Abstract:
Methods for utilizing a device for blocking (e.g., embolizing) the side branches of an anatomical passageway under endoscopic guidance. The device comprises an elongate catheter body having a side branch blocking apparatus, such as an embolization catheter, disposed therein and further incorporating an endoscope (e.g., an angioscope). The incorporated endoscope is useable to a) visually locate side branches which emanate from the anatomical passageway and b) visually observe the operation of the side branch blocking apparatus. Disclosed are methods for performing in situ embolization of the side branches of a vein, under angioscopic visualization. The endoscopic component of the device may also be utilized to visually observe the use and/or effect of one or more separate device, such as valvulotome(s) used for cutting venous valves located within the lumen of a vein.

Description:
RELATED APPLICATIONS 
     This is a continuation of application Ser. No. 08/910,944, filed Aug. 8, 1997, now U.S. Pat. No. 5,947,994 which is a continuation of application Ser. No. 08/486,038, filed on Jun. 7, 1995, now U.S. Pat. No. 5,707,389. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     This invention relates generally to medical devices and methods, and more particularly to a method for performing endoluminal embolization of the side branches of a tubular anatomical passageway such as a blood vessel. 
     2. Description of the Related Art 
     In clinical medicine, it is sometimes desirable to selectively block certain blood vessels or anatomical passageways of the body. For example, the selective blockage of blood vessels may be utilized as a means of a) creating localized hemostasis to treat or prevent hemorrhage; b) blocking blood flow through an aneurysmic region of an artery; c) blocking the blood supply to a tumor; and d) closing off the side branches of a blood vessel segment which is to be subsequently utilized as a graft for replacing or bypassing an occluded artery. 
     One particular type of surgical procedure wherein a segment of vein is utilized to bypass a blocked artery is known as an in situ vein bypass procedure. Such in situ vein bypass procedure are often used as a means of treating patients in whom a leg artery (e.g., the femoral artery or the popliteal artery) has become occluded due to atherosclerotic disease. In these procedures, a vein which runs generally parallel to the occluded artery is prepared by a) transecting the vein at locations above and below the arterial blockage, b) inserting a valvulotome device into the lumen of the vein segment to disrupt or lyse all venous valves located therewithin, and c) blocking all side branches of the vein segment. Thereafter, the ends of the vein segment are anastomosed to the blocked artery, at locations above and below the blockage, thereby forming a bypass conduit around the arterial blockage. 
     In the past, the methods used for blocking the side branches of the vein segment for later use in an in situ bypass procedure required either a) surgical exposure and dissection of an entire vein segment to locate and ligate all of the side branches which emanate therefrom, or b) the use of angiographic radiological techniques to locate the vein side branches so that small individual incisions could be made to access and ligate each side branch. These prior art side branch blocking procedures were, however, associated with numerous problems. For example, the open surgical exposure and dissection of the entire vein segment resulted in a sizable incision, with accompanying potential for wound infection and post operative discomfort. Alternatively, the use of angiographic radiological techniques for location of the side branches resulted in substantial radiation exposure of the patient, and required the injection of contrast media into the vein to facilitate fluoroscopic visualization of the side branches. 
     More recently, efforts have been undertaken to develop simplified endovascular techniques whereby the side branches of the vein segment may be directly visualized by way of an angioscope inserted into the vein and an endovascular embolization catheter may be utilized to perform endoluminal embolization of the side branches, without requiring surgical exposure of the side branches or the injection of radiographic contrast fluid. 
     The use of these endovascular embolization catheters under direct angioscopic visualization has typically required that a separate angioscope be utilized for the purpose of a) visually locating the venous side branches and b) visually observing and guiding the endovascular side branch embolization procedure. 
     The manipulation and use of an angioscope which is separate from the embolization catheter has proven to be problematic. In particular, it is difficult to maintain proper positioning of the angioscope so as to a) carefully locate all venous side branches within the vein segment and b) properly visualize and observe the endovascular side branch embolization procedure. Also, these procedures typically require that the separate angioscope be inserted in a direction which is retrograde to, or opposite, the direction in which the embolization catheter is inserted. This results in a less than optimal vantage point for visualizing the side branches because the normal anatomical angle of the side branches is obtuse to the direction in which the embolization catheter is inserted, thereby resulting in the luminal openings into the side branches being angled away from the vantage point provided by an angioscope which has been inserted in the opposite direction. 
     Thus, there exists a need in the art for the development of an improved endovascular side branch blocking device (e.g., an embolization catheter) which incorporates an integrated angioscope which is usable to a) clearly locate venous side branches from a vantage point located on the device, as the device is advanced through the lumen of the vein segment and b) visually observe and verify the blocking of each side branch by use of the side branch blocking device (e.g., embolization catheter). 
     SUMMARY OF THE INVENTION 
     The present invention provides a method and device for performing endoluminal embolization of the side branches of an anatomical passageway (e.g., a blood vessel) under endoscopic (e.g., angioscopic) visualization. The device of the present invention comprises a) an elongate, flexible catheter body having first and second lumens extending longitudinally therethrough; b) a side opening formed in the catheter body near the distal end thereof, said side opening being communicative with the second lumen of the catheter body; c) an embolization device disposed within the second lumen of the catheter body and operative to pass at least one embolization member out of the side opening of the catheter body; and d) an endoscope (e.g., an angioscope) disposed within the first lumen of the catheter body, and moveable back and forth between i) a distally advanced position whereat the endoscope is positioned to provide viewing of an area ahead of the distal end of the catheter body; and, ii) a proximally retracted position whereat the endoscope is positioned to provide viewing of the side opening of the catheter body (without obstructing passage of an embolization member out of the side opening). 
     In accordance with the method of the present invention, the device of the forgoing character may be operated such that the endoscope (e.g., angioscope) of the device is initially positioned in its distally advanced position to permit viewing and location of side branches that emanate from an anatomical passageway as the catheter body is being advanced, distal end first, through the anatomical passageway; and, thereafter the endoscope may be subsequently retracted to its proximally retracted position to permit viewing of the passage of an embolization member out of the side opening and into a side branch of the anatomical passageway. 
     Further objects and advantages of the invention will become apparent to those skilled in the art upon reading and understanding of the following detailed description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is perspective view of one embodiment of the device of the present invention. 
     FIG. 2 a  is an enlarged perspective view of the distal end of the device of FIG. 1, with the angioscopic component of the device positioned in its distally advanced position. 
     FIG. 2 b  is an enlarged perspective view of the device of FIG. 1, with the angioscopic component of the device in its proximally retracted position. 
     FIG. 2 c  is an enlarged, rear, perspective view of an insert member which forms a portion of the distal end of the device of FIG.  1 . 
     FIG. 3 a  is a longitudinal sectional view of the distal end of the device of FIG. 1 with the angioscopic component of the device positioned in its distally advanced position. 
     FIG. 3 b  is a longitudinal sectional view of the distal end of the device of FIG. 1 with the angioscopic component of the device in its proximally retracted position. 
     FIG. 4 is an enlarged elevational view of the proximal assembly portion of the device of FIG.  1 . 
     FIG. 4 a  is an enlarged longitudinal sectional view of segment  4   a  of FIG.  4 . 
     FIG. 5 is a longitudinal sectional view through line  5 — 5  of FIG.  4 . 
     FIGS. 6 a - 6   e  are a step-wise showing of a method whereby the device of the present invention is utilized to effect endoluminal embolization of the side branch of a blood vessel, under angioscopic guidance and visualization. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following detailed description and the accompanying drawings are provided for purposes of describing and illustrating presently preferred embodiments of the invention only, and are not intended to limit the scope of the invention in any way. 
     i. The Preferred Device 
     With reference to the accompanying figures, a preferred device  10  of the present invention comprises an elongate, flexible catheter body  12  having a proximal end PE and a distal end DE. The catheter body  12  comprises a dual lumen tube having a first lumen  14  and a second lumen  16  extending longitudinally therethrough. A distal tip member  18  is attached to the distal end of the dual-lumen tube, as shown. The distal tip member  18  comprises a rigid, generally cylindrical member having a distal portion DP of a first diameter and a proximal tubular member  36  of a smaller second diameter. The proximal tubular member  36  of the distal tip member  18  is inserted into and secured to the dual-lumen tube such that the distal tip member  18  forms the distal end of the catheter body  12 . The distal tip member  18  includes a first luminal trough  20  which, when properly positioned, is in alignment with the first lumen  14  of the catheter body  12 . Also, the distal tip member  18  comprises a second lumenal passageway  22  which, when properly positioned, is in alignment with the second lumen  16  of the catheter body  12 . The distal face  24  of the distal tip member  18  is substantially closed, except for a generally U-shaped angioscopic view port  26  formed at the distal end of the first lumenal trough  20 . In the preferred embodiment, the generally U-shaped angioscopic view port  26  has a tapered or chamfered edge, as shown. 
     With reference to FIG. 3 a , a bulkhead  28  exists between the first lumen  14  and the second lumen  16  of the catheter body  12 . Such bulkhead  28  terminates a spaced distance proximal to the distal face  24  of the distal tip member  18 . A generally U-shaped angioscope supporting ledge  30  is formed immediately proximal to the angioscope view port  26  formed in the distal face  24  of the distal tip member  18 . Such angioscope supporting ledge  30  is in alignment with the generally U-shaped floor of the first lumenal trough  20 . A side opening  32  exists within the distal tip member  18 , proximal to the distal end surface  24  and distal to the distal most extent of the bulkhead  28 , as shown in FIG. 3 b . A curved or angular deflection surface  34  is formed in the interior of the distal tip member  18 , between the distal end of the second luminal passageway  22  and the side opening  32  of the distal tip member  18 . In the embodiment shown, the deflection surface  34  is of a radiused or curved configuration. It will be appreciated however, that such deflection surface  34  may be in the form of an angular bend or any other shape which will deflect the advancing distal tip member  18  out of the side opening  32 . A rigid sleeve member  36  is fixedly mounted within the proximal portion of the second lumenal passageway of the distal tip member  18 , and extends partially into the distal portion DP thereof, as shown. This rigid sleeve member  36  inserts into the second lumen  16  of the catheter body  12 , beneath bulkhead  28 , and serves as a guide for a distal tubular portion  40  of an embolization device  42  which is disposed within the second lumen  16  of the catheter body  12 . 
     With reference to FIGS. 3 b  and  5 , the embolization device  42  comprises an elongate pliable embolization catheter body  44  having the distal tubular member  40  extending from the distal end thereof A resilient embolization coil  46  is disposed within the lumen of the embolization catheter body  44  and or distal tubular member  40 . Such embolization coil  46  is positioned ahead of a push wire  48 , said push wire  48  being disposed within the lumen of the catheter body  44 . 
     With reference to FIGS. 1 and 4, proximal Y-connector  50  is positioned on the proximal end of the catheter body  12 . The proximal Y-connector  50  comprises a main body portion  52  and a side arm  54 . An extension tube  56  and embolization device plunger barrel  58  extend out of the side arm  54  of the proximal Y-connector  50 . As seen in FIGS. 4 a  and  5 , the catheter body  44  and push wire  48  extend through the side arm  54  of the Y-connector  50 , through the tubular extension  56  and into the interior of a plunger member  60  which is disposed within the barrel member  58 . An abutment member  62  having a generally conical distal surface is affixed to the outer surface of the catheter body  44 . First and second telescoping tube members  45 ,  49  are disposed within the interior of the plunger  60 . The push wire  48  extends through the first telescoping tube member  45 , and into the lumen of the second telescoping tube member  49 , and is affixed thereto. The proximal end of the second telescoping tube member  49  is affixed in contact with the proximal end of the plunger  60 , as shown in FIG.  5 . 
     A longitudinal rigid abutment projection  70  extends into the interior of the barrel  58 , and incorporates a generally conical depression  72  in the proximal end thereof. As the plunger  60  is forced in a distal direction, the generally conical distal surface of the abutment member  62  will abut against the generally conical depression of the abutment projection  70 , and the generally cylindrical wall of the plunger  60  will enter the generally annular space  74  which surrounds the abutment projection  70 . This allows the body of the plunger  60  to continue forward in the distal direction, while the abutment member  62 , which is affixed to the outer surface of the catheter body  44 , is unable to travel further in the distal direction due to its abutment against the abutment projection  70 . 
     As will be described in greater detail below with respect to FIGS. 6 a - 6   e , the initial movement of the plunger  60  in the forward direction, will cause the entire catheter body  44  to move forward such that the distal tubular member  40  will slidably advance through the sleeve  36 , and will impinge against the radiused deflection surface  34  of the distal tip member  18 . Further advancement of the plunger  60  will cause the distal tubular member  40  to be directed out of the side opening  32  of the distal tip member, by the radiused abutment surface  34 , such that the distal portion of the distal tubular member  40  protrudes outwardly from the catheter body  12 , in a direction substantially perpendicular to the longitudinal axis LA of the catheter body  12 . Thereafter, continued pressure against the plunger  60  will cause the cylindrical body of the plunger  60  to continue forward within the annular space  74 , thereby forcing the push wire  48  to advance through the catheter body  44 . Such distal advancement of the push wire  48  propels the embolization coil  46  through the distal tubular member  40  and out of the distal end thereof. 
     After the embolization coil  46  has been expelled out of the distal end of the distal tubular member  40 , the plunger  60  may be withdrawn in the proximal direction, thereby withdrawing the catheter body  44  and distal tubular member  40 , fully into the second lumen  16  of the catheter body  12 . The entire plunger  60 , catheter body  44  and push wire  48  may be fully extracted and replaced by another replacement unit comprising another plunger  60 , catheter body  44  and push wire  48 , with yet another embolization coil  46  preloaded into the embolization catheter  44  as described hereabove and shown in FIGS. 3 a  and  3   b . An ovoid window  76  (FIG. 5) is formed in the body of the barrel  58  to permit the operator to observe the advancement of the catheter body  44  and conical abutment member  62  as the plunger  60  is being depressed during the embolization coil deployment procedure. Referring to the distal end DE of the scope body  82 , as seen in FIG. 2 a , one or more illumination outlet ports  85  may also be provided to illuminate the visual field of the scope  80 . Alternatively, the illumination outlet ports  85  and image receiving port  84  may be incorporated into a single port or lens surface whereby illuminating light is cast out of the distal end of the scope body  82  and an optical image is concurrently received therein. The illumination outlet ports  85  are connected to one or more bundles of illumination fibers which extend longitudinally through the scope body  82 . Similarly, the optical image inlet port  84  comprises a lens or other communication means which is connected to one or more optical image transmitting fibers which extend longitudinally through the scope body  82 . As seen in FIG. 1, the scope body  82  extends through the main body portion  52  of the proximal connector assembly  50 , and is connected to a scope adjustment/control assembly  86 . A handpiece portion  88  and proximal scope connector assembly  90  extend proximally from the scope adjustment/control assembly  86 . The proximal connector assembly  90  incorporates a light source connector  92  whereby a light source may be connected to the illumination fiber(s) of the scope so as to pass illuminating light in the proximal direction through the scope body  82  and out of the illumination ports  82  on the distal end thereof Also, the proximal scope connector assembly  90  incorporates a camera connector  94  whereby a camera, eye piece, video monitor, video tape recorder and/or other video viewing devices may be connected to the optical image fibers of the scope  90  so as to electronically process and permit viewing of an optical image received through image receiving port  84 . 
     As shown in the details of FIGS. 4 and 4 a , the scope adjustment/control assembly  86  incorporates a fine adjustment mechanism  100  for precisely adjusting the longitudinal positioning of the scope  80  relative to the catheter body  12  of the device so as to eliminate any unwanted protrusion or malpositioning of the scope  80  due to variations in the tolerances or sizing of the scope  80  relative to the catheter body  12  of the device. Also, the scope adjustment/control assembly  86  incorporates a scope advancement/retraction mechanism  102  whereby the operator may volitionally move the scope  80  between its distally advanced position (FIGS. 2 a ,  3   a ) and its distally retracted position (FIGS. 2 b ,  3   b ). 
     The fine longitudinal adjustment mechanism  100  of the adjustment/control assembly  86  comprises a rotatable nut  106  disposed on the proximal end of the main body portion  52  of the Y-connector assembly  50 . The rotatable nut  106  has an internally threaded passageway  108  extending longitudinally therethrough. The scope body  82  extends through the main body portion  52  of the proximal Y-connector assembly  50 , and through the threaded inner passageway  108  of the rotatable nut  106 . An externally threaded member  112  engages the internal threads of the rotatable nut  106 . Rotation of the nut  106  in a first direction will cause the externally threaded member  112  and scope body  82  to advance in the distal direction, while opposite rotation of the nut  106  in the opposite direction will cause the externally threaded member  112  and scope body  82  to retract in the proximal direction. In this regard, rotatable nut  106  may be utilized to effect fine adjustment of the longitudinal positioning of the scope body  82  relative to the remainder of the device  10 . Such fine adjustment may be accomplished to ensure that the distal end DE of the scope body  82  is properly positioned within the view port  26  prior to insertion of the device  10 , thereby eliminating any improper scope positioning which could result from variability in the sizing or manufacturing tolerance of the scope devices  80  relative to the remainder of the device  10 . 
     Further, with specific reference to FIGS. 4 and 4 a , the scope advancement/retraction mechanism  102  comprises a generally cylindrical outer member  120  having a plurality of annular ribs  122  formed on the outer surface thereof to prevent slippage of the operators fingers as the annular member  120  is advanced and/or retracted. Engagement member  124  is firmly affixed to the scope body  82  and to the surrounding inner surface of the cylindrical member  120 . An annular spring member  130  is positioned within an annular notch formed about the outer surface of engagement member  124 , and a series of corresponding engagement notches or detents  131  are formed in the inner surface of the cylindrical member  120 . Thus, cylindrical member  120 , engagement member  124 , scope body  82  and proximal scope connector assembly  90  may be concurrently moved back and forth, longitudinally, relative to the catheter body  12 , proximal Y-connector assembly  50 , fine adjustment mechanism  100 , and handpiece  88 . As such longitudinal movement is accomplished, the spring member  130  will engage the individual detents  131  to bias and hold the scope body  82  in selected longitudinal positions. In this regard, the operator may manually grasp and move the cylindrical member  120  to accomplish movement of the scope  80  between its distally advanced position (FIGS. 2 a ,  3   a ) wherein the illumination outlet ports  86  and imaging receiving port  84  of the scope  80  are positioned immediately adjacent, or within, the image receiving port  126  formed in the distal face  24  of the distal tip member  18 , and the proximally retracted position (FIGS. 2 b ,  3   b ) wherein the illumination ports  86  and image receiving port  36  of the scope  80  are positioned immediately proximal to the side opening  32  formed in the distal tip member  18 . 
     In this regard, when the scope  80  is in its distally advanced position (FIGS. 2 a ,  3   a ) the scope  80  may be utilized to visualize an area which is ahead of, and surrounding, the distal end DE of the catheter body  12 , thereby facilitating advancement of the catheter body  12  through a blood vessel and location of any side branches of the blood vessel which are to be embolized and occluded. After the side branch of a vessel has been located, the scope  80  is withdrawn to its proximally retracted position (FIGS. 2 b ,  3   b ), whereby the scope  80  may be utilized to ensure that the radiused deflection surface  34  of the distal tip member  18  is positioned immediately adjacent the side branch into which the embolization coil  46  is to be ejected. 
     Thereafter, the scope  80  may continue to be utilized as the plunger  60  of the embolization catheter device  42  is depressed into the barrel  58 , thereby causing the embolization catheter  44 , including its distal tube member  40  to advance in the distal direction, being deflected by the radiused deflection surface  34  out of the side opening  32  and into the adjacently positioned side branch of the blood vessel. Thereafter, the scope  80  may continue to be utilized to view the passage of the embolization coil  46  through the distal tubular member  40  of the embolization catheter  44  and into the adjacent side branch. Thereafter, the scope  80  may continue to be utilized to view the retraction of the distal tube member  40  of the embolization catheter  44  into the second lumen  16  of the catheter body  12 . 
     Thus, the longitudinal moveability of the scope  80  between its distally advanced position (FIGS. 2 a ,  3   a ) and its proximally retracted position (FIGS. 2 b ,  3   b ) permits the scope body  82  to be easily utilized for both the advancement and positioning of the catheter body  12  of the device  10 , and the subsequent deployment of the embolization catheter device  42  into the intended side branch and ejection of the embolization coil  46  thereinto. 
     ii. The Preferred Method 
     FIGS. 6 a - 6   e  provide a step-by-step illustration of a preferred method of utilizing the device  10  to perform an endovascular side branch occlusion procedure under angioscopic guidance. 
     Generally, FIGS. 6 a - 6   e  show a blood vessel BV having a lumen L 1 . A side branch SB having a side branch lumen L 2  emanates from the blood vessel BV, as shown. Also, for purposes of illustration, a venous valve VV is shown in a typical position within the lumen L 1  of blood vessel BV. 
     Prior to insertion of the device  10 , the operator will manually ensure that cylindrical member  120  is in its fully distally advanced position and, thereafter, will manually rotate fine adjustment nut  106  to make certain that the distal end of the scope body  82  is properly positioned relative to the distal end surface  24  of the device  10 . After such visual inspection and preparation of the device  10 , the device is inserted and utilized as shown in FIGS. 6 a - 6   e , and described herebelow. 
     FIG. 6 a  shows an initial step in the method wherein the catheter body  12  of the device  10  has been inserted into the patient&#39;s vasculature and has been advanced transluminally into the segment of blood vessel BV wherein the side branch occlusion procedure is to be performed. The scope advancement/retraction mechanism  102  of the device  10  is manually advanced to its distal-most position, thereby causing the scope  80  to assume its distally advanced position wherein the distal end of the scope body  82  is positioned within the scope view port  26  formed in the distal face  24  of the distal tip member  18 . When in such position the scope  80  provides a field of view which is ahead of the distal end DE of the device  10 , as denoted by the shaded area in FIG. 6 a . Thus, when so positioned, the scope  80  may be utilized to discern the presence and location of the side branch SB, and to facilitate the proper positioning of the side opening  32  of the device  10  next to the side branch SB of the blood vessel BV such that an embolization coil  46  may be volitionally passed into the side branch SB using the embolization device  42  carried within the catheter body  12 . As shown in FIG. 6 b , the scope advancement/retraction mechanism  102  is then moved to its proximal-most position, thereby retracting the endoscope  80  to its proximally retracted position. When in its proximally retracted position, the scope  80  provides a field of view which includes the ostium of the side branch SB, the side opening  32  of the device  10 , and a portion of the radius deflection surface  34  which serves to guide the passage of the distal tubular member  40  of the embolization device  42  into the side branch SB. In this regard, the endoscope  80  is utilized to visually determine the proper positioning of the catheter body  12  relative to the side branch SB, such that the radiused deflection surface  34  is in alignment with the lumen L 2  of the side branch SB so as to deflect the distal tubular member  40  of the embolization device  42  into the lumen L 2  of the side branch SB. 
     As shown in FIG. 6 c , after the distal end DE of the catheter body  12  has been properly positioned, the plunger  60  is advanced into the barrel  58  of the embolization device  42 , thereby causing the distal tubular member  40  to advance in the distal direction, and to be deflected by radiused deflection surface  34  into the lumen L 2  of the side branch SB. 
     As shown in FIG. 6 d , further advancement of the plunger  60  into the barrel  58  of the embolization device  42  causes the push wire  48  to advance in the distal direction, thereby pushing the embolization coil  46  through the lumen of the embolization catheter body  44 , out of the distal end of the distal tubular member  40  and into the lumen L 2  of the side branch SB. As the embolization coil  46  passes out of the distal end of the distal tubular member  40 , the embolization coil  46  resiliently assumes a tightly wound helical or other mass configuration, thereby forming an occlusion or blockage within the lumen L 2  of the side branch SB. After the embolization coil  46  has been fully deployed into the lumen L 2  of the side branch SB, the plunger  60  is withdrawn in the proximal direction, thereby retracting the embolization catheter body  44  in the proximal direction, and causing the distal tubular member  40  thereof to again become fully retracted into the second lumen  16  of the catheter body  12  of the device  10 . Thereafter, the scope  80  may again be returned to its distally advanced position, and the catheter body  12  may be further advanced to the site of another side branch whereat the above-described side branch occlusion procedure is repeated. 
     As shown in FIG. 6 e , after all of the side branches SB have been occluded, the device  10  is removed from the blood vessel. The embolization coil  46  remains within the lumen L 2  of each side branch SB, as shown. 
     It will be appreciated that, when the scope  80  is in its distally advanced position, the angioscope  80  may be utilized to visually observe and guide the operation of a separate instrument located ahead of the distal end DE of the catheter body  12 . For example, the scope  80  may be positioned in its distally advanced position and utilized to visually observe and guide the use of a separate endovascular valvulotome device for lysing the venous valves VV which are endogenous to the lumen LI of the blood vessel BV. 
     Any suitable type of valvulotome device may be utilized to cut the venous valves VV concurrently or in conjunction with the performance of the side branch blocking procedure of the present invention, under visualization by the scope  80  incorporated in the device of the present invention. One example of a valvulotome device which is usable in conjunction with the present invention is the device described in the U.S. Pat. No. 5,658,302 entitled METHOD AND DEVICE FOR ENDOLUMINAL DISRUPTION OF VENOUS VALVES (Wicherski et al), issued Aug. 19, 1997. 
     To facilitate angioscopic visualization of the device  10  of the present invention during its use, it will be appreciated that a clear liquid such as 0.9% NaCl or Ringer&#39;s lactate solution may be introduced into the lumen L of the blood vessel BV in a manner which displaces blood from the lumen L and provides an optically transparent environment for visualization by the scope  80 . Such solution(s) may be infused through an introducer sheath which surrounds the device  10 , particularly in cases where the device  10  has been inserted percutaneously. Alternatively, when a valvulotome device has been inserted in the retrograde or opposite direction, and is being used separately in conjunction with the device  10  of the present invention, the desired liquid may be infused through a liquid infusion lumen of the valvulotome device. 
     Alternatively, a separate irrigation catheter may be inserted into the vein and utilized to infuse the desired liquid into the lumen L of the blood vessel BV. 
     As another alternative, a separate fluid infusion lumen may be formed within the device  10  of the present invention, and may be coupled to an optional additional fluid infusion side arm  97  such that the desired liquid may be infused directly through the device  10  of the present invention, without the need for infusion of liquid through a separate introducer, catheter, valvulotome or other apparatus. 
     In summary, it is to be appreciated that the invention has been described herein with reference to certain presently preferred embodiments of the invention. Various changes, alterations, additions, and deletions may be made to the above-described preferred embodiments without departing from the intended spirit and scope of the present invention. Accordingly, it is intended that all such changes, alterations, deletions and modifications be encompassed within the scope of the following claims.