operably engaged with the proximal end of the coring device. The handle may define a tissue core chamber in communication with the coring bore, the tissue core chamber configured for receiving the tissue core retrieved by the retraction of the piercing rod. Furthermore, in some such embodiments, at least a portion of the handle may comprise a transparent material such that the tissue core received therein is visible from a position outside the handle. 
     The various embodiments of the present invention may thus be configured for implanting a conduit device that is adapted for providing a conduit for a medical procedure. Such procedures may include, but are not limited to: bypass; cardiac valve repair or replacement; attachment of a ventricular assist device; establishment of an apicoaortic conduit (AAC) and combinations of such procedures. 
     Use of this new conduit device, system, and method will significantly improve the ease and safety of conduit insertion (such as the implantation of AAC devices, for example). For example, various embodiments of the present invention may allow the outer tube to be securely operably engaged with the tissue wall (due at least in part to the cooperation of the attaching device and the ring) prior to the removal of a tissue core to define an aperture in the tissue wall. Thus, portions of the system disclosed herein may define a guide aperture extending axially through the outer tube for receiving a coring device that may be configured to be capable of efficiently removing and retrieving a tissue core while substantially simultaneously operably engaging a inner tube in the guide aperture so as to establish fluid communication between first and second opposing surfaces of the tissue wall. As persons of ordinary skill in the art will readily appreciate, the various embodiments of the present invention may also be used in a minimally invasive, endoscopically assisted approach. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Having thus described various embodiments of the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  shows a non-limiting perspective view of an exemplary system for implanting a conduit device, according to one embodiment of the present invention; 
         FIG. 2  shows a non-limiting side cross-sectional view of an exemplary system for implanting a conduit device, according to one embodiment of the present invention; 
         FIG. 3  shows a non-limiting side cross-sectional view of an exemplary conduit device implanted in a tissue wall, according to one embodiment of the present invention; 
         FIG. 4  shows a non-limiting side view of an exemplary system for implanting a conduit device, according to one embodiment of the present invention; 
         FIGS. 5A-5G  show an exemplary set of views of the installation of a conduit device using an exemplary system, according to one embodiment of the present invention; 
         FIG. 5A  shows a non-limiting side cross-sectional view of an exemplary system for implanting a conduit device comprising an attaching device at least partially implanted in a tissue wall, according to one embodiment of the present invention; 
         FIG. 5B  shows a non-limiting side cross-sectional view of an exemplary system for implanting a conduit device comprising an attaching device and a ring cooperating to secure at least a portion of the tissue wall between the attaching device and the ring so as to operably engage said outer tube with the tissue wall, according to one embodiment of the present invention; 
         FIG. 5C  shows a non-limiting side cross-sectional view of an exemplary system for implanting a conduit device comprising a coring device carrying an inner tube configured for insertion into a guide aperture defined by the outer tube, wherein the coring device is advanced at least partially through the tissue wall so as to remove a tissue core thereof, according to one embodiment of the present invention; 
         FIG. 5D  shows a non-limiting side cross-sectional view of an exemplary system for implanting a conduit device comprising a coring device carrying an inner tube configured for insertion into a guide aperture defined by the outer tube, wherein the coring bore defined by the coring device contains a tissue core removed from the tissue wall, according to one embodiment of the present invention; 
         FIG. 5E  shows a non-limiting side cross-sectional view of an exemplary system for implanting a conduit device comprising a coring device carrying an inner tube configured for insertion into a guide aperture defined by the outer tube, wherein a piercing rod is retracted through the coring bore after removal of the tissue core such that the tissue core is retrievable via a proximal end of the coring device, according to one embodiment of the present invention; 
         FIG. 5F  shows a non-limiting side cross-sectional view of an exemplary system for implanting a conduit device, wherein the outer tube and inner tube are installed in the tissue wall so as to establish fluid communication between the first and second surfaces of the tissue wall, according to one embodiment of the present invention; 
         FIG. 5G  shows a non-limiting side cross-sectional view of an exemplary coring device, wherein a handle operably engaged with a proximal end of the coring device contains a tissue core removed from the tissue wall by the coring device, according to one embodiment of the present invention; 
         FIG. 6  shows a non-limiting side view of an exemplary coring device carrying an inner tube configured for insertion into a guide aperture defined by the outer tube, according to one embodiment of the present invention; and 
         FIG. 7  shows a non-limiting perspective view of an exemplary conduit device comprising an attaching device comprising a helical spring, according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements Like numbers refer to like elements throughout. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. 
     Although some embodiments of the invention described herein are directed to a conduit device  1  (see  FIGS. 1 and 7 , for example) and a system for implanting such a device to form an apicoaortic connector (AAC) between the cardiac apex and the aorta, it will be appreciated by one skilled in the art that the invention is not so limited. For example, aspects of the conduit device  1  and systems of the present invention can also be used to establish and/or maintain conduits in a variety of tissue structures using minimally-invasive and/or invasive delivery techniques. Furthermore, while the embodiments of the invention described herein are directed to the thoracoscopic implantation of the conduit device to form at least one port for establishing an AAC, it should be understood that the system and/or vascular conduit device embodiments of the present invention may be used to establish valved and/or open conduits (including bypass conduits) to augment native blood vessels in order to treat a variety of vascular conditions including, but not limited to: aortic valvular disease, congestive heart failure, left ventricle outflow tract obstructions (LVOTO), peripheral arterial obstructions, small vessel obstructions, and/or other conditions. Furthermore, the vascular conduit device and system of the present invention may also be used to establish a port for inter¬ventricular repairs such as, for example, valve repair and/or replacement or ablation procedures. Thus, the conduit device  1  described in further detail below may also comprise a threaded fluid-tight cap, and/or a cap having at least one pawl member (for engaging corresponding ridges defined on an outer surface of the conduit device  1 ) for selectively sealing a proximal end of the conduit device  1  such that the inner tube  40  thereof may serve as a re-usable port for repairing and/or treating diseased portions of the cardiac anatomy. Furthermore, the conduit device  1  and system embodiments of the present invention may also be used to implant a conduit and/or port for left ventricular assist devices. 
     It should be further understood that various embodiments of the conduit device  1  described herein may also be utilized to establish fluid communication between opposing surfaces of a variety of tissue walls and/or anatomical structures. For example, in some embodiments, the conduit device  1  and system for implanting described herein may be used to establish a conduit (and consequently fluid communication) between opposing surfaces of a wall of an anatomical structure that may include, but is not limited to: a urinary bladder; a gall bladder; a diaphragm; a thoracic cavity; an abdominal cavity; an intestinal structure; a cecal cavity; and other tissue wall structures. 
     It should be understood that the various conduit device  1  components described herein (see, for example, the components shown in  FIG. 1 ) may comprise a variety of biocompatible materials including, but not limited to: stainless steel; titanium substantially rigid biocompatible polymers; elastomeric biocompatible polymers; and combinations of such materials. For example, in some embodiments, the outer tube  10 , ring  30 , nut  20 , and inner tube  40  may comprise substantially rigid biocompatible polymers. In some embodiments, the attaching device  15  may comprise a biocompatible metal and/or metal alloy that may be embedded substantially within and/or operably engaged with an injection-molded polymer used to form the outer tube  10 . Furthermore, as described further herein, some embodiments of the present invention may further comprise a sealing member  35  operably engaged with a distal end of the ring  30 . In such embodiments, the sealing member  35  may comprise a substantially compliant biocompatible polymer (such as an elastomeric polymer) that may be suitable for establishing a substantially fluid tight seal between the ring  30  a surface of the tissue wall  850 . Similarly, the various components of the coring device  2  described herein may also comprise a combination of biocompatible materials suitable for removing and retaining the tissue core  850   a  in order to define an aperture in the tissue wall  850  such that the inner tube  40  may be installed to establish fluid communication between the opposing first and second surfaces  855 ,  853  of the tissue wall  850  (as shown in  FIG. 3 , for example). 
       FIG. 3  shows some exemplary components of a system for implanting a conduit device  1  in a tissue wall  850  having a first surface  855  and an opposing second surface  853 . As shown generally in  FIGS. 1 and 2 , such a system may comprise an outer tube  10  defining a guide aperture extending axially therethrough and an attaching device  15  extending from a distal end of the outer tube  10 . As shown in  FIG. 3 , for example, the attaching device  15  may be configured for advancing along a helical path at least partially through the tissue wall  850  such that at least a portion of the attaching device  15  becomes disposed substantially between the first surface  855  and the opposing second surface  853  of the tissue wall  850  when the outer tube  10  is rotated relative to the first surface  855  of the tissue wall  850 . As shown generally in  FIG. 2 , the attaching device  15  may be integrally formed within the outer tube  10 . For example, the attaching device  15  may, in some embodiments, be placed at least partially in a mold such that the polymeric or other components of the outer tube  10  may be molded substantially around at least a portion of the attaching device  15  (which may comprise a static coil and/or elastic spring, as described further herein). In other embodiments, the attaching device  15  may be operably engaged with at least a portion of the outer tube  10  via adhesive, RF welding, and/or other attachment methods that may be suitable for securely operably engaging the attaching device  15  to the outer tube  10 . 
     The attaching device  15  may comprise, in some embodiments, a helical static coil having a sharpened distal end adapted for piercing the tissue wall  850  as the outer tube  10  is rotated relative to the first surface  855  of the tissue wall  850 . In other embodiments, the attaching device  15  may comprise a helical elastic spring having a sharpened end adapted for piercing the tissue wall  850  as the outer tube  10  is rotated relative to the first surface  855  of the tissue wall  850 . In some embodiments, as shown in  FIG. 4 , wherein the attaching device  15  comprises a helical spring and/or coil, the spring and/or coil may device a radially-expanding helix as the attaching device  15  extends away from the distal end of the outer tube  10 . In some embodiments, wherein the attaching device comprises a conical and/or “radially-expanding” helix, the attaching device  15  may act to compress at least a portion of the tissue wall  850  radially inward and towards an outer surface of the inner tube  40  so as to establish a substantially fluid-tight seal between the outer surface of the inner tube  40  and the portion of the tissue wall  850  that has been urged radially inward. Furthermore, in some such embodiments, the radially-expanding helix of the attaching device  15  may correspond, for example, to a ring  30  comprising a frusto-conical assembly configured for receiving at least a portion of a substantially curved tissue wall  850  (see, for example,  FIG. 5B ) so as to form a substantially fluid-tight seal between the frusto-conical assembly of the ring  30  and the tissue wall  850 . 
     In other embodiments, as shown generally in  FIG. 7 , the attaching device  15  may comprise a helical spring and/or coil having a substantially constant helical diameter as the attaching device  15  extends away from the distal end of the outer tube  10 . The substantially consistent helical diameter of the attaching device  15  shown generally in  FIG. 7  may be useful for operably engaging the outer tube  10  with a substantially flat tissue wall  850 . Furthermore, as shown generally in  FIG. 7 , in some embodiments, the corresponding ring  30  (and the corresponding sealing member  35  that may be operably engaged therewith) may also be configured to provide a substantially flat and/or disc-ishaped sealing surface that may be suitable for seating on and/or establishing a substantially fluid-tight seal with a substantially flat first tissue surface  855  that may surround an aperture defined in a correspondingly flat tissue wall  850 . 
     As described herein, the system may further comprise a ring  30  operably engaged about an outer surface of the outer tube  10 . As shown generally in  FIGS. 3 and 5B , the ring  30  may be configured for cooperating with the attaching device  15  such that at least a portion of the tissue wall  850  is secured between the attaching device  15  and the ring  30  so as to operably engage the outer tube  10  with the tissue wall  850 . Some embodiments may further comprise a plurality of ridges  11  and/or threads disposed on the outer surface of the outer tube  10 . According to such embodiments, the ring  30  may comprise at least one deformable pawl member configured for releasably engaging the plurality of ridges  11  disposed on the outer surface of the outer tube  10 . Other embodiments (as shown generally in  FIG. 2 , for example), may also further comprise threading  11  on at least a portion of the outside surface of the outer tube  10  and corresponding threading on at least a portion of an inside surface of the ring  30 . The threading  11  (and corresponding threading on the inner surface of the ring  30 ) may be being configured to cooperate for axially securing the ring  30  relative to the outer tube  10 . As shown generally in  FIGS. 5A-5B , some embodiments may further comprise a nut  20  operably engaged about an outer surface of the outer tube  10  and proximal to the ring  30 . According to such embodiments, the nut  20  may comprise threading on at least a portion on an inside surface of the nut  20 . The threading disposed on the inside surface of the nut  20  may be configured for cooperating with the threading  11  on at least a portion of the outside surface of the outer tube  11  for axially securing the nut  20  relative to the outer tube  10  and the adjacent ring  20 . As shown in  FIGS. 5A-5B , the nut  20  may be configured for cooperating with the ring  30  to advance the ring  30  towards the distal end of the outer tube  10 . As shown generally in  FIGS. 5A-5B , the attaching device  15  may provide counter-traction so as to allow for the rotation (and resulting advancement) of the nut  20  (and the ring  30  disposed distally thereto) such that rotation of the nut  20  (and the corresponding movement of the ring  30  toward the first tissue surface  855 ) may draw at least a portion of the tissue wall  850  into engagement with an inner surface of the ring  30  such that the conduit device  1  (and particularly the outer tube  10  thereof) is stabilized, engaged in a substantially fluid tight seal, and/or operably engaged with respect to the tissue wall  850  prior to the use of a coring device  2  for removing a tissue core  850   a  via the guide aperture defined axially through the outer tube  10 . 
     In order to ensure that the ring  30  forms a substantially fluid-tight seal with the first surface  855  of the tissue wall  850  about the aperture defined therein, some embodiments (as shown in  FIG. 1 , for example) may further comprise a sealing member  35  operably engaged with a distal end of the ring  30 . The sealing member  35  may comprise, for example, a gasket or other elastomeric component configured for establishing a substantially fluid tight seal between the ring  30  and the first surface  855  of the tissue wall  855 . As described herein, some embodiments of the present invention may be configured for establishing fluid communication between the opposing sides of the walls of a mammalian heart (such as the ventricular apex, for example). In such embodiments, the conduit device  1  may be required to be operably engaged with a substantially curved tissue wall  850  (see  FIG. 5A , for example). In such embodiments, the ring  30  may comprise a frusto-conical assembly configured for receiving at least a portion of the substantially curved tissue wall  850  so as to form a substantially fluid-tight seal between the frusto-conical assembly of the ring  30  and the tissue wall  850 . As shown, for example, in  FIG. 5B , in some embodiments, the ring  30  may be urged towards a distal end of the outer tube  10  by the rotation of a nut  20  about threading  11  disposed on an outer surface of the outer tube  10 . Thus, according to some such embodiments, the cooperation of the attaching device  15  (which may comprise a piercing helical spring and/or coil, for example) with the ring  30  may act to draw at least a portion of the curved tissue wall  850  into the frusto-conical assembly of the ring  30  such that a substantially fluid-tight seal may be formed and maintained between the frusto-conical assembly of the ring  30  and the tissue wall  850 . In some conduit device  1  embodiments, as shown generally in  FIG. 2 , the ring  30  may comprise a seal testing aperture  36  that may allow a clinician to selectively test whether or not a substantially fluid-tight seal has been established between the ring  30  and the first surface  855  of the tissue wall  850  when the ring  30  is moved towards the distal end of the outer tube  10  and into engagement with the tissue wall  850 . For example, a clinician may operably engage a fluid source (such as a saline solution bag) with the seal testing aperture  36  (which may comprises a luer lock connector or other connector for operably engaging the fluid source) and introducing a fluid via seal testing aperture  36  and observing the interface between the ring  30  and the first surface  855  of the tissue wall  850  to see if any substantial amount of fluid emerges. If no fluid is readily visible, a clinician may be reasonably assured that the seal formed between the ring  30  and the tissue wall  850  is substantially fluid-tight. By assessing the seal formed between the ring  30  and the tissue wall  850 , a clinician may determine if it is medically safe to introduce the coring device  2  via the guide conduit defined in the outer tube  10  (i.e. determine if blood loss is likely to occur between the ring  30  and the first surface  855  of the tissue wall  850  when the coring device  2  (and the coring cylinder  65  thereof) is advanced through the tissue wall  850  as shown in  FIG. 5C ). 
     In some embodiments, the seal testing aperture  36  may also serve an alternative function for rotationally securing the ring  30  relative to and the first surface  855  of the tissue wall  850 . For example, a clinician may insert a needle and/or other elongate spike through the seal testing aperture  36  defined in the ring  30  and substantially into the tissue wall  850 . The interaction of the needle and/or spike with the ring  30  (via the seal testing aperture  36 ) and the tissue wall  850  may thus reduce a chance that the ring  30  (and the helical attaching device  15  extending from the outer tube  10 ) are rotatable relative to the tissue wall  850  such that the ring  30  and the helical attaching device  15  may be less prone to “backing out” of the tissue wall  850  once the seal is established between the ring  30  and the first surface  855  of the tissue wall  850 . 
     In some additional embodiments, as shown generally in  FIG. 7 , the ring  30  (and/or the sealing member  35  that may be operably engaged therewith) may define a substantially flat and/or disc-shaped annular sealing surface that may be configured for establishing a substantially fluid-tight seal between the ring  30  and a substantially flat first tissue surface  855  about an aperture defined in the tissue wall  850 . 
     Referring to  FIG. 5C , for example, some embodiments may further comprise an inner tube  40  defining a conduit aperture extending axially therethrough. The inner tube  40  may be configured for insertion into the guide aperture defined by the outer tube  10 . In some embodiments, as shown in  FIG. 6 , the inner tube  40  may be carried by a coring device  2  that may be advanced through the guide aperture defined by the outer tube  10  and configured for substantially simultaneously removing a tissue core  850   a  to define an aperture in the tissue wall  850  and operably engaging the inner tube  40  with the outer tube  10  so as to establish and/or maintain a reliable and engageable pathway for fluid communication between the first and second surfaces  855 ,  853  of the tissue wall  850 . In order to facilitate the secure engagement of the outer tube  10  with the inner tube  40 , some conduit device  1  embodiments may comprise a first securing device  13  operably engaged with a proximal end of the outer tube  10  and a complementary second securing device  43  operably engaged with a proximal end of the inner tube  40 . According to such embodiments, as shown generally in  FIG. 2 , the second securing device  43  may be configured for selectively operably engaging the first securing device  13  so as to operably engage the inner tube  40  with the outer tube  10 . As shown generally in  FIG. 6 , the second securing device  43  may comprise one or more deformable pawls configured for selectively operably engaging the first securing device  13  as shown in  FIG. 2  (wherein the first securing device  13  comprises one or more ridges disposed on a proximal portion of the outer surface of the outer tube  10 ). 
     As shown generally in  FIG. 6 , some system embodiments for installing a conduit device  1  may further comprise a coring device  2  configured for advancing through the conduit aperture defined by the inner tube  40  and through the tissue wall  850  to define an aperture therein by removing a tissue core  850   a  (see  FIG. 5D , for example, showing the coring device  2  removing a tissue core  850   a  and collecting the tissue core  850   a  in a coring bore defined by a coring cylinder  65 . As shown generally in  FIGS. 5C and 6 , the coring device  2  may be further configured for carrying the inner tube  40  through the aperture such that the inner tube  40  extends at least partially through the aperture (see  FIG. 5F , for example) so as to establish fluid communication between the first  855  and second  853  surfaces of the tissue wall  850 . In some embodiments, as shown in the cross-sectional side view of  FIG. 5D , the coring device  2  (and/or the coring cylinder  65  thereof) defines a coring bore extending axially therethrough configured for receiving the tissue core  850   a  removed by the coring cylinder  65 . 
     As shown in  FIGS. 5C-5E , the coring device  2  may also comprise a piercing rod  60  slidably advancable and retractable within the coring bore defined by the coring device  2 . The piercing rod  60  may further comprise a retrieval device  61  operably engaged with a distal end thereof and configured for axially retaining the tissue core  850   a  removed by the coring cylinder  65 . In various embodiments, the retrieval device  61  may include, but is not limited to: a barb; a hook; corkscrew; expandable balloon; a self-expanding structure; and/or other device configured for initially piercing the tissue wall  850  so as to be capable of retrieving the tissue core  850   a  removed by the coring device  2  as described further herein. As shown generally in  FIG. 5C , the piercing rod  60  may be configured for advancing so as to pierce the tissue wall  850  prior to removal of the tissue core  850   a  (i.e. prior to the advancement of the coring cylinder  65  through the tissue wall  850 ). Furthermore, as shown generally in  FIG. 5E , the piercing rod  60  may be further configured for retracting after removal of the tissue core  850   a  such that the tissue core  850   a  is retrievable via a proximal end of the coring device  2 . In some system embodiments for installing a conduit device  1 , the coring device  2  may further comprise a handle  63  operably engaged with a proximal end of the coring device  2  (and/or a proximal end of the coring cylinder  65 ). According to such embodiments, as shown generally in  FIG. 6 , the handle  63  may define a tissue core chamber  62  in communication with the coring bore defined by the coring cylinder  65 . As shown in  FIG. 5E , the tissue core chamber  62  may thus be configured for receiving the tissue core  850   a  retrieved by retraction of the piercing rod  60  (and the retrieval device  61  operably engaged with a distal end thereof). In order to allow a clinician to positively identify and/or confirm the removal and retraction of the tissue core  850   a , in some system embodiments at least a portion of the handle  63  may be provided with a substantially transparent material (such as a transparent polycarbonate polymer, for example) such that the tissue core  850   a  received by the tissue core chamber  62  may be visible (to a clinician or an endoscopic imaging device, for example) from a position substantially outside the handle  63 . 
       FIGS. 5A-5G  illustrate the various steps involved in the utilization of one embodiment of the system of the present invention for installing a conduit device  1  in a tissue wall  850  (such as the ventricular apex). It should be understood that various embodiments of the present invention may be utilized for installing the conduit device  1  for use in medical procedures that may include, but are not limited to: bypass; cardiac valve repair or replacement; attachment of a ventricular assist device; and combinations of such procedures. As shown in  FIG. 5A , an exemplary process for installing a conduit device  1  may begin with the implantation of the attaching device  15  in the tissue wall  850 . As described herein, the attaching device  15  may comprise a helical spring and/or coil configured for advancing along a helical path at least partially through the tissue wall  850  such that at least a portion of the attaching device  850  becomes disposed substantially between the first surface  855  and the opposing second surface  853  of the tissue wall  850  when the outer tube  10  is rotated relative to the first surface  855  of the tissue wall  850 . In some embodiments, the attaching device  15  may be sized such that the axial length of the attaching device  15  does not extend substantially distal to the second surface  853  of the tissue wall  850 . 
     In some embodiments, wherein the attaching device comprises a conical and/or “radially-expanding” helix, the attaching device  15  may act to compress at least a portion of the tissue wall  850  radially inward and towards an outer surface of the inner tube  40  so as to establish a substantially fluid-tight seal between the outer surface of the inner tube  40  and the portion of the tissue wall  850  that has been urged radially inward by the conical and/or radially-expanding helix of the attaching device  15 . Furthermore, in embodiments wherein the attaching device  15  comprises a conical and/or “radially-expanding” helix, the attaching device  15  may act to compress at least a portion of the tissue wall  850  radially inward such that the portion of the tissue wall  850  may be more readily received by ring  30  (which may comprise a frusto-conical structure configured for receiving the compressed portion of the tissue wall  850 ). As shown in  FIG. 5B , the conduit device  1  installation process may continue with the advancement and/or tightening of the ring  30  towards a distal end of the outer tube  10 . As described herein, some conduit device  1  embodiments of the present invention may comprise a nut  20  operably engaged about an outer surface of the outer tube  10  proximal to the ring  30 . In some such embodiments, the nut  20  may comprise threading on at least a portion on an inside surface thereof, wherein the threading is configured for cooperating with the threading  11  on at least a portion of the outside surface of the outer tube  10 . The nut  20  may thus be configured to cooperate with the ring  30  to advance the ring  30  towards the distal end of the outer tube  10 , and therefore into contact with the first surface  855  of the tissue wall  850 . As shown generally in  FIG. 5B , once the nut  20  and ring  30  are advanced distally (which may be accomplished by hand-tightening the nut  20 ), the ring  30  may cooperate with the attaching device  15  such that at least a portion of the tissue wall  850  is secured between the attaching device  15  and the ring  30  so as to securely operably engage the outer tube  10  with the tissue wall  850 . 
     As shown in  FIG. 5C , once the outer tube  10  is stabilized relative to the tissue wall  850 , a coring device  2  (which, in some embodiments, as shown in  FIG. 6 , may be configured for carrying an inner tube  40 ), may be inserted into the guide aperture defined axially within the outer tube  10 . As described herein with respect to  FIG. 6 , the coring device  2  may comprise a coring cylinder  65  configured for advancing through the conduit aperture defined by the inner tube  40  and through the tissue wall  850  to define an aperture therein by removing a tissue core  850   a  (see  FIG. 5D , for example). Referring again to  FIG. 5C , some embodiments may further comprise a piercing rod  60  slidably advancable and retractable within the coring bore defined by the coring cylinder  65 . The piercing rod  60  may comprise, in some embodiments, an elongate proximal end that may be manipulated (i.e. extended and/or retracted) by a clinician in order to initially pierce the tissue wall  850  and/or retract the tissue core  850   a  removed therefrom (as described further herein). As shown in  FIGS. 5D and 5E , the piercing rod  60  may further comprise a retrieval device  61  operably engaged with a distal end thereof and configured for axially retaining the tissue core  850   a  removed by the coring cylinder  65 . The piercing rod  60  may be configured for advancing so as to pierce the tissue wall  850  prior to removal of the tissue core  850   a  (i.e. prior to advancement of the coring cylinder  65 ). Furthermore, as shown in  FIG. 5E , the piercing rod  60  may be further configured for retracting after removal of the tissue core  850   a  such that the tissue core  850   a  is retrievable via a proximal end of the coring device  2 . 
     As shown in  FIGS. 5D and 6 , the coring device  2  may be further configured for carrying the inner tube  40  through the aperture such that the inner tube  40  extends at least partially through the aperture so as to establish fluid communication between the first and second surfaces  855 ,  853  of the tissue wall  850  (see also,  FIG. 3 , for example). As described herein, with respect to various conduit device  1  embodiments of the present invention the outer tube  10  may comprise a first securing device  13  operably engaged with a proximal end thereof and the inner tube  40  (carried, for example, by the coring device  2  into position relative to the outer tube  10 ) may comprise a complementary second securing device  43  operably engaged with a proximal end thereof. As shown generally in  FIG. 3 , the second securing device  43  (which may comprise a deformable pawl, for example) may be configured for selectively operably engaging the first securing device  13  (which may comprise a complementary at least one ridge disposed on an outer surface of the outer tube  10 ) so as to positively and securely operably engage the inner tube  40  with the outer tube  10 . 
     Referring again to  FIG. 5E , the coring device  2  may, in some embodiments, comprise a handle  63  operably engaged with a proximal end of the coring device  2 . As described herein, the handle  63  may define a tissue core chamber  62  in communication with the coring bore defined, for example, by the coring cylinder  65 . The tissue core chamber  62  may thus be configured for receiving the tissue core  850   a  retrieved by retraction of the piercing rod  60  (and the retrieval device  61  operably engaged with a distal end thereof). In some embodiments, the coring device  2  may also define a fill aperture configured for operably engaging a source of saline solution or other fluid that may be used to substantially flood the coring bore defined by the coring cylinder  65  and the tissue core chamber  62  so as to reduce the chance of introducing gas bubbles (i.e. air bubbles) into an interior chamber defined by the tissue wall  850  when the coring device  2  is introduced via the outer tube  10 . 
     As described generally herein with regard to the various system embodiments of the present invention, the conduit device  1  installation process may advantageously allow a clinician to visually confirm that the tissue core  850   a  removed by the coring cylinder  65  has been completely and cleanly removed from the aperture defined in the tissue wall  850 . For example, in some embodiments, at least a portion of the handle  63  may comprise a transparent material such that the tissue core  850   a  received within the tissue core chamber  62  may be directly visible by a clinician and/or an endoscopic imaging device from a position substantially outside the handle  63 . As shown in  FIGS. 5F and 5G , after the coring device  2  (and the tissue core  850   a  retained in the handle  63  thereof) is retracted and removed from the inner tube  40 , a clamp C may be applied to a proximal end of a graft portion that may be operably engaged with the inner tube  40  of the conduit device  1 . In other embodiments, the inner tube  40  may comprise one or more ridges defined on an outer surface of the proximal end thereof that may be configured for receiving a deformable cap or other cover for temporarily and/or semi-permanently closing the aperture defined by the installed conduit device  1 . As described herein, the conduit device  1  may be utilized as a portion of a two-part bypass system that may comprise another corresponding conduit device  1  installed in a tissue wall  850  defining a wall of the mammalian aorta, for example. The two corresponding conduit devices  1  may then be operably engaged with one another via a valve device so as to form an apicoaortic connection (AAC) in order to bypass, for example, a faulty valve or other mechanical defect present in a subject&#39;s cardiac anatomy. 
     Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.