CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This patent application claims priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Applications 60/757,443, filed Jan. 9, 2006, and 60/760,511, filed Jan. 21, 2006, and as a continuation-in-part under  35  U.S.C. § 120 of co-pending U.S. patent applications Ser. Nos. 11/090,574 and 11/090,588, filed Mar. 24, 2005, the contents of which provisional and non-provisional applications are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates in general to the field of medical devices and, in particular, to devices for use in interventional and diagnostic access, manipulation within, and negotiation of, the vascular system.  
       BACKGROUND OF THE INVENTION  
       [0003]     The vascular field of medicine relates to the diagnosis, management and treatment of diseases affecting the arteries and veins. Even when healthy, the anatomy of these vessels is complex, with numerous divisions leading into progressively smaller branches. Development of disease within these vessels often complicates matters by altering their caliber, flexibility, and direction. The interior, or lumen, of a blood vessel may develop constrictions, known as stenoses, and at times may even be obstructed, as a result of the development of atherosclerotic plaques or by the occurrence of tears or lacerations in the vessel wall, known as dissections. These obstructions may complicate the vascular anatomy by leading to the formation of new collateral pathways that establish new routes around the obstructions in order to provide blood flow down-stream from the blockage.  
         [0004]     In order to diagnose and treat vascular diseases, a physician may in many instances perform a diagnostic or interventional angiogram. An angiogram is a specialized form of X-ray imaging, requiring physical access into a vessel with some form of sheath, needle or guide in order to allow a contrast dye to be injected into the vasculature while X-rays are transmitted through the tissue to obtain an image. The contrast dye illuminates the interior of the vessels and allows the physician to observe the anatomy, as well as any narrowings, abnormalities or blockages within the vessels. At times, more selective angiograms are used to delineate a particular area of concern or disease with greater clarity. Access to these more selective areas often requires the insertion of guidewires and guide catheters into the vessels.  
         [0005]     Vascular guidewires and guide catheters can be visualized from outside the body, even as they are manipulated through the body&#39;s vascular system, through the use of continuous low-dose fluoroscopy. The negotiation of the complex vascular anatomy, even when healthy, can be difficult, time consuming and frustrating. When narrowed or obstructed by disease, the vessels are even more difficult—and sometimes impossible—to negotiate.  
         [0006]     Attempts to address and overcome the difficulty of negotiating vascular anatomy have led to various devices, primarily guidewires and guide catheters, for assisting physicians. The devices vary in shape, diameter and length. In order to negotiate the smaller blood vessels as well as to provide some standardization within the industry, for example, many catheterization systems are sized to cooperate with guidewire diameters of 0.035″ or less (0.018″ and 0.014″ being the next most common sizes).  
         [0007]     The tips of these devices may be pre-formed into any of a variety of shapes to help negotiate obstacles or turns within the vasculature having particular geometries. For example, if the tip of a straight guidewire cannot be turned into the opening of a branch vessel, a guiding catheter with a tip having a 30 degree angle may be placed coaxially over the guidewire and used to point the tip of the wire into the appropriate orifice. Once the wire is in place, the catheter can be removed and the wire advanced further until the next obstacle is encountered at which time the guiding catheter is re-advanced into position.  
         [0008]     A distinct disadvantage of these pre-formed devices is a need to constantly exchange and substitute different devices throughout the procedure. Changing of devices generally requires either that a catheter be withdrawn from the vasculature, while the collocated guidewire remains in position, and then be fully disengaged from the stationary guidewire; or, alternatively, that a guidewire be removed while the catheter remains in place, and substituted with a different guidewire. This exchange is not only time-consuming, but can also be dangerous: repetitive passage of these instruments within the vasculature can injure a vessel wall or release an embolic particle into the bloodstream that could lead to stroke, loss of limb, or even death. In an attempt to address and overcome these problems, catheters and guidewires have been developed to allow a practitioner to control, or at least to alter, the tip of the device in a more direct fashion. By means of an external control, the tip of the wire or catheter is turned, bent, flexed or curved.  
         [0009]     Two types of approaches are currently used to impart the control of the wire/catheter tip: (1) direct mechanical linkage and (2) shape memory alloys (SMAs). The direct mechanical linkage approach employs actuators (e.g., wires, tubing, ribbons, etc.) that extend the full length of the guidewire/catheter. Manipulating the external, proximal portion of the control actuator, displaces the distal, internal portion of the wire. Specifically, the direct mechanical linkage can be disadvantageous in that when it is activated to deflect a guidewire&#39;s tip, it can impart a stiffening, shape-altering, performance-limiting constraint on the guidewire as a whole, thereby limiting its functionality.  
         [0010]     The SMA approach involves use of alloys that are typically of metals having a Nickel-Titanium component (e.g., Nitinol) that can be trained in the manufacturing process to assume certain shapes or configurations at specific temperatures. As the temperature of a shape memory alloy changes, the structure of the material changes between states and the shape is altered in a predetermined fashion. SMAs are used extensively in the medical field for a variety of purposes, e.g., stents, catheters, guidewires. Typically, the material is trained to assume a specific configuration on warming (e.g., stents) or to return to its predetermined shape after deformation (e.g., Nitinol guidewires.).  
         [0011]     If manufactured in a specific fashion, SMAs demonstrate a negative coefficient of thermal expansion when heated and can be trained to shorten a specified amount of linear distance. By passing an electric current through the material, the material&#39;s electrical resistance produces an increase in the material&#39;s temperature, causing it to shorten. Upon cooling, the alloy returns to its previous length. This characteristic of shape memory alloys has been used to impart a deflection or alteration in the tip of a guidewire or catheter.  
         [0012]     One approach involves an outer sheath, an inner core and several nitinol actuators disposed concentrically about the inner core. These actuators are controlled via an electrical connection with the core wire and conducting wires traveling in parallel with the core itself. A controlling device is attached at the proximal (practitioner) end of the wire. By manipulating the controlling device, such as a joystick, the distal wire tip can be displaced in multiple directions. Another approach provides an end-mounted control device, at the proximal end, having a box shape.  
         [0013]     Another approach involves an array of microcircuits that control two nitinol actuators that slide on an eccentric board with a low coefficient of friction. By altering the amount of actuator that is activated, a more or less bidirectional deflection can be imparted in the guidewire tip. As with the previous example, this device is also controlled by an end-mounted control device.  
       SUMMARY OF THE INVENTION  
       [0014]     The apparatus, methods and systems according to the present invention, in their various aspects, address any of a range of problems associated with the manipulation of catheters and guidewires within vascular systems during invasive diagnostic or interventional radiological procedures or in other fields requiring precisely controlled penetration of narrow passageways. Among other advantages, embodiments of the present invention provide controllers for variable control, steerable guidewires that may have one more of the following advantages: coaxial structure, over-the-wire catheter compatibility, remote controllability, variably deflectable tip, low profile guidewire, controllability by a detachable, side-entry, easily positioned, single-handedly manipulated, combination torque and guidewire tip control device, ergonomic controllability from a position adjacent to the point of entry into the vasculature (or other passageway being accessed), and economical manufacturability. Aspects of the present invention also encompass or facilitate a reduction, or minimization, of the number of guidewire or guide-catheter exchanges necessary to accomplish a designated task or procedure, yielding an advantage not only in terms of the saving of time and other resources, but more importantly in reducing trauma to the passageways in which the guidewire is deployed. The combination of guidewire and controller according to aspects of the present invention allow convenient side-entry and single-handed repositioning of the controller along the length of the guidewire to allow the practitioner to manipulate the guidewire tip at any location along the guidewire, including at or near the point of entry, thereby improving ergonomics, control, efficiency, and ultimately, for medical guidewires, patient safety.  
         [0015]     When used in the field of interventional radiology, the apparatus, systems and methods according to the present invention provide a solution in the form of an economical, completely coaxial, variable tip, low-profile guidewire remotely controlled by a detachable, easily positioned, single-handedly manipulated, combination torque and guidewire tip control device (controller). This device, with which embodiments of the controller according to the present invention may be used, overcomes shortcomings of prior vascular guidewire devices which lack the combination of a fully variable tip, a coaxial wire allowing compatibility with other devices, and a remote control system. Its dual utilization of the outer wrapped wire as a conducting element and structural support enables final low-profile design measurements that permit this system to be used with standard, currently available over-the-wire devices (e.g., stents, angioplasty balloons, and endo-grafts). The variable and controllable nature of the guidewire tip enhances the user&#39;s ability to manipulate the guidewire through difficult anatomy. Therefore, it minimizes the number of guidewire or catheter exchanges necessary to accomplish a designated task or procedure.  
         [0016]     In one embodiment, a vascular guidewire and control system according to the present invention is a compact, coaxial, remotely and electrically controllable, variable tip guidewire that is fully exchangeable and compatible with most interventional catheter based devices.  
         [0017]     A controller according to another aspect of the present invention provides a side-entry torque device compatible with the steerable guidewire according to the present invention, permitting single-handed repositioning of the controller along the guidewire, while reducing or minimizing trauma to the guidewire&#39;s electrical conducting wires. In addition to meeting criteria for the strength of the grip the controller applies to the guidewire, it offers several additional advantages. According to one aspect of the invention, the controller is provided with a switch that can be operated by the user to energize the steerable tip at the distal end of the guidewire to which the controller is affixed. This arrangement (among others according to the invention, discussed below), permits repositioning of the guidewire, by axial displacement, rotation and tip deflection, by the practitioner using a single hand. According to another aspect, the controller includes a fully detached collet adapted to engage with the body of the controller and a cap of the controller in order that the collet grip the guidewire with a uniform distribution of inwardly radial force. That is, the load each prong or face of the collet, of which there may be two or more, applies to the guidewire is uniformly distributed in a direction parallel to the axis of the guidewire, thereby reducing or minimizing the possibility of damage to the guidewire in the region where it is being gripped by the controller.  
         [0018]     In an embodiment of another aspect of the present invention, the controller can easily be attached or detached and moved freely along the surface of the guidewire, which in turn allows a completely coaxial guidewire structure. In addition, the coaxial guidewire structure permits its unhindered use within existing types of catheters, sheaths and vessels. In other words, the guidewire can be made to be free of any permanent, designated attachment sites along its length. Thus, when the controller is removed, the guidewire has an unhindered, low-profile state with a uniform design diameter extending from the distal guidewire tip to the proximal guidewire end. The substantially uniform diameter guidewire configuration in an embodiment of an aspect of the present invention enables easy exchangeability with other guidewires and catheters, since catheters, sheaths, balloons or other devices can be readily slid over, or removed from, the guidewire.  
         [0019]     In an embodiment of yet another aspect of the present invention, a controller, referred to above, comprises a combined torque and variable control device, which allows precise control of a guidewire tip, while retaining an ability to reposition and manipulate the guidewire in a mechanically advantageous position near the guidewire entry site into the sheath or catheter. As described above, the controller&#39;s easy attachment or removal at the closest possible point to the variable tip of the guidewire provides greater controllability of the tip. An embodiment of the invention permits flexible coupling of the controller to the guidewire, precise guidewire control, as well as a uniform diameter, purely coaxial guidewire system.  
         [0020]     In an embodiment of a further aspect of the present invention, a guidewire controller comprises a guidewire torque control device combined with a switch, preferably of ergonomic design, for energizing the deflectable catheter tip. This combination permits the controller to be used to torque the guidewire, and to deflect or relax the guidewire tip, single-handedly. This combined configuration allows a precise manual guidewire control, aided by the tactile feedback of the distal guidewire tip, to help negotiate difficult anatomy or obstacles.  
         [0021]     In an embodiment of another aspect of the present invention, a controller for facilitating manual control by a user of a guidewire comprises a housing having a primary axis and a first engagement feature substantially along the primary axis, a second engagement feature, non-parallel to the first engagement feature adapted to receive the guidewire, and a third engagement feature parallel with the first engagement feature for accommodating a portion of the guidewire. One or more of the engagement features may comprise slots. Furthermore, the second engagement feature may be perpendicular to the first engagement feature.  
         [0022]     The invention, in yet another embodiment, provides a switch coupled to an electrical circuit causing the flow of electricity to the tip of a guidewire, wherein the switch may be held and/or manipulated by the user in conjunction with a controller for the guidewire in a single hand.  
         [0023]     In an embodiment of another of its aspects, the invention provides a method of using a controller to displace, rotate, or deflect the tip of a guidewire using a single hand, comprising the steps of aligning a non-parallel engagement feature with the guidewire so that the controller is in a first position, engaging the guidewire with the non-parallel engaging feature, and shifting the controller to a second position in which the guidewire is fully received by the controller. The first position may or may not be perpendicular to the second position.  
         [0024]     The various aspects of the present invention can be used in concert with guidewires, energizers, switches and according to methods that are the subject of co-pending applications entitled: Vascular Guidewire System, U.S. application Ser. No. 11/090,589; Energizer for Vascular Guidewire, U.S. application Ser. No. 11/090,588; Method for Use of Vascular Guidewire, U.S. application Ser. No. 11/090,512; and Vascular Guidewire Control Apparatus, U.S. application Ser. No. 11/090,574; all filed on Mar. 24, 2005, the contents of which are incorporated herein by reference in their entirety. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]      FIGS. 1A-1F  show aspects of an embodiment of a guidewire according to the present invention.  
         [0026]      FIGS. 2A-2G  show aspects of an embodiment of a guidewire controller in accordance with the present invention.  
         [0027]      FIGS. 3A-3D  show aspects of an embodiment of a guidewire power source or energizer according to the present invention.  
         [0028]      FIG. 4  shows aspects of a second embodiment of a guidewire controller according to the present invention.  
         [0029]      FIGS. 5A-5C  show more detail of aspects of the embodiment of the controller shown in  FIG. 4 .  
         [0030]      FIGS. 6A-6B  show a shaft, body, or housing portion of a second embodiment of a guidewire controller according to the present invention.  
         [0031]      FIGS. 7A-7C  show a cap portion of a second embodiment of a guidewire controller according to the present invention.  
         [0032]      FIGS. 8A-8C  show a controller assembly in an embodiment of the present invention including a shaft or housing portion according to the embodiment shown in  FIGS. 6A-6B , a cap portion according to the embodiment shown in  FIGS. 7A-7C  and a collet portion according to the embodiment shown in  FIGS. 9A-9E .  
         [0033]      FIGS. 9A-9E  show a collet portion of a second embodiment of a guidewire controller according to the present invention.  
         [0034]     FIGS.  10 A-B show aspects of an embodiment of a controller assembly including a shaft or housing portion having an engagement feature adapted to receive a guidewire along its side at a location near the point of entry.  
         [0035]     FIGS.  11 A-B show aspects of an embodiment of a switch used in conjunction with a guidewire controller according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0036]      FIGS. 1A-1F  show various views of an embodiment of a guidewire  1  according to the present invention. Guidewire  1 , shown fragmented in  FIG. 1A  to permit the entirety of the guidewire to be shown in one figure, comprises three main sections. Guidewire  1  includes an elongate, tubular structure, having a proximal end  6  (see  FIG. 1F ) which resides exterior to the body of a patient (or other passageway with which guidewire  1  is being used) and physically handled by a practitioner, and a distal end, which in use will be within the passageway, having an actuator portion  2 . The actuator portion  2  at a most distal portion of the guidewire  1  comprises a shape memory alloy (SMA)  12  or other suitable component adapted to introduce a deflection in a tip of guidewire  1 , when activated. A third, central or mid-portion  4  of guidewire  1  is that section of the guidewire  1  between, and coupling, the distal and proximal portions and contains an inner, centrally disposed, electrically insulated, conductive wire  8 . This wire, according to an aspect of the present invention, may be provided with a gradually tapered diameter as it progresses toward the distal tip of the guidewire. In the presently illustrated embodiment, the proximal end  6  of the guidewire  1  demonstrates where the inner wire  8  extends beyond the outer wrapped wire  10  and is exposed so as to be available for electrical connection to the controller device  46  and  150  as described below and illustrated in the accompanying figures.  
         [0037]      FIG. 1A  includes a more focused view of the mid-portion  4  of the guidewire  1  in an embodiment of an aspect of the present invention. The inner core wire  8  is a centrally disposed, electrically insulated, conductive wire having a gradually tapered diameter as it progresses toward the distal tip of the guidewire. Electrical insulation for the inner core wire  8  can be any of a variety of different suitable materials, but, in an embodiment of this aspect of the present invention, the insulation is preferably provided with a very low profile to accommodate the small diameter of the guidewire  1 . In one embodiment, the insulation may be of a paralyene or polyamide coating of the type often used in medical indications. In another, an enamel coating similar to that used on magnet-wire could be used, as could other suitable materials.  
         [0038]     In another aspect of the present invention, core wire  8  eventually tapers from a cross-section dimension that almost entirely fills the lumen of the outer wrapped wire  10  near the proximal end  6  of the wire to an appreciably smaller diameter as it progresses toward the distal end. Core wire  8 , however, in this embodiment, may not necessarily extend to the most distal extent of the outer wrapped wire  10 . Moreover, the full extent of the inner wire  8 , its tapering characteristics and the selection of its composition can be varied to form embodiments exhibiting differing mechanical behavior at the tip of the guidewire  1 , including but not limited to the magnitude and speed of deflection, stiffness, resiliency, and other characteristics. Some candidates for core wire  8  include, without limitation: NiTi based wires or steel musical wires with variable material characteristics of elasticity, resilience and ductility.  
         [0039]     In an embodiment of one aspect of the present invention, the outer wrapped wire  10  serves dual functions. First, it provides a support layer which happens to be on the exterior of the guidewire  1 . In this capacity, it provides mechanical structure sufficient for the wire to provide pushability, torquability and flexibility for proper use. In this embodiment, the outer wrapped wire  10  is constructed of a single filament wire, capable of electrical conduction, yet insulated in a similar fashion to the inner core wire  8 . In one embodiment, the filament is a 304v stainless steel filament with a paralyene or similar insulating coating. In another embodiment, the filament is an approximately 34 to 36 AWG tin or copper wire, with an enamel insulating cover. Other suitable filaments, with or without coatings, may also be appropriate.  
         [0040]     When in a helical configuration according to one aspect of the present invention, the outer wrapped wire  10  forms a tubular structure having a hollow lumen arising from its being wrapped/coiled in a tight, uniform diameter, helical fashion. In one example, outer wrapped wire  10  is sufficiently tightly coiled to possess a final maximal diameter less than or equal to about 0.035″. Other arrangements of the outer wrapped wire  10 , whether modified helical or non-helical arrangements, or even if tubular, woven or of other outer surface layer configuration, are also possible and within the scope of the present invention. Regardless of the precise wrapping configuration, the outer wrapped wire  10  in one embodiment extends from the most distal extent of the guidewire almost to the proximal portion of the guidewire.  
         [0041]     Secondly, the outer wrapped wire  10  in an embodiment of an aspect of the present invention serves as an electrical path (e.g., return) for the actuator  12 . The outer wrapped wire  10  forms an electrical connection with the distal end of actuator  12  at the end cap  18  as described below. Being electrically insulated, as described above, outer wrapped wire  10  remains electrically separated from the actuator  12  and the inner core wire  8 , preventing short circuiting. At or near a proximal attachment site  14  of actuator  12 , described below, the insulation of the outer wrapped wire  10  is selectively removed, exposing an electrically conductive portion of this wire  10 . The outer surface of this insulation can be selectively removed in the manufacturing process by direct abrasion, chemical dissolution or other suitable process. The result of such process is an electrically conductive exposed surface, that nevertheless maintains electrical separation from any inner structures.  
         [0042]     In another embodiment, the connection points of the actuator  12  could be reversed, such that the proximal attachment site  14  connects the outer wrapped wire  10  with the proximal end of actuator  12  while the distal end of actuator  12  is connected to the inner core wire  8 . The described embodiment provides an actuator  12  that is straight when in a resting, unactuated state. This arrangement accommodates insertion and navigation of the guidewire  1  through the vasculature to a point where the sort of precise control enabled by the various aspects of the present invention can be deployed. In an alternative embodiment, not shown, that is also within the scope of the present invention, the actuator  12  could be in a non-straight or flexed condition when in a resting or non-energized state, and then return to a straightened position as the actuator  12  is energized by the user.  
         [0043]     In another embodiment, shown in  FIG. 1F , the guidewire  1  includes an inner core wire  8  (which, per  FIGS. 1A-1C  is connected at its distal end with the actuator  12 ) as well as a separate inner conducting wire  11 . Inner conducting wire  11  is distinct from the inner core wire  8  and connects the proximal end of the actuator  12  to the proximal end of the outer wrapped wire  10 , effectively bypassing a portion of the outer wrapped wire  10  in order to provide a decreased electrical resistance for the guidewire and actuator assembly. At the proximal portion  6  of the guidewire  1 , this inner conducting wire  11  may be attached (e.g., without limitation, via soldering) or otherwise placed in direct or indirect electrical communication with the outer wrapped wire  10 , such that a complete electrical connection can be made at the proximal portion  6  of the guidewire  1 , e.g., at the proximal tip  17 , via the energizer and switch.  
         [0044]      FIG. 1F  shows the extension of inner core wire  8  beyond the most proximal portion of the outer wrapped wire  10 , in an embodiment of an aspect of the present invention. The exposed inner wire  8 , with its insulation removed at this location, facilitates attachment of an electrical contact  20 , such as an alligator clip, of a controller (described below) in order to complete an electrical circuit for the guidewire tip actuator  12 . Outer wire  10  includes insulation  9  that is removed in a proximal portion  11 . In use, the portion labeled  13 , uninsulated, would serve as an electrically negative (or positive) connection point, while the uninsulated portion of the exposed inner core wire  8 , to which the reference numeral is directed in  FIG. 1F , would serve as an electrically positive (or negative) connection point.  
         [0045]      FIGS. 1B and 1C  show, among other features, the variable tip portion of the guidewire  1  in an embodiment of the present invention. The actuator  12  is a portion of the guidewire  1  that provides a mechanical force for deflecting the distal tip  2  of the guidewire  1 . In this embodiment, actuator  12  comprises a fine wire constructed of a shape memory alloy (SMA). These alloys, as discussed above, most typically consist of a nickel-titanium (NiTi) based metal wire having a negative coefficient of thermal expansion, but may consist of different alloys. When heated, these alloys may contract a certain percentage of their overall length. Being electrically conductive, but having a comparatively high electrical resistance, they become heated when an electrical current passes through them and so contract linearly. When an applied current is switched off, the alloy cools and returns to its prior length. Typically, an alloy of this sort can tolerate thousands of repeated contraction and expansion cycles. In addition, SMAs are available in various diameters, lengths, surface coatings and characteristics. In one embodiment, a guidewire actuator  12  according to the present invention comprises a wire of SMA having a diameter of about 0.004″. Other dimensions are possible and may be selected for particular guidewire characteristics. By altering the actual length and diameter of the actuator  12 , different tip deflections can be configured to meet specific clinical situations.  
         [0046]      FIG. 1D  demonstrates an overall view of the distal tip  2  with an enlarged view of its proximal portion in an embodiment of an aspect of the present invention showing the actuator&#39;s proximal attachment site  14 . The insulation on the inner core wire  8  is removed at this attachment site to provide an electrical contact with the actuator  12 . The surface coating of the proximal actuator  12  is also removed to improve the connection. NiTi—and possibly other SMA-based wires may be difficult to attach via standard solder/weld methods and appear to be best connected via a mechanical means such as crimping or tying. In an embodiment of this sort, a fine mechanical crimp may be applied to attach the actuator to the inner core wire. An alternative embodiment would involve creating a divot in the inner core wire  8 , about which the actuator  12  could be knotted. In yet another embodiment, a spot weld or conductive epoxy would fix the wire  8  at this site. Various methods for attaching actuators  12  to inner core wires  8 , outer wrapped wire  10  or inner conducting wire  11 , may provide a suitable a mechanical and electrical connection between the components of the guidewire  1 .  
         [0047]     In an embodiment of another aspect of the present invention, referring again to  FIGS. 1B and 1C , the distal end of the actuator  12  is mechanically and electrically coupled at its distal attachment site  16  to the outer wrapped wire  10  in an eccentric (i.e., off-center) fashion. As shown in  FIG. 1B , actuator  12  progresses from a central location  15  on the inner core wire  8  at its proximal attachment site  14 , to an eccentric location at its distal attachment site  16  to the distal outer wrapped wire  10 . This slight offset facilitates a mechanical advantage by which the actuator  12  can impart a deflection in the distal tip  2  of the guidewire  1 . At the point of connection  16  between the outer wrapped wire  10  and the actuator  12 , the insulation is removed from the outer wrapped wire to facilitate the electrical connection with the actuator  12 . The mechanical connection is accomplished by crimping/compressing the actuator  12  to the outer wrapped wire  10  with the end cap  18  (shown in  FIG. 1A ). Alternative means of connection as listed above for the proximal attachment site could also apply to the distal attachment site.  
         [0048]      FIGS. 2A-2G  depict various views of a variable tip guidewire control mechanism (controller)  46  in an embodiment of another aspect of the present invention. The illustrated embodiment of the controller  46  provides a self-contained, dual purpose device capable of controlling the deflection of the guidewire tip  2  while also serving as a torque controller. In addition, as described below, the controller can be placed or repositioned anywhere along the length of the proximal end of the guidewire  1  to permit control of the axial progression or withdrawal of the guidewire  1 . Controller  46  thus enables direct, inline, single-handed, fingertip control of the guidewire  1  at any point along the proximal portion of the guidewire  1  and external to the object, or medical subject, undergoing a procedure with the guidewire  1 .  
         [0049]      FIG. 2A  provides a plan view of controller  46  and FIGS.  2 B and  2 C- 2 F side and end sectional views, which are exploded views to detail the interior of the device. The long axis of the controller  46  runs parallel with and is adapted to receive the guidewire  1  in a lateral fashion. When the controller  46  is in use, the guidewire  1  is seated in the guidewire channel  22 . Guidewire channel  22  runs the full length of the controller  46  and its diameter is commensurate with the diameter of the guidewire  1  being used to permit an effective mating fit of the guidewire  1  within the controller  46 , as elaborated upon below. With a latch  24  in an open position, access to the guidewire channel  22  is achieved via slot  26 . This slot  26  extends the full length of the controller  46 , with the exception of the region of a grasper swing door  28 . The grasper swing door  28  is mounted via hinges  30  and fastened in a closed position by latch  24 . With the guidewire  1  seated in place in the guidewire channel  22 , the grasper swing door  28  can be placed in a closed position. In the closed position, a grasper mechanism  32  is placed firmly in contact with the guidewire  1 , to permit torquing or linearly loading the guidewire  1 .  
         [0050]     As seen in  FIG. 2G , the grasper mechanism  32  includes a set of metal prongs  34 , e.g., without limitation, three in this embodiment, which may be of any suitable material, including but not limited to copper, brass, steel or other suitable electrically conductive material (if it is to provide an electrical connection in accordance with an aspect of the invention in the presently illustrated embodiment). In other embodiments where the actuator  12  will be energized by other means, the prongs may be of plastic, resinous or other suitable non-electrically conductive material. The prongs  34  may be positioned in order to circumferentially surround the guidewire  1  and thereby allow firm contact and grasping of the guidewire  1 . Prongs  34  may be buttressed at their respective bases  52 , such that they protrude slightly into the lumen of the guidewire channel  22 . Therefore, when the grasper swing door  28  is closed, the prongs  34  are urged into contact with the guidewire  1 . This arrangement serves two key functions. By firmly grasping the guidewire  1 , controller  46  permits a torque to be applied to the guidewire  1  surface allowing the guidewire tip  2  to be rotated through 360 degrees in order to facilitate negotiation of obstacles. Additionally, the positioning of a grasper mechanism prong  34  at a 12:00 position on guidewire  1  facilitates an electrical connection with the exposed surface of outer wrapped wire  10 . Thus, when slide switch  36  is moved forward by the user, switch contact  38  on the switch  36  touches contact  40 , which is connected to the 12:00 grasper prong  34 . The slide switch contact  38  is in electrical communication with the positive pole of battery  42  via an insulated, flexible wire  44 . The negative pole of battery  42  is then connected to the attachment wire  48 . The attachment wire  48  then extends from the controller  46  as a flexible external wire connected to attachment device  20  (such as an alligator clip). This attachment device  20  may then be clipped or otherwise electrically and mechanically coupled to the exposed portion of inner core wire  8 . The slide switch  36  is therefore the means for activating the deflection of the guidewire tip  2 . When slid into the forward position, slide switch  36  causes a complete electrical connection to be set up between the battery  42  and the actuator  12 .  
         [0051]      FIG. 2G  depicts a method for operation of a guidewire  1  system in an embodiment of another aspect of the present invention. The controller  46 , described above, is a separate physical entity from the guidewire  1 . The distal portion and then the body portion of the guidewire  1  are introduced into the vasculature (or other passage way, for non-vascular guidewires) at a point of entry  60  in any of the standard ways known to those familiar with these techniques. The guidewire  1  can be manipulated by itself without the need for the control mechanism according to the present invention until the user reaches a point where the guidewire  1  can not be further negotiated through the vasculature, either secondary to the nature of the native anatomy or due to a diseased state such as a stenosis or obstruction. At this point the user has the option of using the controller  46  according to the present invention. Referring to  FIG. 2B , the controller&#39;s connection wire  48  is first attached to the exposed portion of the inner core wire  8  via attachment  20 . The user can then attach the controller at any point along the guidewire  1  that is convenient. As discussed above, the side entry feature of the controller  46  enables a user attach and remove the controller  46  from the guidewire  1  without needing to do so coaxially.  
         [0052]     In order to attach the controller  46  to the guidewire  1 , the grasper swing door  28  is unlatched and placed in the open position. The controller  46  is then placed on the guidewire  1  by means of the side-entry feature provided by the slot  26 . The slot  26  directs the guidewire  1  into the guidewire channel  22 . The guidewire channel is formed proximal as well as distal to the grasper mechanism  32 , ensuring that the guidewire  1  is adequately supported until the grasper swing door  28  is closed. When the user is satisfied with the location of the controller, the grasper swing door  28  is closed and latched by means of the latch  24 . The guidewire  1  is now firmly grasped in position. When the user slides the switch  36  forward, the actuator is energized as described above. This energized state permits current to flow to, and through, the actuator  2 , thereby imparting a deflection on the guidewire tip  2 . The degree and ultimate configuration of the deflection depends on several factors, including: the duration of activation, power source characteristics, and design considerations of the guidewire tip  2  (e.g., the length and diameter of actuator  12  and length of inner core wire  8 ).  
         [0053]     In an embodiment of another aspect of the present invention, by rotating an attached controller  46 , while simultaneously energizing the actuator  12  (by moving switch  36  in an ON position), the user can manipulate the guidewire tip  2  through the anatomy or past an area of disease. The same can be done with alternative embodiments, including such as are described below. When the slide switch  36  is returned to its off position, the actuator  12  is de-energized, allowing the guidewire tip  2  to return to its original position. This procedure can be repeated for thousands of cycles. The controller  46  can easily be repositioned on the guidewire  1  by releasing the latch  24 , sliding the controller to the desired position and then re-latching the grasper swing door  28  (or as otherwise permitted by the particular mechanical design of the detachable controller, including one or more configurations described below). When it is not needed, the controller  46  can be removed entirely from the guidewire  1  without difficulty.  
         [0054]     In an alternative embodiment illustrated in  FIG. 2A  (shown in dashed lines) the power source  56  for the controller  46  can be housed in apparatus separate from the controller device  46 .  
         [0055]     Another aspect of the present invention concerns the profile of the distal tip of the actuator  12 , which in an embodiment of this aspect of the present invention is tapered. A wide variety of profiles are possible, and may be selected among to arrive at configurations suitable for particular design criteria for the guidewire  1 . The deflection characteristics of the distal end of the guidewire  1  can be altered by appropriate selection of the design parameters of the distal tapered portion of the inner core wire  8 . See, for example,  FIG. 1E . Narrowing the distal taper, for example, will generally impart a tighter curve radius. This design principle according to the present invention can be used for different guidewires  1  as well as for differing uses, such as for accessing the renal arteries versus the carotid arteries.  
         [0056]     A set of profile geometries that have been considered, but without limitation, are set forth in the table below. Included are two predominant cross-sectional shapes, oval and D-shaped (here, semicircular), with a listing of widths, heights (for the oval profiles), cross-sectional areas and lengths.  
                                                                                                             ACTUATOR TIP PROFILES                            CROSS-                       SECTIONAL           WIDTH   HEIGHT   LENGTH   AREA       DIMENSIONS   (INCHES)   (INCHES)   (INCHES)   (INCHES)                    OVAL            1   0.010   0.0039   0.25   3.9E−5       2   0.010   0.0039   0.5   3.9E−5            D-SHAPED/SEMICIRCULAR            1   0.008   see width   0.25   2.5E−5       2   0.10   see width   0.25   3.92E−5        3   0.008   see width   0.25   2.5E−5                  
 
         [0057]     In accordance with an aspect of the present invention, an actuator tip having a D-shaped cross-sectional profile advantageously permits onset of curvature of the tip in a preselected direction. Actuator tips having an asymmetrical cross section have a preferential direction of curvature when subjected to axial loading upon energizing of the actuator. D-shaped or semicircular cross sections tend to initiate curvature consistently about the flat side of the “D” or semicircle. Among other advantages, a profile having this general configuration will tend to repeatedly curve in the same direction, so that a user that happens to be holding the guidewire  1  in a particular orientation need not “recalibrate” with each energizing of the actuator  2 .  
         [0058]     Many alternative embodiments of the actuator  2  are within the scope of the present invention. In one example, an actuator wire  12  according to the present invention makes use of a pulley-type of mechanism, whereby an end of the actuator  2  is attached to the inner core wire  8  as before. The insulated wire  12  is then looped around the distal end of the outer wrapped wire  10 , rather than being fixed at that location. Insulated wire  12  is then run in parallel to itself and attached more proximally  54  to the outer wrapped wire  10 , as shown. This arrangement enables a doubling effect of the actuator force as it shortens over a given distance. A greater degree of force can then be used to impart different configurations on the guidewire tip  2  than might be possible in other embodiments of this aspect of the present invention.  
         [0059]      FIGS. 2B-2F  show an embodiment of a latch mechanism for controller  46  according to the present invention. This embodiment involves a compressive internal latch mechanism rather than an external latch as described above. This embodiment could offer improved single-handed operation of the controller  46  and guidewire  1 . The latch is engaged in a simple manner by closing and squeezing the grasper swing door  28 , that is, with guidewire  1  mounted in the controller  46 . To release the latch, the door is compressed a second time, thereby releasing the hooking mechanism and allowing the grasper swing door  28  to open again.  
         [0060]     In still another embodiment,  FIG. 2G  shows an integrated “all-in-one” system that does not require an external connection wire  48 . The controller  46  uses the outer wrapped wire  10  in a similar fashion to the embodiment described above, while a second, pointed, penetrating contact point  58  on the controller penetrates in-between the coils of the outer wrapped wire and makes contact with the inner core wire  8 . This contact is connected to the opposite pole of the battery by a wire. This would allow a complete electrical circuit to occur when the slide switch  36  is activated, thereby facilitating deflection of the guidewire tip.  
         [0061]     Yet another embodiment of various aspects of the present invention is shown in  FIG. 1D . As shown in the upper portion of Figure ID a fine inner conducting wire  11  is provided in coaxial location within the outer coil  10 , permitting the electrical return current to be transmitted with less resistance, lowering the total power necessary to activate the actuator  12  at the distal end of the guidewire  1 . This electrically insulated inner conducting wire  11  is electrically connected to the proximal end of the actuator  12  via an electrical connection that is insulated from the inner core wire  8 . This inner conducting wire  11  tracks along the surface of the inner core wire  8  and is electrically coupled to the proximal end of the outer coil  10 . The attachment of the proximal end of the wire  11  to the power source (not shown) can then still be made using the outer coil  10  as the conducting surface. This inner conducting wire  11  may be composed of a highly conductive material capable of transmitting a current with very little drop in resistance, despite its fine diameter. An example of this material, without limitation, would be a MP35N-DFT having a Silver core. A potentially suitable diameter, without limitation, would be in the range of 0.002″. Both of the electrical connections of the guidewire  1  to the external power source can occur at the proximal end of the guidewire  1 .  
         [0062]     Another aspect of the present invention concerns an energizer and connection system  100  providing a mechanism for attaching the proximal portion of the guidewire  1  to a power source, the energizer  110 . In order to obtain a completely coaxial system, the proximal portion or end of the guidewire  1  should preferably fall within design tolerances, e.g., diameter, for the remainder of the wire. This arrangement allows for therapeutic and diagnostic catheters and devices to be axially or coaxially mounted over the (free) proximal end and coaxially track over or ensheathe the guidewire  10 . An embodiment of this aspect of the present invention is shown in  FIGS. 3A-3D  and  FIG. 4 . The proximal portion  6  of the guidewire  1  is formed of an outer wrapped wire  10 , having a protruding inner core wire  8 . The inner core wire  8  is electrically insulated from the outer core wire  10 . The proximal tip  17  (as seen, e.g., in  FIG. 1F ) of the inner core wire  8  has little or no insulation, such that it may make electrical connection with a connection jack  120 . The proximal portion of the outer wrapped wire  10  also lacks insulation, such that it may also make electrical contact with a different portion of the connection jack  120 . Therefore, these two distinct connection points on the guidewire are able to make an electrical connection between the guidewire  1  and the connection jack  120  in order to allow delivery and return of electrical current while still meeting the design requirements of a low profile, coaxial system. Thus, this embodiment of a connection system  100  according to the present invention still employs the essential characteristics of the guidewire  1  described above, namely using of the inner core wire  8  and the outer coil wire  10 . The inner conducting wire  11 , in an embodiment of this aspect of the present invention, merely provides a more efficient transmission of power from the distal actuator  12  to the proximal end  17  of the outer coil  10 .  
         [0063]     An embodiment of another, related aspect of the present invention, a power source for activation of the guidewire  1  is shown in  FIGS. 3A-3D . A controller  46  (or, per the description below,  150 ) provides improved tactile feedback and ease of manipulation of the guidewire  1  when it is as light as possible. Therefore, housing a battery-type power source within the housing of the controller  46  itself may not be preferred, though it is within the scope of the present invention. A power source or energizer  110 , in an embodiment of an aspect of the present invention, may itself be separate from the controller  46  or  150  in a fashion similar to that described in the embodiment shown in  FIG. 2A . The power source or energizer  110 , shown in  FIGS. 3A-3D , includes a connection jack  120  to accept the positive and negative terminals of the guidewire  1 , a power source in the form of one or more batteries  130 , and connecting wires that couple a detachable switch on the controller  46  or  150  to the power source or energizer  110 .  
         [0064]     In an embodiment of this aspect of the present invention, the connection jack  120  of this system allows insertion of a length of the proximal end  17  and a proximal portion of the guidewire  1  so that an electrical connection can be made between the outer core wire  10  and the inner core wire  8 . Other arrangements are also possible, including but not limited to a distinct connector element adapted to mate with jack  120 , but should preferably have an external diameter not substantially greater than a maximal diameter of the guidewire  1 . The power source or energizer  110  also provides a means to mechanically grasp and stabilize the proximal portion or end  17  of the guidewire  1  during use. In an embodiment of this engagement mechanism  112  according to the present invention, the mechanism is slidably operable with a thumb or finger to releasably engage the proximal end or tip of the guidewire. The power source or energizer  110  is light enough such that as the guidewire  1  is advanced, the power source or energizer  110  is easily pulled with the guidewire  1 . Or, the guidewire  1  may be looped around the power source or energizer  110  to build slack into the guidewire  1  and reduce or minimize the necessary movement of the power source or energizer  110 . The power source or energizer may be provided with a recess or slot  124 , or other suitable mechanism, for receiving a portion of the guidewire  1  in order to enhance stability of the guidewire  1  during its use. The power source of energizer  110  may also be provided with a mechanism  114  (which as shown may, but need not, be on the engagement mechanism  112 ) for temporarily gripping the proximal portion or end of the guidewire. The connection jack  120  also allows 360 degrees rotation of the guidewire  1  within the power source or energizer  110  to allow the user, via controller  46  or  150 , to torque the guidewire  1  without limitation. The mechanical connection may occur in a variety of means including through the use of an electrically conductive gripping spring, socket or latch. This jack  120  is electrically connected to the power source or energizer  110 . Based on the anticipated power requirements, the power source or energizer  110  may be varied. In one embodiment, two wires exit the energizer  110  and are connected via wire(s)  122  to the switch, e.g.,  26  or  160 . When the switch  36  or  160  is closed, electrical current flows from the battery, e.g.,  130 , through wire(s)  122  and the switch, e.g.,  160 , to the guidewire  1  with the resultant activation of the distal tip.  
         [0065]     In another embodiment, the switch  160  may be configured to be attachable to the controller  150 . The switch  160  may be of circumferential geometry, with a slot provided along one side. This slot is sized to accommodate the side-entry ability of the controller  150 . The switch  160  could be placed over the guidewire  1  and then advanced onto the back end of the controller  150 , where it would lock into position on the controller  150 . When the switch  160  is not necessary for use of the guidewire  1  during a particular procedure, the switch  160  can be removed from the controller  46  and be placed or stored elsewhere. This removability, in this embodiment, may permit greater versatility of use. In various embodiments, the switch  160  may, for example, incorporate a rubberized, bladder type switch with two near-circumferential contacts. This embodiment, shown in  FIGS. 4 and 5 A- 5 C, allows a user to activate the switch  160  at any point on its circumference, providing the user with simple, ergonomic control of the switch  160 .  
         [0066]     In another embodiment of the switch  160 , the switch  160  is not configured to be attachable to the controller  150 . Rather, it is ergonomically designed to be separate from the controller  150  and held in the practitioner&#39;s hand in conjunction with, but separate from, the controller. This still allows single-handed control of the distal tip of the guidewire  1 .  
         [0067]     In another embodiment, shown in FIGS.  11 A-B, the switch can be designed to sit in the user&#39;s hand while being held by, for example, just the fourth and fifth fingers, or even a single finger. According to this embodiment, the switch may be composed of a polymer or elastic material known or used in the art, and may consist of two halves or portions as shown in  FIG. 11B . Furthermore, as shown in  FIG. 11A , the switch may have a curved surface  610  adapted for the contour of the user&#39;s fingers gripping the switch, and a related, convex surface  620  accommodated for the palm or portion of the user&#39;s hand adjacent to the fingers holding the switch. Thus, use of the fourth and fifth fingers to hold the switch according to this embodiment may include using part of the user&#39;s hand or palm as well. The switch may be activated by squeezing one or both of the surfaces  610  and  620  of the switch when it is placed in the user&#39;s hand as described above. Embedded electronics, not shown in these Figures, may be used to help accomplish such activation. These features of the switch allow the user to maintain simple, ergonomic control of the switch and single-handed control of the distal tip of the guidewire  1 . In this embodiment, the switch may be separate from the controller  150 , but used in conjunction with the controller  150  in a single handed fashion. Furthermore, the switch may be connected to energizer  110  by either a wired or wireless connection.  
         [0068]     Another embodiment of the controller  150  according to the present invention is shown in  FIGS. 4 and 5 A- 5 C. This embodiment employs a side-entry slot mechanism, like the embodiment described above. Rather than the latch type closing mechanism disclosed in that example, however, this embodiment employs a screw-down collet configuration, which may permit a mechanical advantage relative to the illustrated latch-type mechanism. The controller  46  in this embodiment includes three components. The first, shown in  FIGS. 6A and 6B , is a housing, body or shaft  200  having an inner lumen  210  and a side slot  220  along its length. The slot  220  allows for side-entry of the guidewire  1  into the shaft lumen  210 . The distal end  230  of the shaft  200  is provided with external screw-threads  240  for adequate mechanical advantage when engaging a mating, internally threaded cap  300  having mating threads  310 . The shaft  200  may be formed of any number of suitable materials including, without limitation, nylon-based, high grade medical plastics having a comparatively stiff modulus of elasticity.  
         [0069]     According to embodiments of aspects of the present invention, the controller  150  is provided with an engagement feature for enabling, or at least facilitating engagement of the guidewire  1  by the controller  150  using one hand only. In one embodiment, the single handed engagement feature is an engagement slot that is non-parallel to a primary receiving feature (e.g. slot  220 ) of the controller  150 .  FIG. 10B  represents one possible depiction of this embodiment of an aspect of the invention, in which the engagement slot  540  is substantially perpendicular to the primary receiving slot  520 . This depiction represents only one way of achieving the single handed engagement feature of the controller  150 , as other arrangements of the engagement slot  540  and primary receiving slot  520  may also be utilized.  
         [0070]     The side-entry slot mechanism or single handed engagement feature in this embodiment of the controller  150 , or in the embodiments described above, may consist of a slot having three portions: a primary slot  520  parallel to the axis of the controller, a second, engagement slot  540 , which may be non-parallel to the primary slot  520 , for engaging the guidewire, and a third slot  560 , parallel with the primary slot  520  and the controller  150 , for accommodating a portion of the guidewire  1 . As shown in  FIG. 10 , the primary slot  520  may receive a length of the guidewire  1  similar to slot  26  or  220  in the embodiments above. The engagement slot  540 , perpendicular to the primary slot  520  in this illustrated embodiment, is continuous with the primary slot  520  and is similarly adapted to align with and receive a guidewire  1 . Together, these portions of the slot may engage the guidewire  1 . Using a single hand, the practitioner can first orient the controller  150  non-parallel to the guidewire  1  and place the engagement slot  540  over the side of the guidewire  1 . Subsequently, the practitioner can align the primary elongate slot  520  such that it can slide over and finally sit on the guidewire  1 . The practitioner may, during this procedure, maintain control of the guidewire  1  with the other hand, which remains free during engagement of the controller  150 . The engagement slot  540  may function as a fulcrum that facilitates the act of aligning the primary slot  520  over the guidewire  1  and locking the controller  150  onto the guidewire  1 . The “L” shape of the slot in this particular embodiment allows the practitioner to achieve such alignment and repositioning of the controller  150  in an efficient, single handed manner. Furthermore, the advantages of side entry and removal with respect to the guidewire are preserved.  
         [0071]     The second component of the controller  150  is a collet  400 , shown in  FIGS. 8A-8C  and  9 A- 9 C. The collet  400  is configured to slide in an axial fashion within the lumen  210  of the shaft  200. The collet 400 is also provided with a side slot 420 to allow the guidewire 1 to pass within its lumen 410. On the opposite side of the slot 220 of shaft 200 is a spline 250 that fits within a groove on the inner surface of the shaft 200. Therefore, when the collet 400 is within the shaft 200, the collet 400 will not rotate, but will maintain an alignment of the slots 420 and 220, respectively, of the collet 400 and the shaft 200. The distal end 430 of the collet 400 includes at least two prongs. In the illustrated embodiment, but without limitation, the prongs 442, 444, 446, 448, of which there are 4, are formed as part of the collet 400, which slides within the lumen 210 of the shaft or housing 200. Therefore, as the cap 300 is tightened, it compresses the prongs 442, 444, 446, 448 on the front end radially inwardly toward the guidewire 1 in order to grip it. The cap 300 also drives the sliding collet 400 into the shaft 200 as it is tightened. The distal or leading end 230 of the shaft or housing 200 is provided with a reverse bevel 235 so that, as the collet 400 is driven into the shaft 200, the prongs 442, 444, 446, 448, which are provided with respective complementary bevels 437 at their proximal end, are also compressed by this bevel 235 of the shaft or housing 200. This bevel arrangement increases the mechanical advantage of the collet 200 and also allows the prongs 442, 444, 446, 448 to grip the guidewire 1 with a more evenly distributed gripping surface—rather than being gripped at only one point, which can rotate the prongs and cause them to impart undue and damaging point stresses on the guidewire 1 or its components. Distribution of the prongs 442, 444, 446, 448 around the lumen 410 permits their compression to impart a grip on the guidewire 1 when the cap 300 is tightened to engage the bevels 350 of the cap 300 and shaft 200 with the complementary bevels of the prongs 435 of the collet 400. A gripping surface 470 on each prong 442, 444, 446, 448 may be curved, concavely with respect to the guidewire 1, to disperse the compression forces of the respective prong 442, 444, 446, 448 along the surface of the guidewire 1. This dispersion reduces or eliminates a focused, high-pressure contact that could potentially damage underlying electrical components of the guidewire 1. Further, the shaft in this embodiment incorporates a means to lock the removable switch 160 in place.    
         [0072]     A third component of the controller  150  is the cap  300 , shown in FIGS.  5 A,  7 A- 7 C and  8 A- 8 C. As shown in  FIGS. 8A-8C , the cap  300  mates with the shaft  200 . Inner threads  310  of the cap  300  allow for longitudinal motion of the cap  300  along the shaft  200 . The cap  300  also is provided with a slot  320  that is aligned with the shaft slot  220  and collet slot  420  during insertion and removal of the guidewire  1 . As the cap  300  is tightened, the inner bevel  350  of the cap  300  compresses the prongs  442 ,  444 ,  446 ,  448  of the collet  400  down and onto the guidewire  1 . Furthermore, as the collet  400  is driven into the shaft  200 , the proximal bevel  437  of the collet prongs  442 ,  444 ,  446 ,  448  abutting bevel  235  of the shaft  200  provide additional mechanical advantage to compress the prongs onto the guidewire  1 . The cap  300  is constructed of any suitable material having a sufficiently stiff modulus of elasticity in order to prevent outward deflection of the cap  300  as it is tightened on the shaft  200 .  
         [0073]     The outer configuration of the shaft  200  incorporates a proximal tapered end that allows for advancement of the switch  160  from the back end and onto the controller  150 . The switch  160  may snap into position (engaging with means  260 ) when desired.  
         [0074]     An additional embodiment of the switch and connection system according to an aspect of the present invention may utilize a wireless system. In this wireless embodiment a transmitter within the switch is configured to transmit a signal to the power source or energizer  110  at the proximal end of the guidewire  1 . When the power source or energizer  110  receives the signal, a circuit is closed within the power source or energizer  110 , thereby allowing deflection to occur at the distal end of the guidewire  1 . This wireless embodiment may incorporate a small scale wireless device, such as (but not limited to) a Zigbee or Bluetooth wireless protocol system, which permits the system to be implemented within the design constraints of the switch and connection system.  
         [0075]     The various aspects of the present invention not only permit the use of a steerable or controllable guidewire having advantages over previous systems, but also allow the guidewire to be controlled at or near the point-of-access into the vasculature. The present invention also enables on-the-wire control while leaving the proximal end of the guidewire  1  to be selectably and easily freed to permit coaxial loading of other interventional radiology devices on the guidewire  1  ( e.g., catheters, angioplasty balloons and other devices).  
         [0076]     The various apparatuses and methods according to the present invention, and the principles that make them possible, may be applied in any fields requiring a steerable guidewire. Such fields include not only the vascular field of medicine, but also additional medical fields including, but not limited to, urology, general surgery and gynecology. Furthermore, these principles could also be applied to areas outside the medical field, such as veterinary medicine, inspection, mining, telecommunications (e.g., conduit), water distribution, security, national defense, electrical, entertainment and other systems.  
         [0077]     While the various aspects of the present invention have been shown and described with reference to particular embodiments, persons skilled in the art will understand that various changes in form and details may be made without departing from the spirit and scope of the invention as set forth in the appended claims. The many details and specifics should not be construed as limitations on the scope of the invention as claimed, but rather as exemplifications, and the scope of the invention should be determined not by these illustrated embodiment(s), but rather by the appended claims and their legal equivalents.
A controller for use with a guidewire, such as a vascular guidewire, provides a mechanism for gripping and applying a torque to the guidewire without the need to thread the guidewire axially through the controller and at a location close to a point of access of the guidewire. In one embodiment, the controller includes a side-access, multi-part assembly including a collet or other gripping element that applies a uniform radially inward force on the guidewire. In another embodiment, for use with guidewires having active electrically controllable elements, the controller integrally or removably incorporates a switch or other mechanism to initiate an energized state. The controller thereby permits ergonomic, single-handed control of an electronically steerable guidewire, including axially displacing, torquing and steering the guidewire.