US20030181938A1 - Transluminal devices, systems and methods for enlarging interstitial penetration tracts - Google Patents

Abstract

Methods, apparatus and systems for enlarging interstitial penetration tracts which have been formed between blood vessels or elsewhere within the body of a mammalian patient. Included are debulking-type tract enlarging systems, dilation-type tract enlarging systems, tissue-slicing-type tract enlarging systems and two-catheter-type tract enlarging systems.

Description

FIELD OF THE INVENTION
• The present invention relates generally to medical devices and methods, and more specifically to transluminal devices, systems and methods which are useable to enlarge interstitial tracts (e.g., man made puncture tracts or small passageways) which extend between two (2) anatomical conduits (e.g., blood vessels) or otherwise through tissue(s) within a mammalian body.[0001]
BACKGROUND OF THE INVENTION
• Applicant has devised several new medical procedures wherein passageway-forming catheters are advanced into anatomical conduits (e.g., blood vessels) and are used to create one or more interstitial passageways which extend outwardly, from the conduit in which the catheter is positioned, to another conduit or anatomical structure. Some of these procedures may be used to form flow-through passageways between the anatomical conduit (e.g., blood vessel) in which the passageway-forming catheter is positioned, and another anatomical conduit (e.g., another blood vessel) or a different location on the same anatomical conduit (e.g., a downstream site on the same blood vessel). Alternatively, these procedures may be used to form access passageways between the anatomical conduit (e.g., blood vessel, urethra, fallopian tube, etc..) and another anatomical structure (e.g., a tumor, organ, muscle, nerve, etc.).[0002]
• In at least some of applicant's procedures, the interstitial passageway(s) are initially formed by advancing a tissue-penetrating element (e.g., a small diameter needle or a flow of tissue-penetrating energy) from the passageway-forming catheter, through the wall of the anatomical conduit in which the catheter is positioned, and into the target location. In some cases, the interstitial passageway which is formed by the initial passage of the tissue-penetration element from the passageway-forming catheter is of relatively small diameter—and must subsequently be enlarged (e.g., debulked, dilated, expanded, stretched) to accommodate the desired flow of biological fluid (e.g., blood) or passage of other substances/ devices therethrough.[0003]
• In particular, as described in applicant's earlier-filed U.S. patent applications Ser. No. 08/730,327 and 08/730,496, such enlargement of the initially formed interstitial passageway (e.g., penetration tract) may be particularly important when the procedure is being performed to by-pass an obstruction within a coronary artery. For example, in some of applicant's procedures, a primary interstitial passageway is formed between an obstructed coronary artery and an adjacent coronary vein, such that blood will flow from the obstructed artery into the adjacent coronary vein. In such applications, the arterial blood which enters the adjacent coronary vein through the primary interstitial passageway is allowed to retroperfuse the ischemic myocardium by retrograde flow through the coronary vein. In other of applicant's procedures, one or more secondary interstitial passageways are formed between the coronary vein into which the arterial blood has flowed and the obstructed artery (or some other coronary artery) to allow arterial blood which has entered the coronary vein to reenter the obstructed artery (or some other coronary artery), after having bypassed the arterial obstruction. Thus, in either of these interventional procedures, it is important that the primary and/or secondary interstitial passageway(s) remain patent and sufficiently large in diameter to support the continued flow of arterial blood to the myocardium. However, the task of enlarging the small diameter interstitial passageway(s) (e.g., puncture tracts) formed by the initial passage of the tissue-penetrating element presents numerous technical challenges.[0004]
• Although the prior art has included a number of catheter-based devices which may be used to enlarge or remove obstructive matter from the lumen of a blood vessel or other anatomical conduit (e.g., a blood vessel). These devices include; atherectomy catheters, embolectomy catheters, balloon angioplasty catheters, laser ablation catheters, etc. However, these prior art lumen-enlarging/lumen-clearing devices have typically not been intended for use in small diameter puncture tracts which diverge at an angle from the conduit lumen in which the catheter is located, as is typically the case in applicant's above-summarized interventional procedures.[0005]
• Accordingly, there exists a need for the design and development of a new device, system and method for enlarging interstitial penetration tracts (e.g., man-made punctures or small passageways) which extend between adjacent anatomical conduits (e.g., blood vessels) within a mammalian body.[0006]
SUMMARY OF THE INVENTION
• The present invention provides devices which are useable in combination with each other (i.e., as a system) to enlarge an interstitial tract (e.g., a small diameter penetration tract through tissue) which extends from a blood vessel or other anatomical conduit of the body. The devices and systems of the present invention generally fall into three (3) major classifications—1) debulking-type tract enlargement systems, 2) dilating-type tract-enlargement systems, and 3) slicing-type tract enlargement systems.[0007]
• In accordance with the invention, one debulking-type tract enlargement system (referred to herein as an “advancable” debulker) generally comprises: a) an elongate, pliable, tubular sheath sized for insertion into the lumen of an anatomical conduit from which the interstitial tract extends, said sheath having a lumen which extends longitudinally therethrough; b) a counter-traction member which is advanceable, i.) through the lumen of the tubular sheath and ii.) at least partially through the interstitial tract, such that the countertraction member engages or becomes positioned in relation to tissue which lies adjacent the interstitial tract to thereafter exert proximally-directed force upon such tissue; and, c) a debulker (e.g., a tissue removing apparatus or flow of energy) which is advanceable out of the lumen of the sheath in a distal direction (i.e., substantially opposite the proximally-directed force being exerted by the counter-traction member) to remove tissue from the area adjacent the tract.[0008]
• Further in accordance with the invention, there is provided another debulking-type tract enlargement system (referred to herein as a “retractable” debulker) generally comprises: a) an elongate, pliable, tubular sheath sized for insertion into the lumen of an anatomical conduit from which the interstitial tract extends, said sheath having a lumen which extends longitudinally therethrough, and b) a pull-back debulker (e.g., a tissue-removing apparatus or flow of energy) which is i.) initially advanceable out of the lumen of the sheath in a distal direction so as to pass through the penetration tract which is to be enlarged, and ii.) thereafter retractable in the proximal direction so as to remove tissue which lies adjacent the interstitial tract, thereby enlarging the interstitial tract.[0009]
• Still further in accordance with the invention, there is provided a dilating-type tract enlargement system (referred to herein as a “dilating” system) which generally comprises: a) an elongate, pliable, tubular sheath sized for insertion into the lumen of an anatomical conduit from which the interstitial tract extends, said sheath having a lumen which extends longitudinally therethrough, and b) a dilator (e.g., an elongate member) having at least one tissue-dilating member (e.g., a tapered, frusto-conical member, balloon or radially deployable member(s)) formed thereon, such dilator being advanceable into the penetration tract which is to be enlarged, and is subsequently useable to dilate such penetration tract, thereby resulting in the desired enlargement thereof. A positioning surface may be formed on the dilator to abut against tissue which lies adjacent the passageway in a manner which will enable the operator to determine that the dilator has been advanced to its desired position and is properly located to allow the dilate the interstitial tract as desired.[0010]
• Still further in accordance with the invention, there is provided a slicing-type tract enlargement system (referred to herein as a “tissue-slicing” system) which generally comprises a) an elongate shaft which is advanceable through the interstitial tract, and b) at least one tissue slicing member which extends or is extendable from the shaft to incise or cut tissue which lies adjacent the interstitial tract as the shaft is advanced and/or retracted through the tract. In some embodiments, the tissue slicing member(s) may be initially disposed in a radially compact configuration which is flush with, or only slightly protrusive beyond, the outer surface of the shaft, thereby allowing the shaft to be advanced through the interstitial tract without cutting or disrupting the surrounding tissue. Thereafter, the tissue slicing member(s) is/are shifted to a radially expanded configuration wherein such tissue-slicing member(s) extend or protrude laterally from the shaft so as to slice, incise or cut at least some of the tissue which surrounds the tract. The tissue-slicing member(s) need not be concentric about the shaft, but rather may be of substantially flat configuration so as to create a defined incision or cut in the tissue. Moreover, the tissue-slicing member(s) may be configured so as not to completely sever and remove tissue in the manner of the above-sumarized debulking-type embodiment, but rather may simply form a slit or incision adjacent the tract such that the surrounding tissue will continuously or intermittantly separate to allow flow of fluid (e.g., blood) therethrough.[0011]
• Still further in accordance with the invention, there is provided a two-catheter type tract enlarging system (referred to herein as a “two-catheter” system) which is specifically useable to enlarge an interstitial tract or passageway which has been formed between two adjacent anatomical conduits (e.g., blood vessels). Such two-catheter system generally comprises a) a first catheter having a tract-enlarging apparatus (e.g., a debulker, dialtor or tissue-slicing member of the above-described nature) which is advancable from an opening at or near the distal end of that catheter, and b) a second catheter which has an anvil member (e.g., an abuttable surface or receiving cavity) which is sized and configured to correspond with the leading end of the tract-enlarging apparatus of the first catheter. The first catheter is positioned in one of the anatomical conduits, and the second catheter is positioned in the other anatomical conduit, with its anvil member located next to the interstitial tract or passageway which is to be enlarged. Thereafter, the tract enlarging apparatus is advanced through the tract or passageway until it registers with (e.g., abutts against or is received with) the anvil member of the second catheter. As the tract enlarging apparatus is being advanced, the anvil member serves to provide counterforce against the tissue adjacent the initially formed tract or passageway so as to prevent unwanted protrusion or “tenting” of the tissue into the second anatomical conduit, and to ensure efficient cutting of the tissue in cases where a debulking or tissue slicing type tract enlarging apparatus is used.[0012]
• Still further in accordance with the invention, either the debulking-type, dilating type, tissue-slicing type or two catheter type tract enlargement systems of the present invention may incorporate a guidewire lumen which extends longitudinally through the i.) tract enlarging member (e.g., debulker, dilator or tissue slicing member) to permit the tract enlarging member to be advanced over a small guidewire which has previously been passed through the penetration tract which is to be enlarged. Thus, the provision of such guidewire lumen may permit the system to be used to dilate penetration tracts which are of extremely small diameter, or which have become substantially closed off due to constriction of the surrounding tissue, provided that a guidewire was previously inserted through such penetration tract.[0013]
• Still further in accordance with the invention, energy such as radio-frequency energy or electrical resistance heat may be applied to the tract enlarging member (e.g., debulker, dilator, or tissue slicing member) to enhance the tract-enlarging efficiency thereof.[0014]
• Still further objects and advantages of the present invention will become apparent to those of skill in the relevant art, upon reading and understanding of the following detailed description of the invention and the accompanying drawings.[0015]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of a debulking-type tract enlarging system of the present invention.[0016]
• FIG. 2 is a schematic perspective view of a human body having the tract enlarging system of FIG. 1 operatively inserted into the coronary vasculature.[0017]
• FIG. 2[0018]ais an enlarged, cut-away view of segment2a-2aof FIG. 2.
• FIG. 3 is an enlarged sectional view through line[0019]3-3 of FIG. 2a.
• FIGS. 3[0020]a-3dare step-wise showings of a presently preferred method for using the tract enlarging system of FIG. 1 to debulk and enlarge an interstitial penetration tract which has been created between a coronary artery and an adjacent coronary vein.
• FIG. 4 is an enlarged, side elevational view of the distal portion of the tract enlarging system of FIG. 1.[0021]
• FIG. 4[0022]ais a cross sectional view through line4a-4aof FIG. 4.
• FIG. 4[0023]bis a cross sectional view through line4b-4bof FIG. 4.
• FIG. 4[0024]cis a cross sectional view throughline4c-4cof FIG. 4.
• FIG. 5[0025]ais a side elevational view of the distal portion of the tract enlarging system of FIG. 1 disposed in a retracted configuration.
• FIG. 5[0026]bis a side elevational view of the distal portion of the tract enlarging system of FIG. 1 disposed in a retracted configuration.
• FIG. 6 is a is a longitudinal sectional view of the distal portion of the subselective sheath component of the system of FIG. 1.[0027]
• FIG. 7 is a is a longitudinal sectional view of the distal portion of the tissue cutter component of the system of FIG. 1.[0028]
• FIG. 7[0029]ais an exploded, longitudinal sectional view of the distal potion of the tissue cutter of FIG. 7.
• FIG. 8 is a side elevational view of the counter-traction member component of the system of FIG. 1.[0030]
• FIG. 8[0031]ais an exploded, longitudinal sectional view of the distal potion of the counter-traction member of FIG. 8
• FIG. 9[0032]ashows a first alternative counter-traction member having a tissueengaging member formed of radially expandable members, wherein the radially expandable members are in their collapsed configuration.
• FIG. 9[0033]bshows the first alternative counter-traction member of FIG. 9a, with its radially expandable members in a partially expanded configuration.
• FIG. 9[0034]cshows the first alternative counter-traction member of FIG. 9a, with its radially expandable members in their fully expanded configuration.
• FIG. 10[0035]ais a side elevational view of a debulking-type tract enlarging system which is equipped with a first type of an energy emitting debulker (e.g., a radio-frequency system).
• FIG. 10[0036]bis an enlarged perspective view in the distal end of the energy-emitting debulker of FIG. 10.
• FIG. 10[0037]cis a cross sectional view through line10c-10cof FIG. 10a.
• FIG. 10[0038]dis a side elevational view of the distal portion of an another alternative debulking-type system which comprises an energy-emitting debulker in conjunction with an energy emitting counter-traction member, and wherein the energy emitting counter-traction member is in a retracted position.
• FIG. 10[0039]eshows the system of FIG. 10 c with its energy-emitting countertraction member in its extended position.
• FIG. 10[0040]fis a cross sectional view throughline10e-10eof FIG. 10d.
• FIG. 10[0041]gis a side elevational view of the distal portion of another energy-emitting debulker which incorporates an annular array of laser-transmitting optical fibers.
• FIG. 10[0042]g′ is a distal end view of the debulker of FIG. 10g.
• FIG. 10[0043]his a side elevational view of the distal portion of another energy-emitting debulker which incorporates a central laser-transmitting optical fiber (or fiber bundle) in combination with a prism which disseminates the laser light in an annular array to effect the desired severing or vaporization of tissue.
• FIG. 11[0044]ashows a debulking-type tract enlarging system having an advanceable debulker and a second alternative counter-traction member having a tissue-engaging member formed of an inflatable balloon, wherein the inflatable balloon is in its non-inflated, collapsed configuration.
• FIG. 11[0045]bis a cross sectional view through line11b-11bof FIG. 11a.
• FIG. 11[0046]cshows the second alternative counter-traction member of FIG. 11a, with its balloon in a fully inflated, expanded configuration.
• FIG. 11[0047]dshows the second alternative countertraction member of FIG. 11a, with its balloon in its fully inflated, expanded configuration and the shaft fully retracted into the lumen of the debulker.
• FIG. 11[0048]eshows a debulking-type tract enlarging system having an advanceable debulker and a third alternative counter-traction member which comprises a plurality of outwardly splayable tissue-engaging members, wherein the tissue-engaging members are in there radially collapsed configuration and the counter-traction member is only slightly advanced out of the debulker.
• FIG. 11[0049]fshows the system of FIG. 11ewherein the tissue-engaging members are in their radially expanded configuration and the counter-traction member is being further advanced out of the debulker.
• FIG. 11[0050]gshows the system of FIG. 11fwherein the tissue-engaging members are in their radially expanded configuration and the counter-traction member is fully advanced out of the debulker.
• FIG. 11[0051]hshows the system of FIG. 119 wherein the tissue-engaging members are in their radially expanded configuration and the counter-traction member has been fully retracted such that the distal end of the debulker engages the interior of the expanded tissue-engaging members.
• FIG. 12[0052]ais a side elevational view of the distal portion of a retractable debulking-type tract enlarging system of the present invention, wherein the retractable debulker is disposed in a distally extended position.
• FIG. 12[0053]bis a view of the system of FIG. 12A, wherein the debulker is disposed in a partially retracted position.
• FIG. 13 is a side elevational view of a dilation-type tract enlarging system of the present invention, disposed with its dilator (i.e. balloon) in a stowed (i.e., deflated) position.[0054]
• FIG. 13[0055]ais view of the system of FIG. 13, disposed with its dilator (i.e., balloon) in an operative (i.e., inflated) position.
• FIG. 13[0056]bis a cross sectional view throughline13b-13bof FIG. 13. FIG. 13cis a cross sectional view through line13c-13cof FIG. 13.
• FIG. 14 is a graphic illustration of a continuous emission of radiofrequency energy in accordance with the present invention.[0057]
• FIG. 15 is a graphic illustration of intermittant or pulsed emission of radiofrequency energy in accordance with the present invention.[0058]
• FIG. 16 is a longitudinal sectional view of the distal portion of a debulker of the present invention which incorporates an apparatus for controlling the pressure appplied by the debulker and/or for signifying when the debulking procedure is complete.[0059]
• FIG. 17 is a side elevational view of the distal portion of a tissue-cutting type of tract enlarging system of the present invention.[0060]
• FIG. 18[0061]ais a side elevational view of an alternative tissue-cutting tip for the system of FIG. 17.
• FIG. 18[0062]bis a top plan view of the alternative tissue-cutting tip of FIG. 18a.
• FIG. 18[0063]cis a distal end view of the alternative tissue cutting tip of FIG. 18a.
• FIG. 19 is a schematic showing of two adjacent blood vessels having a penetration tract formed therebetween, and a two-catheter tract enlarging system of the present invention operatively disposed therein to enlarge the penetration tract.[0064]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The preferred embodiments and examples described in the following paragraphs, and shown in the accompanying drawings, should be considered as exemplars, rather than limitations on the devices, systems and methods of the present invention.[0065]
• The particular embodiments described in detail below include debulking-type[0066]tract enlargeing systems10 and10a, dilating-typetract enlargement systems10b, and tissue-slicing-type tract enlarging systems10c.
• A. Debulking-Type Systems[0067]
• Generally, the debulking-[0068]type systems10,10aserve to remove (e.g., cut, sever, ablate, vaporize, etc.) tissue which surrounds or lies adjacent to the initially formed interstitial tract thereby enlarging the tract. The description set forth in the following paragraphs includes a distally advanceable debulking-type system10 as well as a proximally retractable debulking-type system10a.
• 1. Advanceable Debulking-type Systems[0069]
• FIGS.[0070]1-9 show a preferred, distally-advanceable debulking-typetract enlargeing system10 which is useable to enlarge a penetration tract. As shown in detail in FIGS.4-8a, this distallyadvanceable debulking system10 generally comprises a) asubselective sheath12, b) a distally-advanceable debulker14 which is passable out of the subselective sheath, in a distal direction DD, and acounter-traction member16 which is advanceable through the penetration tract ahead of thedebulker14, and engageable with tissue adjacent the tract to exert a counter-force (i.e. a force directed in the proximal direction PD) upon the tissue which is to be severed by thedistally advancing debulker14. It is also to be understood that thecounter-traction member16 may simily be positioned adjacenyt the tissue such that it does not actually exert force against the tissue until thedebulker14 is advanced into contact with the tissue, at which time the tissue will then be compressed between the debulker and thecounter-traction member16 as the debulking procedure is performed.
Subselective Sheath
• The[0071]subselective sheath12 of the embodiment shown in the drawings comprises a flexible tube which is sized to be advanceable into the anatomical conduit from which the interstitial penetration tract extends. With particular reference to the showings of FIG. 4,4cand6, thepreferred subselective sheath12 comprisesinner wall30 preferably formed of formed of polytetrafluoroethylene (PTFE), anouter wall32 preferably formed of polyether block amide polymer (e.g., Pebax™), and abraid34 captured between inner30 and outer32 walls,such braid34 terminating distally at a location which is approximately 2-10 mm from the distal end of thesheath12. In this manner, there is defined a non-braideddistal portion36 of approximately 2-10 mm and a braidedproximal portion38. The presence of thebraid34 within theproximal portion38 of thesheath12 enhances its strength and resistance to crimping or kinking, while the non-braideddistal portion36 of thesheath12 remains soft and pliable to avoid injury or damage to the walls of blood vessels or other tissues, as thesheath12 is advanced. For use in coronary blood vessels, thesheath12 will preferably have an outer diameter of 0.050-0.150 inch and an inner lumen diameter of 0.040-0.140 inch.
• In some embodiments, the[0072]subselective sheath12 may have lumen which curves laterally and exits through an outlet port formed in the sidewall of thesheath12. Such side outlet sheath (not shown) may be advanced to a position where the side outlet aperture is in direct alignment with the penetration tract PT which is to be enlarged. Thereafter, thedebulker14 may be advanced out of the side outlet aperture and directly through tissue which surrounds the penetration tract PT.
Advanceable Debulker
• The[0073]debulker14 of the embodiment shown in the drawings comprises a rotating tissue cutter which, when advanced in the distal direction and concurrently rotated, will sever and remove a cylindrical mass of tissue which surrounds the penetration tract. With particular reference to the showings of FIGS. 7 and 7a, thispreferred debulker14 comprises aflexible tube40 which has alumen44 extending longitudinally therethrough, and anannular cutting member42 mounted on the distal end thereof. Theannular cutting member42 has a sharpened leadingedge46 and ahollow bore48 which extends therethrough. The cuttingmember42 is mounted securely on the distal end of the tube, preferably such that thebore46 of theannular cutting member42 is in direct axial alignment with thelumen44 of thetube40, and the outer surface of the cuttingmember42 is flush with the outer surface of thetube40. Thetube40 is preferably formed of a flexible plastic such as polyether block amide polymer (e.g., Pebax™) and thecutter member42 is preferably formed of a rigid material such as stainless steel. In embodiments intended for use in coronary blood vessels, thisdebulker14 will preferably have an outer diameter of 0.05-0.13 inches and an inner (lumen) diameter of 0.04-0.12 inches. A plurality of bearingmembers50 may be mounted at spaced-apart locations within thelumen44 of thedebulker14 to facilitate rotation of the debulker41 about a central shaft (e.g., theshaft60 of the countertraction member16). A drive motor/handpeice22 may be mounted on the proximal end of thedebulker14, as shown in FIGS. 1 and 7. This drive motor/handpeice22, when actuated, will rotationally drive thedebulker14, at a suitable rate of rotation to facilitate the desired severing of tissue. In applications where thedebulker14 is being used to sever soft tissue, it is preferable that the motor/handpeice22 be capable of driving thedebulker14 at 60-300 revolutions per minute. One example of a commercially available drive motor/handpeice22 which may be used is the MDV Motor Drive Unit manufactured by DVI , Inc.
Counter-traction Member
• The[0074]counter-traction member16 of the embodiment shown in the drawings serves to pass through the interstitial tract to be enlarged, ahead of the debulker, and prevents unwanted protrusion or “tenting” of the tissue into the adjacent anatomical conduit, thereby enhancing the tissue cutting efficience of the debulker. With particular reference to the showings of FIGS. 4, 4a,8 and8a, thepreferred counter-traction member16 comprises an elongate,pliable shaft60 having a dilator/tissue-engagingmember62 mounted on the distal end thereof, and aguidewire lumen67 . The tract dilator/tissue engaging member62 comprises afrustoconical body68 and a cutting-engagement plate64 formed on the proximal end thereof. Theproximal surface66 of the cutting-engagement plate64 is disposed in a plane P which is substantially perpendicular to the longitudinal axis LA of theshaft60. The frustoconical portion is preferably formed of soft plastic such as polyether block amide polymer (e.g., Pebax™) and the cutting/engagement plate64 is preferably formed of hard material such as polycarbonate or stainless steel. As shown in the exploded view of FIG. 8a, acavity73 may be formed in the proximal end of the dilator/engagement plate62, including ashaft receiving portion74 and anannular groove70. Thedistal portion65 of the cutter/engagement plate64 is inserted intocavity73 such that anannular shoulder72 formed about theproximal portion65 will frictionally engage a correspondingannular groove70 formed about the interior of thecavity73, thereby holding the cutting/engagement plate64 in fixed position on the distal end of the dilator/engagement member62. The distal end of theshaft60 is then inserted through thebore67 of the cutting/engagement plate64 until it bottoms out in theshaft receiving portion74 of thecavity73. An adhesive or thermal compression bonding may be used to securely hold the shaft in contact with the dilator/engagement member62. Additionally or alternatively, theproximal portion65 of the cutting/engagement plate64 may act as a ferrule, exerting radial inward pressure against the shaft to frictionally hold the shaft in its inserted position within the cavity. Thecounter-traction member16 also acts to protect the adjacent vessel or luminal anatomical structure from iatrogenic trauma (e.g., perforation, laceration) as the debulker is advanced.
• It is to be appreciated that various other types of tissue-engaging members may be utilized in addition to, or as an alternative to the[0075]particular counter-traction member16 shown in FIGS.1-8. Some examples of alternative types ofcountertraction members16a,16b,16care shown in FIGS. 9a-9cand11a-11h.
• With reference to FIGS. 9[0076]a-9cone alternative counter-traction member16acomprises atelescoping shaft80 formed of adistal shaft portion80′ and aproximal shaft portion80″, having a plurality of radiallyexpandable members82 disposed about theshaft80, as shown. Preferably, a guidewire lumen (not shown) extends longitudinally through theshaft80. Each radiallyexpandable member82 has a distal end which is affixed to thedistal shaft portion80′ and a proximal end which is affixed to theproximal shaft portion80″. As shown in FIG. 9a, when thedistal shaft portion80′ is fully advanced in the distal direction, the radially expandable members will be in a radially collapsed configuration of diameter D, which is sufficiently small to be advanceable through the previously formed penetration tract. Thereafter, as shown in FIGS. 9band9c, thedistal shaft portion80′ may be retracted into theproximal shaft portion80″ to cause the radially expandable members to bow or expand outwardly. Thus, when thedistal shaft portion80′ is partially retracted the radiallyexpandable members82 may assume a partially expanded configuration of diameter D₂when thedistal shaft member80′ is fully retracted the radiallyexpandable members82 will assume a fully expanded configuration of diameter D₃.
• Referring to FIGS. 11[0077]a-11d, anotheralternative counter-traction member16bcomprises anelongate shaft90 which has aguidewire lumen92 and a balloon inflation/deflation lumen94 extending therethrough, and aballoon96 mounted thereon. With the balloon in its deflated state as shown in FIG. 1 Oa, theshaft90 is advanceable over a gudewire and through the penetration tract PT which is to be enlarged. After theballoon96 has emerged out of the opposite end of the penetration tract PT, inflation fluid is injected through the inflation/deflation lumen94 to inflate theballoon96 as shown in FIG. 10c. As described in more detail herebelow, theinflated balloon96 will the abut against and engage the tissue which surrounds the penetration tract PT, and will exert proximally directed force on such tissue while thedebulker14 is advanced through the tissue. As shown in FIG. 1 Od, after the tissue has been fully severed, theshaft90 will be fully retracted into thelumen44 of thedebulker14 and the cuttingsurface46 of theannular cutting member42 will abut against a reinforcedregion98 of the balloon. Such reinforcedregion98 is sufficiently resistant to cutting or puncture to prevent theannular cutting member42 from bursting or penetrating through the wall of theballoon96. Referring to FIGS. 11e-11h, there is shown yet another counter-traction member16cwhich comprises anelongate shaft150 having a plurality of resilient or spring loaded, outwardlysplayable members160 which are attached at their distal ends to theshaft150. The proximal ends of thesplayable members160 are biased to a radially expanded configuration as shown in figures11f-11h, but are initially compressible to a radially compact configuration wherein they may be receieved within thelumen44 of the debulker, as shown in FIG. 11e. Initially, with thesplayable members160 are placed in their radially compact configuration and retracted at least partially within thelumen44 of thetubular member40 of thedebulker14. After the system has been inserted in the body and positioned adjacent the interstitial tract to be enlarged, theshaft150 is advanced in the distal direction to drive thesplayable members160 through the interstitial tract. As the proximal ends of the splayable members emerge from the distal end of the interstitial tract, they will spring outwardly to their radially expanded configuration and will engage the tissue adjacent the distal end of the tract. Thereafter, proximally directed pressure may be applied to the shaft as thedebulker40 is advanced in the distal direction. This resultss in the desired counter-traction on the tissue being severed by theannular cutting member42. At it end of the tract enlarging procedure, the leadingedge46 of theannular cutting member42 will be nested within and in contact with thesplayable members160, as shown in FIG. 11h. In this manner, as will be more fully appreciated after reading the explanation of the detailed operation of the device set forth herebelow, the tissue which has been severed from the area surrounding the interstitial tract will be received within thelumen44 of the debulker, for subsequent removal from the body.
Operation of the Distally Advanceable Debulking-type System
• Prior to operation, the[0078]system10 is assembled in the manner shown in FIG. 5a, such that theshaft60 of thecounter-traction member16 is slidably and rotatably disposed within thelumen44 of the debulker14 (i.e. extending through thebearings50 located within thelumen44 of the debulker14) and thecountertraction member16 anddebulker14 are positioned within thelumen31 of thesheath12. Thissystem10 may then be utilized to enlarge a small penetration tract PT which has been formed between an anatomical conduit and some other anatomical conduit or cavity within the body. For purposes of illustrating and explaining the operation of the present invention, FIGS. 3a-3dshow a specific coronary revascularization procedure wherein an interstitial passageway is to be formed between a coronary vein CV and an adjacent coronary artery CA, to permit arterial blood to flow into the coronary vein CV.
• With reference to FIGS. 3[0079]a-3d, after an interstitial penetration tract PT has been formed between a coronary artery CA and coronary vein CV, a small guidewire GW is passed through such penetration tract PT. The guidewire GW is passed, proximal end first, into the distal end of theguidewire lumen67 which extends through thecounter-traction member16. With thedebulker14 andcountertraction member16 disposed within thelumen31 of thesubselective sheath12, thesystem10 is advanced over the guidewire GW until the distal end of thesubselective sheath12 becomes positioned within the coronary vein CV at a location approximately 0.10 inch (i.e., 2-3 mm) from the penetration tract PT. Thereafter, as shown in FIG. 3, the counter-traction member is further advanced such that the dilator/engagement member62 will pass through the penetration tract PT and into the coronary artery CA. As the dilator/engagement member emerges into the lumen of the coronary artery CA the tissue surrounding the penetration tract PT will elastically retract about the distal portion of the shaft and theproximal surface66 of the cutting/engagement plate64 will abut against the coronary artery wall immediately adjacent the opening of the penetration tract PT into the coronary artery CA. Thereafter, proximally directed pressure is applied to thecounter-traction member16 while concurrently advancing thedebulker14 in the distal direction, as shown in FIG. 3a. As the advancingdebulker14 comes into contact with the tissue which surrounds the penetration tract PT, the drive motor/handpeice22 is actuated so as to rotate the debulker at approximately 60-300 RPM. As shown in FIG. 3b, this causes the sharpened leadingedge46 of the cuttingmember42 to cut a cylindrical bolus of tissue as the rotatingdebulker14 continues to advance. The application of proximally directed pressure on thecounter-traction member16 concurrently with the distally directed advancement of thedebulker14 prevents the surrounding tissue from “tenting” and enhances the cutting efficiency of thedebulker14. Also, because the tissue which is being severed is located directly behind the cutting/engagement plate64, the severed bolus of tissue will be prevented from escaping into the coronary artery CA, and will be forced into the lumen of thedebulker14 whereby it may be extricated and removed from the body along with thedebulker14, as illustrated in FIG. 3c. This results in the formation of an enlarged bloodflow passageway EBP, as desired.
• As shown in FIG. 3[0080]d, and in accordance with applicants methodology described in earlier-filed U.S. patent applications Ser. No. 08/730,327 and 08/730,496, one or more embolic blockers B or other flow-blocking means may be utilized to prevent arterial blood which enters the coronary vein CV through the enlarged bloodflow passageway EBP from flowing in the venous return direction, and to cause such arterial blood to flow through the coronary vein CV in the retrograde direction, thereby bypassing the obstruction OB located in the adjacent coronary artery CA.
• 2. Retractable Debulking-type Systems[0081]
• FIGS. 12[0082]a-12bshow an example of a retractable debulking-typetract enlargement system10a, of the present invention. Thissystem10acomprises aproximal counter-force member112 in combination with aretractable debulker14a, as shown in FIGS. 12aand12b.
Proximal Counter-force Member
• The[0083]proximal counter-force member112 comprises a tube having a lumen (not shown) which extends longitudinally therethrough and an annular cutting/engagement plate100 formed on the distal end thereof. The annular cutting/engagement plate100 serves to engage a pull-back tissue cutter formed on the proximal end of theretractable debulker14a. In embodiments where the retractable debulker is rotatable, a plurality ofbearings50 of the type described hereabove may be coaxially disposed at spaced apart locations within the lumen of theproximal counter-force member112.
Retractable Debulker
• The[0084]retractable debulker14aof this embodiment comprises ashaft102 having a flexible frusto-conical dilator104 formed thereon, and anannular cutter member106 mounted on the proximal end of thedilator104, as shown. The frusto-conical dilator104 may be constructed and configured the same as thefrustoconical body68 described hereabove. Theannular cutting memebr106 may be constructed and configured the same as theannular cutting member42 of the first embodiment described hereabove. Thisannular cutting member106 has a sharpenedproximal edge108 which will sever tissue when retracted therethrough. A guidewire lumen(not shown) extends longitudinally through theshaft102 and through the frusto-conical dilator. Optionally, the retractable debulker14amay be rotatably driven by a drive motor/handpeice22 as described hereabove.
Operation of the Retractable Debulker Type System
• Prior to operation, this retractable debulking type system[0085]1 Oa is assembled such thatshaft100 theretractable debulker14ais slidably and (and in some cases rotatably) disposed within the lumen of theproximal counter-force member112. In embodiments wherein the debulker14ais rotatable, theshaft102 will extend through anybearings50 disposed within the lumen of thecounter-force member112. Theshaft102 may initially be retracted such that the proximal sharpenededge108 of theannular cutter106 is in abutment with theannular cutting plate100. The counter-force member112 andretractable debulker14aare positioned within thelumen31 of asubselective sheath12 as described hereabove. This system1 Oa may then be utilized to enlarge a small penetration tract PT which has been formed through the sidewall of and extending outwardly from an anatomical conduit of the body, and through which a guidewire has been inserted.
• The guidewire GW which extends through the penetration tract is inserted into the distal end of the guidewire lumen (not shown) of the[0086]retractable debulker14a. Thesubselective sheath12 having thecounterforce member112 and retractable debulker positioned therewith, is maneuvered into the anatomical conduit from which the penetration tract extends. Thereafter, theshaft102 of theretractable debulker14ais advanced such that thedilator104 is forced through the penetration tract. After the sharpenedproximal edge108 of theretractable debulker14ahas emerged out of the opposite end of the penetration tract, the tissue which surrounds the penetration tract will elastically constrict about the shaft. Thecounter-force member112 is then advanced until the distalannular cutting plate100 is in abutment with the wall of the portion of the wail of the anatomical conduit which surrounds the proximal end of the penetration tract.
• Thereafter, distally directed counter-force is applied to the[0087]counter-force member112 while theretractable debulker14ais retracted in the proximal direction. Optionally, theretractable debulker14amay be rotated concurrently with its retraction. As the debulker14ais retracted, the sharpenedproximal edge108 of theannular cutting member106 will sever a generally cylindrical bolus of tissue which surrounds the puncture tract, thereby accomplishing the desired enlargement of the initially formed penetration tract. The severed bolus of tissue will be drawn into, and captured within, the lumen (not shown) of thecounter-force member112 as the sharpenedproximal edge108 of theannular cutting member106 is retracted into contact with theannular cutting plate100.
• Thereafter, the counter-force member[0088]112 (having the severed bolus of tissue contained therewithin) and theretractable debulker14a, may be removed from the body along with thesubselective sheath12.
• 3. Sizing and Shaping of the Debulker to Optimize Flow Channel[0089]
• In ether[0090]debulking type system10,10athe particular geometry of thecutter member42 can assist in creation of the optimal passage, such as the enlarged bloodflow passageway EBP of the foregoing example. For example, theannular cutting member42 need not be of circular cross-sectional configuration as shown in FIG. 7a, but rather may be of oblong or oval configuration. Such oblong or oval shape of theannular cutting member42, when advanced through the puncture tract without rotation thereof, will form a channel of oval or oblong cross-sectional shape.
• Also, as shown on FIG. 4, the[0091]annular cuttiong member42 may be of tapered outer diameter, such that its distal cutting edge is of a first diameter d_xand its proximal end is of a second diameter d_y. Such tapering of theannular cutting member42 causes the tissue which is cut by thecutting edge46 to expand as thedebulker14 is advanced, thereby resulting in a more predictable diameter of the resultant channel.
• 4. Optional Energy-delivery Features which may be Incorporated into Any of these Tract-Enlarging Systems[0092]
• It will be appreciated that certain types of energy (e.g., laser, radio-frequency energy, electrical resistance heat, etc.) may be delivered to a tract-enlarging apparatus such as the[0093]debulker14,14aand/orcounter-traction member16,16a,16cto enhance the tract-enlarging efficiency of the system. Specific examples of systems which incorporate such energy emitting components are shown in FIGS. 10a-10f.
• FIGS. 10[0094]a-10cshow one energy-emitting debulking-type system which incorporates a bipolar, energy-emittingdebulker14′. FIGS. 10d-10fshow another energy-emitting, debulking-type system one electrode is located on an energy-emittingdebulker14′″ and another electrode is located on an energy-emittingcounter-traction member16″.
• With reference to the particular embodiment shown in FIGS. 10[0095]a-10c, the bipolar,radiofrequency debulker14′ comprises an elongatetubular member40′ having ahollow lumen44′ extending longitudinally therethrough. First and second energy-transmittingmembers204a,204bextend longitudinally through thetubular member44′, as shown in the cross sectional view of FIG. 10c. Adebulking electrode tip205 is mounted on the distal end of the tubular member.Such electrode tip205 incorporates a first radiofrequency-emittingelectrode206 and a second radiofrequency-emittingelectrode208, as shown in FIG. 10b. The firstenergy transmitting member204ais connected to thefirst electrode206 and the secondenergy transmitting member204bis connected to thesecond electrode208. Anannular insulator body210 is disposed between theelectrodes204a,204b. Abipolar radiofrequency generator200 is connected by way of awire202 to the first and secondenergy transmitting members204a,204bsuch that a circuit is completed between thegenerator200 and the respective first andsecond electrodes206,208. Thus, as the debulker is advanced in the distal direction through the interstitial passageway, the generator may be energized to cause radiofrequency current to pass between the annular distal surfaces of the first andsecond electrodes206,208, thereby effecting bipolar cutting or ablation of the tissue which surrounds the interstitial tract.
• In the alternative bipolar energy-emitting system shown in FIGS. 10[0096]d-10f, thefirst electrode206ais mounted on the distal end of thedebulker14″ and thesecond electrode208ais mounted on the proximal end of thecountertraction member16″, as shown. In this embodiment, the firstenergy transmitting member204aextends through thetubular member40″ of thedebulker14″ while the secondenergy transmitting member204bextends through theshaft60″ of thecountertraction member16″. Here again, the firstenergy transmitting member204ais connected to thefirst electrode206aof the secondenergy transmitting member204bis connected to thesecond electrode208a. In this manner when abipolar radiofrequency generator200 is connected to theenergy transmitting members204a,204b, a circuit is completed between the generator and the first andsecond electrodes206a,208asuch that radiofrequency current will pass between theelectrodes206a,206bin a manner which cuts or ablates the tissue which surrounds the interstitial tract.
• As those skilled in the art will appreciate, although bipolar embodiments are shown in FIGS. 10[0097]a-10f, similar monopolar embodiments may also be devised through the alternate use of a separate antenna or plate electrode wich attaches to the patients body to complete the circuit. Such monopolar embodiments may utilize only asingle electrode204 or206 to accomplish the desired cutting or ablation of tissue.
• In applications where radiofrequency energy is applied to the[0098]debulker14,14a, the radiofrequency energy may be applied continuously at 100 KHz-2 MHz, and preferably at about 500 KHx (i.e., 70 watts) until the cutting operation is complete. Alternatively, such radiofrequency energy may be delivered intermittently, in pulsed fashion, to avoid necrosis or damage to the adjacent tissue. Preferably, as illustrated graphically in FIGS. 14aand14b, when pulsed radiofrequency energy is used in lieu of continuous energy, the duty cycle of the pulsed energy will optomized to provide efficient tissue cutting while avoiding damage to surrounding tissue.
• FIGS. 10[0099]g-10ishow variants of a laser emitting debulker14b, wherein laser energy is used to cut or vaporize the tissue. The embodiment shown in FIGS. 10gand10g′ comprises an elongate flexible member having aguidewire lumen73 extending longitudinally therethrough, and a plurality of longitudinally extending, paralleloptical fiber bundles71 disposed in a generally circular array about the outer perimeter of the member, suchoptical fiber bundles71 terminating distally in lenses or otherlaser emitting surfaces77 such that a generally conical or annular pattern of laser light is projected from the distal end of the debulker14b.
• FIGS. 10[0100]_hand10h′ show an alternative laser emitting debulker14b′ wherein a central laser-transmittingoptical fiber bundle75 extends longitudnially through a portion of the debulker14b′ and terminates proximal to a generallyconical cavity76 formed in the distal end of the debulker14b′. Astationary prism77 having a plurality oflight guide grooves78 formed thereabout, is mounted on the distal end of thefiber bundle75 such that a generally conical pattern of laser light is projected from the prism, through theconical cavity76 and out of the distal end of the debulker14b′. An optional suction lumen79 may be provided in any of these laser embodiments, to enhance their efficiency (as described more fully herebelow) and/ or to aspirate away any residue or tissue particle which become severed during the procedure.
• FIGS. 10[0101]iand10i′ show another alternative laser emitting debulker14b″ wherein the central laser-transmittingoptical fiber bundle75′ is rotatable, terminates proximal to a generallyconical cavity76 formed in the distal end of the debulker14b′. Astationary prism77 having a singlelight guide groove78 formed thereon as shown, is mounted on the distal end of therotatable fiber bundle75′ such that as laser energuy is passed through theoptical fiber bundle75′ concurrently with its rotation, a generally conical pattern of laser light will be projected from the rotating prism mounted on the end of therotating fiber bundle75′, and such laser light pattern will be projected through theconical cavity76′ and out of the distal end of the debulker14b″.
• 4. Optional Application of Negative Pressure Through Debulker Lumen[0102]
• In either embodiment of the debulking-[0103]type system10,10a, negative pressure may be applied through the lumen of thedebulker14,14ato a) tension the tissue being cut so as to improve the cutting efficiency and/or predictability of the cut and/or b) draw the severed tissue into the lumen of thedebulker14,14aso as to capture and prevent escape of such severed tissue. Additionally, when suction or negative pressure is applied through the lumen of thedebulker14,14a, the operator may monitor the amount of negative pressure being generated as an indicator of whether the cuttingtip46,46ais presently in contact with tissue. In this manner, the operator may promptly discern when the cuttingtip46,46ahas passed fully through the desired tissue and into the opposite blood vessel or other cavernous space.
• [0104]5. Optional Apparatus for Enabling Operator to Determine When Debulking Operation is Complete
• In either debulking-[0105]type system10,10a, an optional sensor apparatus may be incorporated into thesystem10,10ato provide feedback or signal(s) to enable the operator to determine when the debulking operation is complete so that the advancement or retraction of thedebulker14,14amay be terminated at an appropriate time. As shown in FIG. 16, thesensor apparatus126 may comprise any suitable type of sensor which will indicate when thecutting edge46 of theannular cutting member42 is no longer in contact with tissue. Examples of the types ofsensor apparatus126 which may be used include sensors which measure impedance, temperature and/or electromagnetic resistance. Additionally, insystems10,10awhich utilize pulsed energy (FIG. 15) in combination with atemperature sensor126, the temperature sensed by thesensor126 may be used to manually or automatically (i.e., by a microprocessor or other controller) adjust the duty cycle of the pulsed energy to avoid exceeding a maximum desired temperature (e.g., the thermal necrosis temperature of the tissue—or some other temperature which has been identified as the maximum temperature to which the surrounding tissue may be heated).
• 6. Optional Apparatus for Controlling the Force Applied by the Debulker[0106]
• As shown in FIG. 16, either of the debulking-[0107]type systems10,10amay include aforce controlling apparatus128 for controlling the force applied by thedebulker14,14aupon the tissue being severed. In the particular embodiment shown thedebulker14 has a flexibletubular shaft40 formed of a proximal segment40aand adistal segment40b. Thedistal segment40bis slidably received within the lumen of the proximal segment40a, as shown. Theforce controlling apparatus128 comprises aspring130 which is attached to the proximal anddistal portions40a,40bof thetube40 such that, when the distal end of thedebulker14 is pressed against tissue, thespring130 will compress, thereby normalizing or regulating the force which is applied to the tissue. In embodiments where the debulker emits energy (e.g., radiofrequency energy, resistance heat) first and second energy-transmission contacts132,134 such that energy will be emited from the debulker only when thecontacts132,134 are in abuttment with each other. In this manner, such contact can be maintained only so long as thedebulker14 is engaging tissue, and when thedebulker14 emerges into the other vessel of open space, thespring130 will relax causingcontacts132,134 to separate and the flow of energy through thedebulker14 to cease.
• B. Dilation-type Systems[0108]
• FIGS.[0109]12-12cshow a dilation-typetract enlarging system10bof the present invention. This dilation-type system10bgenerally comprises a) atubular member120 having a distal tissue-abuttingrim122, and alumen124 extending longitudinally therethrough and b) ashaft126 having aballoon128 mounted thereon, aguidewire lumen130 extending longitudinally therethrough, and an inflation/deflation lumen132 extending from the proximal end thereof to the interior of the balloon. A guidewire which has previously been passed through the penetration tract which is to be enlarged, is inserted into the distal end of theguidewire lumen130. Thereafter, with theballoon128 in its deflated state (FIG. 12) and the balloon-bearing portion of theshaft126 positioned ahead of thetissue abutment rim122, thesystem10bis advanced over the guidewire GW until thetissue abutment rim122 abuts against or otherwise registers with tissue which surrounds or lies adjacent the proximal end of the penetration tract. Such abutment of therim122 against the tissue at the proximal end of the tract will deter further advancement of thesystem10b, and will signify to the operator that theballoon128 has become positioned within the penetration tract. Thereafter, inflation fluid is passed into theballoon128 through the inflation/deflation lumen132, causing theballoon128 to inflate. Such inflation of the balloon serves to dilate the tissue surrounding the penetration tract, thereby accomplishing the desired enlargement of the penetration tract. After the desired dilation of the penetration tract has been completed, the inflation fluid may be withdrawn from theballoon128 and thesystem10bis withdrawn from the body.
• C. Tissue-slicing Type Systems[0110]
• FIGS.[0111]17-18bshow tissue-cutting tract enlarging catheters10cof the present invention. These tissue cutting catheters10ccomprise a flexible catheter700 having a tissue cuttingdistal tip702aor702bmounted thereon.
• In the embodiment shown in FIG. 17, the tissue cutting[0112]distal tip702ais a generally cylindrical solid member which has a has a beveled leadingedge704 and aguidewire lumen706aextending longitudinally therethrough, as shown.
• In the embodiment shown in FIGS. 18[0113]a-18c, the tissue cuttingdistal tip702bhas two (2) taperedlateral surfaces709a,709bwhich converge to form adistal end710. Acentral guidewire lumen706bextends through thedistal end710, as shown.
• These tissue cutting catheters[0114]10cmay be advanced over a guidewire and through a small penetration tract, such that the beveleddistal edge704 orlateral surfaces706a&706bwill slice or slit the tissue without actually removing any tissue.
• D. Two Catheter Tract-Enlarging Systems[0115]
• FIG. 19 shows a two-catheter tract enlarging system[0116]10dwhich comprises comprises a) afirst catheter500 having a tract-enlarging apparatus (not shown) (e.g., a debulker, dialtor or tissue-slicing member of the above-described nature) advancable from an opening504 at or near the distal end of thefirst catheter500, and b) asecond catheter502 which has an anvil member506 (e.g., an abuttable surface or receiving cavity) which is sized and configured to correspond with the leading end of the tract-enlarging apparatus of the first catheter. Thefirst catheter500 is positioned in one of the anatomical conduits V, and the second catheter is positioned in the other anatomical conduit A, with itsanvil member506 located next to the penetration tract or passageway PT which is to be enlarged. Thereafter, the tract enlarging apparatus (not shown) is advanced through the tract or passageway PT until it registers with (e.g., abutts against or is received with) theanvil member506 of the second catheter. As the tract enlarging apparatus (not shown) is being advanced, theanvil member506 serves to provide counterforce against the tissue adjacent the initially formed tract or passageway PT so as to prevent unwanted protrusion or “tenting” of the tissue into the second anatomical conduit A, and to ensure efficient cutting of the tissue in cases where a debulking or tissue slicing type tract enlarging apparatus is used.
• Although exemplary embodiments of the present invention have been showr and described, it will be apparent to those having ordinary skill in the art that c number of changes, modifications, or alterations to the invention as describer herein may be made, none of which depart from the spirit of the present invention All such changes, modifications and alterations should therefore be seen as withir the scope of the present invention as described herein and recited in the following claims.[0117]

Claims (39)

What is claimed is:

1. An advanceable debulking system for enlarging an interstitial tract which extends outwardly from the lumen of an anatomical conduit, said system comprising:

a counter-traction member which is advanceable, in a first direction, at least partially through the interstitial tract, said counter-traction member having at least one tissue engagement surface formed thereon to engage tissue which is adjacent the interstitial tract, said counter-traction member being useable to apply a force which is directed in a second direction substantially opposite said first direction, upon the tissue which has been engaged by said tissue-engagement member; and,

a debulker which is advanceable out of the lumen of the sheath, in the first direction, to remove tissue which lies adjacent the interstitial tract, thereby enlarging the interstitial tract.

2. The system ofclaim 1 wherein the debulker is an elongate member having a lumen which extends longitudinally therethrough, and wherein said counter-traction member extends coaxially through the lumen of the debulker.

3. The system ofclaim 1 wherein the debulker has a distal end, and wherein a tissue-receiving chamber is formed in the distal end of the debulker such that tissue which has been removed by the debulker will enter said tissue-receiving chamber.

4. The system ofclaim 1 wherein a guidewire lumen extends through said counter-traction member such that said counter-traction member may be advanced over a guidewire which extends through the interstitial tract.

5. The system ofclaim 1 further comprising a sheath having a lumen extending longitudinally therethrough, the lumen of said sheath being sized to permit said debulker and said countertraction member to pass therethrough.

6. The system ofclaim 5 wherein said sheath has a distal end opening out of which said debulker and said countertraction member are passable.

7. The system ofclaim 6 wherein said sheath has a side opening out of which said debulker and said countertraction member are passable.

8. The system ofclaim 7 wherein the lumen of the sheath further comprises a deflector surface which is configured and located to deflect said debulker out of said side opening as said debulker is advanced in the distal direction therethrough.

9. The system ofclaim 1 wherein said debulker comprises an elongate member having a distal end whereupon an annular cutter is mounted, said annular cutter having a sharpened leading edge so as to sever tissue as it is advanced in the first direction.

10. The system ofclaim 9 wherein at least the annular cutter of said debulker is rotatable.

11. The system ofclaim 9 further comprising a motor for rotatably driving at least the annular cutter of said debulker.

12. The system ofclaim 1 wherein said countertraction member comprises an elongate shaft having a radially expandable tissue-engaging apparatus formed thereon, said radially expandable tissue-engaging apparatus having:

a) a radially collapsed configuration which is sufficiently small in diameter to pass at least partially through the interstitial tract; and,

b) a radially expanded configuration which is sufficiently large in diameter to engage tissue which surrounds the interstitial tract.

12. The system ofclaim 11 wherein said radially expandable apparatus is selected from the group of radially expandable apparatus consisting of:

i.) a balloon;

ii.) at least one barb;

iii.) at least one hook;

iv.) a plurality of outwardly curving tissue engagement members, each of said having proximal and distal ends which are attached to the shaft and outwardly curving mid-sections, the mid sections of said tissue engagement members being curved outwardly from said shaft when said

v.) a plurality of splayable tissue engagement members having distal ends which are unattached to the shaft of the counter-traction member and positioned at spaced apart locations thereabout, the distal ends of said tissue engagement members being splayable outwardly from the shaft when in their radially expanded configuration;

and,

vi.) a resilient tubular member which has a radially flared distal end, the flared distal end of said resilient tubular member being advanceable, in the first direction, from the distal end of the shaft of said counter-traction member.

13. The system ofclaim 1 wherein the debulker further comprises: at least one energy-transmitting member which may be connected to an energy source, said energy transmitting member being operative to transmit energy from an energy source connected thereto, to a location on the debulker at which said energy will enhance the ability of the debulker to remove tissue.

14. The system ofclaim 13 wherein the energy-transmitting member is a member which transmits radio-frequency energy.

15. The system ofclaim 14 further comprising: a radio-frequency generator attached to said energy-transmitting member.

16. The system ofclaim 14 wherein said debulker is an elongate member which has a tissue-severing surface formed on the distal end thereof, and wherein the energy-transmitting member is positioned and constructed to transmit radiofrequency energy to the tissue-severing surface of the debulker.

17. The system ofclaim 16 wherein the tissue-severing surface comprises a leading edge formed on an annular cutting member.

18. The system ofclaim 1 further comprising: A dilator formed on the distal end of said counter-traction member to dilate the interstitial tract as the counter-traction member is advanced therethrough.

19. The system ofclaim 18 wherein the dilator is a frusto-conical dilator member having a distal end of a first diameter and a proximal end of a second diameter larger than said first diameter.

20. The system ofclaim 18 wherein: the counter-traction member has a longitudinal axis; and, an annular tissue-abutment surface is formed on the proximal end of the frus which is generally perpendicular to the longitudinal axis of the counter-traction member.

21. The system ofclaim 20 wherein: an annular cutting member is formed on the distal end of the debulker; and, the annular tissue abutment surface comprises a cutting plate which is sized, configured and positioned such that when the debulker is advanced in the first direction, the annular cutting member will register with the cutting plate.

22. A retractable debulking system for enlarging an interstitial tract which extends outwardly from the lumen of an anatomical conduit, said system comprising:

a tubular, proximal counter-force member which has at least one tissueengaging surface formed on the distal end thereof, said proximal counter-force member being advanceable into the lumen of the anatomical conduit from which said interstitial tract extends such that its tissue-engaging surface engages tissue adjacent the interstitial tract; and, a retractable debulker which is advanceable out of the distale end of the proximal counter-force member and through the interstitial tract in a first direction, said debulker being subsequently retractable in a second direction opposite said first direction, said debulker having a at least one tissue removing surface formed on the proximal end thereof to remove tissue located adjacent the interstitial tract as the debulker is retracted in the second direction through the interstitial tract; said proximal counter-traction member being operative to apply a counterforce in the first direction against the tissue adjacent the interstitial tract, as the debulker is being retracted in the second direction to remove said tissue.

23. The system ofclaim 22 wherein the retractable debulker has aproximal tissue cutting surface, and wherein a tissue-receiving chamber is formed with the debulker adjacent to said tissue cutting surface, such that tissue which has been removed by the debulker will enter said tissue-receiving chamber.

24. The system ofclaim 22 wherein a guidewire lumen extends through said retractable debulker such that said retractable debulker may be advanced over a guidewire which extends through the interstitial tract.

25. The system ofclaim 22 further comprising a sheath having a lumen extending longitudinally therethrough, the lumen of said sheath being sized to permit said debulker and said countertraction member to pass therethrough.

26. The system ofclaim 25 wherein said sheath has a distal end opening out of which said debulker and said countertraction member are passable.

27. The system ofclaim 25 wherein said sheath has a side opening out of which said debulker and said countertraction member are passable.

28. The system ofclaim 27 wherein the lumen of the sheath further comprises a deflector surface which is configured and located to deflect said debulker out of said side opening as said debulker is advanced in the distal direction therethrough.

29. The system ofclaim 22 wherein said retractable debulker comprises an elongate member having a proximal end whereupon an annular cutter is mounted, said annular cutter having a sharpened leading edge so as to sever tissue as it is retracted the proximal direction throught he penetration tract.

30. The system ofclaim 29 wherein at least the annular cutter of said retractable debulker is rotatable.

31. The system ofclaim 9 further comprising a motor for rotatably driving at least the annular cutter of said debulker.

32. A laser debulking apparatus, useable for enlarging an interstitial penetration tract, said apparatus comprising:

an elongate flexible member having a guidewire lumen extending longitudinally therethorugh;

a plurality of laser transmitting members extending longitudinally through said flexible member, said laser transmitting members being disposed in a generally annular array,

each of said laser transmitting members having a distal end associated with a laser light transmitting surface whereby laser light from that laser transmitting member will be projected from said flexible member, such that when laser energy is concurrently passed through all of said laser transmitting members, a generally annular patern of laser light will be projected from said apparatus.

33. The apparatus ofclaim 32 further comprising a suction lumen extending through said flexible member to apply suction to the area into which said pattern of laser light is projected.

34. A laser debulking apparatus, useable for enlarging an interstitial penetration tract, said apparatus comprising:

an elongate flexible member having a guidewire lumen extending longitudinally therethorugh;

a laser transmitting member extending longitudinally through said flexible member;

a prism having at least one light guide groove formed therein, said prism being rotatably positioned on the end of said laser transmitting member such that laser energy which passes through said laser transmitting member will pass into said prism and will be caused by said at least one light guide groove and the concurrent rotation of said prism, to be projected in a generally conical pattern from said apparatus.

35. The apparatus ofclaim 34 further comprising a suction lumen extending through said flexible member to apply suction to the area into which said pattern of laser light is projected.

36. The apparatus ofclaim 34 wherein said laser transmitting member is rotatable, and wherein said prism is mounted on the distal end of said laser transmitting member so as to rotate concurrently with said laser transmitting member.

37. A laser debulking apparatus, useable for enlarging an interstitial penetration tract, said apparatus comprising:

an elongate flexible member having a guidewire lumen extending longitudinally therethorugh;

a laser transmitting member extending longitudinally through said flexible member;

a prism having a plurality of light guide grooves formed therein, said light guide grooves being disposed in a generally annular array, said prism being positioned on the end of said laser transmitting member such that laser energy which passes through said laser transmitting member will pass into said prism and will be caused by said plurality light guide grooves to be projected in a generally conical pattern, from said apparatus.

38. The apparatus ofclaim 37 further comprising a suction lumen extending through said flexible member to apply suction to the area into which said pattern of laser light is projected.

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