Local drug delivery injection catheter

[0002] This invention pertains to a catheter for delivering a drug to a specific location within a patient's artery.

[0003] It is known in the art to provide catheters for delivering drugs directly into the walls of a patient's artery. An example of such a catheter is described in U.S. Pat. No. 5,746,716, issued to Vigil et al. Vigil's catheter 1 includes a set of injectors 2 for injecting medication into an artery wall 3 (FIG. 1). Injectors 2 are mounted on a balloon 4 which is inflated when it is desired to push injectors 2 into artery wall 3. Unfortunately, injectors 2 extend in a direction perpendicular to the axis of catheter 1. Thus, when catheter 1 is inserted or withdrawn from the patient's vascular system, there is a danger that injectors 2 will drag along and injure artery wall 3.

[0004] What is needed is an improved catheter which permits delivery of a drug into the walls of an artery where the drug is believed to be most effective.

[0005] What is also needed is a catheter with injectors which will not drag across the artery walls when the catheter is inserted or withdrawn from a patient.

[0006] A catheter in accordance with an embodiment of the invention comprises an injection port at or near the distal end thereof and a mechanism for directing the injection port angularly away from the central axis of the catheter and into the artery wall. (An injection port is a structure used for introducing medication or other material into a patient. The injection port typically is a hollow needle.) In one embodiment, the catheter includes a guide wire lumen for receiving a guide wire that enables a physician to direct the catheter to a desired location within the patient's vascular system. Also, in one embodiment, the catheter includes a plurality of needles, each of which may be manipulated at an angle outwardly from the central longitudinal axis of the catheter so that the needles can inject a drug or medication into the surrounding tissue. Prior to deployment of the needles, the needles are retained such that they lie substantially parallel to the longitudinal axis of the catheter.

[0007] In one embodiment, a balloon is provided towards the distal end of the catheter for pushing the needles outwardly into the artery wall. In another embodiment, other mechanical means are provided for pushing the needles outwardly.

[0008] These and other features of the invention are described below.

[0009] FIG. 1 illustrates a prior art catheter for injecting medication into a patient's artery walls.

[0010] FIG. 2 illustrates in cross section a catheter constructed in accordance with the invention comprising needles for injecting medication into an artery wall.

[0011] FIG. 3 illustrates in cross section the catheter of FIG. 2 in which the needles are extended outwardly for injecting medication into the artery wall.

[0012] FIG. 3′ illustrates an enlarged portion of the catheter of FIG. 3.

[0013] FIG. 3A illustrates in cross section the catheter of FIGS. 2 and 3 along lines A—A.

[0014] FIG. 3B illustrates in cross section an alternative embodiment of a catheter along lines A—A in which a stiffening mandrel is provided external to two of the catheter tubes.

[0015] FIG. 3C illustrates a cut formed in a tube to accommodate placement of a needle.

[0016] FIG. 3D illustrates another cut formed in a tube to accommodate placement of a needle.

[0017] FIG. 4 illustrates another embodiment of a catheter including a balloon for pushing needles from the catheter outwardly into the artery wall.

[0018] FIGS. 4A, 4B and 4C illustrate in cross section the catheter of FIG. 4 along lines A—A, B—B and C—C, respectively.

[0019] FIG. 4D illustrates in cross section an alternative balloon used in conjunction with another embodiment of a catheter in accordance with the invention.

[0020] FIG. 4E illustrates another embodiment of a catheter including a balloon for pushing needles from the catheter outwardly into the artery wall.

[0021] FIG. 5 illustrates in cross section a modified embodiment of the catheter of FIG. 4 including a short balloon length with a steep proximal balloon wall.

[0022] FIG. 6 illustrates the distal end of a catheter including a helical balloon in accordance with another embodiment of the invention.

[0023] FIG. 7 illustrates a catheter in accordance with the invention in conjunction with a sheath.

[0024] Referring to FIGS. 2, 3 and 3′, a catheter 10 in accordance with an embodiment of the invention includes a proximal end 10p,a distal end 10dand a centrally located guide wire tube 29 having a lumen 12 for receiving a guide wire 14. Thus, prior to use, an attending physician can route guide wire 14 into the patient and insert catheter 10 over the guide wire to a desired location within the patient's vascular system. Once catheter 10 is in place, guide wire 14 extends through lumen 12 and out of a guide wire control port 16.

[0025] Also within catheter 10 is a drug delivery port 18 for receiving a drug to be injected into the patient. Drug delivery port 18 is connected to a drug delivery lumens 22a,22b.(In one embodiment, not shown, lumens 22aand 22bcan merge into a single lumen concentrically surrounding guide wire tube 29.)

[0026] Although FIGS. 2, 3, and 3′ illustrate two lumens 22a,22b,other numbers of lumens for delivering drugs can also be used, e.g., between two and four lumens. However, the invention is not limited by the exact number of drug delivery lumens 22.

[0027] A shrink tube 24 approximately 1 to 6 cm from distal end 10dof catheter 10 binds tubes 27a,27b(surrounding lumens 22a,22b) together. Shrink tube 24 is affixed to tube 27a,27b,but surrounds and can slide along guide wire tube 29. At a distance D1 from shrink tube 24, tubes 27a,27bare sliced around a circumferential portion of approximately 180°, and hollow needles 26a,26b,are inserted into lumens 22a,22brespectively. (The slice formed in tubes 27aand 27bcan have different shapes. FIGS. 3C and 3D illustrate two embodiments of slices 31a,31bthat can be formed in tubes 27aand 27bto accommodate needle placement. The slices 31a,31bhelp create a preferential bending position for tubes 27aand 27band are sized to facilitate needle placement.) Needles 26a,26bcan be held in place within lumens 22a,22b,for example, by an appropriate adhesive (e.g. cynoacrylate). Tubes 27a,27bcontinue distally of needles 26a,26b.Tubes 27a,27bterminate at distal end 10dof catheter 10, and are bound together and to guide wire tube 29 with second shrink tube 28. (Shrink tube 28 cannot move relative to tube 29.) Needles 26a,26bare typically located half way between shrink tube 28 and shrink tube 24. The very ends 27a′, 27b′ of tubes 27a,27bmay be open or sealed.

[0028] In one embodiment, shrink tubes 24 and 28 are located at preferential bending positions of tubes 27aand 27b.Because tubes 27a,27bare not bound to tube 29 along the entire length of catheter 10, this permits relative motion of portions of tubes 27a,27band tube 29. (As explained below, during use, moving tubes 27aand 27brelative to tube 29 pushes needles 26 outwardly into the artery wall or inwardly towards guide wire tube 29.) The fact that tubes 27a,27bare not rigidly bound to tube 29 by shrink tube 24 facilitates bending of the tubes 27a,27b.

[0029] Referring to FIG. 3, in accordance with the first embodiment of the invention, after catheter 10 is in its proper position within the patient's vascular system, a physician extends needles 26a,26boutwardly (in directions A and B, respectively) by sliding drug delivery port 18 in a forward direction (see arrow C) relative to guide wire control port 16.

[0030] A portion of catheter 10 is shown in greater detail in FIG. 3′. The movement of drug delivery port 18 relative to guide wire control port 16 causes a first body portion of catheter 10 comprising tubes 27aand 27bto move relative to a second body portion comprising tube 29. Portions P1, P2 and P3 of tube 27aand portions P4, P5 and P6 of tube 27bact as hinges, permitting needles 26a, 26bto move outwardly. In this way, needles 26a, 26bare pushed away at an angle α from the main axis of catheter 10 and into the artery wall of the patient.

[0031] In other words, during insertion and placement of catheter 10, needles 26a, 26band the portions of tubes 27a, 27bconnected to needles 26a, 26blie substantially parallel to guide wire 14 (i.e., α=0°). When the needles 26a, 26bare deployed, portions P1, P2 serve as axes of rotation for the needles 26a, 26band the portions of tubes 27a, 27bconnected to needles 26a, 26b.Needles 26a, 26bare rotationally pushed away such that portions of tubes 27a, 27bconnected to needles 26a, 26bthus form an angle α>0°. When deployed, needles 26a, 26bextend outwards from the main body of catheter 10 by a distance D4, thereby contacting the artery wall.

[0032] The attending physician can then inject medication through drug delivery lumens 22a,22band needles 26a, 26binto the wall of the patient's artery. Such medication can be, for example, an anti-inflammatory, anti-restenotic, or anti-thrombotic medication. Thereafter, the physician can retract needles 26 in directions D and E by pulling drug delivery port 18 in a direction F relative to guide wire control port 16. Catheter 10 can then be retracted from the patient.

[0033] In one embodiment, needles 26a, 26bare stainless steel, have an inner diameter of 0.002″ to 0.010″ and an outer diameter of 0.005″ to 0.014″, extend a distance D2 (FIG. 3) of 1 to 3 mm outside of tubes 27a, 27b, and have a total length of 3 to 8 mm. However, other needle sizes can also be used. Catheter 10 can be designed such that distance D4 is customized to facilitate better deployment into different size arteries, e.g. coronary or peripheral. Needles 26a, 26bcan be blunt, as shown in FIG. 3, or sharp.

[0034] The distance D3 (FIG. 2) between shrink tube 24 and the point where needles 26a, 26bexit from tubes 27a, 27bis between 2 to 10 mm. Distances D2 (FIG. 3) and D3 (FIG. 2) are chosen based on the caliber of the artery in which catheter 10 is to be used. The greater the artery caliber, the greater the total distance D2 plus D3. This is done to ensure that needles 26 reach the artery wall when they are outwardly extended.

[0035] In one embodiment, a catheter in accordance with the invention can be the length L1 (FIG. 2) of conventional balloon dilatation catheters, e.g., 40 to 200 cm. The sliding portion of catheter 10 can have a distance L2 (FIG. 2) between 35 and 195 cm. Shrink tube 28 can be a distance D4 (FIG. 2) between 2 and 30 mm from the distal end of catheter 10. However, other lengths and distances can also be used.

[0036] Stiffening mandrels 30a,30bcan be provided within lumens 22a,22bof tubes 27a, 27bas shown in FIGS. 2, 3, 3′, 3A and 3B. In one embodiment, the distal ends of mandrels 30a,30b(e.g. the distal 1 to 20 mm) can be flatter than the proximal ends of mandrels 30a,30b.Optionally, notches can be formed in stiffening mandrels 30aand 30bto facilitate preferential bending at the location of the notches. In another embodiment, the mandrels are a shape memory alloy such as nitinol having a preferential bend formed therein. In lieu of placing mandrels 30a,30bwithin lumens 22a,22b,stiffening mandrels 30a,30bcan be affixed to the exterior of tubes 27a, 27bas shown in FIG. 3B.

[0037] The mandrels are typically 0.003″ to 008″ wide. If the mandrels are not within lumens 22aand 22bthose lumens are typically 0.006″ to 0.016″ wide (i.e. an inner diameter of 0.006″ to 0.016″). If the mandrels are within lumens 22aand 22b,lumens 22aand 22bare typically 0.009″ to 0.020″ wide.

[0038] Guide wire lumen 12 is typically about 0.010″ to 0.040″ wide depending upon where the catheter is to be used. For coronary artery applications, lumen 12 is about 0.012″ to 0.018″ wide. For peripheral arteries, lumen 12 can be as wide as 0.040″.

[0039] FIG. 4 illustrates an alternative embodiment of the invention in which a catheter 10′ includes a balloon 32 coupled to a balloon inflation lumen 34. Balloon 32 can be constructed in the same manner as a PTCA (percutaneous transluminal coronary angioplasty) balloon. Alternatively, balloon 32 can be doughnut shaped.

[0040] Operation of catheter 10′ is similar to that of catheter 10 shown in FIGS. 2 and 3. A physician first inserts guide wire 14 into the patient, and then advances catheter 10′ over guide wire 14 until hollow needles 26a, 26bare at an appropriate location. When it is desired to insert needles 26a, 26binto the patient's artery wall, a physician injects inflation fluid through a balloon inflation port 35 at the proximal end 10p′ of catheter 10′ through balloon inflation lumen 34 into balloon 32. Balloon 32 then expands and pushes needles 26a, 26boutwardly into the artery wall. In other words, needles 26a, 26bare rotated outwardly away from the longitudinal axis of catheter 10′ (Arrow AC in FIG. 4 is parallel to the longitudinal catheter axis. Arrow AN is the longitudinal needle axis.) During this process, the points adjacent where tube 27a, 27bcontact shrink tube 24 act as a hinge. Drugs can then be injected through drug delivery port 18, single drug delivery lumen 20, lumens 22a,22band needles 26a, 26b.Thereafter, needles 26a, 26bare retracted by deflating balloon 32 (i.e., by withdrawing inflation fluid from balloon 32 via balloon inflation lumen 34 and balloon inflation port 35). Catheter 10′ is then withdrawn from the patient. Balloon 32 is typically affixed to tubes 27a, 27bat points 32a,32bwith an adhesive such as epoxy. (Alternatively, balloon 32 can be affixed to tubes 27a, 27bby other methods, such as welding.) Thus, when balloon 32 is deflated and contracts, it rotationally pulls needles 26 inwardly and substantially parallel to the longitudinal catheter axis AC so that needles 26 will not drag along the artery wall when the catheter 10′ is retracted. (In other words, the longitudinal needle axes AN are rotated to be substantially parallel to the longitudinal catheter axis AC.) Although not shown in FIG. 4, tubes 27a, 27bcan include mandrels 30a,30bto enhance their stiffness, as described above with respect to FIGS. 2, 3, 3A, and 3B.

[0041] Balloon 32 can be shaped like a conventional dilatation catheter balloon (e.g. the same length and profile). Alternatively, balloon 32 may be shorter than a conventional dilatation catheter. In one embodiment, balloon 32 has a length L3 between 3 and 10 mm.

[0042] As can be seen, in the embodiment of FIG. 4, the proximal portion 10p′ of catheter 10′ includes a single drug delivery lumen 20 which divides into two (or more) lumens 22a,22b.In the embodiment shown in FIG. 4E, the distal end 10d′ of catheter 10′ which includes shrink tube 28 (as shown in FIG. 4), is not included.

[0043] FIGS. 4A, 4B, and 4C illustrate in cross section portions of catheter 10′ along lines A—A, B—B, and C—C, respectively. FIG. 4A shows single drug delivery lumen 20, balloon inflation lumen 34, guide wire lumen 12, and guide wire 14. FIG. 4B shows a cross sectional portion of catheter 10′ after single drug delivery lumen 20 has divided into two drug delivery lumens 22a,22bsurrounded by tubes 27a, 27b. Finally, FIG. 4C illustrates a cross-sectional view of catheter 10′ along line C—C, with inflated balloon 32 pushing tubes 27a, 27bin an angle away from the longitudinal axis of catheter 10′. While FIGS. 4, 4A, 4B, and 4C illustrate a single drug delivery lumens 20, in other embodiments a single drug delivery lumens 20 is not used, and lumens 22a,22bextend to drug delivery port 18.

[0044] As with the embodiment of FIG. 3, the length of the portion of tubes 27a, 27bdistal to shrink tube 24 can vary. In one embodiment, when needles 26a, 26bare in their extended position, they only extend a short distance past the top of balloon 32. In other embodiments, needles 26a, 26bcan extend a longer distance past the top of balloon 32.

[0045] FIG. 5 illustrates a catheter similar to that of FIG. 4 except that a balloon 32 has a short length. When balloon 32 is inflated, proximal end 32′ of balloon 32 forms a steep step. Needles 26a, 26bextend only a very short distance beyond surface 32″ of balloon 32, and are deployed at a near-perpendicular angle with respect to the longitudinal catheter axis in FIG. 5. However, when balloon 32 is deflated, needles 26a, 26bare brought to an angle parallel or substantially parallel to the longitudinal catheter axis.

[0046] In FIGS. 4, 4E, and 5, balloon 32 is substantially cylindrical. However, FIG. 4D illustrates in cross section along lines C—C an embodiment of a catheter comprising a balloon 33 which, when inflated, has a clover-like cross section including large wide sections 33aand narrow sections 33b.Narrow sections 33badvantageously permit blood to perfuse past balloon 33 when the catheter is being used and balloon 33 is inflated.

[0047] FIG. 4D shows four tubes 27 instead of two tubes 27a, 27b. However, as mentioned above, different numbers of tubes 27 can be used.

[0048] In lieu of the balloon shapes shown in FIGS. 4, 5, and 4D, a helical balloon 35 as shown in FIG. 6 can be employed. The helical shape of balloon 35 facilitates blood perfusion past balloon 35 during use.

[0049] In the above embodiments, the catheter in accordance with the present invention may be used in conjunction with a thin cylindrical sheath 40. FIG. 7 shows catheter 10 of FIG. 2 used in conjunction with a sheath 40 that may be used to surround a portion of catheter 10 to cover needles 26a, 26b(and balloon 32, 33, or 36, in the case of an embodiment including a balloon 32, 33, or 36). Sheath 40 keeps needles 26a, 26bclose to the catheter body, thereby ensuring a low profile, and ensuring that needles 26a, 26bstay aligned with the longitudinal axis of catheter 10. When catheter 10 is inserted into the patient's blood vessel at the desired position, sheath 40 extends proximally out of the patient's blood vessel so that the physician can manipulate the sheath 40. A sheath removal handle 42 is affixed to the proximal end of sheath 40. Sheath 40 may be pulled back once the catheter 10 is at a desired position before extending needles 26a, 26band delivering the drug or medication. After use, sheath 40 can be advanced in the distal direction to again cover needles 26a, 26bprior to retracting the catheter 10.

[0050] In the above-described embodiments, various structures in the catheter 10 can be formed from radiopaque materials so that the position of catheter 10 may be easily observed during use. For example, the needles 26a, 26bmay be radiopaque. This can be accomplished, e.g., by plating needles 26a, 26bwith or constructing needles 26a, 26bfrom a radiopaque material such as titanium or tungsten. Alternatively, radiopaque materials may be placed on the catheter near needles 26a, 26bor preferential bending points P1 to P6. Alternatively, radiopaque materials may be placed on the balloon 32, 33, 36.

[0051] The above-described embodiment incorporates shrink tubing, e.g., shrink tubes 24 and 28, to hold various tubes of the catheter 10 together. In lieu of, or in addition to such shrink tubing, the various catheter tubes can be held together by other means, e.g., adhesive heat fusing. Alternatively, the tubes can be coextruded together and then separated by cutting at those locations where the tubes must be permitted to slide relative to one another.

[0052] A catheter 10 in accordance with the invention has numerous advantages:

[0053] 1) The catheter 10 permits blood perfusion (i.e. blood flow around the catheter 10), enabling the catheter 10 to remain within the blood vessel for as long as deemed necessary by the attending physician. This is because the catheter 10 does not block the entire artery lumen even when needles 26a, 26bare extended outwardly.

[0054] 2) The catheter 10 is typically very flexible, permitting access to distal, tortuous arteries. The reason for this is that the stiff portion of the catheter 10 (the portion of the length along which needles 26a, 26bextend) is very small.

[0055] 3) While the catheter is being positioned, needles 26a, 26blie in the axial direction of catheter 10 substantially parallel to the longitudinal axis AC of catheter 10, thereby minimizing the profile of the catheter 10 and minimizing the chance of injury to the artery.

[0056] While the invention has been described with regard to specific embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. For example, the material from which the catheter is made can be any extruded polymer or metal, including shape memory metals or a combination thereof. Also, although the embodiments of FIGS. 2 to 7 contain a guide wire lumen 12, and are used in conjunction with a guide wire 14, other embodiments are not used in conjunction with a guide wire 14. In alternative embodiments, a guide wire 14 is not used, and the space which would otherwise be occupied by guide wire lumen 12 is sealed.

[0057] In yet another embodiment, guide wire lumen 12 does not extend the entire length of catheter 10. Instead, guide wire lumen 12 terminates between 1 and 35 cm from distal end 10dof catheter 10, and guide wire 14 extends through only the distal 1 to 35 cm of catheter 10. This facilitates rapid exchange of catheter 10 over guide wire 14.

[0058] In yet another embodiment, the catheter can contain other lumens for performing other functions. For example, one can place balloons proximal to shrink tube 24 and distal to shrink tube 28 to prevent medication from diffusing away from the injection site.

[0059] Needles 26a, 26bcan extend greater or lesser distances D2 past tubes 27a, 27b. Also, in some embodiments, tubes 27a, 27band needles 26a, 26bcan be extended at angles closer to or further from right angles than illustrated in FIGS. 3 to 6. The angle at which tubes 27a, 27band needles 26a, 26bare extended is typically between 45 and 100°.

[0060] In some embodiments, the catheter is used in vessels other than arteries. Accordingly, all such changes come within the invention.