INTRAVASCULAR CATHETER WITH INFUSION ARRAY

Abstract: An intravascular catheter provides means for infusing an agent into a treatment site in a body lumen and means for deploying the infusing means adjacent the treatment site which operate independently of one another. In a preferred embodiment a flexible catheter body (20) has an expansion member (28) attached to its distal end in communication with an inflation passage (54), and an infusion array (30) disposed about the expansion member in communication with one or more delivery passages (36). The infusion array includes a plurality of delivery conduits (32) having laterally oriented orifices (34). The delivery conduits (32) may be extended radially from the catheter body (20) to contact a treatment site by expanding the expansion member (28) with an inflation fluid. An agent may be introduced into the delivery passages (36) and infused into the treatement site through orifices (34) in the delivery conduits (32). The expansion member (28) may be expanded for dilation of the lumen before, during, or after infusion.

Description: INTRAVASCTJLAR CATHETER WITH INFUSION ARRAY CROSS-REEERENCE TO RELATED APPLICATIONS This is a conώiuation-in-part of application Serial No. 07/969,595, filed November 2, 1992, the complete disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION This invention relates generally to drug-delivery devices, and more specifically to intravascular catheters for delivery of therapeutic agents from within a lumen of a blood vessel or other body organ. In percutaneous transluminal angioplasty procedures, a catheter having an expandable distal end, usually in the form of a balloon, is positioned in a lumen of a blood vessel with the distal end disposed within a stenotic atherosclerotic region of the vessel. The expandable end is then expanded to dilatate the vessel and restore adequate blood flow through the region of stenosis. Whereas angioplasty has gained wide acceptance, it continues to be plagued by two major problems, abrupt closure and restenosis. Abrupt closure refers to the acute occlusion of a vessel immediately after or within the initial hours following the dilatation procedure. This type of complication, occurring in approximately one in twenty cases, frequently results in myocardial infarction and death if blood flow is not quickly restored. The primary mechanisms of abrupt closures are arterial dissection and/or thrombosis. It is postulated that the ability to deliver agent (e.g. an Cantithrombotic drug) directly into the arterial wall at the time of angioplasty would reduce the incidence of thrombotic acute closure. Restenosis refers to the re-narrowing of an artery after an initially successful angioplasty. Restenosis usually occurs within the initial six months after angioplasty. It is postulated that the delivery of certain agents direcdy into the arterial wall would interrupt the cellular events leading to restenosis. The potential utility of local intramural drug delivery is not limited to atherosclerotic coronary artery disease. Other sites of atherosclerosis (e.g. renal, iliac, femoral, distal leg and carotid arteries as well as saphenous vein grafts, synthetic grafts and arteriovenous shunts used for hemodialysis) would also be appropriate for local intramural drug delivery. Local intramural therapy may also prove efficacious in non- arterial structures, including the prostate via the prostatic urethra (benign prostatic hypertrophy, prostatitis and adenocarcinoma), fallopian tubes via its lumen (strictures), and brain parenchyma (Parkinson's Disease). At present, intravenous medications are delivered systemically by vein or regionally (e.g. intracoronary infusion). Systemic delivery is generally not well suited to the treatment of disease entities with a single site or several discrete sites of interest (e.g., coronary artery disease) in that it necessitates: (1) exposing sites other than the site of interest to medication where it may have an adverse effect; (2) infusing sufficient quantities of agent to achieve the concentration throughout the entire volume of distribution; and (3) exposing the agent to degradation and elimination by one or more organ systems remote from the site of interest. Furthermore, the tissue concentration that can be achieved at the site of interest is often limited by the effects of the agent at distant sites. Local intramural delivery obviates these problems. Therefore, it is of particular importance to deliver the therapeutic agent directly to the treatment site by contact with or penetration into the tissue, rather than simply releasing the agent into the blood stream in the vicinity of the treatment site. While various catheters have been developed for delivery of agents to a treatment site within a vessel or organ lumen, such devices have suffered from certain drawbacks. In particular, known agent delivery catheters generally do not permit delivery of an agent directly to a treatment site independently of the deployment of the delivery mechanism adjacent the lumen wall. For example, known agent delivery catheters frequently employ an expandable member such as a balloon which is expanded near the treatment site and brought into contact with the lumen wall. A therapeutic agent is usually delivered through pores on the surface of the balloon. In such devices, the pressurized fluid which expands the balloon is also the vehicle for the agent. Therefore, the balloon cannot be expanded without expelling the drug/vehicle mixture. This scheme is inefficient, in that agent is expelled before the periphery of the balloon is adjacent to the lumen wall. This scheme also prevents delivery of agent without at least partly expanding the balloon. The deployment mechanism (i.e. balloon expansion) and the drug delivery mechanism are inextricably linked. Thus, where it would be desirable to dilatate a region of stenosis in an artery without simultaneously infusing an agent, known drug delivery catheters are of little use. Moreover, where it would be desirable to infuse an agent within a body lumen without deploying the balloon, known drug delivery catheters are similarly ineffective. Furthermore, in devices which employ the agent/vehicle mixture to pressurize and expand the balloon, the reversal of fluid flow required to retract the balloon tends to draw blood into the device, preventing further use of the device until the blood has been expelled. Typically, this prevents multiple treatments without withdrawing the catheter for purging or replacement. A further drawback of known drug delivery devices stems from their incapacity for selective delivery of agent to various sectors of an organ lumen. Such directional treatment may be advantageous, where, for example, only a particular portion of a vessel wall is diseased and infusion to non-diseased regions is undesirable. Further, in certain procedures, the ability to selectively infuse different agents in different areas of the lumen may be advantageous. In known devices, it is not possible to deliver agent selectively into a particular sector of the artery, or to deliver two or more different agents into different sectors simultaneously. Moreover, known drug delivery catheters which infuse an agent through a porous balloon generally release the agent at relatively low pressures so as to merely bathe or coat the vessel wall where it is contacted by the infusion member. With such devices, the agent will generally not penetrate the lumen wall and may not provide effective therapy. Treatment would be more effective if the therapeutic agent were delivered at pressures sufficient to achieve penetration to the adventitial layer of the organ wall. A drug delivery catheter is therefore desired which can be used to administer therapeutic agents to a treatment site within a lumen of a body organ by direct contact with the lumen wall tissue. Most desirably, the drug delivery catheter will be deployable against the treatment site independendy of the delivery of the agent to the site. The catheter should also allow dilatation of a vessel with or without delivery of a drug or other therapeutic agent. Preferably, the catheter should be capable of injecting an agent at pressures sufficient to penetrate the adventitial layer of an artery. In addition, the catheter should allow selective infusion of an agent in various radial directions, and simultaneous infusion of two or more different agents in different radial directions. The catheter should further be useful for treatment of blood vessels as well as a variety of other body organs. Description of the Background Art Balloon-tipped catheters appropriate for angioplasty treatment procedures are described in, for example, U.S. Patent No. 5,041 ,089, U.S. Patent No. 4,323,071 , U.S. Patent No. 4,292,974, U.S. Patent No. 4,762,129, and U.S. Patent No. 4,775,371. A catheter for locally applying medication to the wall of a blood vessel or other lumen is described in U.S. Patent No. 5,087,244, the catheter having a balloon near its distal end which is expanded with a medication, which then flows through minute holes in the balloon surface at a low flow rate. U.S. Patent No. 4,994,033 describes an intravascular drug delivery catheter having a pair of expansion members concentrically arranged near its distal end wherein an agent is delivered to the outer expansion member, after which the inner expansion member is expanded, thereby expanding the outer member against the vessel wall and forcing the agent through minute holes in the outer member to bathe the vessel wall. U.S. Patent No. 5,021,044 describes an intravascular drug delivery catheter having a plurality of holes on the outer surface of the catheter body through which an agent may be delivered to a site within a vessel. U.S. Patent No. 5,112,305 describes a catheter for delivery of therapeutic agents to an interior wall of a vessel, the catheter having a balloon near its distal end with tubular extensions capable of projecting from its outer surface. An agent is delivered to the balloon which both expands the balloon and flows through the tubular extensions into the vessel wall. Other drug delivery devices are described in U.S. Patent No. 4,693,243, U.S. Patent No. 4,406,656, U.S. Patent No. 5,015,232, U.S. Patent No. 5,087,247, and U.S. Patent No. 4,850,969. SUMMARY OF THE INVENTION The present invention provides an intravascular catheter for administering a therapeutic agent to a treatment site in the wall of a vessel. The catheter will have particular usefulness in treating arterial stenoses in conjunction with angioplasty, but will have further application in treating diseases affecting other body organs, such as the prostate, biliary ducts and genital-uretal system. The catheter of the present invention is particularly advantageous over known devices because it permits deployment of the delivery mechanism adjacent to the treatment site independently of the delivery of the agent to the treatment site. The invention thereby facilitates dilatation to be performed with or without infusion of an agent, as well as infusion of an agent before, during, after, or without dilatation. The catheter of the present invention further permits directional infusion of one or more agents within a body lumen. Moreover, the catheter improves the effectiveness of drug treatment by infusing the agent at pressures sufficient to achieve penetration into the adventitial layer of the organ. In a specific embodiment, an apparatus for infusing an agent to a treatment site in a body lumen comprises a catheter body having a distal end, a proximal end and first and second passages therebetween; a guidewire extending from the distal end of the catheter body; an expansion member attached to the catheter body near the distal end, the interior of the expansion member being in fluid communication with the first passage; and an infusion array in communication with the second passage and disposed adjacent a lateral surface of the expansion member so as to be deployable adjacent to the treatment site by deployment of the expansion member, wherein the infusion array is operable for infusing an agent to the treatment site independently of deployment of the expansion member. In a preferred embodiment, the infusion array comprises at least a first tubular delivery conduit having a plurality of orifices on a surface thereof and an axial passage which is in communication with the second passage in the catheter body. Usually, the infusion array will include a plurality of tubular delivery conduits disposed at various positions about the periphery of the balloon. The orifices in the delivery conduits will typically be radially-oriented so as to open directly onto the treatment site when the conduits are positioned adjacent to the vessel wall. The delivery conduits may be connected to a single delivery passage in the catheter, but in a preferred embodiment, the catheter body will include a plurality of delivery passages, each passage being in communication with one delivery conduit. An agent may be infused through selected delivery conduits by delivering the agent through the corresponding delivery passage or passages. In this way, infusion may be performed at selected directions, and two or more agents may be infused through selected delivery conduits simultaneously. The expansion member may comprise a balloon similar to those of conventional balloon dilatation catheters. In a preferred embodiment, the expansion member and delivery conduits will be integrated into a single, monolithic extrusion, the conduits comprising passages in or along the wall of the expansion member. Alternatively, the delivery conduits may be structurally separate from the balloon and disposed on its exterior surface. The expansion member may alternatively comprise a balloon fixed to an entirely separate dilatation catheter removably disposed in an axial passage through the catheter body. In this embodiment, the delivery conduits will usually be mounted to an expandable support member disposed about an opening in the catheter body in which the balloon of the removable dilatation catheter resides. The expansion member will be expanded using an expansion fluid supphed through the first passage in the catheter body. Because the expansion member is fluidly isolated from the delivery conduits, the expansion fluid will not include the infusion agent, which is infused separately via the device. Deployment of the expansion member brings its lateral wall along with the delivery conduits of the infusion array adjacent to the treatment site. The expansion member is used only for deploying the infusion array adjacent the vessel wall and/or dilatating the vessel, and plays no part in infusing an agent through the infusion array. The infusion conduits retain their fluid-conducting capacity whether positioned against the treatment site or retracted toward the center catheter body. Thus, an agent may be infused through the infusion array irrespective of whether the expansion member is expanded or retracted. The infusion array will be configured to infuse an agent at sufficient pressure to penetrate to a depth of at least the media, and preferably into the adventitia of the arterial wall. In a preferred embodiment, the delivery conduits of the infusion array will be composed of polyester, with an inner diameter on the order of 0.1- 0.2mm, a wall thickness on the order of 0.05-0. lmm, and orifices of 10-50 μm in diameter. The use of a plurality of delivery conduits of relatively high stiffness and small cross-section, each supplied through independent delivery passages from the proximal end of the device, rather than a single delivery passage with a manifold at the distal end, provides a stiffer hydraulic system. This allows for the infusion of more precisely-metered doses than is possible in known devices and results in a substantially more efficient method of agent delivery. In a preferred aspect of the method of die present invention, an agent delivery catheter is positioned in a blood vessel with an infusion array at the distal end of the catheter near the treatment site. An expansion member at the distal end of die catheter, which is fluidly isolated from die infusion array, is deployed so as to position the infusion array adjacent a treatment site in the vessel lumen. Thereafter, an agent is delivered to the infusion array through at least one delivery passage in the catheter. The agent is then infused into the treatment site through a plurality of orifices in the infusion array. In a particular embodiment, the agent is delivered from the proximal end of d e catheter through a plurality of separate delivery passages to a plurality of delivery conduits at the distal end of d e device, d e orifices of the infusion array being arranged on die outermost surfaces of the delivery conduits. In this way, delivery of die agent to each delivery conduit may be controlled independendy. Thus, an agent may be infused through a first delivery conduit without infusing the agent through a second delivery conduit, or a first agent may be infused through a first delivery conduit while a second agent is infused through a second delivery conduit. In a specific embodiment, d e method will be used for treatment of coronary artery disease, wherein the cadieter is positioned widi the infusion array near a stenotic or otherwise diseased site in an artery. Usually, a fixed guidewire mounted at me distal end of die catheter, or a movable guidewire extending through a guidewire passage in the catheter, will be used to guide die cadieter into the vessel. The expansion member may be deployed to dilatate the artery for restoration of adequate blood flow, wid or without infusion of an agent tiirough the infusion array. Before, δ during, after, or without dilatation, one or more agents may be infused dirough the infusion array into the treatment site. In alternative embodiments, me meti od of the invention may be used for treatment of various other body organs, including die bihary ducts, or the genital-uretal organs. A further understanding of d e nature and advantages of die invention may be realized by reference to d e remaining portions of d e specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an agent delivery cadieter constructed in accordance widi the principles of the present invention. Fig. 1A is a transverse cross-section of a distal portion of d e catheter of Fig. 1. Fig. IB is a transverse cross-section of d e catheter shaft of the catheter of Fig. 1. Fig. IC is a side cross-section of d e proximal end of d e catheter of Fig. 1. Fig. ID is a transverse cross-section dirough the proximal end of die catheter of Fig. IC. Fig. IE is a longitudinal cross-section of d e distal end of die cadieter of Fig. 1 cutting through two drug delivery conduits. Figs. 2A-2C are transverse cross-sections of a portion of d e expansion member and delivery conduits of die cadieter of Fig. 1., showing various alternative embodiments tiiereof. Fig. 3A is a perspective view of a further embodiment of an agent delivery catheter constructed in accordance widi die principles of the present invention. Fig. 3B is a transverse cross-section of a proximal end of me catheter of Fig. 3 A. Fig. 3C is a transverse cross-section of d e cadieter shaft of the catheter of Fig. 3A. Figs. 4 A and 4B are perspective views of a further embodiment of an agent dehvery catheter constructed in accordance widi the principles of the present invention, showing the expansion member in d e unexpanded and expanded configurations, respectively. Fig. 4C is a transverse cross-section of a distal portion of d e catheter of Fig. 4B. Fig. 4D is a transverse cross-section of die catheter shaft of the catheter of Fig. 4B. Fig. 4E is a longitudinal cross-section of the distal end of die cadieter of Fig. 4B. Fig. 5 is a perspective view of a further embodiment of an agent dehvery cadieter constructed in accordance with die principles of the present invention. Fig. 6 is a perspective view of still another embodiment of a drug dehvery catheter constructed in accordance widi d e principles of die present invention. Fig. 7 is a side view of a distal end of a further embodiment of a catheter constructed in accordance wid die principles of the present invention. Figs. 7A-7B are transverse cross-sections of die catheter of Fig. 7 through the cadieter shaft and dirough die expansion member, respectively. Fig. 8 A and 8B are side views of die cadieter of Fig. 1 positioned widiin a body lumen according to the principles of die method of d e present invention. Fig. 9 is a perspective view of a further embodiment of an agent dehvery cadieter constructed in accordance widi die principles of the invention. Figs. 10A and 10B are side elevational views of a distal portion of die catheter of Fig. 9 in undeployed and deployed configurations, respectively. Fig. 11 is a transverse cross-section dirough line 11-11 in a proximal portion of die shaft of d e cadieter of Fig. 9. Figs. 12A-12E are transverse cross-sections through line 12-12 at the distal end of die shaft in the catheter of Fig. 9 illustrating various embodiments of me stiffening elements in the infusion array. Fig. 12F is a top elevational view of a further embodiment of die stiffening element in the cadieter of Fig. 9. Fig. 13 is a side cross-section of a further embodiment of d e infusion array of the catheter of Fig. 9 wherein the dehvery conduits are secured to d e periphery of an elastomeric sleeve. Fig. 14A is a transverse cross-section of die infusion array of Fig. 13. Fig. 14B is a transverse cross-section dirough d e infusion array wherein the elastomeric sleeve is disposed external to the dehvery conduits. Figs. 15A-15B are a side cross-section and a perspective view, respectively, of d e distal tip of d e catheter of Fig. 9. Fig. 15C is a side cross-sectional view of a further embodiment of a distal tip constructed in accordance wid die principles of die invention. Fig. 16 is a side cross-section of die manifold assembly at d e proximal end of d e catheter of Fig. 9. Figs. 17A-17D are side views illustrating the catheter of Fig. 9 positioned in a body lumen according to d e metiiod of die invention. Figs. 18A-18C are side cross-sectional views of a distal portion of the infusion cadieter of Fig. 9 illustrating d e radiopaque markers on e stiffening elements. DESCRIPTION OF SPECIFIC EMBODIMENTS Referring to Fig. 1, the intravascular drug dehvery cadieter of die present invention includes an elongate flexible shaft 20 having a distal end 22 and a proximal end 24. A movable guide wire 26 extends dirough d e cadieter and beyond its distal end 22. An expansion member 28 is attached to d e cadieter shaft 20 near distal end 22. An infusion array 30 comprising dehvery conduits 32 and orifices 34 is disposed about die exterior surface of expansion member 28. Conduits 32 are in communication wi dehvery passages 36 in catheter shaft 20. A housing 38 is mounted to proximal end 24 of cadieter shaft 20. Housing 38 includes an agent introduction port 40 and an inflation fluid introduction port 42. A distal portion of die catheter will now be described widi reference to Figs. 1A and IE. A guidewire passage 44 is disposed centrally in shaft core 46, through which guidewire 26 is slidably disposed. Expansion member 28 surrounds shaft core 46, with dehvery conduits 32 disposed about its periphery. Dehvery conduits 32 include an axial passage 50 in communication widi orifices 34. Distal ends 33 of dehvery conduits 32 are sealed. In a preferred embodiment, dehvery conduits 32 and expansion member 28 comprise a single integrated, monohd ic extrusion, widi the dehvery conduits forming longitudinal passages in die wall of the expansion member. It will be understood tiiat the cadieter of d e present invention may have any of a variety of guidewire configurations. For example, as shown in Figs. 7, 7A and 7B, rather than being disposed centrally in the shaft core, guidewire passage 244 may be offset from the center axis independent of and parallel to inflation lumen 54. Moreover, such a guidewire passage need not extend dirough d e entire lengtii of shaft 20, but may instead have a lateral opening 245 at a point along shaft 20 through which guidewire 26 exits the offset guidewire passage 244 and shaft 20, such tiiat guidewire 26 and shaft 20 are independent of each otiier at the proximal end of d e device. Such an offset guidewire is described in U.S. Patent No. 4,748,982, die complete disclosure of which is incorporated herein by reference. Furthermore, a fixed guidewire (not shown) extending from distal end 22 may be used in lieu of movable guidewire 26. As illustrated in Figs. 2A-2C, dehvery conduits 32 may be integrated with expansion member 28 at various positions relative to exterior surface 48. In the embodiment of Fig. 2A, dehvery conduits 32 are disposed exterior to surface 48 so as to protrude d erefrom. In the embodiment of Fig. 2B, dehvery conduits 32 are disposed primarily in the interior of expansion member 28 widi orifices 34 extending dirough die d ickness of the expansion member, such that surface 48 has a substantially smootii contour about the periphery of die expansion member. Fig. 2C shows another embodiment wherein dehvery conduits 32 are disposed centrally in the wall of expansion member 28, producing only a slight protuberance on surface 48. The number of dehvery conduits 32 may vary from one to eight or more, O but in a preferred embodiment, mere will be four dehvery conduits spaced at approximately 90 degrees about d e circumference of expansion member 28. Dehvery conduits 32 may be disposed in various arrangements about the periphery of expansion member 28, both symmetrically and asymmetrically. For example, the dehvery conduits may be arranged such tiiat a majority or all of the conduits are on one side of die expansion member. Or, the dehvery conduits may be arranged widi two pairs of closely-spaced conduits on opposing sides of expansion member 28. Moreover, the dehvery conduits may be of different diameters, and may have varying sizes, shapes and arrangements of orifices 34. Orifices 34 may be in a single row, but may also be in a non-linear arrangement, or in multiple rows or groups on each dehvery conduit. Dehvery conduits 32 will preferably have sufficient rigidity in the transverse direction so as to remain uncollapsed when positioned by expansion member 28 against a wall of artery. Dehvery conduits 32 and orifices 34 will preferably be configured to infuse an agent at sufficient pressure to penetrate into die adventitial layer of the organ wall. Usually, the device will achieve penetration to at least die media. Pressures of at least 4 atmospheres are generally necessary to achieve such penetration. The present invention, in an exemplary embodiment, will infuse d e agent at a pressure of up to 10 atmospheres or more. This will be accomphshed by delivering the agent under pressure from the proximal end of me catheter through dehvery passages 36. In addition, d e geometry and material of the dehvery conduits 32 will be selected to facihtate penetrative infusion. In a preferred embodiment, die dehvery conduits 32 will be composed of polyester, with an interior diameter of about 0.1-0.2 mm, and a wall thickness of about 0.05-0.10 mm. Orifices 34 will have a diameter in the range of 10 to 50 μm. Referring now to Fig. IB, cadieter shaft 20 proximal to expansion member 28 includes shaft core 46 widi guidewire 26 extending dirough guidewire passage 44. An outer body 52 of the catheter shaft surrounds an inflation passage 54. Dehvery passages 36 and outer body 52, in a preferred embodiment, comprise a monohthic extrusion, widi a variety of possible configurations. In die embodiment of Fig. IB, the dehvery conduits 36 are disposed on d e exterior surface 56 of outer body 52. Other possible configurations will be similar to those illustrated in Figs. 2B and 2C and described above in connection widi dehvery conduits 32. Further embodiments are shown in Figs. 4A-4E and Fig. 5, described more fully below. Expansion member 28 may be adhesively attached to cadieter shaft 20, but will preferably be formed as a single extrusion, along with dehvery passages 36 and dehvery conduits 32, forming a continuous, monohdiic structure from proximal end 24 to distal end 22. While known cadieter fabrication techniques have been used to form a balloon at the distal end of a tubular shaft, it is heretofore unknown to form a balloon at the distal end of a monohdiic extruded structure with dehvery conduits witiiin the wall of the balloon and dehvery passages within the wall of the shaft in communication widi die dehvery conduits. Referring now to Figs. IC and ID, housing 38 includes an annular manifold 58 in communication widi a passage 60 dirough agent introduction port 40. Distribution passages 62 extend distally from manifold 58 to cadieter body 20, where tiiey connect to dehvery passages 36. Inflation passage 54 extends dirough housing 38 and connects to passage 64 in inflation port 42. Shaft core 46 is disposed witiiin inflation passage 54, wid guidewire 26 extending dirough guidewire passage 44. A further embodiment of die catheter of d e present invention is illustrated in Figs. 3A-3C. In this embodiment, housing 38 at the proximal end of die device has a plurality of agent introduction ports 140, each introduction port being in communication widi one of dehvery passages 36 in catheter shaft 20 via connection passages 162. In other respects, the catheter is much like that described above in connection with Figs. 1A-1E, except that dehvery passages 36 and dehvery conduits 32 (not visible) have die configuration illustrated in Figs. 2B and 3C, respectively. By providing separate introduction ports 140 for each dehvery passage 36 and dehvery conduit 32, the invention as embodied in Figs. 3A-3C permits directional infusion of one or more agents through orifices 34 in different dehvery conduits 32 of infusion array 30. This may be advantageous where only a particular portion of a vessel is to be treated, and infusion to other portions is undesirable. Directional infusion may further be useful to infuse a first agent through one or more dehvery conduits 32 at selected directions, while simultaneously infusing one or more other therapeutic agents through other dehvery conduits. In tiiis way, for example, a growth- inhibiting agent may be dehvered to a stenotic region of d e vessel through the dehvery conduits on one side of d e cadieter, while an anti-coagulant is dehvered through the dehvery conduits on another side of die catheter. A further embodiment of me cadieter of die present invention, illustrated in Figs. 4A-4E, comprises a separate dilatation cadieter 70 of conventional construction removably disposed in an axial passage 72 in catheter body 20. An expandable support member 74 is attached to die distal end of cadieter body 20, more clearly illustrated in Figs. 4C and 4E. Support member 74 comprises a tubular structure having a plurality of separate support sections 75. Dehvery conduits 32 are disposed on a lateral surface of support sections 75, and are in communication with dehvery passages 36 in cadieter body 20. Orifices 34 are disposed on a lateral surface of dehvery conduits 32, widi distal ends 33 of dehvery conduits 32 sealed. While support member 74 and dehvery conduits 32 are shown as separate structures mounted to cadieter body 20, it will be understood tiiat catheter body 20, support member 74 and dehvery conduits 32 may comprise a single (monohdiic) extrusion, as described above in connection widi Figs. 1A-1E. Removable dilatation catheter 70 is shdably disposed in axial passage 72 in catheter body 20. The dilatation cadieter 70 will be of conventional construction, and includes a guidewire passage 76 in a core 80 as shown in Fig. 4D, dirough which guidewire 26 is shdably inserted. An outer casing 82 surrounds core 80, defining an inflation passage 78. An expansion member 84 is formed from, or adhesively mounted to d e distal end of casing 82, and is sealed at distal end 22 about core 80. When dilatation catheter 70 is positioned in catheter body 20, expansion member 84 resides witiiin interior lumen 86 of support member 74. Guidewire 26 and/or core member 80 extend distally through a distal opening 88 in support member 74. Support member 74 will be constructed of a material similar to that of expansion member 84 so as to expand tiierewitii. When expansion member 84 is inflated, as shown in Figs. 4B and 4C, support sections 75 are distended and separated as they expand outward wid die expansion member. A further alternative embodiment of the catheter of the present invention is illustrated in Fig. 5. In this embodiment, me catheter comprises a plurality of dehvery conduits 90 extending from the distal end 22 over expansion member 28 to me proximal end (not shown) of cadieter shaft 20. Dehvery conduits 90 have orifices 34 O on a lateral surface thereof opposite expandable member 28. Dehvery conduits 90 will be fastened at distal end 22 and to die exterior of catheter shaft 20, but will be unattached to expansion member 28. This permits dehvery conduits 90 to be displaced as expansion member 28 is inflated, witiiout creating stress concentrations on the surface of expansion member 28 as might be created by direct attachment of the conduits tiiereto. Furthermore, expansion member 28 may be compliant. Catheter shaft 20 and expansion member 28 will otherwise be substantially similar to those of Figs 1A-1E or 3A-3C. Dehvery conduits 90 may be manifolded at d e proximal end of die catheter as in the embodiment of Figs. 1A-1E, or connected to separate agent introduction ports as in Figs. 3A-3C for directional infusion. The invention as embodied in Fig. 5 provides a cadieter of very simple, low-cost construction widi independent infusion and expansion as well as directional infusion capabilities. Figure 6 illustrates a further embodiment of d e cadieter of d e present invention. The catheter includes a body 20 having an expansion member 28 near its distal end 22, a guidewire lumen 44 extending dirough die body 20, and a plurality of dehvery passages 36 integrated widi body 20 in a longitudinal direction. In this embodiment, a proximal infusion array 30a is disposed on die cadieter shaft proximal to expansion member 28, while a distal infusion array 30b is disposed on die cadieter shaft distally of expansion member 28. Infusion arrays 30a, 30b include a plurality of orifices 34 disposed on a lateral surface of dehvery conduits 32, which are in fluid connection widi dehvery passages 36. Distal portion of cadieter body 20 distally of expansion member 28 may be of reduced diameter to facihtate positioning in a vessel. In this embodiment, the cadieter of die present invention facilitates dilatation using expansion member 28, while infusing an agent through infusion arrays 30a, 30b. Infusion may be performed independendy of dilatation, permitting infusion of the agent before, during, after, or without dilatation. Further, as in other embodiments, each dehvery passage 36 and dehvery conduit 32 combination is independent of each od er, so as to facihtate directional infusion and/or infusion of two or more different agents simultaneously. It is also understood that d e cadieter may include only one of either distal infusion array 30b or proximal infusion array 30a, and tiiat orifices 34 may be included only on selected ones of dehvery conduits 32. Further, die cadieter may comprise, in addition to infusion arrays 30a and/or 30b, an infusion array about the periphery of the expansion member in the manner described above wid reference to Figs. 1-3. Catheters constructed in accordance widi die principles of the present invention may optionally be modified to provide for perfusion or by-pass blood flow, as generally described in U.S. Patent Nos. 4,661 ,094, and 4,892,519, d e disclosures of which are incorporated herein by reference. Generally, such perfusion flow can be provided by one or a series of perfusion ports on the proximal side of die expansion member 28, which ports permit the flow of blood into the shaft core 46 and eventually out through the distal opening of said core. In tiiis way, blood flow can be maintained even when d e expansion member 28 is expanded and would (in the absence of die perfusion capability) block blood flow. It should be understood that d e cadieter of d e present invention is suitable for dehvery of a variety of therapeutic agents including pharmaceuticals, proteins, peptides, nucleotides, carbohydrates, polysaccharides, muccopolysaccharides, simple sugars, glycosaminoglycans and steroids. The present invention facilitates dehvery of such agents in a variety of formulations, including aqueous vehicle or hposome. The drug dehvery cadieter is further useful for dehvery of viral particles to facihtate gene transfer. The agents dehvered may perform a variety of functions, including antithrombotics, antiplatelets, antimetabohcs, growth factor inhibitors, growth promoters, anticoagulants, antimitotics, and antibiotics. In a further embodiment, illustrated in Figs. 9-17, the agent infusion catheter is configured to shdably receive a conventional dilatation catheter within an axial guide passage in d e infusion catheter shaft. This allows the dilatation cadieter to serve as a guide wire for the infusion catheter to guide die cadieter to the treatment site, facilitates dilatation of a stenotic vessel independently of agent infusion, and permits the use of any of a variety of commercially-available dilatation catheters in conjunction widi die agent infusion catheter of the invention. Dilatation catheters suitable for use with d e infusion catheter illustrated in Figs. 9-17 are described, for example, in U.S. Patent No. 5,041 ,089, U.S. Patent No. 4,323,071 , U.S. Patent No. 4,292,974, U.S. Patent No. 4,762,129 and U.S. Patent No. 4,775,371, the complete disclosures of which are incorporated herein by reference. Such dilatation catiieters are commerciaUy available from, for example, Advanced Cardiovascular Systems, Inc., of Santa Clara, California. Referring to Fig. 9, in a preferred embodiment, agent infusion catheter 200 includes an elongate flexible shaft 202 having a distal end 204 and a proximal end 206. A manifold assembly 208 is fixed to d e proximal end of die shaft and includes dilatation cadieter port 210 on its proximal end and an agent introduction port 212 in a fitting 214 provided widi a Luer lock (not shown), secured to the assembly. At die distal end of d e shaft 202 is an infusion array 216 having a plurality of orifices 218 along lateral surfaces of the shaft. Shaft 202 comprises a plurality of axially disposed agent dehvery passages 220 extending from the proximal end which are connected to a corresponding number of agent dehvery conduits 222 at die distal end. Orifices 218 are in communication widi interior axial lumens 233 in dehvery conduits 222. An axial cut or slot 224 is formed in shaft 202 between each of dehvery conduits 222 such tiiat die delivery conduits are separated from one anotiier by the slots. A stiffening element 226 is disposed in at least a single dehvery conduit 222, as described more fully below. A conically tapered distal tip 228 is fixed to die distal end 204 of die shaft. In a preferred embodiment, shaft 202 will be constructed of materials and will have dimensions selected as appropriate for insertion of die shaft transluminally inside a guiding catheter (not shown), in a blood vessel. In an exemplary embodiment, shaft 202 will have a length in the range of 110 to 150cm, and an outer diameter of l .lmm-2.3mm (0.04 to 0.09 inches). Infusion array 216 will be approximately 10 to 60 mm in length. Catheter shaft 202 may be any of a variety of biocompatible, flexible materials including, for example, polyester, polyethylene or polyamide. Preferably, as described above, cadieter shaft 202 (including dehvery passages 220) and dehvery conduits 222 will comprise a single, monohdiic extrusion from proximal end 206 to distal end 204. As shown in Fig. 10A, in an undeployed configuration, infusion array 216 is aligned widi and has an outer diameter generally equal to that of die proximal portion of shaft 202. As shown in Fig. 10B, a dilatation catheter 230 may be positioned through an axial guide passage of shaft 202 (described below) such tiiat a balloon or other expansion member 232 at the distal end of the dilatation catheter is within infusion array 216 adjacent dehvery conduits 222. By expanding balloon 232, infusion array 216 is deployed radially outward to bring orifices 218 adjacent to a treatment site on a vessel wall. Fig. 11 illustrates a transverse cross-section through a proximal portion of shaft 202. A guide passage 234 extends longitudinally dirough the catheter shaft for shdably receiving a dilatation cadieter. Guide passage 234 may be coated with a lubricious material such as a hydrogel or fluorocarbon polymer, for example, fluorinated ethylene-propylene or poly tetrafluoroethylene, available commerciaUy under die trademark Teflon ® from DuPont. Such a coating facUitates longitudinal positioning and alignment of a dilatation catheter in guide passage 234 when cadieter 200 is disposed in a tortuous configuration in a vessel. Guide passage 234 wiU have a diameter of 0.7-2.0mm (0.03-0.08 inches), preferably 1.2-1.8mm (0.05-0.07 inches), suitable for receiving most commercially-avaUable dilatation catheters in current use. Dehvery passages 220 run paraUel to guide passage 234. In an exemplary embodiment, dehvery passages 220 are disposed in longitudinal ribs 236 which protrude radially outward from shaft 202. Dehvery passages 220 wiU have an interior height (or diameter, if round) in die range of 0.01mm to 0.7mm (0.005-0.03 inches). Figs. 12A-12E iUustrate transverse cross-sections of d e distal portion of shaft 202 dirough infusion array 216 in various embodiments. In the embodiment of Fig. 12A, dehvery conduits 222 are separated from each other by slots 224 so as to permit lateral expansion for deployment of die dehvery conduits. Dehvery conduits 222 have an axial lumen 238 which is in communication with delivery passages 220 in the catheter shaft. Dehvery conduits 222 surround guide passage 234. Stiffening elements 226 are disposed witiiin axial lumen 238 and occupy only a portion thereof to permit flow of agent through the lumen. In the embodiment of Fig. 12A, stiffener elements 226 comprise ribbon or bar-shaped rods of generally rectangular cross- section. The rods may be unrestrained in die axial lumens of die dehvery conduits, secured at their distal end to d e distal tip as described below, or co-extruded in the walls of the dehvery conduits, also described below. Stiffener elements 226 may be any of a variety of materials such as stainless steel, tantalum, nickel-titanium, or tungsten and having a geometrical configuration leading to greater axial rigidity but being laterally more flexible and resihent. The stiffening elements may extend from distal end 204 to proximal end 206 of shaft 202 through the dehvery passages, or may have a shorter length, e.g. 30-70 mm, so as to extend from a point near distal end 204 to a point just proximal to infusion array 216. Stiffener elements 226 serve several functions. First, d e stiffener elements help to maintain the patency of axial lumens 238 in the dehvery conduits. Second, stiffener elements 226 provide stiffness and resilience to dehvery conduits 222 such tiiat, following expansion of the dehvery conduits, they will recoil back to the undeployed configuration. Third, stiffener elements 226 serve to maintain the relative alignment between the dehvery conduits during longitudinal positioning and later expansion, so that d e dehvery conduits remain approximately equaUy separated from each otiier when deployed, facilitating uniform treatment of an area of the vessel waU. Furthermore, a stiffener element 226 of rectangular cross-section aUows controlling the relative magnitude of lateral versus radial stiffness. In the configuration shown, the bending stiffness of stiffener element 226 is substantiaUy less in the radial direction about a first axis perpendicular to die shaft tiian in the lateral direction about a second axis perpendicular to d e shaft and perpendicular to die first axis. Fig. 12B iUustrates a further embodiment of dehvery conduits 222 and stiffening elements 226. In this embodiment, slot 224 is significantly wider tiian in previous embodiments, such that substantiaUy ah of d e material between dehvery conduits 222 is removed. Further, in this embodiment, stiffener elements 226 comprise rods having a round cross-section. Widi such a shape, the stiffener elements are particularly effective in maintaining the patency of axial lumen 238. Further, die stiffener elements of round cross-section wiU not tend to block passage of an agent dirough orifices 218 if the rods float to d e outer surface of the axial lumen. In the embodiment of Fig. 12C, stiffener elements 226 comprise rods round in cross-section embedded in the outer waU 240 of dehvery conduit 222. It should be understood tiiat stiffener elements of various cross-sectional shapes may be embedded in the waU of the dehvery conduits in the manner shown in Fig. 12C. In the embodiment of Fig. 12D, stiffener elements 226 are disposed exterior to dehvery conduits 222. In an exemplary embodiment, the stiffener elements are disposed along a side surface of each dehvery conduit so as not to interfere with contact between the outer lateral surfaces of the dehvery conduits and d e waU of die vessel. Again, stiffener elements of various configurations may be used, including round, rectangular, and other cross-sectional shapes. In Fig. 12E, several additional embodiments of stiffener elements 226 are Ulustrated. In these embodiments, the stiffener elements have a surface contour which prevents the stiffener elements from blocking flow of agent through orifices 218 should d e stiffener elements float outward against the outer waU of the axial lumen. In one embodiment, stiffener element 226a has a zig-zag cross-section. In a second embodiment, stiffener element 226b has a double curve or wave cross-section. In a third embodiment, stiffener element 226c has a longitudinal ridge 242. In these embodiments, a plurality of transverse slots (not shown) may be provided at various points along the length of the stiffener elements to reduce radial stiffness and enhance the free flow of agent from one side of die stiffener element to the other. In another exemplary embodiment, Ulustrated in Fig. 12F, stiffener elements 226 wiU have a plurality of cut-outs 227 along their length, which may take the form of indentations along die longitudinal edges as shown, or, alternatively, slots or holes through a middle portion of the stiffener elements. Cut outs 227 facihtate flow of agent from one side of die stiffener elements to the other to ensure the agent is not blocked from flowing through orifices 218. In a further embodiment of infusion array 216, Ulustrated in Figs. 13 and 14A, an elastomeric sleeve 248 is mounted in guide passage 234, widi dehvery conduits 222 disposed about the periphery of the elastomeric sleeve. Elastomeric sleeve 248 wiU comprise a tubular element of a flexible and resilient elastomeric polymer, such as sihcon or uretiiane. UsuaUy, dehvery conduits 222 wiU be fixed to the exterior of elastomeric sleeve 248. In this way, die elastomeric sleeve serves to facilitate resihent return of the dehvery conduits from the deployed to d e undeployed position. In addition, the elastomeric sleeve serves to maintain alignment of the dehvery conduits as they are expanded so as to maintain proper spacing between adjacent dehvery conduits. Whtie stiffener elements 226 are included in Figs. 13 and 14, the use of elastomeric sleeve 248 may obviate die need for stiffening elements, as the sleeve may adequately maintain alignment and provide resUience. In an alternative embodiment, Ulustrated in Fig. 14B, elastomeric sleeve 248 is disposed external to dehvery conduits 222, wid d e dehvery conduits secured to d e interior of the sleeve. Orifices 218 extend from axial lumen 238 through dehvery conduits 222 as weU as dirough elastomeric sleeve 248. In a preferred embodiment, die elastomeric sleeve is configured so as to generaUy conform to the exterior contour of the dehvery conduits, minimizing the profile of the distal portion of the catheter, as weU as accommodating die expansion of d e dehvery conduits. Referring now to Figs. 15A-15C, distal tip 228 wiU be more fuUy described. Distal tip 228 provides a minimaUy traumatic leading edge to cadieter 200, as weU as facUitates shdable tracking of catheter 200 over a dUatation cadieter, as described more fuUy below. In addition, the distal tip 228 provides a seal for the distal ends of dehvery conduits 222. In an exemplary embodiment, shown in Figs. 15A-15B, distal tip 228 has an axial passage 250 aligned widi guide passage 234 in shaft 202. Distal tip 228 has a conicaUy tapered exterior to enhance navigation of the catheter through a vessel lumen. UsuaUy, distal tip 228 wtil have a length of 1 to 5mm and exterior diameter at proximal end 254 generaUy equal to that of d e outer surface of the dehvery conduits 222, wid distal end 252 being approximately 30% smaUer in diameter an proximal end 254. Distal tip 228 further includes a plurality of proximaUy-extending prongs 260, which fit within axial lumens 238 at the distal ends of dehvery conduits 222. Prongs 260 tiiereby provide a seal for the distal end of the dehvery conduits and provide the adhesion to shaft 202 required to properly retain distal tip 228 with the catheter. Prongs 260 can also be employed to retain the distal ends of stiffener elements 226 within axial lumens 238. In one embodiment, distal tip 228 may be molded uretiiane, formed by a process in which urethane is poured into a mold and the distal end of shaft 202 is inserted into the mold whUe the uretiiane is liquid, permitting the urethane to wick into axial lumens 238, thereby forming prongs 260. In an alternative embodiment of die distal tip, Ulustrated in Fig. 15C, distal tip 228 has a trumpet shape wherein axial passage 250 tapers radiaUy outward in the distal direction. The outer periphery of distal tip 228 may be tapered inward near d e distal end 252 to facihtate navigation through a vessel lumen. The trumpet-shaped distal tip of Fig. 15C facUitates smooth retraction of the expansion member (e.g. baUoon) of a dUatation cadieter from a position distal to distal tip 228 to a position witiiin guide passage 234 adjacent dehvery conduits 222. Fig. 15C further iUustrates die retention of distal ends 229 of stiffener elements 226 by encapsulation in prongs 260 of the distal tip. In this embodiment, when distal tip 228 is to be formed, stiffener elements 226 are positioned in axial lumens 238 of the dehvery conduits with distal ends 229 near d e distal end 204 of shaft 202. Distal tip 228 is then formed as described above, by pouring a polymer such as urethane into a mold and putting the distal end of die catheter shaft in the mold whUe the urethane is hquid. The uretiiane tiien wicks into axial lumens 234, encapsulating the distal ends of the stiffener elements. Referring now to Fig. 16, manifold assembly 208 wiU be more fuUy described. The manifold assembly includes a housing 262 which may be a metal or any of a variety of rigid plastics, including acrylonitrile-butadiene-styrene (ABS), Delrin ® , polycarbonate and the like. Shaft 202 extends through a flexible polymeric strain relief 264 into an interior chamber 266 within housing 262. The proximal end 270 of shaft 202 is secured about a cylindrical mandrel 272 formed in housing 262. Mandrel 272 has an axial bore 274 which connects dUatation catheter port 210 to guide passage 234. In a preferred embodiment, a diaphragm 275 is mounted in a proximal portion of bore 274 near catheter port 210. Diaphragm 275 has a passage 277 which may comprise a hole or sht which elastically expands when a dUatation catheter of larger diameter is inserted dirough it. The diaphragm thus provides a sealed entrance for introducing a dUatation cadieter into guide passage 234. Chamber 266 is in communication wid agent introduction port 212 in Luer fitting 214. The proximal end of shaft 202 wiU have circumferential notches 268 providing fluid communication between chamber 266 and agent dehvery passages 220. Luer fitting 214 wUl be configured for connection to a precision agent dehvery device. In this way, an agent dehvered dirough dehvery port 212 wUl flow into dehvery passages 220 for dehvery to infusion array 216. In a preferred embodiment of the metiiod of the present invention, Ulustrated in Figs. 8 A and 8B, the catheter is positioned transluminaUy in a body lumen or vessel V, which wiU typicaUy be an artery. The vessel wiU have a waU comprising three layers, including intima I, media M and adventitia A. The catheter wiU be positioned such tiiat orifices 34 in dehvery conduits 32 are disposed near die treatment site, which wiU most often be an atherosclerotic region of stenosis S in the artery. UsuaUy, a movable guide wire 26 wiU be used to guide d e catheter through the artery. A fixed guidewire attached to d e distal end 22 of the catheter may be used instead. When the cadieter has been positioned near d e treatment site S, the expansion member 28 is inflated with an inflation fluid introduced through inflation fluid introduction port 42 in housing 38 at the proximal end of die catheter. Preferably, expansion member 28 is expanded sufficientiy to bring dehvery conduits 32 into contact with d e treatment site S. If desired, dUatation of d e vessel may be performed by inflating expansion member 28 sufficiently to expand the interior of the vessel lumen in the region of stenosis so as to effectively restore blood flow to an appropriate level. Frequently, it wUl be desirable to impregnate die treatment site S with an agent before, during or after such dUatation. Advantageously, die physician may position the dehvery conduits 32 against the treatment site and perform any desired dUatation without infusing any agent through orifices 34 in conduits 32. When agent dehvery is desired, an agent is introduced dirough agent introduction port 40 in proximal housing 38, from which it is communicated dirough dehvery passages 36 to dehvery conduits 32. The agent wUl be infused dirough orifices 34 to penetrate the treatment site S. UsuaUy, the agent wUl be infused into the treatment site at pressures sufficient to attain penetration to at least the media M, and preferably into the adventitia A of d e vessel. In an alternative method, an agent may be infused into the lumen before expanding the expansion member. After infusion, or whUe it is continuing, an inflation fluid may be introduced into the device to expand die expansion member, positioning die dehvery conduits adjacent d e lumen waU. Infusion of the agent may continue, or a different agent may be infused dirough die dehvery conduits to penetrate a treatment site within the lumen waU. In a specific embodiment, die method may comprise infusing an agent through one or more selected dehvery conduits 32 without infusing the agent through other selected dehvery conduits. Using the catheter Ulustrated in Figs. 3A-3C, die agent wUl be introduced dirough one or more agent introduction ports 140 connected to die dehvery conduits 32 which are to be used for infusion. For example, in Figs. 8A and 8B, an agent may be infused dirough dehvery conduits 32a, 32b, but not through dehvery conduit 32c, by introducing d e agent through the corresponding introduction ports 140 at the proximal end of die cadieter. In a further embodiment, die method may include infusing a first agent through selected ones of dehvery conduits 32 whUe infusing one or more different agents through otiiers of delivery conduits 32. Referring to Figs. 8A and 8B, a first agent, such as a growth inhibitor, may be infused through dehvery conduit 32c, whUe infusing a second agent, such as an anticoagulant, dirough dehvery conduits 32a, 32b. This is accomphshed by introducing die first agent through the appropriate introduction port 140 (Fig. 3 A) connected to conduits 32a, 32b, whUe introducing the second agent dirough die introduction port 140 connected to dehvery conduit 32c. Once treatment at a particular site has been completed, drug dehvery may be terminated, and, if desired, expansion member 28 deflated by witiidrawing the expansion fluid dirough inflation passage 54. Dilatation and/or agent infusion may be repeated at d e treatment site S. When treatment of d e site is complete, the catheter may be repositioned without removing it from the body to perform dUatation and/or agent infusion at a new treatment site. It can be seen that the device and method of die present invention facihtate infusion of an agent with or without dUatation, dUatation with or witiiout infusion, infusion of multiple agents simultaneously, directional infusion, and treatment of multiple sites, without removing the device from the body between such treatments. A further embodiment of d e metiiod of the invention is Ulustrated in Figs. 17A-17D. In this embodiment, utilizing the agent infusion catheter 200 described above in connection with Figs. 9-16, a baUoon dUatation catheter DC of conventional construction is transluminaUy positioned in a blood vessel V such tiiat a baUoon or other expansion member 280 (in an uninflated configuration) is near a treatment site S. TypicaUy, dUatation catheter DC wiU be positioned over a movable flexible guide wire GW. During this step, agent infusion catheter 200 need not be, but may be, positioned shdably over dUatation catheter DC. In some embodiments, it would be desirable to position a dUatation catheter in the vessel first, do a dUatation and tiien remove d e dUatation catheter. Subsequently, catheter 200 is introduced over die dUatation catheter and both catiieters are introduced togetiier into the vessel. In other instances, catheter 200 wtil be positioned over d e dUatation catheter outside of d e body, and both catheters wiU be transluminaUy positioned in the vessel togetiier. The dUatation O catheter may then be used to perform dUatation as described below. As shown in Fig. 17B, baUoon dUatation cadieter DC is positioned such tiiat expansion member 280 is disposed distal to d e distal end of agent infusion catheter 200. Expansion member 280 is then inflated using known techniques, dUatating vessel V at treatment site S. Expansion member 280 is men deflated and, as shown in Fig. 17C, dUatation cadieter DC is drawn proximaUy relative to agent infusion catheter 200. Dilatation catheter DC is positioned such that expansion member 280 is adjacent infusion array 216 in the interior guide passage of catheter 200, described above. Agent infusion catheter 200 is then positioned witiiin vessel V such that infusion array 216 is near treatment site S. Expansion member 280 is then inflated so as to position dehvery conduits 222 in apposition to treatment site S on the vessel waU. An agent is then dehvered dirough dehvery passages 220 in catheter 200 to dehvery conduits 222. The agent is infused under pressure dirough die dehvery conduits and through orifices 218 to penetrate the vessel waU in the region of treatment site S. When treatment is complete at the site, agent dehvery is discontinued, and expansion member 280 deflated to return dehvery conduits 222 to an undeployed position as in Fig. 17C. If further treatment is desired at die same or different site, dUatation catheter DC may be extended distal to infusion catheter 200 to the position shown in Fig. 17 A. DUatation and/or agent infusion may be repeated at die same or a different site. To facUitate longitudinal positioning of infusion catheter 200 in a vessel lumen, as weU as to assist proper axial alignment of the expansion member (e.g. baUoon) of the dUatation cadieter widi infusion array 216, radiopaque markers may be provided on infusion catheter 200. In a preferred embodiment, shown in Figs. 18A- 18C, radiopaque markers 282 are disposed on one or more of stiffener elements 226. Markers 282 are formed by, for example, plating a radiopaque material such as gold or platinum onto stiffener elements 226. DUatation catheter DC wiU also have a radiopaque marker 284, which is typicaUy formed on the inner shaft 286 of catheter DC in the interior of expansion element 280. In one embodiment, shown in Fig. 18 A, at least two markers 282 are disposed on stiffener elements 226 in a central portion of infusion array 216, the markers being separated a distance from one another usuaUy about equal to or slightly greater than the length of marker 284 on dUatation catheter DC. In this way, by visualization through a radiographic imaging device, markers 282 facihtate axial alignment of expansion element 280 with infusion array 216 by aligning dUatation cadieter marker 284 between markers 282 on stiffener elements 226. Markers 282 further provide visual indication of d e location of infusion catheter 200 within the vessel so that infusion array 216 may be positioned adjacent to a treatment site. Alternative embodiments of radiopaque markers 282 are Ulustrated in Figs. 18B and 18C. In Fig. 18B, marker 282 is disposed on a distal portion of stiffener element 226. In this way, dUatation cadieter DC and/or infusion catheter 200 are axiaUy re-positioned relative to one another until marker 284 on the dUatation catheter is exposed on d e proximal side of marker 282. In the embodiment of Fig. 18C, marker 282 is disposed on a proximal portion of stiffener element 226 whereby the catheters are axiaUy aligned by positioning dUatation cadieter marker 284 distal to marker 282 on the stiffener element. WhUe the above is a complete description of die preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, die above description should not be taken as limiting the scope of die invention which is defined by die appended claims.

Claims: WHAT IS CLAIMED IS: 1. A method of delivering an agent to a treatment site on an interior waU of a blood vessel, die meti od comprising: positioning a catheter in the blood vessel wid an infusion array at the distal end of d e cadieter near the treatment site; expanding an expansion member at the distal end of the catheter to position the infusion array adjacent to the treatment site, the expansion member being fluidly isolated from the infusion array; thereafter, delivering an agent to die infusion array; and infusing the agent into the treatment site through a plurality of orifices in the infusion array. 2. A method as in claim 1 wherein the infusion array comprises a dehvery conduit disposed adjacent a lateral surface of the expansion member, the orifices disposed on a surface of die dehvery conduit. 3. A method as in claim 2 wherein the infusion array further comprises a plurality of dehvery conduits disposed adjacent lateral surfaces of the expansion member. 4. A method as in claim 3 wherein the agent is dehvered through a plurality of separate dehvery passages such tiiat dehvery of d e agent to each dehvery conduit may be controUed independently. 5. A method as in claim 4 wherein an agent is infused dirough a selected dehvery conduit witiiout infusing the agent through at least one other dehvery conduit. 6. A method as in claim 4 wherein a first agent is infused dirough a first dehvery conduit whtie a second agent is infused dirough a second dehvery conduit. 7. A method as in claim 1 wherein die expansion member is attached to a dUatation device removably disposed in an axial passage in the catheter, the method further comprising the step of positioning the dUatation catheter in the axial passage. 8. A method as in claim 1 wherein the step of positioning the catheter in the blood vessel comprises guiding d e catheter into the vessel using a guidewire. 9. A method as in claim 1 wherein d e treatment site comprises a atherosclerotic region of me blood vessel. 10. A method as in claim 9 further comprising expanding d e expansion member to dUatate die vessel. 11. A method as in claim 10 wherein the step of dUatating is performed before die step of infusing. 12. A method as in claim 10 wherein the step of dUatating is performed after the step of infusing. 13. A method as in claim 10 wherein the step of dUatating is performed during the step of infusing. 14. A method of delivering an agent to a treatment site on a waU of a biliary duct, d e metiiod comprising: positioning an agent dehvery cadieter in the biliary duct wid an infusion array at the distal end of die cadieter near the treatment site; expanding an expansion member coupled to die infusion array to position the infusion array adjacent to the treatment site, the expansion member being fluidly isolated from the infusion array; thereafter, delivering an agent to the infusion array; and infusing the agent into the treatment site through a plurality of orifices in the infusion array. 15. A method of delivering an agent to a treatment site in a lumen of the genital-uretal system, the metiiod comprising: positioning an agent dehvery catheter in the lumen with an infusion array at the distal end of the catheter near the treatment site; expanding an expansion member coupled to die infusion array to position the infusion array adjacent to die treatment site, the expansion member being fluidly isolated from the infusion array; thereafter, delivering an agent to the infusion array; and infusing the agent into the treatment site through a plurality of orifices in the infusion array. 16. Apparatus for infusing an agent to a treatment site on a waU of a body lumen, the apparatus comprising: a catheter body having a distal end, a proximal end and first and second passages d erebetween; a guidewire extending from the distal end of die cadieter body; an expansion member disposed at the distal end of d e catheter body, die interior of the expansion member being in fluid communication widi die first passage; and an infusion array fluidly isolated from the expansion member and disposed adjacent to a lateral surface thereof so as to be positionable adjacent to die treatment site by expansion of the expansion member, the infusion array comprising at Oleast one dehvery conduit having a plurality of orifices on a surface thereof and an axial lumen connecting the orifices to the second passage in the catheter body. 17. The apparatus of claim 16 wherein the infusion array further comprises a plurality of said dehvery conduits disposed about the periphery of the expansion member. 18. The apparatus of claim 17 wherein the catheter body further includes a plurahty of independent dehvery passages extending between the distal and proximal ends, each of die dehvery passages being in communication wid one of die dehvery conduits. 19. The apparatus of claim 18 further comprising a manifold at d e proximal end of d e cadieter body, die manifold being in fluid communication with each of said dehvery passages and connectable to an agent dehvery source. 20. The apparatus of claim 18 wherein an agent may be infused dirough a selected dehvery conduit witiiout infusing the agent through others of die dehvery conduits. 21. The apparatus of claim 20 wherein a first agent may be infused dirough a first dehvery conduit whUe a second agent is infused through a second dehvery conduit. 22. The apparatus of claim 21 wherein each dehvery passage includes means at the proximal end for independently introducing an agent into the dehvery passage. 23. The apparatus of claim 16 wherein the expansion member is attached to a second cadieter removably disposed in an axial passage in the catheter body. 24. The apparatus of claim 23 wherein the infusion array is mounted on an expandable support member attached to d e catheter body such tiiat the expansion member engages the support member to position the infusion array adjacent to die treatment site. 25. The apparatus of claim 16 wherein die cadieter body, expansion member and infusion array comprise a single monohdiic extrusion. 26. The apparatus of claim 16 wherein the guidewire comprises a movable guidewire, the cadieter body further having a guidewire passage through which the movable guidewire is shdably disposed. 27. The apparatus of claim 16 wherein the infusion array infuses the agent into d e treatment site at a pressure sufficient to penetrate to an adventitial layer of the body lumen. 28. Apparatus for infusing an agent in a body lumen, die apparatus comprising: a catheter body having a distal end, a proximal end and an inflation passage and a plurahty of independent dehvery passages extending dierebetween; an expansion member attached to die cadieter body near d e distal end, d e interior of die expansion member being in fluid communication with the inflation passage; a plurahty of dehvery conduits disposed about die periphery of d e cadieter body near die distal end, each dehvery conduit in communication with one of the dehvery passages, wherein at least a portion of the dehvery conduits are fluidly independent of otiiers of the dehvery conduits so as to be individuaUy supphed widi an agent through the dehvery passages; and a plurahty of orifices on a lateral-facing surface of the dehvery conduits for infusing the agent into the lumen. 29. The apparatus of claim 28 wherein the orifices are disposed on a portion of d e dehvery conduits adjacent die periphery of the expansion member. 30. The apparatus of claim 28 wherein the orifices are disposed on a portion of the dehvery conduits distally of the expansion member. 31. The apparatus of claim 28 wherein the orifices are disposed on a portion of the dehvery conduits proximal to the expansion member. 32. The apparatus of claim 28 wherein the catheter body, dehvery conduits and expansion member comprise a single monohdiic extrusion. 33. Apparatus for infusing an agent to a treatment site on the waU of a body lumen, the apparatus comprising: a flexible shaft having a distal end and a proximal end, widi a guide passage and at least one dehvery passage extending axiaUy through the shaft, the guide passage being open at the distal end; an inflation tube shdably disposed in the guide passage having a distal end, a proximal end, an axial inflation lumen therebetween, and an expansion member attached to die distal end in communication with the inflation lumen, wherein the expansion member may be advanced distaUy from the distal end of the shaft; and a plurahty of lateraUy-deflectable dehvery conduits attached to the distal end of die shaft generaUy paraUel tiiereto, each dehvery conduit having an axial lumen in communication with at least one of die dehvery passages and a plurahty of orifices on a lateral surface thereof, wherein the expansion member is axiaUy positionable adjacent to die dehvery conduits for lateraUy positioning die dehvery conduits in apposition to the treatment site. 34. The apparatus of claim 33 further comprising a plurahty of fluidly independent dehvery passages in the shaft, wherein at least a first of the dehvery conduits is in communication with a different dehvery passage tiian at least a second of d e dehvery conduits so as to aUow independent dehvery of agents to the first and second dehvery conduits. 35. The apparatus of claim 33 further comprising means for maintaining relative ahgnment of the dehvery conduits during lateral deflection tiiereof. 36. The apparatus of claim 35 wherein the means for maintaining ahgnment resUiendy biases the dehvery conduits to an undeflected configuration. 37. The apparatus of claim 35 wherein the ahgnment maintaining means comprises a tubular elastomeric sleeve, the dehvery conduits being secured to die sleeve. 38. The apparatus of claim 37 wherein the elastomeric sleeve is disposed interior to the dehvery conduits, die dehvery conduits being secured to an exterior surface of the sleeve. 39. The apparatus of claim 37 wherein the elastomeric sleeve is disposed exterior to the dehvery conduits, the delivery conduits being secured to an interior surface of the sleeve, wherein the orifices extend from d e axial lumens of the dehvery conduits through the sleeve. 40. The apparatus of claim 35 wherein the ahgnment maintaining means comprises a stiffening element disposed axiaUy in at least one dehvery conduit. 41. The apparatus of claim 40 wherein the stiffening element comprises an axiaUy rigid, lateraUy flexible rod. 42. The apparatus of claim 41 wherein the stiffening element has a geometry selected to provide low bending stiffness about a first axis perpendicular to d e shaft, but high bending stiffness about a second axis perpendicular to the shaft and perpendicular to die first axis. 43. The apparatus of claim 41 wherein the rod is a resihent metal. 44. The apparatus of claim 40 wherein the stiffening element is embedded in the waU of the dehvery conduit. 45. The apparatus of claim 40 wherein the stiffening element is disposed in die axial lumen of the dehvery conduit. 46. The apparatus of claim 40 wherein the stiffening element is secured to the exterior of the dehvery conduit. 47. The apparatus of claim 40 wherein at least a portion of stiffening element is radiopaque. 48. The apparatus of claim 33 further comprising means for maintaining patency of the axial lumen of each dehvery conduit. 49. The apparatus of claim 48 wherein the means for maintaining patency comprises a flexible rod disposed axially in the axial lumen of at least one of die dehvery conduits. 50. The apparatus of claim 49 wherein the rod is a resihent metal. 51. The apparatus of claim 33 further comprising a flexible distal tip having a proximal end secured to d e distal end of d e shaft, an open distal end, and an axial passage between the proximal and distal ends aligned widi d e guide passage of die cadieter. 52. The apparatus of claim 51 wherein the distal tip is conicaUy tapered such tiiat d e distal end has a smaUer diameter than the proximal end. 53. The apparatus of claim 51 wherein the axial passage of the distal tip is conicaUy tapered such that the axial passage has a diameter at the open distal end which is larger than the diameter of the guide passage. 54. The apparatus of claim 51 wherein the distal tapered tip is made of a polymer with a durometer of 30 Shore A to 50 Shore D. 55. The apparatus of claim 51 wherein the proximal end of die tapered tip comprises a plurahty of prongs extending proximaUy from the tip and received in the axial lumens of the dehvery conduits. 56. The apparatus of claim 55 further comprising at least one stiffening element disposed in me axial lumen of at least one dehvery conduit, a distal end of d e stiffening element being secured to one of said prongs of said distal tip. 57. The apparatus of claim 33 wherein the shaft, dehvery passage and dehvery conduits comprise a single monohdiic extrusion. 58. The apparatus of claim 57 wherein the dehvery conduits are separated from one another by axial slots in said extrusion. 59. Apparatus for infusing an agent to a treatment site on a waU of a body lumen, the apparatus comprising: a flexible shaft having a distal end, a proximal end and first and second passages dierebetween; an expansion member disposed at die distal end of die shaft, die interior of the expansion member being in fluid communication wid die first passage; at least one lateraUy-deflectable dehvery conduit secured at the distal end of d e shaft adjacent d e expansion member, d e dehvery conduit having a plurahty of orifices on a lateral surface thereof and an axial lumen connecting the orifices to die second passage in the shaft; and an axiaUy rigid stiffening element disposed axiaUy in the dehvery conduit. 60. The apparatus of claim 59 wherein die stiffening element comprises a rod embedded in a waU of die dehvery conduit. 61. The apparatus of claim 59 wherein me stiffening element comprises a rod disposed in the axial lumen of the dehvery conduit. 62. The apparatus of claim 59 wherein the stiffening element comprises a rod fixed to the exterior of the dehvery conduit. 63. The apparatus of claim 59 wherein tiie stiffening element is a resilient metal. 64. The apparatus of claim 59 wherein at least a portion of the stiffening element is radiopaque. 65. The apparatus of claim 64 further comprising a radiopaque marker fixed widi respect to the expansion member, the radiopaque portion of the stiffening element being disposed in a position selected to facUitate ahgnment of the expansion member adjacent to die dehvery conduit by positioning the radiopaque marker relative to the radiopaque portion of the stiffening element. 66. The apparatus of claim 59 further comprising: a guide passage between the proximal and distal ends of tiie shaft; and an inflation tube shdably disposed in the guide passage, d e inflation tube having a proximal end and a distal end, wherein the inflation lumen is disposed in the inflation tube and die expansion element is secured to the distal end of die inflation tube. 67. The apparatus of claim 66 wherein the guide passage has an open distal end such that the expansion member may be advanced distally from tiie distal end of d e shaft. 68. The apparatus of claim 59 further comprising a plurahty of said dehvery conduits arranged about die distal end of die shaft. 69. The apparatus of claim 68 further comprising means for maintaining ahgnment of the dehvery conduits during deflection diereof. 70. The apparatus of claim 69 wherein the means for maintaining ahgnment comprises a tubular elastomeric sleeve, the dehvery conduits being secured to a surface of the elastomeric sleeve. 71. The apparatus of claim 70 wherein the elastomeric sleeve is disposed interior to the dehvery conduits, the dehvery conduits being secured to an exterior surface of the sleeve. 72. The apparatus of claim 70 wherein the elastomeric sleeve is disposed exterior to the dehvery conduits, the delivery conduits being secured to an interior surface of the sleeve, wherein the orifices extend from die axial lumens of the dehvery conduits dirough the sleeve. 73. The apparatus of claim 68 further comprising a plurahty of independent dehvery passages from the proximal end to d e distal end of d e shaft, at least a first of the dehvery conduits being connected to a different dehvery passage than a second of die dehvery conduits so as to aUow independent dehvery of agents through the first and second dehvery conduits. 74. The apparatus of claim 59 wherein the shaft and dehvery conduits comprise a single monohdiic extrusion. 75. The apparatus of claim 74 wherein the dehvery conduits are separated from one another by axial slots in said extrusion. 76. The apparatus of claim 59 wherein the shaft, dehvery conduits and expansion member comprise a single monohdiic extrusion. 77. A method of delivering an agent to a treatment site on an interior waU of a blood vessel, the method comprising: positioning a first catheter in the blood vessel wid an expansion member at a distal end of d e first catheter near the treatment site; positioning a second cadieter over the first catheter such that the first catheter is shdably disposed in an axial passage in the second cadieter, whereby an infusion array at a distal end of die second cadieter is near die treatment site with d e expansion member of the first catheter positioned distal to the distal end of die second catheter; expanding the expansion member to dUatate die blood vessel at die treatment site; contracting the expansion member; axiaUy aligning both catheters such that the infusion array is aligned with the treatment site and die expansion member is adjacent to die infusion array; expanding die expansion member so as to position the infusion array adjacent to die treatment site; and infusing an agent into the treatment site through a plurahty of orifices in the infusion array. 78. The method of claim 77 wherein the infusion array comprises a plurahty of dehvery conduits secured to d e distal end of d e second cadieter, die dehvery conduits having axial lumens for delivering an agent dirough said orifices. 79. The method of claim 77 wherein the step of axiaUy aligning comprises aligning a radiopaque marker on the first catheter widi at least one radiopaque marker on the second cadieter. 80. The metiiod of claim 79 wherein the radiopaque marker on the second cadieter is disposed on a metallic stiffening element in the infusion array.

Inventors: KAPLAN AARON V, KERMODE JAMES R, KLEIN ENRIQUE J, KAPLAN, AARON, V., KERMODE, JAMES, R., KLEIN, ENRIQUE, J.
Applicants: LOCALMED INC, LOCALMED, INC.
Application year: 1993
Main classification: A61M29
IPC codes: A61B8, A61F2, A61M25, A61M29, A61M37