Patent Publication Number: US-2010114114-A1

Title: Coronary vein navigator

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of and claims priority to U.S. patent application Ser. No. 12/348,746, filed Jan. 5, 2009, which is a continuation of U.S. patent application Ser. No. 10/226,647, filed Aug. 23, 2002. Each of the foregoing U.S. patent applications is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The invention relates generally to guide catheters, and, more particularly, to a coronary vein navigator catheter apparatus for accessing coronary vessels distal of the coronary sinus ostium. 
     BACKGROUND 
     Guiding catheters are instruments that allow a physician to locate and cannulate vessels in a patient&#39;s heart for performing various medical procedures, including venography and implanting of cardiac leads. Cannulating heart vessels requires navigating a small diameter, flexible guide through convoluted vasculature to access a destination heart vessel. Once the destination heart vessel is reached, the catheter acts as a conduit for insertion of payloads into the vessel. 
     A commonly accessed destination vessel for cardiac pacing lead insertion is the coronary sinus. A number of guiding catheter implementations have been developed for locating and accessing the ostium of the coronary sinus. In addition to the difficulties associated with accessing the coronary sinus, certain cardiac management devices, such as resynchronizers for example, require that the physician navigate a guiding catheter beyond the coronary sinus and into a coronary vein, such as the great cardiac vein, to facilitate lead implantation on the left ventricle. Guiding catheters that are well suited for accessing the coronary sinus may not be suitable for left-side coronary vein navigation. 
     By way of example, lateral and posterior branches of the coronary sinus and great cardiac vein often branch at acute, right or obtuse angles from a main vessel. To access such highly angled vessels, a guide wire is often used. However, the diameter of the main vessel can be very large in heart failure patients, for example. As such, the main vessel provides no back support for a guide wire to push off from when attempting to turn the guide wire into a side branch. 
     There is a need for an improved catheter apparatus and method of using same that can be used to efficiently navigate coronary vessels, particularly left-side coronary vessels. The present invention fulfills these and other needs, and addresses other deficiencies of prior art implementations and techniques. 
     SUMMARY 
     The present invention is directed to a system and method for navigating a catheter apparatus through coronary vasculature. According to one embodiment, a guide catheter system includes a guide catheter having a flexible shaft defining a longitudinal axis, a proximal end, a distal end, and a main lumen. The guide catheter system further includes a navigator catheter having a proximal end, a distal end, and a central lumen. The navigator catheter is longitudinally displaceable within the main lumen of the guide catheter. 
     The distal end of the navigator catheter is dimensioned for passage into an angled vein distal to a patient&#39;s coronary sinus ostium, and the central lumen is dimensioned to receive a longitudinally displaceable guide wire. A deflection arrangement is provided at the distal end of the navigator catheter for directing the guide wire into the angled vein. The deflection arrangement, which can be static or controllable, imparts a bend at the distal end of the navigator catheter having an angle sufficient to facilitate passage of the distal end of the navigator catheter into the angled vein. The bend angle can be an acute angle, a 90 degree angle or an obtuse angle relative to a longitudinal axis of the navigator catheter proximal of the deflection arrangement. 
     According to another embodiment of the present invention, a guide catheter system includes a guide catheter having a flexible shaft defining a longitudinal axis, a proximal end, a distal end, and a main lumen. A navigator member includes a proximal end and a distal end. The navigator member is longitudinally displaceable within the main lumen of the guide catheter, and the distal end of the navigator member is dimensioned for passage into an angled vein distal to a patient&#39;s coronary sinus ostium. A deflection arrangement is provided at the distal end of the navigator member. The deflection arrangement imparts a bend at the distal end of the navigator member having an angle sufficient to facilitate passage of the distal end of the navigator member into the angled vein. 
     In accordance with a further embodiment, a guide catheter system includes a guide catheter having a flexible shaft, a proximal end, a distal end, and a main lumen. A navigator catheter includes an outer wall having an aperture, a central lumen, a proximal end, and a distal end. The navigator catheter is longitudinally displaceable within the main lumen of the guide catheter. The distal end of the navigator catheter is dimensioned for passage into a cardiac vein distal to a patient&#39;s coronary sinus ostium. A deflection member is disposed within the central lumen of the navigator catheter proximate the aperture of the outer wall. The deflection member is oriented at an angle relative to a longitudinal axis of the navigator catheter sufficient to deflect a guide wire passed within the central lumen through the aperture of the outer wall of the navigator catheter and into an angled vein branching from the cardiac vein. 
     According to yet another embodiment of the present invention, a method of navigating coronary vasculature involves providing a guide catheter system which includes a guide catheter, a navigator catheter longitudinally displaceable within the guide catheter, and a deflection arrangement provided at a distal end of the navigator catheter. The method further involves advancing the guide catheter to at least a patient&#39;s coronary sinus ostium, and extending the navigator catheter from the guide catheter to a location proximate or within an angled vein distal to the coronary sinus ostium. Using the deflection arrangement, a guide wire passing through the navigation catheter is directed into the angled vein. A lead having an open lumen is advanced over the guide wire to direct the lead to an implant site within the angled vein. 
     In accordance with a further embodiment, a method of navigating coronary vasculature involves providing a guide catheter system which includes a guide catheter, a navigator catheter longitudinally displaceable within the guide catheter, and a deflection arrangement provided at a distal end of the navigator catheter. The method further involves advancing the guide catheter to at least a patient&#39;s coronary sinus ostium, and extending the navigator catheter from the guide catheter to a location proximate an angled vein distal to the coronary sinus ostium. The navigator catheter is seated within the angled vein. The guide catheter is passed over the navigator catheter to advance the guide catheter into the angled vein. The navigator catheter is retracted from the guide catheter, and a lead is advanced through the guide catheter to an implant site within the angled vein. 
     The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cut-away view of a patient&#39;s heart, showing a guide catheter apparatus embodying features of the present invention deployed within the heart; 
         FIGS. 2A-2D  illustrate embodiments of a guide catheter apparatus employing a navigator catheter having a pre-formed distal end; 
         FIGS. 3A and 3B  illustrate embodiments of a guide catheter apparatus employing a navigator catheter having a flexible, formable distal end; 
         FIG. 4  illustrates an embodiment of a guide catheter apparatus employing a guide catheter and a navigator catheter each having a pre-formed distal end; 
         FIGS. 5A and 5B  illustrate an embodiment of a guide catheter apparatus employing a navigator catheter having a steering or pulling arrangement for controllably changing a bend angle or shape of a distal region of the navigator catheter; 
         FIGS. 6A and 6B  illustrate an embodiment of a guide catheter apparatus employing a navigator catheter having an inflation mechanism for controllably changing a bend angle or shape of a distal region of the navigator catheter; 
         FIG. 7A  illustrates an embodiment of a guide catheter apparatus employing a navigator catheter having a deflection member for redirecting a guide wire through an exit aperture at a prescribed exit angle; 
         FIG. 7B  illustrates an embodiment of a guide catheter apparatus employing a navigator catheter having an adjustable deflection member for redirecting a guide wire through an exit aperture at a multiplicity of selectable exit angles; 
         FIG. 8  illustrates an embodiment of a guide catheter apparatus that includes a satellite lumen and incorporates the features of  FIG. 7B ; 
         FIGS. 9A and 9B  illustrate another embodiment of a guide catheter apparatus employing a navigator catheter having a controllable deflection member similar to that described in  7 B; 
         FIGS. 10A and 10B  illustrate another embodiment including a navigator catheter having a deflection member for redirecting a guide wire at a desired exit angle through an exit aperture of the navigator catheter; 
         FIGS. 11A and 11B  illustrate another embodiment including a navigator catheter having a deflection member for redirecting a guide wire at a desired exit angle through an exit aperture of the navigator catheter; and 
         FIGS. 12-14  illustrate an embodiment of a guide catheter apparatus employing a guide catheter and a navigator catheter that cooperate to access a left-side coronary vessel in accordance with the present invention. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail herein. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     In the following description of the illustrated embodiments, references are made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration, various embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without departing from the scope of the present invention. 
     A coronary vein guide catheter system of the present invention employs a navigator catheter or member in combination with a guide catheter to effectively navigate coronary vasculature having sharply angled vessels. As was discussed previously, it is often necessary to direct a guide wire to make a 90 degree or other sharp angled turn when attempting to reach a desired implant site, such as on the left ventricle. Traditional techniques for effecting sharp turns with a guide wire require close proximity between the guide wire and a vessel wall. Such techniques require contact between the guide wire and vessel wall to re-direct the guide wire in a direction needed to access a branch vessel. 
     In many circumstances, however, the primary vein from which the vein of interest branches is relatively large in comparison to the branch vein. For example, a sharply angled vein of interest may branch off of the coronary sinus or great cardiac vein. Because the diameter of the coronary sinus or great cardiac vein is many times larger than the diameter of the guide wire, the wall of the coronary sinus or great cardiac vein cannot effectively be used to assist in steering the guide wire into the branch vein. In such cases, a significant amount of time and skill is required on the part of the physician to successfully access such as a branch vein. 
     In accordance with one approach, a guide catheter system of the present invention employs a navigator catheter to advantageously direct a guide wire into a sharply angled branch vessel irrespective of the size of the primary vessel leading to the vessel vein. As such, the physician need not possess specialized navigation skills to efficiently navigate tortuous cardiac vasculature, such as left-side blood vessels. Employing a guide catheter system of the present invention provides for quicker navigation of difficult venous anatomy by the average skilled physician. 
     By way of example, and in accordance with one technique of the present invention, the guide catheter system is introduced into a patient&#39;s heart and advanced to pass into or through the coronary sinus. The navigator catheter or member is extended from the guide catheter and is positioned at a take off of a branch vein or is inserted into the take off of a branch vein distal to the coronary sinus ostium. A relatively small diameter guide wire (e.g., 0.018 inches) is then advanced into the branch vein through the navigator catheter, and the navigator catheter is then retracted. A coronary venous lead is then inserted over the proximal end of the guide wire and advanced to the target implant site. After lead implantation, the guide wire and guide catheter are retracted. 
     According to another technique of the present invention, a navigator catheter or member and guide catheter cooperate to access left-side coronary vasculature for implanting a lead in a manner which obviates the need for an over-the-wire lead implant technique. A navigator catheter or member is extended from the guide catheter situated within or distal to the coronary sinus to a position proximate a take off of a branch vein. The navigator catheter, which may have an open lumen or a closed lumen at its distal end, or the navigator member is maneuvered around the bend angle of the branch vein and advanced into the branch vein. In the case of an open lumen configuration, a relatively large diameter guide wire (e.g., 0.030-0.038 inches) can be advanced through the open lumen of the navigator catheter to assist in accessing the branch vein of interest. However, according to this embodiment, the guide wire is retracted after the navigator catheter is advanced into the branch vein of interest and not used as part of the lead implant procedure. 
     After the navigator catheter or member is seated in the coronary vein of interest, the guide catheter is then advanced over the navigator catheter or member so that the guide catheter is advanced past the bend angle of the destination vein and into the destination vein. The navigator catheter or member is then retracted from the guide catheter and a medical electrical lead is advanced through the guide catheter to the implant site. The lead is then implanted, and the guide catheter removed. It is to be understood that, although features of the present invention will generally be described with reference to veins of the heart, that such features are also applicable in the context of arteries of the heart, as well as other vessels of the body. 
     With reference to  FIG. 1 , a guide catheter system employing a guide navigator catheter is illustrated in accordance with an embodiment of the present invention. The guide catheter system  22  includes a navigator catheter  26  and a guide catheter  24 . The guide catheter system  22  is shown deployed within a patient&#39;s heart. As shown, the guide catheter system  22  is introduced into the patient&#39;s subclavian vein  30  and into the right atrium  32 . The physician uses the guide catheter system  22  to access the coronary sinus  34  via the right atrium  32 . A distal end of the guide catheter  24  and/or the navigator catheter  26  is used to locate and access the ostium of the coronary sinus  34 . 
     Having accessed the coronary sinus  34 , the navigator catheter  26  is advanced within the guide catheter  24  so that the distal end of the navigator catheter  26  extends beyond the distal end of the guide catheter  24 . The navigator catheter  26  employs a deflection arrangement to access a cardiac vein distal from the coronary sinus ostium. For example, a pre-shaped or shape-controlled distal end of the navigator catheter  26  is maneuvered into a vein that branches at a sharp angle from the coronary sinus or other cardiac vein, such as the great cardiac vein. After the navigator catheter  26  has been advanced into the branch vein, a guide wire  28  can be advanced through the guide and navigation catheters  24 ,  26  to a site  40  appropriate for lead implantation on the left ventricle. 
     Referring now to  FIG. 2B , an embodiment of a guide catheter system is shown embodying features of the present invention. A navigator catheter  54  is movably disposed within an open lumen of a guide catheter  52 , such that the navigator catheter  54  can translate longitudinally and, if desired, rotate axially within the guide catheter  52 . The navigator catheter  54  may include a proximal attachment to facilitate manipulation of the navigator catheter  54 . In the embodiment shown in  FIG. 4 , for example, the proximal attachment includes a wing luer  75 , although other suitable proximal mechanisms may be employed. In one configuration, the navigator catheter  54  includes an open lumen, and the open lumen can be adapted to receive a payload. In the context of a guide wire navigator embodiment, the open lumen of the navigator catheter  54  is dimensioned to receive a guide wire  56 . 
     As will be described hereinbelow, in other applications in which the navigator catheter  54  is employed to access a sharply angled coronary branch vein without use of a guide wire, the lumen of the navigator catheter  54  can be closed at its distal end. According to further applications, a navigator member  54 , such as a solid member as in the case of a stylet, is employed to facilitate access of sharply angled coronary branch veins, rather than use of a catheter. These and other implementations will be discussed hereinbelow. 
     The guide catheter  52  and navigator catheter  54  are configured with dimensions appropriate for the intended venous/arterial access path of a given medical procedure. For example, in the context of left-side cardiac access applications, the guide catheter  52  may be formed with an outer diameter from about 6 French to about 10 French, and have a length of about 40 cm to about 60 cm. The navigator catheter  54  may be formed with an outer diameter smaller than that of the guide catheter  52 , and may range from about 3 French to about 8 French and have a length longer than that of the guide catheter. In one configuration particularly useful in accessing coronary veins distal to the coronary sinus ostium, the navigator catheter  54  can have an outer diameter of about 6 French and the guide catheter  52  can have an outer diameter of about 8 French. It is understood that these exemplary dimensions are provided for purposes of illustration only, and not of limitation. 
     The guide catheter  52  and navigator catheter  54  are typically formed of a molded elastomeric tubing. An appropriate elastomeric material, such as a high durometer Pebax, urethane or epoxy, can provide the desired longitudinal stiffness. It is also possible to include an inner lubricious lining, formed from a material such as PTFE, or a lubricious coating, such as a hydrophilic coating, on an inner surface of the catheter tubing. The guide catheter  52  and navigator catheter  54  may also include a soft distal tip to prevent tissue abrasion along the venous pathways. 
     In other implementations, the guide catheter  52  and navigator catheter  54  can be constructed according to a multi-layer tube design. For example, one particular multi-layer tube design includes an inner lubricious liner, a braid  53 ,  55  (shown schematically in  FIG. 2D ), and an outer jacket. The lubricious liner is typically formed from a material such as PTFE and is disposed within an open lumen of the catheter shaft. The braid is typically located between the lubricious liner and outer jacket. The braid can provide longitudinal stiffness and requisite torque transmission to facilitate rotation and longitudinal advancement of the catheters  52 ,  54  through blood vessels, as well as helping to prevent kinking of the catheter shafts. The braid is usually constructed from a weave of stainless steel wire or ribbon, although a non-metallic fiber braid can also be employed, such as a braid formed to include polymer fibers (e.g., KEVLAR). The outer jacket is typically a high durometer polymer such as Pebax, urethane or epoxy, as previously discussed. The outer jacket provides the catheters  52 ,  54  with a smooth and durable outer surface. 
     In certain configurations, the guide catheter  52  can include a longitudinal pre-stress line, such as pre-stress line  151  shown in  FIG. 12 , that extends between the distal and proximal ends of the guide catheter  52 . The pre-stress line is typically a V-shaped notch or groove formed on a surface of the guide catheter  52 . Other configurations of a pre-stress line are possible, such as a fiber or wire longitudinally embedded within the guide catheter  52 . The pre-stress line provides for splitting of the guide catheter  52  to facilitate retraction of the guide catheter  52  from the patient. Two pre-stress lines can also be employed, the two pre-stress lines typically being distributed oppositely (180 degrees apart) around a transverse cross sectional perimeter of the guide catheter  52 . Inclusion of one or more pre-stress lines provides for peel-away retraction of the guide catheter  52  after lead implantation. 
     The splitting of the guide catheter  52  is beneficial as it allows the guide catheter  52  to be removed without the disturbing any attachments that may be mounted on the proximal end of navigator catheter  54 . For example, a wing luer  75  (best seen in  FIG. 4 ), may be mounted to the proximal end of the navigator catheter  54 . Splitting the guide catheter  52  during retraction enables the guide catheter  52  to be retracted without interfering with the wing luer  75 . 
       FIGS. 2A-2B  illustrate embodiments of a guide catheter system  50  which employ a navigator catheter  54  having a pre-formed shape  55  at a distal end of the navigator catheter  54 . In general terms, the profile and dimensions of the pre-shaped distal bend  55  are particular to the intended guiding application. The pre-shaped distal bend  55  can be thermoset on the flexible navigator catheter  54  during manufacture. 
     The pre-formed portion  55  of the distal end of the navigator catheter  54  is more compliant that the guide catheter  52 . As such, the pre-shaped distal bend  55  of the navigator catheter  54  tends to straighten when inserted into the guide catheter  52 , which facilitates advancement of the navigator catheter  54  through the guide catheter  52 . When the navigator catheter  54  is extended beyond the guide catheter  52 , the navigator catheter&#39;s distal end takes on the shape of the pre-formed curve imparted thereat. 
     In applications involving left-side coronary veins distal to the coronary sinus ostium, for example, the bend angle, α, can be selected to gain access to particular branch veins having sharp access angles.  FIGS. 2A-2C  show three configurations of a navigator catheter  54  having different bend angles, α.  FIG. 2A  depicts a navigator catheter  54  having a pre-formed distal bend  55  which forms an angle, α, of about 90 degrees relative to a longitudinal axis of the guide catheter  52  or the navigator catheter  54  proximal of the pre-formed distal bend  55 .  FIG. 2B  depicts a navigator catheter  54  having a pre-formed distal bend  55  which forms an obtuse angle, α, relative to the longitudinal axis of the guide catheter  52  or the navigator catheter  54  proximal of the pre-formed distal bend  55 .  FIG. 2C  depicts a navigator catheter  54  having a pre-formed distal bend  55  which forms an acute angle, α, relative to the longitudinal axis of the guide catheter  52  or the navigator catheter  54  proximal of the pre-formed distal bend  55 . In most applications, the bend angle, α, imparted at the distal end of the navigator catheter  54  can range from about 0 degrees to about 180 degrees or more. 
       FIGS. 3A and 3B  illustrate a coronary vein guide catheter system  60  according to another embodiment of the present invention. According to this embodiment, a navigator catheter  64  of the guide catheter system  60  includes a flexible distal end  65 . In this configuration, the distal end  65  does not include a pre-formed distal bend, as in the embodiments in  FIGS. 2A-2C . Rather, the flexible distal end region  65  is sufficiently flexible to assume the shape of the distal portion of a shaping member  66  when the shaping member  66  is advanced into and/or through the flexible distal end region  65 . 
     In typical use, the navigator catheter  64  is extended beyond the distal end of the guide catheter  62  and toward a coronary branching vein of interest. A shaping member  66 , such as a core guide wire or shaping wire, is advanced through the guide catheter  62  and navigator catheter  64 , and into or past the flexible distal end  65 . It is noted that the pre-formed distal end of the shaping member  66  can be more compliant than the guide catheter  62  and navigator catheter  64  to permit straightening thereto to facilitate advancement of the shaping member  66  though the catheters  62 ,  64 . The shape imparted to the flexible distal end  65  of the navigator catheter  64  facilitates locating and accessing of the branch vein of interest. 
     After the flexible end  65  is advanced a sufficient distance into the branch vein, the shaping member  66  is retracted. It is understood that a guide wire may be used with the navigator catheter  64  of this embodiment to enhance locating and accessing of the coronary vein of interest. In addition, the guide wire may be employed to facilitate over-the-wire implanting of a medical electrical lead in the subject coronary vein. Alternatively, a larger diameter guide wire can be used solely for coronary vein access, and not during lead implantation. 
     One particular advantage of this configuration is the ability to develop a multiplicity of acute and obtuse bend angles at the distal end of the navigator catheter by selective employment of shaping members  66  having different bend angles. As such, only the shaping member  66  need be retracted and substituted to modify the bend angle of the navigator catheter&#39;s distal end, thereby obviating the need to remove and substitute the navigator catheter itself to achieve this objective. 
       FIG. 4  illustrates an embodiment in which a navigator catheter  74  cooperates with a guide catheter  72  having a pre-formed distal end to enhance access to the coronary sinus and coronary veins distal to the coronary sinus ostium. A guide wire  76  may also be employed for catheter navigation and, if desired, lead implantation. In this embodiment, the distal end of the guide catheter  72  has a pre-shaped region  73  that can take on a variety of bend angles depending on a particular application. 
     The guide catheter system  70  is shown to include a guide catheter  72  having an open lumen and a pre-formed distal end  73 . A navigator catheter  74  having an open lumen and a pre-formed (e.g.,  FIGS. 2A-2C ) or formable (e.g.,  FIGS. 3A-3B ) distal end  75  is movably disposed within the open lumen of the guide catheter  72 . The shaped distal end  75  of the navigator catheter  74  is more flexible than the distal end  73  of the guide catheter  72 . The guide catheter system  70  further includes a proximal mechanism  75  used for axially rotating the guide catheter  72  relative to the navigator catheter  74  and longitudinally translating the navigator catheter  74  relative to the guide catheter  72 . The axial rotation and longitudinal translation allows the distal end section of the guide catheter system  70  to assume a selectable multiplicity of two- and three-dimensional shapes appropriate for accessing the coronary sinus and coronary vessel of interest distal to the coronary sinus ostium. Additional details concerning these and other enhancing features are described in commonly owned, co-pending applications identified under U.S. Ser. No. 10/059,809 filed Jan. 28, 2002, Ser. No. 10/105,087 filed Mar. 22, 2002, and Ser. No. 10/011,084 filed Dec. 6, 2001, each of which is hereby incorporated by reference herein in its respective entirety. 
     Turning now to  FIGS. 5A and 5B , there is shown an embodiment of a coronary vein guide catheter system  80  which includes a navigator catheter  84  having a deflection mechanism that provides for an adjustable bend angle and/or shape at the distal end of the navigator catheter  84 . The deflection mechanism can be controlled by the physician to control the shape of the distal end of the navigator catheter  84 . Bend angles of between 0 degrees and 180 degrees or more can be achieved to facilitate locating and navigation of cardiac structures and vessels of interest, such as the coronary sinus ostium and coronary vein and branch veins distal to the coronary sinus ostium. 
     According to one embodiment, the deflection mechanism of the guide catheter system  80  includes one or two steering tendons  86  that extend from the distal tip of the navigator catheter  84  and are accessible by the physician at the proximal end of the navigator catheter  84 . The steering tendons  86  are typically situated within respective satellite lumens. In general, the shape of the distal end of the navigator catheter  84  can be altered by applying tension to one or both steering tendons  86 . The navigator catheter  84  can be configured to be generally straight when no tension is applied to the tendons  86 , but may alternatively be fabricated to include a pre-formed shape at its distal end. 
     When steered, the distal end of the navigator catheter  84  can assume a variety of simple and complex shapes, including, for example, a semicircular arc or even a full circular shape whose radius of curvature depends upon the amount of tension applied to the steering tendon  86 . Employment of a shape altering deflection mechanism within the guide catheter system  80  provides for efficient coronary vein locating, accessing, and lead implantation. 
     In accordance with another embodiment, and with reference to  FIGS. 6A and 6B , the deflection mechanism employed in the guide catheter system  90  can include a hydraulic mechanism that controls the bend angle/shape of the distal end of the navigator catheter  94 . The navigation catheter  94  may be formed to include a pre-shaped distal bend. According to this embodiment, one or more inflation members  93  are situated at the distal end of the navigator catheter  94  to effect shape changes to the catheter&#39;s distal end. The inflation members  93  are in fluid communication with an inflation mechanism (not shown) situated at the proximal end of the navigator catheter  94  via inflation lumens  96 . Multiple inflation members  93  may be employed to effect more complex shapes and bend angles at the distal end of the navigation catheter  94 , in which case two or more inflation lumens  96  may be used. 
     The inflatable members  93  are in fluid connection with the inflation lumens  96 . The inflatable members  93  change a shape of the pre-shaped distal bend of the navigator catheter  94  upon inflation and deflation. The inflatable members  93  can be arranged to encompass a partial circumferential angle of a cross section of the navigation catheter  94 . The partial circumferential angle in this arrangement can range from about 90 degrees to about 190 degrees, for example. The inflation mechanism (not shown) selectably pressurizes and depressurizes the fluid within the inflation lumens  96  to respectively inflate and deflate the inflatable members  93 . 
     It is noted that, with respect to the various embodiments described herein, a central lumen of the navigator catheter  94  can be used to receive an injection of a contrast media for mapping blood vessels. The navigator catheter  94  or guiding catheter  92 , depending on the particular configuration, can thus be used to inject radiographic contrast media into the coronary sinus or other coronary vein to highlight the associated venous system. 
     In accordance with another embodiment of the present invention, and with reference to  FIGS. 7A and 7B , a coronary vein guide catheter system  100  employs a navigator catheter  104  which includes a deflection member  107  situated proximate an aperture  117  of a wall of the navigator catheter  104 . In general terms, the deflection member  107  is positioned within a central lumen of the navigator catheter  104  to contact a guide wire  106  being advanced through the navigator catheter  104 . Upon contact, the deflection member  107  redirects the path of the guide wire  106  so that the guide wire  106  exits the aperture  117  at a desired exit angle appropriate for a coronary branch vein of interest. 
     As shown, the deflection member  107  of  FIG. 7A  is fixedly mounted at a prescribed angle so that the guide wire  106 , upon contacting the deflection member  107 , is directed through the aperture  117  at a prescribed exit angle. In the illustration of  FIG. 7A , the deflection member  107  directs the guide wire  106  through the aperture  117  at an exit angle of about 90 degrees relative to a longitudinal axis of the navigation catheter  104 . It is understood that acute or obtuse exit angles can be achieved by judicious selection of the orientation of the deflection member  107  within the central lumen of the navigation catheter  104 . 
       FIG. 7B  illustrates a navigation catheter  104  employing an adjustable deflection member  107 . In this configuration, a pull wire  113  disposed in a satellite lumen  111  is employed to control the deflection orientation of the deflection member  107 . As shown, the deflection member  107  is pivotally mounted at a central axis  109  of the deflection member  107 . A bias mechanism, such as a spring mechanism, is employed to produce a force, F s , that opposes a proximally directed pull force on the pull wire  113 . As such, the deflection member  107  provides for an initial deflection orientation when no pull force is applied to the pull wire  113 . As shown, this initial deflection orientation results in a guide wire exit angle of about 90 degrees relative to a longitudinal axis of the navigation catheter  104 . It is understood that the initial deflection orientation of the deflection member  107  can be selected to provide for an initial acute or obtuse exit angle. 
     Application of a pull force on the pull wire  113  causes the deflection member  107  to rotate about its pivot axis  109 . As this pull force changes, the degree of deflection member rotation changes, thus providing for a concomitant change in the guide wire exit angle. It will be appreciated that a variety of guide wire exit angle ranges can be achieved by appropriate selection of deflection member size, positioning, initial deflection orientation, and range of rotation, among other considerations. 
       FIG. 8  illustrates a coronary vein guide catheter system  100  that incorporates the features shown in  FIG. 7B  and further includes a satellite lumen  115 . The satellite lumen  115  may be use for a variety of purposes, including accommodating a contrast media fluid, a sensor catheter or a shaping member, such as a stylet or shaping wire, for example. 
       FIGS. 9A and 9B  illustrate another configuration of a navigator catheter  104  that employs a controllable deflection member  107  similar to that described above with respect to  FIG. 7B . According to this implementation. The deflection member  107  has a length greater than the diameter of the navigator catheter&#39;s central lumen, such that it takes on a S-shape when biased in its initial deflection orientation, as is shown in  FIG. 9A . In this case, the deflection member  107  is orientated at an initial rotation angle, α 1 , relative to vertical axis  108 , which provides for a guide wire exit angle of θ 1  relative to horizontal axis  118 . 
     When a pull force is applied to the pull wire  113 , the deflection member  107  rotates, yet the opposing ends of the deflection member  107  advantageously maintain close contact with the guide catheter&#39;s inner walls. When fully rotated to orientation angle α 2 , the deflection member  107  shown in  FIG. 9B  provides for a guide wire exit angle of θ 2  relative to horizontal axis  118 . Continuous close contact between the deflection member  107  and walls of the navigator catheter&#39;s inner wall during deflection member movement improves the process of redirecting the path of the guide wire  106  into a sharply angled branch vein. 
       FIGS. 10A and 10B  illustrate another implementation of a navigator catheter  104  that employs a deflection member  120  for redirecting a guide wire  106  at a desired exit angle through an exit aperture  117  of the catheter  104 . According to this configuration, one end of the deflection member  120  is pivotally mounted at a mounting site on the inner wall of the navigator catheter&#39;s central lumen. The mounting site for the deflection member  120  is preferably immediately distal of the exit aperture  117 . Application of a proximally directed force, such as forces F 1  or F 2 , on the end of the deflection member  120  opposing the pivotally mounted end results in changing the deflection orientation of the deflection member  120 , and thus the exit angle of the guide wire. The control forces F 1  and F 2  can be generated through use of pull wires or other known means. 
       FIGS. 11A and 11B  illustrate yet another implementation of a navigator catheter  104  that employs a deflection member  120  for redirecting a guide wire  106  at a desired exit angle through an exit aperture  117  of the catheter  104 . In this configuration, one end of the deflection member  120  is pivotally mounted at a mounting site on the inner wall of the navigator catheter&#39;s central lumen as discussed above. An inflation member  122  is situated on the inner wall of the navigator catheter&#39;s central lumen at a location opposing the exit aperture  117 . The end of the deflection member  120  opposing the pivotally mounted end is in contact with the inflation member  122 . The inflation member  122  can be selectably pressurized and depressurized to achieve a desired guide wire exit angle. One or more inflation lumens (not shown) and a proximal inflation mechanism (not shown) of the type previously described may be employed to controllably pressurize and depressurize the inflation member  122 . 
       FIGS. 12-14  illustrate a further embodiment of the present invention. According to this embodiment, a coronary vein guide catheter system  150  includes a navigator catheter  154  movably extendable with respect to a guide catheter  152 . The navigator catheter  154  shown in  FIGS. 12-14  can be fabricated to include many of the previously described features, as can the guiding catheter  152 . For example, the guiding catheter  152  can include a pre-stress line  151  to facilitate peal-away retraction of the guide catheter  152  from the patient subsequent to lead implantation. 
     According to this embodiment, the navigator catheter  154  or navigator member (e.g., stylet) and guide catheter  152  are employed to access left-side coronary vasculature for implanting with or without use of a guide wire for over-the-wire lead implantation. The navigator catheter or member  152  is extended from the guide catheter  154 , which is shown situated within the coronary sinus  160 , to a position proximate a take off of a branch vein  162  distal to the coronary sinus ostium  160 . The navigator member or catheter  154 , which may have an open lumen or a closed lumen at its distal end, is maneuvered around the bend angle  163  of the branch vein  162  and advanced into the branch vein  162 . In the case of an open lumen configuration, a relatively large diameter guide wire (not shown) can be advanced through the open lumen of the navigator catheter  154  to assist in accessing the branch vein  162 . However, according to this embodiment, the guide wire is retracted after the navigator catheter  154  is advanced into the branch vein  162  and not used as part of the lead implant procedure. 
     After the navigator catheter or member  154  is seated in the coronary branch vein  162 , and as is best seen in  FIG. 13 , the guide catheter  152  is advanced over the navigator catheter or member  154  so that the guide catheter  152  is advanced past the bend angle  163  of the branch vein  162  and into the branch vein  162 . The navigator catheter or member  164  is then retracted from the guide catheter  152 , and a medical electrical lead  165  is advanced through the guide catheter  152 . The lead electrode  167  is then implanted at the implant site, and the guide catheter  152  is removed. 
     It will, of course, be understood that various modifications and additions can be made to the preferred embodiments discussed hereinabove without departing from the scope of the present invention. Accordingly, the scope of the present invention should not be limited by the particular embodiments described above, but should be defined only by the claims set forth below and equivalents thereof.