Abstract:
A transseptal punch with a steering mechanism within the punch, such that punch can be steered and deflected within a guide catheter during delivery, to avoid skiving of the guide catheter inner wall by passage of the punch tip through the guide catheter. The punch can be advanced through a body lumen in its straight configuration and then be selectively articulated or curved to permit negotiation of tortuous curvature or to permit optimal approach or access to a puncture site. The punch is able to create holes in the atrial septum of the heart or other structures and is easier to use than punches that are pre-curved near their distal tip since it is easier to advance through accessory catheters.

Description:
[0001]    This application is a continuation of U.S. application Ser. No. 12/785,309, filed May 21, 2010, now U.S. Pat. No. 8,491,619, which is a continuation of U.S. application Ser. No. 11/492,328, filed Jul. 24, 2006, which in turn claims priority benefit under 35 USC §119(e) to U.S. Provisional Application No. 60/702,239, filed Jul. 25, 2005, entitled STEERABLE ENDOLUMINAL PUNCH, the entire contents of which are hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The invention relates to devices and methods for performing endovascular access to the cardiovascular system or other body vessels or body lumens, especially procedures performed in the fields of cardiology, radiology, electrophysiology, and surgery. 
       BACKGROUND OF THE INVENTION 
       [0003]    During certain interventional procedures that are directed at cardiac access, the patient is catheterized through an access point in a vein or artery. A catheter is routed to the heart or other region of the cardiovascular system through the access point, which may be created by a cutdown or a percutaneous access procedure. The catheter may be routed to a target location within the heart, cerebrovasculature, or other region of the cardiovascular system. In certain cases, it becomes necessary to create a hole in a cardiovascular structure so that catheters or devices can be routed through a wall so as to provide for placement on the other side of the wall. One such case is the need to punch a hole in the septum that divides the right atrium of the heart from the left atrium. Such atrial septal punctures are increasingly used to gain access to the left atrium by way of the central venous system and the right atrium. Access to the left atrium of the heart is often useful in therapeutic and diagnostic procedures such as, but not limited to, valve replacement, valve repair, electrophysiology mapping, cardiac ablation, atrial appendage plug placement, and the like. 
         [0004]    The currently accepted procedure for left atrial access involves routing a needle called a Brockenbrough™ needle into the right atrium with the Brockenbrough needle pre-placed within a guiding catheter. The guiding catheter specifically preferred for use with a Brockenbrough needle is called a Mullins™ catheter. The Brockenbrough needle is a long punch formed from a stainless steel wire stylet that is surrounded by a stainless steel tube. The distal end of the stainless steel tube forms a relatively sharp circular punch capable of penetrating certain vascular structures such as the inter-atrial septum. Brockenbrough needle stylets are typically 0.013 to 0.014 inches in diameter while the stainless steel tube is generally between 0.045 and 0.050 inches in outside diameter. The Brockenbrough needle outside diameter is configured to slidingly fit within the central lumen of the Mullins catheter. The stainless steel tube is substantially straight along most of its length but is pre-bent into a curved or “J” shape at its distal end. A loop at the proximal end of the Brockenbrough stylet facilitates grasping of the stylet and performing manual advance or retraction. The current art considers the access to the right atrium from the femoral vein to be relatively straight so the current devices are straight except for the distal curve, which is shaped for the approach to the atrial septal wall. 
         [0005]    The Brockenbrough needle, a relatively rigid structure, is operated by advancing the device, with its stylet wire advanced to blunt the sharp tip, within its guiding catheter through the inferior vena cava and into the superior vena cava. Under fluoroscopic guidance, the Brockenbrough needle, retracted inside the distal tip of the Mullins catheter, is withdrawn caudally into the right atrium until it falls or translates medially into the Fossa Ovalis. The force of the Brockenbrough needle/Mullins catheter assembly pushing against the relatively weak atrial septal wall causes the Fossa Ovalis to become tented toward the left atrium. The Brockenbrough needle, protected by the blunt distal tip of the Mullins catheter, is firmly held against the Fossa Ovalis of the atrial septum. Pressure monitoring and dye injection are carried out through the central lumen of the punch following removal of the stylet wire. The circular or hollow punch is next advanced distally to puncture a hole through the atrial septum. Erroneous placement of the punch can lead to penetration of adjacent structures such as the aorta, damage to which would cause potentially severe hemorrhage and potentially compromise the health of the patient. Thus, extreme care is exercised to verify location prior to the actual punching step. The Brockenbrough needle is next advanced through the atrial septum. The guide catheter, which includes a removable, tapered, distal dilator, having a central lumen for the Brockenbrough needle, is advanced over the Brockenbrough needle system and into the left atrium. The Brockenbrough needle is next removed from the Mullins guide catheter along with the central dilator or obturator. 
         [0006]    A main disadvantage of this system is that the Brockenbrough needle system is pre-curved at its distal end and is relatively rigid. This pre-curving, rigidity, and necessary distal sharpness causes the Brockenbrough needle system to carve material from the interior wall of the otherwise straight guiding catheter when the Brockenbrough needle assembly is inserted therethrough. The material carved from the guide catheter could potentially be released into the cardiovascular system and generate emboli with any number of serious clinical sequelae. Should this embolic catheter material enter the left atrium it could flow into and block important arterial vasculature such as the coronary arteries or cerebrovasculature. Furthermore, advancing a pre-curved, rigid punch through the cardiovascular system is difficult and could potentially damage the vessel wall or any number of significant cardiovascular structures, during the advancement. 
         [0007]    It would be desirable to have a Brockenbrough needle system that was initially straight and then became curved after being inserted into the guiding catheter. Such a straight Brockenbrough configuration would be advantageous during ex-vivo insertion as well as insertion after the guide catheter has already been placed into the cardiovascular system. During ex-vivo insertion, the debris can be flushed from the lumen of the guide catheter but complete removal is not assured and emboli can still be generated by the device. However, if the guide catheter was already inserted into the cardiovascular system, the debris could not be flushed out ahead of time and could easily flow toward or be released into the cardiovascular system with potentially catastrophic or fatal results. Furthermore, the needle or punch could be more easily advanced into the body lumen if it were not pre-curved. 
       SUMMARY OF THE INVENTIONS 
       [0008]    In an embodiment, the invention is a transvascularly or endovascularly placed tissue punch, with internal deflectability or the ability to articulate, at its distal end, in a direction away from its longitudinal axis. The punch can also be termed a catheter, needle, or cannula. The punch is generally fabricated from stainless steel and comprises an outer tube, an intermediate tube, a central stylet wire, and a distal articulating region. The deflecting or articulating mechanism is integral to the punch. The punch, needle, or catheter is sufficiently rigid, in an embodiment, that it can be used as an internal guidewire or internal guide catheter. The punch is useful for animals, including mammals and human patients and is routed through body lumens or other body structures to reach its target destination. 
         [0009]    In an embodiment, the punch comprises an inner core wire or stylet, an intermediate tube and an outer tube. In an embodiment, the stylet can be removable or non-removable. The punch further comprises a hub at its proximal end which permits grasping of the punch and also includes a stopcock or valve to serve as a lock for the stylet, or inner core wire, as well as a valve for control of fluid passage into and out from the innermost lumen within which the stylet or inner core wire resides. The proximal end further comprises one or more control handles to manipulate the amount of articulation at the distal end of the catheter. The proximal end further is terminated with a female Luer or Luer lock port, which is suitable for attachment of pressure monitoring lines, dye injection lines, vacuum lines, a combination thereof, or the like. 
         [0010]    The punch is fabricated so that it is substantially straight from its proximal end to its distal end. Manipulation of a control mechanism at the proximal end of the punch causes a distal region of the punch to bend or curve away from its longitudinal axis. The bending, steering, or articulating region is located near the distal end of the punch and can be a flexible region or structure placed under tension or compression by pull wires or control rods routed from the control handle at the proximal end of the punch to a point distal to the flexible region. In another embodiment, the bending or articulating mechanism can also be created by pre-bending the outer tube in one direction and bending the intermediate tube in another direction. The two tubes can be rotated relative to each other, about their longitudinal axis, by turning knobs or grips at the proximal end of the punch. When the curvatures of both tubes are aligned, the tubes will generally cooperate and not oppose each other, thus, maximum curvature or deflection is generated. When the tubes are rotated so their natural curvatures are aligned 180 degrees from each other, the curves will oppose each other or cancel out. Thus, the nested tubes will be substantially straight when the curvatures of the two concentric tubes oppose each other. Alignment marks or graduations at the proximal end can be used to assist with proper rotational alignment of the two tubes. The central core wire or stylet is generally straight and flexible and does not contribute to the curvature. In another embodiment, however, the stylet can be imparted with a curvature to assist with steering or articulation. Rotation of the two concentric tubes at relative angles between 180 degrees and 0 degrees will result in intermediate amounts of deflection so the amount of deflection can be increased or decreased in an analog, continuously variable, digital, or stepwise fashion. The stepwise or digital response can be generated using detents or interlocks that weakly engage at specific pre-determined locations. A locking mechanism can be further utilized to hold the two tubes in rotational alignment once the desired amount of curvature has been achieved. 
         [0011]    In another embodiment, steerability can be obtained using actuators on the surface or within the interior of the cannula to force bending of the cannula. These actuators can be typically electrically powered. In an embodiment, an actuator can comprise electrical leads, a power source, a compressible substrate, and shape memory materials such as nitinol. Such actuators may be distributed along the length of the cannula. The actuators may be placed so as to oppose each other. Opposing actuators are activated one at a time and not simultaneously and can generate a steering effect or back and forth motion. 
         [0012]    Other embodiments of the inventions comprise methods of use. One method of use involves inserting the central core wire so that it protrude out the distal end of the punch. A percutaneous or cutdown procedure is performed to gain access to the vasculature, either a vein or an artery. An introducer and guidewire are placed within the vasculature and the guidewire is routed proximate to the target treatment site. The introducer can be removed at this time. A guiding catheter, preferably with a central obturator or dilator is routed over the guidewire to the target site. In an embodiment, the target site can be the atrial septum. The guidewire can be removed at this time. The punch is adjusted so that it assumes a substantially straight configuration. The punch can be advanced through the central lumen of the already placed catheter. By making the punch as straight as possible, there is no curvature to force the sharpened distal edges of the punch to scrape the inside of the catheter lumen as the punch is advanced distally inside the guide catheter and potentially dislodge or scythe away debris or material which could cause embolic effects to the patient. Carefully ensuring that the punch does not protrude beyond the distal end of the catheter or its obturator, the punch is next deflected so that it forms a curve. The curve is oriented so that it is medially directed toward the atrial septum. Alignment with any curvature of the catheter can be completed at this time. The punch and guide catheter/obturator are withdrawn caudally, as a unit, into the right atrium. The punch and guide catheter are positioned using fluoroscopy or other imaging system against the Fossa Ovalis. The Fossa Ovalis is a relatively thin structure and the force of the punch will tent the Fossa Ovalis toward the left atrium. In one embodiment, the central core wire or stylet, initially advanced, can next be withdrawn to expose the sharp distal edge of the punch. When correctly positioned under fluoroscopy, ultrasound, or other imaging system, dye can be injected into the central lumen of the punch at its proximal end and be expelled out of the distal end of the punch and obturator to paint or mark the Fossa Ovalis. A generally “V-shaped” mark can be observed under fluoroscopy, which denotes the location of the Fossa Ovalis. The curvature of the punch can be increased or decreased by articulation to gain optimal alignment with the Fossa Ovalis. This steering function can be very beneficial in device placement. 
         [0013]    Maintaining the position of the guiding catheter against the Fossa Ovalis, the punch is advanced distally against and through the atrial septum, in the region of the Fossa Ovalis, so that it penetrates and protrudes into the left atrium. In order to stabilize the atrial septal tissue prior to coring, a distally protruding corkscrew tipped wire or a vacuum head operably connected to the proximal end of the punch, can be used to grasp and retract the septal tissue. Once the initial penetration is completed, the guide catheter is next advanced, with its tapered obturator leading the way, across the atrial septum until it resides within the left atrium. The tapered obturator or dilator along with the punch can be removed at this time to allow for catheter placement through the guiding catheter. In another embodiment, a calibrated spacer can be used between the guide catheter hub and the punch hub to ensure that the punch does not protrude beyond the distal end of the guide catheter tip until the desired time for punching the hole. At this point, the spacer is unlocked and removed from the punch or catheter. 
         [0014]    In another embodiment, the core wire or stylet is sharpened and serves as a tissue punch. In this embodiment, the distal end of the hollow tubes of the punch are blunted and made relatively atraumatic. Once the core wire punch has completed tissue penetration, the outer tubes are advanced over the central punch wire through the penetration and into the left atrium. In another embodiment, a pressure monitoring device such as a catheter tip pressure transducer, or a pressure line terminated by a pressure transducer, can be affixed to a quick connect, generally a Luer fitting, at the proximal end of the punch hub. By monitoring pressure, it is possible to determine when the distal end of the punch has passed from, for example, the right atrium into the left atrium, because the pressure versus time curves in these two chambers are measurably, or visually, different. The proximal end of the hub further has provision for attachment to a dye injection line for use in injecting radiographic contrast media through the central lumen of the punch. Typically a manifold can be attached to the Luer fitting on the proximal end of the hub, the manifold allowing for pressure monitoring, for example on a straight through port, and for radiopaque dye injection, for example through a side port. A stopcock, or other valve, can be used to control which port is operably connected to the central lumen of the punch. 
         [0015]    For purposes of summarizing the invention, certain aspects, advantages and novel features of the invention are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. These and other objects and advantages of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    A general architecture that implements the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. Throughout the drawings, reference numbers are re-used to indicate correspondence between referenced elements. 
           [0017]      FIG. 1  illustrates a side view of a trans-septal punch assembled so that the intermediate tube is bent in a direction 180 degrees opposite that of the outer tube, resulting in a substantially straight punch configuration; 
           [0018]      FIG. 2  illustrates a side view of the disassembled trans-septal punch showing the central core wire or stylet, the intermediate tube bent in one direction and the outer tube bent in another direction; 
           [0019]      FIG. 3  illustrates a side view of the trans-septal punch assembled so that the intermediate tube bend is aligned in the same direction as the outer tube bend, resulting in a curved distal end on the punch assembly; 
           [0020]      FIG. 4  illustrates a side view of a trans-septal punch comprising a flexible region proximal to the distal end and pull-wires disposed between the distal end and the proximal end of the punch; 
           [0021]      FIG. 5  illustrates a side view of the trans-septal punch of  FIG. 4  wherein one of the pull-wires is placed in tension causing the distal flexible region of the punch to deflect into an arc away from the longitudinal axis of the punch; 
           [0022]      FIG. 6  illustrates an adjustable, spacer, which sets and maintains the distance between the distal end of the punch hub and the proximal end of a guide catheter hub. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    In accordance with current terminology pertaining to medical devices, the proximal direction will be that direction on the device that is furthest from the patient and closest to the user, while the distal direction is that direction closest to the patient and furthest from the user. These directions are applied along the longitudinal axis of the device, which is generally an axially elongate structure having one or more lumens or channels extending through the proximal end to the distal end and running substantially the entire length of the device. 
         [0024]      FIG. 1  illustrates a side view of a punch, needle, or catheter assembly  100 , with an integral articulating or bending mechanism. The punch assembly  100  comprises a stylet or obturator wire  102 , an intermediate tube  104 , an outer tube  106 , an obturator grasping tab  108 , a stopcock  110 , an intermediate tube pointer  112 , an outer tube pointer  114 , an intermediate tube hub  116 , and an outer tube hub  118 . 
         [0025]    Referring to  FIG. 1 , the obturator wire  102  is affixed to the obturator grasping tab  108 . The stylet or obturator wire  102  is inserted through the central lumen of the intermediate tube  104  and is slidably disposed therein. The stopcock  110  is affixed to the intermediate tube hub  116  and the through lumen of the stopcock  110  is operably connected to the central lumen of the intermediate tube  104 . The intermediate tube pointer  112  is affixed to the intermediate tube hub so that it is visible to the user. The outer tube pointer  114  is affixed to the outer tube hub  118  so that it is visible to the user. The intermediate tube hub  116  and the intermediate tube  104  are able to rotate about the longitudinal axis within the outer tube hub  118  and the outer tube  106 . In an embodiment, the intermediate tube  104  is restrained from longitudinal motion relative to the outer tube  106 . In another embodiment, the intermediate tube  104  can be advanced distally relative to the outer tube  106 . In this latter embodiment, advancement of the inner tube  104  can be used to facilitate punching. The distal end of the intermediate tube  104  can be sharpened and serve as a punch. The distal end of the intermediate tube  104  is sheathed inside the outer tube  106  to protect the tissue from the sharp distal edge of the intermediate tube  104  until the intermediate tube  104  is advanced distally outside the distal end of the outer tube  106 . A releaseable lock can be used to maintain the axial or longitudinal position of the intermediate tube  104  relative to the outer tube  106  until punching is required. A releaseable lock can further be used to maintain the rotational position of the intermediate tube hub  116  and thus the intermediate tube  104  relative to the outer tube hub  118  and the outer tube  106 . 
         [0026]    All components of the punch assembly  100  can be fabricated from metals such as, but not limited to, stainless steel, Elgiloy™, cobalt nickel alloy, titanium, nitinol, or the like. The nitinol can be shape-memory or it can be superelastic. The metals used in the obturator wire  102 , the intermediate tube  104  and the outer tube  106  are advantageously cold rolled, heat treated, or otherwise processed to provide a full spring hardness. The intermediate tube  104 , the outer tube  106 , or both, are relatively rigid, resilient structures. Polymeric materials, such as, but not limited to, polycarbonate, ABS, PVC, polysulfone, PET, polyamide, polyimide, and the like, can also be used to fabricate the stopcock  110 , the intermediate tube hub  116 , the outer tube hub  118 , the intermediate tube pointer  112 , and the outer tube pointer  114 . The materials are beneficially radiopaque to maximize visibility under fluoroscopy during the procedure. Additional radiopaque markers fabricated from tantalum, platinum, iridium, barium sulfate, and the like can be added to improve visibility if needed. The intermediate tube  104  is curved or bent near its distal end into a gentle curve, preferably with a radius of between 1 to 5 inches and so that the distal tip is deflected through an angle of approximately 10 to 90 degrees from the longitudinal axis of the intermediate tube  104 . The outer tube  106  is curved or bent near its distal end into a gentle curve, preferably with a radius of between 1 to 5 inches and so that the distal tip is deflected through an angle of approximately 10 to 90 degrees from the longitudinal axis of the outer tube  106 . The intermediate tube hub  116  is welded, silver soldered, bonded, crimped, or otherwise fastened to the proximal end of the intermediate tube  104  so that the intermediate tube pointer  112  points in the direction of the bend in the intermediate tube  104 . The outer tube hub  118  is welded, silver soldered, bonded, crimped, or otherwise fastened to the proximal end of the outer tube  106  so that the outer tube pointer  114  points in the direction of the bend in the outer tube  106 . When the intermediate tube pointer  112  is oriented 180 degrees away from the direction of the outer tube pointer  114 , the bend in the intermediate tube  104  substantially counteracts or opposes the bend of the outer tube  106  and the coaxial assembly  100  is substantially straight, as shown in  FIG. 1 . The stopcock  110  can also be a ring seal, Tuohy-Borst valve, membrane valve, hemostasis valve, gate valve, or other valve, generally, but not necessarily manually operated. The stiffness of the intermediate tube  104  and the outer tube  106  are sufficient that the punch can be used as a guide for other catheters through which the punch  100  is passed. 
         [0027]      FIG. 2  illustrates a side view of a stylet or obturator  140  further comprising the obturator wire  102  and the obturator-grasping tab  108 . The obturator wire  102  is blunted at its distal end to render it as atraumatic as possible. In another embodiment, the obturator wire  102  can be tapered in diameter to render it very flexible and therefore atraumatic at its distal end. The obturator wire  102 , in another embodiment, can be sharpened and serve as a needle or primary punching mechanism.  FIG. 2  also illustrates an intermediate punch assembly  120  further comprising the intermediate tube  104 , the stopcock  110 , the intermediate tube pointer  112 , the intermediate tube hub  116 , an intermediate tube seal  124 , an intermediate tube pointer ball  126 , a through lumen port  128 , a beveled distal tip  132 , and a pre-set curve  136 .  FIG. 2  further illustrates an outer tube assembly  122  further comprising the outer tube  106 , the outer tube hub  118 , the outer tube pointer  114 , an outer tube distal curve  130 , and an outer tube pointer ball  134 . 
         [0028]    Referring to  FIG. 2 , the obturator-grasping tab  108  is affixed, either integral to, silver soldered, welded, crimped, adhered, pinned, or otherwise attached, to the proximal end of the obturator wire  102 . The intermediate tube  104  is affixed to the intermediate tube hub  116  by silver soldering, welding, potting, crimping, setscrew, pin, or other fixation method, such that the hub  116  rotates 1 to 1 with the intermediate tube  104 . An optional intermediate tube pointer ball  126  is affixed to the intermediate tube pointer  112  and provides additional visual and tactile rotational positioning sense for the intermediate punch or needle assembly  120 . A curve or bend  136  is heat set, or cold worked into the intermediate tube  104  at or near its distal end. The distal end of the intermediate tube  104  comprises a bevel  132  which helps serve as a punch or cutting edge for the intermediate tube  104 . The angle of the bevel  132  can range between 20 and 70 degrees from the direction perpendicular to the longitudinal axis of the intermediate tube  104 . In another embodiment, the bevel is removed and the distal tip of the intermediate tube  104  is a gentle inward taper or fairing moving distally that serves as a dilator should the obturator wire  102  be used as the punching device rather than the blunt distal tip obturator of the intermediate tube  104 . The intermediate tube hub  116  further comprises a circumferential groove with an “O” ring  124  affixed thereto. The “O” ring  124  serves to form a fluid (e.g. air, blood, water) tight seal with the inner diameter of the outer sheath hub  118  central lumen and allows for circumferential rotation of the intermediate tube hub  116  within the outer tube hub  118 . The “O” ring  124  is fabricated from rubber, silicone elastomer, thermoplastic elastomer, polyurethane, or the like and may be lubricated with silicone oil or similar materials. The stopcock  110  can be a single way or a three-way stopcock without or with a sideport, respectively. 
         [0029]    The outer punch assembly  122  comprises the bend  130 , which is heat set or cold worked into the outer tube  106  in the same longitudinal location as the bend  136  of the intermediate tube. The wall thicknesses of the intermediate tubing  104  and the outer tubing  106  are chosen to provide bending forces that cancel out when the curves  136  and  130  are oriented in opposite directions and the intermediate tubing  104  is inserted fully into the outer tubing  106 . The wall thickness of the outer tube  106  and the intermediate tube  104  can range between 0.003 inches and 0.20 inches, preferably ranging between 0.004 and 0.010 inches. The outer diameter of the outer tube  106  can range between 0.014 and 0.060 inches and preferably between 0.025 and 0.050 inches. The outer diameter of the obturator wire  102  can range between 0.005 and 0.030 inches and preferably range between 0.010 and 0.020 inches. 
         [0030]      FIG. 3  illustrates a side view of the punch assembly  100  fully assembled and aligned so that both the intermediate tube distal curve  136  (Refer to  FIG. 2 ) and the outer tube distal curve  130  are aligned in the same direction resulting in a natural bend out of the axis of the punch  100 . The punch assembly  100  comprises the obturator wire  102 , the intermediate tube  104 , the outer tube  106 , the obturator grasping tab  108 , the stopcock  110 , the intermediate tube pointer  112 , the outer tube pointer  114 , the intermediate tube hub  116 , the intermediate tube pointer ball  126 , and the outer tube pointer ball  134 . 
         [0031]    Referring to  FIG. 3 , the outer tube pointer  114  and intermediate tube pointer  112  are aligned together and in this configuration, the tubing assembly possesses its maximum curvature, which is oriented in the same directions as the pointers  112  and  114 . The pointer balls  126  and  134  are aligned together to provide additional tactile and visual indices of curvature direction. In an embodiment, the curvature of the tube assembly  104  and  106  is unbiased with no net force exerted therebetween and an angle of approximately 45 degrees is subtended by the device in the illustrated configuration. Further curvature can also occur out of the plane of the page so that the curvature takes on a 3-dimensional shape, somewhat similar to a corkscrew. In another embodiment, the curvature of the aligned inner tube  104  and the outer tube  106  subtends an angle of 90-degrees or greater. Again, the intermediate tube  104  and the outer tube  106  have stiffness sufficient that the assembly is capable of guiding any catheter through which the punch  100  is passed. In another embodiment, the intermediate tube  104  and the outer tube  106  have different degrees of curvature so that when they are aligned, a net force still is generated between the two tubes, although a maximum curvature configuration is still generated. This embodiment can be advantageous in permitting articulation in a direction away from the direction of primary curvature. The radius of curvature of the punch  100  can range from substantially infinity, when straight, to as little as 0.5-cm, with a preferred range of infinity to as little as 2-cm radius when fully curved or articulated. One embodiment permits a substantially infinite to a 3-cm radius of curvature. The overall working length of the punch, that length from the proximal end of the outer tube hub to the distal most end of the punch, can range from 10 to 150-cm and preferably between 60 and 100-cm, with a most preferred range of between 70 and 90-cm. A preferred curve has a radius of about 3-cm and is bent into an arc of about 45 to 90 degrees. 
         [0032]      FIG. 4  illustrates a side view of another embodiment of a needle or punch assembly  400  comprising an obturator wire  102 , an obturator wire grasping tab  108 , a stopcock  110 , an intermediate tube  404 , an outer tube  406 , a plurality of deflecting wires  412 , an outer tube hub  414 , a deflecting lever  416 , a weld  420 , an axis cylinder  424 , a plurality of deflecting wire channels  426 , and a flexible region  430 . The distal end of the region just proximal to the flexible region  430  is shown in breakaway view. Furthermore, the distal end of the region just proximal to the flexible region  430  as well as the flexible region  430  has been expanded in scale so that certain details are more clearly visible. 
         [0033]    Referring to  FIG. 4 , the flexible region  430  is affixed to the outer tube  406  by a weld  420 . The flexible region  430  can also be fixed to the outer tube  406  by a crimp, pin, setscrew, adhesive bond, interference fit, mechanical interlock, thread, or the like. The attachment between the flexible region  430  and the outer tube  406  is made at the proximal end of the flexible region  430  and a second attachment or weld  420  can be made at the distal end of the flexible region  430  so as to attach to a length of distal outer tube  406 . The flexible region  430  can comprise a length of coiled wire such as that used in guidewires, it can be a tube that comprises cutouts to provide a backbone configuration to impart flexibility, it can be a length of polymeric tube with elastomeric characteristics, or it can be another type of structure that is known in the art as providing flexibility. These preferred structures also advantageously provide column strength and kink resistance to the flexible region  430 . The center of the flexible region  430  is hollow and comprises a lumen, which is operably connected to the central lumen of the outer tube  406  at both the proximal and distal end of the flexible region  430 . The stopcock  110  is affixed, at its distal end, to the outer tube hub  414 . The outer tube hub  414  further comprises a deflecting lever  416  that is affixed to the axis cylinder  424 , which serves as an axle or rotational pin, and can be moved proximally or distally by manual action on the part of the operator or by a motor or other electromechanical actuator (not shown). The deflecting lever  416  is operably connected to the proximal ends of the deflecting wires  412 . In an exemplary embodiment, one of the deflecting wires  412  is affixed to the top of the axis cylinder  424  and the other deflecting wire is affixed to the bottom of the axis cylinder  424 . When the deflecting lever is pulled proximally, for example, the top wire  412  is placed under tension and the tension on the bottom wire is relieved causing tension to be exerted on the distal end of the punch  400 . The deflecting wires  412  are slidably routed through the deflecting wire channels  420  within the outer tube  406 . The deflecting wires  412  also run through the deflecting wire channels  420  within the flexible region  430 . The deflecting wires  412  can also be routed through the internal lumen of the outer tube  406  and the flexible region  430 . 
         [0034]    Referring to  FIG. 4 , the outer tube hub  414  is affixed to the proximal end of the outer tube  406  by a crimp, pin, setscrew, adhesive bond, interference fit, mechanical interlock, thread, or the like. The intermediate tube  404  is affixed to the distal end of the outer tube  406  by a crimp, pin, setscrew, adhesive bond, interference fit, mechanical interlock, thread, or the like. In another embodiment, the intermediate tube  404  is routed throughout the length of the outer tube  406 . In this embodiment, the intermediate tube can comprise grooves (not shown) that serve as deflecting wire channels  420  when the intermediate tube  404  is inserted inside the outer tube  406 . Such grooves can also be disposed on the interior surface of the outer tube  406 , rather than on the exterior surface of the inner tube  404 . The obturator wire  102  and the attached grasping loop  108  are slidably disposed within the inner lumen of the outer tube  406 , or the intermediate tube  404 . The intermediate tube  404  is gently tapered up to the outer tube  406  at the distal end of the outer tube  406  in a transition region so that a dilator effect can be created during distal advancement of the punch  400 . The distal end of the intermediate tube  404  can comprise a bevel  132  ( FIG. 2 ) or other sharp point for punching through biological tissue. The distal end of the intermediate tube  404  preferably forms a non-coring needle or punch that does not excise a tissue sample. The non-coring punch feature is achieved by keeping the central lumen closed or very small. The non-coring punch  400  embodiment can comprise filling the lumen of the intermediate tube  404  with the obturator or stylet wire  102  to prevent the sharp edge of the intermediate tube from functioning as a trephine. 
         [0035]      FIG. 5  illustrates a side view of the punch assembly  400  wherein the deflecting lever  416  has been withdrawn proximally causing increased tension in one of the deflecting wires  412 , causing the flexible region  430  to bend  422  out of the longitudinal axis. The punch assembly  400  further comprises the obturator wire  102 , the obturator wire grasping tab  108 , the stopcock  110 , the deflecting lever  416 , an axis cylinder  424 , the hub  414 , the outer tubing  406 , the intermediate tubing  404 , and the bend  422 . 
         [0036]    Referring to  FIG. 5 , the deflecting lever  416  has been moved proximally and the axis cylinder  424  causing the top deflecting wire  412  to be placed in tension while the bottom deflecting wire  412  is relaxed. The deflecting wires  412  are affixed at their distal end to the outer tubing  406  or the intermediate tubing  404  at a point substantially at or beyond the distal end of the flexible region  420 . The distal fixation point (not shown) of the deflecting wires  412  is off-center from the axis of the outer tubing  406  or intermediate tubing  404 . When uneven tension is created in the opposing deflecting wires  412 , the uneven tension on the distal end of the punch  400  causes the bendable region  430  to undergo deflection into a curve or bend  422 . Similarly, forward movement of the deflecting lever  416  will place the bottom deflecting wire  412  in tension while the upper deflecting wire  412  will be relaxed, causing the punch  400  to undergo a bend in the opposite direction (downward). The deflecting lever  416  can further comprise a ratchet and lock, a friction lock, a spring-loaded return, or other features to hold position or cause the lever and the bendable region  430  to return to a neutral deflection configuration (substantially straight). The spring nature of the outer tube  406  and the bendable region  430  can advantageously be used to cause a return to neutral once the deflection force is removed from the deflecting lever  416 . The stylet or obturator wire  102  can be withdrawn or extended to expose or protect (respectively) the distal end of the intermediate tube  404  which can be sharpened or blunted. The obturator wire  102  can further be used as the primary punch, especially if the distal tip of the obturator wire  102  is sharpened. If the obturator wire  102  is used as the primary punch, the proximal end of the intermediate tube hub is fitted with a Tuohy-Borst or other hemostatic valve to permit the obturator wire  102  to remain in place. In this embodiment, sidearms affixed proximal to the proximal end of the punch, and operably connected to the central lumen, serve to permit pressure monitoring and dye contrast injection without compromising hemostasis or air entry into the punch assembly  400 . 
         [0037]      FIG. 6  illustrates a side view of an adjustable spacer  600  interconnecting a guide catheter  620  and a punch assembly  100 . The spacer  600  further comprises a proximal connector  602 , a rotating nut  604 , an inner telescoping tube  608 , a threaded region  606 , a distal locking connector  610 , and an outer telescoping tube  614 . The guide catheter further comprises a tube  622 , a hub  624 , and a proximal connector  626 . The punch assembly  100  further comprises the stopcock  110 , the distal rotating locking connector  612 , the intermediate tube pointer  112 , the outer tube pointer  114 , and the intermediate tube hub  116 . The spacer  600  can comprise an optional slot  630 . 
         [0038]    Referring to  FIG. 6 , the punch assembly  100  is inserted through the central lumen of the adjustable spacer  600 . The distal end of the punch assembly  100  is then inserted through the central lumen of the guide catheter  620 . The hub  624  of the guide catheter  620  is affixed to the proximal end of the guide catheter tube  622 . The distal end of the hub  624  comprises a female Luer lock connection, which is bonded to, or integrally affixed to the hub  624 . The hub  624  can further comprise a seal or hemostasis valve such as a Tuohy-Borst fitting. The punch  100  hub  116  is terminated at its distal end by a swivel male Luer lock connector  612 . The adjustable spacer  600  comprises an outer telescoping tube  614 , shown in partial cutaway view that is terminated at its proximal end with a female Luer lock  602 . The proximal end of the outer telescoping tube  614  has a flange that permits rotational attachment of the rotating nut  604 , shown in partial cutaway view, so that the rotating nut is constrained in position, longitudinally, relative to the outer telescoping tube  614  but is free to rotate. The inner telescoping tube  608  is affixed at its distal end with a swivel male Luer connector  610 , or equivalent. The proximal end of the inner telescoping tube  608  is affixed to, or comprises, the integral threaded region  606 . The threaded region  606  mates with the internal threads on the rotating nut  604 . As the rotating nut  604  is rotated, either manually or by an electromechanical device, it moves forward or backward on the inner telescoping tube  608  and threaded region  606  thus changing the space between the hub  116  of the punch  100  and the proximal end of the hub  624  of the guide catheter  620 . The system is preferably set for spacing that pre-sets the amount of needle or stylet travel. In an embodiment, the rotating nut  604  comprises a quick release that allows disengagement of the inner telescoping tube  608  from the outer telescoping tube  614  so that collapse is permitted facilitating the tissue punching procedure of advancing the punch  100  distally relative to the hub  624 . The system further comprises hemostatic valves at some, or all, external connections to prevent air leaks into the punch  100 . The telescoping tube  608  can be set to disengage from the outer telescoping tube  614  to allow for longitudinal collapse so that the punch  100  can be advanced distally to provide its tissue punching function. In another embodiment, the spacer  600  comprises the slot  630  that permits the spacer to be removed sideways off the punch  100 . The slot  630  is wide enough to allow the outer tube  106  to fit through the slot  630  so the spacer  600  can be pulled off, or removed from, the punch  100  prior to the punching operation. Thus, the slot  630  can be about 0.048 to 0.060 inches wide and extend the full length of the spacer  600 . With the slot  630 , the spacer  600  comprises a generally “C-shaped” lateral cross-section. The spacer  600  can further comprise a slot closure device (not shown) to prevent inadvertent removal of the punch  100 . 
         [0039]    In another embodiment, the threaded region  606  and the rotating nut  604  are replaced by a friction lock on telescoping tubes, a ratchet lock, or other suitable distance locking mechanism. In yet another embodiment, a scale or series of markings (not shown) is incorporated into the adjustable spacer  600  to display the exact distance between the proximal end and the distal end of the spacer  600 . In another embodiment, the proximal end and the distal end of the spacer  600  do not comprise one or both of the female Luer lock  602  or the rotating male Luer lock  610 . In this embodiment, the spacer  600  provides positional spacing but does not affix the punch  100  to the guide catheter  620  so that the two devices move longitudinally as a unit. In another embodiment, the pull wires  412  of  FIG. 4 , which are strong in tension but cannot support compression are replaced by one or more control rods, which are flexible but which have column strength. Thus, deflection can be generated by imparting either tension on the control rod or compression and such tension and compression is capable of deflecting the distal tip of the punch  400  without the need of a separate control rod to impart tension in the other direction. The intermediate tube hub  116  is terminated at its proximal end by a female Luer, Luer lock, threaded adapter, bayonet mount, or other quick release connector. The quick connect or female Luer can be releasably affixed to a hemostasis valve, other stopcock, pressure transducer system, “Y” or “T” connector for pressure and radiopaque contrast media infusion, or the like. 
         [0040]    In another embodiment, a vacuum line can be connected to a port affixed to the proximal end of the punch. The port can be operably connected to a bell, cone, or other structure at he distal end of the punch by way of a lumen, such as the central lumen of the intermediate tube or an annulus between the intermediate and outer tube, within the punch. By application of a vacuum at the proximal end of the punch, the distal structure can be releasably secured to the atrial septum prior to punching through. In another embodiment, a corkscrew structure projects out the distal end of the punch and is operably connected to a knob or control at the proximal end of the punch by way of a control rod slidably or rotationally free to move within a lumen of the punch. The corkscrew structure can be screwed into tissue to releasably secure the distal end of the punch to the tissue, for example, to enhance stability of the punch prior to, during, or after the punching operation. 
         [0041]    Referring to  FIG. 1 , in another embodiment, the intermediate tube  104 , the outer tube  106 , or both, are fabricated from shape memory nitinol. In this embodiment, electrical energy can be applied to the pre-bent regions of the inner tube  104 , the outer tube  106 , or both. Upon application of electrical energy, Ohmic or resistive heating occurs causing temperature of the tubes to increase. The nitinol changes its state from martensitic to austenitic, with the increase in temperature, and can assume a pre-determined configuration or stress state, which is in this case curved. The austenite finish temperature for such a configuration is approximately 40 degrees centigrade or just above body temperature. In yet another embodiment, the austenitic finish temperature can be adjusted to be approximately 28 to 32 degrees centigrade. The punch  100  can be maintained at room temperature where it is substantially martensitic and non-rigid. Upon exposure to body temperatures when it is inserted into the core lumen of the guide catheter, it will assume its austenitic shape since body temperature is around 37 degrees centigrade. This can cause the punch  100  to curve from substantially straight to substantially curved. In this configuration, only a single tube, either the intermediate tube  104  or the outer tube  106  is necessary, but both tubes, while potentially beneficial, are not required. 
         [0042]    The punch can be used to create holes in various structures in the body. It is primarily configured to serve as an articulating or variable deflection Brockenbrough needle. However, the steerable punch can be used for applications such as transluminal vessel anastomosis, biopsy retrieval, or creation of holes in hollow organs or lumen walls. The punch can be used in the cardiovascular system, the pulmonary system, the gastrointestinal system, or any other system comprising tubular lumens, where minimally invasive access is beneficial. The punch can be configured to be coring or non-coring in operation, depending on the shape of the distal end and whether an obturator or the circular hollow end of the punch is used to perform the punching operation. In the coring configuration, a plug of tissue is removed, while in the non-coring configuration, substantially no tissue is removed from the patient. The punch facilitates completion of transseptal procedures, simplifies routing of the catheters, minimizes the chance of embolic debris being dislodged into the patient, and improves the ability of the cardiologist to orient the punch for completion of the procedure. The punch of the present invention is integral and steerable. It is configured to be used with other catheters that may or may not be steerable, but the punch disclosed herein does not require external steerable catheters or catheters with steerability to be steerable as it is steerable or articulating on its own. The punch is capable of bending and unbending a practically unlimited number of times. The punch is especially useful with catheters that are not steerable since the punch comprises its own steering system. 
         [0043]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. For example, the deflecting wires  412  can be replaced by an electromechanical actuator and external control unit. The scope of the invention is therefore indicated by the appended claims rather than the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.